Sample records for gadolinium gallium garnet

  1. LASERS: Efficient neodymium-doped gadolinium gallium garnet crystal laser

    NASA Astrophysics Data System (ADS)

    Doroshenko, Maxim E.; Osiko, Vyacheslav V.; Sigachev, V. B.; Timoshechkin, M. I.

    1991-07-01

    An investigation was made of the stimulated emission parameters of a laser utilizing a gadolinium gallium garnet crystal doped with neodymium ions (YAG:Nd) at the 1.062 ?m wavelength. The free-running efficiency was the highest so far achieved for flashlamp-pumped lasers utilizing unsensitized garnets. For an active element 8 mm in diameter and 120 mm long the absolute efficiency was 5.4% and the differential efficiency was 5.9%. The average free-running power was 170 W. A comparison was made of the optical powers of thermal lenses in cylindrical GGG:Nd and YAG:Nd active elements and this was found to be 2.4 times higher for a GGG:Nd crystal at the same pump powers. It was shown that by using traditional methods of compensating for the thermal lens in cylindrical active elements, it is possible to develop pulsed GGG:Nd crystal lasers having an average output power higher than 100 W, an efficiency of ~ 4%, and an angular divergence of less than 10 mrad.

  2. Thermodynamic property evaluation and magnetic refrigeration cycle analysis for gadolinium gallium garnet

    SciTech Connect

    Murphy, R.W.

    1994-12-01

    Based on relevant material property data and previous model formulations, a magnetothermodynamic property map for gadolinium gallium garnet (Gd{sub 3}Ga{sub 5}O{sub 12}) was adapted for refrigeration cycle analysis in the temperature range 4-40 K and the magnetic field range 0-6 T. Employing methods similar to those previously developed for other materials and temperature ranges, assessments of limitations and relative performance were made for Carnot, ideal regenerative, and pseudo-constant field regenerative cycles. It was found that although Carnot cycle limitations on available temperature lift for gadolinium gallium garnet are not as severe as the limitations for materials previously examined, considerable improvement in cooling capacity and temperature lift combinations can be achieved by using regenerative cycles if serious loss mechanisms are avoided.

  3. Epitaxial Growth of Atomically Flat Yttrium Iron Garnet Thin Films on Gadolinium Gallium Garnet by Pulse Laser Deposition

    NASA Astrophysics Data System (ADS)

    Lin, Tao; Tang, Chi; Shi, Jing

    2013-03-01

    Yttrium iron garnet (YIG) is a ferrimagnetic insulator which is useful for magneto-optical, microwave, and more recently spintronic devices. Pulsed laser deposition (PLD) has emerged as a preferred technique to deposit complex oxide thin films, heterostructures, and superlattices with high quality. Deposition of YIG films using PLD has been reported by several groups. The layer-by-layer growth mode has been achieved with a high laser repetition rate. No details about surface morphology were discussed. Here we report our approach to grow YIG films with thickness ranging from 10 to 100 nm on (110)- and (111)-oriented gadolinium gallium garnet (GGG) substrates. In both orientations, we have successfully grown epitaxial YIG thin films confirmed by the patterns of the reflection high-energy electron diffraction. The magnetic properties are measured by a vibrating sample magnetometer. The in-plane easy-axis coercivity is less than 1 Oe, while the perpendicular saturation field is ~ 2000 Oe. For both orientations, the atomic force microscopy images show that the YIG surface is extremely flat with roughness ~ 0.6Å. Flat terraces are found with the atomic step height in films with both orientations. This work paves the way to engineering anisotropy of the thin films for YIG-based magnetic devices. Yttrium iron garnet (YIG) is a ferrimagnetic insulator which is useful for magneto-optical, microwave, and more recently spintronic devices. Pulsed laser deposition (PLD) has emerged as a preferred technique to deposit complex oxide thin films, heterostructures, and superlattices with high quality. Deposition of YIG films using PLD has been reported by several groups. The layer-by-layer growth mode has been achieved with a high laser repetition rate. No details about surface morphology were discussed. Here we report our approach to grow YIG films with thickness ranging from 10 to 100 nm on (110)- and (111)-oriented gadolinium gallium garnet (GGG) substrates. In both orientations, we have successfully grown epitaxial YIG thin films confirmed by the patterns of the reflection high-energy electron diffraction. The magnetic properties are measured by a vibrating sample magnetometer. The in-plane easy-axis coercivity is less than 1 Oe, while the perpendicular saturation field is ~ 2000 Oe. For both orientations, the atomic force microscopy images show that the YIG surface is extremely flat with roughness ~ 0.6Å. Flat terraces are found with the atomic step height in films with both orientations. This work paves the way to engineering anisotropy of the thin films for YIG-based magnetic devices. This work was supported in part by DMEA and DOE.

  4. Optical properties of bismuth and gallium substituted thulium iron garnet films

    Microsoft Academic Search

    R. Gerhardt; S. Sure; H. Dötsch; T. Linkewitz; W. Tolksdorf

    1993-01-01

    Bismuth and gallium substituted films of thulium iron garnet, grown by liquid phase epitaxy on [111] oriented substrates of gadolinium gallium garnet, are investigated for optical isolator applications. At a wavelength of lambda = 1.3 mum the optical damping, the refractive index, the optical anisotropy, and the Faraday rotation are measured as function of the substitution level. It turns out

  5. Terbium gallium garnet Verdet constant measurements with pulsed magnetic field

    Microsoft Academic Search

    A. B. Villaverde; D. A. Donatti; D. G. Bozinis

    1978-01-01

    The dispersion of the Verdet constant of a single-crystal terbium gallium garnet (TGG) was measured using a pulsed magnetic field up to 70 KG. The data show a large Verdet constant for TGG throughout the visible region. The observed hysteresis effect is briefly discussed.

  6. Terahertz Cherenkov radiation from ultrafast magnetization in terbium gallium garnet

    NASA Astrophysics Data System (ADS)

    Gorelov, S. D.; Mashkovich, E. A.; Tsarev, M. V.; Bakunov, M. I.

    2013-12-01

    We report an experimental observation of terahertz Cherenkov radiation from a moving magnetic moment produced in terbium gallium garnet by a circularly polarized femtosecond laser pulse via the inverse Faraday effect. Contrary to some existing theoretical predictions, the polarity of the observed radiation unambiguously demonstrates the paramagnetic, rather than diamagnetic, nature of the ultrafast inverse Faraday effect. From measurements of the radiation field, the Verdet constant in the subpicosecond regime is ˜3-10 times smaller than its table quasistatic value.

  7. The magnetostriction of rare-earth garnets containing gallium and europium: Old theory for new problems

    Microsoft Academic Search

    R. White

    1973-01-01

    A calculation is made of the effect of gallium substitution upon the magnetostriction of rare-earth garnets, a problem of some interest because of the use of gallium substituted garnets as bubble-domain materials. The gallium alters the contribution to magnetostriction of the iron lattices by simple dilution and of the rare-earth lattice by reducing the exchange field acting upon the rare-earth

  8. Plasmon resonance enhancement of Faraday rotation in thin garnet films

    NASA Astrophysics Data System (ADS)

    Tkachuk, S.; Lang, G.; Krafft, C.; Rabin, O.; Mayergoyz, I.

    2011-04-01

    Garnet films have been grown over (100)-oriented substituted gadolinium gallium garnet substrates partially populated with gold nanoparticles in order to study plasmon resonance enhancement of magneto-optic effects. The results of measurements of light transmission through these films as well as Faraday rotation are reported.

  9. Defects in laser crystals of rare-earth aluminum and gallium garnets

    SciTech Connect

    Vorob`ev, Yu.P.; Goncharov, O.Yu. [Physicotechnical Institute, Izhevsk (Russian Federation)

    1994-12-01

    Using thermodynamic and crystallochemical analysis of garnets R{sub 3}Ga{sub 5}O{sub 12}(R=Sm - Lu, Y) and R{sub 3}Al{sub 5}O{sub 12} (R = Gd - Lu, Y) and their solid solutions, we characterized point defects present in their structure and, for the first time, estimated their contents. We showed that the garnets under consideration contain cationic defects and oxygen vacancies: (1) In aluminum garnets R{sub 3}Al{sub 5}O{sub 12}, improper-valence ions form at octahedral sites. (2) In gallium garnets R{sub 3}Ga{sub 5}O{sub 12} and Ga-containing solid solutions, there are Ga vacancies at octahedral sites. (3) In Dy{sub 3}(Ga{sub c}Al{sub 1-c}){sub 5}O{sub 12} solid solutions, in addition to the above-mentioned defects typical of gallium garnets, antistructural, substitutional defects (Ga{sup 3+}{sub IV}) are present. The Ga{sup 3+}ions occupy preferentially octahedra; that is, they exhibit a higher affinity for octahedral coordination than Alk{sup 3+} ions, in agreement with Goldschmidt`s crystallochemical approach. The refined solid-solution ranges for R{sub 3}Ga{sub c}Al{sub 1-c}{sub 5}O{sub 12}(R=Nd,Sm,Eu,Gd) are 0.75 {le}c{le} 1 for Nd, 0.5 {le}c{le} 1 for Sm, 0.4 {le}c{le} 1 for Eu, and 0.25 {le}c{le} 1 for Gd.

  10. Fabrication and characterization of cerium-doped terbium gallium garnet with high magneto-optical properties.

    PubMed

    Chen, Zhe; Hang, Yin; Yang, Lei; Wang, Jun; Wang, Xiangyong; Hong, Jiaqi; Zhang, Peixiong; Shi, Chunjun; Wang, Yaqi

    2015-03-01

    High optical quality (Tb((1-x))Ce(x))?Ga?O?? (TCGG) single crystal has been grown by the Czochralski method. The optical and magneto-optical properties of the TCGG are analyzed in detail and the Verdet constant (V) of TCGG is compared with that of undoped terbium gallium garnet (TGG) crystal. TCGG presents a very high transmittance, particularly in the visible-near infrared (VIS-NIR) region, and its V is obviously larger than that of TGG in the VIS-NIR region. The figure of merit and optical features point out the superior characteristics of TCGG with respect to TGG. PMID:25723441

  11. Optical properties and Faraday effect of ceramic terbium gallium garnet for a room temperature Faraday rotator.

    PubMed

    Yoshida, Hidetsugu; Tsubakimoto, Koji; Fujimoto, Yasushi; Mikami, Katsuhiro; Fujita, Hisanori; Miyanaga, Noriaki; Nozawa, Hoshiteru; Yagi, Hideki; Yanagitani, Takagimi; Nagata, Yutaka; Kinoshita, Hiroo

    2011-08-01

    The optical properties, Faraday effect and Verdet constant of ceramic terbium gallium garnet (TGG) have been measured at 1064 nm, and were found to be similar to those of single crystal TGG at room temperature. Observed optical characteristics, laser induced bulk-damage threshold and optical scattering properties of ceramic TGG were compared with those of single crystal TGG. Ceramic TGG is a promising Faraday material for high-average-power YAG lasers, Yb fiber lasers and high-peak power glass lasers for inertial fusion energy drivers. PMID:21934880

  12. Optical properties and Faraday effect of ceramic terbium gallium garnet for a room temperature Faraday rotator

    NASA Astrophysics Data System (ADS)

    Yoshida, Hidetsugu; Tsubakimoto, Koji; Fujimoto, Yasushi; Mikami, Katsuhiro; Fujita, Hisanori; Miyanaga, Noriaki; Nozawa, Hoshiteru; Yagi, Hideki; Yanagitani, Takagimi; Nagata, Yutaka; Kinoshita, Hiroo

    2011-08-01

    The optical properties, Faraday effect and Verdet constant of ceramic terbium gallium garnet (TGG) have been measured at 1064 nm, and were found to be similar to those of single crystal TGG at room temperature. Observed optical characteristics, laser induced bulk-damage threshold and optical scattering properties of ceramic TGG were compared with those of single crystal TGG. Ceramic TGG is a promising Faraday material for high-average-power YAG lasers, Yb fiber lasers and high-peak power glass lasers for inertial fusion energy drivers.

  13. Ultrafast inverse Faraday effect in a paramagnetic terbium gallium garnet crystal

    NASA Astrophysics Data System (ADS)

    Mikhaylovskiy, R. V.; Hendry, E.; Kruglyak, V. V.

    2012-09-01

    Conventional wisdom dictates that magneto-optical and optomagnetic phenomena are reciprocal and of equal strength. We test this assumption in a pump-probe experimental study of the ultrafast inverse Faraday effect in a terbium gallium garnet crystal. The thorough quantitative analysis of the observed polarization response unambiguously demonstrates a remarkable discrepancy of several orders of magnitude between the strengths of the direct and the inverse effects. This finding further questions the validity of standard magnetic models relying on the use of the static Verdet constant on subpicosecond time scales.

  14. Nonlinear field dependence of the Faraday effect in neodymium gallium garnet under high magnetic field

    NASA Astrophysics Data System (ADS)

    Gu, Ming; Wang, Wei; Liu, Gongqiang

    2008-01-01

    In this paper, we present a theoretical investigation on the Faraday effect in paramagnetic neodymium gallium garnet (Nd 3Ga 5O 12) by taking account of the SO and CF interactions, the superexchange interaction and the external magnetic field. It is demonstrated that under high magnetic field, the Faraday rotation ( ?) is strongly nonlinear with the external magnetic field ( He) while the coefficients of Hei deeply dependent on the frequency of the incident light and temperature, and the Verdet constant V( ?/ He) is also a function of He. Furthermore, theoretical calculations show that the reciprocity of the Faraday effect cannot be neglected under high magnetic field. The theoretical results are in good agreement with the experimental data.

  15. Stabilization of cubic lithium-stuffed garnets of the type “Li7La3Zr2O12” by addition of gallium

    NASA Astrophysics Data System (ADS)

    El Shinawi, Hany; Janek, Jürgen

    2013-03-01

    Cubic lithium-stuffed garnets of the type Li7La3Zr2O12 have been successfully stabilized by incorporation of gallium. The materials have been prepared by a sol-gel procedure with final calcination at 1085 °C for 6 h. Under the applied synthesis conditions, 0.3 mole of gallium ions (per mole of Li7La3Zr2O12) were sufficient to fully stabilize the cubic garnet-type phase. Increasing the fraction of gallium led to significant improvement of sinterability and lithium ion conductivity. Excess gallium ions, in the form of LiGaO2, act as a sintering aid and reside exclusively at the grain boundaries. The gallium-modified garnets showed conductivities up to 5.4 × 10-4 S cm-1 at 20 °C, and activation energies in the range 0.32-0.37 eV.

  16. Low-temperature synthesis and characterization of yttrium–gallium garnet Y 3Ga 5O 12 (YGG)

    Microsoft Academic Search

    Sanjay Mathur; Hao Shen; Asta Leleckaite; Aldona Beganskiene; Aivaras. Kareiva

    2005-01-01

    To obtain yttrium–gallium garnet (Y3Ga5O12, YGG) a simple “chimie douce” method has been developed. This sol–gel method yielded excellent starting gel precursor for the fabrication of YGG phase, which could be used as host material for optical applications. The pattern of X-ray diffraction analysis of the ceramic sample sintered for 10h at 1000°C showed the formation of monophasic Y3Ga5O12 phase.

  17. Enhanced microwave ferromagnetic resonance absorption and bandwidth using a microstrip meander line with step-impedance low-pass filter in a yttrium iron garnet-gallium arsenide layer structure

    NASA Astrophysics Data System (ADS)

    Qiu, Gang; Tsai, Chen S.; Kobayashi, Masatoshi M.; Wang, Bert S. T.

    2008-04-01

    Simulations of the step-impedance low-pass filter (LPF) in gallium arsenide (GaAs) substrate show that, in contrast to a 50? microstrip, the magnetic fields of the propagating microwaves are heavily concentrated in its inductive elements. The concentrated local magnetic fields facilitate enhanced coupling into an yttrium iron garnet/gadolinium gallium garnet layer over the GaAs substrate and, thus, significantly increase the microwave power absorptions at the ferromagnetic resonance (FMR) frequencies. The large tunable range of FMR frequency and the corresponding S21 and S11 parameters measured have verified the simulation results. Simultaneous enhancement of FMR absorption level and widening of absorption bandwidth has been accomplished in a band-stop filter that utilizes a microstrip meander line with four identical step-impedance LPFs, each of 5.70mm long, inserted in a nonuniform bias magnetic field. A tunable FMR absorption frequency range of 5-21GHz, an absorption level of -35.5dB, and a corresponding 3dB absorption bandwidth as large as 1.70GHz, centered at 20.3GHz, have been demonstrated.

  18. Dispersionless Spin Waves and Underlying Field-Induced Magnetic Order in Gadolinium Gallium Garnet

    NASA Astrophysics Data System (ADS)

    d'Ambrumenil, N.; Petrenko, O. A.; Mutka, H.; Deen, P. P.

    2015-06-01

    We report the results of neutron diffraction and inelastic neutron scattering on a powder sample of Gd3Ga5O12 at high magnetic fields. Analysis of the diffraction data shows that in high fields (B ?1.8 T ) the spins are not fully aligned, but are canted slightly as a result of the dipolar interaction. The magnetic phase for fields ?1.8 T is characterized by antiferromagnetic peaks at (210) and an incommensurate wave vector. The dominant contribution to inelastic scattering at large momentum transfers is from a band of almost dispersionless excitations. We show that these correspond to the spin waves localized on ten site rings, expected on the basis of nearest neighbor exchange interaction, and that the spectrum at high fields B ?1.8 T is well described by a spin wave theory.

  19. Complete Stokes polarimetry of magneto-optical Faraday effect in a terbium gallium garnet crystal at cryogenic temperatures.

    PubMed

    Majeed, Hassaan; Shaheen, Amrozia; Anwar, Muhammad Sabieh

    2013-10-21

    We report the complete determination of the polarization changes caused in linearly polarized incident light due to propagation in a magneto-optically active terbium gallium garnet (TGG) single crystal, at temperatures ranging from 6.3 to 300 K. A 28-fold increase in the Verdet constant of the TGG crystal is seen as its temperature decreases to 6.3 K. In contrast with polarimetry of light emerging from a Faraday material at room temperature, polarimetry at cryogenic temperatures cannot be carried out using the conventional fixed polarizer-analyzer technique because the assumption that ellipticity is negligible becomes increasingly invalid as temperature is lowered. It is shown that complete determination of light polarization in such a case requires the determination of its Stokes parameters, otherwise inaccurate measurements will result with negative implications for practical devices. PMID:24150356

  20. Growth of terbium gallium garnet (TGG) magneto-optic crystals by edge-defined film-fed growth method

    NASA Astrophysics Data System (ADS)

    Zhuang, Naifeng; Song, Caigen; Guo, Liwei; Wang, Rongfeng; Hu, Xiaolin; Zhao, Bin; Lin, Shukun; Chen, Jianzhong

    2013-10-01

    Although terbium gallium garnet (TGG) single crystals suitable for practical applications have been grown by the Czochralski technique due to its congruent melting nature, the interface shape readily deteriorates to spiral growth when grown with a flat interface or facet formation when grown with a convex interface. The Edge-defined Film-fed Growth (EFG) method was used to grow TGG crystals for the first time. The influence of the raw material sintering temperature, growth atmosphere, growth rate and other growth conditions on the crystal quality were investigated. The Verdet constant of as-grown crystal was measured as 39 rad/T.m at 1064 nm by the extinction method, which was close to the literature value. The source of color centers in the crystals is also discussed.

  1. Low-temperature high-pressure spectroscopy of lanthanum lutetium gallium garnet crystals doped with Cr3+ and Nd3+

    NASA Astrophysics Data System (ADS)

    Kami?ska, A.; Kaczor, P.; Durygin, A.; Suchocki, A.; Grinberg, M.

    2002-03-01

    Low-temperature luminescence measurements under high pressures in diamond-anvil cell of nonstoichiometric lanthanum lutetium gallium garnet (LLGG) doped with Cr3+ ions and nonintentionally with Nd3+ ions are reported. Three nonequivalent Cr3+ centers were found in the crystal using this technique. The results also reveal information about the electronic structure of different Cr3+ centers in those crystals. Cr3+ ions in a LLGG crystal experience a very low crystal field strength. The energy differences between the 4T2 and 2E levels are negative, and equal to about -1100 cm-1 for two of those centers and about -1500 cm-1 for the third one. The spectral results were corroborated by a theoretical analysis of the luminescence decay times as a function of pressure, which allowed one to establish the exact values of the crystal-field parameter Dq at ambient pressure for those centers. The crystal exhibits a large inhomogeneous broadening of the R lines, associated with nonstoichiometry. In addition to the Cr3+ luminescence also luminescence of Nd3+ ions was detected in the LLGG crystals. One of the Nd3+ luminescence lines, associated with the 4F3/2-->4I9/2 transition, is strongly dependent on pressure, with a pressure coefficient equal to 0.96+/-0.02 cm-1/kbar, which makes this system interesting as a pressure gauge in the infrared region.

  2. Gallium

    SciTech Connect

    NONE

    1996-01-01

    Discovered in 1875 through a study of its spectral properties, gallium was the first element to be uncovered following the publication of Mendeleev`s Periodic Table. French chemist, P.E. Lecoq de Boisbaudran, named his element discovery in honor of his native country; gallium is derived from the Latin word for France-{open_quotes}Gallia.{close_quotes}. This paper describes the properties, sources, and market for gallium.

  3. Optical study of magnetostriction in (Bi, Ga)-substituted garnet thin films

    NASA Astrophysics Data System (ADS)

    Nistor, I.; Mayergoyz, I. D.; Rojas, R.; Krafft, C.

    2005-10-01

    The magnetostriction of magnetically diluted (Lu3-xBixFe5-yGayO12) (BiLuIG) thin films grown by epitaxial deposition on (111)-oriented gallium gadolinium garnet substrates was optically studied using the technique based on the bending of samples by an external applied pressure. The real-time optical observations of stripe magnetic domains and their evolution under external applied magnetic fields and applied stresses are reported. The observed changes in the magnetic domain structure are used to infer the magnetostriction coefficient ?111 of garnet films.

  4. Improved laser efficiency by direct diode laser pumping of the radiation-resistant Nd:gadolinium–scandium–gallium garnet

    NASA Astrophysics Data System (ADS)

    Lupei, V.; Pavel, N.; Lupei, A.

    2014-04-01

    Spectroscopic investigation of the radiation-resistant Nd:GSGG crystals and ceramics reported in this paper evidences that the absorption line at 883 nm corresponding to the unusual situation of quasi-degenerate absorption transitions 4I9/2(2) ?4F3/2(1) and 4I9/2(3) ?4F3/2(2) can be used for efficient direct diode laser pumping of this material, with stable absorption over an extended temperature range. It is inferred that the reduction of the quantum defect at this wavelength of pump compared to the traditional 807 nm pumping could improve the laser parameters and reduce drastically the heat generation, leading to a considerable extension of the power scalability. This possibility is demonstrated for the first time in the case of the 1061 nm laser emission in a continuous-wave and in the repetitive active acousto-optic and passive Q-switched laser emission. In all regimes this manifests in the reduction of the laser threshold, increase of slope efficiency and extension of the average power range. Additionally, in the active Q-switching this enables increased pulse energy and reduced pulse duration. The direct pumping could revitalize the utilization of Nd:GSGG for construction of lasers with storage of population inversion or working in an ionizing radiation environment.

  5. Crystal Field in Dysprosium Garnets

    Microsoft Academic Search

    P. Grünberg; S. Hüfner; E. Orlich; J. Schmitt

    1969-01-01

    The crystal-field splittings of the 6H and 6F multiplets of Dy3+ in yttrium gallium garnet and yttrium aluminum garnet have been determined from absorption and emission spectra. In addition, the g factors of some crystal-field levels have been determined from Zeeman-effect measurements. All these experimental data are used to derive a set of crystal-field parameters for the two garnet systems.

  6. The effect of an erbium, chromium: yttrium-scandium-gallium-garnet laser on the microleakage and bond strength of silorane and micro-hybrid composite restorations

    PubMed Central

    Korkmaz, Fatih Mehmet; Baygin, Ozgul; Tuzuner, Tamer; Bagis, Bora; Arslan, Ipek

    2013-01-01

    Objective: The aim of this in vitro study was to compare the microleakage and bond strength of Class V silorane-based and universal micro-hybrid composite restorations prepared either with diamond bur or with an erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr:YSGG) laser. Materials and Methods: A total of 160 molar teeth were used for microleakage assessment and shear bond strength (SBS) test. The specimens were prepared using either diamond bur or 3 W-, 4 W- and 5 W-20 Hz Er, Cr:YSGG laser irradiation. All specimens were subjected to thermocycling (500 times at 5 ± 2°C to 55 ± 2°C, dwell time 15 s and transfer time 10 s). Microleakage was assessed using a 0.5% basic-fuchsin solution. The bond strengths were determined using a microtensile tester at a crosshead speed of 0.5 mm/min. The Kruskal Wallis test was used for the analysis of microleakage and a one-way analysis of variance test was used to analyze the SBS (P < 0.05). Results: No statistically significant differences were found (P > 0.05) between Er, Cr:YSGG laser and bur preparation methods regarding microleakage and bond strength values. Conclusion: Irradiation with Er, Cr:YSGG laser was confirmed to be as effective as conventional methods for preparing cavities before adhesive restorations. PMID:24966726

  7. Effects of root planing procedures with hand instrument or erbium, chromium:yttrium-scandium-gallium-garnet laser irradiation on the root surfaces: a comparative scanning electron microscopy study.

    PubMed

    Hakki, Sema S; Berk, Gizem; Dundar, Niyazi; Saglam, Mehmet; Berk, Nukhet

    2010-05-01

    The purpose of this study was to investigate the efficiency of hand instrumentation and laser irradiation on calculus removal from the root surfaces, in vitro. Thirty-two human teeth, extracted for periodontal reasons, were used in this study. Root surfaces of single-rooted teeth were treated by different methods including (1) conventional hand instruments; (2) hand instruments and tetracycline-hydrochloride (Tet-HCl); (3) erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser irradiation, setting I (short pulse); (4) Er,Cr:YSGG laser irradiation, setting II (long pulse). Three premolar teeth, extracted for orthodontic reasons, served as control. The morphology of the root surfaces was evaluated by light and scanning electron microscopy. Energy dispersive X-ray (EDX) analysis was performed to compare the mineral content of root surfaces treated with hand instrumentation and lasing procedures. The results of this study demonstrated that all treatments were efficient in calculus removal from the root surfaces. Thermal changes, including melting and carbonization, were not observed in either lasing procedure. The surface was rougher in the laser groups than in the groups treated with hand instruments. Moreover, roughness was greater in the long-pulse laser setting than in the short-pulse setting. While increased calcium (Ca) and decreased phosphate (P) (weight concentration percent) were observed in all treatments when compared with the control, laser procedures resulted in a more similar mineral content than in the groups treated with hand instruments. Based on these findings, laser procedures, when used in appropriate settings, are capable of performing scaling and root planing in the treatment of periodontitis. It may be concluded that short pulse laser may be more suitable for the micro-morphology of the root surface. However, additional in vitro and clinical studies are necessary to clarify the success of laser in periodontal therapy. PMID:19219484

  8. The effect of erbium, chromium:yttrium-scandium-gallium-garnet laser etching on marginal integrity of a resin-based fissure sealant in primary teeth.

    PubMed

    Sungurtekin, Elif; Ozta?, Nurhan

    2010-11-01

    The aim of this in vitro study was to evaluate the effect of erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser pretreatment alone, or associated with acid etching, on the quality of marginal integrity (microleakage and marginal gap) of a resin-based fissure sealant in primary teeth. Fifty sound primary molar teeth were randomly assigned to one of five study groups, pretreated as follows: (1) 35% orthophosphoric acid etching; (2) 2.5 W laser etching; (3) 3.5 W laser etching; (4) 2.5 W laser + 35% orthophosphoric acid etching; (5) 3.5 W laser + 35% orthophosphoric acid etching. After surface pretreatment, a resin-based sealant (ClinPro) was applied to the fissures. Sample teeth were then subjected to thermocycling and stored thereafter in distilled water at 37 degrees C for 1 month. Following immersion in 0.5% basic fuchsin solution for 24 h, three bucco-lingual slices of each sample tooth were scored under a stereo-microscope. Statistical analysis was performed with Kruskal-Wallis one-way analysis of variance (ANOVA) and Pearson chi-square tests. The level of significance was set at P < 0.05. Microleakage scores of group 1 were significantly less than those of groups 2 and 3 (P < 0.05), whereas no statistically significant difference was observed between groups 1, 4 and 5 (P > 0.05). In terms of marginal gap formation, no significant difference was observed between groups (P > 0.05). It was concluded that Er,Cr:YSGG laser etching did not eliminate the need for acid etching. When combined with acid etching, Er,Cr:YSGG laser seems to be as effective as conventional acid etching. PMID:19653059

  9. Effects of root planing procedures with hand instrument or erbium, chromium:yttrium–scandium–gallium–garnet laser irradiation on the root surfaces: a comparative scanning electron microscopy study

    Microsoft Academic Search

    Sema S. Hakki; Gizem Berk; Niyazi Dundar; Mehmet Saglam; Nukhet Berk

    2010-01-01

    The purpose of this study was to investigate the efficiency of hand instrumentation and laser irradiation on calculus removal\\u000a from the root surfaces, in vitro. Thirty-two human teeth, extracted for periodontal reasons, were used in this study. Root\\u000a surfaces of single-rooted teeth were treated by different methods including (1) conventional hand instruments; (2) hand instruments\\u000a and tetracycline-hydrochloride (Tet-HCl); (3) erbium, chromium:yttrium–scandium–gallium–garnet

  10. High energy resolution with transparent ceramic garnet scintillators

    NASA Astrophysics Data System (ADS)

    Cherepy, N. J.; Seeley, Z. M.; Payne, S. A.; Beck, P. R.; Swanberg, E. L.; Hunter, S.; Ahle, L.; Fisher, S. E.; Melcher, C.; Wei, H.; Stefanik, T.; Chung, Y.-S.; Kindem, J.

    2014-09-01

    Breakthrough energy resolution, R(662keV) < 4%, has been achieved with an oxide scintillator, Cerium-doped Gadolinium Yttrium Gallium Aluminum Garnet, or GYGAG(Ce). Transparent ceramic GYGAG(Ce), has a peak emission wavelength of 550 nm that is better matched to Silicon photodetectors than to standard PMTs. We are therefore developing a spectrometer based on pixelated GYGAG(Ce) on a Silicon photodiode array that can provide R(662 keV) = 3.6%. In comparison, with large 1-2 in3 size GYGAG(Ce) ceramics we obtain R(662 keV) = 4.6% with PMT readout. We find that ceramic GYGAG(Ce) of a given stoichiometric chemical composition can exhibit very different scintillation properties, depending on sintering conditions and post-anneal treatments. Among the characteristics of transparent ceramic garnet scintillators that can be controlled by fabrication conditions are: scintillation decay components and their amplitudes, intensity and duration of afterglow, thermoluminescence glow curve peak positions and amplitudes, integrated light yield, light yield non-proportionality - as measured in the Scintillator Light Yield Non-Proportionality Characterization Instrument (SLYNCI), and energy resolution for gamma spectroscopy. Garnet samples exhibiting a significant fraction of Cerium dopant in the tetravalent valence also exhibit: faster overall scintillation decay, very low afterglow, high light yield, but poor light yield proportionality and degraded energy resolution.

  11. Site-selective couplings in x-ray-detected magnetic resonance spectra of rare-earth-substituted yttrium iron garnets

    NASA Astrophysics Data System (ADS)

    Goulon, J.; Rogalev, A.; Wilhelm, F.; Goujon, G.; Yaresko, A.; Brouder, Ch; Ben Youssef, J.

    2012-06-01

    Site-selective x-ray detected magnetic resonance (XDMR) spectra were recorded in transverse detection geometry on two iron garnet thin films grown by liquid phase epitaxy (LPE) on oriented gadolinium gallium garnet (GGG) substrates: whereas the stoichiometry of the first film corresponded to pure yttrium iron garnet (1 = YIG) used as reference, yttrium was partly substituted with lanthanum and lutetium in the second film (2 = La-Lu-YIG). Surprisingly, the XDMR spectra of film 2 recorded at either the Fe K-edge or the La L3-edge revealed well-resolved structures that had fairly different relative intensity depending on whether we probed the tetrahedral ( {S}_{4} ) sites of iron or the dodecahedral ( {D}_{2} ) sites of lanthanum. The narrow XDMR lines measured at the Fe K-edge also contrast with the broad, foldover distorted lineshapes of the ferrimagnetic resonance spectra measured in the same scan. Further XDMR experiments were carried out with a thin, disc-shaped, single crystal of gadolinium iron garnet (3 = GdIG). At temperatures slightly above the gadolinium ordering temperature (T > TB = 69 K), the Gd L2-edge XDMR spectra were dominated by two well-resolved lines of nearly equal intensities. Similarly, the Fe K-edge XDMR spectra recorded under identical conditions did also split into several narrow lines but of strongly unequal intensity. These results suggest that, in the exchange-enhanced paramagnetic regime, spins precessing at the dodecahedral ( {D}_{2} ) sites of gadolinium do not couple in the same way with spins precessing at either the tetrahedral ( {S}_{4} ) or octahedral ( {S}_{6} ) sites of iron. On the other hand, destructive interferences between modes of opposite helicities were also observed in Fe K-edge XDMR spectra recorded far above the compensation temperature (T ? Tcp = 290 K). This looks like a typical signature of nonlinear four-magnon scattering processes at a very high pumping power.

  12. Light-emitting diodes of 'Warm' white luminescence on the basis of p-n heterostructures of the InGaN/AlGaN/GaN type coated with phosphors made of yttrium-gadolinium garnets

    SciTech Connect

    Soshchin, N. P. [Research Institute 'Platan' (Russian Federation); Galchina, N. A.; Kogan, L. M. [Research and Production Center of Optoelectronic Devices 'OPTEL' (Russian Federation); Shirokov, S. S.; Yunovich, A. E. [Moscow State University, Physical Faculty (Russian Federation)], E-mail: yunovich@phys.msu.ru

    2009-05-15

    Electroluminescence spectra and color characteristics of light-emitting diodes of white luminescence based on p-n heterostructures of the InGaN/AlGaN/GaN type with blue emission ({lambda}{sub max} {approx} 455 nm) coated with phosphors of the type of aluminum-yttrium-gadolinium garnets activated with the Ce{sup 3+} ions are studied. The maximum in the excitation spectra of phosphors varies in the range 460-470 nm. The luminescence spectra of phosphors have the peaks from 530 to 590 nm and a width at half-maximum of intensity from 120 to 135 nm depending of the compound composition. The selection of intensities of blue and yellow-orange bands allows one to shift the coordinates of chromaticity of white light-emitting diodes to the region of 'warm' luminescence with a correlated color temperature to T{sub CC} = 3000 K and maximum luminous efficiency up to 50 lm/W.

  13. Garnet polycrystals

    NASA Astrophysics Data System (ADS)

    Whitney, Donna; Seaton, Nca

    2010-05-01

    Electron backscattered diffraction (EBSD) studies have revealed complex microstructures in garnet, including features developed during crystal growth and/or deformation. New data show that garnets commonly grow as clusters of grains (polycrystals) juxtaposed by high-angle boundaries. Garnet polycrystals may form at any stage of metamorphism following nucleation of garnet: polycrystals may form early as a result of close spacing of nuclei, or later via impingement of larger grains. EBSD analysis of garnets in metamorphic rocks from 9 localities in the US, Canada, Turkey, Iran, and Colombia detected polycrystals at every site. Evidence for internal deformation of garnet was observed in only one sample, a calc-pelite dominated by plagioclase; all other samples are mica schists. Three sites displayed garnet shape-preferred orientation, but none had a crystallographic preferred orientation of garnet. In some samples, polycrystals comprise ~20-30% of garnets analyzed. Some early-coalescing polycrystals exhibit growth zoning concentric about the geometric center of the polycrystal; i.e., zoning is unrelated to the location of internal grain boundaries. In other polycrystals, Fe-Mn-Mg zoning has a different pattern than that of Ca. Some polycrystals are characterized by high-angle misorientation boundaries in special orientations, indicating that these polycrystals are not random clusters of grains. Special boundaries were detected in 0-60% of garnets analyzed. Polycrystal formation may relate to the presence of chemical or textural heterogeneities (e.g. precursor phases, deformation features) that allowed close spacing of garnet nuclei. It is important to recognize polycrystals because internal grain boundaries may affect diffusion pathways and length scales and may facilitate communication of garnet interiors with matrix phases, thereby influencing reaction history and garnet composition and zoning.

  14. Transparent garnet ceramic scintillators for gamma-ray detection

    NASA Astrophysics Data System (ADS)

    Wang, Yimin; Baldoni, Gary; Rhodes, William H.; Brecher, Charles; Shah, Ananya; Shirwadkar, Urmila; Glodo, Jarek; Cherepy, Nerine; Payne, Stephen

    2012-10-01

    Lanthanide gallium/aluminum-based garnets have a great potential as host structures for scintillation materials for medical imaging. Particularly attractive features are their high density, chemical radiation stability and more importantly, their cubic structure and isotropic optical properties, which allow them to be fabricated into fully transparent, highperformance polycrystalline optical ceramics. Lutetium/gadolinium aluminum/gallium garnets (described by formulas ((Gd,Lu)3(Al,Ga)5O12:Ce, Gd3(Al,Ga)5O12:Ce and Lu3Al5O12:Pr)) feature high effective atomic number and good scintillation properties, which make them particularly attractive for Positron Emission Tomography (PET) and other ?- ray detection applications. The ceramic processing route offers an attractive alternative to single crystal growth for obtaining scintillator materials at relatively low temperatures and at a reasonable cost, with flexibility in dimension control as well as activator concentration adjustment. In this study, optically transparent polycrystalline ceramics mentioned above were prepared by the sintering-HIP approach, employing nano-sized starting powders. The properties and microstructures of the ceramics were controlled by varying the processing parameters during consolidation. Single-phase, high-density, transparent specimens were obtained after sintering followed by a pressure-assisted densification process, i.e. hot-isostatic-pressing. The transparent ceramics displayed high contact and distance transparency as well as high light yield as high as 60,000-65,000 ph/MeV under gamma-ray excitation, which is about 2 times that of a LSO:Ce single crystal. The excellent scintillation and optical properties make these materials promising candidates for medical imaging and ?-ray detection applications.

  15. Faraday effect of bismuth iron garnet thin film prepared by mist CVD method

    NASA Astrophysics Data System (ADS)

    Yao, Situ; Sato, Takafumi; Kaneko, Kentaro; Murai, Shunsuke; Fujita, Koji; Tanaka, Katsuhisa

    2015-06-01

    Metastable bismuth iron garnet (BIG, an abbreviation of Bi3Fe5O12), one kind of garnet-type ferrites, is known to manifest very large Faraday rotation as well as low optical absorption in the visible to infrared region. We report on successful synthesis of thin film composed of single-phase BIG epitaxially grown on single-crystalline gadolinium gallium garnet (Gd3Ga5O12, GGG) substrate by using mist chemical vapor deposition (CVD) method, which is an emerging technique for preparation of thin films. The crystal structure, surface morphology, and magnetic, optical and magneto-optical properties of the resultant thin films have been explored. The BIG thin film has a relatively flat surface free from roughness compared to those prepared by other vapor deposition methods. Saturation magnetization is about 1620 G at room temperature, which is close to that expected from the ideal magnetic structure of BIG. The maximum value of Faraday rotation angle reaches 54.3 deg/µm at a wavelength of 424 nm. This value is rather large when compared with those reported for BIG thin films prepared by other techniques. The wavelength dependence of Faraday rotation angle is analyzed well in terms of the crystal electric field (CEF) level schema. Our result suggests that the mist CVD method is a simple and effective technique to synthesize BIG thin film with excellent magneto-optical properties.

  16. Fabrication and characterization of Bismuth-Cerium composite iron garnet epitaxial films for magneto optical applications

    SciTech Connect

    Chandra Sekhar, M.; Singh, Mahi R. [Department of Physics and Astronomy, 1151, Richmond Street, Western University, London, Ontario N6A 3K7 (Canada)

    2012-10-15

    The Bi{sub x}Ce{sub 3-x}Fe{sub 5}O{sub 12} (x = 0.8) epitaxial films of high quality were grown by means of pulsed laser deposition on paramagnetic substrates of Gadolinium Gallium Garnet. We study the modifications of substitutions in the parent garnet Y{sub 3}Fe{sub 5}O{sub 12} that produces a higher magneto-optical response at communication wavelengths. These films displayed a strong in plane textures which are treated in argon as well as reduced atmosphere conditions. The elemental constituents of these films were confirmed by energy dispersive-X ray analysis, elastic recoil detection system, Rutherford backscattering spectroscopy, and X-ray photoelectron spectroscopy measurements. The transmittance spectra were measured and found these films exhibit good transmittance values. The transmittance-spectra were fitted with the theoretical model and the optical constants such as refractive index and absorption edge were evaluated. The highest (negative) Faraday rotation was found for these films treated in the environment of Ar + H{sub 2}. A density matrix theory has been developed for the Faraday rotation and a good agreement between the theory and experiment is found. These epitaxial garnet films can be used in a wide range of frequencies from visible to infrared spectra making them ideal for many magneto optical applications. Therefore, these films may overcome many issues in fabricating all optical isolators which is the viable solution for integrated photonics.

  17. Pulsed laser ablation deposition of yttrium iron garnet and cerium-substituted YIG films

    NASA Astrophysics Data System (ADS)

    Ibrahim, N. B.; Edwards, C.; Palmer, S. B.

    2000-10-01

    Yttrium iron garnet (YIG) thin films were grown on gadolinium gallium garnet substrates using pulsed laser ablation deposition (PLAD) with a XeCl excimer laser. Films were grown up to over 2 ?m thick, however cracking proved to be a problem for films over 1 ?m thick. The lattice parameter(s) of the films and the substrates were measured and indicated that the film/substrate structure was bending to accommodate strain due to the lattice mismatch. The films had saturation magnetisation values close to that of bulk YIG and were isotropic in the film plane. The magnetisation data also indicate stress-induced uniaxial isotropy. The ablation conditions were varied to produce uncracked films with low droplet densities. YIG melts incongruently during the laser ablation process and cone-like structures form on the ablation target lowering the ablation rates. Cerium-substituted YIG films were also grown in both oxygen and argon atmospheres, substituting cerium into YIG increases the lattice parameter and hence reduces the strain. The Ce-YIG film grown in argon was greenish indicating that cerium was in the desired oxidation state.

  18. Gallium and gallium arsenide

    SciTech Connect

    Kramer, D.

    1988-01-01

    As part of the Nation's growing concern with the competitiveness of U.S. firms in the world economy, especially with respect to advanced materials, the Bureau of Mines assessed the actual and potential recovery and manufacturing capabilities for gallium and gallium arsenide (GaAs). GaAs has advanced from a laboratory curiosity to a material with important high-tech applications within only the last few years, and although protected North American gallium supplies are currently considered adequate, consumption could grow to the point that this assessment would need reevaluation.

  19. Cr-doped yttrium gallium garnet laser

    SciTech Connect

    Walling, J. C.; Shand, M. L.

    1984-12-25

    A broadly wavelength-tunable laser is provided which comprises as the laser medium a single crystal of YGG:Cr/sup 3 +/. The laser may be operated over a broad temperature range from cryogenic temperatures to elevated temperatures. Emission is in a spectral range from red to infrared, and the laser is useful in the fields of defense, communications, isotope separation, photo-chemistry, etc.

  20. Gallium complexes and solvent extraction of gallium

    SciTech Connect

    Coleman, J.P.; Graham, C.R.; Monzyk, B.F.

    1988-05-03

    This patent describes a process for recovering gallium from aqueous solutions containing gallium which comprises contacting such a solution with an organic solvent containing at least 2% by weight of a water-insoluble N-organo hydroxamic acid having at least about 8 carbon atoms to extract gallium, and separating the gallium loaded organic solvent phase from the aqueous phase.

  1. Rare-Earth Garnets and Perovskites for Space-Based ADR Cooling at High T and Low H

    NASA Technical Reports Server (NTRS)

    King, T. T.; Rowlett, B. A.; Ramirez, R. A.; Shirron, P. J.; Canavan, E. R.; DiPirro, M. J.; Panek, J. S.; Tuttle, J. G.; Shull, R. D.; Fry, R. A.; Brodeur, Stephen J. (Technical Monitor)

    2001-01-01

    Future NASA satellite detector systems must be cooled to the 0.1 K temperature range to meet the stringent energy resolution and sensitivity requirements demanded by mid-term astronomy missions. The development of adiabatic demagnetization refrigeration (ADR) materials that can efficiently cool from the passive radiative cooling limit of approx. 30 K down to sub-Kelvin under low magnetic fields (H less than or equal to 3 T) would represent a significant improvement in space-based cooling technology. Governed by these engineering goals, our efforts have focused on quantifying the change in magnetic entropy of rare-earth garnets and perovskites. Various compositions within the gadolinium gallium iron garnet solid solution series (GGIG, Gd3Ga(5-x)Fe(x)O12, 0.00 less than or equal to X less than or equal to 5.00) and gadolinium aluminum perovskite (GAP, GdAlO3) have been synthesized via an organometallic complex approach and confirmed with powder x-ray diffraction. The magnetization of the GGIG and GAP materials has been measured as a function of composition (0.00 less than or equal to X less than or equal to 5.00), temperature (2 K less than or equal to T less than or equal to 30 K) and applied magnetic field (0 T less than or equal to H less than or equal to 3 T). The magnetic entropy change (DeltaS(sub mag)) between 0 T and 3 T was determined from the magnetization data. In the GGIG system, DeltaS(sub mag) was compositionally dependent; Fe(sup 3+) additions up to X less than or equal to 2.44 increased DeltaS(sub mag) at T > 5 K. For GAP, DeltaS(sub mag) was similar to that of GGIG, X = 0.00, both in terms of magnitude and temperature dependence at T > 10 K. However, the DeltaS(sub mag) of GAP at T < 10 K was less than the endmember GGIG composition, X = 0.00, and exhibited maximum approx. 5 K.

  2. Nonlinear effects in magnetic garnet films and nonreciprocal optical Bloch oscillations in waveguide arrays

    NASA Astrophysics Data System (ADS)

    Kumar, Pradeep

    This dissertation presents detailed experimental and theoretical investigations of nonlinear and nonreciprocal effects in magnetic garnet films. The dissertation thus comprises two major sections. The first section concentrates on the study of a new class of nonlinear magneto-optic thin film materials possessing strong higher order magnetic susceptibility for nonlinear optical applications. The focus was on enlarging the nonlinear performance of ferrite garnet films by strain generation and compositional gradients in the sputter-deposition growth of these films. Under this project several bismuth-substituted yttrium iron garnet (Bi,Y)3(Fe,Ga)5O12 (acronym as Bi:YIG) films have been sputter-deposited over gadolinium gallium garnet (Gd 3Ga5O12) substrates and characterized for their nonlinear optical response. One of the important findings of this work is that lattice mismatch strain drives the second harmonic (SH) signal in the Bi:YIG films, in agreement with theoretical predictions; whereas micro-strain was found not to correlate significantly with SH signal at the micro-strain levels present in these films. This study also elaborates on the role of the film's constitutive elements and their concentration gradients in nonlinear response of the films. Ultrahigh sensitivity delivered by second harmonic generation provides a new exciting tool for studying magnetized surfaces and buried interfaces, making this work important from both a fundamental and application point of view. The second part of the dissertation addresses an important technological need; namely the development of an on-chip optical isolator for use in photonic integrated circuits. It is based on two related novel effects, nonreciprocal and unidirectional optical Bloch oscillations (BOs), recently proposed and developed by Professor Miguel Levy and myself. This dissertation work has established a comprehensive theoretical background for the implementation of these effects in magneto-optic waveguide arrays. The model systems we developed consist of photonic lattices in the form of one-dimensional waveguide arrays where an optical force is introduced into the array through geometrical design turning the beam sideways. Laterally displaced photons are periodically returned to a central guide by photonic crystal action. The effect leads to a novel oscillatory optical phenomenon that can be magnetically controlled and rendered unidirectional. An on-chip optical isolator was designed based on the unidirectionality of the magneto-opticBloch oscillatory motion. The proposed device delivers an isolation ratio as high as 36 dB that remains above 30 dB in a 0.7 nm wavelength bandwidth, at the telecommunication wavelength 1.55 mum. Slight modifications in isolator design allow one to achieve an even more impressive isolation ratio ~ 55 dB, but at the expense of smaller bandwidth. Moreover, the device allows multifunctionality, such as optical switching with a simultaneous isolation function, well suited for photonic integrated circuits.

  3. Gallium fluoroarsenates.

    PubMed

    Marshall, Kayleigh L; Armstrong, Jennifer A; Weller, Mark T

    2015-07-01

    Six new phases in the gallium-fluoride-arsenate system have been synthesised hydrofluorothermally using a fluoride-rich medium and "HAsF6" (HF?:?AsF5) as a reactant. RbGaF3(H2AsO4), KGaF(H2AsO4) and [piperazine-H2]2[Ga2F8(HAsO4)]·H2O have one dimensional structures, [DABCO-H2]2[Ga4F7O2H(AsO4)2]·4H2O consists of two dimensionally connected polyhedral layers, while GaF(AsO3[OH,F])2 and (NH4)3Ga4F9(AsO4)2 both have three-dimensionally connected polyhedral frameworks. PMID:26095086

  4. Garnets and garnet films: Production and applications. (Latest citations from the US Patent database). Published Search

    SciTech Connect

    Not Available

    1992-12-01

    The bibliography contains citations of selected patents concerning garnet and garnet film fabrication techniques and processes. Polishing and etching of single crystal garnets are described. Applications are discussed, including use of garnets and garnet films in lighting, visual display systems, magnetooptics, superconductors, lasers, bubble memory devices, jewelry, and electronic components. Epitaxial growth of garnets is discussed in a related bibliography. (Contains a minimum of 107 citations and includes a subject term index and title list.)

  5. Gallium nitride optoelectronic devices

    NASA Technical Reports Server (NTRS)

    Chu, T. L.; Chu, S. S.

    1972-01-01

    The growth of bulk gallium nitride crystals was achieved by the ammonolysis of gallium monochloride. Gallium nitride single crystals up to 2.5 x 0.5 cm in size were produced. The crystals are suitable as substrates for the epitaxial growth of gallium nitride. The epitaxial growth of gallium nitride on sapphire substrates with main faces of (0001) and (1T02) orientations was achieved by the ammonolysis of gallium monochloride in a gas flow system. The grown layers had electron concentrations in the range of 1 to 3 x 10 to the 19th power/cu cm and Hall mobilities in the range of 50 to 100 sq cm/v/sec at room temperature.

  6. Faraday Rotation Spectrum of Bismuth-Doped Rare-Earth Iron Garnets for Magneto-Optic Sensor Applications

    NASA Astrophysics Data System (ADS)

    Shinn, Mannix; Wu, Dong Ho; Garzarella, Anthony; Tao, Rongjia

    2014-03-01

    Iron garnet Faraday rotators are a promising sensor material for measuring magnetic fields. The rotator's field sensitivity increases inversely with wavelength and beam path, but so does the insertion loss. We wish to optimize sensor sensitivity by studying the transmission coefficient and Verdet constant over a spectrum from 0.4 to 2 um in samples of bismuth-doped rare-earth iron garnet. Data for two different gallium doped samples will be presented, including data of other magnetic field dependent effects that were observed.

  7. Gallium interactions with Zircaloy 

    E-print Network

    West, Michael Keith

    1998-01-01

    : Nuclear Engineering GALLIUM INTERACTIONS WITH ZIRCALOY A Thesis by MICHAEL KEITH WEST Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: Ron R.... Hart (Chair of Co ittee) Karl T. H g, (Me e Marvin L. Adams (Member) Alan E. Waltar (Head of Department) December 1998 Major Subject: Nuclear Engineering ABSTRACT Gallium Interactions with Zircaloy. (December 1998) Michael Keith West, B. S...

  8. Preventing Supercooling Of Gallium

    NASA Technical Reports Server (NTRS)

    Massucco, Arthur A.; Wenghoefer, Hans M.; Wilkins, Ronnie

    1994-01-01

    Principle of heterogeneous nucleation exploited to prevent gallium from supercooling, enabling its use as heat-storage material that crystallizes reproducibly at its freezing or melting temperature of 29 to 30 degrees C. In original intended application, gallium used as heat-storage material in gloves of space suits. Terrestrial application lies in preparation of freezing-temperature reference samples for laboratories. Principle of heterogeneous nucleation also exploited similarly in heat pipes filled with sodium.

  9. The Magnetocrystalline Anisotropy of Gadolinium

    Microsoft Academic Search

    W. D. Corner; W. C. Roe; K. N. R. Taylor

    1962-01-01

    Measurements of the magnetocrystalline anisotropy constants have been made on a single crystal of gadolinium using a torque magnetometer. The apparatus used is briefly described and the application of corrections for lack of saturation and for a paramagnetic component are explained. Measurements have been made between 37.5 °K and 315 °K and it is found that three constants are required

  10. Eclogites and garnet pyroxenites: Similarities and differences

    NASA Astrophysics Data System (ADS)

    Gonzaga, R. G.; Lowry, D.; Jacob, D. E.; LeRoex, A.; Schulze, D.; Menzies, M. A.

    2010-02-01

    Eclogites and garnet pyroxenites are genetically linked to basaltic precursors. Traditionally garnet pyroxenites are linked to fractionation of basaltic magmas over a range of mantle pressures and more recently they have been implicated in the genesis of ocean islands. In contrast eclogites are linked to the subduction of slab basalt and gabbro precursors which may be hydrothermally altered. Recently this subduction paradigm has been questioned. We present mineralogical, trace element and O isotopic data for eclogites and garnet pyroxenites that reveal some similarities but also important chemical and isotopic differences that support a distinct provenance (i.e., age and process). Continental and oceanic garnet pyroxenites have relatively homogeneous O isotope compositions identical to peridotitic mantle and P-type solid inclusions in diamonds. In contrast on- and off-craton continental eclogites have heterogeneous O isotopes with similarities to E-type solid inclusions in diamonds. This is consistent with garnet pyroxenites being high temperature derivatives of melts in equilibrium with mantle peridotite but requiring eclogites to have a more multi-stage history. This invalidates arguments that eclogites and garnet pyroxenites are identical, and also raises questions about petrogenetic models for OIB production that have an implicit link between eclogite and garnet pyroxenite.

  11. Metals Fact Sheet: Gadolinium GD

    SciTech Connect

    NONE

    1992-10-01

    Gadolinium is a silvery-white, malleable, ductile metallic element used to improve the high-temperature characteristics of iron, chromium, and related metallic alloys. It was named after the French chemist, Gadolin, discoverer of yttrium. This article discusses sources of the element, the world supply and demand, and also a number of applications. With the largest thermal neutron absorption cross section of any element, one of these applications is as a burnable poison in reactors and as neutron absorbers in other nuclear devices.

  12. Gallium phosphide energy converters

    Microsoft Academic Search

    P. E. Sims; L. C. Dinetta; M. A. Goetz

    1995-01-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need

  13. Gallium interactions with Zircaloy

    SciTech Connect

    Woods, A.L. [ed.; West, M.K. [Texas A and M Univ., College Station, TX (United States). Dept. of Nuclear Engineering

    1999-01-01

    This study focuses on the effects of gallium ion implantation into zircaloy cladding material to investigate the effects that gallium may have in a reactor. High fluence ion implantation of Ga ions was conducted on heated Zircaloy-4 in the range of 10{sup 16}--10{sup 18} Ga ions/cm2. Surface effects were studied using SEM and electron microprobe analysis. The depth profile of Ga in the Zircaloy was characterized with Rutherford backscattering and SIMS techniques. Results indicate that the Zirc-4 is little affected up to a fluence of 10{sup 17} Ga ions/cm{sup 2}. After implantation of 10{sup 18} Ga ions/cm{sup 2}, sub-grain features on the order of 2 {micro}m were observed which may be due to intermetallic compound formation between Ga and Zr. For the highest fluence implant, Ga content in the Zirc-4 reached a saturation value of between 30 and 40 atomic %; significant enhanced diffusion was observed but gallium was not seen to concentrate at grain boundaries.

  14. Oxidative dissolution of gallium arsenide and separation of gallium from arsenic

    SciTech Connect

    Coleman, J.P.; Monzyk, B.F.

    1988-07-26

    The method of dissociating gallium arsenide into a gallium-containing component and an arsenic-containing component, is described which comprises contacting the gallium arsenide with an oxidizing agent and a liquid comprising hydroxamic acid to convert the gallium to a gallium-hydroxamic acid complex and to oxidize the arsenic to a positive valence state.

  15. Zinc transmetallation and gadolinium retention after MR imaging: case report.

    PubMed

    Greenberg, Steven A

    2010-12-01

    A patient with chronic zinc poisoning from denture cream retained gadolinium after a magnetic resonance imaging procedure, likely due to transmetallation. During chelation therapy, high levels of gadolinium in excreted urine (up to 89 ?g/d, 29 days after gadolinium administration) were present, indicating that gadolinium had been retained. Almost 2½ years after gadolinium exposure, a 24-hour urine collection indicated that the gadolinium level remained in the elevated range (0.6 ?g/d). This single case report suggests that patients with elevated zinc exposure may be at increased risk of gadolinium retention. PMID:20829541

  16. Rare earth garnet selective emitter

    NASA Technical Reports Server (NTRS)

    Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

    1994-01-01

    Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approximately equal to 0.74, ((4)l(sub 15/2)) - ( (4)l(sub13/2)), for Er-YAG and epsilon(sub lambda) approximately equal to 0.65, ((5)l(sub 7))-((5)l(sub 8)) for Ho-YAG) at excellent candidates for high efficiency selective emitters in the thermophotovoltaics (TPV) systems operating at moderate temperatures (1200-1500K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium (Ho), and erbium (Er) doped YAG thin film selective emitters at 1500 K, and compares those results with the theoretical spectral emittance.

  17. Status of gadolinium enrichment technology at LLNL

    SciTech Connect

    Haynam, C.; Comaskey, B.; Conway, J.; Eggert, J.; Glaser, J.; Ng, E.; Paisner, J.; Solarz, R.; Worden, E.

    1993-01-01

    A method based on,polarization selectivity and three step laser photoionization is presented for separation of the odd isotopes of gadolinium. Measurements of the spectroscopic parameters needed to quantify the excitation pathway are discussed. Model results are presented for the efficiency of photoionization. The vapor properties of electron beam vaporized gadolinium are presented which show dramatic cooling during the expansion of the hot dense vapor into a vacuum. This results in a significant increase in the efficiency of conversion of natural feed into enriched product in the AVLIS process. Production of enriched gadolinium for use in commercial power reactors appears to be economically viable using technology in use at LLNL.

  18. Fundamental studies of the metallurgical, electrical, and optical properties of gallium phosphide and gallium phosphide alloys

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Abstracts, bibliographic data, oral presentations, and published papers on (1) Diffusion of Sulfur in Gallium Phosphide and Gallium Arsenide, and (2) Properties of Gallium Phosphide Schottky Barrier Rectifiers for Use at High Temperature are presented.

  19. Nuclear data for gadolinium production

    SciTech Connect

    Holden, N.E.

    1986-01-01

    There has been a marked increase in requests for neutron cross-section data of the rare-earth isotopes, /sup 152/Gd, /sup 153/Gd, /sup 151/Eu, /sup 152/Eu, /sup 153/Eu, /sup 154/Eu, and /sup 155/Eu because of the use of natural europium-oxide in reactor production of /sup 153/Gd. This gadolinium isotope is needed because of its use as the working ingredient in an advanced medical scanning machine that can detect loss of bone minerals such as calcium, a possible cause of the disease osteoporosis. Hanford's Fast Flux Test Facility plans to begin production of several /sup 153/Gd specimens during this autumn's operating cycle. An analysis of various experiments led to recommended values for the cross sections and resonance integrals, which are displayed and compared with the ENDF/B-V values. The detailed data underlying these recommendations are presented.

  20. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; DiNetta, Louis C.; DuganCavanagh, K.; Goetz, M. A.

    1996-01-01

    Betavoltaic power supplies based on gallium phosphide can supply long term low-level power with high reliability. Results are presented for GaP devices powered by Ni-63 and tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/cm(exp 2) have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. A small demonstration system has been assembled that generates and stores enough electricity to light up an LED.

  1. Gallium Arsenide Domino Circuit

    NASA Technical Reports Server (NTRS)

    Yang, Long; Long, Stephen I.

    1990-01-01

    Advantages include reduced power and high speed. Experimental gallium arsenide field-effect-transistor (FET) domino circuit replicated in large numbers for use in dynamic-logic systems. Name of circuit denotes mode of operation, which logic signals propagate from each stage to next when successive stages operated at slightly staggered clock cycles, in manner reminiscent of dominoes falling in a row. Building block of domino circuit includes input, inverter, and level-shifting substages. Combinational logic executed in input substage. During low half of clock cycle, result of logic operation transmitted to following stage.

  2. High-temperature transport properties of gadolinium

    Microsoft Academic Search

    V. E. Zinovev; L. P. Geld; G. E. Chuprikov; K. I. Epifanova

    1973-01-01

    The electrical resistivity (range 290-1200 deg K) and the thermal ; diffustvity (range 900-1500 deg K) of gadolinium, have been measured and ; correlations are made to carrier scattering mechanisms. (AIP) (auth);

  3. Luminescence and photosensitivity of gadolinium labeled hematoporphyrin

    E-print Network

    Cao, Wenwu

    , as photosensitizer, ratiometric oxygen sensor and MRI contrast agent. The time resolved spectroscopy revealed to be phosphorescent. This phosphorescence is strongly dependent on dissolved oxygen concentration. Its intensity modality, precise evaluation of tissue oxygen and an effective photosensitizer. Gadolinium based

  4. On the origin of pyroxene exsolution topotaxy in majoritic garnets

    Microsoft Academic Search

    J. Zhang; H. Xu; L. Dobrzhinetskaya

    2009-01-01

    The pyroxene exsolution in garnet after majorite from garnet peridotites of Otrøy and Fjørtoft Islands suggests a very deep origin (>350 km) of the rocks. Microstructures and trace element compositions of the exsolved pyroxenes and garnets indicate that these ultra-deep mantle rocks may have experienced a complex multiple stage exhumation process. The interstitial pyroxenes were exsolved during the Archean upwelling

  5. Magnetic volumetric hologram memory with magnetic garnet.

    PubMed

    Nakamura, Yuichi; Takagi, Hiroyuki; Lim, Pang Boey; Inoue, Mitsuteru

    2014-06-30

    Holographic memory is a promising next-generation optical memory that has a higher recording density and a higher transfer rate than other types of memory. In holographic memory, magnetic garnet films can serve as rewritable holographic memory media by use of magneto-optical effect. We have now demonstrated that a magnetic hologram can be recorded volumetrically in a ferromagnetic garnet film and that the signal image can be reconstructed from it for the first time. In addition, multiplicity of the magnetic hologram was also confirmed; the image could be reconstructed from a spot overlapped by other spots. PMID:24977893

  6. Gallium Safety in the Laboratory

    SciTech Connect

    Cadwallader, L.C.

    2003-05-07

    A university laboratory experiment for the US Department of Energy magnetic fusion research program required a simulant for liquid lithium. The simulant choices were narrowed to liquid gallium and galinstan (Ga-In-Sn) alloy. Safety information on liquid gallium and galinstan were compiled, and the choice was made to use galinstan. A laboratory safety walkthrough was performed in the fall of 2002 to support the galinstan experiment. The experiment has been operating successfully since early 2002.

  7. Gallium Safety in the Laboratory

    SciTech Connect

    Lee C. Cadwallader

    2003-06-01

    A university laboratory experiment for the US Department of Energy magnetic fusion research program required a simulant for liquid lithium. The simulant choices were narrowed to liquid gallium and galinstan (Ga-In-Sn) alloy. Safety information on liquid gallium and galinstan were compiled, and the choice was made to use galinstan. A laboratory safety walkthrough was performed in the fall of 2002 to support the galinstan experiment. The experiment has been operating successfully since early 2002.

  8. Intensities of hypersensitive transitions in garnet crystals doped with Er3+ ions

    NASA Astrophysics Data System (ADS)

    Bol'Shakova, E. V.; Malov, A. V.; Ryabochkina, P. A.; Ushakov, S. N.; Nishchev, K. N.

    2011-06-01

    We examine the oscillator strengths and the intensity parameters ? t ( t = 2, 4, 6) of yttrium-aluminum, scandium-containing, and gallium garnet crystals doped with Er3+ ions. A comparative analysis of the oscillator strengths and the intensity parameters ? t ( t = 2, 4, 6) of garnets with different contents of Al3+ and Sc3+ ions (Gd2.4Er0.5Sc1.8Al3.3O12, Gd2.4Er0.5Sc1.9Al3.2O12, Gd2.4Er0.5Sc2.0Al3.1O12) is performed, as a result of which the oscillator strengths and the intensity parameters ? t ( t = 2, 4, 6) of these crystals are shown to have close values. We find that Ca3(NbGa)5O12 crystals doped with Er3+ ions are characterized by highest values of the oscillator strengths for hypersensitive transitions and of the intensity parameter ?2 of Er3+ ions compared to the values of these quantities in the examined garnet crystals, which is determined by the fact that the symmetry of the local environment of Er3+ ions in these crystals is C 1, C 2, or C 2?. We reveal that, as the concentration of Er3+ ions in these crystals increases from 1 to 39 at %, both the oscillator strength of the hypersensitive transition 4 I 15/2 ? 2 H 11/2 of Er3+ ions and their intensity parameter ?2 tend to decrease, which can be related to an increase in the relative fraction of Er3+ ions with higher symmetry of the local environment.

  9. Gallium oxide and gadolinium gallium oxide insulators on Si ?-doped GaAs/AlGaAs heterostructures

    NASA Astrophysics Data System (ADS)

    Paterson, G. W.; Longo, P.; Wilson, J. A.; Craven, A. J.; Long, A. R.; Thayne, I. G.; Passlack, M.; Droopad, R.

    2008-11-01

    Test devices have been fabricated on two specially grown GaAs/AlGaAs wafers with 10 nm thick gate dielectrics composed of either Ga2O3 or a stack of Ga2O3 and Gd0.25Ga0.15O0.6. The wafers have two GaAs transport channels either side of an AlGaAs barrier containing a Si ?-doping layer. Temperature dependent capacitance-voltage (C-V) and current-voltage (I-V) studies have been performed at temperatures between 10 and 300 K. Bias cooling experiments reveal the presence of DX centers in both wafers. Both wafers show a forward bias gate leakage that is by a single activated channel at higher temperatures and by tunneling at lower temperatures. When Gd0.25Ga0.15O0.6 is included in a stack with 1 nm of Ga2O3 at the interface, the gate leakage is greatly reduced due to the larger band gap of the Gd0.25Ga0.15O0.6 layer. The different band gaps of the two oxides result in a difference in the gate voltage at the onset of leakage of ˜3 V. However, the inclusion of Gd0.25Ga0.15O0.6 in the gate insulator introduces many oxide states (?4.70×1012 cm-2). Transmission electron microscope images of the interface region show that the growth of a Gd0.25Ga0.15O0.6 layer on Ga2O3 disturbs the well ordered Ga2O3/GaAs interface. We therefore conclude that while including Gd0.25Ga0.15O0.6 in a dielectric stack with Ga2O3 is necessary for use in device applications, the inclusion of Gd decreases the quality of the Ga2O3/GaAs interface and near interface region by introducing roughness and a large number of defect states.

  10. Experimental tests of garnet peridotite oxygen barometry

    NASA Astrophysics Data System (ADS)

    Gudmundsson, G.; Wood, B. J.

    1995-02-01

    We have performed experiments aimed at testing the calibration of oxygen barometers for the garnet peridotite [garnet (Gt)-olivine (Ol)-orthopyroxene (Opx)] phase assemblage. These involved equilibrating a thin layer of garnet sandwiched between layers of olivine and orthopyroxene at 1300° C and 25 35 kbar for 1 7 days. Oxygen fugacity was controlled (but not buffered) by using inner capsules of Fe Pt alloy or graphite or molybdenum sealed in welded Pt outer capsules. Post-experiment measurement of f O2 was made by determining the compositions of Pt Fe alloy sensors at the interface between garnet and olivine+orthopyroxene layers. The composition of alloy in equilibrium with olivine+orthopyroxene was approached from Fe-oversaturated and Fe-undersaturated conditions in the same experiment with, in general, excellent convergence. Product phase compositions were determined by electron microprobe and a piece of the garnet layer saved for 57Fe Mössbauer spectroscopy. The latter gave the Fe3+ content of the garnet at the measured P-T-f O2 conditions. Approach to equilibrium was checked by observed shifts in Fe3+ content and by the approach of garnet-olivine Fe Mg partitioning to the expected value. The compositions of the phases were combined with mixing properties and thermodynamic data to calculate an apparent f O2 from two possible garnet oxybarometers:- 2Ca3Fe2Si3O12Gt1+2Mg3Al2Si3O12Gt+4FeSiO3Opx=2Ca3Al2Si3O12Gt+8FeSi0.5O2Ol+6MgSiO3Opx+O2 (1) and 2Fe3Fe2Si3O12Gt=8FeSi0.5O2Ol+2FeSiO3Opx+O2(2) Comparison of calculated f O2s with those measured by the Pt-Fe sensors demonstrated that either barometer gives the correct answer within the expected uncertainty. Data from the first (Luth et al. 1990) has an uncertainty of about 1.6 log f O2 units, however, while that from equilibrium (2) (Woodland and O’Neill 1993) has an error of +/- 0.6 log units, comparable to that of the spinel peridotite oxybarometer. We therefore conclude that equilibrium (2) may be used to calculate the f O2 recorded by garnet peridotites with an uncertainty of about +/- 0.6 log units, providing the potential to probe the oxidation environment of the deep continental lithosphere. Preliminary application based on data from Luth et al. (1990) indicates that garnet peridotite xenoliths from Southern Africa record oxygen fugacities about 3.0 log units below the FMQ (fayalite-magnetite-quartz) buffer. These are substantially more reducing conditions than those recorded by continental spinel lherzolites which typically give oxygen fugacities close to FMQ (Wood et al. 1990).

  11. Potential effects of gallium on cladding materials

    Microsoft Academic Search

    D. F. Wilson; E. C. Beahm; T. M. Besmann; J. H. DeVan; J. R. DiStefano; U. Gat; S. R. Greene; P. L. Rittenhouse; B. A. Worley

    1997-01-01

    This paper identifies and examines issues concerning the incorporation of gallium in weapons derived plutonium in light water reactor (LWR) MOX fuels. Particular attention is given to the more likely effects of the gallium on the behavior of the cladding material. The chemistry of weapons grade (WG) MOX, including possible consequences of gallium within plutonium agglomerates, was assessed. Based on

  12. Structure of dental gallium alloys.

    PubMed

    Herø, H; Simensen, C J; Jørgensen, R B

    1996-07-01

    The interest in gallium alloys as a replacement for amalgam has increased in recent years due to the risk of environmental pollution from amalgam. Alloy powders with compositions close to those for alloys of amalgam are mixed with a liquid gallium alloy. The mix is condensed into a prepared cavity in much the same way as for amalgam. The aim of the present work was to study the structure of: (1) two commercial alloy powders containing mainly silver, tin and copper, and (2) the phases formed by mixing these powders with a liquid alloy of gallium, indium and tin. One of the alloy powders contained 9 wt% palladium. Cross-sections of cylindrical specimens made by these gallium mixes were investigated by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Discrete grains of the following phases were found to be present in both gallium alloys: hexagonal Ag2Ga, tetragonal Cu(Pd)Ga2, cubic Ag9In4 and tetragonal beta-Sn. Indications of hexagonal or orthorhombic Ag2Sn were found in the remaining, unreacted alloy particles. In the palladium-containing alloy the X-ray reflections indicate a minor fraction of cubic Cu9Ga4 in addition to the Cu(Pd)Ga2 phase. Particles of beta-Sn are probably precipitated because Sn-Ga phases cannot be formed according to the binary phase diagram. PMID:8805980

  13. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

    1995-01-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  14. Gallium phosphide energy converters

    NASA Astrophysics Data System (ADS)

    Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

    1995-10-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  15. Gallium phosphide energy converters

    SciTech Connect

    Sims, P.E.; Dinetta, L.C.; Goetz, M.A.

    1995-10-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp {minus}17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  16. Investigation of spiral bending of straight Czochralski grown dysprosium gallium aluminium garnet crystals

    Microsoft Academic Search

    V. V. Kochurikhin; K. Shimamura; T. Fukuda

    1996-01-01

    Dy3(Ga1 ? xAlx)5O12 pseudo-binary single crystals were grown by the Czochralski method. The influence of Al3+ ions on the spiral bending was investigated. Effective suppression of the spiral symptoms takes place at x = 0.4. In the case of x = 0?0.2 the spiral symptoms were observed in the tail part of crystals. In the case of x = 0.6

  17. Wavelength dependence of magneto-optic properties of terbium gallium garnet ceramics.

    PubMed

    Slezak, Ondrej; Yasuhara, Ryo; Lucianetti, Antonio; Mocek, Tomas

    2015-05-18

    The wavelength dependence of magneto-optic properties of TGG ceramics, including the Verdet constant, has been investigated experimentally. The previously obtained Verdet constant of 36.4 rad/Tm for 1064 nm wavelength and 139.6 rad/Tm for 633 nm are in good agreement with presented white light measurements . The comparison with previously reported Verdet constant and absorption coefficient values for TGG single crystal has shown very similar results. These results lead to the conclusion that TGG ceramics is a very good alternative to TGG single crystal and is a powerful approach for realizing large-aperture optical isolators which are required in high-average-power laser systems. PMID:26074614

  18. Cryogenic temperature characteristics of Verdet constant on terbium gallium garnet ceramics.

    PubMed

    Yasuhara, Ryo; Tokita, Shigeki; Kawanaka, Junji; Kawashima, Toshiyuki; Kan, Hirofumi; Yagi, Hideki; Nozawa, Hoshiteru; Yanagitani, Takagimi; Fujimoto, Yasushi; Yoshida, Hidetsugu; Nakatsuka, Masahiro

    2007-09-01

    As the first demonstration of Faraday effect in a TGG ceramics, its Verdet constant at 1053 nm is evaluated to be 36.4 rad/Tm at room temperature which is same as that of the single crystal. In addition, the temperature dependence of Verdet constant is obtained experimentally. At liquid helium temperature, it is 87 times greater than that at room temperature. PMID:19547482

  19. Large-aperture Faraday isolator based on a terbium gallium garnet crystal.

    PubMed

    Mironov, E A; Zheleznov, D S; Starobor, A V; Voitovich, A V; Palashov, O V; Bulkanov, A M; Demidenko, A G

    2015-06-15

    Unique Faraday isolator based on a TGG single crystal with aperture diameter of 40 mm for high average power lasers has been fabricated and investigated experimentally. The device provides a stable isolation ratio over 30 dB for large-radius laser beams with kilowatt average power radiation typical for high-power applications. PMID:26076264

  20. A FETISH for gallium arsenide

    SciTech Connect

    Barron, A.R. [Rice Univ., Houston, TX (United States)

    1996-12-31

    An overview of the development of a new dielectric material, cubic-GaS, from the synthesis of new organometallic compounds to the fabrication of a new class of gallium arsenide based transistor is presented as a representative example of the possibility that inorganic chemistry can directly effect the development of new semiconductor devices. The gallium sulfido compound [({sup t}Bu)GaS]{sub 4}, readily prepared from tri-tert-butyl gallium, may be used as a precursor for the growth of GaS thin films by metal organic chemical vapor deposition (MOCVD). Photoluminescence and electronic measurements indicate that this material provides a passivation coating for GaAs. Furthermore, the insulating properties of cubic-GaS make it suitable as the insulating gate layer in a new class of GaAs transistor: a field effect transistor with a sulfide heterojunction (FETISH).

  1. A toxicological study of gadolinium nitrate

    SciTech Connect

    London, J.E.

    1988-05-01

    The sensitization study in the guinea pig did not show gadolinium nitrate to have potential sensitizing properties. Skin application studies in the rabbit demonstrated that it was cutaneously a severe irritant. This material was considered an irritant in the rabbit eye application studies. 3 refs., 1 tab.

  2. Renal amyloidosis. Evaluation by gallium imaging

    SciTech Connect

    Lee, V.W.; Skinner, M.; Cohen, A.S.; Ngai, S.; Peng, T.T.

    1986-09-01

    A study has been performed to evaluate the efficacy of gallium imaging in the detection of renal amyloidosis. Ten of the 11 patients who had biopsy-proven renal amyloidosis demonstrated marked uptake in both kidneys. One patient revealed moderate gallium uptake in his kidneys. None of the patients had underlying renal or extrarenal pathology other than amyloidosis, which could account for renal gallium uptake (renal infection, neoplasm, hepatic failure or frequent blood transfusions). Four patients also had extrarenal foci of abnormal gallium uptake, suggesting other sites of amyloid deposits. Our data strongly suggest that gallium imaging has a high sensitivity for detection of renal amyloidosis. Its specificity is enhanced significantly by careful review of the clinical history to exclude other known causes of renal gallium uptake. Potentially, gallium imaging may be used to monitor the progress of patients under experimental therapy.

  3. Potential effects of gallium on cladding materials

    SciTech Connect

    Wilson, D.F.; Beahm, E.C.; Besmann, T.M.; DeVan, J.H.; DiStefano, J.R.; Gat, U.; Greene, S.R.; Rittenhouse, P.L.; Worley, B.A.

    1997-10-01

    This paper identifies and examines issues concerning the incorporation of gallium in weapons derived plutonium in light water reactor (LWR) MOX fuels. Particular attention is given to the more likely effects of the gallium on the behavior of the cladding material. The chemistry of weapons grade (WG) MOX, including possible consequences of gallium within plutonium agglomerates, was assessed. Based on the calculated oxidation potentials of MOX fuel, the effect that gallium may have on reactions involving fission products and possible impact on cladding performance were postulated. Gallium transport mechanisms are discussed. With an understanding of oxidation potentials and assumptions of mechanisms for gallium transport, possible effects of gallium on corrosion of cladding were evaluated. Potential and unresolved issues and suggested research and development (R and D) required to provide missing information are presented.

  4. Study of etched (210)-oriented thin garnet films

    NASA Astrophysics Data System (ADS)

    Tkachuk, S.; Bowen, D.; Nistor, I.; Krafft, C.; Mayergoyz, I.

    2008-04-01

    The study of BiPrGdLu garnet films epitaxially grown on (210)-oriented substrates for use as magneto-optical imagers is reported. These garnet films exhibit the phenomena of easy magnetization plane which makes them attractive in imaging applications. It is demonstrated that the thickness reduction of garnet films through chemical etching enhances the clarity and spatial resolution of magneto-optical imaging.

  5. Pressure-induced diffusion in natural garnets

    NASA Astrophysics Data System (ADS)

    Floess, David; Vrijmoed, Johannes; Baumgartner, Lukas; Podladchikov, Yuri

    2015-04-01

    Recent efforts in metamorphic petrology suggest that significant pressure gradients exist on the grain-scale and provide tools for its quantification [1,2]. Here we propose that pressure gradients around coesite inclusions induced diffusion of major elements within garnet crystals upon exhumation. This is based on the fact that the molar mass of garnet endmembers vary between 403 and 497 g/mol, thus up to 23 %. Whiteschists from the Dora Maira Massive in the Western Alps underwent eclogite facies metamorphism (3.3-4.3 GPa, 720-780 °C) during the Alpine event at 35 Ma [3]. Coesite included in garnet (py0.96gr0.02alm0.02) during the HP stage was partially transformed to quartz during the subsequent, rapid exhumation (from 3.5 to 1 GPa within 2 Ma [4]). Coesite is preserved by maintaining a high pressure on the inclusion wall due to the large volume change of the phase transition. The surface of the host garnet experiences a lower pressure controlled by the exhumation P-T path. This pressure difference should induce diffusion of major elements in the garnet surrounding the inclusion. Element distribution maps show well-defined Fe-rich, Ca-poor halos surrounding the coesite-inclusions. The observed diffusion profiles are in agreement with predictions, assuming a positive ?P around the inclusions. The results are based on thermodynamic equilibrium calculations assuming heterogeneous pressure [5]. Hence, the observed profiles are interpreted as an equilibrium state reflecting the pressure (stress) distribution within the crystal and can be used as tool to constrain the exhumation path. Understanding the effect of pressure gradients on diffusion and, alternatively, the generation of pressure due to relaxation of chemical gradients by diffusion, is crucial for interpreting P-T-t paths of zoned minerals correctly. [1] Baumgartner et al. (2010), GSA meeting Denver. [2] Taj?manová et al. (2014) CMP 32, 195-207. [3] Compagnoni & Rolfo (2003), UHP Metamorphism - EMU notes 5. [4] Rubatto & Hermann (2001), Geology 29, 3-6. [5] Vrijmoed & Podladchikov (submitted).

  6. Rare earth element fractionation in magmatic Ca-rich garnets

    NASA Astrophysics Data System (ADS)

    Scheibner, Birgit; Wörner, Gerhard; Civetta, Lucia; Stosch, Heinz-Günter; Simon, Klaus; Kronz, Andreas

    2007-07-01

    Igneous garnets have the potential to strongly fractionate rare earth elements (REE). Yet informations on partition coefficients are very scant, and criteria for distinguishing between hydrothermal and magmatic garnets are ambiguous. To fill this gap, we present trace element and isotopic data for two types of Ca-rich garnets from phonolites (Mt. Somma-Vesuvius). Both Ca-garnet populations are different in their style and dynamics of fractionation: one population is progressively strongly depleted in HREE from core to rim, reflecting REE fractionation in the host phonolite via earlier-crystallized garnets. Such examples for extreme changes in HREE in garnets are only known for hydrothermal grandites by REE-bearing fluids. The second garnet population is homogeneous and formed in a closed system. Near-flat patterns between Sm and Lu confirm experimental data indicating lower D(Sm)/ D(Lu) for Ca-rich garnets than for e.g. pyrope-rich garnets. It follows: D Grt/PhMelt for La = 0.5, Sm = 48 and Yb = 110.

  7. P-type gallium nitride

    DOEpatents

    Rubin, M.; Newman, N.; Fu, T.; Ross, J.; Chan, J.

    1997-08-12

    Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5{times}10{sup 11} /cm{sup 3} and hole mobilities of about 500 cm{sup 2} /V-sec, measured at 250 K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al. 9 figs.

  8. Gallium scan in intracerebral sarcoidosis

    SciTech Connect

    Makhija, M.C.; Anayiotos, C.P.

    1981-07-01

    Sarcoidosis involving the nervous system probably occurs in about 4% of patients. The usefulness of brain scintigraphy in these cases has been suggested. In this case of cerebral sarcoid granuloma, gallium imaging demonstrated the lesion before treatment and showed disappearance of the lesion after corticosteroid treatment, which correlated with the patient's clinical improvement.

  9. Significance of hydrous silicate lamellae in pyrope-rich garnets from the Garnet Ridge in the Colorado Plateau

    NASA Astrophysics Data System (ADS)

    Ogasawara, Y.; Sakamaki, K.; Sato, Y.

    2014-12-01

    Pyrope-rich garnets originated from the upper mantle underneath the Colorado Plateau occur at the Garnet Ridge. These garnets contain the following lamellae of hydrous and anhydrous minerals; Rt, Ilm, crichtonites, Cr-Spl, Amp, Cpx, Chl, rarely Apt, srilankite and carmichealite. The origin of these lamellae in the garnets is controversial; exsolved origin or epitaxial growth. We emphasize here the close relations between the presence of hydrous lamellae and the OH concentrations in the host garnets. Lamella phases were identified with a standard-less quantitative EDS system and a laser Raman spectrometer with Ar+ laser (514.5 nm). OH concentrations in garnets were quantitated on the basis of IR absorption spectra of garnet by micro FT-IR method using IR absorption coefficient (8770 L/mol/cm2, Katayama et al., 2006). Pyrope-rich reddish brown garnet (group B by Sato et al., AGU2014F) has large variations of major chemical compositions (Prp: 49-76, Alm: 6-43, Grs: 6-26 mol%), and OH contents (2-177 ppm wt. H2O). Among this group garnets, Ca-rich ones (Prp: 49-66; Alm: 18-28; Grs: 16-26 mol%) have lamellae of both hydrous (Amp and Chl) and anhydrous (Rt, Ilm, and Cpx) minerals. Amp and Chl lamellae are pargasitic amphibole and clinochlore, respectively, and their host garnets contain significantly low amounts of OH (2-42 ppm). Cr and pyrope-rich garnet (group A by Sato et al., AGU2014F) has chemical compositions of Prp: 67-74, Alm: 13-18, Grs: 7-11 mol% with Cr2O3 up to 5.9 wt.%, and contains lamellae of anhydrous minerals (Rt, Ilm, crichtonites, and Cr-Spl). The host garnet with these anhydrous lamellae contains a little higher OH ranging 24 to 115 ppm. Summarizing the present results, the OH contents of the host garnets depend on the presence of hydrous silicate lamella phase; OH in the garnet with hydrous silicate lamellae is lower than that in the garnet with anhydrous lamellae. The precursor OH incorporated in the host garnet structure was exsolved as hydrous silicate lamellae.

  10. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Copper gallium indium selenide. 721.10391...Chemical Substances § 721.10391 Copper gallium indium selenide. (a) Chemical...The chemical substance identified as copper gallium indium selenide (PMN...

  11. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Copper gallium indium selenide. 721.10391...Chemical Substances § 721.10391 Copper gallium indium selenide. (a) Chemical...The chemical substance identified as copper gallium indium selenide (PMN...

  12. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Copper gallium indium selenide. 721.10391...Chemical Substances § 721.10391 Copper gallium indium selenide. (a) Chemical...The chemical substance identified as copper gallium indium selenide (PMN...

  13. Gallium nitride electronics

    NASA Astrophysics Data System (ADS)

    Rajan, Siddharth; Jena, Debdeep

    2013-07-01

    In the past two decades, there has been increasing research and industrial activity in the area of gallium nitride (GaN) electronics, stimulated first by the successful demonstration of GaN LEDs. While the promise of wide band gap semiconductors for power electronics was recognized many years before this by one of the contributors to this issue (J Baliga), the success in the area of LEDs acted as a catalyst. It set the field of GaN electronics in motion, and today the technology is improving the performance of several applications including RF cell phone base stations and military radar. GaN could also play a very important role in reducing worldwide energy consumption by enabling high efficiency compact power converters operating at high voltages and lower frequencies. While GaN electronics is a rapidly evolving area with active research worldwide, this special issue provides an opportunity to capture some of the great advances that have been made in the last 15 years. The issue begins with a section on epitaxy and processing, followed by an overview of high-frequency HEMTs, which have been the most commercially successful application of III-nitride electronics to date. This is followed by review and research articles on power-switching transistors, which are currently of great interest to the III-nitride community. A section of this issue is devoted to the reliability of III-nitride devices, an area that is of increasing significance as the research focus has moved from not just high performance but also production-worthiness and long-term usage of these devices. Finally, a group of papers on new and relatively less studied ideas for III-nitride electronics, such as interband tunneling, heterojunction bipolar transistors, and high-temperature electronics is included. These areas point to new areas of research and technological innovation going beyond the state of the art into the future. We hope that the breadth and quality of articles in this issue will make it an excellent reference for newcomers and experienced researchers in this field for several years. We thank Alice Malhador at IOP Publishing for her constant encouragement and guidance in putting together this special issue on GaN electronics.

  14. Garnet geotherms: Pressure-temperature data from Cr-pyrope garnet xenocrysts in volcanic rocks

    Microsoft Academic Search

    Chris G. Ryan; William L. Griffin; Norman J. Pearson

    1996-01-01

    The temperatures and pressures of equilibration of single peridotitic garnet xenocrysts are estimated using a combination of major- and trace-element data, determined using electron mi- croprobe (EMP) and proton induced X ray emission (PIXE). This new method enables the use of xenocrysts found in kimberlites and other volcanic rocks to determine the local paleogeotherm at the time of eruption of

  15. Elastic moduli of pyrope rich garnets

    NASA Astrophysics Data System (ADS)

    Pandey, B. K.; Pandey, A. K.; Singh, C. K.

    2013-06-01

    The elastic properties of minerals depend on its composition, crystal structure, temperature and level of defects. The elastic parameters are important for the interpretation of the structure and composition of the garnet rich family. In present work we have calculated the elastic moduli such as isothermal bulk modulus, Young's modulus and Shear modulus over a wide range of temperature from 300 K to 1000 K by using Birch EOS and Poirrier Tarantola equation of state. The obtained results are compared with the experimental results obtained by measuring the elastic moduli of single crystal. The calculated results show that the logarithmic isothermal EOS does not cooperate well with experimental results.

  16. Majorite Garnet and Lithosphere Evolution: Kaapvaal Craton

    NASA Astrophysics Data System (ADS)

    Griffin, W. L.; Tessalina, S.; O'Reilly, S. Y.

    2013-12-01

    The uppermost 50-70 km of the subcontinental lithospheric mantle (SCLM) beneath the Kaapvaal Craton (S. Africa) consists largely of highly-depleted chromite harzburgites. These rocks are understudied, mainly because of their uniformity and their lack of indicator minerals such as garnet and clinopyroxene (cpx). Kimberlite-borne xenoliths of these rocks contain rare volumes of cpx-spinel (modal 76/24) symplectite, with smooth grain boundaries; many studies have suggested that these might represent low-pressure breakdown products of garnet (majorite + olivine ? cpx + spinel). Our reconstruction of a suite of these grains, using element mapping and EMP analysis of constituent minerals, gives a majoritic garnet with mean composition 21.8% CaO, 15.8% Cr2O3, 9.22% Al2O3, Si=3.118, mg#=0.93. The majorite contents suggest formation at depths of 250-280 km. Ni contents imply temperatures ?1500 °C, but have large uncertainties related to the subtraction of olivine (ca 20%) during the reconstruction calculation. LAM-ICPMS analyses show strongly sinuous REE patterns with CN Dy/Lu <0.1 and Ce/Dy >100. Most analyses have negative Eu anomalies, consistent with chromite compositions that indicate strongly reducing conditions (?fO2(FMQ) = -4 to -5). Melt modeling suggests that the harzburgites are products of 30-40% melting of asthenospheric mantle at 250 km depth, leaving residues of ol+opx+chromite. The presence of the majorites and their overall LREE enrichment are ascribed to the introduction of carbonatitic metasomatic fluids, similar to those recorded by diamond-inclusions (subcalcic garnets), shortly after the depletion. We suggest that the melting, the metasomatism and the ultimate breakdown of the majorite track a process of mantle upwelling, with melt-extraction at depth providing the buoyancy that allowed the residual harzburgites to rise to shallow levels and stabilize the SCLM. Os-isotope analyses of sulfides associated with the majorites give TRD = 2.5-3.4 Ga, suggesting that this process was part of the major mantle overturn(s) that produced most of the world's cratonic SCLM [1]. [1] Griffin et al. 2013. Lithos (in press)

  17. The Garnet to Majorite Transformation in Mafic Compositions

    NASA Technical Reports Server (NTRS)

    Xirouchakis, D.; Draper, David S.; Agee, C. B.

    2002-01-01

    The garnet to majorite transformation in mafic compositions is controlled by bulk composition and the presence of silicate melt, clinopyroxene, and silicate perovskite as well as pressure. Thus, the use of empirical geobarometers based on garnet Si(4+) and/or [Al(3+) +/- Cr(3+)] (p.f.u) seems unjustified. Additional information is contained in the original extended abstract.

  18. Garnet megacrysts of the Williams diatremes, north-central Montana.

    USGS Publications Warehouse

    McGee, E.S.

    1986-01-01

    The physical characteristics of garnet megacrysts from the Williams diatremes are described, analysed and compared with other garnet megacryst suites. The only correlation found between the physical characteristics and the composition of the megacrysts related deep-red colour to high Cr content.-J.A.Z.

  19. Imaging capabilities of etched (100) and (210) garnet films

    NASA Astrophysics Data System (ADS)

    Tkachuk, S.; Bowen, D.; Krafft, C.; Mayergoyz, I. D.

    2009-04-01

    Imaging capabilities of etched (100) and (210) oriented garnet films are studied and compared. It is demonstrated that the etching of out-of-plane (100) garnet films may result in drastic reduction in saturation fields. Concurrently, the appreciable increase in contrast and resolution of images produced by the etched films has been observed.

  20. Measurement of arsenic and gallium content of gallium arsenide semiconductor waste streams by ICP-MS

    Microsoft Academic Search

    Keith W. Torrance; Helen E. Keenan; Andrew S. Hursthouse; David Stirling

    2010-01-01

    The chemistry of semiconductor wafer processing liquid waste, contaminated by heavy metals, was investigated to determine arsenic content. Arsenic and gallium concentrations were determined for waste slurries collected from gallium arsenide (GaAs) wafer processing at three industrial sources and compared to slurries prepared under laboratory conditions. The arsenic and gallium content of waste slurries was analyzed using inductively coupled plasma

  1. Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system

    E-print Network

    Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system Kangkang, University of Michigan, Ann Arbor, MI 48109, U.S.A. ABSTRACT Ferromagnetic delta-phase manganese gallium to their potential for novel spintronics applications such as spin light-emitting diodes[1] . Delta phase manganese

  2. Magnetic Properties of Gadolinium Ortho-Aluminate

    Microsoft Academic Search

    J. D. Cashion; A. H. Cooke; T. L. Thorp; M. R. Wells

    1970-01-01

    An account is given of specific heat, magnetic susceptibility and magnetic moment measurements on gadolinium ortho-aluminate, GdAlO3, at temperatures in the liquid helium range. This compound orders antiferromagnetically at 3.87 K. In the antiferromagnetic state, its properties can be accounted for satisfactorily as those of an array of S-state magnetic ions with isotropic magnetic properties, coupled together by exchange interaction

  3. Chemistry and mineralogy of garnet pyroxenites from Sabah, Malaysia

    USGS Publications Warehouse

    Morgan, B.A.

    1974-01-01

    Garnet pyroxenites and corundum-garnet amphibolites from the Dent peninsula of eastern Sabah (North Borneo) occur as blocks in a slump breccia deposit of late Miocene age. The earliest formed minerals include pyrope-almandine garnet, tschermakitic augite, pargasite, and rutile. Cumulate textures are present in two of the six specimens studied. The earlier fabric has been extensively brecciated and partly replaced by plagioclase, ilmenite, and a fibrous amphibole. The bulk composition and mineralogy of these rocks are similar to those of garnet pyroxenite lenses within ultramafic rocks. Estimated temperature and pressure for the origin of the Sabah garnet pyroxenites is 850??150?? C and 19??4 kbar. ?? 1974 Springer-Verlag.

  4. Epitaxial Deposition Of Germanium Doped With Gallium

    NASA Technical Reports Server (NTRS)

    Huffman, James E.

    1994-01-01

    Epitaxial layers of germanium doped with gallium made by chemical vapor deposition. Method involves combination of techniques and materials used in chemical vapor deposition with GeH4 or GeCl4 as source of germanium and GaCl3 as source of gallium. Resulting epitaxial layers of germanium doped with gallium expected to be highly pure, with high crystalline quality. High-quality material useful in infrared sensors.

  5. Gadolinium and nephrogenic systemic fibrosis: an update.

    PubMed

    Weller, Alex; Barber, Joy L; Olsen, Oystein E

    2014-10-01

    Nephrogenic systemic fibrosis (NSF) is a multisystem disease seen exclusively in patients with renal impairment. It can be severely debilitating and sometimes fatal. There is a strong association with gadolinium-based contrast agents used in magnetic resonance imaging (MRI). Risk factors include renal impairment and proinflammatory conditions, e.g. major surgery and vascular events. Although there is no single effective treatment for NSF, the most successful outcomes are seen following restoration of renal function, either following recovery from acute kidney injury or following renal transplantation. There have been ten biopsy-proved pediatric cases of NSF, with no convincing evidence that children have a significantly altered risk compared with the adult population. After implementation of guidelines restricting the use of gadolinium-based contrast agents in at-risk patients, there has been a sharp reduction in new cases and no new reports in children. Continued vigilance is recommended: screening for renal impairment, use of more stable gadolinium chelates, consideration of non-contrast-enhanced MRI or alternative imaging modalities where appropriate. PMID:24146299

  6. Chemical zonation in garnet: kinetics or chemical equilibrium?

    NASA Astrophysics Data System (ADS)

    Ague, Jay; Chu, Xu; Axler, Jennifer

    2015-04-01

    Chemical zonation in garnet is widely used to reconstruct the pressure (P), temperature (T), time (t), and fluid (f) histories of mountain belts. Zonation is thought to result largely from changing P - T - t - f conditions during growth as well as post-growth intracrystalline diffusion. Chemical zonation is conventionally interpreted to mean that at least some of the garnet interior was out of chemical equilibrium with the matrix during metamorphism. In this case, thermally-activated diffusion in garnet is too slow to equalize chemical potentials. However, in their groundbreaking paper, Tajčmanová et al. (2014) postulate that in high-grade rocks, chemical zonation may actually reflect attainment of equilibrium. In this scenario, diffusion is fast but viscous relaxation is slow such that the zonation patterns directly mirror internal pressure gradients within garnet. Such zoning would likely be very different than typical concentric growth zonation. Furthermore, Baumgartner et al. (2010) hypothesize that given significant variations in the molar volumes of garnet endmembers, diffusional relaxation may produce internal pressure gradients if the garnet behaves as a near constant-volume system. Consequently, growth zoning could be preserved by pressure variations within the garnet that equalize chemical potentials and slow or stop diffusion (i.e., the garnet is chemically heterogeneous but maintains internal chemical equilibrium due to the pressure variations). This mechanism predicts that areas of garnet with small compositional contrasts would undergo more diffusional relaxation than areas with large contrasts. Moreover, generation of large internal pressure gradients approaching 1 GPa would be expected to induce deformation (e.g., fracturing) in regions of large compositional gradients. Strongly growth-zoned amphibolite facies garnet from the Barrovian zones, Scotland (Ague and Baxter, 2007) shows neither of these features. The sharp compositional gradients are instead interpreted to reflect short residence times at peak-T conditions. Existing diffusion coefficient calibrations predict shockingly short peak-T residence times

  7. Facile synthesis of gallium oxide hydroxide by ultrasonic irradiation of molten gallium in water.

    PubMed

    Kumar, Vijay Bhooshan; Gedanken, Aharon; Porat, Ze'ev

    2015-09-01

    This work describes the single-step synthesis of GaO(OH) by ultrasonic irradiation of molten gallium in warm water. The ultrasonic energy causes dispersion of the liquid gallium into micrometric spheres, as-well-as decomposition of some of the water into H and OH radicals. The OH radicals and the dissolved oxygen react on the surface of the gallium spheres to form crystallites of GaO(OH). These crystallites prevent the re-coalescence of the gallium spheres, and as the reaction proceeds all the gallium is converted into crystalline GaO(OH). PMID:25819681

  8. NIM Realization of the Gallium Triple Point

    Microsoft Academic Search

    Yan Xiaoke; Qiu Ping; Duan Yuning; Qu Yongmei

    2003-01-01

    In the last three years (1999 to 2001), the gallium triple-point cell has been successfully developed, and much corresponding research has been carried out at the National Institute of Metrology (NIM), Beijing, China. This paper presents the cell design, apparatus and procedure for realizing the gallium triple point, and presents studies on the different freezing methods. The reproducibility is 0.03

  9. Decreased gallium uptake in acute hematogenous osteomyelitis

    SciTech Connect

    Ang, J.G.; Gelfand, M.J.

    1983-07-01

    Decreased radiopharmaceutical uptake was noted on both bone and gallium scans in the case of acute hematogenous osteomyelitis of the right ilium (acetabular roof). This combination of findings is probably rare. The mechanism of decreased gallium uptake is unknown, but may be related to decreased blood flow.

  10. Extraction-chromatographic affinage in gadolinium-153 preparation production technology

    SciTech Connect

    Melnik, M.I.; Karelin, E.A.; Kuznetsov, R.A. [and others

    1993-12-31

    The gadolinium 153 preparation is used for production of medical gamma-sources which are applicable in bone densimeters for early diagnostics of osteoporosis. This preparation must meet strict requirements with respect to the content of europium radionuclides and specific activity. In The Research Institute of Atomic Reactors (RIAR) the gadolinium 153 is produced by neutron irradiation of Europium 151. This process is described.

  11. Application of Garnet-Accessory Phase Thermometry: a Combined EMP and SIMS Study

    Microsoft Academic Search

    J. M. Pyle; C. G. Daniel; F. S. Spear; G. D. Layne

    2003-01-01

    Fe-Mg exchange thermometry involving garnet and other phases requires appropriate bulk compositions, and is often compromised by bulk diffusion within garnet and retrograde net-transfer reactions that dissolve garnet or shift biotite compositions. Application of garnet-accessory phase thermometry provides a robust, multi-faceted alternative. Garnet-accessory phase pairs are resistant to diffusive reequilibration of Y and HREE, display evidence for an approach to

  12. Gallium Electromagnetic (GEM) Thrustor Concept and Design

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Markusic, Thomas E.

    2006-01-01

    We describe the design of a new type of two-stage pulsed electromagnetic accelerator, the gallium electromagnetic (GEM) thruster. A schematic illustration of the GEM thruster concept is given in Fig. 1. In this concept, liquid gallium propellant is pumped into the first stage through a porous metal electrode using an electromagneticpump[l]. At a designated time, a pulsed discharge (approx.10-50 J) is initiated in the first stage, ablating the liquid gallium from the porous electrode surface and ejecting a dense thermal gallium plasma into the second state. The presence of the gallium plasma in the second stage serves to trigger the high-energy (approx.500 I), send-stage puke which provides the primary electromagnetic (j x B) acceleration.

  13. Thermochromism in yttrium iron garnet compounds.

    PubMed

    Serier-Brault, Hélène; Thibault, Lucile; Legrain, Magalie; Deniard, Philippe; Rocquefelte, Xavier; Leone, Philippe; Perillon, Jean-Luc; Le Bris, Stéphanie; Waku, Jean; Jobic, Stéphane

    2014-12-01

    Polycrystalline yttrium iron garnet (Y3Fe5O12, hereafter labeled YIG) has been synthesized by solid-state reaction, characterized by X-ray diffraction, Mössbauer spectroscopy, and UV-vis-NIR diffuse reflectance spectroscopy, and its optical properties from room temperature (RT) to 300 °C are discussed. Namely, its greenish color at RT is assigned to an O(2-) ? Fe(3+) ligand-to-metal charge transfer at 2.57 eV coupled with d-d transitions peaking at 1.35 and 2.04 eV. When the temperature is raised, YIG displays a marked thermochromic effect; i.e., the color changes continuously from greenish to brownish, which offers opportunities for potential application as a temperature indicator for everyday uses. The origin of the observed thermochromism is assigned to a gradual red shift of the ligand-to-metal charge transfer with temperature while the positioning in energy of the d-d transitions is almost unaltered. Attempts to achieve more saturated colors via doping (e.g., Al(3+), Ga(3+), Mn(3+), ...) remained unsuccessful except for chromium. Indeed, Y3Fe5O12:Cr samples exhibit at RT the same color than the undoped garnet at 200 °C. The introduction of Cr(3+) ions strongly impacts the color of the Y3Fe5O12 parent either by an inductive effect or, more probably, by a direct effect on the electronic structure of the undoped material with formation of a midgap state. PMID:25382733

  14. Substitution of gadolinium ethylenediaminetetraacetate with phosphites: towards gadolinium deposit in nephrogenic systemic fibrosis.

    PubMed

    Gao, Song; Chen, Mao-Long; Zhou, Zhao-Hui

    2014-01-14

    In neutral media, reactions of gadolinium ethylenediaminetetraacetates with phosphorous acid result in the formation of the mixed-ligand polymeric complex K3n[Gd(EDTA)(HPO3)]n·7nH2O () and dimeric complex Na6[Gd2(EDTA)2(HPO3)2]·2.5NaCl·21H2O () (H4EDTA = ethylenediaminetetraacetic acid) in warm solution. Further substitution with citric acid gives the monomeric gadolinium citrate with EDTA (NH4)2Na[Gd(EDTA)(H2cit)]·4H2O (). The compounds were characterized by elemental analysis, single crystal X-ray diffraction, FT-IR, ESI-MS and thermogravimetric analysis. Structural analysis indicates that three coordinated water molecules in the gadolinium ethylenediaminetetraacetate trihydrates are replaced by phosphite ions (HPO3(2-)) in the compounds and . Gadolinium atoms are octa-coordinated by EDTA and the phosphite ion, the latter links adjacent Gd-EDTA units to generate an infinite one-dimensional chain in compound and a dimeric octatomic ring in . In complex , coordinated water molecules were substituted by the ?-hydroxy, ?-carboxy and ?-carboxy groups of citrate. Citrate is favourable for inhibiting the formation of Gd-EDTA phosphite. All the complexes are very easily soluble in water. The solution behavior of the isostructural lanthanum complexes was probed with (13)C and (31)P NMR spectra in D2O for comparison. ESI-MS analysis and recrystallization proved that complexes and dissociate to the monomeric unit of Gd-EDTA and free HPO3(2-) in aqueous solution. Substitutions of gadolinium ethylenediaminetetraacetates to and are attributed to be the cause of nephrogenic systemic fibrosis in some way. PMID:24132302

  15. Symplectites in garnet megacrysts captured by alkali mafic magma

    NASA Astrophysics Data System (ADS)

    Aseeva, Anna; Vysotskiy, Sergey; Karabtsov, Alexander; Alexandrov, Igor; Chashchin, Alexander

    2014-05-01

    Megacrysts are widespread in Cenozoic alkali-basalts of many volcanic provinces of the world. Garnet megacrysts containing symplectites are the most interesting, as can be used for reconstruction of physical and chemical conditions in liquid basalt at the moment of garnet crystal capture. The collection of garnet megacrysts and garnet-pyroxene aggregates from Shavaryn-Tsaram (Hangaj plateau, Mongolia) and Bartoj (Dzhida basaltic field, Russia) paleovolcanoes has studied. Cenozoic alkali basaltic volcanism of these two spatially separated areas is considered to be related to a uniform process of lithosphere spreading in Baikal and related Central Asian rift systems. The studying of garnet-pyroxene aggregate and fragments of garnet megacrysts from these two paleovolcanoes revealed two mineral associations: primary and secondary. The former includes garnet and clinopyroxene, the letter (symplectite) is presented by products of garnet disintegration (clinopyroxene remain unaltered). At least two paragenesis can be allocated: 1) shpinel - plagioclase-olivine sometimes with gedrite and orthopyroxene; 2) olivine (with glass). Experimental modeling of decomposition process in garnet megacryst has been carried out with the help of 'Selector' softwear at various P-T parameters. Physical and chemical conditions of this paragenesis occurrence have also been estimated by up-to-date geothermometers and geobarometers (T 950-1000 C, P 4-4.5 kbar. Conclusions: 1. Garnet megacrysts are apparently in non-equilibrium with alkali-basalts. They were formed in conditions corresponding to zones of mantle plums at the bottom of crust, in magmatic chambers at constant infiltration of fluid. Subsequently megacrysts were captured by alkali-basalt magma and taken out to the surface. 2. Kelyphitic rims on garnet megacrysts is a result of partial melting of megacrysts on interaction with the hosting alkali basaltic rock. During melting garnet transforms with the formation of Na-K glass and Mg olivine. Presence of alkaline volcanic glass in the kelyphitic rim testifies that Na and K migrate from alkali-basalt melt. 3. Subisothermal decompression inside garnet crystal yields solid-phase decomposition to form symplectite. Paragenesis of the formed minerals depends on garnet composition, P-T conditions and water presence/absence: 1) at pressure over 10 kbar and temperature more than 1300 C, garnet steadily co-exists with clinopyroxene; 2) at pressure and temperatures decreasing (4-8 kbar, 900-1300 C),garnet decomposes as follows: Sp+Pl+Ol sometimes with Opx, in the presence of water - Sp+Pl+Ol with Opx and Amph; 3) at temperature 950-1000 C and pressure 4-4.5 kbar, the following association is formed Sp+Opx+Pl; 4) if temperatures makes up 700-800 C, at the same pressure P=4 kbar, Sp+Opx+Cpx paragenesis is formed.

  16. Garnet polycrystals and the significance of clustered crystallization

    NASA Astrophysics Data System (ADS)

    Whitney, Donna L.; Seaton, Nicholas C. A.

    2010-10-01

    Polycrystalline garnets are common in metamorphic rocks and may form as a result of close spacing of nuclei (if clustering is early) or impingement of larger grains (if clustering occurs later in the growth history). The timing of clustering relative to garnet growth is relevant to understanding the formation and evolution of porphyroblasts and evaluating the significance (if any) of clustering. Electron backscattered diffraction (EBSD) analysis of garnet-bearing metamorphic rocks reveals the presence of polycrystalline garnet in nine localities examined in this study: the northern Appalachians (Vermont, Maine, New York, USA); North American Cordillera (North Cascades Range, Washington; Snake Range, Nevada, USA); western Rocky Mountains (British Columbia, Canada); southern Menderes Massif (Turkey); Santander Massif (Colombia); and the Sanandaj-Sirjan zone (Hamadan, Iran). In some samples, polycrystals comprise ~20-30% of garnets analyzed, and chemical and textural evidence suggests that early coalescence of garnet polycrystals is common. Some early-coalescing polycrystals exhibit growth zoning that is concentric about the geometric center of the polycrystal. In thin section, these garnets may be undetectable as polycrystals based on morphology or zoning. In some polycrystals, zoning is unrelated to the location of internal grain boundaries; in others, Fe-Mn-Mg zoning has a different pattern than that of Ca; zoning patterns may vary on the scale of a single thin section. In addition, some polycrystals are characterized by high-angle misorientation boundaries that may be in special (non-random) orientations, an observation that indicates that these polycrystals are not random clusters of grains. The presence of internal grain boundaries may affect diffusion pathways and length scales, and may facilitate communication of porphyroblast interiors with matrix phases, thereby influencing reaction history of the rock and the composition/zoning of garnet.

  17. Probing cytotoxicity of gadolinium hydroxide nanostructures.

    PubMed

    Hemmer, Eva; Kohl, Yvonne; Colquhoun, Victoria; Thielecke, Hagen; Soga, Kohei; Mathur, Sanjay

    2010-04-01

    Gadolinium hydroxide, Gd(OH)(3), nanostructures were examined for their possible use in imaging and tracking of cells and tissues by investigating their cellular interactions and cytotoxic behaviors. For this purpose, Gd(OH)(3) nanorods (length, several hundred nanometers; diameter, approximately 40 nm) and spherical nanoparticles (average diameter, <10 nm) were synthesized by solvothermal decomposition of gadolinium containing molecular precursors. After comprehensive characterization of material properties, human colon adenocarcinoma (Caco2) and human lung epithelial (A549) cells were incubated with Gd(OH)(3) nanostructures in concentrations up to 900 microg/mL to perform cytotoxicity assays (BrdU (5-bromo-2'-deoxyuridine), WST-1 (4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzol-disulfonate)) and living/dead staining. As observed in all in vitro assays, the investigated Gd(OH)(3) nanostructures do not induce any significant cytotoxic effect, making them promising candidates for a new class of contrast agents, which may overcome the limitations of organic stains such as photobleaching and single usage. PMID:20218658

  18. Clearance of liposomal gadolinium: in vivo decomplexation.

    PubMed

    Unger, E C; Fritz, T A; Tilcock, C; New, T E

    1991-01-01

    The contrast agents gadolinium-DTPA (diethylenetriaminepentaacetic acid), Gd-DOTA (tetraazacyclododecanetetraacetic acid), and Gd-HP-DO3A (1,4,7-tris[carboxymethyl]-10-[2' hydroxypropyl]-1,4,7,10-tetraazacyclododecane) are used in humans as extracellular contrast agents. Although free Gd+ ion is toxic, the intact Gd3+ complexes are rapidly excreted and are relatively nontoxic. Decomplexation with release of free gadolinium is a relevant clinical concern in patients with altered renal clearance. Blood pool contrast agents currently under development may have longer clearance half-lives and be more prone to decomplexation. The present study was designed to evaluate the clearance of liposomally encapsulated Gd3+ complexes (DTPA, DOTA, and HP-DO3A). The macrocyclic compounds had more rapid and complete clearance than DTPA (P less than .05). Parallel studies with carbon-14 and Gd-153-labeled complexes showed significant differences (P less than .05) in the amount of these isotopes retained in the heart, kidney, lungs, and spleen, providing strong supportive evidence for in vivo decomplexation. PMID:1823174

  19. Elimination of gadolinium-DTPA by peritoneal dialysis.

    PubMed

    Dörsam, J; Knopp, M V; Schad, L; Piesche, S; Carl, S; Oesingmann, N

    1995-01-01

    Magnetic resonance urography (MRU) after i.v. injection of gadolinium-DTPA (0.1 mmol/kg bodyweight) was performed in a patient with transplant dysfunction after renal allograft transplantation. Renal replacement therapy was accomplished by means of peritoneal dialysis. Gadolinium-DTPA concentrations in urine and dialysate were measured repeatedly during a 48-h period with inductively coupled plasma atomic emission spectrometry. The total 24-h creatinine clearance was 10.8 ml/min on day 1 and 13.7 ml/min on day 2. The corresponding total gadolinium clearance was 12.8 ml/min and 15.8 ml/min respectively. Gadolinium-DTPA was removed from the body through peritoneal dialysis at a mean clearance rate of 5.13 ml/min. Plasma half-life of gadolinium-DTPA was prolonged to 9 h. No side-effects due to gadolinium-DTPA were noted. MRU provided a better visualization of the morphology of the urinary tract than scintigraphic studies. By measuring the changes of signal intensity, the gadolinium excretion could be calculated. PMID:7478129

  20. Clinical Applications of Gallium-68

    PubMed Central

    Banerjee, Sangeeta Ray; Pomper, Martin G.

    2013-01-01

    Gallium-68 is a positron-emitting radioisotope that is produced from a 68Ge/68Ga generator. As such it is conveniently used, decoupling radiopharmacies from the need for a cyclotron on site. Gallium-68-labeled peptides have been recognized as a new class of radiopharmaceuticals showing fast target localization and blood clearance. 68Ga-DOTATOC, 8Ga-DOTATATE, 68Ga-DOTANOC, are the most prominent radiopharmaceuticals currently in use for imaging and differentiating lesions of various somatostatin receptor subtypes, overexpressed in many neuroendocrine tumors. There has been a tremendous increase in the number of clinical studies with 68Ga over the past few years around the world, including within the United States. An estimated ~10,000 scans are being performed yearly in Europe at about 100 centers utilizing 68Ga-labeled somatostatin analogs within clinical trials. Two academic sites within the US have also begun to undertake human studies. This review will focus on the clinical experience of selected, well-established and recently applied 68Ga-labeled imaging agents used in nuclear medicine. PMID:23522791

  1. Isoelectronic Traps in Gallium Phosphide

    NASA Astrophysics Data System (ADS)

    Christian, Theresa; Alberi, Kirstin; Beaton, Daniel; Fluegel, Brian; Mascarenhas, Angelo

    2015-03-01

    Isoelectronic substitutional dopants can result in strongly localized exciton traps within a host bandstructure such as gallium arsenide (GaAs) or gallium phosphide (GaP). These traps have received great attention for their role in the anomalous bandgap bowing of nitrogen or bismuth-doped GaAs, creating the dramatic bandgap tunability of these unusual dilute alloys. In the wider, indirect-bandgap host material GaP, these same isoelectronic dopants create bound states within the gap that can have very high radiative efficiency and a wealth of discrete spectral transitions illuminating the symmetry of the localized excitonic trap state. We will present a comparative study of nitrogen and bismuth isoelectronic traps in GaP. Research was supported by the U. S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division under contract DE-AC36-08GO28308 and by the Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF), made possible in part by the American Recovery and Reinvestment Act of 2009, administered by ORISE-ORAU under contract no. DE-AC05-06OR23100.

  2. Structure-Entropy Relationships in Aluminosilicate Garnets (Invited)

    NASA Astrophysics Data System (ADS)

    Geiger, C. A.; Dachs, E.

    2013-12-01

    Aluminosilicate garnet (X3Al2Si3O12) is a key rock-forming mineral whose geological occurrence is widespread. Various petrologic, geochemical and geophysical processes can be best interpreted if garnet's structure and thermodynamic properties are understood. Extensive research has been done on garnet's crystal-chemical properties using diffraction and spectroscopic measurements as well as computational methods. The level of understanding is, in general, good. In terms of macroscopic thermodynamic properties, there has also been much work done over the years. Here, however, the level of understanding is less. Consider the crystal chemistry and entropy behavior of two binary solid solutions, namely pyrope-grossular (Py-Gr) [(MgxCa1-x)3Al2Si3O12] and almandine-spessartine (Al-Sp) [(FexMn1-x)3Al2Si3O12]. The heat capacity, Cp, of a series of well characterized natural and synthetic almandine-spessartine garnets was recently measured between 3 and 300 K (Dachs et al., submitted). All garnets show a ?-type anomaly at low temperatures resulting from a paramagnetic-antiferromagnetic phase transition. The lattice heat capacity, Cp,vib, was calculated for each garnet member by applying the phonon dispersion model of Komada and Westrum (1997). This allows a decomposition of S298 into its vibrational (Svib) and magnetic (Smag) contributions. A full analysis shows that the Al-Sp binary is entropically ideal with ?Sex ? 0 at 298 K. Previously published calorimetric work on Py-Gr garnets shows, in contrast, substantial positive ?Sex across the join at 298 K (Dachs and Geiger, 2006). Why the difference? The vibrational behavior of the divalent X cations plays an important role in affecting macroscopic Cp,vib and Svib in aluminosilicate garnets. X-ray single-crystal diffraction and XAFS measurements show that the mean square amplitudes of vibration for Fe2+ in Al and Mn2+ in Sp are similar and, moreover, they do not vary significantly in magnitude as a function of composition across the Al-Sp binary. Vibrational modes in IR and Raman spectra of Al-Sp garnets show mostly continuous and linear variation in wavenumber across the binary. These results are fully consistent with the calorimetric work indicating ?Sex ? 0 at 298 K. In contrast, the mean square amplitudes of vibration of Mg and Ca in Py-Gr garnets are substantially different from each other. The behavior of IR and Raman modes in spectra of Py-Gr garnets are also quite different than the spectra of Al-Sp garnets. Low energy modes related to Ca and especially Mg do not shift linearly in energy across the Py-Gr join but soften in intermediate compositions. This behavior is considered to be the cause of the large positive ?Sex behavior. Al-Sp garnets differ, of course, from Py-Gr garnets because of their magnetic and electronic contributions to Cp and S.

  3. Removal of gadolinium nitrate from heavy water

    SciTech Connect

    Wilde, E.W.

    2000-03-22

    Work was conducted to develop a cost-effective process to purify 181 55-gallon drums containing spent heavy water moderator (D2O) contaminated with high concentrations of gadolinium nitrate, a chemical used as a neutron poison during former nuclear reactor operations at the Savannah River Site (SRS). These drums also contain low level radioactive contamination, including tritium, which complicates treatment options. Presently, the drums of degraded moderator are being stored on site. It was suggested that a process utilizing biological mechanisms could potentially lower the total cost of heavy water purification by allowing the use of smaller equipment with less product loss and a reduction in the quantity of secondary waste materials produced by the current baseline process (ion exchange).

  4. Motexafin gadolinium: a possible new radiosensitiser.

    PubMed

    Rodrigus, Patrick

    2003-07-01

    Motexafin gadolinium (MGd, PCI-0120, Xcytrin, a metallotexaphyrin developed by Pharmacyclics, is a redox active drug that selectively targets tumour cells with a potential action as a radiosensitiser. In vitro and in vivo models showed radiation enhancement when radiation followed MGd administration. Phase I and II clinical studies showed that MGd was well-tolerated with a maximum-tolerated dose set at 6.3 mg/kg. Acute side effects of discolouration of the sclera, skin and urine are reversible. The clinical efficacy was determined in an international Phase III trial for brain metastases with a significant difference in time to neurological progression for lung cancer brain metastases in favour of MGd and whole brain radiation versus whole brain radiation only. For the treatment of glioblastoma multiforme, promising results are found in a Phase I trial with a median survival of 17.3 months. Further investigation of the combination of MGd and radiotherapy will be worthwhile. PMID:12831354

  5. Modulated optical sensitivity with nanostructured gallium nitride

    NASA Astrophysics Data System (ADS)

    Wilkins, S. J.; Slomski, M. J.; Paskova, T.; Weyher, J. L.; Ivanisevic, A.

    2015-04-01

    Surface functionalization via etching of high aspect ratio gallium nitride (GaN) nanostructures provides a way to modulate the optical properties in addition to properties gained from unique topographical formations. In this study, planar layered (heteroepitaxy) and bulk free-standing gallium nitride were modified via a phosphonic acid (1H,1H,2H,2H-perfluorooctanephosphonic acid) assisted phosphoric acid etch in conjunction with an aqueous KOH + K2S2O8 formed gallium nitride nanostructured surface. Despite the high defect concentrations in the thin planar and nanostructured GaN layer, the nanostructured GaN sample produced improved photoluminescence intensities versus the high quality bulk free-standing gallium nitride. Subsequent treatments with additive and additive-free phosphoric etches provided a means of additional optical manipulation in the form of red-shifting the near-band-edge (NBE) emission of the nanostructured GaN sample and increasing the maximum NBE photoluminescence intensity.

  6. The thermal conductivity of liquid gallium

    Microsoft Academic Search

    M. J. Duggin

    1969-01-01

    Thermal conductivity measurements have been made on gallium over the range 360°K-590°K. Values of the Lorenz number are obtained for several temperatures and indicate that inelastic scattering occurs.

  7. Thermoelectric properties of alloys based on gadolinium selenides

    Microsoft Academic Search

    Yu. M. Goryachev; V. A. Obolonchik; T. M. Mikhlina; T. M. Yarmola

    1982-01-01

    The gadolinium selenide GdSe1.3 and its alloys are strongly degenerate semimetals of the n-type. These systems can provide a basis for the development of potentially useful thermoelectric materials. Electrotransport in the alloys investigated is effected by electrons in at least two subzones, a strongly degenerate and a weekly degenerate one. Substitution of tantalum and rhenium for gadolinium changes both the

  8. Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie T.; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

  9. Au-free Ohmic Contacts to Gallium Nitride and Graphene 

    E-print Network

    Ravikirthi, Pradhyumna

    2014-08-10

    This work deals with Au-free contact metallization schemes for gallium nitride (GaN) and graphene semiconductors. Graphene and gallium nitride are promising materials that can potentially be integrated together in the near future for high frequency...

  10. Window structure for passivating solar cells based on gallium arsenide

    NASA Technical Reports Server (NTRS)

    Barnett, Allen M. (Inventor)

    1985-01-01

    Passivated gallium arsenide solar photovoltaic cells with high resistance to moisture and oxygen are provided by means of a gallium arsenide phosphide window graded through its thickness from arsenic rich to phosphorus rich.

  11. Optical microcharacterization of gallium nitride and indium gallium nitride alloys

    NASA Astrophysics Data System (ADS)

    Srinivasan, Sridhar

    Gallium Nitride (GaN) and its alloys are attractive candidate materials for light-emitting applications in the visible and ultraviolet regions of the electromagnetic spectrum. The wide direct bandgap of the III-nitrides makes them very efficient light-emitters and their short bond length makes them extremely robust and durable. During the last decade, there have been rapid strides in the development of these materials and several devices based on them have already been commercialized. However, there are many issues with these materials that remain to be solved. This dissertation focuses on two main issues: one, the properties of Indium Gallium Nitride (InGaN) and two, the effect of dislocations on material properties. InGaN alloys are very difficult to grow, and a principal effort in the research community today is to achieve growth of high-quality films with high indium compositions. In order to overcome the problems associated with the growth of InGaN, it is important to gain an understanding of the basic nature of the material. In this work, the microstructure and electronic properties of thick InGaN epilayers has been studied. This enables investigation of material properties free of quantum confinement effects. The electronic properties of InGaN were observed to strongly vary with indium composition. Dislocations in the underlying GaN layer act as nucleation sites for phase separation and have a significant effect on material properties. The dislocation density was also found to play an important role in determining the strain relaxation mechanism in InGaN epilayers. The effect of dislocations on materials properties is an interesting problem that is being studied in great detail. In this study, it was found that the electronic properties in epitaxial lateral overgrowth of GaN are strongly dependent on the growth direction and unrelated to dislocation density. The properties appeared to be determined by point defects whose incorporation depends on the growth surface. Luminescence characteristics were studied across threading dislocations in semi-insulating GaN and were found to be closely related to the electrostatic potential measured by electron holography. This work has investigated important materials issues in GaN and InGaN and has contributed in developing a basic understanding of these materials.

  12. A novel technique for microstructure characterization of garnet films

    NASA Astrophysics Data System (ADS)

    Wo, P. C.; Munroe, P. R.; Vasiliev, M.; Xie, Z. H.; Alameh, K.; Kotov, V.

    2009-12-01

    Bismuth-substituted iron garnet exhibits remarkable magneto-optical properties in magnetic photonic crystal (MPC) structures, and has the potential to improve performance in optical integrated circuits for communication networks and optical sensing applications. The microstructure and thickness of these garnet films has a strong influence over their optical, magnetic and magneto-optic (MO) properties. The thickness of these films has been measured indirectly via optical interference and ellipsometry, which are unable to map thickness variations due to surface roughness of both the film and the substrate. However, little direct observation has been carried out to provide detailed information about the microstructure of the garnet films, especially in cross-section. All these have resulted in a lack of understanding of processing-microstructure-MO property relationship, which in turn impedes the development of high-performance garnet films. The combined use of focused ion beam (FIB) milling and transmission electron microscopy (TEM), described as the FIB-TEM method hereafter, provides a reliable, direct means of characterization of site-specific micron-sized regions of a specimen within a reasonable length of time. A sound understanding of processing-microstructure-MO property relationship enabled by FIB-TEM method is crucial in the design of the manufacturing processes for such functional films as well as nanostructures that have garnet layers. This paper reports the experimental procedures of FIB-TEM technique for characterization of these films and discusses the strength and issues associated with its application on (Bi, Dy) 3(Fe, Ga) 5O 12 garnet films.

  13. Garnet compositions and their use as indicators of peraluminous granitoid petrogenesis - southeastern Arabian Shield

    USGS Publications Warehouse

    du Bray, E.A.

    1988-01-01

    Garnet, an uncommon accessory mineral in igneous rocks, occurs in seven small peraluminous granitoid plutons in the southeastern Arabian Shield; textural equilibrium between garnet and other host granitoid minerals indicates that the garnets crystallized from their host magmas. Compositions of the garnets form three groups that reflect host-granitoid compositions, which in turn reflect source compositions and tectonic regimes in which the host magmas were generated. Garnets from the seven plutons have almandine-rich cores and spessartine-rich rims. This reverse zoning depicts host magma compositional evolution; i.e. rimward spessartine enrichment resulted from progressive, host-magma manganese enrichment. The garnets are heavy rare-earth element enriched; (Lu/La)N ranges from 13 to 355 and one of the garnets contains spectacularly elevated abundances of Y, Ta, Th, U, Zn, Zr, Hf, Sn, and Nb. Involvement of garnets with these trace element characteristics in magma genesis or evolution can have dramatic effects on trace element signatures of the resulting magmas. Other researchers suggest that Mn-enriched magmas are most conducive to garnet nucleation. Although the garnetiferous granitoids discussed here are slightly Mn enriched, other genetically similar peraluminous Arabian granitoids lack garnet; Mn enrichment alone does not guarantee garnet nucleation. The presence of excess alumina in the magma may be a prerequisite for garnet nucleation. ?? 1988 Springer-Verlag.

  14. Research paper Using garnet to constrain the duration and rate of water-releasing metamorphic

    E-print Network

    Baxter, Ethan F.

    method. Untreated "garnet" powders rich in mineral inclusions from each garnet zone were also analyzed. The powders fall off of the garnet-matrix isochron, likely indicating age inheritance in the inclusions, and heating of 100 °C, in less than 1.0 Myr. The short time interval represents a focused, rapid pulse

  15. The Origin of Garnet Megacrysts in Sulu UHP Clinopyroxenite, East China

    Microsoft Academic Search

    J. Liou; R. Zhang; T. Tsujimori; T. Li; S. Chen

    2003-01-01

    Abundant garnet megacrysts occur in one garnet clinopyroxenite layer from Rizhao of the Sulu UHP terrane, east China. The clinopyroxenite layers with various contents of garnet (trace to > 40%), ilmenite (< 5 %) and minor olivine form part of a strongly serpentinitzed peridotite body. Megacrystic Grt-bearing clinopyroxenite consists of variable amounts of megacrystic and porphyroblastic Grt, fine-grained matrix of

  16. Effect of Titanium on REE and HFSE Partitioning Between Garnet and Melt

    Microsoft Academic Search

    R. E. Dwarzski; D. S. Draper

    2004-01-01

    Garnet is a strong fractionator of trace elements and plays an important role in the petrogenetic history of planetary interiors at high pressure. In order to model petrogenetic processes that operate within terrestrial planets accurately, it is important to understand how garnet partitions rare earth and high field strength elements. Here we assess the influence of Ti on garnet-melt trace

  17. Anisotropy study of garnet films grown over substrates populated with gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Lang, G.; Bowen, D.; Hung, L.; Krafft, C.; Mayergoyz, I.

    2012-04-01

    Anisotropy of garnet films grown by liquid phase epitaxy (LPE) over (100)-oriented garnet substrates populated with gold nanoparticles is studied. The results of ferromagnetic resonance (FMR) and optical hysteresis loop measurements as well as optical images of domain structures of LPE-grown garnet films are presented and discussed.

  18. Speciation of scandium and gallium in soil.

    PubMed

    Po?edniok, Justyna

    2008-09-01

    A method for the speciation of scandium and gallium in soil has been developed. The sequential extraction scheme of Tessier et al. for heavy metals was examined for the scandium and gallium separation. The regents proposed by Tessier were used for the extraction, and only for the residual fraction the HClO4 was replaced with H2SO4. The optimum conditions for leaching scandium and gallium from the soil were chosen for each fraction. Very sensitive, spectrophotometric methods based on the mixed complexes of Sc(III) and Ga(III) with Chrome Azurol S and benzyldodecyldimethylammonium bromide were applied for the scandium and gallium determination after their separation by solvent extraction. 100% mesityl oxide and a 0.5M solution of 2-thenoyltrifluoroacetone in xylene were chosen for the extraction of scandium and butyl acetate was selected for gallium. Soil samples from two different regions of Poland were the object of this research. The content of scandium and gallium found in the individual fractions of Upper Silesia soil (industrial region) was [in microgg(-1)] Sc: I, 1.52; II, 0.53; III, 7.78; IV, 1.79; V, 0.20; Ga: I, 24.7; III, 29.2; IV, 35.4; V, 6.9. In Podlasie soil (agricultural region), the content of both elements was clearly lower. The total content of scandium and gallium in the five soil fractions was in good correlation with the total content of these elements in the soils found after HF-H2SO4 digestion. Analysis using the ICP-OES method gave comparable results. PMID:18653213

  19. Gadolinium-153 as a brachytherapy isotope

    NASA Astrophysics Data System (ADS)

    Enger, Shirin A.; Fisher, Darrell R.; Flynn, Ryan T.

    2013-02-01

    The purpose of this work was to present the fundamental dosimetric characteristics of a hypothetical 153Gd brachytherapy source using the AAPM TG-43U1 dose-calculation formalism. Gadolinium-153 is an intermediate-energy isotope that emits 40-100 keV photons with a half-life of 242 days. The rationale for considering 153Gd as a brachytherapy source is for its potential of patient specific shielding and to enable reduced personnel shielding requirements relative to 192Ir, and as an isotope for interstitial rotating shield brachytherapy (I-RSBT). A hypothetical 153Gd brachytherapy source with an active core of 0.84 mm diameter, 10 mm length and specific activity of 5.55 TBq of 153Gd per gram of Gd was simulated with Geant4. The encapsulation material was stainless steel with a thickness of 0.08 mm. The radial dose function, anisotropy function and photon spectrum in water were calculated for the 153Gd source. The simulated 153Gd source had an activity of 242 GBq and a dose rate in water 1 cm off axis of 13.12 Gy h-1, indicating that it would be suitable as a low-dose-rate or pulsed-dose-rate brachytherapy source. The beta particles emitted have low enough energies to be absorbed in the source encapsulation. Gadolinium-153 has an increasing radial dose function due to multiple scatter of low-energy photons. Scattered photon dose takes over with distance from the source and contributes to the majority of the absorbed dose. The anisotropy function of the 153Gd source decreases at low polar angles, as a result of the long active core. The source is less anisotropic at polar angles away from the longitudinal axes. The anisotropy function increases with increasing distance. The 153Gd source considered would be suitable as an intermediate-energy low-dose-rate or pulsed-dose-rate brachytherapy source. The source could provide a means for I-RSBT delivery and enable brachytherapy treatments with patient specific shielding and reduced personnel shielding requirements relative to 192Ir.

  20. Gadolinium-153 as a brachytherapy isotope.

    PubMed

    Enger, Shirin A; Fisher, Darrell R; Flynn, Ryan T

    2013-02-21

    The purpose of this work was to present the fundamental dosimetric characteristics of a hypothetical (153)Gd brachytherapy source using the AAPM TG-43U1 dose-calculation formalism. Gadolinium-153 is an intermediate-energy isotope that emits 40-100 keV photons with a half-life of 242 days. The rationale for considering (153)Gd as a brachytherapy source is for its potential of patient specific shielding and to enable reduced personnel shielding requirements relative to (192)Ir, and as an isotope for interstitial rotating shield brachytherapy (I-RSBT). A hypothetical (153)Gd brachytherapy source with an active core of 0.84 mm diameter, 10 mm length and specific activity of 5.55 TBq of (153)Gd per gram of Gd was simulated with Geant4. The encapsulation material was stainless steel with a thickness of 0.08 mm. The radial dose function, anisotropy function and photon spectrum in water were calculated for the (153)Gd source. The simulated (153)Gd source had an activity of 242 GBq and a dose rate in water 1 cm off axis of 13.12 Gy h(-1), indicating that it would be suitable as a low-dose-rate or pulsed-dose-rate brachytherapy source. The beta particles emitted have low enough energies to be absorbed in the source encapsulation. Gadolinium-153 has an increasing radial dose function due to multiple scatter of low-energy photons. Scattered photon dose takes over with distance from the source and contributes to the majority of the absorbed dose. The anisotropy function of the (153)Gd source decreases at low polar angles, as a result of the long active core. The source is less anisotropic at polar angles away from the longitudinal axes. The anisotropy function increases with increasing distance. The (153)Gd source considered would be suitable as an intermediate-energy low-dose-rate or pulsed-dose-rate brachytherapy source. The source could provide a means for I-RSBT delivery and enable brachytherapy treatments with patient specific shielding and reduced personnel shielding requirements relative to (192)Ir. PMID:23339848

  1. JOURNAL DE PHYSIQUE IV Colloque C4, supplkment au Journal de Physique 111,Volume4, avril1994

    E-print Network

    Boyer, Edmond

    spectrum at zero magnetic field at 2.2 K as a function of laser excitation wavelength. Fig. 2. Fluorescence+ fluorescence. associated with 2~ -, 4~~ transitions in gadolinium gallium garnet exhibits large broadening as compared with other ions with d3 shell. The laser excitation and fluorescence spectra without magnetic

  2. Coupled magnetostatic and electromagnetic oscillations in hexaferrite-dielectric heterostructures

    E-print Network

    Srinivasan, Gopalan

    substrates such as MgAl2O4, gadolinium gallium garnet, strontium gallate, or quartz. In ferrite­75 GHz in strontium hexaferrite-quartz structures is reported. Data on frequencies of the modes have been obtained as a function of the bias magnetic field and quantitatively analyzed for two cases: when ferrite

  3. The Role of the Gallium Scan in Primary Extranodal Lymphoma

    Microsoft Academic Search

    Raihan Hussain; David R. H. Christie; Val Gebski; Michael B. Barton; Simon M. Gruenewald

    The purpose of this study was to examine the factors influencing gallium scan positivity for patients with primary extranodal lym- phoma and to examine the role of the gallium scan in staging the disease and assessing response to initial treatment. Methods: Ninety-two patients with extranodal lymphoma who had a gallium scan were reviewed. The influences of tumor site, size, grade

  4. 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.

  5. Studies of narrow autoionizing resonances in gadolinium

    SciTech Connect

    Bushaw, Bruce A.; Nortershauser, W.; Blaum, K.; Wendt, Klaus

    2003-06-30

    The autoionization (AI) spectrum of gadolinium between the first and second limits has been investigated by triple-resonance excitation with high-resolution cw lasers. A large number of narrow AI resonances have been observed and assigned total angular momentum J values. The resonances are further divided into members of AI Rydberg series converging to the second limit or other ''interloping'' levels. Fine structure in the Rydberg series has been identified and interpreted in terms of Jc j coupling. A number of detailed studies have been performed on the interloping resonances: These include lifetime determination by lineshape analysis, isotope shifts, hyperfine structure, and photoionization saturation parameters. The electronic structure of the interloping levels is discussed in terms of these studies. Linewidths generally decrease with increasing total angular momentum and the J = 7 resonances are extremely narrow with Lorentzian widths ranging from < 1 MHz up to 157 MHz. The strongest resonances are found to have cross-sections of {approx}10-12 cm{sup 2} and photoionization can be saturated with powers available from cw diode lasers.

  6. Plasmon resonance enhancement of magneto-optic effects in garnets

    NASA Astrophysics Data System (ADS)

    Mayergoyz, I. D.; Lang, G.; Hung, L.; Tkachuk, S.; Krafft, C.; Rabin, O.

    2010-05-01

    Enhancement of magneto-optic effects by strong electric fields induced by plasmon resonances in metallic nanoparticles placed on (or embedded into) garnets is discussed. Theoretical and computational results on excitation of plasmon resonances in such particles are reported and compared to available experimental data.

  7. /sup 67/Gallium lung scans in progressive systemic sclerosis

    SciTech Connect

    Baron, M.; Feiglin, D.; Hyland, R.; Urowitz, M.B.; Shiff, B.

    1983-08-01

    /sup 67/Gallium lung scans were performed in 19 patients with progressive systemic sclerosis (scleroderma). Results were expressed quantitatively as the /sup 67/Gallium Uptake Index. The mean total pulmonary /sup 67/Gallium Uptake Index in patients was significantly higher than that in controls (41 versus 25), and 4 patients (21%) fell outside the normal range. There were no clinical or laboratory variables that correlated with the /sup 56/Gallium uptake. Increased pulmonary /sup 67/Gallium uptake in scleroderma may prove useful as an index of pulmonary disease activity.

  8. Garnet Porphyroblasts and the Tectonic Evolution of Iberia

    NASA Astrophysics Data System (ADS)

    Aerden, D. G.

    2013-12-01

    Porphyroblast inclusion trails constitute an exceptionally detailed record of deformation histories undergone by metamorphic rocks. Their orientations have been shown to be remarkably consistent in mountain belts and to relate to large-scale orogenic processes. For example, vertical and horizontal preferred orientations are almost universally developed and resulted from multiple gravitational collapse stages that periodically interrupted plate-driven (horizontal) crustal shortening. Over the past 20 years, a large body of orientation data has become available for Foliation Intersection Axes (FIA) defined by inclusion trails in orogenic belts around the world. This data reveals that FIAs in metamorphic regions generally can be grouped into a discrete number of age sets with distinctive geographic trends. Such FIA sequences apparently track shifts in the direction of crustal shortening with time. Garnet is a particularly useful porphyroblastic mineral where it comes to linking deformation and metamorphic paths, due to a unique combination of properties: (1) lengthy growth histories along extended P-T paths and in rocks with variable bulk compositions, (2) sub-spherical crystal shapes and rigid behavior favoring the nucleation of tectonic foliations against garnet edges and their preservation in continued garnet-growth stage, (3) chemical compositions sensitive to changes in metamorphic conditions that can be modeled thermodynamically, (4) abundance of datable micro-inclusions, such as monazite, and (5) the possibility of dating garnet itself via the Sm-Nd or Lu-Hf methods. In Iberia, integrated microstructural and petrological analysis of garnet porphyroblasts in the Betic Cordillera (European Alpine belt) has recently established a sequence of 4 FIA sets. The successive geographic trends of these FIA (NE-SW, NW-SE, ENE-WSW, and NNW-SSE) remarkably correlate with known changes in relative Iberia-Africa plate motion from ca. 50-10Ma. In Hercynian Iberia (Iberian Massif) inclusion trails in garnet and other porphyroblastic minerals maintain consistent NE-SW trends over hundreds of km distance, despite highly variable regional-scale fold trends. This data has allowed the recent discovery of the "Central Iberian Arc", an oroclinal structure whose origin and relationship with the Ibero-Armorican Arc are uniquely indicated by the studied garnet porphyroblasts.

  9. Complex chemical zoning in eclogite facies garnet reaction rims: the role of grain boundary diffusion

    NASA Astrophysics Data System (ADS)

    Prenzel, J.; Abart, R.; Keller, L.

    2009-03-01

    In metapelites of the Saualpe complex (Eastern Alps) continuous 10 µm to 20 µm wide garnet reaction rims formed along biotite-plagioclase and biotite-perthite interfaces. The pre-existing mineral assemblages are remnants of low pressure high temperature metamorphism of Permian age. The garnet reaction rims grew during the Cretaceous eclogite facies overprint. Reaction rim growth involved transfer of Fe and Mg components from the garnet-biotite interface to the garnet-feldspar interface and transfer of the Ca component in the opposite direction. The garnets show complex, asymmetrical chemical zoning, which reflects the relative contributions of short circuit diffusion along grain boundaries within the polycrystalline garnet reaction rims and volume diffusion through the grain interiors on bulk mass transfer. It is demonstrated by numerical modelling that the spacing of the grain boundaries, i.e. the grain size of the garnet in the reaction rim is a first order control on its internal chemical zoning.

  10. Interactions of gallium with zircaloy cladding 

    E-print Network

    Mitchell, Lee Josey

    1999-01-01

    likely explanation for this Ga loss is sputtering by the incident ion beam. The estimated concentrations of Ga and Zr based on the RBS results are listed in Table 2. Again, it appears that the gallium has diffused into interstitial positions within... of Ga with Zr at Oak Ridge National Laboratory [4] Based on RBS data of Figure 17, the calculated gallium fluence was 2. 3x10" Ga atoms/cm . Again, it appears that sputtering removed a significant amount of the surface material. 24 3000 2500? 2000...

  11. Radiation damage of gallium arsenide production cells

    NASA Technical Reports Server (NTRS)

    Mardesich, N.; Joslin, D.; Garlick, J.; Lillington, D.; Gillanders, M.; Cavicchi, B.; Scott-Monck, J.; Kachare, R.; Anspaugh, B.

    1987-01-01

    High efficiency liquid phase epitaxy (LPE) gallium arsenide cells were irradiated with 1 Mev electrons up to fluences of 1 times 10 to the 16th power cm-2. Measurements of spectral response and dark and illuminated I-V data were made at each fluence and then, using computer codes, the experimental data was fitted to gallium arsenide cell models. In this way it was possible to determine the extent of the damage, and hence damage coefficients in both the emitter and base of the cell.

  12. Method for Plutonium-Gallium Separation by Anodic Dissolution of a Solid Plutonium-Gallium Alloy

    SciTech Connect

    Miller, William E.; Tomczuk, Zygmunt

    1998-12-08

    Purified plutonium and gallium are efficiently recovered from a solid plutonium-gallium (Pu-Ga) alloy by using an electrorefining process. The solid Pu-Ga alloy is the cell anode, preferably placed in a moving basket within the electrolyte. As the surface of the Pu-Ga anode is depleted in plutonium by the electrotransport of the plutonium to a cathode, the temperature of the electrolyte is sufficient to liquify the surface, preferably at about 500 C, resulting in a liquid anode layer substantially comprised of gallium. The gallium drips from the liquified surface and is collected below the anode within the electrochemical cell. The transported plutonium is collected on the cathode surface and is recovered.

  13. Applying Lu-Hf garnet geochronology and inverse phase equilibria modeling to migmatites

    NASA Astrophysics Data System (ADS)

    Yakymchuk, C.; Brown, M.; Vervoort, J. D.

    2013-12-01

    Garnet-bearing assemblages are common in HT metamorphic rocks and are widely used to determine P-T conditions. Garnet is also a host for accessory minerals that may be used to determine the timing of garnet growth or breakdown. However, using accessory minerals to date garnet in HT metamorphic rocks may produce ambiguous or erroneous age results if these minerals were grown or modified subsequently due to fluid or melt infiltration along microfractures. Direct dating of garnet using the Sm-Nd and/or Lu-Hf isotope systems potentially avoids these problems. However, at temperatures above the solidus, the Sm-Nd isotope composition of garnet may become homogenized during post-peak cooling and evidence of prograde growth may be removed. The Lu-Hf isotope system in garnet is more robust and less susceptible to diffusion-controlled re-equilibration. Therefore, Lu-Hf dating of garnet has the potential to constrain the period of prograde garnet growth in HT metamorphic rocks. In the Fosdick migmatite-granite complex of West Antarctica, two episodes of HT garnet growth have been proposed based on U-Pb monazite ages from garnet-bearing migmatitic paragneisses and orthogneisses and U-Pb zircon ages from spatially associated peraluminous granites. Cores of monazite inclusions in garnet yield Carboniferous ages whereas the rims yield Cretaceous ages, and the garnet itself records Cretaceous Sm-Nd ages. The Sm-Nd ages were interpreted to represent diffusional resetting during the Cretaceous of garnet that grew in the Carboniferous. In this study, Lu-Hf garnet geochronology is used to test the hypothesis that garnet in the migmatitic paragneisses and orthogneisses is Carboniferous in age. We also assess the utility of the Lu-Hf system for dating garnet growth in rocks that have experienced superimposed HT metamorphic events. In addition, inverse phase equilibria modeling of open system melting is used to constrain the P-T conditions of garnet growth in migmatitic paragneisses and orthogneisses. In inverse modeling, melt is reintegrated into a residual bulk chemical composition in a stepwise fashion along a credible prograde P-T path to generate a plausible sub-solidus composition. This procedure generates a series of P-T pseudosections that may be used to constrain the P-T conditions of garnet growth. Garnet from across the Fosdick complex yields Lu-Hf ages of 115 to 111 Ma. The melt-reintegrated pseudosections show the onset of garnet growth at ~800°C between 0.6 and 1.0 GPa, with garnet growth continuing to the estimated peak P-T of 830-870°C at 0.6-0.75 GPa. Sm-Nd garnet ages of 102-99 Ma determined from a subset of the same samples overlap the range of U-Pb monazite ages (111 to 96 Ma) retrieved from these rocks. We interpret the monazite ages to date growth as trapped melt crystallized during cooling to the solidus whereas we interpret the Sm-Nd garnet ages to record diffusion-controlled re-equilibration during cooling. The results of this study demonstrate that: 1) Lu-Hf garnet geochronology can be used to successfully date garnet growth in deep crustal migmatites; and 2) garnet growth in the Fosdick complex occurred during the Cretaceous, which implies lower peak P-T conditions for the Carboniferous event than previously believed.

  14. Rheological contrast between garnet and clinopyroxene in the mantle wedge: An example from Higashi-akaishi peridotite mass, SW Japan

    Microsoft Academic Search

    Masashi Muramoto; Katsuyoshi Michibayashi; Jun-Ichi Ando; Hiroyuki Kagi

    2011-01-01

    Garnet clinopyroxenites occur within foliated dunite in the Higashi-akaishi peridotite mass, located within the subduction-type high-pressure\\/low-temperature Sanbagawa metamorphic belt. The garnet clinopyroxenites contain 3–80% garnet, and garnet and clinopyroxene are homogeneously distributed. Garnet crystals contain extensive, regular dislocation arrays and dislocation networks, suggesting that dislocation creep was the dominant deformation mechanism. Analyses of crystallographic orientation maps indicate similar grain sizes

  15. Four Terminal Gallium Nitride MOSFETs

    NASA Astrophysics Data System (ADS)

    Veety, Matthew Thomas

    All reported gallium nitride (GaN) transistors to date have been three-terminal devices with source, drain, and gate electrodes. In the case of GaN MOSFETs, this leaves the bulk of the device at a floating potential which can impact device threshold voltage. In more traditional silicon-based MOSFET fabrication a bulk contact can be made on the back side of the silicon wafer. For GaN grown on sapphire substrates, however, this is not possible and an alternate, front-side bulk contact must be investigated. GaN is a III-V, wide band gap semiconductor that as promising material parameters for use in high frequency and high power applications. Possible applications are in the 1 to 10 GHz frequency band and power inverters for next generation grid solid state transformers and inverters. GaN has seen significant academic and commercial research for use in Heterojunction Field Effect Transistors (HFETs). These devices however are depletion-mode, meaning the device is considered "on" at zero gate bias. A MOSFET structure allows for enhancement mode operation, which is normally off. This mode is preferrable in high power applications as the device has lower off-state power consumption and is easier to implement in circuits. Proper surface passivation of seminconductor surface interface states is an important processing step for any device. Preliminary research on surface treatments using GaN wet etches and depletion-mode GaN devices utilizing this process are discussed. Devices pretreated with potassium pursulfate prior to gate dielectric deposition show significant device improvements. This process can be applied to any current GaN FET. Enhancement-mode GaN MOSFETs were fabricated on magnesium doped p-type Wurtzite gallium nitride grown by Metal Organic Chemical Vapor Deposition (MOCVD) on c-plane sapphire substrates. Devices utilized ion implant source and drain which was activated under NH3 overpressure in MOCVD. Also, devices were fabricated with a SiO2 gate dielectric and metal gate. Preliminary devices exhibited high GaN-oxide interface state density, Dit, on the order of 1013 cm-2· eV-1. Additional experiments and device fabrication was focused on improving device performance through optimization of the ion implantation activation anneal as well as incorporation of a bulk p-type ohmic contact and migration to a thicker, lower defect density, HVPE-grown template substrate. The first reported MOSFET on HVPE grown GaN substrates (templates) is reported with peak measured drain current of 1.05 mA/mm and a normalized transconductance of 57 muS/mm. Fabricated devices exhibited large (greater than 1 muA) source-to-drain junction leakage which is attributed to low activated doping density in the MOCVD-grown p-type bulk. MOSFETs fabricated on template substrates show more than twice the measured drain current as similar devices fabricated on traditional MOCVD GaN on sapphire substrates for the same bias conditions. Also, template MOSFETs have decreased gate leakage which allowed for a much greater range of operation. This performance increase is attributed to a more than doubled effective channel mobility on template GaN MOSFETs due to decreased crystal defect scattering when compared to a MOCVD-grown GaN-on-sapphire MOSFET. Fabricated MOSFETs also exhibit decreased interface state density with lower bound of 2.2x1011 cm-2·eV-1 when compared to prelimary MOSFETs. This decrease is associated with the use of a sacrificial oxide cap during source/drain activation. Suggested work for continued research is also presented which includes experiments to improve source/drain ion implantation profile, utilization of selective area growth for the active area, improved n- and p-type ohmic contact resistance and investigation of alternate oxides.

  16. Spectroscopic Characterization and 3-MICROMETER CW Laser Operation of ERBIUM(3+):GADOLINIUM(3) GALLIUM(5) OXYGEN(12) and ERBIUM(3+):YTTRIUM(3) SCANDIUM(2) GALLIUM(3) OXYGEN(12)

    NASA Astrophysics Data System (ADS)

    Dinerman, Bradley Jay

    The spectroscopic and 3-?m laser properties of rm Er^{3+ }{:}Gd_3Ga_5O_{12 } and rm Er^{3+} {:}Y_3Sc_2Ga_3O_{12 } are investigated. The Judd-Ofelt Theory is applied to calculate radiative lifetimes, branching ratios, and radiative quantum efficiencies. The results reveal radiative lifetimes significantly longer than those actually observed for the ^4I_ {11/2}, ^4I_{9/2} , and ^4S_{3/2 } states, which indicate that strong quenching processes operate in these media. Radiative quantum efficiencies of 24% and 32% are observed from the ^4I _{11/2} state for GGG and YSGG, respectively. The role of upconversion is examined in an experiment in which the luminescence which occurs from the ^4S_{3/2} and ^4I_{9/1} states following chopped, cw pumping is analyzed in two time domains: that resulting from direct excitation and that resulting following upconversion-induced excitation. The ratio of upconversion-induced luminescence to pump-induced luminscence is quantified and applied to a simplified rate model, from which values of the ^4I_ {13/2} and ^4I _{11/2} upconversion coefficients, alpha_1 and alpha _2, are calculated. The calculated alpha_1 is typically larger than the calculated alpha_2, which partially explains the mechanism by which cw laser oscillation occurs. The 3-?m laser properties of Er:GGG and Er:YSGG are investigated using monolithic laser resonators. The lasers are pumped directly into the ^4I_{11/2} upper state near 0.97 ?m by either a Ti:sapphire or InGaAs diode laser. Greater than 0.5-W of 2.79-?m laser emission and nearly 0.3-W of 2.82-?m emission are observed from diode-pumped Er:YSGG and Er:GGG, respectively. The efficiencies and properties of the two host materials are typically very similar, yet YSGG categorically operates more efficiently than GGG. The spectral and spatial characteristics of the emission are also observed. The lasers typically operate on four or five longitudinal modes. Tunable, single-frequency emission is demonstrated from Er:YAG at 2.94-mu m. TEM_{00}-mode operation from GGG and YSGG is observed under Ti:sapphire -pumped conditions; multimode operation is observed from the diode-pumped system.

  17. Optical identification of the gallium vacancy in neutron-irradiated gallium arsenide

    Microsoft Academic Search

    Anouar Jorio; Aiguo Wang; Martin Parenteau; Cosmo Carlone; Nelson L. Rowell; Shyam M. Khanna

    1994-01-01

    Gallium arsenide grown by the metallorganic-chemical-vapor-deposition method was irradiated at room temperature with fast neutrons in the fluence range 1012 to 3×1015 cm-2 (1.00 MeV equivalent fluence in gallium arsenide). The effects of neutron irradiation were studied by photoluminescence (PL) spectroscopy in the energy range 0.5-1.55 eV. In the samples irradiated to 3×1013 cm-2 and higher fluences, we observe a

  18. Gadolinium-enhanced MRI in central nervous system Behçet's disease.

    PubMed

    Erdem, E; Carlier, R; Idir, A B; Masnou, P O; Moulonguet, A; Adams, D; Doyon, D

    1993-01-01

    Two cases of central nervous system Behçet's disease, studied by gadolinium-enhanced MRI, are presented. In one patient, whose clinical picture was dominated by a brain syndrome, the gadolinium enhancement resolved with clinical improvement, although the hyperintense areas in the mesencephalon on T2-weighted images persisted. In the second, who had a pseudobulbar palsy and a mild right hemiparesis, there were many abnormal areas, but an enhancing focus in the posterior limb of the left internal capsule was probably the lesion responsible for the hemiparesis. PMID:8433790

  19. Synchrotron X-Ray Fluorescence Microscopy of Gallium in Bladder Tissue following Gallium Maltolate Administration during Urinary Tract Infection

    PubMed Central

    Sampieri, Francesca; Chirino, Manuel; Hamilton, Don L.; Blyth, Robert I. R.; Sham, Tsun-Kong; Dowling, Patricia M.; Thompson, Julie

    2013-01-01

    A mouse model of cystitis caused by uropathogenic Escherichia coli was used to study the distribution of gallium in bladder tissue following oral administration of gallium maltolate during urinary tract infection. The median concentration of gallium in homogenized bladder tissue from infected mice was 1.93 ?g/g after daily administration of gallium maltolate for 5 days. Synchrotron X-ray fluorescence imaging and X-ray absorption spectroscopy of bladder sections confirmed that gallium arrived at the transitional epithelium, a potential site of uropathogenic E. coli infection. Gallium and iron were similarly but not identically distributed in the tissues, suggesting that at least some distribution mechanisms are not common between the two elements. The results of this study indicate that gallium maltolate may be a suitable candidate for further development as a novel antimicrobial therapy for urinary tract infections caused by uropathogenic E. coli. PMID:23877680

  20. Crystal-field theory and the S-state splitting of Fe3+ in yttrium gallium garnet

    Microsoft Academic Search

    Zhou Kang-Wei; Xie Jun-Kai; Ning You-Ming; Zhao Sang-Bo; Wu Ping-Feng

    1991-01-01

    Calculating the S-state splitting of a d5 ion (Fe3+, Mn2+) in a crystal has been a long-standing difficult problem since 1934 when it was discussed by Van Vleck and Penney. Low and Rosengarten have concluded that crystal-field theory is not capable of providing a unified interpretation for the spectrum and for the S-state zero-field splitting of d5 6S ions. In

  1. Measurement of pressure changes during laser-activated irrigant by an erbium, chromium: yttrium, scandium, gallium, garnet laser.

    PubMed

    Peeters, Harry Huiz; De Moor, Roeland J G

    2015-07-01

    The use of Er,Cr:YSGG laser to activate irrigants results in the creation of vapour bubbles and shockwaves. The present study evaluated the magnitude of pressure changes in the root canal during laser-activated irrigation. The root canal of a single extracted maxillary canine was enlarged to a size 40/0.06 file. A pressure sensor was inserted apically into the root canal. The tooth was processed as follows. In the EDTA condition, the tooth was irrigated with 17 % EDTA; in the NaOCl condition, the tooth was irrigated with 3 % NaOCl. In all conditions, the irrigants were activated at 0.75 and 1.75 W for 60 s using RFT2 and MZ2 tips; to analyse the effect of tip placement, the tip was activated at the orifice and after inserting the tip 5 mm deeper than the orifice. Data showed no significant difference between irrigation regimens (p?>?0.05). There were no significant differences of the pressure between RFT2 and MZ2 tips (p?>?0.05). The placement of tips closer to the apex resulted in significantly higher pressure than at the orifice (p?

  2. Gallium Electromagnetic (GEM) Thruster Performance Measurements

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Burton, Rodney L.; Polzin, K. A.

    2009-01-01

    Discharge current, terminal voltage, and mass bit measurements are performed on a coaxial gallium electromagnetic thruster at discharge currents in the range of 7-23 kA. It is found that the mass bit varies quadratically with the discharge current which yields a constant exhaust velocity of 20 km/s. Increasing the electrode radius ratio of the thruster from to 2.6 to 3.4 increases the thruster efficiency from 21% to 30%. When operating with a central gallium anode, macroparticles are ejected at all energy levels tested. A central gallium cathode ejects macroparticles when the current density exceeds 3.7 10(exp 8) A/square m . A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma. The spectra show that neutral, singly, and doubly ionized gallium species are present in the discharge, as well as annular electrode species at higher energy levels. Axial Langmuir triple probe measurements yield electron temperatures in the range of 0.8-3.8 eV and electron densities in the range of 8 x 10(exp )20 to 1.6 x 10(exp 21) m(exp -3) . Triple probe measurements suggest an exhaust plume with a divergence angle of 9 , and a completely doubly ionized plasma at the ablating thruster cathode.

  3. A Gallium Multiphase Equation of State

    NASA Astrophysics Data System (ADS)

    Crockett, Scott; Greeff, Carl

    2009-06-01

    A new SESAME multiphase gallium equation of state (EOS) has been developed. The equation of state includes two of the solid phases (Ga I, Ga III) and a fluid phase. The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We will also explore refreezing via isentropic release and compression.

  4. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, J.C.; Shul, R.J.

    1999-02-02

    An ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same are disclosed. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorus co-implantation, in selected III-V semiconductor materials. 19 figs.

  5. Thermodynamic binding constants for gallium transferrin

    SciTech Connect

    Harris, W.R.; Pecoraro, V.L.

    1983-01-18

    Gallium-67 is widely used as an imaging agent for tumors and inflammatory abscesses. It is well stablished that Ga/sup 3 +/ travels through the circulatory system bound to the serum iron transport protein transferrin and that this protein binding is an essential step in tumor localization. However, there have been conflicting reports on the magnitude of the gallium-transferrin binding constants. Therefore, thermodynamic binding constants for gallium complexation at the two specific metal binding sites of human serum transferrin at pH 7.4 and 5 mM NaHCO/sub 3/ have been determined by UV difference spectroscopy. The conditional constants calculated for 27 mM NaHCO/sub 3/ are log K/sub 1/* = 20.3 and log K/sub 2/* = 19.3. These results are discussed in relation to the thermodynamics of transferrin binding of Fe/sup 3 +/ and to previous reports on gallium binding. The strength of transferrin complexation is also compared to that of a series of low molecular weight ligands by using calculated pM values (pM = -log (Ga(H/sub 2/O)/sub 6/)) to express the effective binding strength at pH 7.4.

  6. A Gallium Multiphase Equation of State

    Microsoft Academic Search

    Scott D Crockett; Carl Greeff

    2009-01-01

    A new SESAME multiphase gallium equation of state (EOS) has been developed. The equation of state includes two of the solid phases (Ga I, Ga III) and a fluid phase. The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We will also explore refreezing via isentropic release and compression.

  7. A GALLIUM MULTIPHASE EQUATION OF STATE

    Microsoft Academic Search

    Scott D. Crockett; Carl W. Greeff

    2009-01-01

    A new SESAME multiphase Gallium equation of state (EOS) has been developed. It includes three of the solid phases (Ga I, Ga II, Ga III) and a fluid phase (liquid?gas). The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We also explore the possibility of re-freezing via dynamic means such as

  8. a Gallium Multiphase Equation of State

    Microsoft Academic Search

    Scott D. Crockett; Carl W. Greeff

    2009-01-01

    A new SESAME multiphase Gallium equation of state (EOS) has been developed. It includes three of the solid phases (Ga I, Ga II, Ga III) and a fluid phase (liquid\\/gas). The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We also explore the possibility of re-freezing via dynamic means such as

  9. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, John C. (Albuquerque, NM); Shul, Randy J. (Albuquerque, NM)

    1999-01-01

    An all-ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorous co-implantation, in selected III-V semiconductor materials.

  10. Chemistry and Pharmacokinetics of Gallium Maltolate, a Compound With High Oral Gallium Bioavailability

    PubMed Central

    Tanner, Trevor; Godfrey, Claire; Noll, Bruce

    2000-01-01

    Gallium maltolate, tris(3-hydroxy-2-methyl-4H-pyran-4-onato)gallium (GaM), is an orally active gallium compound for therapeutic use. It is moderately soluble in water (10.7 ± 0.9 mg/mL at 25?C) with an octanol partition coefficient of 0.41±0.08. The molecule is electrically neutral in aqueous solution at neutral pH; a dilute aqueous solution (2.5 ×10?-5 M) showed little dissociation at pH 5.5-8.0. Single crystal X-ray diffraction analysis found the GaM molecule to consist of three maltolate ligands bidentately bound to a central gallium atom in a propeller-like arrangement, with one of the ligands disordered in two possible orientations. The compound is orthorhombic, space group Pbca, unit cell a = 16.675(3), b = 12.034(2), c = 18.435(2) Å at 158K. GaM was administered to healthy human volunteers at single doses of 100, 200, 300, and 500 mg (three subjects per dose). GaM was very well tolerated. Oral absorption of Ga into plasma was fairly rapid (absorption half life = 0.8-2.0h), with a central compartment excretion half life of 17-21h. Absorption appeared dose proportional over the dosage range studied. Estimated oral gallium bioavailability was approximately 25-57%, based on comparison with published data on intravenous gallium nitrate. Urinary Ga excretion following oral GaM administration was approximately 2% of the administered dose over 72h, in contrast to 49-94% urinary Ga excretion over 24h following i.v. gallium nitrate administration. We suggest that oral administration of GaM results in nearly all plasma gallium being bound to transferrin, whereas i.v. administration of gallium nitrate results in formation of considerable plasma gallate [Ga(OH)4?], which is rapidly excreted in the urine. These data support the continued investigation of GaM as an orally active therapeutic gallium compound. PMID:18475921

  11. Gallium 67 scintigraphy in glomerular disease

    SciTech Connect

    Bakir, A.A.; Lopez-Majano, V.; Levy, P.S.; Rhee, H.L.; Dunea, G.

    1988-12-01

    To evaluate the diagnostic usefulness of gallium 67 scintigraphy in glomerular disease, 45 patients with various glomerulopathies, excluding lupus nephritis and renal vasculitis, were studied. Persistent renal visualization 48 hours after the gallium injection, a positive scintigram, was graded as + (less than), ++ (equal to), and +++ (greater than) the hepatic uptake. Positive scintigrams were seen in ten of 16 cases of focal segmental glomerulosclerosis, six of 11 cases of proliferative glomerulonephritis, and one case of minimal change, and one of two cases of membranous nephropathy; also in three of six cases of sickle glomerulopathy, two cases of diabetic neuropathy, one of two cases of amyloidosis, and one case of mild chronic allograft rejection. The 25 patients with positive scans were younger than the 20 with negative scans (31 +/- 12 v 42 +/- 17 years; P less than 0.01), and exhibited greater proteinuria (8.19 +/- 7.96 v 2.9 +/- 2.3 S/d; P less than 0.01) and lower serum creatinine values (2 +/- 2 v 4.1 +/- 2.8 mg/dL; P less than 0.01). The amount of proteinuria correlated directly with the intensity grade of the gallium image (P less than 0.02), but there was no correlation between the biopsy diagnosis and the outcome of the gallium scan. It was concluded that gallium scintigraphy is not useful in the differential diagnosis of the glomerular diseases under discussion. Younger patients with good renal function and heavy proteinuria are likely to have a positive renal scintigram regardless of the underlying glomerulopathy.

  12. Gallium nitride nanowire electromechanical resonators

    NASA Astrophysics Data System (ADS)

    Gray, Jason Michael

    Nanoscale mechanical resonators are of great interest for high-resolution sensing applications, where the small resonator mass and high quality factor (Q, defined as resonance frequency f0 over full width at half maximum power) lead to unprecedented sensitivity. Here, we investigate gallium nitride (GaN) nanowire (NW) resonators. The single-crystal, c-axis NWs are 5 mum -- 20 mum long, with diameters from 50 nm -- 500 nm, and grow essentially free of defects. Our initial experiments involve measuring the resonances of as-grown NWs in a scanning electron microscope, where we observe exceptionally high Q values of 10 4 -- 105, one to two orders of magnitude higher than most NWs of comparable size. Using a single NW as a mass sensor, we then demonstrate a sub-attogram mass sensitivity. To provide a more flexible measurement technique that avoids electron-microscope detection, we fabricate doubly clamped NWs with an entirely electronic drive and readout scheme using a combination of lithographic patterning and dielectrophoresis. An electrostatic gate induces vibration, while readout utilizes the piezoresistivity of GaN. Observed resonances range from 9--36 MHz with Q values typically around 103 at room temperature and 10 -4 Pa. We use the behavior of f0 and Q to sense the NW's local environment, such as the additional sources of energy dissipation not present in the as-grown NWs. By cooling the device to 8 K, Q increases by an order of magnitude to above 104, with a highest value to date of 26,000 under vacuum. We explore additional NW properties through the thermal noise in the NW's mechanical motion and the exponential decay of mechanical motion in the presence of burst drive. Finally, we investigate the low-frequency 1/f parameter noise displayed by f0. We show that the noise in f0 is consistent with noise in the NW's resistance leading to temperature noise from local Joule heating, which in turn generates resonance frequency noise. For sensor applications, there will be optimal drive conditions that balance the f 0 noise with the signal-to-noise ratio of the system. With these insights, along with the simple drive and readout technique, these GaN-NW doubly clamped resonators have significant potential for high-resolution sensing applications.

  13. Thermophysical Properties of Sulfides of Lanthanum, Praseodymium, Gadolinium, and Dysprosium

    Microsoft Academic Search

    G. G. Gadzhiev; Sh. M. Ismailov; M. M. Khamidov; Kh. Kh. Abdullaev; V. V. Sokolov

    2000-01-01

    The temperature dependence of the thermal conductivity, electrical conductivity, thermoelectromotive force, and thermal expansion coefficient for sulfides of lanthanum, gadolinium, praseodymium and dysprosium of the composition Ln3 – xVxS4 is investigated in the temperature range from 300 to 1200 K. It is shown that the transfer phenomena and thermoelectrical properties of the investigated compositions depend on the concentration of current

  14. 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 0?2? search), 136Ce (2?+ candidate with one of the highest Q2?). The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2? 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.

  15. Thermal degradation study of gadolinium and lutetium methanesulfonates

    Microsoft Academic Search

    Maria de F. V. de Moura; Jivaldo do R. Matos; Robson F. de Farias

    2004-01-01

    The synthesis, characterization and thermal degradation study of gadolinium and lutetium methanesulfonates is reported. The prepared salts were characterized by elemental analysis and infrared spectroscopy. The thermal degradation study was performed by using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). By using thermogravimetric data, a kinetic study of the dehydration of Gd and Lu methanesulfonates is

  16. Asymptomatic renal abscess: Evaluation with gadolinium DTPA-enhanced MRI

    Microsoft Academic Search

    K. M. Cyran; P. J. Kenney

    1994-01-01

    Incidental detection of renal mass in a transplant patient is a diagnostic challenge. These patients are at risk for the development of neoplasms and, more commonly, infection with atypical organisms. Symptomatology may be lacking in either, and both conditions may present with similar symptoms. Magnetic resonance imaging (MRI) evaluation with gadolinium DTPA is helpful in the evaluation of asymptomatic renal

  17. Timing and duration of garnet granulite metamorphism in magmatic arc crust, Fiordland, New Zealand

    USGS Publications Warehouse

    Stowell, H.; Tulloch, A.; Zuluaga, C.; Koenig, A.

    2010-01-01

    Pembroke Granulite from Fiordland, New Zealand provides a window into the mid- to lower crust of magmatic arcs. Garnet Sm-Nd and zircon U-Pb ages constrain the timing and duration of high-P partial melting that produced trondhjemitic high Sr/Y magma. Trace element zoning in large, euhedral garnet is compatible with little post growth modification and supports the interpretation that garnet Sm-Nd ages of 126.1??2.0 and 122.6??2.0. Ma date crystal growth. Integration of the garnet ages with U-Pb zircon ages elucidates a history of intrusion(?) and a protracted period of high-temperature metamorphism and partial melting. The oldest zircon ages of 163 to 150. Ma reflect inheritance or intrusion and a cluster of zircon ages ca. 134. Ma date orthopyroxene-bearing mineral assemblages that may be magmatic or metamorphic in origin. Zircon and garnet ages from unmelted gneiss and garnet reaction zones record garnet granulite facies metamorphism at 128 to 126. Ma. Peritectic garnet and additional zircon ages from trondhjemite veins and garnet reaction zones indicate that garnet growth and partial melting lasted until ca. 123. Ma. Two single fraction garnet ages and young zircon ages suggest continued high-temperature re-equilibration until ca. 95. Ma. Phase diagram sections constrain orthopyroxene assemblages to <0.6 GPa @ 650??C, peak garnet granulite facies metamorphic conditions to 680-815??C @ 1.1-1.4. GPa, and a P-T path with a P increase of???0.5. GPa. These sections are compatible with water contents???0.28wt.%, local dehydration during garnet granulite metamorphism, and <0.3. GPa P increases during garnet growth. Results demonstrate the utility of integrated U-Pb zircon and Sm-Nd garnet ages, and phase diagram sections for understanding the nature, duration, and conditions of deep crustal metamorphism and melting. Geochronologic and thermobarometric data for garnet granulite indicate that thickening of arc crust, which caused high-pressure metamorphism in northern Fiordland, must have occurred prior to 126. Ma, that loading occurred at a rate of ca. 0.06. GPa/m.y., and that garnet granulite metamorphism lasted 3-7m.y. Locally-derived partial melts formed and crystallized in considerably less than 10 and perhaps as little as 3m.y. ?? 2010 Elsevier B.V.

  18. Molecular field coefficients of terbium, dysprosium and holmium iron garnets

    Microsoft Academic Search

    M. Guillot; P. Feldmann; H. Le Gall; M. Fadly

    1978-01-01

    Molecular field coefficients related to the rare earth iron interactions are determined in rare earth iron garnets TbIG, DyIG, HoIG. An analysis of the temperature dependences of the single crystals magnetization and of the susceptibilities shows that these parameters are temperature dependent in 70-300K range. Discontinuities of nacand ndcoccuring at the compensation temperature are found. Nevertheless, the molecular field acting

  19. Sublattice Magnetic Relaxation in Rare Earth Iron Garnets

    SciTech Connect

    McCloy, John S.; Walsh, Brian

    2013-07-08

    The magnetic properties of rare earth garnets make them attractive materials for applications ranging from optical communications to magnetic refrigeration. The purpose of this research was to determine the AC magnetic properties of several rare earth garnets, in order to ascertain the contributions of various sublattices. Gd3Fe5O¬12, Gd3Ga5O12, Tb3Fe5O12, Tb3Ga5O12, and Y3Fe5O12 were synthesized by a solid state reaction of their oxides and verified by x-ray diffraction. Frequency-dependent AC susceptibility and DC magnetization were measured versus temperature (10 – 340 K). Field cooling had little effect on AC susceptibility, but large effect on DC magnetization, increasing magnetization at the lowest temperature and shifting the compensation point to lower temperatures. Data suggest that interaction of the two iron lattices results in the two frequency dependent magnetic relaxations in the iron garnets, which were fit using the Vogel-Fulcher and Arrhenius laws.

  20. A YIG\\/GGG\\/GaAs-Based Magnetically Tunable Wideband Microwave BandPass Filter Using Cascaded Band-Stop Filters

    Microsoft Academic Search

    Gang Qiu; Chen S. Tsai; Bert S. T. Wang; Yun Zhu

    2008-01-01

    A yttrium iron garnet\\/gadolinium gallium garnet-gallium arsenide (YIG\\/GGG-GaAs)-based magnetically-tunable wideband microwave band-pass filter with large tuning ranges for the center frequency (5.90-17.80 GHz) and the bandwidth (1.27-2.08 GHz) in the pass-band using a pair of cascaded band-stop filters is reported. The design and numerical simulation of the band-pass filter that incorporates multisegment microstrip meander-lines and 2-D nonuniform bias magnetic fields

  1. Contrasting behaviour of anthropogenic gadolinium and natural rare earth elements in estuaries and the gadolinium input into the North Sea

    Microsoft Academic Search

    Serkan Kulaksiz; Michael Bau

    2007-01-01

    All major rivers in northwestern Germany that flow into the North Sea, including the Weser River, display rare earth element (REE) patterns with large positive gadolinium (Gd) anomalies that indicate the presence of anthropogenic Gd derived from contrast agents used in magnetic resonance imaging. This microcontaminant cannot be removed by common sewage treatment technology and enters rivers and lakes with

  2. Oxygen isotope constraints on the origin of high-Cr garnets from kimberlites

    Microsoft Academic Search

    Zhengrong Wang; Claire Bucholz; Brian Skinner; Nobumichi Shimizu; John Eiler

    The association between diamonds and high-Cr, sub-calcic garnets from kimberlites suggests that garnets have experienced high pressure (and presumably, high temperature) conditions in the subcontinental lithosphere mantle (SCLM). The oxygen isotope compositions of these garnets are generally reported to be lower than average values of mantle olivines (~5.2‰)—opposite the sense of oxygen isotope fractionation expected at high-temperature equilibrium, and to

  3. Garnet pyroxenite and eclogite in the Bohemian Massif: geochemical evidence for Variscan recycling of subducted lithosphere

    Microsoft Academic Search

    L. G. Medaris; B. L. Beard; C. M. Johnson; J. W. Valley; M. J. Spicuzza; E. Jelínek; Z. Mísâr

    1995-01-01

    High-temperature, high-pressure eclogite and garnet pyroxenite occur as lenses in garnet peridotite bodies of the Gföhl nappe in the Bohemian Massif. The high-pressure assemblages formed in the mantle and are important for allowing investigations of mantle compositions and processes. Eclogite is distinguished from garnet pyroxenite on the basis of elemental composition, with mg number 2O > 0.75 wt.%, Cr2O3 Nd,

  4. Garnet pyroxenite and eclogite in the Bohemian Massif: geochemical evidence for Variscan recycling of subducted lithosphere

    Microsoft Academic Search

    L. G. Medaris; B. L. Beard; C. M. Johnson; J. W. Valley; M. J. Spicuzza; E. Jelínek; Z. Mísâr

    1995-01-01

    High-temperature, high-pressure eclogite and garnet pyroxenite occur as lenses in garnet peridotite bodies of the Gföhl nappe in the Bohemian Massif. The high-pressure assemblages formed in the mantle and are important for allowing investigations of mantle compositions and processes. Eclogite is distinguished from garnet pyroxenite on the basis of elemental composition, with mg number <80, Na2O > 0.75 wt.%, Cr2O3

  5. Garnet pyroxenite and eclogite in the Bohemian Massif: geochemical evidence for Variscan recycling of subducted lithosphere

    Microsoft Academic Search

    L. G. Medaris-Jr; B. L. Beard; C. M. Johnson; J. W. Valley; M. J. Spicuzza; E. Jelínek; Z. Mísar

    1995-01-01

    High-temperature, high-pressure eclogite and garnet pyroxenite occur as lenses in garnet peridotite bodies of the Gföhl nappe in the Bohemian Massif. The high-pressure assemblages formed in the mantle and are important for allowing investigations of mantle compositions and processes. Eclogite is distinguished from garnet pyroxenite on the basis of elemental composition, with mg number <80, Na2O>0.75 wt.%, Cr2O3<0.15 wt.% and

  6. Morphological evidence for diffusion-controlled growth of garnet from metapelites

    NASA Astrophysics Data System (ADS)

    Gulbin, Yu. L.; Glazov, A. I.

    2013-12-01

    The surface microtopography of garnet from metamorphic schists of the northern Ladoga region has been investigated. The morphology of garnet is distinguished by a rough stepped surface on dodecahedral faces {110} and by the absence of sharp crystal edges. As follows from experimental results on crystal growth under hydrothermal conditions, the microtopography pattern gives evidence for a highly oversaturated inter-granular medium and the important role of diffusion as a factor controlling garnet growth.

  7. Deposition of gold nanoparticles on liquid phase epitaxy grown garnet films and Faraday rotation enhancement

    NASA Astrophysics Data System (ADS)

    Lang, G. S.; Bowen, D.; Krafft, C.; Mayergoyz, I. D.

    2013-05-01

    Plasmon resonance induced Faraday rotation enhancement in liquid phase epitaxy grown garnet films with gold nanoparticles on their surfaces is discussed. Experimental results are presented, which reveal stronger Faraday rotation enhancement for gold nanoparticles obtained by the annealing of thicker gold films evaporated on garnet film surfaces. This stronger Faraday rotation enhancement can be attributed to larger dimensions and separations of gold nanoparticles, which increase the extent of penetration of plasmon resonance induced electric fields into garnet films.

  8. Interactions of zircaloy cladding with gallium -- 1997 status

    SciTech Connect

    Wilson, D.F.; DiStefano, J.R.; King, J.F.; Manneschmidt, E.T.; Strizak, J.P.

    1997-11-01

    A four phase program has been implemented to evaluate the effect of gallium in mixed oxide (MOX) fuel derived from weapons grade (WG) plutonium on Zircaloy cladding performance. The objective is to demonstrate that low levels of gallium will not compromise the performance of the MOX fuel system in LWR. This graded, four phase experimental program will evaluate the performance of prototypic Zircaloy cladding materials against: (1) liquid gallium (Phase 1), (2) various concentrations of Ga{sub 2}O{sub 3} (Phase 2), (3) centrally heated surrogate fuel pellets with expected levels of gallium (Phase 3), and (4) centrally heated prototypic MOX fuel pellets (Phase 4). This status report describes the results of an initial series of tests for phases 1 and 2. Three types of tests are being performed: (1) corrosion, (2) liquid metal embrittlement (LME), and (3) corrosion mechanical. These tests are designed to determine the corrosion mechanisms, thresholds for temperature and concentration of gallium that may delineate behavioral regimes, and changes in mechanical properties of Zircaloy. Initial results have generally been favorable for the use of WG-MOX fuel. The MOX fuel cladding, Zircaloy, does react with gallium to form intermetallic compounds at {ge} 300 C; however, this reaction is limited by the mass of gallium and is therefore not expected to be significant with a low level (in parts per million) of gallium in the MOX fuel. While continued migration of gallium into the initially formed intermetallic compound results in large stresses that can lead to distortion, this is also highly unlikely because of the low mass of gallium or gallium oxide present and expected clad temperatures below 400 C. Furthermore, no evidence for grain boundary penetration by gallium has been observed.

  9. Interactions of Zircaloy cladding with gallium: 1998 midyear status

    SciTech Connect

    Wilson, D.F.; DiStefano, J.R.; Strizak, J.P.; King, J.F.; Manneschmidt, E.T.

    1998-06-01

    A program has been implemented to evaluate the effect of gallium in mixed-oxide (MOX) fuel derived from weapons-grade (WG) plutonium on Zircaloy cladding performance. The objective is to demonstrate that low levels of gallium will not compromise the performance of the MOX fuel system in a light-water reactor. The graded, four-phase experimental program was designed to evaluate the performance of prototypic Zircaloy cladding materials against (1) liquid gallium (Phase 1), (2) various concentrations of Ga{sub 2}O{sub 3} (Phase 2), (3) centrally heated surrogate fuel pellets with expected levels of gallium (Phase 3), and (4) centrally heated prototypic MOX fuel pellets (Phase 4). This status report describes the results of a series of tests for Phases 1 and 2. Three types of tests are being performed: (1) corrosion, (2) liquid metal embrittlement, and (3) corrosion-mechanical. These tests will determine corrosion mechanisms, thresholds for temperature and concentration of gallium that may delineate behavioral regimes, and changes in the mechanical properties of Zircaloy. Initial results have generally been favorable for the use of WG-MOX fuel. The MOX fuel cladding, Zircaloy, does react with gallium to form intermetallic compounds at {ge}300 C; however, this reaction is limited by the mass of gallium and is therefore not expected to be significant with a low level (parts per million) of gallium in the MOX fuel. Although continued migration of gallium into the initially formed intermetallic compound can result in large stresses that may lead to distortion, this was shown to be extremely unlikely because of the low mass of gallium or gallium oxide present and expected clad temperatures below 400 C. Furthermore, no evidence for grain boundary penetration by gallium has been observed.

  10. The physics and modeling of gallium arsenide solar cells

    Microsoft Academic Search

    Paul David DeMoulin

    1988-01-01

    Gallium arsenide is a versatile semiconductor used in many devices. Due to its nearly ideal bandgap energy for solar energy conversion and its compatibility with AlGaAs, gallium arsenide's use in solar cells has been widespread and is growing. Only its chief rival, silicon, is more popular as a high-efficiency material. To continue gallium arsenide's growth, this research was conducted for

  11. Light Elements in the Core: Constraints from Gallium Partitioning

    NASA Astrophysics Data System (ADS)

    Blanchard, I.; Badro, J.; Siebert, J.; Ryerson, F. J.

    2014-12-01

    The formation of Earth's core has left a compositional imprint on the mantle, depleting and fractionating most of its siderophile (iron-loving) elements. Gallium is a moderately siderophile, hence it should be strongly depleted in the mantle. However, gallium concentration in the mantle matches that of lithophile (silicate-loving) elements having the same volatility. That is to say that either gallium behaves as a lithophile element during core formation, or a large influx of gallium was brought to the Earth after the core had formed. Geochemical evidence does not support the latter hypothesis, as it would require all other lithophile elements with similar volatility to be enriched in the mantle, or for late accretion to be composed of anomalously gallium-rich objects. In order to mitigate this issue, experimental studies have tried to understand how gallium behaves during core segregation by gauging the effects of pressure, temperature and oxygen fugacity on the partitioning of gallium between metal and silicate. None of these parameters provided the first-order change required to match the observation. We investigated the influence of core composition on gallium partitioning. The core in known to contain light-elements (oxygen, silicon sulfur and carbon), and those can change the activity of gallium in the metal, and strongly affect the behavior of gallium during core formation. We performed a series of metal-silicate partitioning experiments (2 GPa, 1673-2073 K) in a piston-cylinder press. We varied the light-element composition of the metal and observed that Si and O have a very strong influence on the activity of gallium, making it more lithophile. We then modeled terrestrial accretion as a continuous process and tested different accretion histories; we can reproduce the mantle concentration of gallium if the core segregates in a deep magma ocean (>40 GPa) and contains large amounts of silicon or oxygen.

  12. Inflammatory pseudotumor: A gallium-avid mobile mesenteric mass

    SciTech Connect

    Auringer, S.T.; Scott, M.D.; Sumner, T.E. (Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC (USA))

    1991-08-01

    An 8-yr-old boy with a 1-mo history of culture-negative fever and anemia underwent gallium, ultrasound, and computed tomography studies as part of the evaluation of a fever of unknown origin. These studies revealed a mobile gallium-avid solid abdominal mass subsequently proven to be an inflammatory pseudotumor of the mesentery, a rare benign mass. This report documents the gallium-avid nature of this rare lesion and discusses associated characteristic clinical, pathologic, and radiographic features.

  13. Atomic gallium laser spectroscopy with violet/blue diode lasers

    E-print Network

    Marago, O M; Gucciardi, P G; Arimondo, E

    2003-01-01

    We describe the operation of two GaN-based diode lasers for the laser spectroscopy of gallium at 403 nm and 417 nm. Their use in an external cavity configuration enabled the investigation of absorption spectroscopy in a gallium hollow cathode. We have analyzed the Doppler broadened profiles accounting for hyperfine and isotope structure and extracting both the temperature and densities of the neutral atomic sample produced in the glow discharge. We have also built a setup to produce a thermal atomic beam of gallium. Using the GaN-based diode lasers we have studied the laser induced fluorescence and hyperfine resolved spectra of gallium.

  14. Determination of gallium originated from a gallium-based anticancer drug in human urine using ICP-MS

    Microsoft Academic Search

    Darya G. Filatova; Irina F. Seregina; Lidia S. Foteeva; Vladimir V. Pukhov; Andrei R. Timerbaev; Mikhail A. Bolshov

    2011-01-01

    Urine analysis gives an insight into the excretion of the administered drug which is related to its reactivity and toxicity.\\u000a In this work, the capability of inductively coupled plasma mass spectrometry (ICP-MS) to measure ultratrace metal levels was\\u000a utilized for rapid assaying of gallium originating from the novel gallium anticancer drug, tris(8-quinolinolato)gallium(III) (GaQ3), in human urine. Sample dilution with 1%

  15. 176Lu-176Hf geochronology of garnet I: experimental determination of the diffusion kinetics of Lu3+ and Hf4+ in garnet, closure temperatures and geochronological implications

    NASA Astrophysics Data System (ADS)

    Bloch, Elias; Ganguly, Jibamitra; Hervig, Richard; Cheng, Weiji

    2015-02-01

    The 176Lu-176Hf and 147Sm-143Nd decay systems are routinely used to determine garnet (Grt)-whole-rock (WR) ages; however, the 176Lu-176Hf age of garnet is typically older than the 147Sm-143Nd age determined from the same aliquots. Here we present experimental data for Lu3+ and Hf4+ diffusion in garnet as functions of temperature, pressure and oxygen fugacity and show that the diffusivity of Hf4+ in almandine/spessartine garnet is significantly slower than that of Lu3+. The diffusive closure temperature ( T C) of Hf4+ is significantly higher than that of Nd3+, and although this property is partly responsible for the observed 176Lu-176Hf and 147Sm-143Nd Grt-WR age discrepancies, the difference between the T C-s of Lu3+ and Hf4+ could lead to apparent Grt-WR 176Lu-176Hf ages that are skewed from the age of Hf4+ closure in garnet. In addition, the slow diffusivity of Hf4+ indicates that the bulk of metamorphic garnets retain a substantial fraction of prograde radiogenic 176Hf throughout peak metamorphic conditions, a phenomenon that further complicates the interpretation of 176Lu-176Hf garnet ages and invalidates the use of analytical T C expressions. We argue that the diffusion of trivalent rare earth elements in garnet becomes much faster when their concentration level falls below a few hundred ppm, as in the experiments of Tirone et al. (Geochim Cosmochim Acta 69: 2385-2398, 2005), and further argue that this low-concentration mechanism is appropriate for modeling the susceptibility of 147Sm-143Nd garnet ages to diffusive resetting.

  16. Production of high-purity gadolinium-153. 2. Removal of samarium, terbium, and microamounts of europium from gadolinium by extraction chromatography

    SciTech Connect

    Mel`nik, M.I.; Karelin, E.A.; Filimonov, V.T. [Research Inst. of Atomic Reactors, Dimitrovgrad (Russian Federation)

    1995-03-01

    Extraction and extraction-chromatographic behavior of Sm, Eu, Gd, and Tb in the system di-2-ethylhexyl hydrogen phosphate (DEHP)-decane-nitric acid has been studied at various concentrations of nitric acid and lanthanide in aqueous phase. The optimal range of nitric acid concentrations for extraction-chromatographic separation of samarium, europium, gadolinium, and terbium has been determined. The influence of gadolinium concentration on distribution of europium and terbium has been examined. At gadolinium content in solution below 50% of the dynamic exchange capacity of the column, the gadolinium distribution coefficient slightly decreases with increasing gadolinium concentration in the initial solution, the distribution factors of the impurity lanthanides remaining virtually unchanged. With further increase in gadolinium content in the initial solution, the gadolinium distribution factor drastically decreases, and {open_quotes}tails{close_quotes} are formed at the expense of increasing fraction of the extracted complex form GdA{sub 3}. These data allowed a conclusion that composition of extracted complexes is different for Sm, Eu, Gd, and Tb. Conditions proposed for extraction-chromatographic purification of gadolinium in the system DEHP-decane-nitric acid provide for removal of impurity lanthanides (samarium, terbium, and microamounts of europium) with the purification factors greater than 100 (Sm, Tb) and about 2 (Eu) at the column charge of up to 50%.

  17. A Gallium multiphase equation of state

    SciTech Connect

    Crockett, Scott D [Los Alamos National Laboratory; Greeff, Carl [Los Alamos National Laboratory

    2009-01-01

    A new SESAME multiphase Gallium equation of state (EOS) has been developed. The equation of state includes three of the solid phases (Ga I, Ga II, Ga III) and a fluid phase (liquid/gas). The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniol data. We also explore the possibility of re-freezing via dynamic means such as isentropic and shock compression.

  18. Wide Band Gap Gallium Phosphide Solar Cells

    Microsoft Academic Search

    Xuesong Lu; Susan Huang; Martin B. Diaz; Nicole Kotulak; Ruiying Hao; Robert Opila; Allen Barnett

    2012-01-01

    Gallium phosphide (GaP), with its wide band gap of 2.26 eV, is a good candidate for the top junction solar cell in a multijunction solar cell system. Here, we design, fabricate, characterize, and analyze GaP solar cells. Liquid phase epitaxy is used to grow the semiconductor layers. Four generations of GaP solar cells are developed and fabricated with each solar

  19. a Gallium Multiphase Equation of State

    NASA Astrophysics Data System (ADS)

    Crockett, Scott D.; Greeff, Carl W.

    2009-12-01

    A new SESAME multiphase Gallium equation of state (EOS) has been developed. It includes three of the solid phases (Ga I, Ga II, Ga III) and a fluid phase (liquid/gas). The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We also explore the possibility of re-freezing via dynamic means such as isentropic and shock compression. We predict an unusual spontaneous spreading of low pressure shocks from STP.

  20. Gallium Nitride Room Temperature ? Particle Detectors

    Microsoft Academic Search

    Lu Min; Zhang Guo-Guang; Fu Kai; Yu Guo-Hao

    2010-01-01

    Gallium Nitride (GaN) room temperature ? particle detectors are fabricated and characterized, whose device structure is Schottky diode. The current-voltage (I – V) measurements reveal that the reverse breakdown voltage of the detectors is more than 200 V owing to the consummate fabrication processes, and that the Schottky barrier and ideal factor of the detectors are 0.64 eV and 1.02,

  1. Gallium Nitride Room Temperature alpha Particle Detectors

    Microsoft Academic Search

    Min Lu; Guo-Guang Zhang; Kai Fu; Guo-Hao Yu

    2010-01-01

    Gallium Nitride (GaN) room temperature alpha particle detectors are fabricated and characterized, whose device structure is Schottky diode. The current-voltage (I - V) measurements reveal that the reverse breakdown voltage of the detectors is more than 200 V owing to the consummate fabrication processes, and that the Schottky barrier and ideal factor of the detectors are 0.64 eV and 1.02,

  2. Gallium Nitride Schottky betavoltaic nuclear batteries

    Microsoft Academic Search

    Min Lu; Guo-guang Zhang; Kai Fu; Guo-hao Yu; Dan Su; Ji-feng Hu

    2011-01-01

    Gallium Nitride (GaN) Schottky betavoltaic nuclear batteries (GNBB) are demonstrated in our work for the first time. GaN films are grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD), and then GaN Schottky diodes are fabricated by normal micro-fabrication process. Nickel with mass number of 63 (63Ni), which emits ? particles, is loaded on the GaN Schottky diodes to

  3. Anisotropic thermal expansion of copper gallium selenide

    Microsoft Academic Search

    P. Kistaiah; Y. C. Venudhar; K. Sathyanarayana Murthy; L. Iyengar; K. V. Krishna Rao

    1981-01-01

    Unit-cell parameters for the chalcopyrite type ternary semiconducting compound copper gallium selenide (CuGaSe2) have been determined accurately, using the least-squares method, for reflections in the range of Bragg angles 64-82 degrees , by the X-ray powder diffraction method. A study of the thermal expansion of the chalcopyrite structure unit-cell of the compound, determined over the temperature range 28-685 degrees C,

  4. Gallium-67 imaging in muscular sarcoidosis

    SciTech Connect

    Edan, G.; Bourguet, P.; Delaval, P.; Herry, J.Y.

    1984-07-01

    A case is presented of sarcoid myopathy in which radiogallium was seen to accumulate in the sites of muscle involvement. Uptake of the radiotracer disappeared following institution of corticosteroid therapy. The exceptional nature of this case contrasts with the high frequency of biopsy evidence of sarcoid granulomas in muscle. Gallium-67 imaging can be used to determine the extent of muscle involvement and, through evaluation of uptake intensity, the degree of disease activity before and after treatment.

  5. High-dose gallium imaging in lymphoma

    SciTech Connect

    Anderson, K.C.; Leonard, R.C.; Canellos, G.P.; Skarin, A.T.; Kaplan, W.D.

    1983-08-01

    The role of gallium-67 imaging in the management of patients with lymphoma, traditionally assessed using low tracer doses and the rectilinear scanner, was assessed when using larger doses (7 to 10 mCi) and a triple-peak Anger camera. Gallium scan results in 51 patients with non-Hodgkin's lymphoma and 21 patients with Hodgkin's disease were compared with simultaneous radiologic, clinical, and histopathologic reports. Subsequent disease course was also evaluated in light of radionuclide findings. Sensitivity and specificity of the scans were 0.90 or greater for both non-Hodgkin's lymphoma and Hodgkin's disease, and overall accuracy by site was 96 percent. Although there are insufficient numbers of pretreatment scans to allow any conclusions, our data suggest that newer approaches to gallium scanning in treated patients are (1) highly specific in all lymphomas and most sensitive in high-grade non-Hodgkin's lymphoma and Hodgkin's disease; (2) valuable in assessing the mediastinum in both non-Hodgkin's lymphoma and Hodgkin's disease; and (3) helpful adjuncts to computed tomographic scanning and ultrasonography in assessing abdominal node disease.

  6. Gadolinium in lutetium fluoride—an electron paramagnetic resonance study

    Microsoft Academic Search

    K. J Guedes; K. Krambrock; J. Y Gesland

    2001-01-01

    Gadolinium (Gd3+) in Czochralski-grown lutetium fluoride (LuF3) has been investigated by electron paramagnetic resonance (EPR). Detailed analysis of the EPR angular dependencies reveals that Gd3+ entered substitutionally for Lu3+ in monoclinic Cs site symmetry. The Lu site seems to be more distorted by the Gd ion as compared to the Y site in YF3. The zero-field splitting of the ground

  7. The safety of gadolinium in patients with stage 3 and 4 renal failure

    Microsoft Academic Search

    Ihsan Ergun; Kenan Keven; Irfan Uruc; Yakup Ekmekci; Basol Canbakan; Ilhan Erden; Oktay Karatan

    2006-01-01

    Background. Although there is a well-documented risk of acute renal failure (ARF) with the iodinated contrast agents, intravenous gadolinium-based con- trast agents are considered non-nephrotoxic and have been widely used for magnetic resonance imaging (MRI). However, debate continues regarding the safety issue of gadolinium, especially in patients with kidney failure. Therefore, we aimed to evaluate the safety of gadolinium in

  8. Epitaxial garnet films by organometallic chemical vapor deposition

    Microsoft Academic Search

    M. E. Cowher; T. O. Sedgwick; J. Landermann

    1974-01-01

    Epitaxial films of Y3Fe5O12, Eu3Fe5O12, (Eu, Y)3Fe5O12, and Er3Fe5O12 l-2m thick have been chemically vapor deposited on GGG and SmGG garnet substrates from 1000C to 1200C in an\\u000a oxygen atmosphere from metal organic source compounds. These source compounds which are used here for the first time in chemical\\u000a vapor deposition are tris 2, 2, 6, 6, tetramethyl 3, 5 heptanedionate

  9. Epitaxial garnet films by organometallic chemical vapor deposition

    Microsoft Academic Search

    M. E. Cowher; T. O. Sedgwick; J. Landermann

    1974-01-01

    Epitaxial films of Y3Fe5O12, Eu3Fe5O12, (Eu, Y)3Fe5O12, and Er3Fe5O12 l-2µm thick have been chemically vapor deposited on GGG and SmGG garnet substrates from 1000°C to 1200°C in an oxygen atmosphere from metal organic source compounds. These source compounds which are used here for the first time in chemical vapor deposition are tris 2, 2, 6, 6, tetramethyl 3, 5 heptanedionate

  10. The compression mechanism of garnets based on in situ observations

    NASA Astrophysics Data System (ADS)

    Dymshits, Anna; Sharygin, Igor; Litasov, Konstantin; Shatskiy, Anton

    2014-05-01

    Previously it was showed that the bulk modulus of garnet is strongly affected by the bulk modulus of the dodecahedra, while compressibility of other individual polyhedra displays no correlation with the compressibility of the structure as a whole (Milman et al., 2001). If so, Na-majorite (Na-maj) would have the smallest bulk modulus of all silicate garnets, as a phase with a predicted dodecahedral bulk modulus of approximately 70 GPa (Hazen et al., 1994). In fact Na-maj has the largest bulk modulus among the silicate garnets. This behavior must reflect the all-mineral framework of Na-maj with very small cell volume and silicon in the octahedral position. Thus, we conclude that not only the dodecahedral sites, but also the behavior of the garnet framework and relative sizes of the 8- and 6-coordinated cations, control garnet compression. The octahedral site in Na-maj is quite small (1.79 Å) and contains only silicon in comparison to the pyrope (1.85 Å) or majorite (1.88 Å). The small and highly charged octahedra shares four edges with the dodecahedra and thus restrict the volume of the large and low charged dodecahedra. In spite Na-maj has a large average X-cation radius (RNa = 1.07 Å) its dodecahedral volume is relatively small (V = 21.23 and 21.26 Å3). Pacalo et al. (1992) suggested that XO8 polyhedra act as braces and controls the amount of rotation between tetrahedra and octahedra within the corner-linked chains. In case of pyrope XO8 cite is not filled up and polyhedra within the corner-linked chains can rotate freely to accommodate applied stress. In case of Na-maj the dodecahedral site is filled up and rotational freedom is minimized. The dodecahedral site in knorringite (Knr) contains cation with a small radius (Mg-O = 2.22 and 2.34 Å), so XO8 polyhedra is not filled up and can rotate freely to accommodate applied stress. In case of uvarovite not only octahedral but the dodecahedral site is also large (Ca-O = 2.35 and 2.51 Å), so the rotational freedom is minimized and such relations between the XO8 and YO6 sites provide evidence for comparatively more rigid structure. In case of uvarovite the bulk modulus is 162 GPa (Leger et al., 1990), while for Knr we obtain 154 GPa. Such relations between the XO8 and YO6 sites provide evidence for comparatively more rigid structure. As a result, Na-maj with all octahedral sites occupied by silicon has the largest value of the bulk modulus among garnets. It would be interesting to study compressibility of Li-majorite expressed by Yang et al. (2009). That phase has smaller cell volume (1430 Å3) and X-O distance (2.26 Å) but the same YO6 polyhedra fully occupied by silicon. The study was supported by Ministry of Education and Science of Russian Federation, project Nos 14.B25.31.0032, MK-265.2014.5, Russian Foundation for Basic Research No 14-05-00957-a. Hazen, R.M., Downs, R.T., Conrad, P.G., Finger, L.W., Gasparik, T. Comparative compressibilities of majorite-type garnets // Physics and Chemistry of Minerals, 1994, v.21, p.344-349. Leger, J., Redon, A., Chateau, C. Compressions of synthetic pyrope, spessartine and uvarovite garnets up to 25 GPa // Physics and Chemistry of Minerals, 1990, v.17, p.161-167. Milman, V., Akhmatskaya, E., Nobes, R., Winkler, B., Pickard, C., White, J. Systematic ab initio study of the compressibility of silicate garnets // Acta Crystallographica Section B: Structural Science, 2001, v.57, p.163-177. Yang, H., Konzett, J., Frost, D.J., Downs, R.T. X-ray diffraction and Raman spectroscopic study of clinopyroxenes with six-coordinated Si in the Na(Mg0.5Si0.5)Si2O6-NaAlSi2O6 system // American Mineralogist, 2009, v.94, p.942-949.

  11. Silicon ring isolators with bonded nonreciprocal magneto-optic garnets.

    PubMed

    Tien, Ming-Chun; Mizumoto, Tetsuya; Pintus, Paolo; Kromer, Herbert; Bowers, John E

    2011-06-01

    A ring isolator is demonstrated for the first time by directly bonding a cerium-substituted yttrium iron garnet (Ce:YIG) onto a silicon ring resonator using oxygen plasma enhanced bonding. The silicon waveguide is 600 nm wide and 295 nm thick with 500-nm-thick Ce:YIG on the top to have reasonable nonreciprocal effect and low optical loss. With a radial magnetic field applied to the ring isolator, it exhibits 9-dB isolation at resonance in the 1550 nm wavelength regime. PMID:21716405

  12. Reply to comment on "The applicability of garnet — orthopyroxene geobarometry in mantle xenoliths" by Paolo Nimis and Herman Grütter

    NASA Astrophysics Data System (ADS)

    Wu, Chun-Ming; Zhao, Guochun

    2012-06-01

    Equilibrium P-T conditions of garnet-facies or garnet-spinel transition facies mantle xenoliths are suggested to be best determined through a combination of the Taylor (1998) two-pyroxene thermometer either with the Taylor (1998) garnet-orthopyroxene barometer for TiO2-rich orthopyroxenes (Al/Ti < 12.0), or with the Nickel and Green (1985) garnet-orthopyroxene barometer for TiO2-poor orthopyroxenes (Al/Ti > 12.0).

  13. Titanian clinohumite–garnet–pyroxene rock from the SuLu UHP metamorphic terrane, China: chemical evolution and tectonic implications

    Microsoft Academic Search

    Jian-Jun Yang

    2003-01-01

    A garnet–pyroxene rock containing abundant Ti-clinohumite (ca. 40 vol.%) occurs along with eclogites as small blocks in quartzo-feldsparthic gneiss in the southern end of the Chinese Su-Lu ultrahigh-pressure (UHP) metamorphic terrane. It consists of three aggregates: (1) Ti-clinohumite-dominated aggregate with interstitial garnet and pyroxene, (2) garnet+pyroxene aggregate with Ti-clinohumite inclusions, and (3) Ti-clinohumite-free aggregate dominated by garnet. Apatite, phlogopite, zircon,

  14. Interactions of zircaloy cladding with gallium -- 1997 status

    Microsoft Academic Search

    D. F. Wilson; J. R. DiStefano; J. F. King; E. T. Manneschmidt; J. P. Strizak

    1997-01-01

    A four phase program has been implemented to evaluate the effect of gallium in mixed oxide (MOX) fuel derived from weapons grade (WG) plutonium on Zircaloy cladding performance. The objective is to demonstrate that low levels of gallium will not compromise the performance of the MOX fuel system in LWR. This graded, four phase experimental program will evaluate the performance

  15. Gallium scintigraphy in bone infarction. Correlation with bone imaging

    SciTech Connect

    Armas, R.R.; Goldsmith, S.J.

    1984-01-01

    The appearance of gallium-67 images in bone infarction was studied in nine patients with sickle cell disease and correlated with the bone scan findings. Gallium uptake in acute infarction was decreased or absent with a variable bone scan uptake, and normal in healing infarcts, which showed increased uptake on bone scan. The significance of these findings is discussed.

  16. Early Gallium-67 abdominal imaging: pitfalls due to bowel activity

    SciTech Connect

    Perkins, P.J.

    1981-05-01

    In gallium scanning for abdominal inflammatory disease, early imaging has been advocated so physiological activity within the bowel will not be confused with pathologic uptake. The normal physiologic pattern of bowel uptake is not desribed in the literature. Our study was undertaken to evaluate the frequency and patterns of gallium-67 bowel activity which may occur when early imaging is performed.

  17. Garnet Yield Strength at High Pressures and Implications for Upper Mantle and Transition Zone Rheology

    SciTech Connect

    Kavner,A.

    2008-01-01

    Garnet helps control the mechanical behavior of the Earth's crust, mantle, and transition zone. Here, measurements are presented suggesting that garnet, long considered to be a high-viscosity phase, is actually weaker than the other dominant components in the transition zone. The mechanical behavior of garnet at high pressures was examined using radial diffraction techniques in the diamond anvil cell. The yield strength of grossular garnet was inferred from synchrotron X-ray measurements of differential lattice strains. The differential stress was found to increase from 1.3 ({+-}0.6) GPa at a hydrostatic pressure 5.8 ({+-}1.1) GPa to 4.1 ({+-}0.4) GPa at 15.7 ({+-}1.0) GPa, where it was level to 19 GPa. The strength results are consistent with inferred strength values for majorite garnet from measurements in the diamond cell normal geometry, bolstering the idea that garnet-structured materials may all have similar strengths. In this low-temperature, high differential stress regime, garnet is shown to be significantly weaker than anhydrous ringwoodite and to have a strength similar to hydrous ringwoodite. This result suggests that the presence of water in the transition zone may not be required to explain a weak rheology, and therefore models of transition zone behavior built assuming that garnet is the high-strength phase may need to be revised.

  18. High-temperature thermal expansion and elasticity of calcium-rich garnets

    Microsoft Academic Search

    Donald G. Isaak; Orson L. Anderson; Hitoshi Oda

    1992-01-01

    We present new high temperature elasticity data on two grossular garnet specimens. One specimen is single-crystal, of nearly endmember grossular, the other is polycrystalline with about 22% molar andradite. Our data extend the high temperature regime for which any garnet elasticity data are available from 1000 to 1350 K and the compositional range of temperature data to near endmember grossular.

  19. Transformation of two-pyroxene hornblende granulite to garnet granulite involving simultaneous melting and fracturing of

    E-print Network

    Daczko, Nathan

    and planar garnet reaction zones in rectilinear patterns. In gabbroic gneiss, narrow dykes of anorthositic that recrystallization was mostly isochemical. The anorthositic veins cut contacts between gabbroic gneiss and dioritic gneiss, but change in morphology at the contacts, from the anorthositic vein surrounded by a garnet

  20. Magnetocrystalline anisotropy of ytterbium iron garnet Yb3Fe5O12

    Microsoft Academic Search

    R F Pearson

    1965-01-01

    The anisotropy of ytterbium iron garnet and ytterbium-doped yttrium iron garnet has been measured by the torque method in applied fields of 15 000 Oe at temperatures between 1.5 °K and 300 °K. Theoretical values of the anisotropy were calculated from optical energy level data derived by other workers and these were compared with the experimental results. At temperatures below

  1. Geothermobarometry in albite-garnet orthogneisses: A case study from the Gran Paradiso nappe (Western Alps)

    NASA Astrophysics Data System (ADS)

    Le Goff, Elisabeth; Ballèvre, Michel

    1990-11-01

    The aim of this paper is to estimate syntectonic P- T conditions within albite- and garnet-bearing orthogneisses. These rocks are generally characterized by the assemblage quartz + albite + biotite + phengite + CaFe-garnet + epidote + titanite. Garnet contains up to 55 mole per cent of grossular. K-feldspar is a relict magmatic phase. P- T conditions are estimated using several independent methods. First, it is shown that exchange reactions based on the Fe?Mg partitioning between garnet and biotite or garnet and phengite cannot be used to estimate temperatures in these rocks, due to the high grossular content of garnet. Second, maximum and minimum pressures are constrained, respectively, by the occurrence of albite instead of jadeite + quartz and by the assemblage phengite + biotite + quartz. Third, phase equilibria in albite- and garnet-bearing metagranites are modelled in the system K 2O?CaO?FeO?Al 2O 3?SiO 2?H 2O. Equilibrium curves are calculated for the observed phase compositions. Uncertainties in P- T estimates mainly result from the choice of appropriate non-ideal solution models for the garnet. An application is developed for granites from the Gran Paradiso nappe (Western Alps). These granites show an heterogeneous deformation of Alpine age expressed by mylonitic shear zones cutting across weakly deformed domains. Estimated P- T conditions for the synkinematic assemblages are 10-16 kbar at 550±50°C.

  2. Nuclear microprobe imaging of gallium nitrate in cancer cells

    NASA Astrophysics Data System (ADS)

    Ortega, Richard; Suda, Asami; Devès, Guillaume

    2003-09-01

    Gallium nitrate is used in clinical oncology as treatment for hypercalcemia and for cancer that has spread to the bone. Its mechanism of antitumor action has not been fully elucidated yet. The knowledge of the intracellular distribution of anticancer drugs is of particular interest in oncology to better understand their cellular pharmacology. In addition, most metal-based anticancer compounds interact with endogenous trace elements in cells, altering their metabolism. The purpose of this experiment was to examine, by use of nuclear microprobe analysis, the cellular distribution of gallium and endogenous trace elements within cancer cells exposed to gallium nitrate. In a majority of cellular analyses, gallium was found homogeneously distributed in cells following the distribution of carbon. In a smaller number of cells, however, gallium appeared concentrated together with P, Ca and Fe within round structures of about 2-5 ?m diameter located in the perinuclear region. These intracellular structures are typical of lysosomial material.

  3. The Preparation and Structural Characterization of Three Structural Types of Gallium Compounds Derived from Gallium (II) Chloride

    NASA Technical Reports Server (NTRS)

    Gordon, Edward M.; Hepp, Aloysius F.; Duraj. Stan A.; Habash, Tuhfeh S.; Fanwick, Phillip E.; Schupp, John D.; Eckles, William E.; Long, Shawn

    1997-01-01

    The three compounds Ga2Cl4(4-mepy)2 (1),[GaCl2(4-mepy)4]GaCl4x1/2(4-mepy); (2) and GaCl2(4-mepy)2(S2CNEt2); (3) (4-mepy= 4-methylpyridine) have been prepared from reactions of gallium (II) chloride in 4-methylpyridine and characterized by single-crystal X-ray analysis. Small variations in the reaction conditions for gallium(II) chloride can produce crystals with substantially different structural properties. The three compounds described here encompass a neutral gallium(II) dimer in which each gallium is four-coordinate, an ionic compound containing both anionic and cationic gallium complex ions with different coordination numbers and a neutral six-coordinate heteroleptic

  4. The use of trace element zoning patterns in garnet to infer reaction paths of metamorphic rocks

    NASA Astrophysics Data System (ADS)

    Konrad-Schmolke, Matthias; Witte, Clemens; Dohmen, Ralf; O'Brien, Patrick; Erpel, Lars; Halama, Ralf; Schmidt, Alexander; Ditterova, Hana

    2015-04-01

    Garnet is one of the most versatile minerals in metamorphic petrology. It is stable over a large pressure and temperature range and thus occurs in many metamorphic environments. Garnet has a wide range of chemical compositions and its major and trace element composition well reflects the pressure (P), temperature (T) and chemical conditions (X) as well as the element transport kinetic properties of the host rock during growth. Hence, compositional growth zonations in garnet contain information about most geochemical, mineralogical and petrological properties of metamorphic rocks. However, detailed interpretation of complex zoning patterns in metamorphic garnet was hindered mainly by the lack of knowledge about the various contributions of kinetic and equilibrium effects to the trace element incorporation into garnet. In this contribution we combine thermodynamic equilibrium calculations together with mass balanced trace element distribution among coexisting phases with diffusion models that simulate kinetically controlled element transport in a reacting host rock. Comparison of the model results with natural garnets enables detailed interpretation of commonly observed major and trace element patterns in high-pressure (HP) and ultra-high pressure (UHP) garnets in terms of reaction paths and physico-chemical properties of the host rock. The comparison of our numerical models with a series of well-investigated (U)HP samples shows that the kinetic influence on rare earth element incorporation into garnet is limited in most rocks at the early stages of garnet growth and increases with increasing grade of rock transformation. We show that REE zoning patterns can be used to distinguish between cold (lawsonite-stable) and warm (epidote-stable) prograde reaction paths. REE liberation along a warm P-T trajectory occurs in three breakdown reactions involving chlorite, epidote and amphibole. All three reactions result in characteristic heavy (HREE) and medium (MREE) REE growth patterns in garnet reflecting the contrasting partition of REE among garnet and the reacting mineral matrix. In contrast, REE liberation along a cold trajectory is predominantly controlled by the breakdown of amphibole, which produces a pronounced incorporation of both HREE and MREE in the rims of the growing garnet. Chromium concentration variations in garnet are also an excellent source of information about the reaction path. The Cr distribution in garnet cores from different UHP samples clearly reflects the prograde transformation of magmatic clinopyroxene into garnet+omphacite. The formation of garnet from omphacite at UHP conditions is indicated by concentric Cr (and REE) enrichments in the outermost rims of the garnet porphyroblasts. We would like to emphasise that detailed investigation and interpretation of trace element patterns in metamorphic garnet gives important insight into the reaction path of the host rock, which in turn has crucial implications for the interpretation of geochronological data from metamorphic garnets.

  5. Ages of Sevier thrusting from dating of metamorphic garnet using the Lu-Hf method

    NASA Astrophysics Data System (ADS)

    Cruz-Uribe, A. M.; Hoisch, T. D.; Wells, M. L.; Vervoort, J. D.

    2008-12-01

    Combined thermodynamic modeling of garnet growth zoning and Lu-Hf dating of garnet yield well-constrained pressure-temperature-time (PTt) paths. Here we present PTt paths from amphibolite-facies pelitic garnet from the Raft River-Albion-Grouse Creek metamorphic core complex that constrain the timing of thrusting in the hinterland of the Sevier thrust belt. Three general times of thrust burial are indicated: 150, 138, and 85 Ma. Lu-Hf garnet dating of burial-related garnet growth in the Raft River Mountains yielded a Late Jurassic age of 149.9 ± 1.2 Ma (2?, MSWD = 1.1) based on three garnet fractions and a whole rock. A PT path from the schist of Mahogany Peaks in the Albion Range, Idaho, records an isothermal pressure increase indicating growth during thrusting. Lu-Hf dating of garnet from the same rock yielded an Early Cretaceous age of 138.7 ± 0.7 Ma (2?, MSWD = 1.6) based on seven garnet fractions. An additional PT path from a nearby outcrop also records an isothermal pressure increase and a similar Lu-Hf garnet age of 132.1 ± 5.1 Ma (2?, MSWD = 9.5) based on three garnet fractions and a whole rock. PT paths of multiple garnet grains from the schist of Stevens Spring in the Grouse Creek Mountains, Utah, exhibit isothermal pressure increases and yielded a Lu-Hf garnet age of 85.5 ± 1.9 Ma (2?, MSWD = 3.9) based on five garnet fractions and a whole rock. The Late Jurassic burial event recorded in the Raft River Mountains is older than the ages of inception of thrusting of the western thrusts of the Sevier fold-thrust belt including the Canyon Range and Paris - Willard thrusts, but consistent with an eastward progression in initial shortening in the orogenic wedge and development of an inferred thrust load responsible for the retroarc Morrison Formation basin. Early Cretaceous hinterland burial recorded in the Albion Range is permissively coeval with activity on the Willard and Canyon Range thrusts. Finally, renewed hinterland thrust burial during the Late Cretaceous, as documented in the Grouse Creek Mountains, is consistent in timing with previous interpretations of major thrusting in frontal thrust systems of the Sevier belt, such as the development of the Absaroka thrust.

  6. Resonant cavity modes in gallium oxide microwires

    NASA Astrophysics Data System (ADS)

    López, Iñaki; Nogales, Emilio; Méndez, Bianchi; Piqueras, Javier

    2012-06-01

    Fabry Perot resonant modes in the optical range 660-770 nm have been detected from single and coupled Cr doped gallium oxide microwires at room temperature. The luminescence is due to chromium ions and dominated by the broad band involving the 4T2-4A2 transition, strongly coupled to phonons, which could be of interest in tunable lasers. The confinement of the emitted photons leads to resonant modes detected at both ends of the wires. The separation wavelength between maxima follows the Fabry-Perot dependence on the wire length and the group refractive index for the Ga2O3 microwires.

  7. Distributed feedback gallium nitride nanowire lasers

    NASA Astrophysics Data System (ADS)

    Wright, Jeremy B.; Campione, Salvatore; Liu, Sheng; Martinez, Julio A.; Xu, Huiwen; Luk, Ting S.; Li, Qiming; Wang, George T.; Swartzentruber, Brian S.; Lester, Luke F.; Brener, Igal

    2014-01-01

    Achieving single-mode laser operation in nanowire lasers remains a challenge due to a lack of mode selection approaches. We have implemented single-mode lasing using distributed feedback by externally coupling gallium nitride nanowires to a dielectric grating to achieve mode-control. The effective periodicity of the grating experienced by the nanowire was altered using nanomanipulation to change the angular alignment between the nanowire and the grating. The effective periodicity controls the spectral location of the distributed feedback stop-band. Single-mode emission was achieved at an alignment, where the designed periodicity of the grating was experienced by the nanowire.

  8. Gallium-67 imaging in muscular sarcoidosis

    SciTech Connect

    Edan, G.; Bourguet, P.; Delaval, P.; Herry, J.Y.

    1984-07-01

    A case is presented of sarcoid myopathy in which radiogallium was seen to accumulate in the sites of muscle involvement. Uptake of the radiotracer disappeared following institution of corticosteroid therapy. The exceptional nature of this case contrasts with the high frequency of biopsy evidence of sarcoid muscle disease but is consistent with the rarity of clinical evidence of sarcoid granulomas in muscle. Gallium-67 imaging can be used to determine the extent of muscle involvement and, through evaluation of uptake intensity, the degree of disease activity before and after treatment.

  9. Behavior of Zircaloy Cladding in the Presence of Gallium

    SciTech Connect

    DiStefano, J.R.; King, J.F.; Manneschmidt, E.T.; Strizak, J.P.; Wilson, D.F.

    1998-09-28

    The U.S. Department of Energy has established a dual-track approach to the disposition of plutonium arising from the dismantling of nuclear weapons. Both immobilization and reactor-based mixed-oxide (MOX) fuel technologies are being evaluated. The reactor-based MOX fuel option requires assessment of the potential impact of concentrations of gallium (on the order of 1 to 10 ppm), not present in conventional MOX fuel, on cladding material performance. An experimental program was designed to evaluate the performance of prototypic Zircaloy cladding materials against (1) liquid gallium, and (2) various concentrations of G~03. Three types of tests were performed: (1) corrosion, (2) liquid metal embrittlement, and (3) corrosion-mechanical. These tests were to determine corrosion mechanisms, thresholds for temperature and concentration of gallium that delineate behavioral regimes, and changes in the mechanical properties of Zircaloy. Results have generally been favorable for the use of weapons-grade (WG) MOX fhel. The Zircaloy cladding does react with gallium to form intermetallic compounds at >3000 C; however, this reaction is limited by the mass of gallium and is therefore not expected to be significant with a low level (parts per million) of gallium in the MOX fuel. Furthermore, no evidence for grain boundary penetration by gallium or liquid metal embrittlement was observed.

  10. Lithospheric roots beneath western Laurentia: The geochemical signal in mantle garnets

    USGS Publications Warehouse

    Canil, D.; Schulze, D.J.; Hall, D.; Hearn, B.C., Jr.; Milliken, S.M.

    2003-01-01

    This study presents major and trace element data for 243 mantle garnet xenocrysts from six kimberlites in parts of western North America. The geochemical data for the garnet xenocrysts are used to infer the composition, thickness, and tectonothermal affinity of the mantle lithosphere beneath western Laurentia at the time of kimberlite eruption. The garnets record temperatures between 800 and 1450??C using Ni-in-garnet thermometry and represent mainly lherzolitic mantle lithosphere sampled over an interval from about 110-260 km depth. Garnets with sinuous rare-earth element patterns, high Sr, and high Sc/V occur mainly at shallow depths and occur almost exclusively in kimberlites interpreted to have sampled Archean mantle lithosphere beneath the Wyoming Province in Laurentia, and are notably absent in garnets from kimberlites erupting through the Proterozoic Yavapai Mazatzal and Trans-Hudson provinces. The similarities in depths of equilibration, but differing geochemical patterns in garnets from the Cross kimberlite (southeastern British Columbia) compared to kimberlites in the Wyoming Province argue for post-Archean replacement and (or) modification of mantle beneath the Archean Hearne Province. Convective removal of mantle lithosphere beneath the Archean Hearne Province in a "tEctonic vise" during the Proterozoic terminal collisions that formed Laurentia either did not occur, or was followed by replacement of thick mantle lithosphere that was sampled by kimberlite in the Triassic, and is still observed there seismically today.

  11. Ilmenite Exsolution in Xenolithic Garnets From the Hawaiian Hot Spot: Evidence for the Existance of High-titanium Garnets in the Earth's Mantle

    NASA Astrophysics Data System (ADS)

    Keshav, S.; Sowerby, J. R.; Sen, G.

    2001-12-01

    Oxide inclusions in a pyrope host were discovered in a single garnet clinopyroxenite xenolith (sample 115954-20 B; Jackson Collection, Smithsonian) from Salt Lake Crater, Oahu, Hawaii. These inclusions, ~ 5-6 ? m thick and 10 ? m long, appear to radiate from a point, rather than align along the <111> direction, as found previously by other authors (e.g., Haggerty, 1991b). In the same section there are other garnet grains that have ilmenite of the same morphology but along <111>. Electron microprobe analysis and Raman spectroscopy show that both types of inclusions are ilmenite (FeTiO3) with a large geikelite (MgTiO3) component, and minor amounts of Al3+, Cr3+, and Fe3+. Note that ilmenite does not occur as a discrete phase in the xenolith. Inclusions of ilmenite and rutile, have previously been found in host garnets from eclogitic and lherzolitic xenoliths in kimberlites and ultra-high pressure terrains. This is the first report of such occurrence from an oceanic hot spot source. Based on texture, we suggest that the ilmenite inclusions in garnet in the Hawaiian xenolith are of exsolution origin as opposed to an origin by epitaxal precipitation (as proposed by Wang et al, 1999). At the present time, because of the lack of appropriate experimental study it is difficult to speculate on the P,T conditions under which ilmenite exsolved from the garnet host. However, Van Roermund et al (2000) have hypothesized on crystal chemical grounds that such inclusions are the result of the break down of a high P,T `super-titanic' garnet to a lower P,T pyrope with exsolved ilmenite, in a similar fashion to the breakdown of `super-silicic' or majoritic garnet to pyrope with exsolved pyroxene.

  12. P- and S-wave velocities of the lowermost crustal rocks from the Kohistan arc: Implications for seismic Moho discontinuity attributed to abundant garnet

    Microsoft Academic Search

    Yoshio Kono; Masahiro Ishikawa; Yumiko Harigane; Katsuyoshi Michibayashi; Makoto Arima

    2009-01-01

    P- (Vp) and S-wave (Vs) velocities of garnet-free (two-pyroxene granulite) and garnet-bearing (garnet granulite and garnet pyroxenite) lowermost crustal rocks collected from the Kohistan arc, northern Pakistan, were measured at 0.1–1.0 GPa and 25–400 °C. Garnet granulite had higher Vp (+0.31 km\\/s) and Vs (+0.27 km\\/s) than two-pyroxene granulite. Although Vp and Vs increased with increasing volume percent of garnet, plagioclase-free garnet pyroxenite showed

  13. Doped gallium oxide nanowires for photonics

    NASA Astrophysics Data System (ADS)

    Nogales, E.; López, I.; Méndez, B.; Piqueras, J.; Lorenz, K.; Alves, E.; García, J. A.

    2012-02-01

    Monoclinic gallium oxide, ?-Ga2O3, is a transparent conducting oxide (TCO) that presents one of the widest band gaps among this family of materials. Its characteristics make it highly interesting for applications in UV - visible - IR optoelectronic and photonic devices. On the other hand, the morphology of nanowires made of this oxide presents specific advantages for light emitting nanodevices, waveguides and gas sensors. Control of doping of the nanostructures is of the utmost importance in order to tailor the behavior of these devices. In this work, the growth of the nanowires is based on the vapor-solid (VS) mechanism during thermal annealing treatment while the doping process was carried out in three different ways. In one of the cases, doping was obtained during the growth of the wires. A second method was based on thermal diffusion of the dopants after the growth of undoped nanowires, while the third method used ion implantation to introduce optically active ions into previously grown nanowires. The study of the influence of the different dopants on the luminescence properties of gallium oxide nanowires is presented. In particular, transition metals and rare earths such as Cr, Gd, Er or Eu were used as optically active dopants that allowed selection of the luminescence wavelength, spanning from the UV to the IR ranges. The benefits and drawbacks of the three different doping methods are analyzed. The waveguiding behavior of the doped nanowires has been studied by room temperature micro-photoluminescence.

  14. Characterization of semi-insulating gallium arsenide

    NASA Astrophysics Data System (ADS)

    Blakemore, John S.

    1991-08-01

    This project was established for the purpose of characterization of samples from melt grown single crystals of nominally undoped gallium arsenide, primarily such crystals as grown by the vertical zone melt (VZM) method at the Naval Research Laboratory. During this period electrical and optical samples were measured for 13 of these VZM-grown gallium arsenide. Measurements made at Western Washington University (WWU) under the terms of this project were in accordance with the Statement of Work provided at the project's outset: including near-infrared transmittance measurements for determination of neutral and ionized EL2 center concentrations, local vibrational mode (LVM) measurements in the mid-IR relative to carbon impurities, and measurements of dc electrical transport properties versus temperature. A program for growth of GaAs and other semiconductors by the VZM method began at NRL several years ago, and the practicality of this method for growing semi-insulating (SI) nominally undoped GaAs in a pBN crucible was demonstrated by Swiggard (1989) and in various subsequent papers.

  15. Machining of iron-gallium for microactuator

    NASA Astrophysics Data System (ADS)

    Ueno, Toshiyuki; Summers, Eric; Higuchi, Toshiro

    2006-03-01

    We investigate the machining properties of Iron-Gallium alloy for microactuator. Iron-Gallium is ductile magnetostrictive material with moderate magnetostriction ranging from 100 to 300ppm. The microactuator of Fe-Ga is expected to have advantages of simple configuration, low voltage driving, high robustness against external force and high temperature environment, compared with that of PZT. Here the rod of Fe-Ga prepared by FSZM technique was machined to distributed pillars of 1mm square by milling process. The comparison of magnetostrictions of machined and non-machined parts by strain gage confirms the strains different in pillars are inherited from the grain distribution and the milling process does not significantly deteriorate the material properties. The measurement of displacements by LASER Doppler vibrometer supports the validity of strain measurement. The success of the fabrication of the distributed pillars of 0.7 and 0.5mm square exhibits the potential of the milling process for Fe-Ga with high aspect ratio suitable for practical micro applications.

  16. Gadolinium nanoparticles and contrast agent as radiation sensitizers.

    PubMed

    Taupin, Florence; Flaender, Mélanie; Delorme, Rachel; Brochard, Thierry; Mayol, Jean-François; Arnaud, Josiane; Perriat, Pascal; Sancey, Lucie; Lux, François; Barth, Rolf F; Carrière, Marie; Ravanat, Jean-Luc; Elleaume, Hélène

    2015-06-01

    The goal of the present study was to evaluate and compare the radiosensitizing properties of gadolinium nanoparticles (NPs) with the gadolinium contrast agent (GdCA) Magnevist(®) in order to better understand the mechanisms by which they act as radiation sensitizers. This was determined following either low energy synchrotron irradiation or high energy gamma irradiation of F98 rat glioma cells exposed to ultrasmall gadolinium NPs (GdNPs, hydrodynamic diameter of 3?nm) or GdCA. Clonogenic assays were used to quantify cell survival after irradiation in the presence of Gd using monochromatic x-rays with energies in the 25?keV-80?keV range from a synchrotron and 1.25 MeV gamma photons from a cobalt-60 source. Radiosensitization was demonstrated with both agents in combination with X-irradiation. At the same concentration (2.1?mg?mL(-1)), GdNPS had a greater effect than GdCA. The maximum sensitization-enhancement ratio at 4?Gy (SER4Gy) was observed at an energy of 65?keV for both the nanoparticles and the contrast agent (2.44???±???0.33 and 1.50???±???0.20, for GdNPs and GdCA, respectively). At a higher energy (1.25?MeV), radiosensitization only was observed with GdNPs (1.66???±???0.17 and 1.01???±???0.11, for GdNPs and GdCA, respectively). The radiation dose enhancements were highly 'energy dependent' for both agents. Secondary-electron-emission generated after photoelectric events appeared to be the primary mechanism by which Gd contrast agents functioned as radiosensitizers. On the other hand, other biological mechanisms, such as alterations in the cell cycle may explain the enhanced radiosensitizing properties of GdNPs. PMID:25988839

  17. Gadolinium nanoparticles and contrast agent as radiation sensitizers

    NASA Astrophysics Data System (ADS)

    Taupin, Florence; Flaender, Mélanie; Delorme, Rachel; Brochard, Thierry; Mayol, Jean-François; Arnaud, Josiane; Perriat, Pascal; Sancey, Lucie; Lux, François; Barth, Rolf F.; Carrière, Marie; Ravanat, Jean-Luc; Elleaume, Hélène

    2015-06-01

    The goal of the present study was to evaluate and compare the radiosensitizing properties of gadolinium nanoparticles (NPs) with the gadolinium contrast agent (GdCA) Magnevist® in order to better understand the mechanisms by which they act as radiation sensitizers. This was determined following either low energy synchrotron irradiation or high energy gamma irradiation of F98 rat glioma cells exposed to ultrasmall gadolinium NPs (GdNPs, hydrodynamic diameter of 3?nm) or GdCA. Clonogenic assays were used to quantify cell survival after irradiation in the presence of Gd using monochromatic x-rays with energies in the 25?keV–80?keV range from a synchrotron and 1.25 MeV gamma photons from a cobalt-60 source. Radiosensitization was demonstrated with both agents in combination with X-irradiation. At the same concentration (2.1?mg?mL?1), GdNPS had a greater effect than GdCA. The maximum sensitization-enhancement ratio at 4?Gy (SER4Gy) was observed at an energy of 65?keV for both the nanoparticles and the contrast agent (2.44???±???0.33 and 1.50???±???0.20, for GdNPs and GdCA, respectively). At a higher energy (1.25?MeV), radiosensitization only was observed with GdNPs (1.66???±???0.17 and 1.01???±???0.11, for GdNPs and GdCA, respectively). The radiation dose enhancements were highly ‘energy dependent’ for both agents. Secondary-electron-emission generated after photoelectric events appeared to be the primary mechanism by which Gd contrast agents functioned as radiosensitizers. On the other hand, other biological mechanisms, such as alterations in the cell cycle may explain the enhanced radiosensitizing properties of GdNPs.

  18. Measurement of the solar neutrino capture rate with gallium metal

    SciTech Connect

    SAGE Collaboration

    1999-11-01

    The solar neutrino capture rate measured by the Russian-American Gallium Experiment (SAGE) on metallic gallium during the period January 1990 through December 1997 is 67.2{sub {minus}7.0{minus}3.0}{sup +7.2+3.5} SNU, where the uncertainties are statistical and systematic, respectively. This represents only about half of the predicted standard solar model rate of 129 SNU. All the experimental procedures, including extraction of germanium from gallium, counting of {sup 71}Ge, and data analysis, are discussed in detail. {copyright} {ital 1999} {ital The American Physical Society}

  19. Correlation by Rb-Sr geochronology of garnet growth histories from different structural levels within the Tauern Window, Eastern Alps

    NASA Astrophysics Data System (ADS)

    Christensen, John N.; Selverstone, Jane; Rosenfeld, John L.; Depaolo, Donald J.

    1994-03-01

    In order to evaluate rates of tectonometamorphic processes, growth rates of garnets from metamorphic rocks of the Tauern Window, Eastern Alps were measured using Rb-Sr isotopes. The garnet growth rates were determined from Rb-Sr isotopic zonation of single garnet crystals and the Rb-Sr isotopic compositions of their associated rock matrices. Garnets were analyzed from the Upper Schieferhülle (USH) and Lower Schieferhülle, (LSH) within the Tauern Window. Two garnets from the USH grew at rates of 0.67{-0.13/+0.19}mm/million years and 0.88{-0.19/+0.34}mm/million years, respectively, indicating an average growth duration of 5.4±1.7 million years. The duration of growth coupled with the amount of rotation recorded by inclusion trails in the USH garnets yields an average shear-strain rate during garnet growth of 2.7{-0.7/+1.2}×10-14 s-1. Garnet growth in the sample from the USH occurred between 35.4±0.6 and 30±0.8 Ma. The garnet from the LSH grew at a rate of 0.23±0.015 mm/million years between 62±1.5 Ma and 30.2±1.5 Ma. Contemporaneous cessation of garnet growth in both units at ˜30 Ma is in accord with previous dating of the thermal peak of metamorphism in the Tauern Window. Correlation with previously published pressure-temperature paths for garnets from the USH and LSH yields approximate rates of burial, exhumation and heating during garnet growth. Assuming that these P — T paths are applicable to the garnets in this study, the contemporaneous exhumation rates recorded by garnet in the USH and LSH were approximately 4{-2/+3}mm/year and 2±1 mm/year, respectively.

  20. Magnetoresistance of polycrystalline gadolinium with varying grain size

    NASA Astrophysics Data System (ADS)

    Chakravorty, Manotosh; Raychaudhuri, A. K.

    2015-01-01

    In this paper, we report a study of evolution of low field magnetoresistance (MR) of Gadolinium as the grain size in the sample is changed from few microns (˜4 ?m) to the nanoscopic regime (˜35 nm). The low field MR has a clear effect on varying grain size. In large grain sample (few ?m), the magnetic domains are controlled by local anisotropy field determined mainly by the magnetocrystalline anisotropy. The low field MR clearly reflects the temperature dependence of the magnetocrystalline anisotropy. For decreasing gain size, the contribution of spin disorder at the grain boundary increases and enhances the local anisotropy field.

  1. Phosphorus contents in garnet from an ultrahigh pressure, high-temperature eclogite of the Saxonian Erzgebirge

    NASA Astrophysics Data System (ADS)

    Žigove?ki Gobac, Željka; Massonne, Hans-Joachim; Theye, Thomas

    2015-04-01

    In the central Saxonian Erzgebirge, ultrahigh pressure rocks occur close to the Saidenbach reservoir. Among these rocks there are eclogites which have experienced metamorphic temperatures in excess of 1000°C (e.g., Massonne, 2013, Elements 9, 267-272). As a result of these high temperatures, the garnet was chemically homogenized with respect to a former growth zonation. Such kind of zonation can be deduced from inclusion minerals such as kyanite, phengite, and (clino)zoisite in garnet cores which point to metamorphic temperatures somewhat below 700°C. In order to test this view of a former prograde zonation in garnet, the content of phosphorus, a presumably much less mobile element at high temperatures compared to the common divalent cations, was determined in this mineral. Concentrations of P in mm-sized garnet in thin sections of eclogite were analyzed by a CAMECA SX100 electron microprobe (EMP). Different instrumental conditions, ranging from beam currents of 50 to 100 nA and counting times of 100 to 600 s on both peak and background at an acceleration voltage of 15 kV, were used in order to find the optimal way to determine this concentration in addition to the concentrations of the common elements at significantly shorter counting times. The interference of the CaK? 2nd order and PK? 1st order peaks was considered by test measurements on standard material. The calculated detection limit for our P measurements was found to be around 13 ppm at the highest beam current and counting time. Several chemical profiles through a more or less concentrically zoned garnet grain were determined by spot analyses. These measurements on a high temperature eclogite from the Saidenbach reservoir yielded relatively low P contents in the core region of garnet of approximately 150 ppm and a significant increase towards the garnet rim. Maximum P contents were found to be around 350 ppm. In the core of garnet small apatite crystals were included whereas in the matrix no phosphate could be detected. Thus, we assume that, in principle, higher P contents could have been introduced in garnet at the highest metamorphic temperatures reached if the P reservoir, apatite, would not have been consumed before. Our study has shown that measurements with the EMP result in a reliable determination of P contents in garnet with relatively low errors. Furthermore, we conclude that phosphorus is a suitable element to at least quantitatively deduce the temperature evolution of garnet. This conclusion with respect to temperature and not to pressure resulted from a literature survey, but further studies are planned to confirm and quantify the temperature dependence of the P introduction in garnet.

  2. Aluminum depletion in komatiites and garnet fractionation in the early Archean mantle: Hafnium isotopic constraints

    SciTech Connect

    Gruau, G. (Max Planck Institut fuer Chemie, Mainz (West Germany) Universite de Rennes (France)); Chauvel, C.; Arndt, N.T. (Max Planck Institut fuer Chemie, Mainz (West Germany)); Cornichet, J. (Universite de Rennes (France))

    1990-11-01

    Hafnium isotopic compositions were measured in Al-depleted and Al-enriched komatiites from the 3,450 Ma old Barberton greenstone belt, southern Africa. All samples have initial {var epsilon}{sub Hf} values close to zero. Such values are at variance with the strongly negative or positive values that should be observed if these rocks came from old garnet-depleted or garnet-enriched layers, such as may have formed during the solidification of an ancient terrestrial magma ocean. The garnet fractionation observed in komatiites probably took place during the melting event.

  3. Exsolution Phenomena of UHP Type in Garnets From Western New England, USA

    NASA Astrophysics Data System (ADS)

    Snoeyenbos, D. R.; Koziol, A. M.

    2008-12-01

    A population of garnet megacrysts, some euhedral and up to 5 cm diameter, from high-grade cover rocks of the Taconian Shelburne Falls arc in western Massachusetts (Karabinos et al. 1998) contains abundant exsolved apatite(OH), rutile, and ilmenite in multiple generations. The host is a restitic kyanite-phlogopite- garnet-rutile-quartz schist with retrograde cordierite or staurolite developed according to bulk Mg# and degree of metamorphic overprint of the matrix. The garnets are significantly Mg-rich (Py25), and retain strong compositional zonation in Mn and Ca (> Sp10, > Gr15 in the cores) consistent with first-cycle metamorphism of a pelitic protolith. The coarsest (up to mm-scale) exsolution is distributed in concentric zones, with apatite(OH) in the garnet cores, a broad mantle containing apatite(OH) + ilmenite and a rim containing apatite(OH) + rutile. Common bilaterally-symmetrical rutile twins and complex multiply-twinned 3-D rutile structures may indicate an anomalous nucleation environment for the coarsest rutile exsolution. The coarse exsolution is difficult to understand as decompressional and instead may have occurred near maximum pressure in accord with mechanisms proposed by Smith (Smith, DC 2006). A pervasive second generation of exsolved submicron apatite(OH) crystals and fine rutile needles and minor euhedral ilmenite plates envelops the coarse phases and extends nearly to the rims. The generally even distribution of this generation of apatite(OH) and the crystallographic orientation of the rutile needles across several cm diameter of euhedral garnet monocrystal requires exsolution from garnet. The garnets retain up to 0.18 wt% P2O5 similar to the highest reported, 0.17 wt% P2O5 from a rutile- and apatite-exsolved UHP crustal garnet from Sulu (Ye et al 2000). With only 0.03 wt% Na2O despite the high P2O5 content, a substitution mechanism other than Na + P must be sought, such as compensatory Mg in VI or vacancy in VIII after Smith (2006). These megacrysts correspond most closely to a well-defined UHP crustal garnet population at Bingara, Australia (Barron et al. 2005) that those authors identify with similar garnets from Sulu and from metapelites from the Greek Rhodope (Mposkos and Kostopoulos, 2001). If exsolution of apatite(OH) from garnet as from Bingara, Sulu, and elsewhere, and from mantle eclogites (Haggerty et al. 1994) is a reliable indicator of UHP metamorphic conditions, then these garnet megacrysts record a previously unrecognized UHP event in the Taconian of western New England.

  4. Interactions of Zircaloy Cladding with Gallium: Final Report

    SciTech Connect

    D.F. Wilson; E.T. Manneschmidt; J.F. King; J.P. Strizak; J.R. DiStefano

    1998-09-01

    The U.S. Department of Energy has established a dual-track approach to the disposition of plutonium arising from the dismantling of nuclear weapons. Both immobilization and reactor-based mixed-oxide (MOX) fuel technologies are being evaluated. The reactor-based MOX fuel option requires assessment of the potential impact of concentrations of gallium (on the order of 1 to 10 ppm), not present in conventional MOX fhel, on cladding material performance. Three previous repmts"3 identified several compatibility issues relating to the presence of gallium in MOX fuel and its possible reaction with fiel cladding. Gallium initially present in weapons-grade (WG) plutonium is largely removed during processing to produce MOX fhel. After blending the plutonium with uranium, only 1 to 10 ppm gallium is expected in the sintered MOX fuel. Gallium present as gallium oxide (G~OJ could be evolved as the suboxide (G~O). Migration of the evolved G~O and diffusion of gallium in the MOX matrix along thermal gradients could lead to locally higher concentrations of G~03. Thus, while an extremely low concentration of gallium in MOX fiel almost ensures a lack of significant interaction of gallium whh Zircaloy fhel cladding, there remains a small probability that corrosion effects will not be negligible. General corrosion in the form of surface alloying resulting from formation of intermetallic compounds between Zircaloy and gallium should be ma& limited and, therefore, superficial because of the expected low ratio of gallium to the surface area or volume of the Zircaloy cladding. Although the expected concentration of gallium is low and there is very limited volubility of gallium in zirconium, especially at temperatures below 700 "C,4 grain boundary penetration and liquid metal embrittlement (LME) are forms of localized corrosion that were also considered. One fuel system darnage mechanism, pellet clad interaction, has led to some failure of the Zircaloy cladding in light-water reactors (LWRS). This has been attributed to stresses in the cladding and one or more aggressive fission products. Stress corrosion cracking by iodines' 6 and LME by cadmium7>8 have been reported, and it is known that Zircaloy can be embrittled by some low-melting metals, (e.g., mercury).g LME is a form of environmentally induced embrittlement that can induce cracking or loss of ductility. LME requties wetting and a tensile stress, but it does not require corrosion penetration. Experimentally, it has been demonstrated that gallium can cause embrittlement of some alloys (e.g., aluminum) at low temperatures,'"' ] ] but experiments relative to LME of zirconium by gallium have been limited and inconclusive.*2 This report describes a series of tests designed to establish the effects of low levels of residual gallium in WG-MOX fhel on its compatibility with Zircaloy. In addition, to establish damage mechanisms it was important to understand types of cladding interactions and available stiety margins with respect to gallium concentration.

  5. High temperature garnet growth in New England: regional temperature-time trends revealed

    NASA Astrophysics Data System (ADS)

    Sullivan, N.; Ostwald, C.; Chu, X.; Baxter, E. F.; Ague, J. J.; Eckert, J. O.

    2013-12-01

    A series of localized ultrahigh-temperature (UHT)/high-temperature (HT) granulite facies regions have been identified within the regional amphibolite facies metamorphic zone of the Central Maine Terrane stretching from north-central New Hampshire, through central Massachusetts, and into northeastern Connecticut. Here, we aim to constrain the age and peak temperature of metamorphism at three localities within this region: Bristol, NH, Phillipston, MA and Willington, CT. Garnet-forming reactions are linked directly to peak metamorphic temperatures through thermodynamic modeling and/or Zr-in-rutile thermometry. Precise garnet geochronology allows us to identify the timing of these peak temperatures, as well as the duration of garnet growth. Geochronologic and thermodynamic work was done on 12 samples collected throughout a ~5 km2 metamorphic 'hotspot' previously identified in Bristol, NH (Chamberlain and Rumble, 1988; Journal of Petrology). The highest temperature assemblage within this hotspot is characterized by the presence of garnet + sillimanite + K-feldspar + cordierite and reached temperatures >820?C. The lowest temperature periphery of the hotspot is characterized by sillimanite + muscovite + K-feldspar + minor garnet and reached a maximum temperature of 650?C. Bulk garnet ages from samples within the hotspot range significantly from at least 400.0 × 2.5 Ma to 352.7 × 1.8 Ma with the youngest ages associated with the lower temperature samples. This collection of ages indicates a prolonged period (~50 Ma) of >650?C temperatures interspersed by period(s) of garnet growth. Zoned garnet geochronology will help reveal whether garnet growth and related heating was continuous or episodic. Further south, in Phillipston, MA, zoned garnet geochronology performed on a 2.5 cm diameter garnet porphyroblast indicates garnet growth spanning 389 - 363 Ma, reaching peak temperatures at the end of that time span of 920-940?C, followed by a younger event recorded in smaller 1-3mm garnet crystals at 351 Ma (which may also reflect resetting of the earlier event), reaching similar temperatures of 920-960?C. These temperatures were obtained by Zr-in-rutile thermometry performed on rutile inclusions within the garnet. Even farther south, in the UHT zone around Willington, CT, temperatures of at least 1000?C were determined using Zr-in-rutile thermometry on rutile inclusions in garnet and reintegration of ternary feldspar compositions (Ague et al., 2013; Geology). The garnet age for a representative UHT sample from this site is 340.3 × 1.7 Ma. The geochronologic data presented here indicates a prolonged period of UHT/HT garnet growth within the Central Maine Terrane, beginning at ~400 Ma in Bristol, NH and ending at ~340 Ma in Willington, CT. Peak temperatures are >820?C in NH, >950?C in MA, and ~1000?C in CT, resulting in a regional pattern of increasing temperature with decreasing age from north to south across this 250 km long region.

  6. Microstructural evidences of garnet plasticity in the continental crust. New example from south Madagascar

    NASA Astrophysics Data System (ADS)

    Malamoud, Karim; Martelat, Jean-Emmanuel; Cordier, Patrick; Schulmann, Karel; Lardeaux, Jean-Marc

    2010-05-01

    Garnet mechanical behaviour is of great importance to understand the rheological evolution of rocks within the mantle and the lower crust. Well-constrained natural examples of plastically deformed garnets are scarce; consequently their identification and the physical parameters controlling their occurrence are still debated. In southern Madagascar, a granulitic metamorphic event has developed during a late Panafrican - Cambrian, east-west shortening (570 Ma). This has led to the development of vertical transpressive shear zones. Within these zones, we identified variations in garnet microstructure following the deformation sequence. In order to understand this evolution, we carried out a thorough microstructural description of samples using the following techniques: optical microscopy and SEM imaging, EBSD technique (localized lattice-preferred orientation), TEM for dislocation density, EMP for chemical analyses, as well as crystal size distribution, statistic grain boundary and shapes analyses (Lexa et al., 2005). The hand samples were quartzites or two-feldspars quartzo- feldsphatic rocks bearing 10 modal percent of garnet. As strain increases, various garnet textures were observed: Type 1) millimetre-sized rounded garnets bearing two types of inclusions, i.e. elongated quartz ribbons and well oriented sillimanite parallel to the lineation; Type 2) elliptic very elongated and lobed garnets (1 to 8 aspect ratio); Type 3) smaller elongated pinch and swell garnets (1 to 3 aspect ratio); and finally Type 4) rounded small garnets (300 microns in diameter). Type 1 textures are due to multiple nucleation garnets and coalescence controlled by aluminous aggregates (biotite and sillimanite). As strain increases, these large skeleton garnets start to re-crystallise preferentially at the tip of lenticular quartz inclusions, giving Type 2 very elongated garnets with unique CPO. The latter then continues to re-crystallise by sub-grain rotation as underlined by the CPO in situ measurements of new re-orientated grains (Type 3). In the type 4, few large garnets remain and only smaller-sized rounded garnets are left. In these highly deformed rocks, fine sillimanite needles are locally preserved and tilted with respect to the main foliation. All garnets from Type 2 to 4 textures are chemically homogeneous. Data from garnets, quartz, and feldspars are compared for each microstructural type and progressive deformation. The observed microstructures are in accordance with garnet ductility coeval with the deformation of quartz K-feldspar and plagioclase and showing mixing of all phases (random distribution) as well as constant grain size (average diameter 200 microns). Our analyses show that under the high-temperature and dry conditions (850°C) all phases are mechanically active. This indicates convergence of strength minerals marked by contrasting (laboratory derived) rheologies. Lexa, O., Štípská, P., Schulmann, K., Baratoux, L., Kröner, A., 2005. Contrasting textural record of two distinct metamorphic events of similar P-T conditions and different durations. Journal of Metamorphic Geology 23. 649-666. http://petrol.natur.cuni.cz/~ondro/polylx:home

  7. Gadolinium-contrast toxicity in patients with kidney disease: nephrotoxicity and nephrogenic systemic fibrosis.

    PubMed

    Perazella, Mark A

    2008-01-01

    Gadolinium is widely employed as a contrast agent for magnetic resonance imaging (MRI) and has generally been considered to be safe. As with iodinated radiocontrast, concern for contrast-induced nephropathy existed with gadolinium-contrast as it possessed many similar qualities (hyperosmolar, renal excretion via glomerular filtration). Early studies in low risk patients suggested a benign renal profile, however, recent studies raise the possibility of nephrotoxicity. In addition, reports of a previously rare condition entitled nephrogenic systemic fibrosis (NSF) have recently emerged in patients with advanced kidney disease and have been linked to exposure to gadolinium-contrast. Nephrogenic systemic fibrosis is a debilitating disorder in which progressive and severe fibrosis of the skin and other systemic organs that leads to significant disability and is associated with increased mortality. Initially reported most commonly in end stage renal disease (ESRD) patients receiving dialysis, it is also described in patients with severe acute kidney injury (AKI) and advanced chronic kidney disease (stages 4 and 5) not requiring dialysis. In addition to underlying kidney disease, the risk of developing NSF is increased with larger doses of gadolinium (or multiple exposures), exposure to specific gadolinium chelates (non-ionic, linear), underlying pro-inflammatory states (in particular vascular endothelial dysfunction), and perhaps some currently unrecognized cofactors. No clearly effective therapies exist for NSF, although recovery from AKI and establishment of normal kidney function with renal transplantation appear to reverse or stabilize the disease in some cases. Avoidance of gadolinium exposure appears to be the best approach for patients who maintain risk factors. When gadolinium exposure occurs, aggressive hemodialysis following exposure may be useful as gadolinium is efficiently removed by this extracorporeal technique. Peritoneal dialysis clearance of gadolinium is poor, but aggressive peritoneal dialysis prescriptions have not been studied for gadolinium removal. PMID:18690983

  8. High-Pressure Phase Transition in Yttrium Iron Garnet

    NASA Astrophysics Data System (ADS)

    Stan, C. V.; Wang, J.; Zouboulis, I. S.; Prakapenka, V.; Duffy, T. S.

    2014-12-01

    High-pressure investigations of rare earth transition metal oxide garnets have revealed structural and magnetic phase transitions, including pressure-induced amorphization, magnetic collapse, spin crossover transitions and metallization, as well as transformation to highly-incompressible oxides. Yttrium iron garnet (YIG), Y3Fe5O12, exhibits interesting magnetic properties, behaving as a ferrimagnet with a Néel temperature TN ~ 559 K at ambient pressure and transforming to a paramagnetic material at high temperatures. At high temperatures and pressures, it converts to a GdFeO3-type perovskite structure. However, the composition of the perovskite is debated, with two proposed reaction pathways, leading to either (Y0.75Fe0.25)FeO3-perovskite or a mixture of YFeO3-perovskite and Fe2O3. Here, we synthesized YIG-perovskite in the diamond anvil cell above 18 GPa and 1500 K at GeoSoilEnviroCARS beamline 13-ID-D of the Advanced Photon Source. NaCl was used as a quasihydrostatic pressure medium, and Au, with the Fei equation of state, was used as the pressure calibrant and laser absorber. Our measurements of the perovskite structure extend to 70 GPa with annealing at each pressure step. We do not find any iron oxide diffraction peaks after heating, indicating that the perovskite structure is likely (Y0.75Fe0.25)FeO3. We observe a previously unknown ~5% volume discontinuity in the perovskite between 44 and 50 GPa. This discontinuity is not accompanied by a change in the diffraction pattern, suggesting that the Fe in this structure undergoes a high-spin to low-spin transition. When compressing without laser heating, we confirm the amorphization of YIG starting material at 50 GPa that was previously observed by Gavriliuk et al. (2006). This amorphous material is easily converted to the low-spin perovskite upon heating above 1400 K.

  9. Effect of oxidation on the Mechanical Properties of Liquid Gallium and Eutectic Gallium-Indium

    E-print Network

    Xu, Qin; Guo, Qiti; Jaeger, Heinrich; Brown, Eric

    2012-01-01

    Liquid metals exhibit remarkable mechanical properties, in particular large surface tension and low viscosity. However, these properties are greatly affected by oxidation when exposed to air. We measure the viscosity, surface tension, and contact angle of gallium (Ga) and a eutectic gallium-indium alloy (eGaIn) while controlling such oxidation by surrounding the metal with an acid bath of variable concentration. Rheometry measurements reveal a yield stress directly attributable to an oxide skin that obscures the intrinsic behavior of the liquid metals. We demonstrate how the intrinsic viscosity can be obtained with precision through a scaling technique that collapses low- and high-Reynolds number data. Measuring surface tension with a pendant drop method, we show that the oxide skin generates a surface stress that mimics surface tension and develop a simple model to relate this to the yield stress obtained from rheometry. We find that yield stress, surface tension, and contact angle all transition from solid-...

  10. Preliminary Experimental Measurements for a Gallium Electromagnetic (GEM) Thruster

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Burton, Rodney L.; Glumac, Nick G.; Polzin, Kurt A.

    2007-01-01

    A low-energy gallium plasma source is used to perform a spatially and temporally broad spectroscopic survey in the 220-520 nm range. Neutral, singly, and doubly ionized gallium are present in a 20 J, 1.8 kA (peak) arc discharge operating with a central cathode. When the polarity of the inner electrode is reversed the discharge current and arc voltage waveforms remain similar. Utilizing a central anode configuration, multiple Ga lines are absent in the 270-340 nm range. In addition, neutral and singly ionized Fe spectral lines are present, indicating erosion of the outer electrode. With graphite present on the insulator to facilitate breakdown, line emission from the gallium species is further reduced and while emissions from singly and doubly ionized carbon atoms and molecular carbon (C2) radicals are observed. These data indicate that a significant fraction of energy is shifted from the gallium and deposited into the various carbon species.

  11. Raman spectra of solid, molten, and gaseous gallium trichloride

    Microsoft Academic Search

    A. B. Salyulev; I. D. Zakiryanova

    2010-01-01

    The structure of crystalline, molten (from the melting to the critical temperature), and gaseous (at high vapor pressures)\\u000a gallium trichloride is studied by Raman spectroscopy for the first time.

  12. Reversible expansion of gallium-stabilized (delta)-plutonium

    SciTech Connect

    Wolfer, W G; Oudot, B; Baclet, N

    2006-02-27

    It is shown that the transient expansion of plutonium-gallium alloys observed both in the lattice parameter as well as in the dimension of a sample held at ambient temperature can be explained by assuming incipient precipitation of Pu{sub 3}Ga. However, this ordered {zeta}-phase is also subject to radiation-induced disordering. As a result, the gallium-stabilized {delta}-phase, being metastable at ambient temperature, is driven towards thermodynamic equilibrium by radiation-enhanced diffusion of gallium and at the same time reverted back to its metastable state by radiation-induced disordering. A steady state is reached in which only a modest fraction of the gallium present is arranged in ordered {zeta}-phase regions.

  13. Gallium-67 uptake in the lung associated with metastatic calcification

    SciTech Connect

    Auerbach, J.M.; Ho, J.

    1981-03-01

    The case of a patient in whom pulmonary calcification appeared rapidly, accompanied by diffuse gallium-67 uptake in the lungs is reported. This finding, associated with metastatic calcification in the absence of inflammation or neoplasm, has not been previously reported.

  14. Mitochondrial dysfunction induced by different concentrations of gadolinium ion.

    PubMed

    Zhao, Jie; Zhou, Zhi-Qiang; Jin, Jian-Cheng; Yuan, Lian; He, Huan; Jiang, Feng-Lei; Yang, Xiao-Gang; Dai, Jie; Liu, Yi

    2014-04-01

    Gadolinium-based compounds are the most widely used paramagnetic contrast agents in magnetic resonance imaging on the world. But the tricationic gadolinium ion (Gd(3+)) could induce cell apoptosis probably because of its effects on mitochondria. Until now, the mechanism about how Gd(3+) interacts with mitochondria is not well elucidated. In this work, mitochondrial swelling, collapsed transmembrane potential and decreased membrane fluidity were observed to be important factors for mitochondrial permeability transition pore (mtPTP) opening induced by Gd(3+). The protection effect of CsA (Cyclosporin A) could confirm high concentration of Gd(3+) (500 ?M) would trigger mtPTP opening. Moreover, mitochondrial outer membrane breakdown and volume expansion observed clearly by transmission electron microscopy and the release of Cyt c (Cytochrome c) could explain the mtPTP opening from another aspect. In addition, MBM(+) (monobromobimane(+)) and DTT (dithiothreitol) could protect thiol (-SH) groups from oxidation so that the toxicity of Gd(3+) might be resulted from the chelation of -SH of membrane proteins by free Gd(3+). Gd(3+) could inhibit the initiation of mitochondrial membrane lipid peroxidation, so it might interact with anionic lipids too. These findings will highly contribute to the safe applications of Gd-based agents. PMID:24321333

  15. Hepatobiliary MR Imaging with Gadolinium Based Contrast Agents

    PubMed Central

    Frydrychowicz, Alex; Lubner, Meghan G.; Brown, Jeffrey J.; Merkle, Elmar M.; Nagle, Scott K.; Rofsky, Neil M.; Reeder, Scott B.

    2011-01-01

    The advent of gadolinium-based “hepatobiliary” contrast agents offers new opportunities for diagnostic MRI and has triggered a great interest for innovative imaging approaches to the liver and bile ducts. In this review article we will discuss the imaging properties of the two gadolinium-based hepatobiliary contrast agents currently available in the USA, gadobenate dimeglumine and gadoxetic acid, as well as important pharmacokinetic differences that affect their diagnostic performance. We will review potential applications, protocol optimization strategies, as well as diagnostic pitfalls. A variety of illustrative case examples will be used to demonstrate the role of these agents in detection and characterization of liver lesions as well as for imaging the biliary system. Changes in MR protocols geared towards optimizing workflow and imaging quality will also be discussed. It is our aim that the information provided in this article will facilitate the optimal utilization of these agents, and will stimulate the reader‘s pursuit of new applications for future benefit. PMID:22334493

  16. Gadolinium dose enhancement studies in microbeam radiation therapy.

    PubMed

    Prezado, Y; Fois, G; Le Duc, G; Bravin, A

    2009-08-01

    Microbeam radiation therapy (MRT) is an innovative technique to treat brain tumors. The synchrotron generated x-ray beam, used for the treatment, is collimated and delivered in an array of narrow micrometer-sized planar rectangular fields. Several preclinical experiments performed at the Brookhaven National Laboratory (BNL) and at the European Synchrotron Radiation Facility (ESRF) have shown the sparing effect of the healthy tissue and the ablation of tumors in several animal models. It has also been determined that MRT yields a higher therapeutic index than nonsegmented beams of the same energy. This therapeutic index could be greatly improved by loading the tumor with high atomic number (Z) contrast agents. In this work, the dose enhancement factors and the peak to valley dose ratios (PVDRs) are assessed for different gadolinium (Z = 64) concentrations in the tumor and different microbeam energies by using Monte Carlo simulations (PENELOPE 2006 code). A significant decrease in the PVDR values in the tumor, and therefore a relevant increase in the dose deposition, is found in the presence of gadolinium. The optimum energy for the dose deposition in the tumor while keeping a high PVDR in the healthy tissues, which guaranties their sparing, has been investigated. PMID:19746791

  17. Compatibility of ITER candidate materials with static gallium

    Microsoft Academic Search

    P. R. Luebbers; O. K. Chopra

    1995-01-01

    Corrosion tests have been conducted to determine the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor (ITER) first wall\\/blanket systems, e.g., Type 316 stainless steel (SS), Inconel 625, and Nb-5 Mo-1 Zr. The results indicate that Type 316 SS is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant.

  18. Compatibility of ITER candidate structural materials with static gallium

    Microsoft Academic Search

    P. R. Luebbers; W. F. Michaud; O. K. Chopra

    1993-01-01

    Tests were conducted on the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor, e.g., Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy, as well as Armco iron, Nickel 270, and pure chromium. Type 316 stainless steel is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At

  19. Lithium isotope effect accompanying electrochemical insertion of lithium into gallium

    Microsoft Academic Search

    Keita Zenzai; Satoshi Yanase; Yong-Hong Zhang; Takao Oi

    2008-01-01

    Lithium has been electrochemically inserted from a 1:2 (v\\/v) mixed solution of ethylene carbonate (EC) and methylethyl carbonate (MEC) containing 1M LiClO4 or from dimethyl sulfoxide (DMSO) containing 1M LiCl into gallium, and the lithium isotope fractionation accompanying the insertion has been observed. The lighter isotope was preferentially fractionated into gallium, which was in accordance with the theory of the

  20. Interactions of Zircaloy cladding with gallium: 1998 midyear status

    Microsoft Academic Search

    D. F. Wilson; J. R. DiStefano; J. P. Strizak; J. F. King; E. T. Manneschmidt

    1998-01-01

    A program has been implemented to evaluate the effect of gallium in mixed-oxide (MOX) fuel derived from weapons-grade (WG) plutonium on Zircaloy cladding performance. The objective is to demonstrate that low levels of gallium will not compromise the performance of the MOX fuel system in a light-water reactor. The graded, four-phase experimental program was designed to evaluate the performance of

  1. Magnetostriction and Magnetic Heterogeneities in Iron-Gallium

    Microsoft Academic Search

    M. Laver; C. Mudivarthi; J. R. Cullen; A. B. Flatau; W.-C. Chen; S. M. Watson; M. Wuttig

    2010-01-01

    Iron-gallium alloys Fe1-xGax exhibit an exceptional increase in magnetostriction with gallium content. We present small-angle neutron scattering investigations on a Fe0.81Ga0.19 single crystal. We uncover heterogeneities with an average spacing of 15 nm and with magnetizations distinct from the matrix. The moments in and around the heterogeneities are observed to reorient with an applied magnetic field or mechanical strain. We

  2. Magnetostriction and Magnetic Heterogeneities in Iron-Gallium

    Microsoft Academic Search

    M. Laver; C. Mudivarthi; J. R. Cullen; M. Wuttig; A. B. Flatau; W.-C. Chen; S. M. Watson

    2010-01-01

    Iron-gallium alloys Fe{sub 1-x}Gaâ exhibit an exceptional increase in magnetostriction with gallium content. We present small-angle neutron scattering investigations on a Fe{sub 0.81}Ga{sub 0.19} single crystal. We uncover heterogeneities with an average spacing of 15 nm and with magnetizations distinct from the matrix. The moments in and around the heterogeneities are observed to reorient with an applied magnetic field or

  3. Intrinsic Pinning of a Ferromagnetic Domain Wall in Yttrium Iron Garnet Films with Strong Uniaxial Anisotropy

    Microsoft Academic Search

    K. S. Novoselov; S. V. Dubonos; S. V. Morozov; E. W. Hill; I. V. Grigorieva; A. K. Geim

    2005-01-01

    No Heading Movements of individual domain walls in a ferromagnetic garnet were studied with angstrom resolution. The measurements reveal that domain walls can be locked between adjacent crystallographic planes and propagate by distinct steps matching the lattice periodicity.

  4. Garnet-bearing ultramafic rocks from the Dominican Republic: Fossil mantle plume fragments in an ultra high pressure oceanic complex?

    NASA Astrophysics Data System (ADS)

    Gazel, Esteban; Abbott, Richard N.; Draper, Grenville

    2011-07-01

    Ultra high pressure (UHP) garnet-bearing ultramafic rocks from the Dominican Republic may represent the only known example where such rocks were exhumed at an ocean-ocean convergent plate boundary, and where the protolith crystallized from a UHP magma (> 3.2 GPa, > 1500 °C). This study focuses on the petrology and geochemistry of one of the ultramafic lithologies, the pegmatitic garnet-clinopyroxenite (garnet + clinopyroxene + spinel + corundum + hornblende). Three distinct types of garnet were recognized: Type-1 garnet (low Ca, high Mg) is interpreted as near magmatic (P > 3.2 GPa, > 1500 °C). Type-1? garnet (high Ca, low Mg) is interpreted as having formed approximately isochemically from magmatic high-Al clinopyroxene. Type-2 garnet (intermediate Ca, high Mg, and low Fe + Mn) formed together with hornblende as a result of late, low-pressure retrograde hydration. Clinopyroxene is close to diopside-hedenbergite (Mg# ~ 88) and metasomatized by arc-related fluids. Spinel and corundum occur as microinclusions in type-1 and type-1? garnets in the only reported natural occurrence of coexisting garnet + spinel + corundum, indicative of very high pressure. Chondrite-normalized REEs (rare earth elements) of the garnets show humped or weakly sinusoidal patterns, typically associated with garnet inclusions in diamond and garnet in kimberlite that crystallized at UHP conditions. These humped to weakly sinusoidal REE patterns developed as the result of interaction with a light REE-enriched metasomatic fluid. Partitioning of REEs between type-1? and type-1 garnets is consistent with the former having inherited its REEs from a high-Al clinopyroxene predecessor. The partitioning preserves a record of near-solidus temperatures (~ 1475 °C). Petrology and phase relationships independently suggest near-solidus conditions > 1500 °C (the highest temperature conditions reported in a UHP orogenic setting), providing evidence for an origin in a mantle plume. Therefore, the Dominican ultramafic rocks may represent the only example of exhumed “fossil fragments” of mantle plume in an orogenic setting (oceanic or continental).

  5. Characterisation of bismuth-doped yttrium iron garnet layers prepared by sol–gel process

    Microsoft Academic Search

    J.-L Rehspringer; J. Bursik; D. Niznansky; A. Klarikova

    2000-01-01

    Yttrium iron garnets and Bi-substituted yttrium iron garnets were prepared by two different sol–gel processes. We investigated the evolution with temperature of XRD patterns and of the magnetisation of powders issued from sol–gel solution decomposition. We prepared layers on silica glass by the spin- or dip-coating processes. XRD patterns on layers were also obtained. The dependency of the Faraday effect

  6. Integration of magneto-optical active bismuth iron garnet on nongarnet substrates

    Microsoft Academic Search

    Timo Körner; Andreas Heinrich; Martin Weckerle; Patrick Roocks; Bernd Stritzker

    2008-01-01

    For optical communication, high quality magneto-optical active iron garnet films such as Y3Fe5O12 are important ceramic systems with extensive applications, e.g., as optical isolators [H. Dötsch et al., J. Opt. Soc. Am. B 22, 240 (2005)], optical modulators, etc. Thereby, garnets stand out due to their high Faraday rotation and low optical losses in the near infrared. Currently, it is

  7. Aluminum depletion in komatiites and garnet fractionation in the early Archean mantle - Hafnium isotopic constraints

    Microsoft Academic Search

    G. Gruau; C. Chauvel; N. T. Arndt; J. Cornichet

    1990-01-01

    Hafnium isotopic compositions were measured in Al-depleted and Al-enriched komatiites from the 3450-Ma-old Barberton greenstone belt, southern Afric. All samples have initial epsilon (Hf) values close to zero. Such values are at variance with the strongly negative or positive values that should be observed if these rocks came from old garnet-depleted or garnet-enriched layers, such as may have formed during

  8. Oxygen Isotope Composition of Eclogitic and Peridotitic Garnet Xenocrysts from the La Ceniza Kimberlite, Guaniamo, Venezuela

    Microsoft Academic Search

    Daniel J. Schulze; John W. Valley; Michael J. Spicuzza; Dominic M. De R. Channer

    2003-01-01

    Although diamonds from kimberlites in the Guaniamo region of Venezuela overwhelmingly belong to the eclogite suite, the mantle xenocryst suite is dominated by peridotitic garnets, with a significant harzburgite component. In the 0.5 to 1.0 mm size fraction of heavy mineral concentrate from the La Ceniza kimberlite, approximately 23% of the garnet xenocrysts are classified as G10 (harzburgitic), 75% are

  9. Garnet Lu–Hf dating of retrograde fluid activity during ultrahigh-pressure metamorphic eclogites exhumation

    Microsoft Academic Search

    Hao Cheng; Eizo Nakamura; Zuyi Zhou

    2009-01-01

    Previous studies on the atoll-shaped garnets in ultrahigh-pressure (UHP) metamorphic eclogites from the Dabie orogen, east-central\\u000a China, suggest a fluid-enhanced overgrowth origin at the onset of exhumation. The atoll-garnets bearing eclogite place better\\u000a constraints on the timing of the retrograde fluid activity and are a straightforward target to gain insight into the isotopic\\u000a equilibrium and\\/or disequilibrium during exhumation. Comprehensive textural,

  10. Pressure Dependence of the Microwave Resonance Properties of Some Spinel and Garnet Ferrites

    Microsoft Academic Search

    I. P. Kaminow; R. V. Jones

    1961-01-01

    The anisotropy field, g value, and linewidth of several spinel and garnet ferrites have been measured at X band and room temperature as functions of hydrostatic pressure to 104 kg\\/cm2. The crystals studied include yttrium, ytterbium, and erbium iron garnet; magnesium ferrite (with different distributions of Mg2+ ions on A and B sites); and Ni1-zCozFe2O4 with z=0, 0.05 and 0.10.

  11. Elasticity of Some Mantle Crystal Structures 3. Spessartite-Almandine Garnet

    Microsoft Academic Search

    Herbert Wang; Gene Simmons

    1974-01-01

    The single-crystal elastic constants and their pressure derivatives for a spessartite-almandine garnet ((Mn, Fe)A12SiO2) have been determined at room temperature by the pulse echo overlap method. The elastic constants at P = 1 bar are Cn = 3.085 Mbar, C2 = 1.123 Mbar, and C44 = 0.948 Mbar, within 3% of previous measurements on Mn-Fe and Mg-Fe garnets. The pressure

  12. Cathodoluminescence spectra of gallium nitride nanorods

    PubMed Central

    2011-01-01

    Gallium nitride [GaN] nanorods grown on a Si(111) substrate at 720°C via plasma-assisted molecular beam epitaxy were studied by field-emission electron microscopy and cathodoluminescence [CL]. The surface topography and optical properties of the GaN nanorod cluster and single GaN nanorod were measured and discussed. The defect-related CL spectra of GaN nanorods and their dependence on temperature were investigated. The CL spectra along the length of the individual GaN nanorod were also studied. The results reveal that the 3.2-eV peak comes from the structural defect at the interface between the GaN nanorod and Si substrate. The surface state emission of the single GaN nanorod is stronger as the diameter of the GaN nanorod becomes smaller due to an increased surface-to-volume ratio. PMID:22168896

  13. Direct Band Gap Wurtzite Gallium Phosphide Nanowires

    PubMed Central

    2013-01-01

    The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555–690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

  14. Gallium arsenide solar array subsystem study

    NASA Technical Reports Server (NTRS)

    Miller, F. Q.

    1982-01-01

    The effects on life cycle costs of a number of technology areas are examined for a gallium arsenide space solar array. Four specific configurations were addressed: (1) a 250 KWe LEO mission - planer array; (2) a 250 KWe LEO mission - with concentration; (3) a 50 KWe GEO mission planer array; (4) a 50 KWe GEO mission - with concentration. For each configuration, a baseline system conceptual design was developed and the life cycle costs estimated in detail. The baseline system requirements and design technologies were then varied and their relationships to life cycle costs quantified. For example, the thermal characteristics of the baseline design are determined by the array materials and masses. The thermal characteristics in turn determine configuration, performance, and hence life cycle costs.

  15. Direct band gap wurtzite gallium phosphide nanowires.

    PubMed

    Assali, S; Zardo, I; Plissard, S; Kriegner, D; Verheijen, M A; Bauer, G; Meijerink, A; Belabbes, A; Bechstedt, F; Haverkort, J E M; Bakkers, E P A M

    2013-04-10

    The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555-690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

  16. Radiation damage of gallium arsenide production cells

    NASA Technical Reports Server (NTRS)

    Mardesich, N.; Garlick, G. F. J.

    1987-01-01

    High-efficiency gallium arsenide cells, made by the liquid epitaxy method (LPE), have been irradiated with 1-MeV electrons up to fluences of 10 to the 16th e/sq cm. Measurements have been made of cell spectral response and dark and light-excited current-voltage characteristics and analyzed using computer-based models to determine underlying parameters such as damage coefficients. It is possible to use spectral response to sort out damage effects in the different cell component layers. Damage coefficients are similar to other reported in the literature for the emitter and buffer (base). However, there is also a damage effect in the window layer and possibly at the window emitter interface similar to that found for proton-irradiated liquid-phase epitaxy-grown cells. Depletion layer recombination is found to be less than theoretically expected at high fluence.

  17. Gallium Arsenide solar cell radiation damage experiment

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Kinnison, J. D.; Herbert, G. A.; Meulenberg, A.

    1991-01-01

    Gallium arsenide (GaAs) solar cells for space applications from three different manufactures were irradiated with 10 MeV protons or 1 MeV electrons. The electrical performance of the cells was measured at several fluence levels and compared. Silicon cells were included for reference and comparison. All the GaAs cell types performed similarly throughout the testing and showed a 36 to 56 percent power areal density advantage over the silicon cells. Thinner (8-mil versus 12-mil) GaAs cells provide a significant weight reduction. The use of germanium (Ge) substrates to improve mechanical integrity can be implemented with little impact on end of life performance in a radiation environment.

  18. Growth Control in Colon Epithelial Cells: Gadolinium Enhances Calcium-Mediated Growth Regulation

    PubMed Central

    Attili, Durga; Jenkins, Brian; Aslam, Muhammad Nadeem; Dame, Michael K.

    2013-01-01

    Gadolinium, a member of the lanthanoid family of transition metals, interacts with calcium-binding sites on proteins and other biological molecules. The overall goal of the present investigation was to determine if gadolinium could enhance calcium-induced epithelial cell growth inhibition in the colon. Gadolinium at concentrations as low as 1–5 µM combined with calcium inhibits proliferation of human colonic epithelial cells more effectively than calcium alone. Gadolinium had no detectable effect on calcium-induced differentiation in the same cells based on change in cell morphology, induction of E-cadherin synthesis, and translocation of E-cadherin from the cytosol to the cell surface. When the colon epithelial cells were treated with gadolinium and then exposed to increased calcium concentrations, movement of extracellular calcium into the cell was suppressed. In contrast, gadolinium treatment had no effect on ionomycin-induced release of stored intracellular calcium into the cytoplasm. Whether these in vitro observations can be translated into an approach for reducing abnormal proliferation in the colonic mucosa (including polyp formation) is not known. These results do, however, provide an explanation for our recent findings that a multi-mineral supplement containing all of the naturally occurring lanthanoid metals including gadolinium are more effective than calcium alone in preventing colon polyp formation in mice on a high-fat diet. PMID:23008064

  19. Growth control in colon epithelial cells: gadolinium enhances calcium-mediated growth regulation.

    PubMed

    Attili, Durga; Jenkins, Brian; Aslam, Muhammad Nadeem; Dame, Michael K; Varani, James

    2012-12-01

    Gadolinium, a member of the lanthanoid family of transition metals, interacts with calcium-binding sites on proteins and other biological molecules. The overall goal of the present investigation was to determine if gadolinium could enhance calcium-induced epithelial cell growth inhibition in the colon. Gadolinium at concentrations as low as 1-5 ?M combined with calcium inhibits proliferation of human colonic epithelial cells more effectively than calcium alone. Gadolinium had no detectable effect on calcium-induced differentiation in the same cells based on change in cell morphology, induction of E-cadherin synthesis, and translocation of E-cadherin from the cytosol to the cell surface. When the colon epithelial cells were treated with gadolinium and then exposed to increased calcium concentrations, movement of extracellular calcium into the cell was suppressed. In contrast, gadolinium treatment had no effect on ionomycin-induced release of stored intracellular calcium into the cytoplasm. Whether these in vitro observations can be translated into an approach for reducing abnormal proliferation in the colonic mucosa (including polyp formation) is not known. These results do, however, provide an explanation for our recent findings that a multi-mineral supplement containing all of the naturally occurring lanthanoid metals including gadolinium are more effective than calcium alone in preventing colon polyp formation in mice on a high-fat diet. PMID:23008064

  20. Amorphization of rare earth aluminate garnets under ion irradiation and decay of ²??Cm admixture

    SciTech Connect

    Livshits, T. S. [Russian Academy of Sciences (RAS), Moscow (Russian Federation).; Lizin, A. A. [Joint Stock Co., State Scientific Center – Research Inst. of Atomic Reactors (JSC SSC-RIAR), Dimitrovgrad (Russian Federation); Zhang, J. M. [Univ. of Michigan, Ann Arbor, MI (United States); Ewing, R. C. [Univ. of Michigan, Ann Arbor, MI (United States)

    2010-08-01

    The stability of synthetic REE-aluminate garnets irradiated by accelerated Kr2+ ions and affected by alpha decay of ²??Cm (T1/2 = 18.1 yr) has been studied. The dose of irradiation sufficient for the complete disordering of the aluminate garnet structure is 0.40–0.55 displacements per atom. This value increases with rising temperature due to the increasing intensity of recovery from radiation damage to the lattice by heating. The critical temperature above which the structure of REE-aluminate is not damaged by radiation is 550°C. The amorphization dose for aluminates with garnet structure is two to three times higher than of that previously studied ferrites; the critical temperature of both is similar. In resistance to radiation, aluminate garnets do not yield to zirconolite and exceed titanate pyrochlore. Heating to 250°C does not lead to substantial recovery from radiation defects in the garnet structure. The radiation impact on matrices of real actinide (An) wastes is lower than that related to ion irradiation and ²??Cm doping, and this facilitates a higher radiation resistance of garnets containing HLW.

  1. The origin of garnet in the anorthosite-charnockite suite of the Adirondacks

    USGS Publications Warehouse

    McLelland, J.M.; Whitney, P.R.

    1977-01-01

    Detailed analysis of textural and chemical criteria in rocks of the anorthosite-charnockite suite of the Adirondack Highlands suggests that development of garnet in silica-saturated rocks of the suite occurs according to the reaction: {Mathematical expression}, where ?? is a function of the distribution of Fe and Mg between the several coexisting ferromagnesian phases. Depending upon the relative amounts of Fe and Mg present, quartz may be either a reactant or a product. Using an aluminum-fixed reference frame, this reaction can be restated in terms of a set of balanced partial reactions describing the processes occurring in spatially separated domains within the rock. The fact that garnet invariably replaces plagioclase as opposed to the other reactant phases indicates that the aluminum-fixed model is valid as a first approximation. This reaction is univariant and produces unzoned garnet. It differs from a similar equation proposed by de Waard (1965) for the origin of garnet in Adirondack metabasic rocks, i.e. 6 Orthopyroxene+2 Anorthite = Clinopyroxene+Garnet+2 Quartz, the principle difference being that iron oxides (ilmenite and/or magnetite) are essential reactant phases in the present reactions. The product assemblage (garnet+clinopyroxene+plagioclase ?? orthopyroxene ?? quartz) is characteristic of the clinopyroxene-almandine subfacies of the granulite facies. ?? 1977 Springer-Verlag.

  2. Relative Strength of the Pyrope–majorite Solid Solution and the Flow-law of Majorite Containing Garnets

    SciTech Connect

    Hunt, S.; Dobson, D; Li, L; Weidner, D; Brodholt, J

    2010-01-01

    Even though the garnet phase is the second most abundant phase in the upper-mantle and transition-zone, no previous studies have directly measured the effect of majorite content on the strength of garnet under mantle conditions. Here we report the results of constant strain-rate and stress-relaxation experiments on garnets in the pyrope-majorite solid solution which constrain the strength of majoritic containing garnets relative to pyrope as a function of majorite content and temperature. We find that at temperatures below 650 C both pure pyrope and majoritic garnets have the same strength. Conversely, above 650 C we find that majoritic garnets are initially stronger than pure pyrope but weaken with increasing temperature and majorite content and with significant majorite contents are weaker than pyrope above approximately 800 C. We develop a flow law for the entire pyrope-majorite solid solution as a function of temperature and majorite content.

  3. Distinctive Signature of Indium Gallium Nitride Quantum Dot Lasing in Microdisk Cavities

    E-print Network

    Woolf, Alexander; Puchtler, Tim; Aharonovich, Igor; Zhu, Tong Tong; Niu, Nan; Wang, Danqing; Oliver, Rachel A.; Hu, Evelyn L.

    2014-01-01

    Low threshold lasers realized within compact, high quality optical cavities enable a variety of nanophotonics applications. Gallium nitride (GaN) materials containing indium gallium nitride (InGaN) quantum dots and quantum wells offer an outstanding...

  4. Retention of Sm–Nd isotopic ages in garnets subjected to high-grade thermal reworking: implications for diffusion rates of major and rare earth elements and the Sm–Nd closure temperature in garnet

    Microsoft Academic Search

    Rian Dutch; Martin Hand

    2010-01-01

    Garnet is a vital mineral for determining constrained P–T–t paths as it can give both the P–T and t information directly. However, estimates of the closure temperature of the Sm–Nd system in garnet vary considerably leading\\u000a to significant uncertainties in the timing of peak conditions. In this study, five igneous garnets from an early Proterozoic\\u000a 2414 ± 6 Ma garnet—cordierite bearing s-type granite—which

  5. Bonding mechanism of a yttrium iron garnet film on Si without the use of an intermediate layer

    NASA Astrophysics Data System (ADS)

    Pantzas, Konstantinos; Patriarche, Gilles; Talneau, Anne; Youssef, Jamal Ben

    2014-10-01

    Direct bonding of yttrium iron garnet (YIG) on silicon without the use of an intermediate bonding layer is demonstrated and characterized using scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy. During the bonding experiment, the garnet is reduced in the presence of oxide-free silicon. As a result, a 5 nm thick SiO2/amorphous-YIG bilayer is formed and welds the garnet to silicon.

  6. Bonding mechanism of a yttrium iron garnet film on Si without the use of an intermediate layer

    SciTech Connect

    Pantzas, Konstantinos, E-mail: konstantinos.pantzas@lpn.cnrs.fr [CNRS-LPN, Route de Nozay, F-91460 Marcoussis (France); Institut P', CNRS-Université de Poitiers - ENSMA - UPR 3346, SP2MI - Téléport 2 Bd Marie Pierre Curie, B.P. 30179, F-86962, Futuroscope Chasseneuil Cedex (France); Patriarche, Gilles; Talneau, Anne [CNRS-LPN, Route de Nozay, F-91460 Marcoussis (France); Youssef, Jamal Ben [Laboratoire de Magnetisme de Bretagne, 6 avenue Le Gorgeu, 29238 Brest Cedex 3 (France)

    2014-10-06

    Direct bonding of yttrium iron garnet (YIG) on silicon without the use of an intermediate bonding layer is demonstrated and characterized using scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy. During the bonding experiment, the garnet is reduced in the presence of oxide-free silicon. As a result, a 5?nm thick SiO{sub 2}/amorphous-YIG bilayer is formed and welds the garnet to silicon.

  7. Kondo Physics in 4 f metals: Gadolinium nanocontacts

    NASA Astrophysics Data System (ADS)

    Olivera, Bernat; Untiedt, Carlos; Scheer, Elke

    2015-03-01

    The study of electron transport in conducting materials at the nanoscale can be carried out by using Scanning Tunneling Microscope (STM) and Mechanically Controllable Break Junction techniques (MCBJ). At such scales, Kondo effect vanishes the magnetic properties of the 3 d transition metals Fe, Co and Ni. The 4 f rare earth metals are an interesting aim of study because of their strong magnetic properties among other things. At our laboratories we have measured gadolinium with both STM and MCBJ techniques. In the spectroscopy measurements of this material we perceive a set of features that could be related to its magnetic properties. The interplay between the 4f7 and 5d1 orbitals from Gd drives us to pose the mechanisms that are involved in the electronic transport properties of these systems.

  8. SWI enhances vein detection using gadolinium in multiple sclerosis.

    PubMed

    Maggi, Pietro; Mazzoni, Lorenzo N; Moretti, Marco; Grammatico, Matteo; Chiti, Stefano; Massacesi, Luca

    2015-03-01

    Susceptibility weighted imaging (SWI) combined with the FLAIR sequence provides the ability to depict in vivo the perivenous location of inflammatory demyelinating lesions - one of the most specific pathologic features of multiple sclerosis (MS). In addition, in MS white matter (WM) lesions, gadolinium-based contrast media (CM) can increase vein signal loss on SWI. This report focuses on two cases of WM inflammatory lesions enhancing on SWI images after CM injection. In these lesions in fact the CM increased the contrast between the parenchyma and the central vein allowing as well, in one of the two cases, the detection of a vein not visible on the same SWI sequence acquired before CM injection. PMID:25815209

  9. Luminescence and photosensitivity of gadolinium labeled hematoporphyrin monomethyl ether.

    PubMed

    Wang, Peng; Qin, Feng; Wang, Li; Li, Fajun; Zheng, Yangdong; Song, Yunfei; Zhang, Zhiguo; Cao, Wenwu

    2014-02-10

    Photodynamic therapy for deep-lying lesions needs an appropriate imaging modality, precise evaluation of tissue oxygen and an effective photosensitizer. Gadolinium based metalloporphyrins Gd(III)-HMME is proposed in this study as a potential multifunctional theranostic agent, as photosensitizer, ratiometric oxygen sensor and MRI contrast agent. The time resolved spectroscopy revealed the luminescence peak of Gd(III)-HMME at 710 and 779 nm with a lifetime of 64 ?s in oxygen-free methanol to be phosphorescent. This phosphorescence is strongly dependent on dissolved oxygen concentration. Its intensity in oxygen saturated methanol solution is 21% of that in deoxygenated solution. The singlet oxygen quantum yields ?? of HMME and Gd(III)-HMME in air saturated methanol solution were determined to be 0.79 and 0.40 respectively using comparative spectra method. These phenomena indicate that the oxygen sensibility and production of singlet oxygen of Gd(III)-HMME can fulfill the requirement of PDT treatment. PMID:24663532

  10. High concentration of gadolinium ion modifying isolated rice mitochondrial biogenesis.

    PubMed

    Zhao, Jie; Jin, Jian-Cheng; Zhou, Zhi-Qiang; Xia, Cai-Fen; Yang, Xiao-Gang; Jiang, Feng-Lei; Dai, Jie; Liu, Yi

    2013-12-01

    Mitochondria play an important role in plant growth and development, cooperating with the endoplasmic reticulum and nucleus. Gadolinium, one of the rare earth elements, is an inhibitor of stretch-activated calcium channels located on the endoplasmic reticulum and plasma membrane and has no effect on nuclear calcium variation in plant cells. We analyzed the effects of Gd3+ on mitochondria function by monitoring mitochondrial swelling, changes of membrane fluidity, and transmembrane potential collapse and by observing mitochondrial ultrastructure. We found that high concentration of Gd3+ induces rice mitochondrial dysfunction through mitochondrial permeability transition (MPT). The protection of DTT and EDTA demonstrate that Gd3+ blocks the inner membrane ion channel through thiol chelation. PMID:24078325

  11. Mechanism of inhibition of ribonucleotide reductase with motexafin gadolinium (MGd)

    SciTech Connect

    Zahedi Avval, Farnaz; Berndt, Carsten; Pramanik, Aladdin [Department of Medical Biochemistry and Biophysics, Karolinska Institute, SE-17177 Stockholm (Sweden); Holmgren, Arne [Department of Medical Biochemistry and Biophysics, Karolinska Institute, SE-17177 Stockholm (Sweden)], E-mail: arne.holmgren@ki.se

    2009-02-13

    Motexafin gadolinium (MGd) is an expanded porphyrin anticancer agent which selectively targets tumor cells and works as a radiation enhancer, with promising results in clinical trials. Its mechanism of action is oxidation of intracellular reducing molecules and acting as a direct inhibitor of mammalian ribonucleotide reductase (RNR). This paper focuses on the mechanism of inhibition of RNR by MGd. Our experimental data present at least two pathways for inhibition of RNR; one precluding subunits oligomerization and the other direct inhibition of the large catalytic subunit of the enzyme. Co-localization of MGd and RNR in the cytoplasm particularly in the S-phase may account for its inhibitory properties. These data can elucidate an important effect of MGd on the cancer cells with overproduction of RNR and its efficacy as an anticancer agent and not only as a general radiosensitizer.

  12. Application of ultrasound in solvent extraction of nickel and gallium

    SciTech Connect

    Pesic, B.

    1996-07-01

    The effects of ultrasound on the rate of solvent extraction of nickel with Lix 65N and Lix 70, and gallium with Kelex 100 were investigated. These solvent extraction systems are noted by their sluggish nature. Low frequency (20 kHz) ultrasound increased the rates of extraction of nickel by factors of four to seven. The ultrasound had no effect on the final chemical equilibrium. Gallium extraction rates were enhanced with the use of ultrasound by as much as a factor of 15. Again, the ultrasound had no effect on extraction equilibrium. For both nickel and gallium, the enhanced rates were attributed to increased interfacial surface area associated with ultrasonically induced cavitation and microdroplet formation. The stability of the microdroplets permitted intermittent application of ultrasound with corresponding decreases in ultrasonic energy requirements. The lowest energy consumption was observed with short (0.25 to 5 s) bursts of high power (41 to 61 W) ultrasonic inputs. The study also provided insight into the factors that affect the complex extraction of gallium from sodium aluminate solutions. The rate controlling step was found to be the dehydration of the gallate ion, Ga(OH)4, and the first complex formation between gallium and Kelex 100. Sodium was found to enhance the extraction rate up to a point, beyond which increased concentration was detrimental. Increasing aluminum concentration was found to slow extraction rates. Modifiers and diluents were shown to markedly affect extraction rates even without ultrasound. Ketone modifiers, particularly 2-undecanone, when used with Kermac 470B or Escaid 200 diluents enhanced extraction rates of gallium to the point that the use of ultrasound provided no additional benefits. The positive effects of ketone modifiers for the solvent extraction of gallium had not been previously reported.

  13. Exsolution halos surrounding ruptured inclusions in garnets from UHT and UHP rocks

    NASA Astrophysics Data System (ADS)

    Axler, Jennifer; Ague, Jay

    2015-04-01

    Distinctive halos of rutile ± apatite needles and/or plates centered on quartz or multiphase inclusions with radial cracks in garnet are investigated. The quartz is likely former coesite and the multiphase inclusions are interpreted to be decrepitated fluid inclusions. We study samples from two localities: (1) ultrahigh-temperature (UHT) metapelitic gneisses from the Central Maine Terrane in Connecticut, USA (Ague et al., 2013) (rutile halos only) and (2) ultrahigh-pressure (UHP) diamondiferous saidenbachite from the Saxonian Erzgebirge (Massonne, 2003) (rutile and apatite halos). The rutile and apatite needles in the halos are typically oriented in three directions. Within the halos, garnet is depleted in Ti (and P if apatite is present). The halos extend about three inclusion radii away from the central quartz or multiphase inclusions. We propose that the inclusion halos of rutile ± apatite formed by exsolution out of garnet due to rupturing of the central inclusions. The internal pressure of an inclusion in garnet can be larger than the surrounding lithostatic pressure if the entrapment pressure is maintained or if a large positive volume phase change occurs. A large pressure difference between an inclusion and host strains the host and causes deformation, which in turn produces dislocations and other defects. During exhumation the pressure difference between inclusions and the surrounding rock matrix can become so great that rupturing of the garnet occurs. The rupturing creates more dislocations and defects in the garnet with the dislocation density highest around the inclusion. The defects in the crystal structure are ideal nucleation sites for exsolved precipitates. Another factor assisting exsolution is the drop in pressure in the surrounding garnet caused by the rupturing which should in turn decrease the solubility of Ti and P in garnet. To test the exsolution hypothesis, chemical reintegration of the Ti or P contents of the garnet in the halos plus the rutile or apatite precipitates was done using wide-beam electron probe microanalyzer methods. The reintegrated concentrations are consistent with the Ti or P being sourced from the garnet; no external sources for these elements were necessary. Additional hypothesis tests include: (1) The abundances of rutile ± apatite precipitates are highest closest to the ruptured inclusions as expected for strongly-localized stress and resulting deformation. (2) The radii of the halos are proportional to the radii of the ruptured inclusions. This is consistent with the elastic (pressure vessel) model for a strong single host crystal which predicts that stress will drop off proportional to the inverse of the radial distance cubed. (3) The rutile ± apatite inclusions are rare or absent elsewhere in the garnets, even where Ti or P concentrations are high. The exsolved halos of rutile ± apatite demonstrate that strain can be important for driving mineral exsolution from garnet. For this process to occur, Ti ± P must be present in aluminous garnet. Elevated concentrations of these elements are typically found in garnets from HP, UHP, granulite, or UHT settings. Thus, the textures we describe are likely to be restricted to such metamorphic environments.

  14. Outcome of erbium:yttrium aluminium garnet laser resurfacing treatments.

    PubMed

    Cole, R P; Widdowson, D; Moore, J C

    2008-10-01

    Erbium:yttrium aluminium garnet (erbium:YAG) laser treatment was used to resurface skin abnormalities in patients suffering from conditions that included epidermal naevi, tuberous sclerosis, angiofibromata, neurofibromatosis, and scarring caused by acne or other means. Patients completed self-report questionnaires before their first laser test patch session, and again approximately 4 months after one treatment, so that its success could be evaluated from the patient's perspective. Disability and distress were quantified with the University of York Health Measurement Questionnaire (HMQ). Satisfaction with appearance was measured with a specifically designed Salisbury Appearance Scale (SAS) questionnaire. Pretreatment questionnaires were completed by 108 (HMQ) and 80 (SAS) patients. Thirty-six (HMQ) and 22 (SAS) patients completed a full treatment during the study period. Some patients had a test patch only during the study period. Others decided against further treatment after the test patch. Control SAS questionnaires were completed by 29 subjects on two occasions and showed no change over time. There was a significant improvement in patient satisfaction with appearance (SAS), but there was no significant difference in the disability and distress (HMQ) after erbium:YAG resurfacing. PMID:18074165

  15. The REE budget of garnet, clinopyroxene and orthopyroxene from garnet-peridotites: Comparison of kimberlite and alkali-basalt hosted mantle xenoliths

    Microsoft Academic Search

    B. Mocek; D. Ionov; F. R. Boyd

    2003-01-01

    Trace element concentrations and distribution of mantle minerals are important in understanding mantle melting processes. Discrepancies exist between experimentally determined partition coefficients and those collected from natural rocks and minerals. To reconcile these we used natural mantle xenoliths from South Africa and Siberia to determine trace element partitioning, especially for REE, between garnet (grt), clinopyroxene (cpx) and orthopyroxene (opx) directly

  16. Garnet and muscovite chemistry of Paleoproterozoic basement in Brasília Belt: preserved magmatic compositions

    NASA Astrophysics Data System (ADS)

    Sousa, Isabela

    2015-04-01

    In central Brazil, a wide area of Paleoproterozoic granitic rocks is exposed in northern Brasília Belt. These rocks were formed in a Rhyacian orogeny and underwent at least two deformational events: the first, coeval with emplacement of granitic rocks, reached low amphibolite facies. The second deformational event is the Brasiliano Orogeny, responsible for reequilibration in greenschist facies during Neoproterozoic. Neoformation of white mica and epidote, plagioclase decalcification, quartz recrystallization and biotite chloritization seen in samples record the effects of Neoproterozoic greenschist metamorphism. Despite the geological history of rocks from this terrane, muscovite and garnet grains still preserve magmatic composition. Electron microprobe analysis was used to investigate muscovite and garnet. For the muscovite, as the purpose of this investigation is to certify their magmatic composition, chosen grains were the relatively coarse, subhedral to euhedral and not enclosed by minerals from which muscovite might have formed from alteration. In terms of Ti, Mg and Na, most grains have primary composition with relatively high contents of Ti, as expected for magmatic muscovite, once at higher temperatures, Ti solubility is lower. Muscovite grains with TiO2 > 0.9% have undoubtedly primary composition, but other grains have a more discrete enrichment in TiO2 (0.4 to 0.6%) and are interpreted as reequilibrated grains. Analyzed garnet grains are all plotted within the field of magmatic garnet composition after Miller and Stoddard (1981), and are typical almandine-spessartine solid solutions, with minor grossular and pyrope component, according to calculation based on 12 oxygens. Spessartine-rich garnet is probably formed in relatively evolved magmas with high Al and low Ti contents, otherwise, Mn would be incorporated in ilmenite, especially in high ƒO2 conditions. In a hasty interpretation, it is possible to suppose both garnet and muscovite are secondary phases that had their formation related to metamorphic events. Especially considering Brasiliano and Paleoproterozoic orogenies affected these rocks. However, mineral chemistry indicates muscovite and garnet are magmatic phases.

  17. Comparison of Lithium Gadolinium Borate Crystal Shards in Scintillating and Nonscintillating Plastic Matrices

    Microsoft Academic Search

    Kareem Kazkaz; Nathaniel S. Bowden; Marisa Pedretti

    2011-01-01

    We present a method for detecting neutrons using scintillating lithium gadolinium borate crystal shards in a plastic matrix while maintaining high gamma rejection. We have procured two cylindrical detectors, 5\\

  18. Theoretical study of structure and stability of small gadolinium carboxylate complexes in liquid scintillator solvents.

    PubMed

    Huang, Pin-Wen

    2014-09-01

    The structural properties of three small gadolinium carboxylate complexes in three liquid scintillator solvents (pseudocumene, linear alkylbenzene, and phenyl xylylethane) were theoretically investigated using density functional theory (B3LYP/LC-RECP) and polarizable continuum model (PCM). The average interaction energy between gadolinium atom and carboxylate ligand (E(int)) and the energy difference of the highest singly occupied molecular orbital and lowest unoccupied molecular orbital (?(SL)) were calculated to evaluate and compare the relative stability of these complexes in solvents. The calculation results show that the larger (with a longer alkyl chain) gadolinium carboxylate complex has greater stability than the smaller one, while these gadolinium carboxylates in linear alkylbenzene were found to have greater stability than those in the other two solvents. PMID:25204583

  19. Gadolinium-doped organosilicon films grown by plasma chemical vapor deposition

    Microsoft Academic Search

    J. Tyczkowski; H. Szymanowski; R. Dargis

    1999-01-01

    Thin organosilicon films doped with gadolinium were prepared by plasma chemical vapor co-deposition (13.56MHz) using hexamethyldisiloxane as a precursor for the light-guide matrix, and tris(2,2,6,6-tetramethyl-3-5-heptanedionato)gadolinium(III) as a source of luminescent centers. The chemical composition of such films was investigated by Fourier transform infrared spectroscopy and quantitative microanalysis. Measurements of optical (ultraviolet–visible) absorption and photoluminescence were also performed. It was found

  20. Specific Heat of Gadolinium, Terbium, Dysprosium, Holmium, and Thulium Metals between 3 and 25°K

    Microsoft Academic Search

    O. V. Lounasmaa; Lorna J. Sundström

    1966-01-01

    The specific heat of gadolinium, terbium, dysprosium, holmium, and thulium metals has been measured between 3 and 25°K using a germanium resistance thermometer. Anomalies, apparently associated with magnetic transformations in the metals themselves, were found for terbium at 16°K and for holmium at 17.5°K. Low-temperature peaks, probably resulting from impurities, were observed for gadolinium, terbium, and dysprosium. By assuming that

  1. Influence of gadolinium on magnetization and DC resistivity of Ni-Zn nanoferrites

    Microsoft Academic Search

    A. Mahesh Kumar; M. Chaitanya Varma; G. S. V. R. K. Choudary; P. Prameela; K. H. Rao

    2012-01-01

    The study of gadolinium substitution in small amounts on the saturation magnetization and DC resistivity of nickel-zinc nanoferrite has led to the understanding of the degree of formation of a secondary orthoferrite GdFeO 3 phase, the generation of cationic and oxygen vacancies and the dilution of gadolinium in the lattice. The role of secondary phase in modifying the electromagnetic properties

  2. Specific Heat of Gadolinium and Ytterbium Metals between 0.4 and 4°K

    Microsoft Academic Search

    O. V. Lounasmaa

    1963-01-01

    The heat capacities of gadolinium and ytterbium metals have been measured between 0.4 and 4°K in a He3 cryostat. For gadolinium, in qualitative agreement with earlier results, anomalous humps were observed in Cp at 1.1, 1.6, and 3.7°K. The ground state of the Gd3+ ion is 8S72 and consequently, due to zero orbital angular momentum of the 4f electrons, the

  3. The clinical significance of gadolinium enhancement of lumbar disc herniations and nerve roots on preoperative MRI

    Microsoft Academic Search

    P. C. A. J. Vroomen; S. J. M. Van Hapert; R. E. H. Van Acker; E. A. M. Beuls; A. G. H. Kessels; J. T. Wilmink

    1998-01-01

    The clinical significance of preoperative gadolinium DPTA enhancement around disc herniations and in the epidural space on\\u000a MRI is not clear. The relation of nerve root enhancement to dysfunction also remains controversial. To investigate the clinical\\u000a significance of contrast enhancement we looked at the symptoms and signs and gadolinium DPTA-enhanced images of 71 consecutive\\u000a surgical candidates in a standardised fashion.

  4. Gadolinium Use in Spine Pain Management Procedures for Patients with Contrast Allergies: Results in 527 Procedures

    SciTech Connect

    Safriel, Yair [Yale University School of Medicine, Neuroradiology Section, Department of Radiology (United States)], E-mail: safriel@yale.edu; Ang, Roberto [Center for Diagnostic Imaging (United States); Ali, Muhammed [Kaiser Permanente Woodland Hills Medical Center (United States)

    2008-03-15

    Introduction. To review the safety and efficacy of gadolinium in spine pain management procedures in patients at high risk for a contrast reaction and who are not suitable candidates for the use of standard non-ionic contrast. Methods. We reviewed records over a 61-month period of all image-guided spinal pain management procedures where patients had allergies making them unsuitable candidates for standard non-ionic contrast and where gadolinium was used to confirm needle tip placement prior to injection of medication. Results. Three hundred and four outpatients underwent 527 procedures. A spinal needle was used in all but 41 procedures. Gadolinium was visualized using portable C-arm fluoroscopy in vivo allowing for confirmation of needle tip location. The gadolinium dose ranged from 0.2 to 10 ml per level. The highest dose received by one patient was 15.83 ml intradiscally during a three-level discogram. Three hundred and one patients were discharged without complication or known delayed complications. One patient had documented intrathecal injection but without sequelae and 2 patients who underwent cervical procedures experienced seizures requiring admission to the intensive care unit. Both the latter patients were discharged without any further complications. Conclusion. Based on our experience we recommend using gadolinium judiciously for needle tip confirmation. We feel more confident using gadolinium in the lumbar spine and in cervical nerve blocks. Gadolinium should probably not be used as an injectate volume expander. The indications for gadolinium use in cervical needle-guided spine procedures are less clear and use of a blunt-tipped needle should be considered.

  5. Hydrated clearance of gadolinium-DTPA as a measurement of glomerular filtration rate

    Microsoft Academic Search

    Peter L Choyke; Howard A Austin; Joseph A Frank; Mary E Girton; Richard L Diggs; Andrew J Dwyer; LaGrieta Miller; Robert Nussenblatt; Henry McFarland; Theodore Simon

    1992-01-01

    Hydrated clearance of gadolinium-DTPA as a measurement of glomerular filtration rate. Technetium (99mTc)-diethylene triamine pentaacetic acid (DTPA) hydrated clearance studies are accurate for determining GFR but require special facilities for handling and measuring samples. We investigated the potential of a non-radioactive paramagnetic analog, Gadolinium (Gd)-diethylene triamine pentaacetic acid (DTPA), an approved NMR contrast agent, as a glomerular filtration marker. Instead

  6. Preliminary Spectroscopic Measurements for a Gallium Electromagnetic (GEM) Thruster

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Burton, Rodney L.; Glumac, Nick G.; Polzin, Kurt A.

    2007-01-01

    As a propellant option for electromagnetic thrusters, liquid ,gallium appears to have several advantages relative to other propellants. The merits of using gallium in an electromagnetic thruster (EMT) are discussed and estimates of discharge current levels and mass flow rates yielding efficient operation are given. The gallium atomic weight of 70 predicts high efficiency in the 1500-2000 s specific impulse range, making it ideal for higher-thrust, near-Earth missions. A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma and estimate electron temperature. The spectra show that neutral, singly, and doubly ionized gallium species are present in a 20 J, 1.8 kA (peak) are discharge. With graphite present on the insulator to facilitate breakdown, singly and doubly ionized carbon atoms are also present, and emission is observed from molecular carbon (CZ) radicals. A determination of the electron temperature was attempted using relative emission line data, and while the spatially and temporally averaged, spectra don't fit well to single temperatures, the data and presence of doubly ionized gallium are consistent with distributions in the 1-3 eV range.

  7. Gadolinium Contrast Agent-Induced CD163+ Ferroportin+ Osteogenic Cells in Nephrogenic Systemic Fibrosis

    PubMed Central

    Swaminathan, Sundararaman; Bose, Chhanda; Shah, Sudhir V.; Hall, Kimberly A.; Hiatt, Kim M.

    2014-01-01

    Gadolinium-based contrast agents are linked to nephrogenic systemic fibrosis in patients with renal insufficiency. The pathology of nephrogenic systemic fibrosis is characterized by abnormal tissue repair: fibrosis and ectopic ossification. The mechanisms by which gadolinium could induce fibrosis and ossification are not known. We examined in vitro the effect of a gadolinium-based contrast agent on human peripheral blood mononuclear cells for phenotype and function relevant to the pathology of nephrogenic systemic fibrosis using immunofluorescence, flow cytometry, real-time PCR, and osteogenic assays. We also examined tissues from patients with nephrogenic systemic fibrosis, using IHC to identify the presence of cells with phenotype induced by gadolinium. Gadolinium contrast induced differentiation of human peripheral blood mononuclear cells into a unique cellular phenotype—CD163+ cells expressing proteins involved in fibrosis and bone formation. These cells express fibroblast growth factor (FGF)23, osteoblast transcription factors Runt-related transcription factor 2, and osterix, and show an osteogenic phenotype in in vitro assays. We show in vivo the presence of CD163+/procollagen-1+/osteocalcin+ cells in the fibrotic and calcified tissues of nephrogenic systemic fibrosis patients. Gadolinium contrast–induced CD163+/ferroportin+/FGF23+ cells with osteogenic potential may play a role in systemic fibrosis and ectopic ossification in nephrogenic systemic fibrosis. PMID:23867799

  8. Application of extracellular gadolinium-based MRI contrast agents and the risk of nephrogenic systemic fibrosis.

    PubMed

    Heverhagen, J T; Krombach, G A; Gizewski, E

    2014-07-01

    Nephrogenic systemic fibrosis (NSF) is a serious, sometimes fatal disease. Findings in recent years have shown that a causal association between gadolinium containing contrast media and NSF is most likely. Therefore, the regulatory authorities have issued guidelines on the use of gadolinium-containing contrast media which have reduced the number of new cases of NSF to almost zero. However, it is for precisely this reason that the greatest care must still be taken to ensure that these guidelines are complied with. The most important factors are renal function, the quantity of gadolinium administered and coexisting diseases such as inflammation. All of these factors crucially influence the quantity of gadolinium released from the chelat in the body. This free gadolinium is thought to be the trigger for NSF. Other important factors are the stability of the gadolinium complex and furthermore the route of its elimination from the body. Partial elimination via the liver might be an additional protective mechanism. In conclusion, despite the NSF risk, contrast-enhanced MRI is a safe diagnostic procedure which can be used reliably and safely even in patients with severe renal failure, and does not necessarily have to be replaced by other methods. PMID:24477507

  9. Thermodynamic Properties of Rock-Forming Garnets: How Well Known are They?

    NASA Astrophysics Data System (ADS)

    Geiger, C. A.; Dachs, E.

    2011-12-01

    Garnet is an important rock-forming mineral whose geological occurrence is widespread. The silicate garnets (E3G2Si3O12) show extensive compositional variability and the various end-members are stable over an enormous range of rock compositions and pressure and temperature conditions. Extensive geothermometry and geobarometry studies involving garnet have been made. Thus, much research has been done to determine garnet's thermodynamic properties. There are now several internally consistent mineralogical thermodynamic databases and their use is widespread. It is common belief in some/many circles that the present databases represent "the final word" on thermodynamic properties at least in terms of most end-member silicates. The question arises - How true is this assumption in the case of garnet? We have been and are presently engaged in investigating the thermodynamic properties of garnet, where volumetric properties and heat-capacity behavior play a central role. The volumes of the various end-member garnets are now known precisely. Only secondary effects arising from extra minor components (e.g., OH-,Fe3+,Mn3+) have yet to be worked out exactly. In terms of heat capacity Cp behavior, new calorimetric data allow improved understanding. Low T calorimetric measurements on spessartine were made recently and show that previous estimates for S° were in error (Dachs et al. 2009). New unpublished calorimetric results on grossular appear to have resolved long-standing uncertainty regarding its precise S° value. S° for silica-free hydrogrossular has also been determined for the first time. Cp measurements are now focusing on almandine and here low T electronic and magnetic properties must be considered. One can conclude that Cp, S°, ?H°f, V and ?G°f for the common silicate garnet end-members are now well determined to about 1000 K. Cp behavior above roughly 1000 K is less certain for some garnets (e.g., almandine, spessartine). What about thermodynamic behavior of garnet solid solutions? Here, there is much less is known (Geiger 1999). The precise mixing behavior of most garnet binaries, for example, is not understood. An exception is the pyrope-grossular binary, which has now been investigated numerous times and some consensus on its mixing properties now exist. In a related area, crystal-chemical investigations are providing good insight on possible macroscopic thermodynamic mixing behavior. Here, for example, low temperature synchrotron measurements on line broadening of powder diffraction lines give the first quantitative lattice-strain determinations on a solid solution (Dapiaggi et al. 20005). The asymmetric nature of the mixing functions ?Hex, ?Sex, and ?Vex can be explained via strain and local Ca/Mg-O bond behavior. Another area needing further investigation is short-range order. 29Si NMR spectroscopic study of synthetic Py-Gr garnets indicates that some short-range Ca-Mg order may be present. Bosenick et al. (1999) estimate that configurational entropy effects of about 2 J/mole.K may result at T > 1000 °C. It remains to be determined, however, what the structural state is at lower temperatures of 600 to 900 °C. The degree of short-range order could be substantial in metamorphic garnet solid solutions.

  10. Vapor-Phase Garnet at Yucca Mountain, Nevada: Geochemistry and Oxygen-Isotope Thermometry

    SciTech Connect

    R. J. Moscati; C.A. Johnson; J.F. Whelan

    2001-07-03

    About 20 vapor-phase garnets were studied in two samples of the Topopah Spring Tuff from Yucca Mountain, in southern Nevada. The Miocene-age Topopah Spring Tuff is a 350-m-thick, devitrified, moderately to densely welded ash flow that is compositionally zoned from high-silica rhyolite to quartz latite. During cooling of the tuff, escaping vapor produced lithophysae (former gas cavities) lined with an assemblage of tridymite, cristobalite, alkali feldspar, and locally, hematite and/or garnet. Vapor-phase topaz and economic deposits (such as porphyry molybdenum-tungsten) commonly associated with topaz-bearing rhyolites (characteristically enriched in fluorine) were not found in the Topopah Spring Tuff at Yucca Mountain. The garnets are not primary igneous phenocrysts, but rather crystals that grew from a fluorine-poor magma-derived vapor trapped during emplacement of the tuff. The garnets are euhedral, vitreous, reddish brown, trapezohedral, as large as 2 mm in diameter, and fractured. The garnets also contain inclusions of tridymite. Electron-microprobe analyses of the garnets reveal that they are almandine-spessartine (48.0 and 47.9 mol percent, respectively), have an average chemical formula of (Fe{sub 1.46}, Mn{sub 1.45}, Mg{sub 0.03}, Ca{sub 0.10}) (Al{sub 1.93}, TiO{sub 0.02}) Si{sub 3.01}O{sub 12}, and are homogeneous in Fe and Mn concentrations from core to rim. Composited garnets from each sample site have {delta}{sup 18}O values of 7.2 and 7.4{per_thousand}. The coexisting tridymite, however, has {delta}{sup 18}O values of 17.4 and 17.6{per_thousand} values indicative of reaction with later, low-temperature water. Unaltered tridymite from higher in the stratigraphic section has a {delta}{sup 18}O of 11.1{per_thousand} which, when coupled with the garnet {delta}{sup 18}O values in a quartz-garnet fractionation equation, indicates vapor-phase crystallization at temperatures of almost 600 C. This high-temperature mineralization, formed during cooling of the tuffs, is distinct from the later and commonly recognized low-temperature stage (generally 50-70 C) of calcite, quartz, and opal secondary mineralization, formed from percolating meteoric water, that locally coats fracture footwalls and lithophysal floors.

  11. Lithium Behavior during Growth of Metasedimentary Garnets from the Cignana UHP Locality, Italy

    NASA Astrophysics Data System (ADS)

    Bebout, G. E.; Tsujimori, T.; Ota, T.; Shimaki, Y.; Kunihiro, T.; Carlson, W. D.; Nakamura, E.

    2014-12-01

    We investigated major and trace element concentrations and ?7Li in garnets in Lago di Cignana metasedimentary rocks (peak conditions ~550?C, 2.5-3.0 GPa), following the EPMA-SIMS approach of Tsujimori et al. (2014; IMA conference abstract). Previous work on the devolatilization history of these rocks (Bebout et al., 2013; Cook-Kollars et al., 2014; both in Chemical Geology) provides a petrologic and geochemical context for this study. Lithium is of interest as a tracer of fluid-rock interactions and because of its potential to isotopically fractionate during diffusional processes. All garnets are almandine-rich with strongly decreasing MnO and increasing MgO toward rims. HREEs, Y, and Li also show strong zoning, with elevated concentrations in cores (15-50 ppm Li) and marked high-concentration anomalies (up to 117 ppm Li, 5500 ppm Y), with little or no major element shift, as growth annuli at which some garnets have elevated ?7Li. In all garnets, rutile inclusions appear abruptly at annuli and outward toward rims, accompanied by inclusions of a Ca- and LREE-rich phase and decreased Nb concentrations in garnet. These relationships appear to reflect prograde garnet-forming reaction(s) that in part involved titanite breakdown to stabilize rutile, which resulted in delivery of more abundant Y and HREEs at surfaces of growing garnets to produce growth annuli. The co-enrichment of Li and Y+REEs is attributed to their mutual incorporation via a charge-coupled substitution (Carlson et al., 2014; American Mineralogist); thus the increased Li uptake is a passive consequence of the elevated concentrations of Y+REEs. Distributions of ?7Li are complex, with most garnets showing only subtle core-to-rim variation other than at Y+REE annuli. At annuli, some garnets display elevated ?7Li (by up to 8‰), while others in the same rock do not. Small-scale fluctuations in ?7Li may correlate with abrupt shifts in major and trace element concentrations, suggesting that changes in the minerals involved as reactants exert some control on the evolution of ?7Li.

  12. Prograde eclogitization preserved in zoned garnet from Guatemalan jadeite-lawsonite eclogites

    NASA Astrophysics Data System (ADS)

    Ota, T.; Tsujimori, T.; Nakamura, E.

    2011-12-01

    Metamorphic zoned garnet in high-pressure, low-temperature (HP-LT) eclogite acts as a time capsule. Because of very slow-internal diffusion and low-plasticity at temperatures below 600 °C, garnet interiors are isolated from the system during crystal growth. In order to track growth history of zoned garnet and environmental changes during eclogitization of oceanic crust, euhedral garnet porphyroblasts (5-9 mm) have been extracted from very HP-LT basaltic eclogites (lawsonite eclogites from South of Motagua fault, Guatemala) and have been cut in half at the center for a petrological and geochemical study. The investigated garnets are strongly zoned with spessartine-rich cores, explained by Raleigh-like fractionation in Mn; Mg/(Mg+Fe) increases continuously from core to rim. Micron- to submicron-scale oscillatory zoning of Mn was observed at the rims. Excepting the oscillatory-zoned rims, garnets have abundant mineral inclusion of jadeite, whereas all matrix pyroxenes are omphacitic. Predominant mineral assemblage is jadeite (with omphacite patches) + lawsonite + rutile ± phengite; micro zircons are common but show limited distribution. Jadeite inclusions exhibit irregular shapes in various sizes. Although each individual inclusion shows compositional heterogeneity, textures of each jadeite inclusions can be connected up together like a torn-paper collage. Some jadeite inclusions are partially replaced by secondary albite; rutile is replaced by titanite. New growth of secondary grossular-rich euhedral garnet and glaucophane are found within albite after jadeitite. Omphacite inclusions show distinct antiphase domains structure. In-situ SIMS trace- element analyses in 20-30 micron steps revealed (1) sharp peaks of HREE (excepting Dy), Li and Y, and (2) "M"-shape shoulder spikes of Dy, Hf, and Er at the mantle. These characteristics indicate: (1) eclogite-facies garnets started to grow along brittle fractures of jadeitic pyroxene-rich matrix; (2) the rapid garnet growth captured not only pre-eclogite minerals but also texture of precursor rocks; and (3) prograde mineral assemblages in the matrix were completely modified during exhumation. With subduction to greater depths, jadeite-lawsonite-bearing (glaucophane-free) metabasalt transforms to jadeite-lawsonite eclogite; in other words, blueschist (glaucophane schist) is not necessary as precursor to prograde eclogite in very cold subduction zone.

  13. Measuring Nanoscale Heat Transfer for Gold-(Gallium Oxide)-Gallium Nitride Interfaces as a Function

    NASA Astrophysics Data System (ADS)

    Szwejkowski, Chester; Sun, Kai; Constantin, Costel; Giri, Ashutosh; Saltonstall, Christopher; Hopkins, Patrick; NanoSynCh Team; Exsite Team

    2014-03-01

    Gallium nitride (GaN) is considered the most important semiconductor after the discovery of Silicon. Understanding the properties of GaN is imperative in determining the utility and applicability of this class of materials to devices. We present results of time domain thermoreflectance (TDTR) measurements as a function of surface root mean square (RMS) roughness. We used commercially available 5mm x 5mm, single-side polished GaN (3-7 ?m)/Sapphire (430 ?m) substrates that have a Wurtzite crystal structure and are slightly n-type doped. The GaN substrates were annealed in the open atmosphere for 10 minutes (900-1000 °C). This high-temperature treatment produced RMS values from 1-60 nm and growth of gallium oxide (GaO) as measured with an atomic force microscopy and transmission electron microscopy respectively. A gold film (80nm) was deposited on the GaN surface using electron beam physical vapor deposition which was verified using ellipsometry and profilometry. The TDTR measurements suggest that the thermal conductivity decays exponentially with RMS roughness and that there is a minimum value for thermal boundary conductance at a roughness of 15nm.

  14. Investigation on gallium ions impacting monolayer graphene

    NASA Astrophysics Data System (ADS)

    Wu, Xin; Zhao, Haiyan; Yan, Dong; Pei, Jiayun

    2015-06-01

    In this paper, the physical phenomena of gallium (Ga+) ion impacting monolayer graphene in the nanosculpting process are investigated experimentally, and the mechanisms are explained by using Monte Carlo (MC) and molecular dynamics (MD) simulations. Firstly, the MC method is employed to clarify the phenomena happened to the monolayer graphene target under Ga+ ion irradiation. It is found that substrate has strong influence on the damage mode of graphene. The mean sputtering yield of graphene under 30 keV Ga+ ion irradiation is 1.77 and the least ion dose to completely remove carbon atoms in graphene is 21.6 ion/nm2. Afterwards, the focused ion beam over 21.6 ion/nm2 is used for the irradiation on a monolayer graphene supported by SiO2 experimentally, resulting in the nanostructures, i.e., nanodot and nanowire array on the graphene. The performances of the nanostructures are characterized by atomic force microscopy and Raman spectrum. A plasma plume shielding model is put forward to explain the nanosculpting results of graphene under different irradiation parameters. In addition, two damage mechanisms are found existing in the fabrication process of the nanostructures by using empirical MD simulations. The results can help us open the possibilities for better control of nanocarbon devices.

  15. Gallium nitride micromechanical resonators for IR detection

    NASA Astrophysics Data System (ADS)

    Rais-Zadeh, Mina

    2012-06-01

    This paper reports on a novel technology for low-noise un-cooled detection of infrared (IR) radiation using a combination of piezoelectric, pyroelectric, electrostrictive, and resonant effects. The architecture consists of a parallel array of high-Q gallium nitride (GaN) micro-mechanical resonators coated with an IR absorbing nanocomposite. The nanocomposite absorber converts the IR energy into heat with high efficiency. The generated heat causes a shift in frequency characteristics of the GaN resonators because of pyroelectric effect. IR detection is achieved by sensing the shift in the resonance frequency and amplitude of the exposed GaN resonator as compared to a reference resonator that is included in the array. This architecture offers improved signal to noise ratio compared with conventional pyroelectric detectors as the resonant effect reduces the background noise and improves sensitivity, enabling IR detection with NEDTs below 5 mK at room temperature. GaN is chosen as the resonant material as it possesses high pyroelectric, electrostrictive, and piezoelectric coefficients and can be grown on silicon substrates for low-cost batch fabrication. Measured results of a GaN IR detector prototype and a thin-film nanocomposite IR absorber are presented in this paper.

  16. Gallium nitride photocathodes for imaging photon counters

    NASA Astrophysics Data System (ADS)

    Siegmund, Oswald H. W.; Hull, Jeffrey S.; Tremsin, Anton S.; McPhate, Jason B.; Dabiran, Amir M.

    2010-07-01

    Gallium nitride opaque and semitransparent photocathodes provide high ultraviolet quantum efficiencies from 100 nm to a long wavelength cutoff at ~380 nm. P (Mg) doped GaN photocathode layers ~100 nm thick with a barrier layer of AlN (22 nm) on sapphire substrates also have low out of band response, and are highly robust. Opaque GaN photocathodes are relatively easy to optimize, and consistently provide high quantum efficiency (70% at 120 nm) provided the surface cleaning and activation (Cs) processes are well established. We have used two dimensional photon counting imaging microchannel plate detectors, with an active area of 25 mm diameter, to investigate the imaging characteristics of semitransparent GaN photocathodes. These can be produced with high (20%) efficiency, but the thickness and conductivity of the GaN must be carefully optimized. High spatial resolution of ~50 ?m with low intrinsic background (~7 events sec-1 cm-2) and good image uniformity have been achieved. Selectively patterned deposited GaN photocathodes have also been used to allow quick diagnostics of optimization parameters. GaN photocathodes of both types show great promise for future detector applications in ultraviolet Astrophysical instruments.

  17. Characterization of semi-insulating gallium arsenide

    NASA Astrophysics Data System (ADS)

    Blakemore, John S.

    1993-11-01

    The project was established 18 Nov. 1992 to continue for 12 months. Its purpose has been electrical and optical characterization of samples from semi-insulating (SI) melt-grown crystals of gallium arsenide (GaAs). As a further definition of the project's purpose, the primary goal has been to assist NRL in assessing the properties of SI GaAs crystals grown at NRL by the vertical zone melt (VZM) method. A second aspect of this characterization work has involved samples from SI GaAs crystals grown by various commercial vendors including samples of pre-synthesized GaAs evaluated for its suitability as starting 'feedstock' for VZM growth. Measurements made at Western Washington University (WWU) under the terms of this project accord with a Statement of Work provided at the outset. These have included the following: (1) low-field dc electrical transport data for SI GaAs samples, as functions of temperature; (2) near-infrared (NIR) transmittance/absorption spectra of polished slabs, with data concerning the well-known EL2 defect determined from NIR absorption strength and spectral form; and (3) mid-IR data on absorption caused by carbon acceptors in SI GaAs.

  18. Fe-Mn partitioning between garnet and ilmenite: experimental calibration and applications

    NASA Astrophysics Data System (ADS)

    Pownceby, Mark I.; Wall, Victor J.; O'Neill, Hugh St. C.

    1987-09-01

    A new mineralogic geothermometer based on the partitioning of Fe and Mn between garnet and ilmenite has been calibrated by reversal experiments in the P-T range 600 900° C, 2 and 5 kbars and for fO2=QFM. The results constitute a sensitive geothermometer applicable over a broad range of composition and conditions. Garnetilmenite thermometry has advantages relative to existing geothermometers because of its accurate calibration, marked temperature sensitivity and the chemical and structural simplicity of the crystalline solutions involved. Application to natural assemblages reveals that the garnet-ilmenite geothermometer yields temperatures that agree well with other estimates. The reactivity of, and relatively rapid Fe-Mn diffusion in ilmenite may lead to retrograde resetting of high temperature partition values, but these factors may be useful for estimating rock cooling rates. Analysis of the experimental data indicates minor positive deviations from ideality for Fe-Mn garnets and ilmenites. Absolute magnitudes of interaction parameters ( W AB) derived from a regression analysis are subject to considerable uncertainty. The partition coefficient is, however, strongly dependent on the difference between solution parameters. These differences are well constrained with a magnitude of W {FeMn/ilm}- W {FeMn/gar}?300 cal mol-1. The accuracy and applicability of garnet-ilmenite thermometry will improve with the availability of better thermodynamic data for garnet crystalline solutions.

  19. Effects of pressure and temperature on the silicon diffusivity of pyrope-rich garnet

    NASA Astrophysics Data System (ADS)

    Shimojuku, Akira; Kubo, Tomoaki; Kato, Takumi; Yoshino, Takashi; Nishi, Masayuki; Nakamura, Tomoki; Okazaki, Ryuji; Kakazu, Yuki

    2014-01-01

    We have determined the pressure and temperature dependencies of Si volume diffusion rates in a single crystal of Pyp75Alm15Gr10 garnet at 6-25 GPa and 1400-1800 °C by the 29Si tracer diffusion method. High-pressure experiments were conducted using the Kawai-type multi-anvil high-pressure apparatus. Diffusion profiles were obtained using secondary ion mass spectrometry in the depth-profiling mode. The Si diffusion coefficient in garnet (Dgt) is expressed by the Arrhenius equation: Dgt = D0 exp(-(E? + PV?)/RT), with log10D0 = -7.1 ± 1.7 m2/s, E? = 345 ± 56 kJ/mol, and V? = 4.7 ± 0.5 cm3/mol. Si diffusion seems to be the slowest in the major constituent elements in a pyrope-rich garnet and control rates of plastic deformation. The comparison between Si diffusion rates in garnet and wadsleyite/ringwoodite suggests that garnet has similar or slightly lower strength (at most ˜2 times) compared with wadsleyite, and has similar or slightly higher strength (at most ˜3 times) compared with ringwoodite at temperatures ranging from 900 to 1300 °C. Thus, strength contrast between subducted oceanic crust and underlying peridotite layer may be small at the mantle transition zone conditions. This result suggests that the separation of subducted oceanic crust from an underlying peridotite layer may not occur.

  20. Garnet-bearing rhyolite from Deh-Salm area, Lut block, Eastern Iran: anatexis of deep crustal rocks

    NASA Astrophysics Data System (ADS)

    Mirnejad, H.; Blourian, G. H.; Kheirkhah, M.; Akrami, M. A.; Tutti, F.

    2008-11-01

    Rhyolite from the Deh Salm area, Lut block, Iran, is a 10-km-long flow unit that crops out as a 6-m thick sub-horizontal sheet (<5° dip) underlain by agglomerate and overlain by crystal lithic tuff. The ryholite contains phenocrysts of garnet, plagioclase and amphibole phases residing in a cryptocrystalline groundmass consisting of plagioclase, K-feldspar and quartz. Euhedral garnet phases range in size from 0.2 to 3.0 mm, have inclusions of ilmenite, rutile, apatite and zircon, and show no reaction/resorption microtextures. Electron microprobe analysis reveals that the garnet is homogeneous, lacks substantial chemical zoning and is dominantly almandine with subordinate pyrope, grossular, spessartine and andradite. The absence of inclusions of metamorphic minerals within garnet as well as the lack of included metamorphic rock fragments in the host rhyolite rule out a xenocrystic origin for the garnet. The garnet phases have low CaO content and variable MnO concentration, resembling those formed from S-type magma. The host rhyolite contains quartz, K-feldspar, and amphibole, has normative corundum, and is peraluminous. Inclusions within garnet as well as the chemistry of the garnet and the host rhyolite suggest that the garnet is a phenocryst phase crystallized from a deep-rooted (>25 km) crustal-derived peraluminous magma. It is likely that the peraluminous feature of the magma, inherited from partial melting of metapelitic source rocks, has favoured crystallization of garnet. Upon rising to higher levels, the garnet phases were in equilibrium with the host magma and thus were preserved as relatively large euhedral crystals in the Deh-Salm rhyolite.

  1. Extremely-efficient, miniaturized, long-lived alpha-voltaic power source using liquid gallium

    NASA Technical Reports Server (NTRS)

    Snyder, G. Jeffrey (Inventor); Patel, Jagdishbhai (Inventor); Fleurial, Jean-Pierre (Inventor)

    2004-01-01

    A power source converts .alpha.-particle energy to electricity for use in electrical systems. Liquid gallium or other liquid medium is subjected to .alpha.-particle emissions. Electrons are freed by collision from neutral gallium atoms to provide gallium ions. The electrons migrate to a cathode while the gallium ions migrate to an anode. A current and/or voltage difference then arises between the cathode and anode because of the work function difference of the cathode and anode. Gallium atoms are regenerated by the receiving of electrons from the anode enabling the generation of additional electrons from additional .alpha.-particle collisions.

  2. Proximity effect induced magnetoresistance hysteresis loops in a topological insulator/YIG heterostructure

    NASA Astrophysics Data System (ADS)

    Montazeri, Mohammad; Lang, Murong; Onbasli, Mehmet C.; Kou, Xufeng; He, Liang; Ross, Caroline A.; Wang, Kang L.

    2014-03-01

    We experimentally demonstrate the proximity effect induced hysteretic magnetoresistance in an 8 quintuple layers of Bi2Se3 films grown on Gallium Gadolinium Garnet (GGG) (111) substrates with a 50 nm Yttrium Iron Garnet (YIG) buffer layer by molecular beam epitaxy. With in-plane and out-of-plane magnetic field, square wave shaped and butterfly shaped resistance hysteresis loops can be observed up to 25 K, respectively. The relationship between the hysteretic MR curves and the magnetic switching of the YIG will be discussed in the context of a proximity effect between the YIG and the TI.

  3. First results from the Soviet-American Gallium Experiment

    SciTech Connect

    Abazov, A.I.; Abdurashitov, D.N.; Anosov, O.L.; Eroshkina, L.A.; Faizov, E.L.; Gavrin, V.N.; Kalikhov, A.V.; Knodel, T.V.; Knyshenko, I.I.; Kornoukhov, V.N.; Mezentseva, S.A.; Mirmov, I.N.; Ostrinsky, A.I.; Petukhov, V.V.; Pshukov, A.M.; Revzin, N.Y.; Shikhin, A.A.; Timofeyev, P.V.; Veretenkin, E.P.; Vermul, V.M.; Zakharov, Y.; Zatsepin, G.T.; Zhandarov, V.I. (AN SSSR, Moscow (USSR). Inst. Yadernykh Issledovanij); Bowl

    1990-01-01

    The Soviet-American Gallium Experiment is the first experiment able to measure the dominant flux of low energy p-p solar neutrinos. Four extractions made during January to May 1990 from 30 tons of gallium have been counted and indicate that the flux is consistent with 0 SNU and is less than 72 SNU (68% CL) and less than 138 SNU (95% CL). This is to be compared with the flux of 132 SNU predicted by the Standard Solar Model. 10 refs., 4 figs., 1 tab.

  4. CCMR: Gallium Nitride Nanowire Growth and FET Devices Fabrication

    NSDL National Science Digital Library

    Liu, Alison

    2005-08-17

    Being able to develop a high yield procedure where the nanowire growth can be controlled and repeated is very important for building future nanosystems. One goal of the project was to control the nanowire growth by varying different conditions such as temperature and catalyst size. Growth of gallium nitride nanowires of controlled diameters and predetermined sites has successfully been done using gold as the catalysti, but nickel nanoparticles are more difficult to use. Because of its direct band gap semiconductor properties, gallium nitride nanowires are very useful for making electronic and optical nanodevices including field-effect transistor (FET) devices. The second goal of the project was to fabricate such devices.

  5. Multiplane gallium tomography in assessment of occupational chest diseases

    SciTech Connect

    Cordasco, E.M.; O'Donnell, J.; MacIntyre, W.; Demeter, S.; Gonzalez, L.; Eren, M.; McMahon, W.; Burns, D.; Feiglin, D.H. (Cleveland Clinic Foundation, OH (USA))

    1990-01-01

    Gallium-67 scintigraphy is helpful in the evaluation of inflammatory, respiratory diseases. Single-photon emission computed tomography (SPECT) provides three-dimensional tomographic reconstruction of radioisotope distribution in the body. The addition of SPECT to gallium-67 scanning in 27 patients demonstrated an improvement in the sensitivity for detecting the presence and extent of interstitial occupational lung disease. This technique may provide earlier detection of parenchymal lung changes than can the chest x-ray and planar scanning in some patients with asbestosis. Findings in six patients with asbestosis are reported.

  6. Pseudomembranous colitis: a possible role for Gallium scanning

    SciTech Connect

    Kramer, E.L.; Charap, M.; Sanger, J.J.; Tiu, S.S.

    1983-10-01

    A case of antibiotic-associated pseudomembranous colitis is presented in which the Gallium scan was the first diagnostic modality to alert the clinicians to the existence of an inflammatory bowel process. The mechanism of localization of the radiopharmaceutical in inflammatory bowel disease is discussed. Although colonoscopy is far more specific and should be the first-line diagnostic tool used in assessing the presence of pseudomembranous colitis, Gallium scanning may have a role in the follow-up of treatment and in cases of relapse.

  7. Garnet/high-silica rhyolite trace element partition coefficients measured by ion microprobe

    USGS Publications Warehouse

    Sisson, T.W.; Bacon, C.R.

    1992-01-01

    Garnet/liquid trace element partition coefficients have been measured in situ by ion microprobe in a rhyolite from Monache Mountain, California. Partition coefficients are reported for La, Ce, Nd, Sm, Dy, Er, Yb, Sc, Ti, V, Cr, Sr, Y, and Zr. The in situ analyses avoid the problem of contamination of the garnet phase by trace element-rich accessory minerals encountered in traditional bulk phenocryst/matrix partitioning studies. The partitioning pattern for the rare earth elements (REEs, excluding Eu) is smooth and rises steeply from the light to the heavy REEs with no sharp kinks or changes in slope, unlike patterns for garnet /silicic liquid REE partitioning determined by bulk methods. This difference suggests that the previous determinations by bulk methods are in error, having suffered from contamination of the phenocryst separates. ?? 1992.

  8. Thermodynamic Calibration of Cr-Al Exchange Equilibria for Garnet and Spinel

    NASA Astrophysics Data System (ADS)

    Hamecher, E. A.; Antoshechkina, P. M.; Ghiorso, M. S.; Asimow, P. D.

    2009-12-01

    xMELTS is a new thermodynamic model of igneous phase equilibria (Ghiorso et al., 2007, Eos 88, V31C-0608) that extends MELTS (Ghiorso and Sack, 1995, CMP 119, 197-212) and pMELTS (Ghiorso et al., 2002, G3, 10.1029/2001GC000217) to a broader range of bulk compositions and to pressure and temperature conditions spanning from the shallow crust to the top of Earth’s lower mantle. To complete xMELTS, comprehensive garnet and pyroxene solid solution models that include Cr and other minor components must be developed. Garnet is an important phase involved in partial melting of the upper mantle because it controls partitioning of major and minor elements at pressures greater than 3 GPa. Chromium is a minor but significant component of mantle rocks as its presence increases the stability of spinel relative to plagioclase at low pressure and to garnet at high pressure. Thermodynamic models incorporating Cr into garnet solid solutions have been absent from the MELTS packages, motivating simulations for Cr-free bulk compositions and preventing accurate modeling of the spinel-garnet phase transition. The extension of the garnet model to include energetics of mixing on the Y-site is the first step in a planned calibration that will also include the majorite component needed for transition zone garnets. Initially, standard state properties and phase equilibria experiments for a Cr-bearing garnet endmember were compiled. Internally consistent thermodynamic properties of the endmember species were found by examination of reversal experiments on pure systems. We used the reversal experiments of Klemme (2004, Lithos 77, 639-646) to fix the enthalpy and entropy of knorringite (Mg3Cr2Si3O12), but were unable to fit the reversals using the standard state values given by Klemme and instead re-optimized these parameters. Although a Cr-bearing garnet model is included in the PERPLEX package (Connolly, 1990, AJS 290, 666-718; Connolly and Petrini, 2002, J.Met.Pet. 20, 697-708), the Y-site exchange in that model is treated as an ideal solution (Klemme et al., 2009, Lithos, 10.1016/j.lithos.2009.05.007). We have found such an approximation to be inconsistent with the database of experiments with coexisting garnet-spinel pairs, and instead have calibrated a non-ideal model of Cr-Al exchange on the Y-site. Indeed, we found that the data support an asymmetric pressure- and temperature-dependent regular-solution model. Application of this model improves the energy residual sum of squares by at least an order of magnitude relative to a pressure- and temperature-independent model. Cross-site terms were not required, and for the moment we have retained the X-site parameters of Berman and Koziol (1991, AM 76, 1223-1231). In testing this calibration, we discovered that the current MELTS model places the garnet-spinel transition in lherzolite at an anomalously low pressure of ~1.7 GPa. This first appeared when an earlier error in the multiplicity of the X-site was corrected (Smith and Asimow, 2005, G3, 10.1029/2004GC000816). The new error appears to be a complex result of the calibration of non-quadrilateral clinopyroxene properties, and should be corrected in the near future by the coupled recalibration of garnet and pyroxene models.

  9. Diamond and coesite discovered in Saxony-type granulite: solution to the Variscan garnet peridotite enigma?

    NASA Astrophysics Data System (ADS)

    O'Brien, P. J.; Kotkova, J.; Ziemann, M. A.

    2010-12-01

    A characteristic feature of the European Variscides is the presence of units containing felsic HP granulite (orthopyroxene-free, ternary feldspar +quartz +garnet +kyanite rocks of granitic composition) and numerous bodies of garnet peridotite. Several studies have demonstrated the formation conditions of the garnet peridotite and/or enclosed pyroxenite or eclogite layers to lie deep within the coesite and even diamond stability fields. These metamorphic conditions are nothing special for such mantle rocks but their presence in slices of high-grade continental crust requires explanation. Do the peridotites represent metastable segments of deeper mantle transported to shallower levels, by processes such as mantle diapirism, before being incorporated in thickened crustal wedges at pressures below that required for coesite stability? Or, alternatively, were the mantle slices captured by deep subduction of continental crust to coesite- and even diamond-forming depths? Microdiamonds occur in Variscan units of the Central Erzgebirge, Germany, at the Saidenbachtal reservoir in garnet-phengite gneiss: a very unusual and rare rock type that has even been given the special name Saidenbachite. At the same location, coesite has been identified in rare eclogites. Elsewhere in the Bohemian Massif only polycrystalline quartz aggregates proposed to be pseudomorphing former coesite have so far been reported and suggested ultrahigh pressure conditions for unusual grossular-rich garnet-bearing gneisses in Poland and Mg-rich garnet+orthopyroxene rocks from Moravia are again for exotic rocks of very minor extent. We have discovered microdiamonds and coesite in situ in HP granulites of the N Bohemian crystalline basement. Diamond, identified by micro-Raman, was found as single 5-30 ?m diameter inclusions in garnet, kyanite and zircon as well as in multi-grain clusters within garnet. Grains range from well-formed octahedra in kyanite to ragged, sub-rounded crystals in places forming clusters of different size grains in garnet. In kyanite the micro-diamond occurs with only very minor associated graphite whereas in garnet the grains commonly appear in multi-phase assemblages with variable proportions of the phases graphite, apatite, rutile, quartz and carbonate minerals (dolomite, aragonite). Graphite aggregates and radiating polishing scratches visible by reflected light microscopy aided prospecting for diamond-bearing samples. Coesite was confirmed in one sample as an inclusion in kyanite that itself was totally enclosed in garnet. Our confirmation of UHP conditions in both felsic kyanite-bearing and intermediate clinopyroxene-bearing granulites is of critical importance to understanding the tectono-metamorphic evolution of the Variscan belt as these common rock types are found throughout the orogen. The major implication is that the garnet peridotite bodies commonly associated with these granulites, undoubtedly HP and UHP rocks, became interdigitated with deeply subducted continental crust at UHP conditions rather than being tectonically emplaced at shallower levels as proposed in several recent models.

  10. A field and theoretical analysis of garnet+chlorite+chloritoid+biotite assemblages from the tri-state (MA, CT, NY) area, USA

    Microsoft Academic Search

    Ping Wang; Frank S. Spear

    1991-01-01

    The prograde evolution of minerals in metapelites of a Barrovian sequence from the tri-state area (Massachusetts, Connecticut, New York) of the Taconic Range involves assemblages with garnet (Ga), chlorite (Ch), chloritoid (Ct), biotite (Bi) and staurolite (St). Detailed petrologic observations, mineral compositions and chemical zoning in garnet show: (1) garnet high in Mn and Fe but low in Mg is

  11. Garnet cannibalism provides clues to extensive hydration of lower crustal fragments in a subduction channel (Sesia Zone, Northwestern Alps)

    NASA Astrophysics Data System (ADS)

    Giuntoli, Francesco; Lanari, Pierre; Engi, Martin

    2015-04-01

    The extent to which granulites are transformed to eclogites is thought to impose critical limits on the subduction of continental lower crust. Although it is seldom possible to document such densification processes in detail, the transformation is believed to depend on fluid access and deformation. Remarkably complex garnet porphyroblasts are widespread in eclogite facies micaschists in central parts of the Sesia Zone (Western Italian Alps). They occur in polydeformed samples in assemblages involving phengite+quartz+rutile ±paragonite, Na-amphibole, Na-pyroxene, chloritoid. Detailed study of textural and compositional types reveals a rich inventory of growth and partial resorption zones in garnet. These reflect several stages of the polycyclic metamorphic evolution. A most critical observation is that the relict garnet cores indicate growth at 900 °C and 0.9 GPa. This part of the Eclogitic Micaschist Complex thus derived from granulite facies metapelites of Permian age. These dry rocks must have been extensively hydrated during Cretaceous subduction, and garnet records the conditions of these processes. Garnet from micaschist containing rutile, epidote, paragonite and phengite were investigated in detail. Two types of garnet crystals are found in many thin sections: mm-size porphyroclasts and smaller atoll garnets, some 100 µm in diameter. X-ray maps of the porphyroclasts show complex zoning in garnet: a late Paleozoic HT-LP porphyroclastic core is overgrown by several layers of HP-LT Alpine garnet, these show evidence of growth at the expense of earlier garnet generations. Textures indicate 1-2 stages of resorption, with garnet cores that were fractured and then sealed by garnet veins, rimmed by multiple Alpine overgrowth rims with lobate edges. Garnet rim 1 forms peninsula and embayment structures at the expense of the core. Rim 2 surrounds rim 1, both internally and externally, and seems to have grown mainly at the expense of the core. Rim 3 grew mainly at the expense of earlier Alpine rims. In the same samples that show porphyroclastic garnet, atoll garnet occurs, filled with quartz, and the same Alpine overgrowth zones are observed in both types of garnet. Similar features of garnet zoning are present in various lithotypes, allowing the evolution of this continental domain during subduction to be traced. Modeling the different garnet growth zones is challenging, each growth step demanding an estimate the effective bulk composition. According to the XRF analyses of the bulk sample, the core is found to have formed at 900°C, 0.9 GPa. Based on effective bulk compositions, the successive Alpine rims are found to reflect an increase from 600°C, 1.55-1.60 GPa for rim 1 to 630-640°C, 1.9-2.0 GPa for rim 2. Allanite crystals contain inclusions of Alpine garnet; in situ geochronology (U-Th-Pb by LA-ICP-MS) on allanite yields a (minimum) age of ~69 Ma for the main growth of garnet. In summary, the textures and mineral compositions clearly reflect reactive interaction of major amounts of hydrous fluids with dry protoliths. The source of these fluids responsible for converting granulites back to micaschists at eclogite facies conditions within the Sesia subduction channel is being investigated.

  12. Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

    PubMed

    Maeda, Y

    1994-01-10

    Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection. PMID:20862016

  13. The origin of garnet in the anorthosite-charnockite suite of the Adirondacks

    Microsoft Academic Search

    James M. McLelland; Philip R. Whitney

    1977-01-01

    Detailed analysis of textural and chemical criteria in rocks of the anorthosite-charnockite suite of the Adirondack Highlands suggests that development of garnet in silica-saturated rocks of the suite occurs according to the reaction: \\u000a$$\\\\begin{gathered} {\\\\text{Anorthite}} {\\\\text{Orthopyroxene}} {\\\\text{Quartz}} \\\\hfill \\\\\\\\ {\\\\text{2CaAl}}_{\\\\text{2}} {\\\\text{Si}}_{\\\\text{2}} {\\\\text{O}}_{\\\\text{8}} + (6 - \\\\alpha )({\\\\text{Fe,Mg}}){\\\\text{SiO}}_{\\\\text{3}} + \\\\alpha {\\\\text{Fe - Oxide + (}}\\\\alpha {\\\\text{ - 2)SiO}}_{\\\\text{2}} \\\\hfill \\\\\\\\ {\\\\text{Garnet}}

  14. Dating high-grade metamorphism: constraints from zircon and garnet REE compositions

    NASA Astrophysics Data System (ADS)

    Whitehouse, M. J.; Platt, J. P.

    2001-12-01

    We present high spatial resolution ion microprobe REE analyses of zircon and garnet from pelitic granulite adjacent to the Ronda peridotite, Betic Cordillera, southern Spain. The zircons exhibit polyphase growth, with thick structureless (in cathodoluminescence) overgrowths over detrital cores. These overgrowths yield a U-Pb age of 21.3 +/- 0.3 Ma [1, unpublished data] which we intepret as dating an episode of zircon growth during the Alpine orogeny. REE analyses of the dated portions of these zircons reveal profound differences between cores and rims. Cores show patterns typical of magmatic zircon (steep upward slopes from La to Lu with marked positive Ce anomaly), while the overgrowths are characterised by flat or even negatively sloping HREE profiles (Gd - Lu). Garnet, which occupies ca. 30 % by volume of the rock, is the most likely phase to host the HREEs in the rock and has been the subject of further ion-microprobe REE, textural and trace element investigations. The garnets are themselves zoned, with dominant central regions that are relatively free of inclusions overgrown by inclusion-rich, more calcic rims. Inclusions of kyanite +rutile in the central regions and sillimanite +ilmenite in the rims suggests that the garnets grew during decompression, and the Ca-enrichment in the rims suggests that their growth coincided with the initiation of partial melting. The presence of rimmed zircons only in the garnet rims and the matrix further suggests that the zircons also grew during this late decompressional history. An REE traverse of the garnet from core to rim reveals marked HREE depletion in the rims relative to the cores which we suggest is consistent with the textural evidence and probably results from early garnet core growth strongly depleting the HREEs available to subsequent growth. This mechanism can also be invoked to explain depletion in the zircon rims and more closely ties their formation to this stage of garnet growth. We therefore interpret the 21.3 +/- 0.3 Ma U-Pb age from the zircon rims as dating a point on the decompressional path rather than peak metamorphic pressure. [1] Platt, J.P. and Whitehouse, M.J. (1999) EPSL 171, 591-605.

  15. Internal Microstructure and Breakdown of Garnet from Moldanubian Granulites (Gföhl Unit, Dunkelsteinerwald, Lower Austria)

    NASA Astrophysics Data System (ADS)

    Bourgin, Nathalie; Abart, Rainer; Petrakakis, Konstantin

    2014-05-01

    Symplectites in some conspicuous granulite facies rocks from the Moldanubian Gföhl Unit in Lower Austria show an unusual bulk composition with very high Mg, Ca contents and 14 mole% normative corundum. It contains garnet (XPyr>0,5), clinopyroxene (XMg: 14 mole%; XCaTs: 0,3), pargasitic hornblende (XMg: 17 mole%), and plagioclase (XAn>0,8). The primary microstructure is granular, medium-grained and well equilibrated. Clinopyroxene often shows exsolution lamellae and inclusions of amphibole and plagioclase. Garnets of about 2-3cm size are common. Often they are resorbed and therefore significantly smaller. The large garnets display numerous inclusions, e.g. of kyanite. The garnets show internal deformation domains. The lattice orientations of the different domains show displacements around a common rotation axis approximately parallel to [211]. This points to incipient polygonalization of garnet during crystal plastic deformation at obviously high strain rates under high grade metamorphic conditions. Along garnet margins and within cracks, various replacement symplectites were formed comprising distinct assemblages among orthopyroxen, spinel, anorthite, Al-rich amphibole, tschermakitic diopside, sapphirine and corundum. Symplectite formation was induced by decompression feature. The last peak metamorphic conditions of the Gföhl Unit has been estimated in previous studies with pressures and temperatures around resp. 8-11 kbar and 700-800°C. The rocks then experienced isothermal decompression followed by isobaric cooling around 5-6 kbar (e.g. Petrakakis 1997). The temperature during the formation of the symplectites has been estimated by garnet-orthopyroxene thermometry and resulted in values of approx. 700°C for the pressure-range of 5-6 kbar, indicating essentially isothermal decompression. The rims of breaking down garnets adjacent to Opx+Spl+Pl-symplectite show diffusional zoning patterns allowing geospeedometry modelling. This zoning is continuous displaying increasing Fe and decreasing Mg towards the rim. Diffusion modelling gives a time interval for symplectite formation of about 1000 years, dating thus an instantaneous decompression event within the geological time frame. Preservation of the delicate symplectite microstructures and the lack of penetrative deformation are consistent with isobaric cooling at 5-6 kbar suggested earlier.

  16. Deep levels in gallium arsenide devices

    NASA Astrophysics Data System (ADS)

    Chen, Den Fu

    Deep-level traps can cause problems in gallium arsenide (GaAs) devices. Investigating deep level impurities in GaAs devices is the purpose of this research. Variable temperature current-voltage and capacitance-voltage measurements are used to characterize the devices. The devices are also investigated with deep level transient spectroscopy (DLTS) using lock-in amplifier DLTS and Fourier transform DLTS to identify the deep-level traps. The most important native defect in GaAs, EL2, is the main deep level impurity investigated and compared with the results of other researchers. Instead of a unique value of energy level and capture cross section, the deep level signature spreads over a wide range of values. Moreover, a strong correlation exists between the energy levels and the capture cross sections of the deep levels. To understand this correlation of energy level with capture cross section, a number of effects on the trap signature have been studied, including series resistance, leakage current, applied voltage (electric field), and various DLTS parameters. Numerical multiple-exponential fitting of the capacitance transients was used to extract the time constants of the transients. The measurement shows that the series resistance is not sufficiently significant to affect the DLTS result. The effects of reverse bias and filling pulse voltage appear significant in some cases. Data also show that there is an interaction between the pulse width and the window time on the correlation. The delay time during the early part of the capacitance transient in DLTS measurements can cause significant deviations of the extracted time constants. Fourier transform DLTS simulation shows that the signature of a deep level can vary significantly due to incorrect delay time consideration leading to a strong correlation between energy level and capture cross section.

  17. Hepatic tumors: magnetization transfer MR imaging with gadolinium enhancement.

    PubMed

    Onaya, H; Yoshioka, H; Itai, Y; Niitsu, M; Anno, I; Okumura, T

    1995-01-01

    Thirty patients with 15 hepatocellular carcinomas, 10 metastases, four hemangiomas, and one cholangiocarcinoma underwent magnetic resonance imaging at 1.5 T with T1-weighted, T2-weighted spin-echo (SE) images, gradient-echo (GRE) magnetization transfer (MT) images, and gadolinium-enhanced T1-weighted SE and MT-GRE images. The MT effect and lesion-liver contrast-to-noise ratio (C/N) were calculated and visual assessment (qualitative analysis) performed for unenhanced and enhanced MT-GRE images and enhanced T1-weighted SE images. The C/N values for hepatic adenocarcinomas (seven metastases and one cholangiocarcinoma) and hemangiomas were larger for enhanced MT-GRE images (adenocarcinoma, 8.4 +/- 2.3 [P < .01]; hemangioma 24 +/- 2.1 [P < .05]) than for enhanced GRE images (5.0 +/- 1.9 and 18 +/- 2.7, respectively). These enhancing tumors had the highest scores in the qualitative analysis. Enhanced MT-GRE images showed no advantage for depiction of hepatocellular carcinomas relative to the other images. PMID:7633103

  18. Laser Demagnetization Dynamics in Gadolinium from Time Resolved Photoemission

    NASA Astrophysics Data System (ADS)

    Bowlan, John; Frietsch, Björn; Teichmann, Martin; Carley, Robert; Weinelt, Martin

    2014-03-01

    The field of ultrafast magnetization dynamics has seen rapid progress in recent years and has the potential to enable magnetic data storage systems orders of magnitude faster than those based on conventional read/write heads. The dynamics of laser demagnetization in ferromagnetic Gadolinium depend on the transfer of energy and angular momentum between the metallic valence electrons and the core-like 4 f electrons. Angle-Resolved Photoemission (ARPES) with femtosecond XUV laser pulses produced by high harmonic generation enables the direct measurement of the electronic band structure on a sub-picosecond time scale in a ``tabletop'' setup. Photoemission allows the magnetization dynamics of the valence and 4 f bands to be tracked independently of one another. Thus, time-resolved photoemission is an alternative to experimental methods such as surface magnetic second harmonic generation (MSHG), the magneto-optical Kerr effect (MOKE), and x-ray magnetic circular dichroism (XMCD). We applied this technique to study Gd(0001) films grown epitaxially on a W crystal. We find that the valence electrons demagnetize on a fs time scale, while the 4f electrons respond more slowly.

  19. Thermal decomposition and recovery behaviors of layered gadolinium hydroxychloride.

    PubMed

    Lee, Seoung-Soo; Lee, Byung-Il; Kim, Seung-joo; Byeon, Song-Ho; Kang, Jun-Kun

    2012-10-01

    The thermal behavior of gadolinium hydroxychloride (Gd(2)(OH)(5)Cl·nH(2)O, LGdH) has been closely studied to provide the important factors that should be considered for its high temperature applications. Combined analyses of thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS) showed that, under atmospheric air with a considerable amount of water, the decomposition of LGdH to Gd(2)O(3) is completed at 1050 °C. However, in either dry air or Ar gas, the transformation continued up to around 1300 °C. Thus, the thermal decomposition of LGdH was more influenced by H(2)O than by O(2). FT-IR spectra and X-ray diffraction (XRD) patterns were used to study LGdHs calcined at high temperatures (up to at least 600 °C). Calcined LGdH's ability to intercalate anions into the interlayer space could be recovered by the reconstruction of intralayer structure through rehydration and rehydroxylation. These processes were significantly accelerated at elevated temperatures. The recovery behavior of LGdH was examined in different anionic solutions at different temperatures. PMID:22963192

  20. Gadolinium oxide nanoparticles as potential multimodal imaging and therapeutic agents.

    PubMed

    Kim, Tae Jeong; Chae, Kwon Seok; Chang, Yongmin; Lee, Gang Ho

    2013-01-01

    Potentials of hydrophilic and biocompatible ligand coated gadolinium oxide nanoparticles as multimodal imaging agents, drug carriers, and therapeutic agents are reviewed. First of all, they can be used as advanced T1 magnetic resonance imaging (MRI) contrast agents because they have r1 larger than those of Gd(III)-chelates due to a high density of Gd(III) per nanoparticle. They can be further functionalized by conjugating other imaging agents such as fluorescent imaging (FI), X-ray computed tomography (CT), positron emission tomography (PET), and single photon emission tomography (SPECT) agents. They can be also useful for drug carriers through morphology modifications. They themselves are also potential CT and ultrasound imaging (USI) contrast and thermal neutron capture therapeutic (NCT) agents, which are superior to commercial iodine compounds, air-filled albumin microspheres, and boron ((10)B) compounds, respectively. They, when conjugated with targeting agents such as antibodies and peptides, will provide enhanced images and be also very useful for diagnosis and therapy of diseases (so called theragnosis). PMID:23432005

  1. Infrared spectra of iron phosphate glasses with gadolinium oxide

    NASA Astrophysics Data System (ADS)

    Lai, Yuanming; Liang, Xiaofeng; Yin, Guangfu; Yang, Shiyuan; Wang, Junxia; Zhu, Haixiang; Yu, Hongtao

    2011-10-01

    The structure of xGd 2O 3sbnd (40 - x)Fe 2O 3sbnd 60P 2O 5 (0 ? x ? 12 mol%) glasses have been investigated using Fourier transform infrared spectroscopy (FT-IR). The X-ray diffraction (XRD) and scanning electron microscope (SEM) for the samples containing 9 mol% Gd 2O 3 show the presence of a unique crystalline phase, GdPO 4, embedded in an amorphous matrix. These results suggest that the solubility of gadolinium in these iron phosphate melts is less than 9 mol% Gd 2O 3. FTIR data suggest that the replacement of up to 6 mol% Fe 2O 3 by Gd 2O 3 in the 40Fe 2O 3sbnd 60P 2O 5 (mol%) glass does not produce any fundamental change in structure of the phosphate network, which consists of predominantly pyrophosphate groups with a small proportion of metaphosphate and orthophosphate groups. This suggests that Gd is substituted into Fe sites in phosphate network. From all these considerations we can conclude that Gd 2O 3 enters in the structure of studied glasses as a network modifier.

  2. Stimulation of fibroblast proliferation by insoluble gadolinium salts.

    PubMed

    Bleavins, Katherine; Perone, Patricia; Naik, Madhav; Rehman, Muneeb; Aslam, Muhammad N; Dame, Michael K; Meshinchi, Sasha; Bhagavathula, Narasimharao; Varani, James

    2012-02-01

    The purpose of this study was to assess insoluble salts containing gadolinium (Gd(3+)) for effects on human dermal fibroblasts. Responses to insoluble Gd(3+) salts were compared to responses seen with Gd(3+) solubilized with organic chelators, as in the Gd(3+)-based contrast agents (GBCAs) used for magnetic resonance imaging. Insoluble particles of either Gd(3+) phosphate or Gd(3+) carbonate rapidly attached to the fibroblast cell surface and stimulated proliferation. Growth was observed at Gd(3+) concentrations between 12.5 and 125 ?M, with toxicity at higher concentrations. Such a narrow window did not characterize GBCA stimulation. Proliferation induced by insoluble Gd(3+) salts was inhibited in the presence of antagonists of mitogen-activated protein kinase and phosphatidylinositol 3-kinase signaling pathways (similar to chelated Gd(3+)) but was not blocked by an antibody to the platelet-derived growth factor receptor (different from chelated Gd(3+)). Finally, high concentrations of the insoluble Gd(3+) salts failed to prevent fibroblast lysis under low-Ca(2+) conditions, while similar concentrations of chelated Gd(3+) were effective. In conclusion, while insoluble Gd(3+) salts are capable of stimulating fibroblast proliferation, one should be cautious in assuming that GBCA dechelation must occur in vivo to produce the profibrotic changes seen in association with GBCA exposure in the subset of renal failure patients that develop nephrogenic systemic fibrosis. PMID:21882070

  3. A fertile harzburgite-garnet lherzolite transition: possible inferences for the roles of strain and metasomatism in upper mantle peridotites

    NASA Astrophysics Data System (ADS)

    Dawson, J. B.

    2004-09-01

    Porphyroclastic enstatite in a garnet lherzolite xenolith from the Monastery Mine kimberlite, South Africa, has exsolved pyrope garnet, Cr-diopside and Al-chromite, and the specimen is interpreted as representing a transition from fertile harzburgite, (containing high Ca-Al-Cr enstatite) to granular garnet lherzolite. Although the exsolved phases occur in morphologically different forms (fine and coarse lamellae; equant, ripened grains), indicating textural disequilibrium, the exsolved grains are very constant in composition, indicating chemical equilibrium. Theoretically, the exsolution could have been due to a fall in temperature, but the close association of exsolution and deformation of the host enstatite suggests that exsolution was also aided by straining of the enstatite lattice. The phase compositions can be broadly matched with those in other mantle peridotites, except that all phases are characterised by a virtual absence of Ti. In the garnet and diopside Ti, Co, Zr and most of the REE are lower than in published analyses of garnet and diopside in both granular and sheared garnet lherzolites from Southern African kimberlites, and diopside/garnet partitioning for Sr and the REE is higher. Comparison with the trace element chemistry of an enstatite from a fertile harzburgite indicates that, except for Nb, the trace element content and distribution found in the Monastery phases could arise by isochemical exsolution from such an enstatite. On the assumption that (a) the Monastery specimen represents a transition from harzburgite to garnet lherzolite, and (b) many garnet lherzolites are of exsolution origin (as suggested by their modal compositions), the inference is that most garnet lherzolites, and not just the sheared variety, have been subject to varying degrees of Ti, Zr, Sr and REE metasomatism.

  4. Nucleation mechanism of gallium-assisted molecular beam epitaxy growth of gallium arsenide nanowires

    SciTech Connect

    Fontcuberta i Morral, A.; Colombo, C.; Abstreiter, G.; Arbiol, J.; Morante, J. R. [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, 85748 Garching (Germany); TEM-MAT, Serveis Cientificotecnics, Universitat de Barcelona, CAT, E-08080 Barcelona (Spain); EME/CeRMAE/IN2UB, Departament d'Electronica, Universitat de Barcelona, C/Marti i Franques 1, CAT, E-08080 Barcelona (Spain)

    2008-02-11

    Molecular beam epitaxy Ga-assisted synthesis of GaAs nanowires is demonstrated. The nucleation and growth are seen to be related to the presence of a SiO{sub 2} layer previously deposited on the GaAs wafer. The interaction of the reactive gallium with the SiO{sub 2} pinholes induces the formation of nanocraters, found to be the key for the nucleation of the nanowires. With SiO{sub 2} thicknesses up to 30 nm, nanocraters reach the underlying substrate, resulting into a preferential growth orientation of the nanowires. Possibly related to the formation of nanocraters, we observe an incubation period of 258 s before the nanowires growth is initiated.

  5. Synthesis of gallium nitride nanostructures by nitridation of electrochemically deposited gallium oxide on silicon substrate.

    PubMed

    Ghazali, Norizzawati Mohd; Yasui, Kanji; Hashim, Abdul Manaf

    2014-01-01

    Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga2O3) through the utilization of a so-called ammoniating process. Ga2O3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm(2) using a mixture of Ga2O3, HCl, NH4OH and H2O for 2 h. Then, the deposited Ga2O3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga2O3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga2O3 structure was detected, suggesting a complete transformation of Ga2O3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga2O3 to generate gaseous Ga2O increase with temperature. The growth mechanism for the transformation of Ga2O3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga2O3. A significant change of morphological structures takes place after a complete transformation of Ga2O3 to GaN where the original nanorod structures of Ga2O3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si. PMID:25593562

  6. Synthesis of gallium nitride nanostructures by nitridation of electrochemically deposited gallium oxide on silicon substrate

    NASA Astrophysics Data System (ADS)

    Ghazali, Norizzawati Mohd; Yasui, Kanji; Hashim, Abdul Manaf

    2014-12-01

    Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga2O3) through the utilization of a so-called ammoniating process. Ga2O3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm2 using a mixture of Ga2O3, HCl, NH4OH and H2O for 2 h. Then, the deposited Ga2O3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga2O3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga2O3 structure was detected, suggesting a complete transformation of Ga2O3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga2O3 to generate gaseous Ga2O increase with temperature. The growth mechanism for the transformation of Ga2O3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga2O3. A significant change of morphological structures takes place after a complete transformation of Ga2O3 to GaN where the original nanorod structures of Ga2O3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si.

  7. Visible light electroluminescent diodes of indium-gallium phosphide

    NASA Technical Reports Server (NTRS)

    Clough, R.; Richman, D.; Tietjen, J.

    1970-01-01

    Vapor deposition and acceptor impurity diffusion techniques are used to prepare indium-gallium phosphide junctions. Certain problems in preparation are overcome by altering gas flow conditions and by increasing the concentration of phosphine in the gas. A general formula is given for the alloy's composition.

  8. CCMR: Bulk GaN Growth by Gallium Vapor Transport

    NSDL National Science Digital Library

    Spinelli, Joseph

    2005-08-17

    Gallium nitride (GaN) is currently an extremely popular material used in the fabrication of many optoelectronic and electronic devices such as LEDs and LDs. Since gallium nitride is a direct band gap material there is a much more efficient output of energy. Unlike many other semiconductor materials such as silicon, which will emit a large portion of energy in the form of heat, gallium nitride emits mostly photons. The high electron mobility of the GaN results in the possibility of fabrication high frequency devices, high power devices which can be used for applications such as CD or DVD writing. The influence of high frequency or low wavelength lasers aids in the writing process by allowing more information to be stored in a smaller region of space. However the process required to fabricate high quality GaN crystals is still very costly and slow, thus holding industry back from fabricating mass quantities of GaN commercially. Bulk GaN Growth by Gallium Vapor Transport was attempted

  9. Defect levels in indium and gallium doped zinc selenide

    Microsoft Academic Search

    A. A. Qidwai; J. Woods

    1982-01-01

    Indium and gallium dopants in ZnSe display unusual properties in that although they act as shallow donors in low concentration, complex compensation effects appear to occur at high concentration, so that the resistivity increases with increasing impurity content. In order to investigate these effects, the techniques of transient photocapacitance and transient photocurrent have been used to study the incidence of

  10. Temperature Dependence of Recombination Lifetime in Gallium Arsenide Electroluminescent Diodes

    Microsoft Academic Search

    Takao Nakano; Taiji Oku

    1967-01-01

    The temperature dependence of the radiative recombination lifetime, current dependence of the externally radiated light output, and the photon energy of the radiated light in gallium arsenide electroluminescent diodes were investigated in the temperature range from 345°K to 77°K. The radiative recombination lifetime was derived by using the Shockley-Read statistics. Experimental results were analysed by this model and it was

  11. High purity liquid phase epitaxial gallium arsenide nuclear radiation detector

    Microsoft Academic Search

    Dimitri Alexiev; K. S. A. Butcher

    1992-01-01

    Surface barrier radiation detector made from high purity liquid phase epitaxial gallium arsenide wafers have been operated as X- and gamma-ray detectors at various operating temperatures. Low energy isotopes are resolved including 241Am at 40°C and the higher gamma energies of 235U at -80°C.

  12. Growth and characterization of novel gate dielectrics for gallium nitride

    Microsoft Academic Search

    Andrea H. Onstine

    2004-01-01

    Novel crystalline dielectric materials for gate application on gallium nitride were studied. These dielectric materials must operate at high temperatures and under high power loads. To meet these needs, the selected dielectric materials must be thermally stable to temperatures above 1000°C for device fabrication, must be chemically stable to prevent diffusion into the semiconductor, and must have a low defect

  13. THE MAGNETOCRYSTALLINE ANISOTROPY OF GALLIUM AND ALUMINIUM SUBSTITUTED MAGNETITE

    E-print Network

    Paris-Sud XI, Université de

    409 THE MAGNETOCRYSTALLINE ANISOTROPY OF GALLIUM AND ALUMINIUM SUBSTITUTED MAGNETITE By R. F of the magnetocrystalline anisotropy in magnetite (Fe3O4) as this shows a rather anomalous variation with temperature constante d'anisotropie K1 ont été mesurées de 120 °K à 400 °K par la méthode de torsion, pour sept cristaux

  14. A molecular dynamics investigation of low temperature gallium arsenide

    Microsoft Academic Search

    Joseph Irwin Landman

    1997-01-01

    An theoretical investigation of point defect and defect complexes in low temperature Gallium Arsenide (LT GaAs) has been undertaken, specifically targeting the question of the location of excess Arsenic storage in this non-stoichiometric bulk material. Molecular dynamics techniques has been used to form low energy defect configurations for study, specifically those defects which allow for an excess of Arsenic. The

  15. Discovery of Gallium, Germanium, Lutetium, and Hafnium Isotopes

    E-print Network

    Gross, J L

    2011-01-01

    Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  16. Quartzhomeotypic gallium orthophosphate: A new high-tech piezoelectric crystal

    Microsoft Academic Search

    P. W. Krempl

    1997-01-01

    Piezoelectric crystals belong to the most important functional materials for the electronic and electromechanic industries. Many future technologies will demand for materials having the excellent properties owned by quartz, but higher electromechanical coupling and high thermal stability in their properties up to temperatures above 600°C. It has been demonstrated, that single crystals of quartzhomeotypic gallium orthophosphate (GaPO4) can meet all

  17. GALLIUM ARSENIDE, INDIUM PHOSPHIDE. CHEMICAL VAPOR DEPOSITION AND PHOTOLUMINESCENCE PROPERTIES

    E-print Network

    Boyer, Edmond

    783 GALLIUM ARSENIDE, INDIUM PHOSPHIDE. CHEMICAL VAPOR DEPOSITION AND PHOTOLUMINESCENCE PROPERTIES production and its good control of growth and impurity incorporation, vapor phase epitaxy seems to be more the near band gap photoluminescence (PL) of vapor grown layers needs to be improved. Since the luminescence

  18. Abnormal gallium scintigraphy in pulmonary alveolar proteinosis (PAP)

    SciTech Connect

    Yeh, S.D.; White, D.A.; Stover-Pepe, D.E.; Caravelli, J.F.; Van Uitert, C.; Benua, R.S.

    1987-04-01

    A patient with medulloblastoma of the cerebellum developed dyspnea and hypoxemia. Pulmonary function tests showed decreased lung volume and diffusing capacity, while the chest radiographs initially showed only mild interstitial infiltrates. Repeated gallium scans showed diffuse lung uptake and diagnosis of pulmonary alveolar proteinosis was made by open lung biopsy.

  19. Compatibility of ITER candidate materials with static gallium

    SciTech Connect

    Luebbers, P.R.; Chopra, O.K. [Argonne National Lab., IL (United States). Energy Technology Div.

    1995-09-01

    Corrosion tests have been conducted to determine the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor (ITER) first wall/blanket systems, e.g., Type 316 stainless steel (SS), Inconel 625, and Nb-5 Mo-1 Zr. The results indicate that Type 316 SS is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At 400 C, corrosion rates for Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy are {approx} 4.0, 0.5, and 0.03 mm/yr, respectively. Iron, nickel, and chromium react rapidly with gallium. Iron shows greater corrosion than nickel at 400 C ({ge} 88 and 18 mm/yr, respectively). The present study indicates that at temperatures up to 400 C, corrosion occurs primarily by dissolution and is accompanied by formation of metal/gallium intermetallic compounds. The growth of intermetallic compounds may control the overall rate of corrosion.

  20. Multistage metasomatism in lithospheric mantle beneath V. Grib pipe (Arkhangelsk diamondiferous province, Russia): evidence from REE patterns in garnet xenocrysts.

    NASA Astrophysics Data System (ADS)

    Shchukina, Elena; Alexei, Agashev; Nikolai, Pokhilenko

    2015-04-01

    150 garnet xenocrysts from V. Grib kimberlite pipe were analyzed for major and trace elements compositions. 70 % of garnet belong to lherzolite field; 14 % - megacrysts and pyroxenites; 11 % - eclogites; 4 % - harzburgite; 1 % (1- wehrlite defined by Sobolev (1973). Harzburgite garnets: sinusoidal REE patterns Smn/Ern > 5 (5.2 - 19.8). low Y (0.5 - 3.9 ppm), Zr (1.1 - 44.6 ppm), Ti (54 - 1322 ppm). Wehrlite garnetd: close to sinusoidal REE patterns, Smn/Ern - 1.8. Megacrysts and pyroxenites garnets: normal REE patterns Smn/Ern < 1 (0.2 - 0.6), high TiO2 (0.9 - 1.3 wt %). Lherzolite garnets 70 % show four groups of REE patterns similar to peridotite xenoliths (Shchukina et al., 2013, 2015). 1-st contains MREE at ?1 level, Sm/Ern - 0.03, La/Ybn - 0.002. increasing La -Yb range, low Y, Zr, Ti indicating residual nature. 2-nd: MREE at 2 - 13 chondrite units, Smn/Ern (0.16 - 0.98), La/Ybn - 0.001 - 0.040 and flat pattern from MREE to HREE. 3-rd -MREE at 5 - 14 chondrite units, Sm/Ern > 1 (1.05 - 4.81) La/Ybn - 0.010-0.051 increasing an hump at MREE decreasing to HREE. 4-th: sinusoidal REE, Sm/Ern 4.2 - 27.2. and harzburgite Y, Zr, Ti . Average Cr2O3 content increases from 2-nd to the 3-rd group (3.3 to 5.7 wt%) and 4th (7.9 wt %). Average Y/Zr decreases from 2-nd (0.6) to 3rd (0.2) and 4th group (0.08). REE and Y, Zr, Ti indicate the metasomatic origin of garnets of 2, 3. 4 groups. Modeling of TREfor equilibrated melts and fractional crystallization 2nd group close to Turyino field basalts and 3-rd - to Izmozero field picrites of Arkhangelsk diamondiferous province (ADP). Basing on geochemical data of garnet xenocrysts and garnets and clinopyroxenes in peridotites (Shchukina et al., 2013, 2015) we suppose at least 3 stage of high-temperature metasomatic enrichment. 1st stage - is enrichment of residual garnets (found only in peridotite garnets) in LREE by the influence of carbonatite melt close to the Mela field carbonatites of ADP. REE patterns in clinopyroxenes from these peridotite samples and the geochemical modeling results show that clinopyroxenes are also in equilibrium with carbonatite melt. Formation of garnet with the sinusoidal REE pattern could also occurs during carbonatite stage of mantle metasomatism. The 2- nd stage - is formation of garnets of group 3 from the melt of composition close to Izhmozero field picrites. Garnets of group 3 are of lherzolite paragenesis on the content of CaO and Cr2O3, but their REE patterns are close to sinusoidal patterns. The final stage of mantle metasomatism is the formation of garnets of group 2 exposed to the melt of composition close to Turyino field basalts. Garnets of group 2 have low Cr2O3 that indicate the significant amounts of basaltic component in the resulting melt composition or direct crystallization from the melt in case of most low-chromium garnets and megacrysts garnets. Modeling results show that the formation of the garnets of group 2 in peridotites associated with crystallization of the clinopyroxenes. At this stage of mantle metasomatism garnets have typical major and trace element lherzolite composition.

  1. Extraction of gadolinium from high flux isotope reactor control plates. [Alternative method

    SciTech Connect

    Kohring, M.W.

    1987-04-01

    Gadolinium-153 is an important radioisotope used in the diagnosis of various bone disorders. Recent medical and technical developments in the detection and cure of osteoporosis, a bone disease affecting an estimated 50 million people, have greatly increased the demand for this isotope. The Oak Ridge National Laboratory (ORNL) has produced /sup 153/Gd since 1980 primarily through the irradiation of a natural europium-oxide powder followed by the chemical separation of the gadolinium fraction from the europium material. Due to the higher demand for /sup 153/Gd, an alternative production method to supplement this process has been investigated. This process involves the extraction of gadolinium from the europium-bearing region of highly radioactive, spent control plates used at the High Flux Isotope Reactor (HFIR) with a subsequent re-irradiation of the extracted material for the production of the /sup 153/Gd. Based on the results of experimental and calculational analyses, up to 25 grams of valuable gadolinium (greater than or equal to60% enriched in /sup 152/Gd) resides in the europium-bearing region of the HFIR control components of which 70% is recoverable. At a specific activity yield of 40 curies of /sup 153/Gd for each gram of gadolinium re-irradiated, 700 one-curie sources can be produced from each control plate assayed.

  2. Hybrid Calcium Phosphate-Polymeric Micelles Incorporating Gadolinium Chelates for Imaging-Guided Gadolinium Neutron Capture Tumor Therapy.

    PubMed

    Mi, Peng; Dewi, Novriana; Yanagie, Hironobu; Kokuryo, Daisuke; Suzuki, Minoru; Sakurai, Yoshinori; Li, Yanmin; Aoki, Ichio; Ono, Koji; Takahashi, Hiroyuki; Cabral, Horacio; Nishiyama, Nobuhiro; Kataoka, Kazunori

    2015-06-23

    Gadolinium (Gd) chelates-loaded nanocarriers have high potential for achieving magnetic resonance imaging (MRI)-guided Gd neutron capture therapy (GdNCT) of tumors. Herein, we developed calcium phosphate micelles hybridized with PEG-polyanion block copolymers, and incorporated with the clinical MRI contrast agent Gd-diethylenetriaminepentaacetic acid (Gd-DTPA/CaP). The Gd-DTPA/CaP were nontoxic to cancer cells at the concentration of 100 ?M based on Gd-DTPA, while over 50% of the cancer cells were killed by thermal neutron irradiation at this concentration. Moreover, the Gd-DTPA/CaP showed a dramatically increased accumulation of Gd-DTPA in tumors, leading to the selective contrast enhancement of tumor tissues for precise tumor location by MRI. The enhanced tumor-to-blood distribution ratio of Gd-DTPA/CaP resulted in the effective suppression of tumor growth without loss of body weight, indicating the potential of Gd-DTPA/CaP for safe cancer treatment. PMID:26033034

  3. Pair distribution function study on compression of liquid gallium

    SciTech Connect

    Luo, Shengnian [Los Alamos National Laboratory; Yu, Tony [SUNY-SB; Chen, Jiuhua [SUNY-SB; Ehm, Lars [SUNY-SB; Guo, Quanzhong [SUNY-SB; Parise, John [SUNY-SB

    2008-01-01

    Integrating a hydrothermal diamond anvil cell (HDAC) and focused high energy x-ray beam from the superconductor wiggler X17 beamline at the National Synchrotron Light Source (NSLS) at the Brookhaven National Laboratory (BNL), we have successfully collected high quality total x-ray scattering data of liquid gallium. The experiments were conducted at a pressure range from 0.1GPa up to 2GPa at ambient temperature. For the first time, pair distribution functions (PDF) for liquid gallium at high pressure were derived up to 10 {angstrom}. Liquid gallium structure has been studied by x-ray absorption (Di Cicco & Filipponi, 1993; Wei et al., 2000; Comez et al., 2001), x-ray diffraction studies (Waseda & Suzuki, 1972), and molecular dynamics simulation (Tsay, 1993; Hui et al., 2002). These previous reports have focused on the 1st nearest neighbor structure, which tells us little about the atomic arrangement outside the first shell in non- crystalline materials. This study focuses on the structure of liquid gallium and the atomic structure change due to compression. The PDF results show that the observed atomic distance of the first nearest neighbor at 2.78 {angstrom} (first G(r) peak and its shoulder at the higher Q position) is consistent with previous studies by x-ray absorption (2.76 {angstrom}, Comez et al., 2001). We have also observed that the first nearest neighbor peak position did not change with pressure increasing, while the farther peaks positions in the intermediate distance range decreased with pressure increasing. This leads to a conclusion of the possible existence of 'locally rigid units' in the liquid. With the addition of reverse Monte Carlo modeling, we have observed that the coordination number in the local rigit unit increases with pressure. The bulk modulus of liquid gallium derived from the volume compression curve at ambient temperature (300K) is 12.1(6) GPa.

  4. Self- and zinc diffusion in gallium antimonide

    SciTech Connect

    Nicols, Samuel Piers

    2002-03-26

    The technological age has in large part been driven by the applications of semiconductors, and most notably by silicon. Our lives have been thoroughly changed by devices using the broad range of semiconductor technology developed over the past forty years. Much of the technological development has its foundation in research carried out on the different semiconductors whose properties can be exploited to make transistors, lasers, and many other devices. While the technological focus has largely been on silicon, many other semiconductor systems have applications in industry and offer formidable academic challenges. Diffusion studies belong to the most basic studies in semiconductors, important from both an application as well as research standpoint. Diffusion processes govern the junctions formed for device applications. As the device dimensions are decreased and the dopant concentrations increased, keeping pace with Moore's Law, a deeper understanding of diffusion is necessary to establish and maintain the sharp dopant profiles engineered for optimal device performance. From an academic viewpoint, diffusion in semiconductors allows for the study of point defects. Very few techniques exist which allow for the extraction of as much information of their properties. This study focuses on diffusion in the semiconductor gallium antimonide (GaSb). As will become clear, this compound semiconductor proves to be a powerful one for investigating both self- and foreign atom diffusion. While the results have direct applications for work on GaSb devices, the results should also be taken in the broader context of III-V semiconductors. Results here can be compared and contrasted to results in systems such as GaAs and even GaN, indicating trends within this common group of semiconductors. The results also have direct importance for ternary and quaternary semiconductor systems used in devices such as high speed InP/GaAsSb/InP double heterojunction bipolar transistors (DHBT) [Dvorak, (2001)]. Many of the findings which will be reported here were previously published in three journal articles. Hartmut Bracht was the lead author on two articles on self-diffusion studies in GaSb [Bracht, (2001), (2000)], while this report's author was the lead author on Zn diffusion results [Nicols, (2001)]. Much of the information contained herein can be found in those articles, but a more detailed treatment is presented here.

  5. Magnetic and thermal properties of dysprosium aluminum garnet. III. Multiaxis phase transitions

    Microsoft Academic Search

    D. P. Landau; B. E. Keen

    1979-01-01

    Dysprosium aluminum garnet is a cubic antiferromagnet with highly anisotropic moments along +\\/-x, +\\/-y, and +\\/-z directions. In weak magnetic fields applied along any direction the zero-field antiferromagnetic state is stable. In strong magnetic fields, of the order of 10 kOe, applied along [110] or [001], those spins with a component along the field are driven paramagnetic. Because of the

  6. Magnetic and Thermal Properties of Dysprosium Aluminum Garnet. II. Characteristic Parameters of an Ising Antiferromagnet

    Microsoft Academic Search

    W. P. Wolf; B. Schneider; D. P. Landau; B. E. Keen

    1972-01-01

    Extensive earlier work has indicated that dysprosium aluminum garnet (DAG) in a magnetic field along a (111) axis should approximate to a two-sublattice Ising-model antiferromagnet, and in this paper we examine this correspondence critically. Quantitative estimates are derived for the differences between the ideal model and the real material, and it is shown that they are in fact very small

  7. The elasticity of the upper mantle orthosilicates olivine and garnet to 3 GPa

    Microsoft Academic Search

    Sharon L. Webb

    1989-01-01

    The elastic moduli of single crystals of pyrope-rich garnet and San Carlos olivine have been measured over a 3 GPa pressure range at room temperature. The combination of improved ultrasonic techniques and this large pressure range provide for more reliable characterization of the pressure dependence of acoustic wave velocities than has previously been possible. First and second pressure derivatives of

  8. Compositional causes of velocity variations in garnet peridotite xenoliths from the Kaapvaal Craton, South Africa

    Microsoft Academic Search

    D. L. Schutt; C. E. Lesher

    2006-01-01

    To investigate the effects of compositional variations on the velocity and density of the upper mantle, we perform a principle component analysis on the modal variability of > 200 garnet peridotite xenoliths from the Archean Kaapvaal craton. Since peridotite melting relations change with depth, we consider xenolith compositional variations as a function of equilibration pressure, by examining all xenoliths that

  9. Cation-deficient phlogopitic mica exsolution in diopside from garnet peridotite in SuLu, China

    E-print Network

    Cation-deficient phlogopitic mica exsolution in diopside from garnet peridotite in SuLu, China K-deficient phlogopitic mica within diopside of a drill core from the UHPM terrane of SuLu, China. Detailed analysis by transmission electron microscopy (TEM) shows these precipitates to be phlogopitic mica that is highly complex

  10. Near theoretical microwave loss in hot isostatic pressed (hipped) polycrystalline yttrium iron garnet

    Microsoft Academic Search

    Alexey V. Nazarov; David Me´nard; Jerome J. Green; Carl E. Patton; Gil M. Argentina; H. J. Van Hook

    2003-01-01

    The ferromagnetic resonance (FMR) linewidth, the field dependent effective linewidth, and the parallel pump spin wave linewidth were measured for spheres and disks prepared from a block of hot isostatic pressed (hipped) polycrystalline yttrium iron garnet (YIG). All linewidths as well as static magnetization data indicate close to 100% density. Vibrating sample magnetometer measurements give an average saturation induction 4?Ms

  11. Near theoretical microwave loss in hot isostatic pressed (hipped) polycrystalline yttrium iron garnet

    Microsoft Academic Search

    Alexey V. Nazarov; David Ménard; Jerome J. Green; Carl E. Patton; Gil M. Argentina; H. J. van Hook

    2003-01-01

    The ferromagnetic resonance (FMR) linewidth, the field dependent effective linewidth, and the parallel pump spin wave linewidth were measured for spheres and disks prepared from a block of hot isostatic pressed (hipped) polycrystalline yttrium iron garnet (YIG). All linewidths as well as static magnetization data indicate close to 100% density. Vibrating sample magnetometer measurements give an average saturation induction 4piMs

  12. The partitioning of rare earth elements between garnet and liquid at high pressures: Preliminary experiments

    Microsoft Academic Search

    N. Shimizu; I. Kushiro

    1975-01-01

    Preliminary experiments were made to determine the partition coefficients of rare earth elements between garnet and liquid at 30 kb and 1275°C in the system diopside (30 wt%) -pyrope(70%) -water. REE were added to the system by titration at concentration levels in the range of natural basalts. The phases were separated by differential dissolution technique (DDT) and analized for REE

  13. Magnetically switched electric polarity of domain walls in iron garnet films

    Microsoft Academic Search

    A. P. Pyatakov; D. A. Sechin; A. S. Sergeev; A. V. Nikolaev; E. P. Nikolaeva; A. S. Logginov; A. K. Zvezdin

    2011-01-01

    Spiral multiferroics whose ferroelectricity is driven by spatial spin modulation attract considerable attention due to strong magnetoelectric coupling observed in them. The present paper shows that a similar mechanism is involved in the case of conventional micromagnetic structures such as domain walls. It is shown experimentally and theoretically that the domain wall in iron garnet films has electric polarization which

  14. Charge Transfer between Magnetic Anisotropic Centers in Garnet Lattice under an Influence of Eliptically Polarized Light

    Microsoft Academic Search

    I. Davidenko

    2001-01-01

    Electron transitions between magnetic anisotropic impurity centers in garnet crystal lattice under the influence of elliptically polarized light are considered. The theoretical model of the occupancies kinetics of such centers was developed. Spatially inhomogeneous distribution of the energy of photoinduced magnetic anisotropy was calculated in the sample being illuminated with light with modulated polarization. A conclusion about a possibility of

  15. Plant trash in linters and willowed picker: materials used in the cotton garnetting industry

    Microsoft Academic Search

    P. R. MOREY; P. J. WAKELYN

    1976-01-01

    First cut linters and willowed picker, used in cotton garnetting, were examined for content of cotton bract and other plant trash. Bract was found to be a minimal contaminant of the trash of first cut linters. A significant amount of bract (about 9% of the trash) was present in willowed picker. Cotton seed hulls, a valuable oil mill byproduct, contained

  16. Magneto-optical garnet waveguides on semiconductor platforms: Magnetics, mechanics, and photonics

    NASA Astrophysics Data System (ADS)

    Sung, Sang-Yeob; Sharma, Anirudh; Block, Andrew; Keuhn, Katherine; Stadler, Bethanie J. H.

    2011-04-01

    Garnet films with thicknesses of 100-1000 nm and waveguides with widths of 700-2000 nm were grown onto Si to characterize the mechanical stresses that occurred upon crystallization (700-800 °C) by rapid thermal annealing. These magneto-optical garnet films and also photonic crystals have proposed uses in magnetic flux indicator films, integrated photonic devices, such as isolators, circulators, and polarization transformers, because their Verdet constants per unit loss are orders of magnitude better than other magneto-optical materials. However, garnet does not match Si-based materials mechanically with thermal expansion coefficients of 10.4 ppm/°C. These waveguides were optimized to have low losses in the near infrared, including the telecommunication wavelengths (1.0-2.3 dB/mm at 1.3 ?m and 0.9-1.7 at 1.55 ?m). The waveguide losses increased with waveguide width. Finite difference time domain simulations were used to estimate the number, effective index, and profile of modes in each guide. The polarization and localization of modes near guide surfaces effectively explain the trend in losses versus width. With Faraday rotations of 0.2 dB/?m and 1.0 dB/mm loss, this integrated garnet has great potential for a multitude of photonic devices, including isolators, circulators, and mode converters.

  17. Magneto-Optical Properties of Terbium Aluminum Garnet at Liquid-Helium Temperatures

    Microsoft Academic Search

    Warren Desorbo

    1967-01-01

    The Verdet constant of a terbium aluminum garnet crystal (flat disk) has been measured at liquid-helium temperatures in the visible spectral range. Values appropriate to a sample with no demagnetizing field have been calculated from internal fields of the specimen rather than the external field, using standard demagnetization corrections and volume-susceptibility data. Photographs taken of the crystal in field values

  18. COMPARATIVE EVALUATION OF R3f GARNET BEAD FILTRATION AND MULTIMEDIA FILTRATION SYSTEMS; FINAL REPORT

    EPA Science Inventory

    This report summarizes the results of tests conducted to date at the EPA T&E Facility on the R3f filtration system utilizing fine beads (such as garnet beads or glass beads) and a conventional multimedia filtration system. Both systems have been designed and built by Enprotec, a...

  19. An Occurrence of Metastable Cristobalite in High-Pressure Garnet Granulite

    E-print Network

    Bodnar, Robert J.

    An Occurrence of Metastable Cristobalite in High-Pressure Garnet Granulite Robert S. Darling, I enough internal pressure decrease to promote the metastable crystallization of cristobalite. Cristobalite between 1470° and 1728°C at a pressure of 1 atm (1). However, it can persist metastably to much lower

  20. Cation-deficient phlogopitic mica exsolution in diopside from garnet peridotite in SuLu, China

    Microsoft Academic Search

    K. N. Bozhilov; Z. Xuc; L. F. Dobrzhinetskaya; Z-M Jin; H. W. Green II

    2009-01-01

    Deep subduction and return to the surface of sediments and other continental rocks is now well known, forming terranes of ultrahigh-pressure metamorphism (UHPM). A common constituent of these terranes is garnet peridotite, mantle rock that has been brought to the surface along with the returning subducted material. Microstructures of these peridotites, especially precipitates within their constituent minerals, offer promise of

  1. Intrinsic pinning of a ferromagnetic domain wall in yttrium iron garnet films with strong uniaxial anisotropy

    Microsoft Academic Search

    K. S. Novoselov; S. V. Dubonos; S. V. Morozov; E. W. Hill; I. V. Grigorieva; A. K. Geim

    2005-01-01

    Movements of individual domain walls in a ferromagnetic garnet were studied with angstrom resolution. The measurements reveal\\u000a that domain walls can be locked between adjacent crystallographic planes and propagate by distinct steps matching the lattice\\u000a periodicity.

  2. (Data in kilograms of gallium content, unless noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1995. Two companies in

    E-print Network

    .S. gallium consumption, were valued at about $3.5 million. Gallium arsenide (GaAs) components represented, submicron semiconductor device manufacturing, and medical applications. As one step to developing high semiconductor chip. This type of component can be used for processing optical signals, such as infrared light

  3. Erbium, chromium:yttrium scandium gallium garnet laser for caries removal: influence on bonding of a self-etching adhesive system

    Microsoft Academic Search

    Arlene Tachibana; Márcia Martins Marques; Julia Maria Pavan Soler; Adriana Bona Matos

    2008-01-01

    This study evaluated the influence of the dental substrates obtained after the use of different caries removal techniques\\u000a on bonding of a self-etching system. Forty, extracted, carious, human molars were ground to expose flat surfaces containing\\u000a caries-infected dentine surrounded by sound dentine. The caries lesions of the specimens were removed or not (control—G1)\\u000a either by round steel burs and water-cooled,

  4. Garnet and spinel in fertile and depleted mantle: insights from thermodynamic modelling

    NASA Astrophysics Data System (ADS)

    Ziberna, Luca; Klemme, Stephan; Nimis, Paolo

    2013-08-01

    We performed thermodynamic calculations based on model and natural peridotitic compositions at pressure and temperature conditions relevant to the Earth's upper mantle, using well-established free energy minimization techniques. The model is consistent with the available experimental data in Cr-bearing peridotitic systems and can therefore be used to predict phase relations and mineral compositions in a wide range of realistic mantle compositions. The generated phase diagrams for six different bulk compositions, representative of fertile, depleted and ultra-depleted peridotitic mantle, shown that the garnet + spinel stability field is always broad at low temperatures and progressively narrows with increasing temperatures. In lithospheric sections with hot geotherms (ca. 60 mW/m2), garnet coexists with spinel across an interval of 10-15 km, at ca. 50-70 km depths. In colder, cratonic, lithospheric sections (e.g. along a 40 mW/m2 geotherm), the width of the garnet-spinel transition strongly depends on bulk composition: In fertile mantle, spinel can coexist with garnet to about 120 km depth, while in an ultra-depleted harzburgitic mantle, it can be stable to over 180 km depth. The formation of chromian spinel inclusions in diamonds is restricted to pressures between 4.0 and 6.0 GPa. The modes of spinel decrease rapidly to less than 1 vol % when it coexists with garnet; hence, spinel grains can be easily overlooked during the petrographical characterization of small mantle xenoliths. The very Cr-rich nature of many spinels from xenoliths and diamonds from cratonic settings may be simply a consequence of their low modes in high-pressure assemblages; thus, their composition does not necessarily imply an extremely refractory composition of the source rock. The model also shows that large Ca and Cr variations in lherzolitic garnets in equilibrium with spinel can be explained by variations of pressure and temperature along a continental geotherm and do not necessarily imply variations of bulk composition. The slope of the Cr# [i.e. Cr/(Cr + Al)mol] isopleths in garnet in equilibrium with spinel changes significantly at high temperatures, posing serious limitations to the applicability of empirical geobarometric methods calibrated on cratonic mantle xenoliths in hotter, off-craton, lithospheric mantle sections.

  5. Lu-Hf garnet geochronology of the Salmon River Suture Zone, West-Central Idaho

    NASA Astrophysics Data System (ADS)

    Wilford, D. E.; Vervoort, J. D.; Lewis, R.; Tikoff, B.

    2011-12-01

    The Salmon River Suture Zone (SRSZ) in west-central Idaho records the accretion of island arc terranes to North America. It is modified by the Western Idaho Shear Zone (WISZ), a high strain zone within the SRSZ, which defines the present-day boundary between old continental North America and the accreted oceanic assemblages. Timing of the onset of deformation on the WISZ is not well established, primarily due to a poorly constrained metamorphic history. Existing garnet geochronologic studies of units within the SRSZ, using the Sm-Nd isotope system, have provided a framework towards a progressive accretion of arc-derived rocks to North America [1,2]. In this study, we report on the application of the Lu-Hf isotope system to provide ages of garnet growth within the suture zone. This system has the advantage of being insensitive to light rare earth element (LREE)-rich inclusions in garnet, which can complicate Sm-Nd geochronology. Samples were taken from several locations from both along and perpendicular to the suture zone. We report results on two of these samples, within and east of the WISZ. First, a garnet bearing leucocratic layer in a gneissic meta-sedimentary screen near Cascade, Idaho, yields a garnet age of 98 ± 2.0 Ma (2SD). The screen occurs completely within the orthogneisses of the WISZ, and displays similar fabrics and kinematics. Second, a biotite quartzo-feldspathic garnet gneiss from Elk City, Idaho, yields an age 100 ± 2.9 Ma (2SD). This location is ~35 km east of the WISZ, on a sub-parallel deformation zone that was active at the same time. Both samples were single-stage garnet fractions consisting of inclusion-free to inclusion-bearing fragments and whole rock pairs. These ages provide two important implications for the Mesozoic evolution of the western edge of North America. First, transpressional deformation in the WISZ occurred simultaneously with deformation on parallel structures in central Idaho, indicating that a wide zone of deformation occurred on North America (and was intruded and thus obscured by the younger Idaho batholith). Second, deformation on these structures occurred during a limited time interval in the mid-Cretaceous, with peak metamorphism at ~100 Ma. [1] Getty et al., 1993, Contrib. Mineral. Petrol, v. 115, p. 45-57. [2] McKay et al., 2011, GSA Abstr w Prog., 2011 Rocky Mountain-Cordilleran section meeting, Paper No. 26-2.

  6. Extracellular biodegradable macromolecular gadolinium(III) complexes for MRI.

    PubMed

    Lu, Zheng-Rong; Parker, Dennis L; Goodrich, K Craig; Wang, Xinghe; Dalle, John G; Buswell, Henry R

    2004-01-01

    The clinical application of macromolecular gadolinium (Gd) complexes as MRI contrast agents is limited by the slow excretion of Gd(III) complexes and consequent long-term tissue accumulation of toxic Gd ions. To alleviate the problem of slow excretion, biodegradable polydisulfide-based macromolecular Gd(III) complexes were designed and prepared based on the disulfide-thiol exchange to allow degradation of the macromolecules by endogenous thiols and to facilitate excretion of Gd(III) complexes after the MRI examination. The in vitro degradation study showed that the polydisulfide agent was readily degraded by cysteine at plasma thiol concentrations. No cross-reaction was observed between the cysteine-34 on human serum albumin (HSA) with the agent. Concentration-dependent blood pool contrast enhancement was observed for the polydisulfide agents. The agents of both high molecular weight (35,000 Da) and low molecular weight (17,700 Da) produced significant contrast enhancement in the heart and aorta in rats at relatively high doses. Except for the bladder, the signal intensities gradually decreased over time. Significant blood pool contrast enhancement was also observed for the high molecular weight agent at a low dose (0.03 mmol-Gd/kg), but not for the agent with a lower molecular weight. The contrast enhancement in the urinary bladder increased over time for the polydisulfide agents and Gd(III)-(DTPA-BMA). Degradation products were identified by mass spectrometry in the urine samples from the rats administered with both polydisulfide agents, which confirmed that the polydisulfide agents were degraded in vivo and excreted through renal filtration. The preliminary results demonstrated the in vitro and in vivo degradability, superior blood pool contrast enhancement, and rapid clearance through renal filtration of the novel biodegradable macromolecular agent. This agent has a great potential for further preclinical and clinical development with application in contrast-enhanced blood pool and cancer MR imaging. PMID:14705042

  7. Magnetocaloric effect of an Fe-based metallic glass compared to benchmark gadolinium

    NASA Astrophysics Data System (ADS)

    Waske, A.; Hermann, H.; Mattern, N.; Skokov, K.; Gutfleisch, O.; Eckert, J.

    2012-12-01

    We report on the magnetocaloric effect in an Fe-based metallic glass (Fe80B12Nb8) as compared to the benchmark material gadolinium. From temperature-dependent magnetization measurements, the magnetic entropy change was calculated using the thermodynamic Maxwell relations. The adiabatic temperature change was directly measured for both materials using a dedicated setup. An analysis of the magnetic transition in amorphous Fe80B12Nb8 and crystalline gadolinium using a mean field and a phenomenological model was carried out. It was shown that both materials, in particular crystalline gadolinium, which does not possess structural disorder but merely a fluctuation of the exchange integral, can be described using the Handrich model for the magnetic transition of disordered materials. Furthermore, the Landau theory of second-order phase transitions quantitatively describes the magnetic entropy change and its dependence on the applied field very well for both materials with different definitions of disorder.

  8. Modeling gadolinium-bearing fuel in Ringhals PWRs using CASMO/SIMULATE

    SciTech Connect

    Kurcyusz, E. (Vattenfall AB, Ringhals, Varoebacka (Sweden))

    1993-01-01

    Ringhals units 2, 3, and 4 are Westinghouse three-loop, 157-assembly pressurized water reactors (PWRs) operated by Vattenfall. Originally, all three reactors were loaded in an out-in scheme using reload fuel without burnable poisons. In recent cycles, gadolinium-bearing fuel was introduced to enable a low-leakage loading pattern and minimize fuel cycle costs. This paper focuses on the Fragema 17 x 17 AFA design with peripheral gadolinium rods loaded in units 3 and 4. The Ringhals units are modeled using the Studsvik core management system, consisting of the CASMO-3 transport theory lattice physics code,and the SIMULATE-3 advanced nodal reactor analysis code. The results of the studies verifying the accuracy of CASMO-3/SIMULATE-3 on the assemblies with peripheral gadolinium rods are presented in this paper. The verification was carried out against CASMO-3 color-set calculations and measured reactor data.

  9. Influence of gadolinium concentration on the EMR spectrum of Gd 3+ in zircon

    NASA Astrophysics Data System (ADS)

    de Biasi, R. S.; Grillo, M. L. N.

    2009-11-01

    Electron magnetic resonance (EMR) spectra of gadolinium-doped zircon (ZrSiO 4) powders have been studied at room temperature for gadolinium concentrations between 0.20 and 1.0 mol%. The results suggest that Gd 3+ ions occupy substitutional sites in the zircon lattice, that the electron magnetic resonance linewidth increases with increasing gadolinium concentration and that the range of the exchange interaction between Gd 3+ ions is about 1.17 nm, larger than that of the same ion in other host lattices, such as ceria (CeO 2), strontium oxide (SrO) and calcium oxide (CaO). The fact that the electron magnetic resonance linewidth of the Gd 3+ ion in polycrystalline zircon increases, regularly and predictably, with Gd concentration, shows that the Gd 3+ ion can be used as a probe to study, rapidly and non-destructively, the crystallinity and degradation of ZrSiO 4.

  10. Intravenous chelated gadolinium as a contrast agent in NMR imaging of cerebral tumours.

    PubMed

    Carr, D H; Brown, J; Bydder, G M; Weinmann, H J; Speck, U; Thomas, D J; Young, I R

    1984-03-01

    NMR imaging was performed on 12 patients with cerebral tumour before and after administration of intravenous gadolinium diethylene triamine penta-acetic acid (DTPA) (0.1 mmol/kg). Contrast enhancement was seen in all cases. Ring enhancement was most frequent (7 cases) but central, linear, patchy, and diffuse enhancement were also seen with both inversion-recovery and spin-echo sequences. The degree of enhancement was greater than that seen with X-ray computed tomography (CT) in 8 cases, equal to it in 3 cases, and less in 1 case. NMR distinguished between tumour and peritumoral oedema to the same extent as did CT. No side-effects were encountered and there was no significant change in urea, creatinine and electrolytes, liver function tests, blood coagulation, or urine testing after administration of gadolinium-DTPA. Gadolinium-DTPA is likely to be of considerable value in NMR imaging of the brain. PMID:6142210

  11. Garnet-melt Trace Element Partitioning From 5 to 9 GPa: Onset of Garnet to Majorite Transformation

    NASA Astrophysics Data System (ADS)

    Draper, D. S.; Xirouchakis, D.; Agee, C. B.

    2002-05-01

    Garnet (Gt) and its higher-pressure form, majorite (Mj), are thought to play important roles in the generation of terrestrial Archaean komatiites and of Martian meteorite compositions. Earlier work by Ohtani, Kato, and coworkers on majoritic Gt partitioning at 16-24 GPa showed that DHREE for Mj were somewhat lower, and DLREE somewhat higher, than those for lower-pressure Gt. Thus, REE signatures of Mj fractionation are less pronounced than those for ordinary Gt, and because DHf is less affected, Lu/Hf will be less strongly perturbed by Mj fractionation than by Gt fractionation. In this study, we were motivated to measure Gt-melt trace element partitioning in more iron-rich systems than were used in these earlier studies, which are more relevant to early Martian magmatism. However, our results have general applicability and form a useful comparison with the studies of van Westrenen and coworkers (e.g. 2001, CMP 142:219), who developed predictive relationships for 3+ cation partitioning into the X sites of lower-pressure Gt. We doped a synthetic ultramafic composition, based on the silicate portion of Homestead L5 ordinary chondrite, with various subsets of Nd, Sm, Tb, Yb, Lu, Y, Sc, Zr, and Hf (max total dopant ~2 wt%) for multianvil experiments between 5 and 9 GPa. Gt begins to exhibit the transformation to Mj at 5 GPa, a lower pressure than has been previously reported. This transformation is evidenced by decreasing Al and excess Si per formula unit (e.g. 3.1 to 3.2 Si per 12 oxygens), becoming progressively more majoritic (increasing Si, decreasing Al) with increasing pressure to ~3.3 Si per 12 oxygens at 9 GPa. We have reported elsewhere (Xirouchakis et al., 2002, XXXIII LPSC, 1316) that the Mj transformation is favored at these lower pressures by the presence of silicate melt and the absence of clinopyroxene. We find that DHREE,Y and DTb decrease markedly as Gt begins the transformation to Mj, but that the LREE are less affected. DHf,Zr undergo almost no change, and DSc shows a slight decrease with increasing pressure. Ds for 3+ cations into the X sites follow very closely the functional form of the lattice-strain model of Blundy and Wood (1994, Nature 372:452), in similar fashion to the data of van Westrenen et al. However, the observed D values do not match their predictions, suggesting that the transformation to Mj involves structural changes that have an important effect on trace element partitioning. Our data should improve the predictive power of the lattice-strain model with respect to the Mj transformation. To help model 4+ cation partitioning into the Y sites using the same formulation, we sought to estimate Ds for SiVI between Gt and melt. We estimated octahedral SiO2 in Gt using the expression [(Si per 12 oxygens - 3)/(Si per 12 oxygens)] x (wt% SiO2 in garnet), and then simply divided that quantity by the SiO2 content of the quench phase to obtain DSiVI. Combining those values with Ds for Hf, Zr, and Ti results in fits to the Blundy and Wood model that make some qualitative sense: site elasticity E, ideal partition coefficient D0, and ideal site-size r0 are all smaller than those for the X sites. However, there is an indication that elasticity decreases with increasing pressure, and r0 values are substantially higher than those found by van Westrenen et al. for Ca-poor Gt (75 to 80 pm compared to 67 pm). These results may be artifacts of having data on fewer elements from which to calculate the fits compared to the 3+ situation. Accordingly, we require further work that adds a larger cation such as Th to our element set before robust quantitative assessments of our 4+ data can be made.

  12. A generalized garnet-forming reaction for metaigneous rocks in the Adirondacks

    USGS Publications Warehouse

    McLelland, J.M.; Whitney, P.R.

    1980-01-01

    A generalized reaction is presented to account for garnet formation in a variety of Adirondack metaigneous rocks. This reaction, which is the sum of five partial reactions written in aluminum-fixed frames of reference, is given by: 4(y+1+w)Anorthite+4 k(y+1+2 w)Olivine +4(1-k)(y+1+2 w)Fe-oxide+(8(y+1) -4 k(y+1+2 w))Orthopyroxene = 2(y+1)Garnet +2(y+1+2 w)Clinopyroxene+4 wSpinel where y is a function of plagioclase composition, k refers to the relative amounts of olivine and Fe-oxide participating in the reaction, and w is a measure of silicon mobility. When mass balanced for Mg and Fe, this reaction is found to be consistent with analyzed mineral compositions in a wide range of Adirondack metaigneous rocks. The reaction applies equally well whether the garnets were formed directly from the rectants given above or went through an intermadiate stage involving the formation of spinel, orthopyroxene, and clinopyroxene. The actual reactions which have produced garnet in both undersaturated and quartz-bearing rocks are special cases of the above general reaction. The most important special cases appear to be those in which the reactants include either olivine alone (k=1) or Fe-oxide alone (k=0). Silicon is relatively immobile (w =2) in olivine bearing, magnesium-rich rocks (k???1), and this correlates with the increased intensity in spinel clouding of plagioclase in these rocks. Silicon mobility apparently increases in the more iron-rich rocks, which also tend to contain clear or lightly clouded plagioclase. In all the rocks studied the most common composition of metamorphic plagioclase is close to An33 (i.e., y=1). Plagioclase of lower anorthite content may be too sodic to participate in garnet formation at the P-T conditions involved. ?? 1980 Springer-Verlag.

  13. [Gemology and spectra characterization of gem garnet from Muling City, Heilongjiang Province].

    PubMed

    Chen, Tao; Liu, Yun-Gui; Yin, Zuo-Wei; Liu, Ni

    2013-11-01

    Cenozoic basalts gem-garnets from Muling City, Heilongjiang Province were studied by using standard gemological methods, electron microprobe, Raman spectroscopy, infrared spectroscopy, and ultraviolet-visible spectroscopy to obtain the gemology and spectra characterization. Chemical composition analysis indicates that the garnets are pyropes with some impurity element Fe, Ca, Mn, Cr, and Ti. The average chemical structure formula of the gem-garnet is (Mn0.022 Ca0.455, Fe(2+)0.720, Mg1.793) sigma = 2.990 (Ti0.003 Cr0.009 Fe(3+)0.062 Al1.951) sigma = 2.025 (SiO4)3. Roman spectrum analysis suggests that there are mixed-phases in the garnet, which can be shown by the Roman shift which is caused by bridging oxygen vibration of garnet. The Roman shifts of bridging oxygen bending vibration of pyrope are at 560 cm(-1) (A(1g)), and 641 cm(-1) (E(g) + F(2g)), while the Roman shifts of bridging oxygen bending vibration caused by E(g) + F(2g) of almandine and grossular are at 507 and 486 cm(-1). IR functional group area indicates that the pyropes have no molecules water, but seldom pyropes have a little structure water, which forms three stepped weak absorption peaks at 3 585, 3 566 and 3 544 cm(-1) respectively. Most pyropes are brown-red, which is caused by electronic transitions of impurity ions Cr3+, Fe3+ and Mn2+. UV-Vis spectra show that absorption peaks caused by electron transition of Fe3+ are at 570, 521 and 502 nm, while absorption peaks caused by electron transition of Mn2+ are at 460 and 430 nm, and absorption peaks caused by electron transition of Cr3+ are at 690 and 367 nm. PMID:24555361

  14. Gadolinium-Conjugated Gold Nanoshells for Multimodal Diagnostic Imaging and Photothermal Cancer Therapy

    PubMed Central

    Coughlin, Andrew J.; Ananta, Jeyarama S.; Deng, Nanfu; Larina, Irina V.; Decuzzi, Paolo

    2014-01-01

    Multimodal imaging offers the potential to improve diagnosis and enhance the specificity of photothermal cancer therapy. Toward this goal, we have engineered gadolinium-conjugated gold nanoshells and demonstrated that they enhance contrast for magnetic resonance imaging, X-Ray, optical coherence tomography, reflectance confocal microscopy, and two-photon luminescence. Additionally, these particles effectively convert near-infrared light to heat, which can be used to ablate cancer cells. Ultimately, these studies demonstrate the potential of gadolinium-nanoshells for image-guided photothermal ablation. PMID:24115690

  15. Toward an image-guided microbeam radiation therapy using gadolinium-based nanoparticles.

    PubMed

    Le Duc, Géraldine; Miladi, Imen; Alric, Christophe; Mowat, Pierre; Bräuer-Krisch, Elke; Bouchet, Audrey; Khalil, Enam; Billotey, Claire; Janier, Marc; Lux, François; Epicier, Thierry; Perriat, Pascal; Roux, Stéphane; Tillement, Olivier

    2011-12-27

    Ultrasmall gadolinium-based nanoparticles (GBNs) induce both a positive contrast for magnetic resonance imaging and a radiosentizing effect. The exploitation of these characteristics leads to a greater increase in lifespan of rats bearing brain tumors since the radiosensitizing effect of GBNs can be activated by X-ray microbeams when the gadolinium content is, at the same time, sufficiently high in the tumor and low in the surrounding healthy tissue. GBNs exhibit therefore an interesting potential for image-guided radiotherapy. PMID:22040385

  16. Garnet-bearing tonalitic porphyry from East Kunlun, Northeast Tibetan Plateau: implications for adakite and magmas from the MASH Zone

    Microsoft Academic Search

    Chao Yuan; Min Sun; Wenjiao Xiao; Simon Wilde; Xianhua Li; Xiaohan Liu; Xiaoping Long; Xiaoping Xia; Kai Ye; Jiliang Li

    2009-01-01

    A garnet-bearing tonalitic porphyry from the Achiq Kol area, northeast Tibetan Plateau has been dated by SHRIMP U-Pb zircon\\u000a techniques and gives a Late Triassic age of 213 ± 3 Ma. The porphyry contains phenocrysts of Ca-rich, Mn-poor garnet (CaO > 5 wt%;\\u000a MnO 2O3 ~ 15.9 wt%), plagioclase and quartz, and pressure estimates for hornblende enclosing the garnet phenocrysts yield values\\u000a of 8–10 kbar, indicating a minimum pressure for the

  17. Development of liquid phase epitaxy-grown (Bi, Gd, Lu)-substituted thin-film iron garnets

    NASA Astrophysics Data System (ADS)

    Nistor, I.; Holthaus, C.; Mayergoyz, I. D.; Krafft, C.

    2006-04-01

    The liquid phase epitaxy growth of single-crystal iron garnet thin films of composition Gd3-x-yLuxBiyFe5-zGazO12 is discussed. The Bi, Lu, and Gd contents are identified for which the garnet films have in-plane magnetization as well as sufficiently large Faraday rotation and can be grown at relatively small melt undercooling temperatures. The results of extensive characterization of the magnetic and optical properties of these garnet films as a function of melt compositions and undercooling are reported.

  18. Contrasting behaviour of anthropogenic gadolinium and natural rare earth elements in estuaries and the gadolinium input into the North Sea

    NASA Astrophysics Data System (ADS)

    Kulaks?z, Serkan; Bau, Michael

    2007-08-01

    All major rivers in northwestern Germany that flow into the North Sea, including the Weser River, display rare earth element (REE) patterns with large positive gadolinium (Gd) anomalies that indicate the presence of anthropogenic Gd derived from contrast agents used in magnetic resonance imaging. This microcontaminant cannot be removed by common sewage treatment technology and enters rivers and lakes with the discharge from waste water treatment plants. As elsewhere, a large fraction of the natural dissolved REE in the Weser River are associated with colloids. These colloids aggregate during mixing of freshwater and seawater in the low-salinity part of the Weser Estuary and the dissolved REE are partially removed from the river water together with the colloids. In marked contrast to the natural REE, the anthropogenic Gd behaves conservatively during this estuarine mixing and transits through the Weser Estuary almost unaffected. This indicates that the speciation of anthropogenic Gd is different from that of natural Gd and suggests a long environmental half-life of the anthropogenic Gd complexes used as contrast agents. The amount of anthropogenic Gd introduced into seawater via rivers is significant and produces anthropogenic positive Gd anomalies in coastal seawater. This is observed in the southwestern North Sea, off the coast of the East Frisian Islands, where anthropogenic Gd is mostly derived from the rivers Rhine and Thames. Its long environmental half-life and conservative estuarine behaviour suggest that anthropogenic Gd might be utilized as a pseudo-natural far-field tracer for truly dissolved riverine REE input into seawater and for discharge from waste water treatment plants and for sewage in river, ground and drinking water. The widespread distribution of anthropogenic Gd is an example of how the increasing use of "exotic" (ultra)trace elements in high-tech processes will in the future significantly hamper studies of the distribution and geochemical behaviour of such elements in natural systems.

  19. Arene complexes of gallium: An effective tool for the synthesis of transition metal clusters and complexes

    Microsoft Academic Search

    Mikhail Gorlov; Lars Kloo

    2008-01-01

    In this review, the interactions between gallium(III) halides or gallium(I) subvalent halides and aromatic hydrocarbons in solution and solid state are discussed. Such unique properties of gallium halides–arene mixtures as the ability to reduce metallic centers and accept halide atoms make them very efficient tool for the preparation of low-valent clusters and complexes of transition metals. Diverse mono- and polynuclear

  20. Purification of gallium from bismuth and polonium by melting under synthetic slags

    Microsoft Academic Search

    L. Wali?; L. Rowi?ska; A. Nowicki

    1994-01-01

    A method for the purification of technical grade gallium from bismuth and polonium by melting under synthetic slags is proposed. The examination of the purification degrees of gallium from bismuth and polonium was carried out with the aid of radioactive tracers210Bi and210Po. In order to obtain a gallium-bismuth alloy a suitable apparatus was assembled. The conditions of melting were established.

  1. Gallium-Cooled Target for Compact Accelerator-Based Neutron Sources

    NASA Astrophysics Data System (ADS)

    Carpenter, John M.

    This paper discusses the motivation for gallium cooling of targets of compact accelerator-based neutron sources (CANS); summarizes features of the low-power alternative, i.e., water cooling, and the limitations of boiling water heat transfer; lists the properties of liquid gallium; and cites its low hazards potential. I set out working equations for heat transport and fluid flow in liquid gallium and present a concept for a gallium-cooled system, including a scoping calculation of temperatures and pressure drops, and present conclusions and a recommendation.

  2. Distribution of trace elements during breakdown of mantle garnet: an example from Zabargad

    NASA Astrophysics Data System (ADS)

    Vannucci, R.; Shimizu, N.; Piccardo, G. B.; Ottolini, L.; Bottazzi, P.

    1993-12-01

    Ion probe investigations on mineral phases forming the Al-Di pyroxenites from the Zabargad peridotite body indicate that porphyroclastic pyroxenes in composite mafic layers record an unusual HREE, Zr, Sc enrichment not registered by pyroxenes in spinel websterites. Orthopyroxene in the opx+sp clusters forming the inner, cpx-free zone of layered pyroxenites shows strongly fractionated REE patterns (HREEN/LREEN>1000; Yb>100xch) and very high Zr, Sc and Y abundances (up to 30,672 and 60ppm, respectively). In the outer, cpx-rich zone porphyroclastic clinopyroxene is strongly HREE enriched (HREEN/LREEN˜29; Yb˜ 269xch) and displays very high Sc and Zr abundances (up to 819 and 164 ppm, respectively). It is suggested that the unusual trace element abundances are inherited from a precursor garnet. Composite pyroxenite layers are interpreted as former garnet clinopyroxenites characterized by gnt/cpx modal zoning. The sp+opx(cpx-free) assemblage in the inner part is a product of the break-down reaction of garnet upon decompression, with Ca of the original garnet completely entering the enstatite solid solution. The temperature at which the breakdown reaction occurred is estimated to be higher than 1000°C ( P in the range 20 30 kbar). In the outer part, decompression caused the garnet to form a sp+opx assemblage; however, the grossularite component participated in the formation of new clinopyroxene which reacted with the clinopyroxene present in the original mode before the decompression reaction, thus forming a cpx2+sp+opx assemblage. As a result of garnet breakdown, pyroxenes have peculiar HFSE anomalies. Progressive upwelling during the Red Sea rifting produced incomplete reaction under pl-facies conditions. The geochemical signatures of precursor garnet in pyroxenes were partially crased during the recrystallization from granular spincl-bearing to granoblastic plagioclase-bearing assemblages, being preserved only in a few porphyroclast relies. The finding of pyroxenes with trace element characteristics of precursor garnet has important geodynamic and geochemical implications. Al-Di pyroxenite layers had a long history within the mantle, before the continental lithosphere rifting and thinning took place in the region. It is suggested that Al-Di pyroxenites were formed by deep-seated tholeiitic magmatism unrelated to the Red Sea evolution, thus representing the earliest event in the Zabargad upper mantle. Garnet breakdown significantly preceded the metasomatism induced by hydrous fluids (crystallization of Ti-rich pargasite) and the later intrusion of hydrous (Cr-Di) pyroxenite dykes. During the stages of mantle evolution, the HFSE anomalies in pyroxenes varied significantly. We note that the study of HFSE anomalies in mineral phases reveals complex geochemical histories which are not recorded by the whole-rock system.

  3. Detection and quantitation of gadolinium chelates in human serum and urine by high-performance liquid chromatography and post-column derivatization of gadolinium with Arsenazo III

    Microsoft Academic Search

    Erlend Hvattum; Per Trygve Normann; Gene C. Jamieson; Jan-Ji Lai; Tore Skotland

    1995-01-01

    A narrow-bore high-performance liquid chromatography method was developed for simultaneous separation of gadolinium diethylenetriaminepentaacetic acid (GdDTPA), the monomethylamide (GdDTPA-MMA) and the bis-methylamide (GdDTPA-BMA) in human serum and urine. The Gd complexes were detected at 658 nm after post-column derivatization with Arsenazo III. The serum samples were ultrafiltrated, whereas the urine samples were centrifuged and diluted before analysis. With an injection

  4. GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

    SciTech Connect

    Pierce, R.

    2012-02-22

    HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into the H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. For 6 M HNO{sub 3}, 10.5 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2 g/L and 0.25 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}.

  5. Aging and memory effect in magnetoelectric gallium ferrite single crystals

    NASA Astrophysics Data System (ADS)

    Singh, Vijay; Mukherjee, Somdutta; Mitra, Chiranjib; Garg, Ashish; Gupta, Rajeev

    2015-02-01

    Here, we present a time and temperature dependent magnetization study to understand the spin dynamics in flux grown single crystals of gallium ferrite (GaFeO3), a known magnetoelectric, ferroelectric and ferrimagnet. Results of the magnetic measurements conducted in the field-cooled (FC) and zero-field-cooled (ZFC) protocols in the heating and cooling cycles were reminiscent of a "memory" effect. Subsequent time dependent magnetic relaxation measurements carried out in ZFC mode at 30 K with an intermittent cooling to 20 K in the presence of a small field show that the magnetization in the final wait period tends to follow its initial state which was present before the cooling break taken at 20 K. These observations provide an unambiguous evidence of single crystal gallium ferrite having a spin glass like phase.

  6. Thermodynamic properties of liquid gallium from picosecond acoustic velocity measurements

    NASA Astrophysics Data System (ADS)

    Ayrinhac, S.; Gauthier, M.; Le Marchand, G.; Morand, M.; Bergame, F.; Decremps, F.

    2015-07-01

    Due to discrepancies in the literature data the thermodynamic properties of liquid gallium are still in debate. Accurate measurements of adiabatic sound velocities as a function of pressure and temperature have been obtained by the combination of laser picosecond acoustics and surface imaging on sample loaded in diamond anvil cell. From these results the thermodynamic parameters of gallium have been extracted by a numerical procedure up to 10 GPa and 570 K. It is demonstrated that a Murnaghan equation of state accounts well for the whole data set since the isothermal bulk modulus BT has been shown to vary linearly with pressure in the whole temperature range. No evidence for a previously reported liquid–liquid transition has been found in the whole pressure and temperature range explored.

  7. Thermodynamic properties of liquid gallium from picosecond acoustic velocity measurements.

    PubMed

    Ayrinhac, S; Gauthier, M; Le Marchand, G; Morand, M; Bergame, F; Decremps, F

    2015-07-15

    Due to discrepancies in the literature data the thermodynamic properties of liquid gallium are still in debate. Accurate measurements of adiabatic sound velocities as a function of pressure and temperature have been obtained by the combination of laser picosecond acoustics and surface imaging on sample loaded in diamond anvil cell. From these results the thermodynamic parameters of gallium have been extracted by a numerical procedure up to 10 GPa and 570 K. It is demonstrated that a Murnaghan equation of state accounts well for the whole data set since the isothermal bulk modulus BT has been shown to vary linearly with pressure in the whole temperature range. No evidence for a previously reported liquid-liquid transition has been found in the whole pressure and temperature range explored. PMID:26061830

  8. Hydrothermal preparation and characterization of nanocrystalline. Silver gallium sulfides

    NASA Astrophysics Data System (ADS)

    Junqing, Hu; Bin, Deng; Kaibin, Tang; Qingyi, Lu; Rongrong, Jiang; Yitai, Qian

    2001-03-01

    The hydrothermal reaction route was developed to prepare nanocrystalline silver gallium sulfides AgGaS 2 and ?-Ag 9GaS 6, respectively. X-ray powder diffraction patterns indicated tetragonal phase AgGaS 2 with cell constants a=5.765 and c=10.281 Å, and orthorhombic phase ?-Ag 9GaS 6 with cell constants a=10.756, b=7.806, and c=7.605 Å. Transmission electron microscopy images revealed that nanocrystalline AgGaS 2 consisted of uniform spherical particles with grain sizes of 6-12 nm and nanocrystalline ?-Ag 9GaS 6 displayed whisker-like particles with an average size of 20×5 nm. The room temperature photoluminescence spectrum of nanocrystalline AgGaS 2 was found to be one broad emission feature at 446 nm. A possible formation mechanism of silver gallium sulfides was proposed.

  9. Preparation Of Copper Indium Gallium Diselenide Films For Solar Cells

    DOEpatents

    Bhattacharya, Raghu N. (Littleton, CO); Contreras, Miguel A. (Golden, CO); Keane, James (Lakewood, CO); Tennant, Andrew L. (Denver, CO), Tuttle, John R. (Denver, CO); Ramanathan, Kannan (Lakewood, CO); Noufi, Rommel (Golden, CO)

    1998-08-08

    High quality thin films of copper-indium-gallium-diselenide useful in the production of solar cells are prepared by electrodepositing at least one of the constituent metals onto a glass/Mo substrate, followed by physical vapor deposition of copper and selenium or indium and selenium to adjust the final stoichiometry of the thin film to approximately Cu(In,Ga)Se.sub.2. Using an AC voltage of 1-100 KHz in combination with a DC voltage for electrodeposition improves the morphology and growth rate of the deposited thin film. An electrodeposition solution comprising at least in part an organic solvent may be used in conjunction with an increased cathodic potential to increase the gallium content of the electrodeposited thin film.

  10. Heterovalent substitutions in garnet and their implications for diffusion of Y+REEs and alkalis (Invited)

    NASA Astrophysics Data System (ADS)

    Carlson, W. D.; Gale, J. D.; Wright, K.

    2013-12-01

    Lattice-dynamics calculations in the static limit suggest that large trivalent ions (Y+REEs) are incorporated into garnet primarily by means of substitutions that introduce menzerite and alkali components. The diffusion mechanisms implied by this finding explain otherwise puzzling aspects of recent determinations of diffusion rates for Y+REEs and Li in natural systems, bolstering confidence in the validity of those rates. Several substitution schemes have been proposed to provide the charge-balance required for incorporation of trivalent Y+REEs substituting for divalent cations in dodecahedral sites in aluminosilicate garnet: (1) YAG components, with tetrahedral Al; (2) vacancy components, with one unoccupied dodecahedral site for each two trivalent ions; (3) alkali components, with dodecahedral Na or Li; (4) menzerite components, with octahedral Mg or Fe; and (5) Y2Li components, with octahedral Li compensating for a pair of Y+REE ions. The relative energetic costs of these substitutions were evaluated in pyrope, almandine, spessartine and grossular by means of lattice-dynamics calculations at T = 0 K and P = 0 GPa, using well-established force-field potentials, and referencing exchange energies to the lattice energies of binary oxides as sources/sinks for the exchanged ions. Energies calculated for the incorporation of menzerite and alkali components are appreciably lower than those for the YAG component, and very substantially lower than those for the other components. Provided that the relative energetic costs are similar at elevated T and P to those in the static limit (testing of this assumption is currently underway), the menzerite and alkali substitutions should predominate in natural aluminosilicate garnets, the YAG substitution should play only a subordinate role, and the other substitutions should be near-negligible. As a result, diffusion mechanisms for Y+REEs in garnet require that motion of these elements must be coupled to transport of either octahedral Mg/Fe [menzerite], or dodecahedral Na/Li [alkali], or both. Coupling Y+REE transport to the exchange of Mg/Fe for octahedral Al explains several enigmatic aspects of Y+REE diffusion rates, namely: the absence of a strong dependence on either ionic radius or host-garnet composition, the equivalence with rates of Cr diffusion, and strong multicomponent diffusion effects that link the movement of all REEs to the mobility of Y. Coupling of Y+REE and Li transport via the alkali substitution explains the recently observed equivalence of rates of diffusion for Li and Y (and also Yb), with its potential for establishing garnet as a robust recorder of fluid-rock interactions at high T.

  11. A Systematic Study on the Thermal Transport Properties of Natural and Synthetic Garnets

    NASA Astrophysics Data System (ADS)

    Marquardt, H.; Schilling, F.

    2006-12-01

    Knowledge of heat transport properties as a function of mineral- and rock-composition and temperature is of major relevance to understand and model heat transfer in the Earth's interior. The effectiveness of heat transport has many implications on various geological scenarios, e. g. magmatic intrusion, subduction zones, metamorphism in general. Beside its major relevance for geological questions, the knowledge and understanding of thermal transport properties is also very important in material science, e. g. thermal barrier coating, crystal growth, laser applications. To deduce thermal diffusivity from 300-1000K with a high resolution, a transient method^{[1]} was used. The method shows a very good agreement with data obtained from laser flash measurements performed on the same samples. A systematic study on several synthetic garnets was carried out in an attempt to obtain a better systematic understanding of the processes that effects the heat transport in minerals. The investigated garnets are all flawless, single-crystals with a simple, clearly defined composition with systematically varied content of heavy elements (e. g. YxYb3-xAl5O12 solid solution) and are therefore very well suited for studying the substitution-effect on thermal transport properties. The incorporation of heavy elements in an existing garnet significantly lowers the thermal diffusivity. Furthermore, thermal diffusivity of natural garnet solid solutions were measured to transfer the results from simple, synthetic to more complex, natural systems. Like expected, the natural garnets show the same thermal transport principles as the synthetic garnets. With increasing temperature the thermal diffusivity decreases due to vibrational effects. A quantitative analysis of the high-temperature behaviour was carried out, using the theoretical description of Roufosse &Klemens ^{[2]}, which takes a lower limit of thermal diffusivity at elevated temperatures into account. In addition, sound wave velocities were measured to calculate the mean velocity of phonons. A correlation between the density of the sample, the velocity of phonons and the thermal diffusivity is deduced. The mean free path lengths of phonons are in agreement with the theoretical model. [1] Schilling, F. R. (1999) : Eur. J. Mineral. 11, 1115-1124 [2] Roufosse, C. M., Klemens, P. G. (1974): J. Geoph. Res. 79(5), 703-705

  12. Optical and acoustic phonon modes confined in gallium phosphide nanoparticles

    Microsoft Academic Search

    Zhaochun Zhang; Neng Zhang

    2010-01-01

    The main aim of this paper is to discuss the confinement effects on the optical and acoustic phonon vibrational modes in gallium\\u000a phosphide (GaP) nanoparticles (cylindric grain). The Raman scattering from the GaP nanoparticles was investigated. It was\\u000a found that the red-shifts of the longitudinal optical (LO) mode and transverse optical (TO) mode were 15 cm?1 and 13.8 cm?1, respectively.

  13. Copper Indium Gallium Selenide photovoltaic modules manufactured by reactive transfer

    Microsoft Academic Search

    Dingyuan Lu; Baosheng Sang; Yuepeng Deng; B. J. Stanbery; L. Eldada

    2010-01-01

    In recent years, thin-film photovoltaic companies, especially First Solar with its CdTe technology, managed to realize the low manufacturing cost potential and to grab an increasingly larger market share. Copper Indium Gallium Selenide is the most promising thin-film PV material, having demonstrated the highest energy conversion efficiency in both cells and modules. However, most CIGS manufacturers still face the challenge

  14. Incorporation of copper into indium gallium selenide layers from solution

    Microsoft Academic Search

    C. J. Hibberd; M. Ganchev; M. Kaelin; K. Ernits; A. N. Tiwari

    2008-01-01

    A chemical method for the incorporation of copper into indium gallium selenide (IGS) layers has been developed. The resulting copper-containing precursor layers have been annealed in the presence of selenium vapour with the goal of forming Cu(In, Ga)Se2 (CIGS) layers. It is found that copper ions in solution are incorporated into IGS layers during immersion, resulting in the formation of

  15. Intrinsic noise characteristics of gallium nitride high electron mobility transistors

    Microsoft Academic Search

    Sungjae Lee

    2004-01-01

    Wide bandgap gallium nitride high electron mobility transistors (GaN HEMTs) have recently been developed for microwave sources and amplifiers. An experimental and numerical modeling effort is presented to study noise mechanisms within GaN HEMTs. This allows an equivalent-circuit model to be established, facilitating the extraction of intrinsic noise and also microwave circuit design. ^ Intrinsic noise sources in GaN HEMTs

  16. Spectral properties of proton irradiated gallium nitride blue diodes

    Microsoft Academic Search

    François Gaudreau; Cosmo Carlone; Alain Houdayer; Shyam M. Khanna

    2001-01-01

    The permanent damage induced by 2 MeV proton irradiation at room temperature is reported for gallium nitride based blue emitting diodes (CREE model C430-DH85). Both optical and electrical device characteristics were measured. The I-V dependence was obtained as a function of temperature. At low voltages, the current is proportional to the exponential of the voltage at a constant temperature and

  17. Behavior of Zircaloy Cladding in the Presence of Gallium

    Microsoft Academic Search

    J. R. DiStefano; J. F. King; E. T. Manneschmidt; J. P. Strizak; D. F. Wilson

    1998-01-01

    The U.S. Department of Energy has established a dual-track approach to the disposition of plutonium arising from the dismantling of nuclear weapons. Both immobilization and reactor-based mixed-oxide (MOX) fuel technologies are being evaluated. The reactor-based MOX fuel option requires assessment of the potential impact of concentrations of gallium (on the order of 1 to 10 ppm), not present in conventional

  18. Interactions of Zircaloy Cladding with Gallium: Final Report

    Microsoft Academic Search

    D. F. Wilson; E. T. Manneschmidt; J. F. King; J. P. Strizak; J. R. DiStefano

    1998-01-01

    The U.S. Department of Energy has established a dual-track approach to the disposition of plutonium arising from the dismantling of nuclear weapons. Both immobilization and reactor-based mixed-oxide (MOX) fuel technologies are being evaluated. The reactor-based MOX fuel option requires assessment of the potential impact of concentrations of gallium (on the order of 1 to 10 ppm), not present in conventional

  19. A gallium phosphide high-temperature bipolar junction transistor

    Microsoft Academic Search

    T. E. Zipperian; L. R. Dawson; R. J. Caffin

    1981-01-01

    Preliminary results are reported on the development of a high-temperature (> 350°C) gallium phosphide bipolar junction transistor (BJT) for goethermal and other energy applications. This four-layer p\\/sup +\\/n⁻pp\\/sup +\\/ structure was fromed by liquid phase epitaxy using a supercooling technique to insure uniform nucleation of the thin layers. Magnesium was used as the p-type dopant to avoid excessive out-diffusion into

  20. Synthesis and photonic applications of gallium nitride nanowires

    Microsoft Academic Search

    S. Han; Wu Jin; Tao Tang; C. Zhou

    2003-01-01

    High quality single crystal gallium nitride nanowires (GaN NWs) are synthesized with a novel chemical vapor deposition (CVD) method. Transport studies of single crystal GaN nanowire devices exhibit n-type transistor behavior with high electron mobility. Ultraviolet (UV) light sensors are fabricated with GaN NW devices. The nanowire sensors exhibited a substantial increase in conductance upon UV light exposure. In addition

  1. Accurate Acoustic Thermometry I: The Triple Point of Gallium

    Microsoft Academic Search

    M R Moldover; J P M Trusler

    1988-01-01

    The speed of sound in argon has been accurately measured in the pressure range 25-380 kPa at the temperature of the triple point of gallium (Tg) and at 340 kPa at the temperature of the triple point of water (Tt). The results are combined with previously published thermodynamic and transport property data to obtain Tg = (302.9169 ± 0.0005) K

  2. Accurate Acoustic Thermometry I: The Triple Point of Gallium

    Microsoft Academic Search

    M. R. Moldover; J. P. M. Trusler

    1988-01-01

    The speed of sound in argon has been accurately measured in the pressure range 25-380 kPa at the temperature of the triple point of gallium (Tg) and at 340 kPa at the temperature of the triple point of water (Tt). The results are combined with previously published thermodynamic and transport property data to obtain Tg = (302.9169 +\\/- 0.0005) K

  3. INDIUM PHOSPHIDE WINDOW LAYERS FOR INDIUM GALLIUM ARSENIDE SOLAR CELLS

    Microsoft Academic Search

    Raj K. Jain

    Window layers help in reducing the surface recombination at the emitter surface of the solar cells re- sulting in significant improvement in energy conversion efficiency. Indium gallium arsenide (InxGa1-xAs) and related materials based solar cells are quite promising for photovoltaic and thermophotovoltaic applications. The flexibility of the change in the bandgap energy and the growth of InGaAs on different substrates

  4. A high open-circuit voltage gallium nitride betavoltaic microbattery

    Microsoft Academic Search

    Zaijun Cheng; Xuyuan Chen; Haisheng San; Zhihong Feng; Bo Liu

    2012-01-01

    A high open-circuit voltage betavoltaic microbattery based on a gallium nitride (GaN) p–i–n homojunction is demonstrated. As a beta-absorbing layer, the low electron concentration of the n-type GaN layer is achieved by the process of Fe compensation doping. Under the irradiation of a planar solid 63Ni source with activity of 0.5 mCi, the open-circuit voltage of the fabricated microbattery with

  5. Improved performance design of gallium arsenide solar cells for space

    Microsoft Academic Search

    R. H. Parekh; A. M. Barnett

    1984-01-01

    Two gallium arsenide solar cell configurations have evolved over the last decade--the heteroface solar cell which uses a (GaAl) as surface passivating layer over a p-n solar cell; and a n\\/sup +\\/-p-p\\/sup +\\/ shallow homojunction solar cell. Energy conversion efficiencies of 18.8 percent have been reported with the heteroface structure. In this paper, we report an improved design, shallow junction

  6. Fabrication of a gated gallium arsenide heterostructure resonant tunneling diode

    E-print Network

    Kinard, William Brian

    1989-01-01

    -dimensional confinement of i arriers in the potential ivell. Additionally, very interesting and unique transport phenomena are expected to emerge from further experimentation with the fabricated devices and other devices improved fr irii this technology. This thesis... removed organic material left by the previous solvent. The ivafers were then agitated in diluted hy- drochloric acid to remove any remaining metal contamination v, hile dissolving anv native gallium oxide on the surface. The &vafcrs were then rinsed...

  7. Deprotecting Thioacetyl-Terminated Terphenyldithiol for Assembly on Gallium Arsenide

    Microsoft Academic Search

    Dmitry A. Krapchetov; Hong Ma; Alex K. Y. Jen; Daniel A. Fischer; Yueh-Lin Loo

    2008-01-01

    We characterize the assembly of terphenyldithiol (TPDT) on gallium arsenide (GaAs) from ethanol (EtOH) and tetrahydrofuran (THF) as a function of ammonium hydroxide (NH4OH) concentration. NH4OH facilitates the conversion of thioacetyl end groups of the TPDT precursor to thiolates in the assembly solution. The final structure of TPDT assembled on GaAs is sensitive not only to the assembly solvent but

  8. Use of Gallium-67 in the diagnosis of occult infections

    SciTech Connect

    Hoffer, P.B.

    1981-05-01

    The mechanism of Ga-67 citrates in the diagnosis of infection involves the rapid binding of gallium by transferrin. The Ga-67-transferrin complex gains access into inflammatory tissue to some extent through the leaky endothelium of vessels at sites of inflammation. In addition, Ga-67 binds to a limited extent to circulating neutrophils. Advances in imaging techniques using Ga-67 citrates are discussed. The clinical applications include the diagnosis of bone and joint infections, pulmonary lesions, and infections of the urinary tract.

  9. TUNABLE TERAHERTZ GENERATION IN QUASI-PHASEMATCHED GALLIUM ARSENIDE

    Microsoft Academic Search

    Joseph E. Schaar; Konstantin L. Vodopyanov; Martin M. Fejer

    Sources of electromagnetic radiation with terahertz (THz) frequencies have been actively investigated during the last decade for applications in imaging and spectroscopic sensors. Femtosecond optical pulses have been shown to efficiently generate THz waves in quasi-phasematched (QPM) gallium arsenide (GaAs) (1). In this work we demonstrate a picosecond system creating a near diffraction-limited THz source with 1 mW of average

  10. POLLUTION PREVENTION IN THE SEMICONDUCTOR INDUSTRY THROUGH RECOVERY AND RECYCLING OF GALLIUM AND ARSENIC FROM GAAS POLISHING WASTES

    EPA Science Inventory

    A process was developed for the recovery of both arsenic and gallium from gallium arsenide polishing wastes. The economics associated with the current disposal techniques utilizing ferric hydroxide precipitation dictate that sequential recovery of toxic arsenic and valuble galliu...

  11. Trace-element zonation in garnets from The Thumb: heating and melt infiltration below the Colorado Plateau

    NASA Astrophysics Data System (ADS)

    Smith, Douglas; Griffin, William L.; Ryan, Chris G.; Sie, Soey H.

    1991-03-01

    Proton microprobe (PIXE) analysis of garnet, pyroxene, and olivine for Zr, Y, Ga, Ge, Sr, Ni, Mn and Zn has been combined with electron-probe and petrographic analysis to interpret the histories of garnetperidotite xenoliths from the minette neck at The Thumb on the Colorado Plateau. Garnet in seven rocks contains 10 110 ppm Zr and 25 95 ppm Ni. Substantial parts of these ranges are preserved in single, zoned garnets (Zr, 25 90 ppm; Ni, 25 60 ppm). Pyroxene and olivine are more homogeneous and equilibrated more quickly than granet to changing temperatures and metasomatic fluxes. The distribution coefficient of Ti between pyroxene and garnet rims may be sufficiently sensitive to pressure to be used as a geobarometer. Zirconium and Ti appear to have behaved similarly during melt infiltration and diffusion within garnet. Nickel in garnet is a sensitive recorder of temperature. A temperature of 900° C or less calculated from Ni in the cores of large garnets in one rock is at least as cool as that calculated for the Archaean Kaapvaal craton at similar depth, and the low temperature may be due to cooling of the Plateau lithosphere by the subducted Farallon plate. The zonation of these garnets to Ni-enriched rims has been simulated numerically by heating 260° C at 0.02°/year, followed by overgrowth of a rim and short annealing. Garnet in another rock records a temperature decrease of about 70° C, but Ni is more homogeneous in garnets in the other five rocks. The diverse temperature histories are attributed to local melt-mantle interactions. Calculated pressures and temperatures of xenoliths from The Thumb form a grouping similar to those for high-temperature parts of inflected geotherms in other xenolith suites, and the similarity is evidence for both the reality and the transients nature of the calculated inflections. Garnet that is zoned in Zr, Y, Ti and other elements preserves evidences for grain growth in response to melt infiltration in four of seven rocks. The ranges of both major and trace elements in the xenolith suite may be due largely to enrichment processes following earlier depletion.

  12. Incorporation of Integral Fuel Burnable Absorbers Boron and Gadolinium into Zirconium-Alloy Fuel Clad Material

    Microsoft Academic Search

    K. Sridharan; T. J. Renk; E. J. Lahoda; M. L Corradini

    2004-01-01

    Long-lived fuels require the use of higher enrichments of 235U or other fissile materials. Such high levels of fissile material lead to excessive fuel activity at the beginning of life. To counteract this excessive activity, integral fuel burnable absorbers (IFBA) are added to some rods in the fuel assembly. The two commonly used IFBA elements are gadolinium, which is added

  13. Phase compositions in magnesium-rare earth alloys containing yttrium, gadolinium or dysprosium

    Microsoft Academic Search

    P. J. Apps; H. Karimzadeh; J. F. King; G. W. Lorimer

    2003-01-01

    Phase compositions have been investigated, using thin foil energy dispersive X-ray spectroscopy, in three magnesium-rare earth alloys, containing yttrium, gadolinium or dysprosium. Compositions are suggested for the as-cast eutectic and ? precipitate phases and possible compositions for the ?1 precipitate phases are discussed.

  14. Chemically-induced stresses in gadolinium-doped ceria solid oxide fuel cell electrolytes

    Microsoft Academic Search

    A. Atkinson

    1997-01-01

    Cerium oxide doped with gadolinium is an attractive electrolyte material for solid oxide fuel cells (SOFCs) operating in the temperature range 500–800 °C. Under the low oxygen activity conditions of the SOFC anode the ceria is partially reduced and its lattice parameter increases leading to the generation of stress in the electrolyte. These stresses have been calculated for a range

  15. Gadolinium-Enhanced MR Imaging in the Evaluation of Uterine Fibroids Treated with Uterine Artery Embolization

    Microsoft Academic Search

    Tetsuya Katsumori; Kazuhiro Nakajima; Mitsukuni Tokuhiro

    OBJECTIVE . The purpose of this study was to determine whether tumor volume reduc- tion can be predicted by the infarction rate of uterine fibroids as seen on gadolinium-enhanced MR images obtained immediately after uterine artery embolization. MATERIALS AND METHODS . In our study, 36 women with symptomatic uterine fi- broids successfully underwent uterine artery embolization. Unenhanced and enhanced MR

  16. Preparation of 152Gd targets from a small quantity of gadolinium oxide in a pyrochemical reaction

    NASA Astrophysics Data System (ADS)

    Lipski, A. R.

    1995-02-01

    A simple method utilizing small amounts (< 5 mg) of isotopically enriched material for the production of gadolinium targets is discussed. An electrostatically focused e-gun is used in the procedure in which 152Gd 2O 3 powder undergoes reduction-distillation and deposition onto an Fe foil.

  17. A polymeric fastener can easily functionalize liposome surfaces with gadolinium for enhanced magnetic resonance imaging.

    PubMed

    Smith, Cartney E; Shkumatov, Artem; Withers, Sarah G; Yang, Binxia; Glockner, James F; Misra, Sanjay; Roy, Edward J; Wong, Chun-Ho; Zimmerman, Steven C; Kong, Hyunjoon

    2013-11-26

    Common methods of loading magnetic resonance imaging (MRI) contrast agents into nanoparticles often suffer from challenges related to particle formation, complex chemical modification/purification steps, and reduced contrast efficiency. This study presents a simple, yet advanced process to address these issues by loading gadolinium, an MRI contrast agent, exclusively on a liposome surface using a polymeric fastener. The fastener, so named for its ability to physically link the two functional components together, consisted of chitosan substituted with diethylenetriaminepentaacetic acid (DTPA) to chelate gadolinium, as well as octadecyl chains to stabilize the modified chitosan on the liposome surface. The assembly strategy, mimicking the mechanisms by which viruses and proteins naturally anchor to a cell, provided greater T1 relaxivity than liposomes loaded with gadolinium in both the interior and outer leaflet. Gadolinium-coated liposomes were ultimately evaluated in vivo using murine ischemia models to highlight the diagnostic capability of the system. Taken together, this process decouples particle assembly and functionalization and, therefore, has considerable potential to enhance imaging quality while alleviating many of the difficulties associated with multifunctional particle fabrication. PMID:24083377

  18. Spinal epidural abscess with gadolinium-enhanced MRI: serial follow-up studies and clinical correlations

    Microsoft Academic Search

    N. Sadato; Y. Numaguchi; D. Rigamonti; T. Kodama; E. Nussbaum; S. Sato; M. Rothman

    1994-01-01

    We reviewed serial MRI with and without gadolinium-DTPA in eight patients with spinal epidural abscess and correlated the findings and the clinical manifestations. In four patients, diffuse abscesses spanned four vertebral bodies or more; the others had focal abscesses associated with osteomyelitis and\\/or diskitis. In three of the four patients with diffuse abscesses, MRI (NCMRI) showed diffuse encasement of the

  19. Porphyrin-containing polyaspartamide gadolinium complexes as potential magnetic resonance imaging contrast agents.

    PubMed

    Yan, Guo-Ping; Li, Zhen; Xu, Wei; Zhou, Cheng-Kai; Yang, Lian; Zhang, Qiao; Li, Liang; Liu, Fan; Han, Lin; Ge, Yuan-Xing; Guo, Jun-Fang

    2011-04-01

    Porphyrin-containing polyaspartamide ligands (APTSPP-PHEA-DTPA) were synthesized by the incorporation of diethylenetriaminepentaacetic acid (DTPA) and 5-(4'-aminophenyl)-10,15,20-tris(4'-sulfonatophenyl) porphyrin, trisodium salt (APTSPP) into poly-?,?-[N-(2-hydroxyethyl)-l-aspartamide] (PHEA). These ligands were further reacted with gadolinium chloride to produce macromolecule-gadolinium complexes (APTSPP-PHEA-DTPA-Gd). Experimental data of (1)H NMR, IR, UV and elemental analysis evidenced the formation of the polyaspartamide ligands and gadolinium complexes. In vitro and in vivo property tests indicated that APTSPP-PHEA-DTPA-Gd possessed noticeably higher relaxation effectiveness, less toxicity to HeLa cells, and significantly higher enhanced signal intensities (SI) of the VX2 carcinoma in rabbits with lower injection dose requirement than that of Gd-DTPA. Moreover, APTSPP-PHEA-DTPA-Gd was found to greatly enhance the contrast of MR images of the VX2 carcinoma, providing prolonged intravascular duration, and distinguished the VX2 carcinoma and normal tissues in rabbits according to MR image signal enhancements. These porphyrin-containing polyaspartamide gadolinium complexes can be used as the candidates of contrast agents for targeted MRI to tumors. PMID:21272626

  20. Gadolinium-DOTA enhanced MRI of painful osseous crises in children with sickle cell anemia

    Microsoft Academic Search

    V. Bonnerot; G. Sebag; M. de Montalembert; M. Wioland; C. Glorion; R. Girot; D. Lallemand

    1994-01-01

    In order to evaluate the role of gadolinium-DOTA enhanced MRI in the management of painful osseous crises in children with sickle cell anemia (SCA), nine children with SCA underwent MRI, bone scans and ultrasonographic studies during 11 osseous crises. Imaging findings were compared with the final diagnosis: three acute osteomyelitis (AO) and 16 acute infarcts (AI). MRI could not differentiate

  1. Magnetocrystalline Anisotropy of Rare Earth Impurities Doped in Gadolinium. I. Heavy Rare Earth

    Microsoft Academic Search

    Keisuke Tajima

    1971-01-01

    The magnetocrystalline anisotropy of the heavy rare earth impurities doped in gadolinium metal was measured by a torque method in a temperature range from 4.2°K to about 200°K. The large contribution from the heavy rare earth impurities to the anisotropy is well explained by the crystal field theory. The temperature dependence of the anisotropy constant can be explained fairly well

  2. A new biodegradable and biocompatible gadolinium (III) -polymer for liver magnetic resonance imaging contrast agent.

    PubMed

    Xiao, Yan; Xue, Rong; You, Tianyan; Li, Xiaojing; Pei, Fengkui

    2015-07-01

    A new biodegradable and biocompatible gadolinium (III) -copolymer (ACL-A2-DOTA-Gd) has been developed as a potential liver magnetic resonance imaging (MRI) contrast agent. ACL-A2-DOTA-Gd consisted of a poly (aspartic acid-co-leucine) unit bound with 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid-gadolinium (Gd-DOTA) via the linkage of ethylenediamine. In vitro, the biodegradable experiment and cytotoxicity assay showed the biodegradability and biocompatibility of this gadolinium-polymer. ACL-A2-DOTA-Gd presented an increase in relaxivity of 2.4 times than the clinical Gd-DOTA. In vivo, gadolinium (III)-copolymer was mainly accumulated in the liver, and it could be excreted via the renal and hepatobiliary mechanism. The average enhancement of ACL-A2-DOTA-Gd (60.71±5.93%, 50-80min) in liver was 2.62-fold greater than that of Gd-DOTA (23.16±3.55%, 10-30min). ACL-A2-DOTA-Gd could be as a potential liver MRI contrast agent with a long time-window. PMID:25839395

  3. Are gadolinium-based contrast media nephrotoxic? A renal biopsy study.

    PubMed

    Akgun, Hulya; Gonlusen, Gulfiliz; Cartwright, Joiner; Suki, Wadi N; Truong, Luan D

    2006-09-01

    Gadolinium-based contrast media were originally introduced as alternatives to iodinated media for magnetic resonance imaging. Although originally thought to be nonnephrotoxic, gadolinium-based contrast media have recently been reported to be associated with acute renal failure; the mechanism and the underlying renal injury are not completely understood. We report what is, to our knowledge, the first renal biopsy in this context. A 56-year-old patient underwent 2 consecutive vascular imaging procedures in conjunction with gadolinium-based contrast medium administration. A few days later, the patient developed acute renal failure. A renal biopsy showed acute tubular cell injury including patchy tubular cell necrosis, tubular cell degeneration, and marked proliferation of tubular cells, together with mild interstitial edema and interstitial inflammation, but without significant glomerular or vascular changes. During supportive therapy, renal function was partially regained. This case emphasizes the potential nephrotoxicity of gadolinium-based contrast media and suggests that the nephrotoxicity is related to potentially reversible acute tubular cell injury. PMID:16948524

  4. Internalization pathways into cancer cells of gadolinium-based radiosensitizing nanoparticles Wael Rima a

    E-print Network

    Boyer, Edmond

    Internalization pathways into cancer cells of gadolinium-based radiosensitizing nanoparticles Wael Rima a , Lucie , Michèle Cottier g , Stéphane Roux h , Claire Rodriguez-Lafrasse c , Pascal Perriat a, * a INSA Nationale Supérieure des Mines de Saint-Etienne, CIS-EMSE, LINA EA 4624, F-42023 Saint-Etienne, France g

  5. Complexation of gadolinium(III) ions on top of nanometre-sized magnetoliposomes

    Microsoft Academic Search

    Stefaan J. H. Soenen; Linda Desender; Marcel De Cuyper

    2007-01-01

    The complex of diethylenetriaminepentaacetate (DTPA) with the paramagnetic gadolinium ion [Gd(III)] is a well-known blood pool contrast agent for magnetic resonance imaging (MRI). To obtain MRI pictures from other anatomical structures, for instance from tissues containing cells with phagocytic activity, larger colloidal complexes have to be constructed. Therefore, in view of modifying the physiological behaviour, the DTPA chelate was first

  6. Appraisal of lupus nephritis by renal imaging with gallium-67

    SciTech Connect

    Bakir, A.A.; Lopez-Majano, V.; Hryhorczuk, D.O.; Rhee, H.L.; Dunea, G.

    1985-08-01

    To assess the activity of lupus nephritis, 43 patients with systemic lupus erythematosus (SLE) were studied by gallium imaging. Delayed renal visualization 48 hours after the gallium injection, a positive result, was noted in 25 of 48 scans. Active renal disease was defined by the presence of hematuria, pyuria (10 or more red blood cells or white blood cells per high-power field), proteinuria (1 g or more per 24 hours), a rising serum creatinine level, or a recent biopsy specimen showing proliferative and/or necrotizing lesions involving more than 20 percent of glomeruli. Renal disease was active in 18 instances, inactive in 23, and undetermined in seven (a total of 48 scans). Sixteen of the 18 scans (89 percent) in patients with active renal disease showed positive findings, as compared with only four of 23 scans (17 percent) in patients with inactive renal disease (p less than 0.001). Patients with positive scanning results had a higher rate of hypertension (p = 0.02), nephrotic proteinuria (p = 0.01), and progressive renal failure (p = 0.02). Mild mesangial nephritis (World Health Organization classes I and II) was noted only in the patients with negative scanning results (p = 0.02) who, however, showed a higher incidence of severe extrarenal SLE (p = 0.04). It is concluded that gallium imaging is a useful tool in evaluating the activity of lupus nephritis.

  7. Defects in gallium nitride nanowires: first principles calculations

    SciTech Connect

    Wang, Zhiguo; Li, Jingbo; Gao, Fei; Weber, William J.

    2010-08-15

    Atomic configurations and formation energies of native defects in an unsaturated GaN nanowire grown along the [001] direction and with (100) lateral facets are studied using large-scale ab initio calculation. Cation and anion vacancies, antisites and interstitials in the neutral charge state are all considered. The nitrogen related defects are more stable than the gallium related defects under nitrogen-rich conditions. The configurations of these defects in the core region of the nanowire are same as those in the bulk GaN. The relaxation of vacancies is generally small, but the relaxation around antisite defects is large. The nitrogen interstitial relaxes into a split interstitial configuration. The configurations of the defects in the outermost free surface region are different than those in the core. A Ga atom on the outmost surface is replaced by a Ga interstital, and is ejected on to the surface to become an adsorbed atom. A gallium atom at the outermost surface can also be ejected out to become an adsorbed atom. Nitrogen interstitials form a split-interstitial configuration with one of the nearest-neighbor nitrogens. For a Ga vacancy at the edge of the side plane of the nanowire, nitrogen atom at a gallium site and nitrogen interstitial often induced the formation of N2 molecules with low formation energy, which agrees well with experiment findings [Nano Letters 9, 1844 (2009)].

  8. Ancient mantle metasomatism recorded in subcalcic garnet xenocrysts: Temporal links between mantle metasomatism, diamond growth and crustal tectonomagmatism

    NASA Astrophysics Data System (ADS)

    Shu, Qiao; Brey, Gerhard P.

    2015-05-01

    We have identified carbonatitic melts as the main agent for metasomatism in cpx-free garnet harzburgites from the Kaapvaal craton. Substantial overlap of the Ti/Eu and Zr/Hf ratios of subcalcic garnets from xenoliths and garnet inclusions in diamonds corroborate previous findings that mantle metasomatism and the growth of diamonds are connected processes. The key process involves the interaction of a carbonatitic melt with depleted garnet harzburgite leading to dissolution and regrowth of the constituent minerals and the growth of diamonds by redox reactions. Model calculations show that only small amounts of a carbonatite melt, between 0.3 to 3%, are needed to generate the range of sinusoidal Rare Earth Element patterns in the garnets from harzburgites and the inclusions in diamonds. The ?Hf values of the xenolith garnets range from extremely positive (?+1000) to extremely negative values (-65) with accompanying ?Nd values varying from +38 to -41. It can be shown that the negative ?Hf and ?Nd values correspond to the initial ratios of the metasomatizing agent. They can only stem from a very old (early Archean or Hadean) crustal component. Very negative ?Nd values have been found previously in subcalcic garnets from xenoliths and inclusions in diamonds. They yield early Archean model ages for the growth of diamonds. In these studies, very high, unsupported 87Sr/86Sr ratios were found as well. The combined evidence suggests that the metasomatic agents are derived from an old source with a high Rb/Sr ratio, typical for pelitic crustal rocks. Metasomatism in the mantle, the formation of diamonds and tectonomagmatic events in the crust occurred contemporaneously at least within the time span between the early Archean and the middle Proterozoic as can be seen from the comparison of crustal ages, Lu-Hf isochron ages from subcalcic garnets and Sm-Nd and Re-Os ages of inclusions in diamonds.

  9. Trace-element zonation in garnets from The Thumb: heating and melt infiltration below the Colorado Plateau

    Microsoft Academic Search

    Douglas Smith; William L. Griffin; Chris G. Ryan; Soey H. Sie

    1991-01-01

    Proton microprobe (PIXE) analysis of garnet, pyroxene, and olivine for Zr, Y, Ga, Ge, Sr, Ni, Mn and Zn has been combined\\u000a with electron-probe and petrographic analysis to interpret the histories of garnetperidotite xenoliths from the minette neck\\u000a at The Thumb on the Colorado Plateau. Garnet in seven rocks contains 10–110 ppm Zr and 25–95 ppm Ni. Substantial parts of

  10. Magmatic evolution of the suqii-wagga garnet-bearing two-mica granite, wallagga area, western Ethiopia

    Microsoft Academic Search

    T. Kebede; C. Koeberl; F. Koller

    2001-01-01

    The Suqii-Wagga two-mica granite, situated in the western Ethiopian Precambrian, is emplaced in a high-grade migmatitic terrane. It is composed of feldspars + quartz + muscovite + biotite ± garnet + zircon ± allanite ± apatite + Fe-Ti oxides + Fe sulphide. Textural studies and microprobe analyses revealed two generations of almandine-spessartine-rich magmatic garnet. The first is euhedral, fine-grained (300–350

  11. Garnet-perovskite transformation in CaGeO3 - In-situ X-ray measurements using synchrotron radiation

    Microsoft Academic Search

    J. Susaki; S. Akimoto; M. Akaogi; O. Shimomura

    1985-01-01

    The garnet-perovskite phase transformation in CaGeO3 was investigated in the pressure-temperature region to 6.5 GPa and 1200 C, using a cubic anvil type of high-pressure apparatus combined with synchrotron radiation. In-situ measurements with an energy dispersive X-ray diffraction system enable us to carry out dynamical observation of the transformation. The equilibrium phase boundary between the garnet and perovskite phases was

  12. Pollution prevention in the semiconductor industry through recovery and recycling of gallium and arsenic from GaAs polishing wastes

    Microsoft Academic Search

    J. A. Sturgill; J. T. Swartzbaugh; P. M. Randall

    2000-01-01

    A process was developed for the recovery of both arsenic and gallium from gallium arsenide polishing wastes. The economics\\u000a associated with the current disposal techniques utilizing ferric hydroxide precipitation dictate that sequential recovery\\u000a of toxic arsenic and valuable gallium, with subsequent purification and in-house reuse of both, is to the benefit of the gallium\\u000a arsenide crystal grower. The developed process

  13. High Sensitivity of Late Gadolinium Enhancement for Predicting Microscopic Myocardial Scarring in Biopsied Specimens in Hypertrophic Cardiomyopathy

    PubMed Central

    Konno, Tetsuo; Hayashi, Kenshi; Fujino, Noboru; Nagata, Yoji; Hodatsu, Akihiko; Masuta, Eiichi; Sakata, Kenji; Nakamura, Hiroyuki; Kawashiri, Masa-aki; Yamagishi, Masakazu

    2014-01-01

    Background Myocardial scarring can be assessed by cardiac magnetic resonance imaging with late gadolinium enhancement and by endomyocardial biopsy. However, accuracy of late gadolinium enhancement for predicting microscopic myocardial scarring in biopsied specimens remains unknown in hypertrophic cardiomyopathy. We investigated whether late gadolinium enhancement in the whole heart reflects microscopic myocardial scarring in the small biopsied specimens in hypertrophic cardiomyopathy. Methods and Results Twenty-one consecutive patients with hypertrophic cardiomyopathy who were examined both by cardiac magnetic resonance imaging and by endomyocardial biopsy were retrospectively studied. The right interventricular septum was the target site for endomyocardial biopsy in all patients. Late gadolinium enhancement in the ventricular septum had an excellent sensitivity (100%) with a low specificity (40%) for predicting microscopic myocardial scarring in biopsied specimens. The sensitivity of late gadolinium enhancement in the whole heart remained 100% with a specificity of 27% for predicting microscopic myocardial scarring in biopsied specimens. Quantitative assessments of fibrosis revealed that the extent of late gadolinium enhancement in the whole heart was the only independent variable related to the microscopic collagen fraction in biopsied specimens (? ?=? 0.59, 95% confident interval: 0.15 – 1.0, p ?=? 0.012). Conclusions Although there was a compromise in the specificity, the sensitivity of late gadolinium enhancement was excellent for prediction of microscopic myocardial scarring in hypertrophic cardiomyopathy. Moreover, the severity of late gadolinium enhancement was independently associated with the quantitative collagen fraction in biopsied specimens in hypertrophic cardiomyopathy. These findings indicate that late gadolinium enhancement can reflect both the presence and the extent of microscopic myocardial scarring in the small biopsied specimens in hypertrophic cardiomyopathy. PMID:25000555

  14. Gain-guided aluminum gallium arsenide-gallium arsenide quantum-well heterostructure lasers fabricated by hydrogenation

    Microsoft Academic Search

    1988-01-01

    New fabrication techniques that are simple and easily implemented with present technology may have an impact on laser manufacturing. Hydrogenation is such a process. Hydrogen compensation of shallow impurities is studied in aluminum gallium arsenide. Data are presented showing the effects of exposure to a hydrogen plasma on n-type GaAs and both n- and p-type Al{sub 0.75}Ga{sub 0.25}As. Samples are

  15. Site-selective spectroscopy of garnet crystals doped with chromium ions.

    PubMed

    Örücü, Hümeyra; Özen, Gönül; Di Bartolo, Baldassare; Collins, John

    2012-09-01

    Site-selective spectroscopy is a tool that can be used to uncover the presence of multiple sites available to optically active ions in host lattices. In this Article, we present techniques that can be applied to appraise the different sites that may occur in systems where charge compensation is required or in systems where such compensation is not present. We then consider some garnet crystals doped with chromium ions. For the Cr-doped garnets (YAG, GGG, GSGG, and CYMGG), we present luminescence and lifetime data over a wide temperature range, and infer not only the presence of different centers, but also the interaction among them as a function of temperature. PMID:22867053

  16. Geothermometry of garnet lherzolite nodules with special reference to those from the kimberlites of Northern Lesotho

    NASA Astrophysics Data System (ADS)

    Carswell, D. A.; Gibb, F. G. F.

    1980-12-01

    Different published geothermometric methods have been tested on a large suite of garnet lherzolite nodules from the kimberlites of Northern Lesotho. Comparison of the various calculated equilibration temperature estimates indicates that several of these methods yield unreliable results and should therefore be rejected. However, there is little to choose between the values obtained from five other methods based on three different element exchange reactions. Accordingly we conclude that the petrogenesis of garnet lherzolite nodules is best discussed with reference to the mean temperature estimates derived from these five preferred methods. The late Cretaceous palaeogeotherm for Northern Lesotho is revised on this basis and found to be of a similar form to previous estimates but is significantly displaced to higher temperatures.

  17. Determining P-T paths from garnet zoning using a brute-force computational method

    NASA Astrophysics Data System (ADS)

    Vrijmoed, J. C.; Hacker, B. R.

    2014-04-01

    Reconstructing metamorphic pressure-temperature ( P- T) paths through petrographic textures, mineral assemblages, and compositions is fundamental to the understanding of orogenesis. We present a new method to derive the P- T path of a rock from mineral zoning. Using Perple_X (Connolly in Earth Planet Sci Lett 236(1-2):524-541, 2005) and a M atlab script, we forward model garnet zoning, parageneses, and mineral modes for an arbitrary set of possible P- T paths, and then compare the calculated results to mineral modes, textures, and zoning preserved in rocks. The best-fit P- T path is determined by comparing the calculated zoning to the measured zoning using the sum of squares. The results indicate that combining Mg#, Ca, and Mn zoning in garnet with mineral modes can yield precise constraints on the P- T path of a rock.

  18. The Role of Garnet Pyroxenite in High-Fe Mantle Melt Generation: High Pressure Melting Experiments

    NASA Astrophysics Data System (ADS)

    Tuff, J.; Takahashi, E.; Gibson, S.

    2004-12-01

    Evidence for the existence of heterogeneous or 'marble cake' convecting mantle1 is provided recently by rare, high MgO ( ˜ 15 wt.%) primitive magmas with anomalously high abundances of FeO* ( ˜ 13.5 to 16 wt. %2,3; where FeO* = total Fe as FeO). These high-Fe mantle melts show a limited occurrence in the initial stage of magmatism in large igneous provinces (e.g. Deccan, Ethiopia and Paraná-Etendeka) and some have incompatible trace-element and radiogenic-isotopic ratios (Sr, Nd and Pb) that resemble those of ocean-island basalts. This suggests that they are predominantly derived from the convecting mantle2. The ferropicrites are mildly- to sub-alkaline and have low contents of Al2O3 (< 10 wt.%) and heavy rare-earth elements (e.g. Lu < 0.18ppm) that are consistent with the increased stability of garnet, due to the high FeO* content in the ferropicrite mantle source. It has been proposed that the source of the high FeO* may be garnet-pyroxenite streaks derived from subducted mafic oceanic crust2. We have undertaken melting experiments between 1 atmosphere and 7 GPa in order to determine the anhydrous phase relations of an uncontaminated ferropicrite lava from the base of the Early-Cretaceous Paraná-Etendeka continental flood-basalt province. The sample has high contents of MgO ( ˜ 14.9 wt.%), FeO* (14.9 wt.%) and NiO (0.07 wt.%). Olivine phenocrysts have maximum Fo contents of 85 and are in equilibrium with the host rock, assuming a Kd of 0.32 and we believe that the sample is representative of a primary Fe-rich mantle plume derived melt. In total, 75 experimental runs were carried out. Melting phase relations as well as compositions and modal proportions of all coexisting phases were successfully determined in 60 run products. Phase relations indicate that the ferropicrite melt was generated either at ˜ 2.2 GPa from an olivine-pyroxene residue or ˜ 5 GPa from a garnet-pyroxene residue. A low bulk-rock Al2O3 content (9 wt.%) and high [Gd/Yb]n ratio (3.1) are consistent with residual garnet in the ferropicrite melt source and favour high-pressure melting of garnet-pyroxenite. The garnet pyroxenite may represent subducted oceanic lithosphere entrained by the upwelling Tristan mantle plume starting-head. During adiabatic decompression, intersection of the garnet pyroxenite solidus at ˜ 5 GPa would occur at mantle potential temperatures of ˜ 1550° C. Subsequent melting of peridotite at ˜ 4.5 GPa may be restricted by the thick overlying sub-continental lithosphere such that dilution of the garnet-pyroxenite component would be significantly less than in intra-plate oceanic settings. This model accounts for the limited occurrence of ferropicrite magma in the initial stage of continental large igneous provinces and its absence in ocean-island basalt successions. 1 Allègre et al., Philosophical Transactions of the Royal Society of London A297, 447-477 (1980). 2 Gibson et al., Earth and Planetary Science Letters 174, 355-374 (2000). 3 Gibson, Earth and Planetary Science Letters 195, 59-74 (2002).

  19. Magnetic anisotropies in (210)-oriented bismuth substituted iron garnet thin films

    NASA Astrophysics Data System (ADS)

    Nistor, I.; Holthaus, C.; Tkachuk, S.; Mayergoyz, I. D.; Krafft, C.

    2007-05-01

    The liquid phase epitaxy growth and characterization of single crystal (210)-oriented thin garnet films with Bi substitution up to 1.5at./f.u. is reported. These epitaxial films exhibit an easy plane of magnetization which is inclined with respect to the film plane, making them uniquely suitable for garnet-based magneto-optic imagers (MOIs). In order to identify the optimal growth conditions to attain the highest sensitivity of such MOIs, the chemical composition of the films is discussed in relation with their magnetic and optic properties. It has been demonstrated that the increase in the amount of Pr tends to increase the in-plane orthorhombic anisotropy field HKi, while the rare-earth substitution by Bi has a strong effect on the canted orthorhombic anisotropy Kyz. The best MOI film had a saturation field of 130Oe and a sensitivity of 175deg /A.

  20. Zintl cluster chemistry in the alkali-metal-gallium systems

    SciTech Connect

    Henning, R.

    1998-03-27

    Previous research into the alkali-metal-gallium systems has revealed a large variety of networked gallium deltahedra. The clusters are analogues to borane clusters and follow the same electronic requirements of 2n+2 skeletal electrons for closo-deltahedra. This work has focused on compounds that do not follow the typical electron counting rules. The first isolated gallium cluster was found in Cs{sub 8}Ga{sub 11}. The geometry of the Ga{sub 11}{sup 7{minus}} unit is not deltahedral but can be described as a penta-capped trigonal prism. The reduction of the charge from a closo-Ga{sub 11}{sup 13{minus}} to Ga{sub 11}{sup 7{minus}} is believed to be the driving force of the distortion. The compound is paramagnetic because of an extra electron but incorporation of a halide atom into the structure captures the unpaired electron and forms a diamagnetic compound. A second isolated cluster has been found in Na{sub 10}Ga{sub 10}Ni where the tetra-capped trigonal prismatic gallium is centered by nickel. Stabilization of the cluster occurs through Ni-Ga bonding. A simple two-dimensional network occurs in the binary K{sub 2}Ga{sub 3} Octahedra are connected through four waist atoms to form a layered structure with the potassium atoms sitting between the layers. Na{sub 30.5}Ga{sub 60{minus}x}Ag{sub x} is nonstoichiometric and needs only a small amount of silver to form (x {approximately} 2--6). The structure is composed of three different clusters which are interconnected to form a three-dimensional structure. The RbGa{sub 3{minus}x}Au{sub x} system is also nonstoichiometric with a three-dimensional structure composed of Ga{sub 8} dodecahedra and four-bonded gallium atoms. Unlike Na{sub 30.5}Ga{sub 60{minus}x}Ag{sub x}, the RbGa{sub 3} binary is also stable. The binary is formally a Zintl phase but the ternary is not. Some chemistry in the alkali-metal-indium system also has been explored. A new potassium-indium binary is discussed but the structure has not been completely characterized.

  1. Compression of Ferromagnesian Garnets and the Effect of solid solutions on the Bulk Modulus

    Microsoft Academic Search

    Taro Takahashi; Lin-Gun Liu

    1970-01-01

    The effect of pressure on the lattice parameter, hence the molar volume, of four ferromagnesian garnet specimens was determined up to 328 kb at room temperature by means of the X-ray diffraction technique employing a diamond-anvil high-pressure cell. Using a BirchMurnaghan equation with a (OK\\/OP) value of 5.45, the isothermal bulk modulus at zero pressure Ko has been computed to

  2. Botanical trash analysis of raw materials used in the cotton garnetting industry

    Microsoft Academic Search

    P. R. MOREY

    1979-01-01

    The botanical nature of the trash in raw materials and batting from 5 cotton garnetting plants was compared with that present in raw cottons utilized by cotton yarn manufacturers. Linters processed by garnetters contained less (0.11%) leaflike (cotton bract, cotton leaf, and weed leaf) trash than that found in raw cottons (0.45–1.79%). The amount of leaflike trash present in soft

  3. Anisothermal reaction synthesis of garnets, ferrites, and spinels in microwave field

    Microsoft Academic Search

    Ramesh D. Peelamedu; Rustum Roy; Dinesh Agrawal

    2001-01-01

    The experimental achievement of reacting two phases that are held at two different temperatures—the anisothermal reaction condition—is a radical innovation in materials chemistry. Details on the synthesis of Yttrium Iron Garnet (Y3Fe5O12), Barium Ferrite (BaFe12O19), and Nickel Aluminate (NiAl2O4) in 1–10 min in a microwave field are provided. The starting precursor oxides were chosen such that they include a low

  4. Thickness and temperature dependence of subsidiary absorption thresholds in yttrium-iron-garnet thin films

    Microsoft Academic Search

    A. V. Pomyalov; I. Laulicht; J. Barak

    1993-01-01

    The microwave subsidiary absorption threshold in tangentially magnetized yttrium-iron-garnet (YIG) films was measured as a function of the static magnetic field, film thickness and decrease in the 0.3-3 mum range is observed. The effect is explained quantitatively by using modified Damon-Eshbach dispersion relations which take into account exchange interactions. The effect of temperature on hcrit, the smallest threshold field amplitude,

  5. A study on the effect factors of sol-gel synthesis of yttrium aluminum garnet nanopowders

    Microsoft Academic Search

    Lin Yang; Tiecheng Lu; Hui Xu; Wei Zhang; Benyuan Ma

    2010-01-01

    Yttrium aluminum garnet (YAG) nanopowders were synthesized by sol-gel method using aluminum nitrate, yttrium nitrate, and citric acid as starting materials, de-ionized water, ethanol, and ethylene glycol as solvents, respectively. The phase formation process, state of particle size distribution (PSD), compositions, morphological characteristics, and thermal behavior of the powders were investigated by means of x-ray diffractometry, PSD, Fourier transform infrared,

  6. Development of Novel Garnet-Type Solid Electrolytes for Potential Application in Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Narayanan, Sumaletha

    The development of promising solid electrolytes having a garnet-like structure has been successfully achieved through solid state (ceramic) method. Various approaches to improve the Li ion conductivity were employed. The first approach involved creating oxide ion vacancies into the crystal structure of parent garnet-like oxide, Li5La3Nb2O 12 to create a novel family of compounds with nominal composition, Li 5La3Nb2-xYxO12-? (0 ? x ? 1). The second approach was Li stuffing into the garnet-like oxides to develop a series of Li stuffed novel Li5+2xLa3Nb 2-xYxO12 (0.05 ? x ? 0.75) and Li6.5 La2.5Ba0.5ZrTaO12. Powder X-ray diffraction (PXRD), thermo gravimetric analysis (TGA), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) coupled with a wavelength-dispersive spectrometer (WDS), 7Li nuclear magnetic resonance (Li-NMR), and AC impedance spectroscopy were employed to characterize the structure, morphology, elemental composition, Li ion sites, and Li ion conductivity. Studies have shown that Li5+2xLa 3Nb2-xYxO12 have turned out to be promising solid electrolytes with high Li ion conductivity (10-4 Scm -1 at ambient temperatures). In addition, all families of garnets are found to be chemically stable with Li cathode materials (Li2MMn 3O8, where M = Fe, Co) up to 400 °C in air. The developed electrolyte materials have the potential to be used in all-solid-state Li ion batteries.

  7. Specific heat anomaly of the holmium garnet Ho 3Al 5O 12 at low temperature

    Microsoft Academic Search

    Shoichi Nagata; Hiromi Sasaki; Kurando Suzuki; Junji Kiuchi; Nobuo Wada

    2001-01-01

    Specific heat of the garnet-type single crystals Ho3Al5O12 exhibits two sharp peaks at 0.839 and 0.220K. The antiferromagnetic transition occurs at 0.839K with ?-type specific heat anomaly, while the electric quadrupole order may be found at 0.220K in the insulating state without any conduction electrons. On the assumption that the influence of dominant cubic crystal field on 5I8 state for

  8. Mechanochemical solid reaction of yttrium oxide with alumina leading to the synthesis of yttrium aluminum garnet

    Microsoft Academic Search

    Qiwu Zhang; Fumio Saito

    2003-01-01

    Dry grinding of Y2O3 and transition aluminas was conducted, using a planetary ball mill under atmospheric conditions, to synthesize yttrium aluminum garnet (Y3Al5O12, YAG). The Y2O3 reacts mechanochemically with the transition aluminas to form YAlO3 and YAG after 120 min of grinding. No reaction occurs when the Y2O3 was ground with hard corundum or soft gibbsite. Grinding the Y2O3 for

  9. Growth of rare earth garnet crystals by the floating zone method

    Microsoft Academic Search

    S. Kimura; K. Kitamura; I. Shindo

    1983-01-01

    Characterization of rare earth garnet crystals grown by the floating zone method using convergent radiation heating is described. Y3Fe5O12 was studies mainly. The growth conditions influenced the shape of the solid-liquid interface and this as a consequence governed the quality of the grown crystals. It was shown that a slightly convex interface toward the liquid was desirable for growth of

  10. Excitation of magnetic precession in bismuth iron garnet via a polarization-independent impulsive photomagnetic effect

    NASA Astrophysics Data System (ADS)

    Koene, Benny; Deb, Marwan; Popova, Elena; Keller, Niels; Rasing, Theo; Kirilyuk, Andrei

    2015-05-01

    A polarization-independent, nonthermal optical effect on the magnetization in bismuth iron garnet is found, in addition to the circular polarization-dependent inverse Faraday effect and the linear polarization-dependent photoinduced magnetic anisotropy. Its impulsive character is demonstrated by the field dependence of the amplitude of the resulting precession, which cannot be explained by a long-living photo or heat-induced anisotropy.

  11. Garnet and tourmaline as provenance indicators of terrigenous material in epicontinental carbonates (Middle Triassic, S Poland)

    NASA Astrophysics Data System (ADS)

    Kowal-Linka, Monika; Stawikowski, Wojciech

    2013-06-01

    Heavy mineral grains contained in epicontinental carbonates are very rarely used for provenance analysis. This study deals with detrital heavy minerals separated from marly limestones and marlstones of the Gogolin Formation (GF; Middle Triassic), S Poland, to determine their source rocks and alimentary areas. The GF carbonates typically contain ? 1 wt.% of heavy minerals within the very fine sand fraction. The heavy mineral assemblages consist predominantly of garnets (53.0-92.2%), and tourmalines (3.8-30.4%). EPMA analyses reveal four groups of garnets: low-Grs almandines with 30-50 mol% Prp, almandines with 20-35 mol% Prp and up to 35 mol% Grs, almandines with up to 20 mol% Sps, and rare pyrope grains (~ 60 mol% Prp). The composition of the garnets indicates that HP felsic granulites were their main source rocks, but more mafic HP rocks (eclogites, retrograded eclogites, and mafic granulites), gneisses, mica schists, and garnet peridotites also contributed. The detrital tourmalines are represented mainly by dravite, and less frequently by schorl, which were derived mostly from paragneisses and mica schists, and in minor part from granitoids and pegmatites. The E-NE part of the Bohemian Massif is the most probable location of the source rocks. The presumed source rocks presently outcrop in the Moldanubian Zone, the Kutná Hora Unit, the Svratka Unit, and the Góry Sowie Massif. Nowadays, the bodies formed by the HP rocks within these units are insufficiently large to act as sources for delivering detrital material in the determined proportions. The high content of HP metamorphic grains thus indicates the past existence of extensively exposed and abundant high-pressure metamorphic rocks, eroded during and/or after the Middle Triassic.

  12. Fe-Mn partitioning between garnet and ilmenite: experimental calibration and applications

    Microsoft Academic Search

    Mark I. Pownceby; Victor J. Wall; Hugh St. C. O'Neill

    1987-01-01

    A new mineralogic geothermometer based on the partitioning of Fe and Mn between garnet and ilmenite has been calibrated by reversal experiments in the P-T range 600 900° C, 2 and 5 kbars and for fO2=QFM. The results constitute a sensitive geothermometer applicable over a broad range of composition and conditions. Garnetilmenite thermometry has advantages relative to existing geothermometers because

  13. Plant trash in linters and willowed picker: materials used in the cotton garnetting industry.

    PubMed

    Morey, P R; Wakelyn, J P

    1976-07-01

    First cut linters and willowed picker, used in cotton garnetting, were examined for content of cotton bract an other plant trash. Bract was found to be a minimal contaminant of the trash of first cut linters. A significant amount of bract (about 9% of the trash) was present in willowed picker. Cotton seed hulls, a valuable oil mill by product, contained an insignificant amount of bract trash. PMID:961599

  14. Dating high-grade metamorphism: constraints from zircon and garnet REE compositions

    Microsoft Academic Search

    M. J. Whitehouse; J. P. Platt

    2001-01-01

    We present high spatial resolution ion microprobe REE analyses of zircon and garnet from pelitic granulite adjacent to the Ronda peridotite, Betic Cordillera, southern Spain. The zircons exhibit polyphase growth, with thick structureless (in cathodoluminescence) overgrowths over detrital cores. These overgrowths yield a U-Pb age of 21.3 +\\/- 0.3 Ma [1, unpublished data] which we intepret as dating an episode

  15. Different Sintering Routes for Preparing Alumina-Yttrium Aluminum Garnet Nanocomposites

    Microsoft Academic Search

    P. Palmero; C. Stella; A. Simone; C. Esnouf; G. Fantozzi; L. Montanaro

    2005-01-01

    Alumina-yttrium aluminum garnet (YAG) 50 vol % nanocomposite powders were prepared by a wet-chemical synthesis and characterized by simultaneous DTA-TG, XRD, and TEM analyses. Amorphous powders were preheated at four different temperatures (namely, 600, 800, 900, and 1215°C) on the basis of the previous characterization, and the influence of this thermal treatment on sintering behavior, final microstructure, and density was

  16. Orthorhombic perovskite phases observed in olivine, pyroxene and garnet at high pressures and temperatures

    Microsoft Academic Search

    Lin-Gun Liu

    1976-01-01

    Ferromagnesian silicate olivines, pyroxenes and garnets with Mg\\/(Mg + Fe)>~0.3 (molar) have been found to transform to high-pressure phases characterized by the orthorhombic perovskite structure when compressed to pressures above 250 kbar in a diamond-anvil press and heated to temperatures above 1,000°C with a YAG laser. The zero-pressure density of the perovskite phase of (Mg,Fe)SiO3 is about 3-4% greater than

  17. Magnetic-field sensors based on iron garnets with in-plane magnetization

    NASA Astrophysics Data System (ADS)

    Holthaus, C.; Nistor, I.; Mayergoyz, I. D.; Krafft, C.

    2006-04-01

    A magnetic-field sensor is proposed that uses thin garnet films with in-plane magnetization and strong magneto-optical activity. The advantages of this sensor are its high intrinsic sensitivity and the possibility of tailoring the field range for linear response. Measurements at 80 Hz yield noise-equivalent magnetic fields of 1.5 ?T/Hz and a signal-to-noise ratio of 68 dB.

  18. Fe-Mn partitioning between garnet and ilmenite: experimental calibration and applications

    Microsoft Academic Search

    Mark I. Pownceby; Victor J. Wall; Hugh St. C. O'Neill

    1987-01-01

    A new mineralogic geothermometer based on the partitioning of Fe and Mn between garnet and ilmenite has been calibrated by reversal experiments in the P-T range 600–900° C, 2 and 5 kbars and for fO2=QFM. The results constitute a sensitive geothermometer applicable over a broad range of composition and conditions. Garnetilmenite thermometry has advantages relative to existing geothermometers because of

  19. Raman spectroscopy of detrital garnet from the (U)HP terrane of eastern Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Andò, Sergio; Baldwin, Suzanne L.; Fitzgerald, Paul G.; Malusà, Marco G.; Aliatis, Irene; Vezzoli, Giovanni; Garzanti, Eduardo

    2013-04-01

    Garnet is one of the most widespread heavy minerals in sediments derived from orogenic systems. Its chemical composition varies systematically with temperature and pressure conditions, and thus provides information on the metamorphic evolution of source areas that is crucial in tectonic and geodynamic reconstructions. Garnet is easily identified in mineral grain mounts and is relatively stable during burial diagenesis. Raman spectroscopy allows rapid determination of garnet compositions in grain mounts or thin sections of sand and sandstone samples, and can be used to assess their density and chemical composition quite accurately ("MIRAGEM" method of Bersani et al., 2009; Andò et al., 2009). In the D'Entrecastreaux Islands of southeastern Papua New Guinea, the world's youngest (U)HP rocks are exposed. There, mafic rocks and their felsic host gneisses were metamorphosed under eclogite facies conditions from late Miocene to Pliocene, before being exhumed from depths of ~90 km (Baldwin et al., 2004, 2008). The eclogite preserves a peak assemblage of garnet, omphacite, rutile, phengite and Si02 (Hill and Baldwin, 1993). A coesite-eclogite has been found in one small island outcrop. In order to sample garnet populations representative of a larger geographical area, we sampled and studied a heavy-mineral-dominated placer sand (HMC 80) from a beach from SE Goodenough Island. Garnet grains in beach sand are associated with blue-green to subordinately green-brown amphibole and minor epidote, omphacitic clinopyroxene, titanite, apatite and rutile. The subordinate low-density fraction is feldspatho-quartzose with high-rank metamorphic rock fragments and biotite (Q62 F35 Lm2; MI 360). Detrital garnets are mostly classified as almandine with relatively high Mg and Ca and lacking Mn, typical of the eclogite facies (Win et al., 2007; type Ci garnets of Mange and Morton 2007; Andò et al., 2013). In well-described stratigraphic sequences within syn-and post-tectonic basins adjacent to orogenic systems, Raman-assisted heavy-mineral studies allow us to detect the first arrival of eclogitic garnet, and thus to assess the minimum age of exhumation and final unroofing of high-pressure rocks (Malusà et al., 2011; Malusà and Garzanti, 2012). However, in the (U)HP terrane of southeastern Papua New Guinea, sediments derived from the actively exhuming D'Entrecasteaux Island core complexes are still being deposited offshore, are rarely preserved sub-aerially, and as such stratigraphic constraints are limited. Raman analysis of detrital garnets from placer sand thus provides invaluable constraints to compare with mineral assemblages preserved in exhumed eclogites. REFERENCES Andò S., Bersani D., Vignola P., Garzanti E. 2009. Raman spectroscopy as an effective tool for high-resolution heavy-mineral analysis: Examples from major Himalayan and Alpine fluvio-deltaic systems. Spectrochim. Acta A73:450-455. Andò S., Morton A., Garzanti E. 2013. Metamorphic grade of source rocks revealed by chemical fingerprints of detrital amphibole and garnet. Geol. Soc. London Spec. Publ. Sediment Provenance Studies in Hydrocarbon Exploration & Production. Baldwin S.L., Monteleone B., Webb L.E., Fitzgerald P.G., Grove M., Hill E.J. 2004. Pliocene eclogite exhumation at plate tectonic rates in eastern Papua New Guinea. Nature 431:263-267. Baldwin S.L., Webb L.E., Monteleone B.D. 2008. Late Miocene coesite-eclogite exhumed in the Woodlark Rift. Geology 36:735-738 Bersani D., Andò S., Vignola P., Moltifiori G., Marino I.G., Lottici P.P., Diella V., 2009. Micro-Raman spectroscopy as a routine tool for garnet analysis. Spectrochim. Acta A73:484-491. Hill E.J., Baldwin S.L. 1993. Exhumation of high-pressure metamorphic rocks during crustal extension in the D'Entrecasteaux region, Papua New Guinea. J. Metam. Geol. 11:261-277. Malusà M.G., Faccenna C., Garzanti E., Polino R. 2011. Divergence in subduction zones and exhumation of high-pressure rocks (Eocene Western Alps). Earth Pl. Sci. Lett. 310:21-32. Malusà M.G., Garzanti E. 2012. Actualistic snapshot o

  20. Low temperature recombination and trapping analysis in high purity gallium arsenide by microwave photodielectric techniques

    NASA Technical Reports Server (NTRS)

    Khambaty, M. B.; Hartwig, W. H.

    1972-01-01

    Some physical theories pertinent to the measurement properties of gallium arsenide are presented and experimental data are analyzed. A model for explaining recombination and trapping high purity gallium arsenide, valid below 77 K is assembled from points made at various places and an appraisal is given of photodielectric techniques for material property studies.

  1. Synthesis and use of (polyfluoroaryl)fluoroanions of aluminum, gallium and indium

    DOEpatents

    Marks, Tobin J. (Evanston, IL); Chen, You-Xian (Midland, MI)

    2000-01-01

    Salts of (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are described. The (polyfluoroaryl)fluoroanions have the formula [ER'R"R'"F].sup..crclbar. wherein E is aluminum, gallium, or indium, wherein F is fluorine, and wherein R', R", and R'" is each a fluorinated phenyl, fluorinated biphenyl, or fluorinated polycyclic group.

  2. Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells

    E-print Network

    Rockett, Angus

    Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells O. Lundberga,*, J. Lua , A Abstract The diffusion of indium and gallium in polycrystalline thin film Cu(In,Ga)Se2 layers has been with energy dispersive X-ray spectroscopy. It was found that the grain boundary diffusion

  3. The development and implementation of industrial hydrometallurgical gallium recovery of the Clarksville Refinery waste residue

    NASA Astrophysics Data System (ADS)

    Fayram, Todd S.

    Todd Fayram, the Gordonsville Operation of Pasminco US Inc., and the Center for Advanced Mineral and Metallurgical Processing (CAMP) at Montana Tech studied, developed and implemented a pilot scale hydrometallurgical facility for the industrial recovery of gallium. This thesis describes the testing and engineering program that culminated in this successful recovery of gallium through process described herein.

  4. X-ray microscopy studies on the pharmaco-dynamics of therapeutic gallium in rat bones

    SciTech Connect

    Bockman, R.; Repo, M.; Warrell, R.; Pounds, J.G.; Kwiatek, W.M.; Long, G.J.; Schidlovksy, G.; Jones, K.W.

    1987-01-01

    We describe here our preliminary results on gallium and calcium quantitation and localization using x-ray microscopy techniques at the X-26 beam line of the National Synchrotron Light Source (NSLS) at 50 to 100 ..mu..m resolution and 10/sup )minus/6) gg detection levels. Since the original observation of exogenous gallium accumulation in bones, several studies have demonstrated that gallium nitrate is extremely effective in preserving boen mienral content both in vivo and in vitro. Gallium nitrate therapy normalized serum calcium levels in a study of patients with caner-related hypercalcemia, resistant to standard hydration and diuretic therapy. Recently, gallium nitrate treatment has been shown to halt the accelerated bone resorption that is frequently associated with cancers metastatic to bone. Several lines of evidence from vitro studies recently led to the demonstration of increased bone calcium and improvement in hydroxyapatite crystallinity in adult gallium-treated rats. Evidence is rapidly accumulating that gallium nitrate is an effective, new therapeutic agent for inhibition of accelerated bone resorption associated with cancer-related hypercalcemia. It has also been suggested that gallium could have wide clinical applications in disorders characterized by accelerated calcium loss from bone. 7 refs., 3 figs., 1 tab

  5. Realization of the triple points of gallium, water and mercury by an adiabatic calorimetric method

    Microsoft Academic Search

    H. Sakurai

    1996-01-01

    The triple points of water, mercury and gallium are realized, mainly for the calibration of capsule-type thermometers, by a calorimetric method using platinum cells for water and mercury, and a small glass cell for gallium. Their molar impurities are estimated from the relation between the melting temperatures and the inverses of the fraction of melt. Almost all the samples show

  6. Major and trace element chemistry and Sm–Nd age correlation of magmatic pegmatite garnet overprinted by eclogite-facies metamorphism

    Microsoft Academic Search

    G. Habler; M. Thöni; C. Miller

    2007-01-01

    Meta-pegmatites are widespread in the polymetamorphic Koralpe–Saualpe basement, an Austroalpine unit with eo-Alpine high-pressure overprint. Major and trace element data of coarse-grained garnet and equilibrium relationships with other pegmatite minerals indicate that garnet crystallized during pegmatite emplacement. Whole rock and garnet separates from the meta-pegmatites yield Sm–Nd isochrons with Late Permian–Early Triassic ages of 254±2–239±2 Ma. Surprisingly, the Cretaceous eclogite facies

  7. Crystal structure of synthetic Mg3Cr2Si3O12, the high-pressure Cr end-member of the knorringite-pyrope garnet series

    Microsoft Academic Search

    Amélie Juhin; Guillaume Morin; Eric Elkaim; Dan J Frost; Farid Juillot; Georges Calas

    2009-01-01

    Knorringite, the Cr-end-member of the pyrope garnet series (Nixon et al. 1968), often occur in high proportions in kimberlite garnets and is thus used for tracing high-pressure deep-earth conditions favorable to the formation of diamonds, in which knorringite-rich garnet can occur as inclusions. However, although the synthesis of knorringite is reported in the literature (Ringwood 1977; Irifune et al. 1982;

  8. Metasomatic Control of Water in Garnet and Pyroxene from Kaapvaal Craton Mantle Xenoliths

    NASA Technical Reports Server (NTRS)

    Peslier, Anne H.; Woodland, Alan B.; Bell, David R.; Lazarov, Marina; Lapen, Thomas J.

    2012-01-01

    Fourier transform infrared spectrometry (FTIR) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) were used to determine water, rare earth (REE), lithophile (LILE), and high field strength (HFSE) element contents in garnet and pyroxene from mantle xenoliths, Kaapvaal craton, southern Africa. Water enters these nominally anhydrous minerals as protons bonded to structural oxygen in lattice defects. Pyroxene water contents (150-400 ppm in clinopyroxene; 40-250 ppm in orthopyroxene) correlate with their Al, Fe, Ca and Na and are homogeneous within a mineral grains and a xenolith. Garnets from Jagersfontein are chemically zoned for Cr, Ca, Ti and water contents. Garnets contain 0 to 20 ppm H2 Despite the fast diffusion rate of H in mantle m inerals, the observations above indicate that the water contents of mantle xenolith minerals were not disturbed during kimberlite entrainment and that the measured water data represent mantle values. Trace elements in all minerals show various degrees of light REE and LILE enrichments indicative of minimal to strong metasomatism. Water contents of peridotite minerals from the Kaapvaal lithosphere are not related to the degree of depletion of the peridotites. Instead, metasomatism exerts a clear control on the amount of water of mantle minerals. Xenoliths from each location record specific types of metasomatism with different outcomes for the water contents of mantle minerals. At pressures . 5.5 GPa, highly alkaline melts metasomatized Liqhobong and Kimberley peridotites, and increased the water contents of their olivine, pyroxenes and garnet. At higher pressures, the circulation of ultramafic melts reacting with peridotite resulted in co-variation of Ca, Ti and water at the edge of garnets at Jagersfontein, overall decreasing their water content, and lowered the water content of olivines at Finsch Mine. The calculated water content of these melts varies depending on whether the water content of the peridotite (2 wt% HO. 2O) or individual m inerals (<0.5-13 wt% H2O) are used, and also depend on the mineral-melt water partition coefficients. These metasomatic events are thought to have occurred during the Archean and Proterozoic, meaning that the water contents measured here have been preserved since that time and can be used to investigate viscocity and longevity of cratonic mantle roots.

  9. Raman spectroscopic study of metamorphic diamonds in garnet-clinopyroxene rock from the Kokchetav Massif

    NASA Astrophysics Data System (ADS)

    Takabe, S.; Ogasawara, Y.; Schertl, H. P.

    2014-12-01

    Diamond-bearing garnet-clinopyroxene rock (sample nos. 24997 and 25018) contains large-grained "microdiamonds" (ca. 150 µm at average) which are described as 2 types, cuboids and "ball-shaped" morphologies. Recently, we found another type of 2 grains; small-grained type (ca. 10 µm, rounded-shaped with smooth surface), completely included in garnet in the same rock with large-grained diamond. The Raman and photoluminescence (PL) spectroscopy were conducted in order to characterize diamond in garnet-clinopyroxene rock among the various diamonds in the Kokchetav UHPM rocks. 12 cuboids and 2 small-grained diamonds were analyzed by Raman spectroscopy using Ar+ laser (514.5 nm). The positions with the full widths at half maximum (FWHM) of Raman band of diamond are (cuboids): 1331.1-1332.1 cm-1 with 4.23-5.34 cm-1, and (small-grained): 1334.0-1334.7 cm-1 with 4.75-4.79 cm-1. The higher peak positions of small-grained type compared to cuboids were caused by internal (residual) pressure from the host garnet. 2D Raman mappings at different focal depths were also conducted to examine inside the diamond grains. At this moment, no specific variation and no inclusion have been detected in the diamond grains. PL spectra of 2 cuboids and 2 small-grained diamonds were measured using excitation lines of the Ar+ laser and the He-Ne laser (632.8 nm) to confirm PL band. All examined diamonds have a PL band at ca. 639 nm (NV- center) throughout grains. Using Ar+ laser, these 4 diamond grains (both cuboid and small-grained) showed strange PL bands at 554.5-557.5 nm (ca. 1450 cm-1), and their intensity distributions were strongly heterogeneous (sporadic within a diamond grain) within 1-3 ?m scale. These PL bands have been already reported in other Kokchetav diamonds in dolomite marble and garnet-biotite gneiss. Although a wide variation of diamond-bearing rocks occur in the Kokchetav Massif and the formation environments of diamonds are quite diverse, in Raman spectra no critical difference was recognized up to now. Our studies just started and need to become broadened also to other diamond-bearings lithologies.

  10. Multicomponent diffusion in garnets I: general theoretical considerations and experimental data for Fe-Mg systems

    NASA Astrophysics Data System (ADS)

    Borinski, Sascha André; Hoppe, Ulrich; Chakraborty, Sumit; Ganguly, Jibamitra; Bhowmik, Santanu Kumar

    2012-10-01

    We have carried out a combined theoretical and experimental study of multicomponent diffusion in garnets to address some unresolved issues and to better constrain the diffusion behavior of Fe and Mg in almandine-pyrope-rich garnets. We have (1) improved the convolution correction of concentration profiles measured using electron microprobes, (2) studied the effect of thermodynamic non-ideality on diffusion and (3) explored the use of a mathematical error minimization routine (the Nelder-Mead downhill simplex method) compared to the visual fitting of concentration profiles used in earlier studies. We conclude that incorporation of thermodynamic non-ideality alters the shapes of calculated profiles, resulting in better fits to measured shapes, but retrieved diffusion coefficients do not differ from those retrieved using ideal models by more than a factor of 1.2 for most natural garnet compositions. Diffusion coefficients retrieved using the two kinds of models differ only significantly for some unusual Mg-Mn-Ca-rich garnets. We found that when one of the diffusion coefficients becomes much faster or slower than the rest, or when the diffusion couple has a composition that is dominated by one component (>75 %), then profile shapes become insensitive to one or more tracer diffusion coefficients. Visual fitting and numerical fitting using the Nelder-Mead algorithm give identical results for idealized profile shapes, but for data with strong analytical noise or asymmetric profile shapes, visual fitting returns values closer to the known inputs. Finally, we have carried out four additional diffusion couple experiments (25-35 kbar, 1,260-1,400 °C) in a piston-cylinder apparatus using natural pyrope- and almandine-rich garnets. We have combined our results with a reanalysis of the profiles from Ganguly et al. (1998) using the tools developed in this work to obtain the following Arrhenius parameters in D = D 0 exp{-[ Q 1bar + ( P-1)? V +]/ RT} for D {Mg/*} and D {Fe/*}: Mg: Q 1bar = 228.3 ± 20.3 kJ/mol, D 0 = 2.72 (±4.52) × 10-10 m2/s, Fe: Q 1bar = 226.9 ± 18.6 kJ/mol, D 0 = 1.64 (±2.54) × 10-10 m2/s. ? V + values were assumed to be the same as those obtained by Chakraborty and Ganguly (1992).

  11. Potential use of gallium-doped phosphate-based glass material for periodontitis treatment.

    PubMed

    Sahdev, Rohan; Ansari, Tahera I; Higham, Susan M; Valappil, Sabeel P

    2015-07-01

    This study aimed at evaluating the potential effect of gallium-incorporated phosphate-based glasses towards periodontitis-associated bacteria, Porphyromonas gingivalis, and matrix metalloproteinase-13. Periodontitis describes a group of inflammatory diseases of the gingiva and supporting structures of the periodontium. They are initiated by the accumulation of plaque bacteria, such as the putative periodontal pathogen Porphyromonas gingivalis, but the host immune response such as elevated matrix metalloproteinases are the major contributing factor for destruction of periodontal tissues. Antibacterial assays of gallium-incorporated phosphate-based glasses were conducted on Porphyromonas gingivalis ATCC 33277 using disc diffusion assay on fastidious anaerobe agar and liquid broth assay in a modified tryptic soy broth. In vitro study investigated the effect of gallium on purified recombinant human matrix metalloproteinase-13 activity using matrix metalloproteinase assay kit. In vivo biocompatibility of gallium-incorporated phosphate-based glass was evaluated in rats as subcutaneous implants. Antibacterial assay of gallium displayed activity against Porphyromonas gingivalis (inhibition zone of 22?±?0.5?mm compared with 0?mm for control glass, c-PBG). Gallium in the glass contributed to growth inhibitory effect on Porphyromonas gingivalis (up to 1.30 reductions in log?10 values of the viable counts compared with control) in a modified tryptic soy broth. In vitro study showed gallium-incorporated phosphate-based glasses inhibited matrix metalloproteinase activity significantly (p???0.01) compared with c-PBG. Evaluation of in vivo biocompatibility of gallium-incorporated phosphate-based glasses in rats showed a non-toxic and foreign body response after 2 weeks of implantation. The results indicate that gallium ions might act on multiple targets of biological mechanisms underlying periodontal disease. Moreover, gallium-incorporated phosphate-based glasses are biocompatible in a rat model. The findings warrant further investigation and will have important clinical implications in the future treatment and management of periodontitis. PMID:25681404

  12. Plasmon resonance enhancement of Faraday rotation of liquid phase epitaxy grown garnet films populated with gold nanoparticles on the film surfaces

    NASA Astrophysics Data System (ADS)

    Lang, G. S.; Bowen, D.; Krafft, C.; Mayergoyz, I. D.

    2014-05-01

    Enhancement of the Faraday rotation of rare-earth iron garnet thin films offers the promise for development of compact and higher performance polarization dependent optical devices. Faraday rotation enhancement has been achieved utilizing strong localized electric fields induced by the excitation of plasmon resonances in gold nanoparticles deposited on garnet films. This paper presents experimental results that reveal strong Faraday rotation enhancement in bismuth-doped garnet films with gold nanoparticles of various dimensions and separations deposited on the epitaxial films. Stronger enhancements can be obtained by increasing the height and relative spacing between the nanoparticles formed on the garnet film surfaces.

  13. Assessment of Renal Artery Stenosis: Comparison of Captopril Renography and Gadolinium-Enhanced Breath-Hold MR Angiography

    Microsoft Academic Search

    V. BONGERS; J. BAKKER; J. J. BEUTLER; F. J. A. BEEK; J. M. H. DE KLERK

    2000-01-01

    AIM: To determine the accuracy of captopril renography (CR) and gadolinium-enhanced breath-hold magnetic resonance (MR) angiography in the diagnosis of 50–99% renal artery stenosis (RAS).MATERIALS AND METHODS: Forty-three patients with possible RAS, of whom 53% had renal function impairment (creatinine >130?mol\\/l), were included.99mTc-mercaptoacetyl triglycine (MAG3) renography was performed after an oral dose of 25mg captopril. Gadolinium-enhanced MR angiography was performed

  14. Comparison of digital subtraction angiography with gadolinium-enhanced magnetic resonance angiography in the diagnosis of renal artery stenosis

    Microsoft Academic Search

    J. Thornton; J. O'Callaghan; J. Walshe; E. O'Brien; J. C. Varghese; M. J. Lee

    1999-01-01

    .   Renal artery stenosis (RAS) is a treatable cause of hypertension and renal failure for which no ideal screening technique\\u000a is currently available. We evaluated the use of dynamic gadolinium-enhanced magnetic resonance angiography (MRA) for the diagnosis\\u000a of RAS. Sixty-two patients with secondary hypertension were enrolled in the study. All patients had conventional renal angiography\\u000a and gadolinium enhanced MRA. The

  15. Garnets in porphyry-skarn systems: A LA-ICP-MS, fluid inclusion, and stable isotope study of garnets from the Hongniu-Hongshan copper deposit, Zhongdian area, NW Yunnan Province, China

    NASA Astrophysics Data System (ADS)

    Peng, Hui-juan; Zhang, Chang-qing; Mao, Jing-wen; Santosh, M.; Zhou, Yun-man; Hou, Lin

    2015-05-01

    The Late Cretaceous Hongniu-Hongshan porphyry-skarn copper deposit is located in the Zhongdian area of northwestern Yunnan Province, China. Garnets from the deposit have compositions that range from Adr14Grs86 to almost pure andradite (Adr98Grs2) and display two different styles of zoning. The garnets are predominantly of magmatic-hydrothermal origin, as is evidenced by their 18Ofluid (5.4-6.9‰) and low Dfluid (-142‰ to -100‰) values, both of which likely result from late-stage magmatic open-system degassing. Three generations of garnet have been identified in this deposit: (1) Al-rich garnets (Grt I; Adr22-57Grs78-43) are anisotropic, have sector dodecahedral twinning, are slightly enriched in light rare earth elements (LREEs) compared with the heavy rare earth elements (HREEs), have negative or negligible Eu anomalies, and contain high concentrations of F. Fluid inclusions within these Al-rich garnets generally have salinities of 12-39 wt.% NaCl eq. and have liquid-vapor homogenization temperatures (Th) of 272-331 °C. The Grt I are most likely associated with low- to medium-salinity fluids that were generated by the contraction of an ascending vapor phase and that formed during diffusive metasomatism caused by pore fluids equilibrating with the host rocks at low W/R (water/rock) ratios. These garnets formed as a result of the high F activity of the system, which increased the solubility of Al within the magmato-hydrothermal fluids in the system. (2) Fe-rich garnets (Adr75-98Grs25-2) have trapezohedral faces, and are both anisotropic with oscillatory zoning and isotropic. These second-generation Fe-rich garnets (Grt II) have high ?REE concentrations, are LREE-enriched and HREE-depleted, and generally have positive but variable Eu anomalies. All of the Fe-rich garnets contain high-salinity fluid inclusions with multiple daughter minerals with salinities of 33-80 wt.% NaCl eq. Some of them show higher temperatures of halite dissolution (465-591 °C) than liquid-vapor homogenization temperatures (319-473 °C), and several Fe-rich garnets contain inclusion groups indicative of boiling. The Grt II are associated with high-temperature, hypersaline fluids that were segregated from magma at a depth of at least 5.6 km and reacted with carbonates at depths shallower than 2.0 km. (3) Al-rich garnet veins (Adr14-60Grs86-40) contain allotriomorphic crystals, have lower HFSE (high field strength element) and REE concentrations than the other garnets, and have HREE-enriched and LREE-depleted patterns with small Eu anomalies that are typical of the majority of garnets. The Grt III most likely formed from residual metasomatic fluids.

  16. Survival of rabbit platelets labeled with gallium 67

    SciTech Connect

    Mazoyer, E.; Carpenter, D.; Ebbe, S.; Yano, Y.; Dalal, K.; Singh, M.; Mazoyer, B.

    1988-02-01

    The viability of rabbit platelets labeled with radioactive gallium was determined to analyze the feasibility of using platelets labeled with gallium 67 as an imaging reagent for positron emission tomography. Platelets were labeled with a complex of the longer lived gallium 67 and mercaptopyridine-N-oxide (MPO) or with sodium chromate Cr 51. Their survival after transfusion was measured. Labelling efficiency of /sup 67/Ga-MPO was 6.5% to 45.8% (26.8% +/- 2.8%) when platelets were suspended in saline solution, but was much lower (1.6% +/- 0.8%) in plasma. Platelets labeled with either radioisotope in a saline medium survived as well as platelets labeled with 51Cr in plasma. Recovery values 1 hour after transfusion and mean platelet survivals were 68.6% +/- 4.9% and 3.4 +/- 0.2 days for /sup 67/Ga in saline solution, 76.5% +/- 6.8% and 3.8 +/- 0.5 days for /sup 51/Cr in saline solution, and 73.7% +/- 7.4% and 3.6 +/- 0.5 days for /sup 51/Cr in plasma. Labeled platelet concentrates always contained extra radioactivity not firmly bound to viable platelets. A postlabeling wash in saline solution did not reduce this contamination and resulted in reduction of the number of viable platelets. The results showed that rabbit platelets labeled with /sup 67/Ga-MPO survived in the circulation as well as those labeled by a standard protocol with sodium chromate Cr 51.

  17. Self-diffusion in liquid gallium and hard sphere model

    NASA Astrophysics Data System (ADS)

    Blagoveshchenskii, Nikolay; Novikov, Arkady; Puchkov, Alexander; Savostin, Vadim; Sobolev, Oleg

    2015-01-01

    Incoherent and coherent components of quasielastic neutron scattering have been studied in the temperature range of T = 313 K - 793 K aiming to explore the applicability limits of the hard-sphere approach for the microscopic dynamics of liquid gallium, which is usually considered as a non-hard-sphere system. It was found that the non-hard-sphere effects come into play at the distances shorter than the average interatomic distance. The longer range diffusive dynamics of liquid Ga is dominated by the repulsive forces between the atoms.

  18. Gallium uptake in tryptophan-related pulmonary disease

    SciTech Connect

    Kim, S.M.; Park, C.H.; Intenzo, C.M.; Patel, R. (Thomas Jefferson Univ. Hospital, Philadelphia, PA (USA))

    1991-02-01

    We describe a patient who developed fever, fatigue, muscle weakness, dyspnea, skin rash, and eosinophilia after taking high doses of tryptophan for insomnia for two years. A gallium-67 scan revealed diffuse increased uptake in the lung and no abnormal uptake in the muscular distribution. Bronchoscopy and biopsy confirmed inflammatory reactions with infiltration by eosinophils, mast cells, and lymphocytes. CT scan showed an interstitial alveolar pattern without fibrosis. EMG demonstrated diffuse myopathy. Muscle biopsy from the right thigh showed an inflammatory myositis with eosinophilic and lymphocytic infiltrations.

  19. Testing of gallium arsenide solar cells on the CRRES vehicle

    NASA Technical Reports Server (NTRS)

    Trumble, T. M.

    1985-01-01

    A flight experiment was designed to determine the optimum design for gallium arsenide (GaAs) solar cell panels in a radiation environment. Elements of the experiment design include, different coverglass material and thicknesses, welded and soldered interconnects, different solar cell efficiencies, different solar cell types, and measurement of annealing properties. This experiment is scheduled to fly on the Combined Release and Radiation Effects Satellite (CRRES). This satellite will simultaneously measure the radiation environment and provide engineering data on solar cell degradation that can be directly related to radiation damage.

  20. Lasing action in gallium nitride quasicrystal nanorod arrays.

    PubMed

    Chang, Shih-Pang; Sou, Kuok-Pan; Chen, Chieh-Han; Cheng, Yuh-Jen; Huang, Ji-Kai; Lin, Chung-Hsiang; Kuo, Hao-Chung; Chang, Chun-Yen; Hsieh, Wen-Feng

    2012-05-21

    We report the observation of lasing action from an optically pumped gallium nitride quasicrystal nanorod arrays. The nanorods were fabricated from a GaN substrate by patterned etching, followed by epitaxial regrowth. The nanorods were arranged in a 12-fold symmetric quasicrystal pattern. The regrowth grew hexagonal crystalline facets and core-shell multiple quantum wells (MQWs) on nanorods. Under optical pumping, multiple lasing peaks resembling random lasing were observed. The lasing was identified to be from the emission of MQWs on the nanorod sidewalls. The resonant spectrum and mode field of the 12-fold symmetric photonic quasicrystal nanorod arrays is discussed. PMID:22714233