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Sample records for scandium gallium garnet

  1. The impact of an erbium, chromium:yttrium-scandium-gallium-garnet laser with radial-firing tips on endodontic treatment.

    Science.gov (United States)

    Schoop, U; Barylyak, A; Goharkhay, K; Beer, F; Wernisch, J; Georgopoulos, A; Sperr, W; Moritz, A

    2009-01-01

    Radial-firing tips should allow a more homogeneous laser irradiation of root canal walls. The aim of the study was to assess the effects of erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser irradiation in conjunction with those newly designed tips. The investigation comprised bacteriology, morphological evaluations and temperature measurements. Root canals were inoculated with two test strains and laser irradiated with power settings of 0.6 W and 0.9 W and a repetition rate of 20 Hz. Subsequently, the samples were subjected to microbiological evaluation. The morphological changes of the canal walls were assessed by scanning electron microscopy. To reveal possible thermal side effects, we carried out temperature measurements. The bacteriological evaluation revealed a decisive disinfectant effect. Scanning electron microscopy showed the homogeneous removal of smear layer from the root canal walls. The temperature rise at the root surface during the irradiation was moderate, yielding 1.3 degrees C for the 0.6 W setting and 1.6 degrees C for the 0.9 W setting. The investigations indicated that the Er,Cr:YSGG laser, in conjunction with radial-firing tips, is a suitable tool for the elimination of bacteria in root canals and for the removal of smear layer.

  2. The use of the erbium, chromium:yttrium-scandium-gallium-garnet laser in endodontic treatment: the results of an in vitro study.

    Science.gov (United States)

    Schoop, Ulrich; Goharkhay, Kawe; Klimscha, Johannes; Zagler, Manuela; Wernisch, Johann; Georgopoulos, Apostolos; Sperr, Wolfgang; Moritz, Andreas

    2007-07-01

    The use of the erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser has become accepted in the field of cavity preparation. The development of miniaturized and flexible fiber tips has allowed this device to be used in endodontics. The authors conducted an in vitro study to assess the effects of Er,Cr:YSGG laser irradiation on root canals. The authors inoculated root canals with two bacteria, laser irradiated them at two power settings and subjected them to a quantitative microbiological evaluation. They used scanning electron microscopy (SEM) to assess morphological changes in endodontically processed and laser-irradiated root canal walls. They measured temperature increases on the root surface to determine possible thermal side effects. The bacteriological evaluation revealed a disinfecting effect in the root dentin samples that was dependent on the output power but not specific for the bacterial species investigated. SEM showed the removal of the smear layer from the root canal walls and the exposure of dentinal tubules. The temperature rise during irradiation was moderate when standardized power settings were used. The Er,Cr:YSGG laser can be used to eliminate bacteria in root canals. It also effectively removes smear layer and debris from the canal wall. Practitioners can use the Er,Cr:YSGG laser to prepare root canals for endodontic therapy.

  3. High-fluence and high-density treatment of perioral rhytides using a new, fractionated 2,790-nm ablative erbium-doped Yttrium Scandium Gallium Garnet Laser.

    Science.gov (United States)

    Ciocon, David H; Hussain, Mussarat; Goldberg, David J

    2011-06-01

    In this study, we evaluated the safety and efficacy of a novel 2,790-nm erbium-doped yttrium scandium gallium garnet (Er:YSGG) laser system for the treatment of facial photodamage and perioral wrinkles using a single-treatment, high-fluence, high-density protocol. Eleven female participants with Fitzpatrick skin types II to III and facial wrinkles underwent a single full-face fractional ablative treatment with a 2,790-nm Er:YSGG laser. Follow-up visits were completed at 1, 2, and 6 weeks 3 and 6 months. Quartile improvement scale (0-4) and Fitzpatrick wrinkle scores (1-9) were used for the assessments. Based on blinded photographic assessments, the mean difference in Fitzpatrick wrinkle scores for full face wrinkles was 1.5 ± 1.2 (a reduction from 6.6 to 5.1; paired t-test, p = .003). There was also a statistically significant mean reduction of 1.7 ± 1.3 in perioral wrinkle scores (from 6.7 to 5.0; p = .002). No serious adverse events were reported. A novel, fractionated, ablative 2,790-nm Er:YSGG laser can safely and effectively treat photodamage and perioral wrinkles in a single treatment using a high-fluence, high-density protocol. Cutera provided the equipment used in this study and funding to Dr. Goldberg. © 2011 by the American Society for Dermatologic Surgery, Inc.

  4. Treatment of infraorbital dark circles in atopic dermatitis with a 2790-nm erbium: yttrium scandium gallium garnet laser: a pilot study.

    Science.gov (United States)

    Park, Kui Young; Oh, In Young; Moon, Nam Ju; Seo, Seong Jun

    2013-04-01

    Although many Asian atopic patients have orbital darkening symptom and the demand to treat this condition is increasing, little has been reported in the literature on the treatment of infraorbital dark circles in atopic dermatitis. To evaluate the clinical efficacy and safety of 2790-nm erbium:yttrium scandium gallium garnet (Er:YSGG) laser therapy for reducing infraorbital dark circles in atopic dermatitis patients. Ten Korean patients over 21 year with mild atopic dermatitis and infraorbital dark circles were enrolled in this study. Patients who need active atopic dermatitis treatments are excluded because of the possibility of aggravation after laser treatment. They were treated for dark circles using a 2790-nm Er:YSGG laser. The treatment parameters were 1.8-2.2 J/cm² fluence, 6-mm spot size, and 0.3-ms pulse width with 10% overlap over the infraorbital areas once with a 4-week interval between treatments. Efficacy was assessed with a quartile grading score ranging from 0 to 5 by a blinded investigator, and the patients also documented their degree of satisfaction with the same grading score. All possible side effects were evaluated. The clinical assessment showed 74.5% (2.7) and 72.5% (2.5) improvements, and the patient satisfaction scale scores improved an average of 74% (2.4) and 71.5% (2.3) at 2 months and 4 months after treatment, respectively. There were no severe side effects or aggravation of atopic dermatitis. Our study suggests that 2790-nm Er:YSGG laser therapy can be effectively and safely used in the treatment of infraorbital dark circles in atopic dermatitis patients.

  5. Effects of erbium‑and chromium‑doped yttrium scandium gallium ...

    African Journals Online (AJOL)

    2014-08-21

    Aug 21, 2014 ... surfaces because of its high power, and the ablation was deeper for these samples. High‑magnification SEM ... Key words: Erbium chromium‑doped yttrium scandium gallium garnet, diode laser, restorative dental materials, scanning electron ... garnet (Nd: YAG) and carbon dioxide (CO2) lasers on indirect ...

  6. Effects of erbium-and chromium-doped yttrium scandium gallium garnet and diode lasers on the surfaces of restorative dental materials: a scanning electron microscope study.

    Science.gov (United States)

    Hatipoglu, M; Barutcigil, C

    2015-01-01

    The aim of this study is to evaluate the potential effects of laser irradiation, which is commonly performed in periodontal surgery, on the surfaces of restorative materials. Five different restorative dental materials were used in this study, as follows: (1) Resin composite, (2) poly acid-modified resin composite (compomer), (3) conventional glass ionomer cement (GIC), (4) resin-modified glass ionomer cement (RMGIC), and (5) amalgam. Four cylindrical samples (8 mm diameter, 2 mm height) were prepared for each restorative material. In addition, four freshly extracted, sound human incisors teeth were selected. Two different laser systems commonly used in periodontal surgery were examined in this study: A 810 nm diode laser at a setting of 1 W with continuous-phase laser irradiation for 10 s, and an erbium-and chromium-doped yttrium scandium gallium garnet (Er, Cr: YSGG) laser at settings of 2.5 W, 3.25 W, and 4 W with 25 Hz laser irradiation for 10 s. Scanning electron microscopy (SEM) analysis was performed to evaluate the morphology and surface deformation of the restorative materials and tooth surfaces. According to the SEM images, the Er, Cr: YSGG laser causes irradiation markings that appear as demineralized surfaces on tooth samples. The Er, Cr: YSGG laser also caused deep defects on composite, compomer, and RMGIC surfaces because of its high power, and the ablation was deeper for these samples. High-magnification SEM images of GIC samples showed the melting and combustion effects of the Er, Cr: YSGG laser, which increased as the laser power was increased. In amalgam samples, neither laser left significant harmful effects at the lowest power setting. The diode laser did cause irradiation markings, but they were insignificant compared with those left by the Er, Cr: YSGG laser on the surfaces of the different materials and teeth. Within the limitations of this study, it can be concluded that Er, Cr: YSGG laser irradiation could cause distortions of the surfaces

  7. The effect of erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser therapy on pain during cavity preparation in paediatric dental patients: a pilot study.

    Science.gov (United States)

    Eren, Figen; Altinok, Basak; Ertugral, Ferhan; Tanboga, Ilknur

    2013-06-01

    Standard treatment for caries removal and cavity preparation for restorations using mechanical means is often accompanied by fear and pain for the patient. Although the pain may be reduced by local anaesthesia, fear of the needle, noise, and the vibration of mechanical preparation remain a cause of discomfort. Erbium, chromium:yttriumscandium- gallium-garnet (Er,Cr:YSGG) laser irradiation indicates that pain perception may be reduced relative to that caused by mechanical preparation. The aim of this pilot clinical study was to perform a preliminary evaluation of pain perception during cavity preparation comparing the mechanical removal and Er,Cr:YSGG laser removal of caries from enamel and dentine. The study sample was ten children aged 7 to 12 years. Half of the preparations were completed by the laser alone and the other half were mechanically prepared. All cavities were restored with light-cured composite resin following the application of acid etch and a bonding agent. The time spent on cavity preparation and the behaviour of the patients during cavity preparation were recorded. Children were instructed to rate their pain on a visual analogue scale. In addition, the patients were asked to decide which was the more uncomfortable form of treatment and the preferred treatment for future caries therapy. Children showed considerably more body and head movement with the conventional mechanical preparation. The subjects rated the perception of pain lower when the laser technique was used. In the small number of children studied, the application of the Er,Cr:YSGG laser system was a more comfortable alternative or adjunctive method to conventional mechanical cavity preparation. A far larger study is necessary to confirm this finding.

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

    Science.gov (United States)

    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.

  9. Czochralski crystal growth and aluminum segregation coefficient in yttrium gallium aluminum garnet

    Science.gov (United States)

    Dabkowski, A.; Berkowski, M.; Jasiołek, G.

    1985-04-01

    The aluminum distribution coefficient and the amount of octahedral yttrium aluminum gallium garnet single crystals obtained by the Czochralski method have been determined from lattice constant variations during crystal growth. The value of the aluminum distribution coefficient was close to 2 for those parts of the crystal with a convex solid-liquid interface and it was close to 1 for those with a flat solid-liquid interface. The large difference between these values can be explained by chemical stresses in the crystal in the meltback region and small changes of the lattice constant in the part of crystal with a flat solid-liquid interface. Single crystals of yttrium aluminum gallium garnet with a lattice constant appropriate for LPE film growth of yttrium gallium garnet have been grown.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Magneto-optical properties of the Ca:(yttrium iron garnet) epitaxial-layer-substrate interface on gadolinium gallium garnet

    Science.gov (United States)

    Gualtieri, D. M.

    1990-05-01

    Calcium oxide is a growth rate inhibitor of the liquid-phase epitaxy (LPE) of garnet layers. Calcium oxide additions to a melt for the growth of yttrium iron garnet (YIG) will reduce the epitaxial growth rate from its typical value of 1.0 to 0.1 μm/min [W. H. De Roode and J. M. Robertson, J. Cryst. Growth 63, 105 (1983)], allowing precise thickness control for the fabrication of optical waveguides and magnetic heterostructures. LPE growth of YIG from calcium-free melts produces a 0.1-0.5 μm interface layer between the YIG layer and the gadolinium gallium garnet (GGG) substrate. This interface is caused by a transient crystal growth that occurs before equilibrium epitaxy, and it consists of a nonstoichiometric layer composition that includes flux and impurity components. Calcium oxide addition would be especially useful if it reduced the thickness of the interface layer in proportion to its inhibition of growth rate. This, however, is not the case. A series of Ca:YIG layers was grown by LPE on GGG substrates in the thickness range 0.05-10 μm. Faraday rotation spectroscopy in the wavelength range 475-575 nm distinguished the layer, interface, and substrate contributions to the optical rotation and revealed the presence of a 0.25-μm-thick interface layer with properties characteristic of Pb-substituted YIG. Double-crystal x-ray diffraction confirmed the existence of the interface by the angular broadening of the layer diffraction and a shifting to lattice constants intermediate between YIG and GGG as the layer thickness decreased. The importance of this interface as a graded refractive index layer in optical waveguides should not be overlooked.

  12. Iron implantation in gadolinium gallium garnet studied by conversion-electron Moessbauer spectroscopy

    CERN Document Server

    Szucs, I; Fetzer, C; Langouche, G

    1998-01-01

    Gadolinium gallium garnet single crystals were implanted with doses of sup 5 sup 7 Fe ions in the range 8x10 sup 1 sup 5 - 6x10 sup 1 sup 6 atoms cm sup - sup 2. Depending on the dose, iron with Fe sup 2 sup + or Fe sup 3 sup + charge states was found to have formed after the implantation. After a subsequent annealing in air, the iron oxidized to Fe sup 3 sup +. The Moessbauer and channelling measurements showed lattice recrystallization taking place at 600 deg. C. After recrystallization, the iron was found to have substituted for gallium ions both at the octahedral and at the tetrahedral positions. The relative concentration of the two types of iron at the two sites shifted towards the equilibrium distribution upon high-temperature annealing. (author)

  13. Electromagnetic properties of terbium gallium garnet at millikelvin temperatures and low photon energy

    Science.gov (United States)

    Kostylev, Nikita; Goryachev, Maxim; Bushev, Pavel; Tobar, Michael E.

    2017-07-01

    Electromagnetic properties of single crystal terbium gallium garnet are characterised from room down to millikelvin temperatures using the whispering gallery mode method. Microwave spectroscopy is performed at low powers equivalent to a few photons in energy and conducted as functions of the magnetic field and temperature. A phase transition is detected close to the temperature of 3.5 K. This is observed for multiple whispering gallery modes causing an abrupt negative frequency shift and a change in transmission due to extra losses in the new phase caused by a change in complex magnetic susceptibility.

  14. Ultralarge magneto-optic rotations and rotary dispersion in terbium gallium garnet single crystal.

    Science.gov (United States)

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

    2015-06-10

    We report systematically acquired data on the Verdet constant of terbium gallium garnet for wavelengths ranging from visible to near-infrared (405-830 nm) regime. Our experimental method of Stokes polarimetry is based on the Fourier decomposition of the received light intensity and allows unambiguous determination of both the Faraday rotation and the ellipticity of the emergent light. Temperature-dependent investigations in the range of 8-300 K extend earlier reports and verify the Verdet's constant direct dependence on the magnetization, whose first-order approximation is simply a manifestation of the Curie's law. Further, a least-squares fitting of the experimental data correlates well with theoretical predictions. At a wavelength of 405 nm and temperature of 8 K, the rotation is approximately 500°.

  15. The effect of gallium substitution on the microstructure and magnetic properties of yttrium iron garnet

    Energy Technology Data Exchange (ETDEWEB)

    Zaini, N. Z. M., E-mail: zahirah24@gmail.com; Ibrahim, N. B., E-mail: baayah@ukm.edu.my [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor. Malaysia (Malaysia)

    2015-09-25

    Y{sub 3}Fe{sub (5-y)}Ga{sub y}O{sub 12} (y = 0, 0.4, 1.4 and 2,4) thin films were prepared by sol-gel method and annealed for 2h in oxygen. The thin film’s characteristic were studied by an X-ray diffraction (XRD), a field emission scanning electron microscope (FESEM) and a vibration sample magnetometer (VSM). The XRD show that all films have the garnet phase structure. The grain size particles measured using FESEM were between 45.08 nm to 51.58 nm, and the thickness were between 42 nm to 90 nm. The magnetic properties measured using VSM showed that result was shown with hysteresis loop. The magnetization saturation decreased from 144.26 to 2.76 emu/cm{sup 3} with the increasing substitution gallium. The substitution for y = 2.4 was shown the saturation magnetization was very low. The coercivity increased 35 to 75 Oe due the the increasing grain size.

  16. [Optical and spectral parameters in Ce3+ -doped gadolinium gallium aluminum garnet glass-ceramics].

    Science.gov (United States)

    Gong, Hua; Zhao, Xin; Yu, Xiao-bo; Setsuhisa, Tanabe; Lin, Hai

    2010-01-01

    The crystalline phases of Ce3+ -doped gadolinium gallium aluminum garnet (GGAG) glass-ceramics were investigated by X-ray diffraction, and the fluorescence spectra were recorded under the pumping of blue light-emitting diode (LED) using an integrating sphere of 10-inch in diameter, which connected to a CCD detector. The spectral power distribution of the glass-ceramics was obtained from the measured spectra first, and then the quantum yield was derived based on the photon distribution. The quantum yield of Ce3+ emission in GGAG glass-ceramics is 29.2%, meanwhile, the color coordinates and the correlated color temperature (CCT) of combined white light were proved to be x = 0.319, y = 0.349 and 6086 K, respectively. Although the quantum yield is a little smaller than the value in Ce3+ -doped YAG glass-ceramics, the CCT of the combined white light is much smaller than that in the latter. The optical behavior of GGAG glass-ceramics provides new vision for developing comfortable LED lighting devices.

  17. Optical properties of pure and Ce{sup 3+} doped gadolinium gallium garnet crystals and epitaxial layers

    Energy Technology Data Exchange (ETDEWEB)

    Syvorotka, I.I. [Scientific Research Company “Carat”, 202 Stryjska Street, Lviv 79031 (Ukraine); Sugak, D. [Scientific Research Company “Carat”, 202 Stryjska Street, Lviv 79031 (Ukraine); Lviv Polytechnic National University, 12, S. Bandera Street, Lviv, 79013 (Ukraine); Wierzbicka, A. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Wittlin, A. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Cardinal Stefan Wyszyński University in Warsaw, ul. Dewajtis 5, 01-815 Warsaw (Poland); Przybylińska, H. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Barzowska, J. [Institute of Experimental Physics, Gdańsk University, ul. Wita Stwosza 57, Gdańsk (Poland); Barcz, A. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Institute of Electron Technology, Al. Lotników 32/46, 02-668 Warsaw (Poland); Berkowski, M.; Domagała, J. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Mahlik, S.; Grinberg, M. [Institute of Experimental Physics, Gdańsk University, ul. Wita Stwosza 57, Gdańsk (Poland); Ma, Chong-Geng [College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); and others

    2015-08-15

    Results of X-ray diffraction and low temperature optical absorption measurements of cerium doped gadolinium gallium garnet single crystals and epitaxial layers are reported. In the region of intra-configurational 4f–4f transitions the spectra of the bulk crystals exhibit the signatures of several different Ce{sup 3+} related centers. Apart from the dominant center, associated with Ce substituting gadolinium, at least three other centers are found, some of them attributed to the so-called antisite locations of rare-earth ions in the garnet host, i.e., in the Ga positions. X-ray diffraction data prove lattice expansion of bulk GGG crystals due to the presence of rare-earth antisites. The concentration of the additional Ce-related centers in epitaxial layers is much lower than in the bulk crystals. However, the Ce-doped layers incorporate a large amount of Pb from flux, which is the most probable source of nonradiative quenching of Ce luminescence, not observed in crystals grown by the Czochralski method. - Highlights: • Ce{sup 3+} multicenters found in Gadolinium Gallium Garnet crystals and epitaxial layers. • High quality epitaxial layers of pure and Ce-doped GGG were grown. • Luminescence quenching of Ce{sup 3+} by Pb ions from flux detected in GGG epitaxial layers. • X-ray diffraction allows measuring the amount of the rare-earth antisites in GGG.

  18. Highly transparent cerium doped gadolinium gallium aluminum garnet ceramic prepared with precursors fabricated by ultrasonic enhanced chemical co-precipitation.

    Science.gov (United States)

    Zhang, Ji-Yun; Luo, Zhao-Hua; Jiang, Hao-Chuan; Jiang, Jun; Chen, Chun-Hua; Zhang, Jing-Xian; Gui, Zhen-Zhen; Xiao, Na

    2017-11-01

    Cerium doped gadolinium gallium aluminum garnet (GGAG:Ce) ceramic precursors have been synthesized with an ultrasonic chemical co-precipitation method (UCC) and for comparison with a traditional chemical co-precipitation method (TCC). The effect of ultra-sonication on the morphology of powders and the transmittance of GGAG:Ce ceramics are studied. The results indicate that the UCC method can effectively improve the homogenization and sinterability of GGAG:Ce powders, which contribute to obtain high transparent GGAG ceramic with the highest transmittance of 81%. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Structure and temperature effects on Nd3+ spectra in polycrystalline mixed scandium aluminum garnets Y3ScxAl5-xO12

    Science.gov (United States)

    Lupei, A.; Lupei, V.; Hau, S.; Gheorghe, C.; Voicu, F.

    2015-09-01

    New spectroscopic data obtained from high resolution low temperature absorption and emission spectra of Nd3+ in mixed scandium aluminum garnets Y3ScxAl5-xO12 - (x = 0-2) translucent ceramics revealed transition dependent composition effects: modification of the shapes (Lorentz at x = 0 and 2, quasi-Gauss at x = 1, x-dependent asymmetric for other x values, with obvious multicenter structure for low x), widths and shifts of the lines. Nd3+ electronic structure dependence on structural changes with composition is analyzed in terms of nephelauxetic effect and maximum splitting of manifolds: Sc3+ co-doping reduces the nephelauxetic effect, and the increase of 4F3/2 splitting from 85 cm-1 (x = 0) to 98 cm-1 (x = 2) denotes the lowering of local symmetry. The multicenter structure and inhomogeneous broadening of Nd3+ lines is attributed to crystal field distributions determined by the random occupancy of the octahedral sites by Sc3+ and Al3+. For low x (0.2) the resolved two satellites S1, S2 that accompany Nd:YAG lines are correlated to anisotropic crystal field perturbations produced by the n.n. Sc3+ by analogy to those determined by Y3+-antisites (excess of Y3+ ions that enter in octahedral sites of the melt-grown YAG crystals). The temperature evolution of the Nd3+ spectral characteristics (line intensity, shift, broadening) in the 10-300 K range is analyzed in terms of thermal population of the Stark levels, of the effect on electron-phonon interaction and on lattice expansion. The relevance of the spectroscopic properties on the laser emission characteristics in these systems is discussed.

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

    Science.gov (United States)

    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.

  1. Magnetization and FMR studies of crystal-ion-sliced narrow linewidth gallium-doped yttrium iron garnet

    Science.gov (United States)

    Rachford, F. J.; Levy, M.; Osgood, R. M.; Kumar, A.; Bakhru, H.

    2000-05-01

    Recent interest in employing single-crystal yttrium iron garnet (YIG) films for miniaturized microwave integrated circuit applications has prompted us to study detaching liquid phase epitaxy (LPE) grown YIG films from their gadolinium gallium garnet (GGG) substrates via crystal ion slicing (CIS). We report studies of magnetization and ferromagnetic resonance (FMR) of narrow linewidth gallium-doped YIG (GaYIG) films in various stages of separation from their oriented GGG substrates. All samples were diced from the same three-inch wafer of Y3Fe4.6Ga0.4O12 with 4πMeff of 1070 G and 9.45 GHz FMR linewidth of 0.4±0.1 Oe. The CIS separation process involved (1) implantation with helium ions, (2) flash annealing to remove surface damage, and (3) chemical etching to detach the YIG at the implantation damaged layer. The starting films were 10.8-μm thick. Separation occurred 7 to 8 μm from the front surface in the YIG. The implantation (5×1016cm-2 dosage, 3.8 MeV bias) increased the uniaxial anisotropy of these films. A small cubic anisotropy (˜5 G 60° in-plane periodicity) persisted in both implanted and unimplanted samples. Upon implantation the FMR linewidth increased from 0.4 to 3±0.5 Oe. The detached samples have linewidths ranging from 1.7 to 2.5 Oe. The temperature dependence of the linewidths is roughly exponential decreasing as the temperature is lowered for the unprocessed sample, increasing with reduced temperature for all processed samples. Post-detachment annealing restores the FMR linewidth to 0.55±0.5 Oe.

  2. Optical and magnetooptical properties of bismuth and gallium substituted iron garnet films

    NARCIS (Netherlands)

    Hansteen, F.; Helseth, L.E.; Johansen, T.H.; Hunderi, O.; Kiriliouk, A.I.; Rasing, T.H.M.

    2004-01-01

    A series of iron garnet films of composition Lu3-xBixFe5-yGayO12 grown on (100) oriented GGG substrates have been studied using variable angle spectroscopic ellipsometry and polar Keff spectroscopy (MOKE). The diagonal and off-diagonal components of the permittivity tensor have been determined in

  3. Lattice energies and polarizabilities of lanthanide gallium garnets (Ln{sub 3}Ga{sub 5}O{sub 12})

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Dimitar, E-mail: petrov_d_n@abv.bg [Department of Physical Chemistry, University of Plovdiv “Paisii Hilendarski”, 24, Tsar Asen Str., 4000 Plovdiv (Bulgaria)

    2013-04-10

    Highlights: ► The lattice energies Δ{sub L}H{sup θ} of Ln{sub 3}Ga{sub 5}O{sub 12} are determined by the Born–Haber cycle. ► The Born–Haber cycle yields the lowest values among three applied methods. ► Molar polarizations P{sub m} of Ln{sub 3}Ga{sub 5}O{sub 12} have been calculated by the Debye equation. ► The derivative (∂Δ{sub L}H{sup θ}/∂P{sub m}) corresponds to the shear moduli of these crystals. - Abstract: Lattice energies Δ{sub L}H{sup θ} of lanthanide gallium garnets Ln{sub 3}Ga{sub 5}O{sub 12} (Ln = Nd–Lu) have been determined from the Born–Haber thermochemical cycle and compared with those previously obtained by atomistic simulations in the Born model or calculated by an empirical equation. The Born–Haber cycle yields the lowest values among the three methods. Molar polarizations P{sub m} of Ln{sub 3}Ga{sub 5}O{sub 12} have been calculated by the Debye equation. It has been found that the partial derivative (∂Δ{sub L}H{sup θ}/∂P{sub m}) corresponds by magnitude to the shear moduli of these crystals.

  4. Gallium

    Science.gov (United States)

    Foley, Nora K.; Jaskula, Brian W.; Kimball, Bryn E.; Schulte, Ruth F.; Schulz, Klaus J.; DeYoung, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Gallium is a soft, silvery metallic element with an atomic number of 31 and the chemical symbol Ga. Gallium is used in a wide variety of products that have microelectronic components containing either gallium arsenide (GaAs) or gallium nitride (GaN). GaAs is able to change electricity directly into laser light and is used in the manufacture of optoelectronic devices (laser diodes, light-emitting diodes [LEDs], photo detectors, and solar cells), which are important for aerospace and telecommunications applications and industrial and medical equipment. GaAs is also used in the production of highly specialized integrated circuits, semiconductors, and transistors; these are necessary for defense applications and high-performance computers. For example, cell phones with advanced personal computer-like functionality (smartphones) use GaAs-rich semiconductor components. GaN is used principally in the manufacture of LEDs and laser diodes, power electronics, and radio-frequency electronics. Because GaN power transistors operate at higher voltages and with a higher power density than GaAs devices, the uses for advanced GaN-based products are expected to increase in the future. Gallium technologies also have large power-handling capabilities and are used for cable television transmission, commercial wireless infrastructure, power electronics, and satellites. Gallium is also used for such familiar applications as screen backlighting for computer notebooks, flat-screen televisions, and desktop computer monitors.Gallium is dispersed in small amounts in many minerals and rocks where it substitutes for elements of similar size and charge, such as aluminum and zinc. For example, gallium is found in small amounts (about 50 parts per million) in such aluminum-bearing minerals as diaspore-boehmite and gibbsite, which form bauxite deposits, and in the zinc-sulfide mineral sphalerite, which is found in many mineral deposits. At the present time, gallium metal is derived mainly as a

  5. Relieving the frustration through M n3 + substitution in holmium gallium garnet

    Science.gov (United States)

    Mukherjee, Paromita; Glass, Hugh F. J.; Suard, Emmanuelle; Dutton, Siân E.

    2017-10-01

    We present a Rapid Communication on the impact of M n3 + substitution in the geometrically frustrated Ising garnet H o3G a5O12 using bulk magnetic measurements and low-temperature powder neutron diffraction. We find that the transition temperature TN=5.8 K for H o3MnG a4O12 is raised by a factor of almost 20 when compared to H o3G a5O12 . Powder neutron diffraction on H o3M nxG a5 -xO12 (x =0.5 ,1 ) below TN shows the formation of a long-range-ordered state with k =(0 ,0 ,0 ) . H o3 + spins are aligned antiferromagnetically along the six crystallographic axes with no resultant moment, whereas the M n3 + spins are oriented along the body diagonals such that there is a net moment along [111]. The magnetic structure can be visualized as ten-membered rings of corner-sharing triangles of H o3 + spins with the M n3 + spins ferromagnetically coupled to each individual H o3 + spin in the triangle. Substitution of M n3 + completely relieves the magnetic frustration with f =θCW/TN˜1.1 for H o3MnG a4O12 .

  6. LPE growth of yttrium lutetium, indium gallium garnet films for optical waveguide formation on a GGG substrate

    Science.gov (United States)

    Kubota, Eishi; Shimokozono, Makoto; Katoh, Yujiro

    1998-07-01

    Yttrium-lutetium, indium-gallium garnet single-crystal films with a composition of { YxLu3-x}[ Yy1Luy2Iny3Ga2-y1-y2-y3]( Ga3) O12 (0⩽x⩽3, y1=0.02x, y2=0.12-0.04x, y3=1.08-0.11x) were grown on - oriented GGG substrate by the LPE technique in order to fabricate a planar optical waveguide. The LPE growth results and optical properties of the films are reported. It was easy to control the composition of the film, because the distribution coefficients of the solutes showed gradual changes with the composition, and the coefficients ratios of Y/Lu and In/Ga, respectively, were 1.33-1.39 and 0.61-1.07. The films had high transparency in the visible and near-infrared regions. In this system, the addition of In increased and refractive index as a result of substitution on the Ga atom site. The films had a refractive index variation of ˜0.7% with the variation in the film composition, and this is large enough for optical waveguide fabrication. To evaluate its optical propagation loss as a waveguide material, a slab waveguide, composed of core and cladding layers, was formed on a GGG substrate. The propagation loss was 1.2 dB/cm at 1523 nm, indicating that the light was confined effectively in the waveguide with a low loss.

  7. Comparative evaluation of surface topography of tooth prepared using erbium, chromium: Yttrium, scandium, gallium, garnet laser and bur and its clinical implications

    Directory of Open Access Journals (Sweden)

    Mahesh Verma

    2015-01-01

    Conclusions: Er, Cr: YSGG laser can be used for preparing tooth and bond strength value achieved by laser preparation alone without surface treatment procedure lies in the range of clinical acceptability.

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

    Energy Technology Data Exchange (ETDEWEB)

    Asada, H., E-mail: asada@yamaguchi-u.ac.jp; Kuwahara, A.; Sakata, N.; Ono, T.; Kishimoto, K.; Koyanagi, T. [Department of Electronic Devices Engineering, Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611 (Japan); Ishibashi, T.; Meguro, A.; Hashinaka, T. [Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188 (Japan)

    2015-05-07

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

  9. Current German Laser and Quantum Optics Research Reviewed at the 50th Annual Meeting of the Physikalische Gesellschaft.

    Science.gov (United States)

    1986-04-23

    has a substantial crys- tingen) described studies with Cr- plus tal growing capability. One paper from Nd-doped gadolinium -scandium- gallium the Hamburg...institute, read by J. Drube, garnets (GSGG), and also with Cr-doped reported on Xe-flashlamp-pumped Cr:CSA(; % gadolinium -scandium- aluminum garnets...ele- scandium- aluminum garnets (YSA) :mdi..’ ments. yttrium-scandium- gallium garnets (YSC). The crystals used in the Spindler & Optical pumping (with a

  10. Industrial garnet

    Science.gov (United States)

    Olson, D.W.

    2000-01-01

    The state of the global industrial garnet industry in 1999 is discussed. Industrial garnet mined in the U.S., which accounts for approximately one-third of the world's total, is usually a solid-solution of almandine and pyrope. The U.S. is the largest consumer of industrial garnet, using an estimated 47,800 st in 1999 as an abrasive and as a filtration medium in the petroleum industry, filtration plants, aircraft and motor vehicle manufacture, shipbuilding, wood furniture finishing operations, electronic component manufacture, ceramics manufacture, and glass production. Prices for crude concentrates ranged from approximately $50 to $110/st and refined garnet from $50 to $215/st in 1999, depending on type, source, quantity purchased, quality, and application.

  11. Phenoxyl radical complexes of gallium, scandium, iron and manganese.

    Science.gov (United States)

    Adam, B; Bill, E; Bothe, E; Goerdt, B; Haselhorst, G; Hildenbrand, K; Sokolowski, A; Steenken, S; Weyhermüller, T; Wieghardt, K

    1997-02-01

    The hexadentate macrocyclic ligands 1,4,7-tris(3,5-dimethyl-2-hydroxybenzyl)-1,4,7-triazacyclononane (L CH 3H3 ), 1,4,7-tris(3,5-di-tert-butyl-2-hydroxybenzyl)-1,4,7-triazacyclononane (L(Bu) H3 ) and 1,4,7-tris(3-tert-butyl-5-methoxy-2-hydroxybenzyl)-1,4,7-triazacyclononane (L OCH 3-H3 ) form very stable octahedral neutral complexes LM(III) with trivalent (or tetravalent) metal ions (Ga(III) , Sc(III) , Fe(III) , Mn(III) , Mn(IV) ). The following complexes have been synthesized: [L(Bu) M], where M = Ga (1), Sc (2), Fe (3); [L(Bu) Mn(IV) ]PF6 (4'); [L OCH 3M], where M = Ga (1 a), Sc (2 a), Fe (3 a); [L OCH 3Mn(IV) ]PF6 (4 a'); [L CH 3M], where M = Sc (2 b), Fe (3 b), Mn(III) (4 b); [L CH 3Mn(IV) ]2 (ClO4 )3 (H3 O)(H2 O)3 (4 b'). An electrochemical study has shown that complexes 1, 2, 3, 1 a, 2 a and 3 a each display three reversible, ligand-centred, one-electron oxidation steps. The salts [L OCH 3Fe(III) ]ClO4 and [L OCH 3Ga(III) ]ClO4 , have been isolated as stable crystalline materials. Electronic and EPR spectra prove that these oxidations produce species containing one, two or three coordinated phenoxyl radicals. The Mössbauer spectra of 3 a and [3 a](+) show conclusively that both compounds contain high-spin iron(III) central ions. Temperature-dependent magnetic susceptibility measurements reveal that 3 a has an S = 5/2 and [3a](+) an S = 2 ground state. The latter is attained through intramolecular antiferromagnetic exchange coupling between a high-spin iron(III) (S1 = 5/2) and a phenoxyl radical (S2 = 1/2) (H = - 2JS1 S2 ; J = - 80 cm(-1) ). The manganese complexes undergo metal- and ligand-centred redox processes, which were elucidated by spectroelectrochemistry; a phenoxyl radical Mn(IV) complex [Mn(IV) L OCH 3](2+) is accessible. Copyright © 1997 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Temperature dependence of the 1.06-microm stimulated emission cross section of neodymium in YAG and in GSGG.

    Science.gov (United States)

    Rapaport, Alexandra; Zhao, Shengzhi; Xiao, Guohua; Howard, Andrew; Bass, Michael

    2002-11-20

    A linear temperature dependence between -70 degrees C and +70 degrees C is reported for the peak stimulated emission cross section of Nd3+ ions in both yttrium aluminum garnet (YAG) and gadolinium scandium gallium garnet (GSGG).

  13. Scandium recovery from slags after oxidized nickel ore processing

    Science.gov (United States)

    Smyshlyaev, Denis; Botalov, Maxim; Bunkov, Grigory; Rychkov, Vladimir; Kirillov, Evgeny; Kirillov, Sergey; Semenishchev, Vladimir

    2017-09-01

    One of the possible sources of scandium production - waste (slags) from processing of oxidized nickel ores, has been considered in present research work. The hydrometallurgical method has been selected as the primary for scandium extraction. Different reagents for leaching of scandium, such as sulfuric acid, various carbonate salts and fluorides, have been tested. Sulfuric acid has been recognized as an optimal leaching reagent. Sulfuric acid concentration of 100 g L-1 allowed recovering up to 97 % of scandium.

  14. Characteristics of epitaxial garnets grown by CVD using single metal alloy sources. [Chemical Vapor Deposition

    Science.gov (United States)

    Besser, P. J.; Hamilton, T. N.; Mee, J. E.; Stermer, R. L.

    1974-01-01

    Single metal alloys have been explored as the cation source in the chemical vapor deposition (CVD) of iron garnets. Growth of good quality single crystal garnet films containing as many as five different cations has been achieved over a wide range of deposition conditions. The relationship of film composition to alloy compositions and deposition conditions has been determined for several materials. By proper choice of the alloy composition and the deposition conditions, uncrazed deposits were grown on (111) gadolinium gallium garnet (GGG) substrates. Data on physical, magnetic and optical properties of representative films is presented and discussed.

  15. Synthesis of ferromagnetic Bi-substituted yttrium iron garnet films by laser ablation

    OpenAIRE

    Kidoh, Hideo; Morimoto, Akiharu; Shimizu, Tastuo

    1991-01-01

    Bismuth‐substituted yttrium iron garnet (Bi:YIG) films were deposited on gadolinium gallium garnet substrate by laser ablation using the ArF excimer laser. This is the first report on the preparation of Bi‐substituted YIG films by laser ablation. Films have a garnet single phase above the substrate temperature of 490 °C, and the film composition does not deviate largely from the target composition and it is almost constant in the temperature range between 490 and 580 °C. The saturation magnet...

  16. Perovskites and garnets

    Energy Technology Data Exchange (ETDEWEB)

    Khattak, C.P.; Wang, F.F.Y.

    1976-01-01

    The preparation and properties of perovskites and garnets are reviewed. Data and information are presented on crystal chemistry, crystal structure, phase equilibria, electrical properties, optical properties, and mechanical properties. (JRD)

  17. Hydroxyl in garnets from Garnet Ridge, northern Arizona

    Science.gov (United States)

    Ogasawara, Y.; Sakamaki, K.; Koga, I.

    2012-12-01

    Various kinds of garnets and garnet-bearing rocks occur in Garnet Ridge, northern Arizona. These garnets have diverse origins such as mantle peridotite, subducted oceanic slab and crustal level metasomatic products (Koga & Ogasawara, 2012, AGU Fall Meeting Abstract). A typical garnet from Garnet Ridge, called "Navajo Ruby" is Cr-bearing pyrope-rich garnet that could be of the mantle peridotite origin, and another interesting garnet occurs in eclogite xenoliths of subducted slab origin, probably of Farallon plate origin (Usui et al., 2003). To understand the water behavior underneath the Colorado Plateau, we measured micro FT-IR spectra for several kinds of garnets from Garnet Ridge. The samples for micro FT-IR analyses are thick sections (50 - 500 micrometer in thickness). The size of analyzed areas is 50 x 50 μm square. We detected significant amounts of OH in "Navajo Ruby" garnets and in other types of garnets; however, OH in the garnet in eclogite xenolith was negligible or below detection limit. The peridotitic garnets (up to 2 cm across) look purplish to red brownish and are rich in pyrope component (up to 78 mol%) with significant amounts of Cr2O3 (up to 5.9 wt%) without chemical zonation. The inclusions of olivine, clinopyroxene, orthopyroxene and apatite were confirmed by laser Raman spectroscopy. The representative FT-IR absorption spectra of this type garnet are: 1) grain A (Pyp52 Alm29 Sps1 Grs14 And2 Uv2) shows two very strong IR absorption bands by OH centered at 3575 and 3660 cm-1, 2) grain B (Pyp63 Alm14 Sps0 Grs12 And1 Uv10) shows a very strong IR absorption at 3575 cm-1, and 3) grain C (Pyp62 Alm20 Sps1 Grs12 And0 Uv5) did not show IR absorption by OH. No heterogeneity of IR absorption by OH was detected in a single grain. The garnets in eclogite xenolith show clear prograde chemical zonation; core (Pyp6 Alm54 Sps1 Grs34 And5 Uv0) to rim (Pyp21 Alm64 Sps2 Grs15 And1 Uv0). The well developed rim of this garnet has no IR absorption band by OH

  18. Is Garnet Stronger Than Olivine?

    Science.gov (United States)

    Katayama, I.; Karato, S.

    2005-12-01

    Garnet and olivine are two important minerals in two geochemically distinct rock types, peridotite and eclogite. Consequently, the relative strength between garnet and olivine is a key factor in understanding the geodynamic behavior of two distinct geochemical "reservoirs". Here we investigated rheology of garnet by shear deformation experiments using the Griggs-type solid medium apparatus. Garnet and olivine samples, whose compositions are Alm46Prp52Grs2 and Fo90 respectively, were together sandwiched between alumina pistons in simple shear geometry. Because of uncertainty in reading differential stress from an external load-cell, we used dislocation density of deformed olivine crystals to infer stress level during deformation. Oxygen fugacity was buffered by the Ni/NiO reaction, and the water content was relatively low (mechanism according to the stress exponent of ~3 based on the stress and strain-rate relation and dynamic recrystallization in deformed garnet. The difference in strain between the garnet and olivine samples is small when the samples are deformed at a higher strain-rate. This may be due to significant contribution of Peierls mechanism in olivine at higher stress because of lower Peierls stress for olivine (9GPa) than garnet (~16GPa). Although our experiments indicated that garnet is weaker than olivine, the creep strength of garnet is likely depending on its chemical composition. If we calculate strength of pyrope based on homogenous temperature normalization (Karato et al. 1995), pyrope is more resistant than olivine. This is consistent with the well-known observation that Mg-rich garnet in mantle peridotite is usually less deformed than olivine. In contrast, garnet in subducted oceanic crust contains higher Fe content, suggesting that garnet-rich layer is weaker than the surrounding peridotitic upper mantle. Our results provide new insights into the geodynamic behavior of garnet-rich regions including the processes of separation of a garnetite

  19. Segregation in garnet LPE

    Science.gov (United States)

    Klages, C.-P.; Tolksdorf, W.

    1986-12-01

    Growth reactions of liquid phase epitaxial iron garnet mixed crystal films can be classified thermodynamically according to the changes of chemical potentials of its components. By using a special experimental procedure, the interpretation of the growth parameter dependence of chemical composition of the LPE layers is considerably facilitated. Interfacial concentrations of rare earth ions, for example, can be evaluated using a minimum of a priori assumptions about the growth mechanism. The analysis of experimental results shows an increase of the chemical potential of the Pb, Bi, and La component in substituted yttrium iron garnet during crystallization (trapping), while for Pr in YIG the chemical potential is constant. The Bi incorporation was found to be not significantly dependent on the crystallographic orientation of the layer ((100), (110) and (111)), if the comparison was done for identical driving force at the interface.

  20. Influence of scandium concentration on power generation figure of merit of scandium aluminum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Akiyama, Morito; Nagase, Toshimi [Measurement Solution Research Center, National Institute of Advanced Industrials Science and Technology, Tosu, Saga 841-0052 (Japan); Umeda, Keiichi; Honda, Atsushi [Murata Manufacturing Co., Ltd., Nagaokakyo, Kyoto 617-8555 (Japan)

    2013-01-14

    The authors have investigated the influence of scandium concentration on the power generation figure of merit (FOM) of scandium aluminum nitride (Sc{sub x}Al{sub 1-x}N) films prepared by cosputtering. The power generation FOM strongly depends on the scandium concentration. The FOM of Sc{sub 0.41}Al{sub 0.59}N film was 67 GPa, indicating that the FOM is five times larger than that of AlN. The FOM of Sc{sub 0.41}Al{sub 0.59}N film is higher than those of lead zirconate titanate and Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} films, which is the highest reported for any piezoelectric thin films. The high FOM of Sc{sub 0.41}Al{sub 0.59}N film is due to the high d{sub 31} and the low relative permittivity.

  1. Lifetime measurements and oscillator strengths in singly ionized scandium and the solar abundance of scandium

    Science.gov (United States)

    Pehlivan Rhodin, A.; Belmonte, M. T.; Engström, L.; Lundberg, H.; Nilsson, H.; Hartman, H.; Pickering, J. C.; Clear, C.; Quinet, P.; Fivet, V.; Palmeri, P.

    2017-12-01

    The lifetimes of 17 even-parity levels (3d5s, 3d4d, 3d6s and 4p2) in the region 57 743-77 837 cm-1 of singly ionized scandium (Sc II) were measured by two-step time-resolved laser induced fluorescence spectroscopy. Oscillator strengths of 57 lines from these highly excited upper levels were derived using a hollow cathode discharge lamp and a Fourier transform spectrometer. In addition, Hartree-Fock calculations where both the main relativistic and core-polarization effects were taken into account were carried out for both low- and high-excitation levels. There is a good agreement for most of the lines between our calculated branching fractions and the measurements of Lawler & Dakin in the region 9000-45 000 cm-1 for low excitation levels and with our measurements for high excitation levels in the region 23 500-63 100 cm-1. This, in turn, allowed us to combine the calculated branching fractions with the available experimental lifetimes to determine semi-empirical oscillator strengths for a set of 380 E1 transitions in Sc II. These oscillator strengths include the weak lines that were used previously to derive the solar abundance of scandium. The solar abundance of scandium is now estimated to logε⊙ = 3.04 ± 0.13 using these semi-empirical oscillator strengths to shift the values determined by Scott et al. The new estimated abundance value is in agreement with the meteoritic value (logεmet = 3.05 ± 0.02) of Lodders, Palme & Gail.

  2. Gallium nitride optoelectronic devices

    Science.gov (United States)

    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.

  3. Investigations in gallium removal

    Energy Technology Data Exchange (ETDEWEB)

    Philip, C.V.; Pitt, W.W. [Texas A and M Univ., College Station, TX (United States); Beard, C.A. [Amarillo National Resource Center for Plutonium, TX (United States)

    1997-11-01

    Gallium present in weapons plutonium must be removed before it can be used for the production of mixed-oxide (MOX) nuclear reactor fuel. The main goal of the preliminary studies conducted at Texas A and M University was to assist in the development of a thermal process to remove gallium from a gallium oxide/plutonium oxide matrix. This effort is being conducted in close consultation with the Los Alamos National Laboratory (LANL) personnel involved in the development of this process for the US Department of Energy (DOE). Simple experiments were performed on gallium oxide, and cerium-oxide/gallium-oxide mixtures, heated to temperatures ranging from 700--900 C in a reducing environment, and a method for collecting the gallium vapors under these conditions was demonstrated.

  4. High energy resolution with transparent ceramic garnet scintillators

    Science.gov (United States)

    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) 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.

  5. Magnetic anisotropies in ultrathin bismuth iron garnet films

    Energy Technology Data Exchange (ETDEWEB)

    Popova, Elena, E-mail: popova@physique.uvsq.fr [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Franco Galeano, Andres Felipe [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Deb, Marwan [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Warot-Fonrose, Bénédicte [Centre d' Elaboration de Matériaux et d' Etudes Structurales (CEMES), CNRS, 29 rue Jeanne Marvig, 31055 Toulouse (France); Transpyrenean Associated Laboratory for Electron Microscopy (TALEM), CEMES-INA, CNRS–Universidad de Zaragoza (Spain); Kachkachi, Hamid [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Gendron, François [Institut des NanoSciences de Paris (INSP), CNRS/Université Pierre et Marie Curie-Paris 6, 4 place Jussieu, Boîte courrier 840, 75252 Paris Cedex 05 (France); Ott, Frédéric [Laboratoire Léon Brillouin (LLB), CNRS/CEA, Bâtiment 563, CEA Saclay, 91191 Gif sur Yvette Cedex (France); and others

    2013-06-15

    Ultrathin bismuth iron garnet Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi{sub 3}Fe{sub 5}O{sub 12} films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi{sub 3}Fe{sub 5}O{sub 12} were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed.

  6. Smelting of Scandium by Microwave Irradiation.

    Science.gov (United States)

    Fujii, Satoshi; Tsubaki, Shuntaro; Inazu, Naomi; Suzuki, Eiichi; Wada, Yuji

    2017-09-27

    Scandium is being explored as an alloying element for aluminum alloys, which are gaining importance as high-performance lightweight structural alloys in the transportation industry. A few years ago, Sc was also found to be suitable for use in electrical devices. High-Sc-content ScAlN thin films have attracted significant attention because of their strong piezoelectricity. The piezoelectric response of ScAlN suggests that ScAlN thin films formed on a hard substrate would be suitable surface acoustic wave wideband filters for next-generation wireless communication systems. However, it is often difficult to use ScAlN thin films in MEMS devices-including acoustic ones-because of the extremely high price of metallic Sc, given the difficulty associated with smelting it. Here, we propose a novel process for smelting Sc metal by microwave irradiation. Sc metal was able to be obtained successfully from ScF₃ through a microwave-irradiation-based carbon reduction reaction. The reaction temperature for this reduction process was approximately 880°C, which is half of that for the conventional smelting process involving reduction with Ca. Thus, the proposed microwave irradiation process has significant potential for use in the smelting of Sc metal.

  7. Smelting of Scandium by Microwave Irradiation

    Directory of Open Access Journals (Sweden)

    Satoshi Fujii

    2017-09-01

    Full Text Available Scandium is being explored as an alloying element for aluminum alloys, which are gaining importance as high-performance lightweight structural alloys in the transportation industry. A few years ago, Sc was also found to be suitable for use in electrical devices. High-Sc-content ScAlN thin films have attracted significant attention because of their strong piezoelectricity. The piezoelectric response of ScAlN suggests that ScAlN thin films formed on a hard substrate would be suitable surface acoustic wave wideband filters for next-generation wireless communication systems. However, it is often difficult to use ScAlN thin films in MEMS devices—including acoustic ones—because of the extremely high price of metallic Sc, given the difficulty associated with smelting it. Here, we propose a novel process for smelting Sc metal by microwave irradiation. Sc metal was able to be obtained successfully from ScF3 through a microwave-irradiation-based carbon reduction reaction. The reaction temperature for this reduction process was approximately 880°C, which is half of that for the conventional smelting process involving reduction with Ca. Thus, the proposed microwave irradiation process has significant potential for use in the smelting of Sc metal.

  8. Hydrometallurgical methods of recovery of scandium from the wastes of various technologies

    Science.gov (United States)

    Molchanova, T. V.; Akimova, I. D.; Smirnov, K. M.; Krylova, O. K.; Zharova, E. V.

    2017-03-01

    The recovery of scandium from the wastes of the production of uranium, titanium, iron-vanadium, and alumina is studied. The applied acid schemes of scandium transfer to a solution followed by ion-exchange recovery and extraction concentration of scandium ensure the precipitation of crude scandium oxides containing up to 5% Sc2O3. Scandium oxides of 99.96-99.99% purity are formed after additional refining of these crude oxides according to an extraction technology using a mixture 15% multiradical phosphine oxide or Cyanex-925 + 15% tributyl phosphate in kerosene.

  9. Synthesis and Reactivity of a Scandium Terminal Hydride: H2  Activation by a Scandium Terminal Imido Complex.

    Science.gov (United States)

    Han, Xianghao; Xiang, Li; Lamsfus, Carlos A; Mao, Weiqing; Lu, Erli; Maron, Laurent; Leng, Xuebing; Chen, Yaofeng

    2017-10-20

    Dihydrogen is easily activated by a scandium terminal imido complex containing the weakly coordinated THF. The reaction proceeds through a 1,2-addition mechanism, which is distinct from the σ-bond metathesis mechanism reported to date for rare-earth metal-mediated H2 activation. This reaction yields a scandium terminal hydride, which is structurally well-characterized, being the first one to date. The reactivity of this hydride is reported with unsaturated substrates, further shedding light on the existence of the terminal hydride complex. Interestingly, the H2 activation can be reversible. DFT investigations further eludciate the mechanistic aspects of the reactivity of the scandium anilido-terminal hydride complex with PhNCS but also on the reversible H2 activation process. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Thermoelectric material comprising scandium doped zinc cadmium oxide

    DEFF Research Database (Denmark)

    2016-01-01

    There is presented a composition of scandium doped Zinc Cadmium Oxide with the general formula ZnzCdxScyO which the inventors have prepared, and for which material the inventors have made the insight that it is particularly advantageous as an n-type oxide material, such as particularly advantageous...

  11. Scandium/carbon filters for soft x rays

    NARCIS (Netherlands)

    Artioukov, IA; Kasyanov, YS; Kopylets, IA; Pershin, YP; Romanova, SA

    2003-01-01

    This Note deals with thin-film soft x-ray filters for operation at the wavelengths near carbon K edge (similar to4.5 nm). The filters were fabricated by magnetron sputtering deposition of thin layers of scandium (total thickness 0.1-0.2 mum) onto films of polypropylene (thickness 1.5 mum) and

  12. Effects of erbium‑and chromium‑doped yttrium scandium gallium ...

    African Journals Online (AJOL)

    Results: According to the SEM images, the Er, Cr: YSGG laser causes irradiation markings that appear as demineralized surfaces on tooth samples. The Er, Cr: YSGG laser also caused deep defects on composite, compomer, and RMGIC surfaces because of its high power, and the ablation was deeper for these samples.

  13. Pure spin current transport in gallium doped zinc oxide

    OpenAIRE

    Althammer, Matthias; Mukherjee, Joynarayan; Geprägs, Stephan; Goennenwein, Sebastian T. B.; Opel, Matthias; Rao, M. S. Ramachandra; Gross, Rudolf

    2016-01-01

    We study the flow of a pure spin current through zinc oxide by measuring the spin Hall magnetoresistance (SMR) in thin film trilayer samples consisting of bismuth-substituted yttrium iron garnet (Bi:YIG), gallium-doped zinc oxide (Ga:ZnO), and platinum. We investigate the dependence of the SMR magnitude on the thickness of the Ga:ZnO interlayer and compare to a Bi:YIG/Pt bilayer. We find that the SMR magnitude is reduced by almost one order of magnitude upon inserting a Ga:ZnO interlayer, and...

  14. Solvent extraction of scandium from lateritic nickel- cobalt ores using different organic reagents

    OpenAIRE

    Ferizoğlu Ece; Kaya Şerif; Topkaya Yavuz A.

    2016-01-01

    Scandium is the most important and strategic metal that can be recovered as a by-product from lateritic nickel-cobalt ores. In this research, different extractants were investigated in order to extract scandium from a sulfate medium by a using a solvent extraction method. Generally, the organic extractants are classified as acidic, neutral and basic organophosphorus compounds. However, in solvent extraction of scandium, the acidic and neutral organophosphorus compounds are preferred due to th...

  15. BASIC RESEARCH ON THE SEPARATION OF SCANDIUM YTTRIUM, AND THE RARE EARTHS BY SOLVENT EXTRACTION.

    Science.gov (United States)

    RARE EARTH ELEMENTS, * SOLVENT EXTRACTION ), (*CHELATE COMPOUNDS, RARE EARTH ELEMENTS), PURIFICATION, ATOMIC SPECTROSCOPY, SCANDIUM, YTTRIUM, PRASEODYMIUM, SAMARIUM, EUROPIUM, GADOLINIUM, TERBIUM, FLUORINE COMPOUNDS, KETONES

  16. Electrodeposition of gallium for photovoltaics

    Science.gov (United States)

    Bhattacharya, Raghu N.

    2016-08-09

    An electroplating solution and method for producing an electroplating solution containing a gallium salt, an ionic compound and a solvent that results in a gallium thin film that can be deposited on a substrate.

  17. Chapter L: U.S. Industrial Garnet

    Science.gov (United States)

    Evans, James G.; Moyle, Phillip R.

    2006-01-01

    The United States presently consumes about 16 percent of global production of industrial garnet for use in abrasive airblasting, abrasive coatings, filtration media, waterjet cutting, and grinding. As of 2005, domestic garnet production has decreased from a high of 74,000 t in 1998, and imports have increased to the extent that as much as 60 percent of the garnet used in the United States in 2003 was imported, mainly from India, China, and Australia; Canada joined the list of suppliers in 2005. The principal type of garnet used is almandite (almandine), because of its specific gravity and hardness; andradite is also extensively used, although it is not as hard or dense as almandite. Most industrial-grade garnet is obtained from gneiss, amphibolite, schist, skarn, and igneous rocks and from alluvium derived from weathering and erosion of these rocks. Garnet mines and occurrences are located in 21 States, but the only presently active (2006) mines are in northern Idaho (garnet placers; one mine), southeastern Montana (garnet placers; one mine), and eastern New York (unweathered bedrock; two mines). In Idaho, garnet is mined from Tertiary and (or) Quaternary sedimentary deposits adjacent to garnetiferous metapelites that are correlated with the Wallace Formation of the Proterozoic Belt Supergroup. In New York, garnet is mined from crystalline rocks of the Adirondack Mountains that are part of the Proterozoic Grenville province, and from the southern Taconic Range that is part of the northern Appalachian Mountains. In Montana, sources of garnet in placers include amphibolite, mica schist, and gneiss of Archean age and younger granite. Two mines that were active in the recent past in southwestern Montana produced garnet from gold dredge tailings and saprolite. In this report, we review the history of garnet mining and production and describe some garnet occurrences in most of the Eastern States along the Appalachian Mountains and in some of the Western States where

  18. Ultra-low damping in lift-off structured yttrium iron garnet thin films

    Science.gov (United States)

    Krysztofik, A.; Coy, L. E.; Kuświk, P.; Załeski, K.; Głowiński, H.; Dubowik, J.

    2017-11-01

    We show that using maskless photolithography and the lift-off technique, patterned yttrium iron garnet thin films possessing ultra-low Gilbert damping can be accomplished. The films of 70 nm thickness were grown on (001)-oriented gadolinium gallium garnet by means of pulsed laser deposition, and they exhibit high crystalline quality, low surface roughness, and the effective magnetization of 127 emu/cm3. The Gilbert damping parameter is as low as 5 ×10-4. The obtained structures have well-defined sharp edges which along with good structural and magnetic film properties pave a path in the fabrication of high-quality magnonic circuits and oxide-based spintronic devices.

  19. Thickness- and temperature-dependent magnetodynamic properties of yttrium iron garnet thin films

    Energy Technology Data Exchange (ETDEWEB)

    Haidar, M., E-mail: mohammad.haidar@Physics.gu.se; Ranjbar, M.; Balinsky, M.; Dumas, R. K. [Department of Physics, University of Gothenburg, 41296 Gothenburg (Sweden); Khartsev, S. [Department of Integrated Devices and Circuits, School of ICT, Royal Institute of Technology (KTH), 16440 Kista (Sweden); Åkerman, J. [Department of Physics, University of Gothenburg, 41296 Gothenburg (Sweden); Materials Physics, School of ICT, Royal Institute of Technology (KTH), 16440 Kista (Sweden)

    2015-05-07

    The magnetodynamical properties of nanometer-thick yttrium iron garnet films are studied using ferromagnetic resonance as a function of temperature. The films were grown on gadolinium gallium garnet substrates by pulsed laser deposition. First, we found that the damping coefficient increases as the temperature increases for different film thicknesses. Second, we found two different dependencies of the damping on film thickness: at room temperature, the damping coefficient increases as the film thickness decreases, while at T = 8 K, we find the damping to depend only weakly on the thickness. We attribute this behavior to an enhancement of the relaxation of the magnetization by impurities or defects at the surfaces.

  20. Gallium-containing anticancer compounds.

    Science.gov (United States)

    Chitambar, Christopher R

    2012-06-01

    There is an ever pressing need to develop new drugs for the treatment of cancer. Gallium nitrate, a group IIIa metal salt, inhibits the proliferation of tumor cells in vitro and in vivo and has shown activity against non-Hodgkin's lymphoma and bladder cancer in clinical trials. Gallium can function as an iron mimetic and perturb iron-dependent proliferation and other iron-related processes in tumor cells. Gallium nitrate lacks crossresistance with conventional chemotherapeutic drugs and is not myelosuppressive; it can be used when other drugs have failed or when the blood count is low. Given the therapeutic potential of gallium, newer generations of gallium compounds are now in various phases of preclinical and clinical development. These compounds hold the promise of greater anti-tumor activity against a broader spectrum of cancers. The development of gallium compounds for cancer treatment and their mechanisms of action will be discussed.

  1. Determination of scandium concentrate composition by WD-XRF and ICP-MS methods

    Science.gov (United States)

    Sarkisova, A. S.; Shibitko, A. O.; Abramov, A. V.; Rebrin, O. I.; Bunkov, G. M.; Lisienko, D. G.

    2017-09-01

    WD-XRF spectroscopy was applied for determining composition of scandium concentrate (ScC) containing 70 % scandium fluoride. Determination of ScC composition was performed using 6 glass beads reference materials produced by fusing synthesized mixture of analyte compounds with the lithium-borate flux in the ratio of 1:10. ScC powder with the known composition was then used as a powder pellet reference material to analyze scandium concentrate from technological line by external standard method. ICP-MS method was employed to control the ScC composition. The statistical data processing and metrological parameters evaluation of the analytical technique developed were carried out.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Gallium--A smart metal

    Science.gov (United States)

    Foley, Nora; Jaskula, Brian W.

    2013-01-01

    Gallium is a soft, silvery metallic element with an atomic number of 31 and the chemical symbol Ga. The French chemist Paul-Emile Lecoq de Boisbaudran discovered gallium in sphalerite (a zinc-sulfide mineral) in 1875 using spectroscopy. He named the element "gallia" after his native land of France (formerly Gaul; in Latin, Gallia). The existence of gallium had been predicted in 1871 by Dmitri Mendeleev, the Russian chemist who published the first periodic table of the elements. Mendeleev noted a gap in his table and named the missing element "eka-aluminum" because he determined that its location was one place away from aluminum in the table. Mendeleev thought that the missing element (gallium) would be very much like aluminum in its chemical properties, and he was right. Solid gallium has a low melting temperature (~29 degrees Celsius, or °C) and an unusually high boiling point (~2,204 °C). Because of these properties, the earliest uses of gallium were in high-temperature thermometers and in designing metal alloys that melt easily. The development of a gallium-based direct band-gap semiconductor in the 1960s led to what is now one of the most well-known applications for gallium-based products--the manufacture of smartphones and data-centric networks.

  4. Tin etching from metallic and oxidized scandium thin films

    Science.gov (United States)

    Pachecka, M.; Lee, C. J.; Sturm, J. M.; Bijkerk, F.

    2017-08-01

    The role of oxide on Sn adhesion to Sc surfaces was studied with in-situ ellipsometry, X-ray photoelectron spectroscopy and secondary electron microscopy. Sn etching with hydrogen radicals was performed on metallic Sc, metallic Sc with a native oxide, and a fully oxidized Sc layer. The results show that Sn adsorbs rather weakly to a non-oxidized Sc surface, and is etched relatively easily by atomic hydrogen. In contrast, the presence of native oxide on Sc allows Sn to adsorb more strongly to the surface, slowing the etching. Furthermore, thinner layers of scandium oxide result in weaker Sn adsorption, indicating that the layer beneath the oxide plays a significant role in determining the adsorption strength. Unexpectedly, for Sn on Sc2O3, and, to a lesser extent, for Sn on Sc, the etch rate shows a variation over time, which is explained by surface restructuring, temperature change, and hydrogen adsorption saturation.

  5. Tin etching from metallic and oxidized scandium thin films

    Directory of Open Access Journals (Sweden)

    M. Pachecka

    2017-08-01

    Full Text Available The role of oxide on Sn adhesion to Sc surfaces was studied with in-situ ellipsometry, X-ray photoelectron spectroscopy and secondary electron microscopy. Sn etching with hydrogen radicals was performed on metallic Sc, metallic Sc with a native oxide, and a fully oxidized Sc layer. The results show that Sn adsorbs rather weakly to a non-oxidized Sc surface, and is etched relatively easily by atomic hydrogen. In contrast, the presence of native oxide on Sc allows Sn to adsorb more strongly to the surface, slowing the etching. Furthermore, thinner layers of scandium oxide result in weaker Sn adsorption, indicating that the layer beneath the oxide plays a significant role in determining the adsorption strength. Unexpectedly, for Sn on Sc2O3, and, to a lesser extent, for Sn on Sc, the etch rate shows a variation over time, which is explained by surface restructuring, temperature change, and hydrogen adsorption saturation.

  6. Extraction of scandium by liquid di-2-ethylhexylphosphoric acid in fusible diluents

    Directory of Open Access Journals (Sweden)

    Ainur Isatayeva

    2015-03-01

    Full Text Available Currently widespread distribution of extraction methods using fusible reagents can be explained by a number of advantages, such as high kinetic characteristics of the process, the ease separation of two phases, high selectivity of many extractants, relatively complete regeneration. For the extraction of scandium in technological order, neutral and cation exchange extractants can be used. Several extraction reagents melt easily at high temperatures, and such melts can be used for extraction. Efficiency of the extraction of metal by cation reagents depends on many factors. Extraction of scandium by melt mixtures of di-2-ethylhexylphosphoric acid - higher carboxylic acid - paraffin and the effect of acidity of the aqueous phase, the concentration of scandium and the aqueous extractant in the organic phase, the volume ratio of organic and aqueous phases on the extraction of metal were studied. It was found that the extraction of scandium proceeds through the cation exchange mechanism. Scandium was extracted quantitatively (> 99.0% from acid solutions. The optimal concentration of di-2-ethylhexylphosphoric acid in the extractant was 0,250 M, quantitative extraction of scandium was observed in the range of its concentrations of 10-3-10-6 M and the volume ratio of organic phases to aqueous phases of 1:5 - 1:20.

  7. Gallium phosphide energy converters

    Science.gov (United States)

    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.

  8. Low-relaxation spin waves in laser-molecular-beam epitaxy grown nanosized yttrium iron garnet films

    Energy Technology Data Exchange (ETDEWEB)

    Lutsev, L. V., E-mail: l-lutsev@mail.ru; Korovin, A. M.; Bursian, V. E.; Gastev, S. V.; Fedorov, V. V.; Suturin, S. M.; Sokolov, N. S. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation)

    2016-05-02

    Synthesis of nanosized yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}, YIG) films followed by the study of ferromagnetic resonance (FMR) and spin wave propagation in these films is reported. The YIG films were grown on gadolinium gallium garnet substrates by laser molecular beam epitaxy. It has been shown that spin waves propagating in YIG deposited at 700 °C have low damping. At the frequency of 3.29 GHz, the spin-wave damping parameter is less than 3.6 × 10{sup −5}. Magnetic inhomogeneities of the YIG films give the main contribution to the FMR linewidth. The contribution of the relaxation processes to the FMR linewidth is as low as 1.2%.

  9. Gallium Safety in the Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Gallium Safety in the Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Thermodynamic and kinetic study of scandium(III) complexes of DTPA and DOTA: a step toward scandium radiopharmaceuticals.

    Science.gov (United States)

    Pniok, Miroslav; Kubíček, Vojtěch; Havlíčková, Jana; Kotek, Jan; Sabatie-Gogová, Andrea; Plutnar, Jan; Huclier-Markai, Sandrine; Hermann, Petr

    2014-06-23

    Diethylenetriamine-N,N,N',N'',N''-pentaacetic acid (DTPA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) scandium(III) complexes were investigated in the solution and solid state. Three (45)Sc NMR spectroscopic references suitable for aqueous solutions were suggested: 0.1 M Sc(ClO4)3 in 1 M aq. HClO4 (δSc =0.0 ppm), 0.1 M ScCl3 in 1 M aq. HCl (δSc =1.75 ppm) and 0.01 M [Sc(ox)4](5-) (ox(2-) = oxalato) in 1 M aq. K2C2O4 (δSc =8.31 ppm). In solution, [Sc(dtpa)](2-) complex (δSc = 83 ppm, Δν = 770 Hz) has a rather symmetric ligand field unlike highly unsymmetrical donor atom arrangement in [Sc(dota)](-) anion (δSc = 100 ppm, Δν = 4300 Hz). The solid-state structure of K8[Sc2(ox)7]⋅13 H2O contains two [Sc(ox)3](3-) units bridged by twice "side-on" coordinated oxalate anion with Sc(3+) ion in a dodecahedral O8 arrangement. Structures of [Sc(dtpa)](2-) and [Sc(dota)](-) in [(Hguanidine)]2[Sc(dtpa)]⋅3 H2O and K[Sc(dota)][H6 dota]Cl2⋅4 H2O, respectively, are analogous to those of trivalent lanthanide complexes with the same ligands. The [Sc(dota)](-) unit exhibits twisted square-antiprismatic arrangement without an axial ligand (TSA' isomer) and [Sc(dota)](-) and (H6 dota)(2+) units are bridged by a K(+) cation. A surprisingly high value of the last DOTA dissociation constant (pKa =12.9) was determined by potentiometry and confirmed by using NMR spectroscopy. Stability constants of scandium(III) complexes (log KScL 27.43 and 30.79 for DTPA and DOTA, respectively) were determined from potentiometric and (45)Sc NMR spectroscopic data. Both complexes are fully formed even below pH 2. Complexation of DOTA with the Sc(3+) ion is much faster than with trivalent lanthanides. Proton-assisted decomplexation of the [Sc(dota)](-) complex (τ1/2 =45 h; 1 M aq. HCl, 25 °C) is much slower than that for [Ln(dota)](-) complexes. Therefore, DOTA and its derivatives seem to be very suitable ligands for scandium

  12. Magnetodielectric coupling in multiferroic holmium iron garnets

    Energy Technology Data Exchange (ETDEWEB)

    Malar Selvi, M.; Chakraborty, Deepannita; Venkateswaran, C., E-mail: cvunom@hotmail.com

    2017-02-01

    Single phase magneto-electric multiferroics require a large magnetic or electric field for producing magneto-electric (ME) and magnetodielectric (MD) effects. For utilizing these effects in devices investigations on the room temperature and low field MD studies are necessary. Recently, efforts have been largely devoted to the investigation of rare earth iron garnets. In the physical method, the preparation of rare earth iron garnet requires high sintering temperature and processing time. To solve these problems, ball milling assisted microwave sintering technique is used to prepare nanocrystalline holmium iron garnets (Ho{sub 3}Fe{sub 5}O{sub 12}). Magnetic and dielectric properties of the prepared sample are investigated. These properties get enhanced in nanocrystalline form when compared to the bulk. The MD coupling of the prepared sample is evident from the anomaly in the temperature dependent dielectric constant plot and the ME coupling susceptibility is derived from the room temperature MD measurements. - Highlights: • Formation of single phase Holmium iron garnet reported. • Ball milling assisted microwave sintering reduces the sintering temperature and time. • Holmium iron garnet shows enhanced magnetic and dielectric properties. • Pyromagnetic and pyroelectric measurements confirm the magnetoelectric coupling. • Room temperature magnetodielectric measurements show the nonlinear behaviour.

  13. Effects of iron on intermetallic compound formation in scandium modified Al–Si–Mg Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Patakham, Ussadawut [National Metal and Materials Technology Center, National Science and Technology Development Agency, 114 Thailand Science Park, Klong Nueng, Klong Luang, Pathumthani 12120 (Thailand); Limmaneevichitr, Chaowalit, E-mail: chaowalit.lim@mail.kmutt.ac.th [Production Engineering Department, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand)

    2014-12-15

    Highlights: • Iron reduces the modification effects of scandium in Al–Si–Mg alloys. • Morphologies of Sc-rich intermetallic phases vary with Fe and Sc contents and the cooling rates. • Sc neutralizes effects of Fe by changing Fe-rich intermetallic phases from platelets to more cubic. - Abstract: In general, iron has a strong tendency to dissolve in molten aluminum. Iron has very low solid solubility in aluminum–silicon casting alloys, so it will form intermetallic compounds that cause detrimental effects on mechanical properties. In this work, the effects of iron on intermetallic compound formations in scandium modified Al–Si–Mg alloys were studied. There were two levels of iron addition (0.2 and 0.4 wt.%) and two levels of scandium addition (0.2 and 0.4 wt.%). We found that the effects of scandium modification decreased with increasing iron addition. The morphologies of the complex intermetallic compounds were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) techniques. It was found that scandium changes the morphology of Fe-rich intermetallic compounds from β-phase (plate-like) to α-phase, which reduces the harmful effects of β-phase.

  14. Solvent extraction of scandium from lateritic nickel- cobalt ores using different organic reagents

    Directory of Open Access Journals (Sweden)

    Ferizoğlu Ece

    2016-01-01

    Full Text Available Scandium is the most important and strategic metal that can be recovered as a by-product from lateritic nickel-cobalt ores. In this research, different extractants were investigated in order to extract scandium from a sulfate medium by a using a solvent extraction method. Generally, the organic extractants are classified as acidic, neutral and basic organophosphorus compounds. However, in solvent extraction of scandium, the acidic and neutral organophosphorus compounds are preferred due to their higher extraction efficiencies. Thus, the aim of the present study was to compare the scandium extraction efficiencies of some acidic and neutral organic reagents. For this reason, Ionquest 290 (Bis(2,4,4-trimethylpenthyl phosphonic acid, DEHPA (Di(2-ethylhexyl phosphoric acid, Cyanex 272 ((Bis(2,4,4-trimethylpentyl phosphinic acid which are acidic organophosphorus compounds, and Cyanex 923 (Trialkylphosphine oxide, which is a neutral organophosphorus compound, were used. The extraction capacities of these organics were studied with respect to the extractant concentration at same pH and phase ratio. As a result of the study, DEHPA was found to have higher scandium extraction efficiency with lower iron extraction at pH = 0.55 at a phase ratio of 10:1 = A:O.

  15. Correlation between stoichiometry and properties of scandium oxide films prepared by reactive magnetron sputtering

    Science.gov (United States)

    Belosludtsev, Alexandr; Juškevičius, Kęstutis; Ceizaris, Lukas; Samuilovas, Romanas; Stanionytė, Sandra; Jasulaitienė, Vitalija; Kičas, Simonas

    2018-01-01

    Scandium oxide films were deposited on fused silica substrates by reactive pulsed DC magnetron sputtering. The use of feed-back optical emission monitoring enabled high-rate reactive deposition of films with tunable stoichiometry and properties. The under-stoichiometric, stoichiometric and over-stoichiometric scandium oxide films were prepared. The compressive stress in films was between 235 and 530 MPa. We showed that phase structure, density, surface roughness and optical properties of the scandium oxide are affected by the film stoichiometry and deposition conditions. Transparent scandium oxide films were slightly hydrophobic (94 ± 3°), homogeneous with a crystallite size of 20 ± 5 nm. The lowest extinction coefficient 0.7 × 10-3, the highest refractive index 2.08 (both quantities at the wavelength of 355 nm) and the highest density 4.1 ± 0.1 g cm-3 exhibited film prepared with the stoichiometric composition. Stoichiometric scandium oxide can be used in various optical applications as high refractive index and wide bandgap material. Transitions to under- or over-stoichiometry lead to a decrease of film density, refractive index and increase of the extinction coefficient.

  16. Mossbauer investigation of scandium oxide-hematite nanoparticles

    Science.gov (United States)

    Allwes, Mark; Sorescu, Monica

    Scandium oxide-doped hematite, xSc2O3*(1-x)alpha-Fe2O3 with molar concentration x =0.1, 0.3, and 0.5 was prepared by using ball milling, taking samples at times 0, 2, 4, 8, and 12 hours. The resulting Mossbauer spectra of the nanoparticles systems were parameterized using NORMOS-90. For each concentration, the spectra at 0 hours only consisted of 1 sextet, as the substitution of Sc2O3into Fe2O3 did not appear until after 2 hours of ball milling time (BMT). Concentration x =0.1 at BMT 2hours consisted of 2 sextets while x =0.3 and 0.5 were fit with 1 sextet and 1 quadrupole-split doublet. Concentration x =0.1 at BMT 4 and 8 hours consisted of 3 sextets, and at BMT 12 hours consisted of 4 sextets. For concentrations x =0.3 and 0.5 at BMT 4, 8, and 12 hours the spectra were fit with 3 sextets and 1 quadrupole-split doublet. With increasing initial concentration, the appearance of the quadrupole-split doublet became more pronounced, indicating the substitution of Fe into Sc2O3 occurred. But for x =0.1, the BMT did influence the number of sextets needed, causing an increase in substitution of Sc2O3 into Fe2O3.

  17. Association between toenail scandium levels and risk of acute myocardial infarction in European men: The EURAMIC and Heavy Metals Study

    NARCIS (Netherlands)

    Gómez-Aracena, J.; Martin-Moreno, J.M.; Riemersma, R.A.; Bode, P.; Gutiérrez-Bedmar, M.; Gorgojo, L.; Kark, J.D.; Garcia-Rodríguez, A.; Gomez-Gracia, E.; Kardinaal, A.F.M.; Aro, A.; Veer, P. van 't; Wedel, H.; Kok, F.J.; Fernández-Crehuet, J.

    2002-01-01

    The association between scandium status and risk of acute myocardial infarction (MI) was examined in a multicentre case control study in 10 centres from Europe and Israel. Scandium in toenails was assessed in 684 cases and 724 controls less than 70 years of age. Mean concentrations of toenail

  18. In-source laser spectroscopy developments at TRILIS-towards spectroscopy on actinium and scandium

    Energy Technology Data Exchange (ETDEWEB)

    Raeder, Sebastian, E-mail: raeder@triumf.ca; Dombsky, Marik; Heggen, Henning; Lassen, Jens; Quenzel, Thomas [TRIUMF, Canada' s National Laboratory for Nuclear and Particle Physics (Canada); Sjoedin, Marica [GANIL (France); Teigelhoefer, Andrea [TRIUMF, Canada' s National Laboratory for Nuclear and Particle Physics (Canada); Wendt, Klaus [Johannes Gutenberg-Universitaet Mainz, Institut fuer Physik (Germany)

    2013-04-15

    Resonance Ionization Laser Ion Sources (RILIS) have become a versatile tool for production and study of exotic nuclides at Isotope Separator On-Line (ISOL) facilities such as ISAC at TRIUMF. The recent development and addition of a grating tuned spectroscopy laser to the TRIUMF RILIS solid state laser system allows for wide range spectral scans to investigate atomic structures on short lived isotopes, e.g., those from the element actinium, produced in uranium targets at ISAC. In addition, development of new and improved laser ionization schemes for rare isotope production at ISAC is ongoing. Here spectroscopic studies on bound states, Rydberg states and autoionizing (AI) resonances on scandium using the existing off-line capabilities are reported. These results allowed to identify a suitable ionization scheme for scandium via excitation into an autoionizing state at 58,104 cm{sup - 1} which has subsequently been used for ionization of on-line produced exotic scandium isotopes.

  19. 49 CFR 173.162 - Gallium.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Gallium. 173.162 Section 173.162 Transportation... PACKAGINGS Non-bulk Packaging for Hazardous Materials Other Than Class 1 and Class 7 § 173.162 Gallium. (a) Except when packaged in cylinders or steel flasks, gallium must be packaged in packagings which meet the...

  20. Process and Mechanical Properties: Applicability of a Scandium modified Al-alloy for Laser Additive Manufacturing

    Science.gov (United States)

    Schmidtke, K.; Palm, F.; Hawkins, A.; Emmelmann, C.

    The applicability of an aluminium alloy containing scandium for laser additive manufacturing (LAM) is considered. Modified aluminium alloys with a scandium content beyond the eutectic point offer great potential to become a high prioritized aerospace material. Depending on other alloying elements like magnesium or zirconium, strongly required weight reduction, corrosion resistance and improved strength properties of metallic light weight alloys can be achieved. The development, production and testing of parts built up by a laser powder bed process will be presented with regard to the qualification of the new material concept "ScalmalloyRP®" for laser additive manufacturing.

  1. Surface roughness and morphologic changes of zirconia: Effect of ...

    African Journals Online (AJOL)

    Purpose: The purpose of this study was to investigate the surface roughness and morphologic changes of pre.sintered ZrO2 after sandblasting and erbium, chromium: Yttrium, scandium, gallium, garnet (Er, Cr: YSGG) laser application of different intensities. Material and Methods: Eighty pre-sintered ZrO2 cylinders (7 mm ...

  2. Synthesis and structural characterization of scandium SALEN complexes.

    Science.gov (United States)

    Meermann, Christian; Sirsch, Peter; Törnroos, Karl W; Anwander, Reiner

    2006-02-28

    A series of heteroleptic scandium SALEN complexes, [(SALEN)Sc(mu-Cl)]2 and (SALEN)Sc[N(SiHMe2)2] is obtained via amine elimination reactions using [Sc(N(i)Pr2)2(mu-Cl)(THF)]2 and Sc[N(SiHMe2)2]3(THF) as metal precursors, respectively. H(2)SALEN ligand precursors comprising H2Salen [(1,2-ethandiyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol], H2Salpren [(2,2-dimethylpropanediyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol], H2Salcyc [(1R,2R)-(-)-1,2-cyclohexanediyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol] and H2Salphen [((1S,2S)-(-)-1,2-diphenylethandiyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol] are selected according to solubility and ligand backbone variation ("=N-(R)-N=" bite angle) criteria. Consideration is given to the feasibility of [Cl --> NR2] and [N(SiHMe2)2--> OSiR3] secondary ligand exchange reactions. X-ray crystal structure analyses of donor-free (Salpren)Sc(N(i)Pr2), (R,R)-(Salcyc)Sc[N(SiHMe2)2], (Salen)Sc(OSi(t)BuPh2) and (Salphen)Sc(OSiH(t)Bu2) reveal (i) a very short Sc-N bond distance of 2.000(3) A, (ii) weak beta(Si-H)(amido)-Sc agostic interactions and (iii) an exclusive intramolecularly tetradentate and intrinsically bent coordination mode of the SALEN ligands with angle(Ph,Ph) dihedral angles and Sc-[N(2)O(2)] distances in the 124.27(9)-127.7(3) degrees and 0.638(1)-0.688(1) A range, respectively.

  3. Scandium SALEN complexes bearing chloro, aryloxo, and hydroxo ligands.

    Science.gov (United States)

    Meermann, Christian; Törnroos, Karl W; Anwander, Reiner

    2009-03-16

    Heteroleptic amide complexes (SALEN)Sc[N(SiHMe(2))(2)] (SALEN = Salen(tBu,tBu), Salcyc(tBu,tBu), or Salpren(tBu,tBu) if not stated differently) were examined as synthesis precursors according to silylamine elimination reactions. Treatment of (SALEN)Sc[N(SiHMe(2))(2)] with H(2)O or phenols (HOAr(R,R); R = tBu, iPr) afforded complexes [(SALEN)Sc(mu-OH)](2) and (SALEN)Sc(OAr(R,R)), while chloro exchange products were formed from the respective reactions with NH(4)Cl or AlMe(2)Cl. Such complexes [(SALEN)Sc(mu-Cl)](2) and (SALEN)ScCl(thf) were also obtained by utilizing alternative synthesis protocols, allowing for controlled donor absence and presence. Heteroleptic amide precursors [Sc(NiPr(2))(2)(mu-Cl)(thf)](2) and [Sc[N(SiHMe(2))(2)](2)(mu-Cl)(thf)](2) readily undergo amine elimination reactions with H(2)SALEN derivatives to form the corresponding chloride complexes. Spectroscopic and X-ray structural data of the heteroleptic scandium complexes revealed an exclusive intramolecular tetradentate coordination mode of the SALEN ligands independent of the SALEN ligand bite angle and the nature of the "second" ligand (chloro, amido, aryloxo, hydroxo). The coordination of the SALEN ligands is rationalized on the basis of (a) the displacement d of the metal center from the [N(2)O(2)] least-squares plane, (b) the dihedral angle alpha between the phenyl rings of the salicylidene moieties, and (c) the angle beta = Ct-Ln-Ct (Ct = centroid of the phenyl rings) in the case of strongly twisted ligands.

  4. Vertical distribution of scandium in the north central Pacific

    Science.gov (United States)

    Amakawa, Hiroshi; Nomura, Miho; Sasaki, Kazunori; Oura, Yasuji; Ebihara, Mitsuru

    2007-06-01

    The concentrations of scandium (Sc) in seawater, which have remained unreported since the early 1970s, were determined together with those of yttrium (Y) and lanthanides (Ln) with samples from the north central Pacific Ocean (St. BO-3). The Sc concentration shows a so-called nutrient-like profile: it increases gradually from the surface (about 2 pmol/kg) to the ocean floor (about 20 pmol/kg). That pattern closely resembles those of Y and Ln (correlation coefficient (r) > 0.92). Some light-to-middle Ln (Pr-Tb) exhibit a closer correlation with Sc than do Y, La, or heavy Ln (Ho-Lu). In contrast, Y/Sc and Ln/Sc ratios (elemental abundance ratios) indicate that Sc is depleted compared to either Y or Ln in seawater more than in loess, which represents chemical compositions of crustal material. These observations offer a conflicting view of chemical reactivity related Y, Ln, and Sc: r values show that the chemical reactivity of Sc resembles those of Y and Ln, but differences of Y/Sc and Ln/Sc ratios in seawater and in loess suggest that the chemical reactivity of Sc differs from those of Y and Ln. More Sc data for seawater are necessary to clarify the chemical reactivity of Sc in the ocean. We also propose that comparative studies of vertical profiles of Sc and such elements as Fe, Ti, Zr, and Hf showing so-called nutrient-like profiles at the same oceanic stations would be helpful and effective for clarifying the behavior of Sc in the ocean.

  5. Medical Applications and Toxicities of Gallium Compounds

    Science.gov (United States)

    Chitambar, Christopher R.

    2010-01-01

    Over the past two to three decades, gallium compounds have gained importance in the fields of medicine and electronics. In clinical medicine, radioactive gallium and stable gallium nitrate are used as diagnostic and therapeutic agents in cancer and disorders of calcium and bone metabolism. In addition, gallium compounds have displayed anti-inflammatory and immunosuppressive activity in animal models of human disease while more recent studies have shown that gallium compounds may function as antimicrobial agents against certain pathogens. In a totally different realm, the chemical properties of gallium arsenide have led to its use in the semiconductor industry. Gallium compounds, whether used medically or in the electronics field, have toxicities. Patients receiving gallium nitrate for the treatment of various diseases may benefit from such therapy, but knowledge of the therapeutic index of this drug is necessary to avoid clinical toxicities. Animals exposed to gallium arsenide display toxicities in certain organ systems suggesting that environmental risks may exist for individuals exposed to this compound in the workplace. Although the arsenic moiety of gallium arsenide appears to be mainly responsible for its pulmonary toxicity, gallium may contribute to some of the detrimental effects in other organs. The use of older and newer gallium compounds in clinical medicine may be advanced by a better understanding of their mechanisms of action, drug resistance, pharmacology, and side-effects. This review will discuss the medical applications of gallium and its mechanisms of action, the newer gallium compounds and future directions for development, and the toxicities of gallium compounds in current use. PMID:20623028

  6. Medical Applications and Toxicities of Gallium Compounds

    Directory of Open Access Journals (Sweden)

    Christopher R. Chitambar

    2010-05-01

    Full Text Available Over the past two to three decades, gallium compounds have gained importance in the fields of medicine and electronics. In clinical medicine, radioactive gallium and stable gallium nitrate are used as diagnostic and therapeutic agents in cancer and disorders of calcium and bone metabolism. In addition, gallium compounds have displayed anti-inflammatory and immunosuppressive activity in animal models of human disease while more recent studies have shown that gallium compounds may function as antimicrobial agents against certain pathogens. In a totally different realm, the chemical properties of gallium arsenide have led to its use in the semiconductor industry. Gallium compounds, whether used medically or in the electronics field, have toxicities. Patients receiving gallium nitrate for the treatment of various diseases may benefit from such therapy, but knowledge of the therapeutic index of this drug is necessary to avoid clinical toxicities. Animals exposed to gallium arsenide display toxicities in certain organ systems suggesting that environmental risks may exist for individuals exposed to this compound in the workplace. Although the arsenic moiety of gallium arsenide appears to be mainly responsible for its pulmonary toxicity, gallium may contribute to some of the detrimental effects in other organs. The use of older and newer gallium compounds in clinical medicine may be advanced by a better understanding of their mechanisms of action, drug resistance, pharmacology, and side-effects. This review will discuss the medical applications of gallium and its mechanisms of action, the newer gallium compounds and future directions for development, and the toxicities of gallium compounds in current use.

  7. Thermally induced transparency for short spin wave pulses in yttrium iron garnet (YIG) films

    Science.gov (United States)

    Ordonez Romero, Cesar Leonardo; Kolokoltsev, Oleg; Gomez Arista, Ivan; Qureshi, Naser; Monsiváis Galindo, Guillermo; Vargas Hernández, Hesiquio

    2014-03-01

    The compensation of spin wave propagation losses plays a very important role in the development of novel magnonic devices. Up to now, however, most of the known amplification methods present relative narrow frequency bandwidths due to their resonant nature. In this work, we present compensation of the propagation losses or pseudo-amplification of travelling spin waves by tailoring the bias magnetic field profile. The thermally-induced non-uniform profile of the magnetization introduced on an Yttrium Iron Garnet (YIG) thin film by a localized spot of a cw argon-ion laser creates the conditions to observe the complete compensation of the spin wave propagation losses. The spin wave evolution was mapped with a time and spaced resolved inductive magneto-dynamic prove system. The experiment was carried out using a uniform sample of single-crystal YIG film grown on a gallium-gadolinium garnet (GGG) substrate. The 2mm-wide, 20mm-long and 6microns-thick YIG strip was saturated with an external magnetic field enabling the set up for the propagation of magneto-static surface waves. This work was supported by the UNAM-DGAPA-PAPIIT IA100413.

  8. Sub-micrometer yttrium iron garnet LPE films with low ferromagnetic resonance losses

    Science.gov (United States)

    Dubs, Carsten; Surzhenko, Oleksii; Linke, Ralf; Danilewsky, Andreas; Brückner, Uwe; Dellith, Jan

    2017-05-01

    Using a liquid phase epitaxy (LPE) technique (1 1 1) yttrium iron garnet (YIG) films with thicknesses of  ≈100 nm and surface roughnesses as low as 0.3 nm have been grown on (1 1 1) gadolinium gallium garnet (GGG) substrates as a basic material for spin-wave propagation experiments in microstructured waveguides. The continuously strained films exhibit nearly perfect crystallinity without significant mosaicity and with effective lattice misfits of Δ {{a}\\bot}/{{a}s}≈ {{10}-4} and below. The film/substrate interface is extremely sharp without broad interdiffusion layer formation. All LPE films exhibit a nearly bulk-like saturation magnetization of (1800+/- 20 ) Gs and an ‘easy cone’ anisotropy type with extremely small in-plane coercive fields  <0.2 Oe. There is a rather weak in-plane magnetic anisotropy with a pronounced six-fold symmetry observed for the saturation field  <1.5 Oe. No significant out-of-plane anisotropy is observed, but a weak dependence of the effective magnetization on the lattice misfit is detected. The narrowest ferromagnetic resonance linewidth is determined to be 1.4 Oe @ 6.5 GHz which is the lowest value reported so far for YIG films of 100 nm thicknesses and below. The Gilbert damping coefficient for investigated LPE films is estimated to be close to 1× {{10}-4} .

  9. FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS): An Artificially Garnet Crystal Materials Using In Terahertz Waveguide

    Science.gov (United States)

    Yang, Qing-Hui; Zhang, Huai-Wu; Liu, Ying-Li; Wen, Qi-Ye; Zha, Jie

    2008-11-01

    A hypothesis is brought forward that the materials with low propagation loss in both optical and microwave band may exhibit good performance in terahertz (THz) band because THz wave band interspaces those two wave bands. For the purpose of exploring a kind of low-loss material for THz waveguide, Lu2.1Bi0.9Fe5O12 (LuBilG) garnet films are prepared by liquid phase epitaxy (LPE) method on a gadolinium gallium garnet (GGG) substrate from lead-free flux because of the good properties in both optical and microwave bands. In microwave band, the ferromagnetic resonance (FMR) linewidth of the film 2ΔH = 2.8-5.1 Oe; in optical band, the optical absorption coefficient is 600 cm-1 at visible range and about 100-170 cm-1 when the wavelength is longer than 800nm. In THz range, our hypothesis is well confirmed by a THz-TDS measurement which shows that the absorbance of the him for THz wave is 0.05-0.3 cm-1 and the minimum value appears at 2.3 THz. This artificial ferromagnetic material holds a great promise for magnetic held tunable THz devices such as waveguide, modulator or switch.

  10. A FETISH for gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    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).

  11. Mineral resource of the month: gallium

    Science.gov (United States)

    Jaskula, Brian W.

    2009-01-01

    The metal element gallium occurs in very small concentrations in rocks and ores of other metals — native gallium is not known. As society gets more and more high-tech, gallium becomes more useful. Gallium is one of only five metals that are liquid at or close to room temperature. It has one of the longest liquid ranges of any metal (29.8 degrees Celsius to 2204 degrees Celsius) and has a low vapor pressure even at high temperatures. Ultra-pure gallium has a brilliant silvery appearance, and the solid metal exhibits conchoidal fracture similar to glass.

  12. Oligonuclear gallium nitrogen cage compounds: molecular intermediates on the way from gallium hydrazides to gallium nitride.

    Science.gov (United States)

    Uhl, Werner; Abel, Thomas; Hagemeier, Elke; Hepp, Alexander; Layh, Marcus; Rezaeirad, Babak; Luftmann, Heinrich

    2011-01-03

    Gallium hydrazides are potentially applicable as facile starting compounds for the generation of GaN by thermolysis. The decomposition pathways are, however, complicated and depend strongly on the substituents attached to the gallium atoms and the hydrazido groups. This paper describes some systematic investigations into the thermolysis of the gallium hydrazine adduct Bu(t)(3)Ga←NH(2)-NHMe (1a) and the dimeric gallium hydrazides [R(2)Ga(N(2)H(2)R')](2) (2b, R = Bu(t), R' = Bu(t); 2c, R = Pr(i), R' = Ph; 2d, R = Me, R' = Bu(t)) which have four- or five-membered heterocycles in their molecular cores. Heating of the adduct 1a to 170 °C gave the heterocyclic compound Bu(t)(2)Ga(μ-NH(2))[μ-N(Me)-N(=CH(2))]GaBu(t)(2) (3) by cleavage of N-N bonds and rearrangement. 3 was further converted at 400 °C into the tetrameric gallium cyanide (Bu(t)(2)GaCN)(4) (4). The thermolysis of the hydrazide (Bu(t)(2)Ga)(2)(NH-NHBu(t))(2) (2b) at temperatures between 270 and 420 °C resulted in cleavage of all N-N bonds and the formation of an octanuclear gallium imide, (Bu(t)GaNH)(8) (6). The trimeric dialkylgallium amide (Bu(t)(2)GaNH(2))(3) (5) was isolated as an intermediate. Thermolysis of the hydrazides (Pr(i)(2)Ga)(2)(NH-NHPh)(NH(2)-NPh) (2c) and (Me(2)Ga)(2)(NH-NHBu(t))(2) (2d) proceeded in contrast with retention of the N-N bonds and afforded a variety of novel gallium hydrazido cage compounds with four gallium atoms and up to four hydrazido groups in a single molecule: (Pr(i)Ga)(4)(NH-NPh)(3)NH (7), (MeGa)(4)(NH-NBu(t))(4) (8), (MeGa)(4)(NH-NBu(t))(3)NBu(t) (9), and (MeGa)(4)(NHNBu(t))(3)NH (10). Partial hydrolysis gave reproducibly the unique octanuclear mixed hydrazido oxo compound (MeGa)(8)(NHNBu(t))(4)O(4) (11).

  13. In situ observation of the reaction of scandium and carbon by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Juarez-Arellano, Erick A., E-mail: eajuarez@unpa.edu.m [Institut fuer Geowissenschaften, Universitaet Frankfurt, Altenhoeferallee 1, 60438 Frankfurt a.M. (Germany); Universidad del Papaloapan, Circuito Central 200, Parque Industrial, Tuxtepec 68301 (Mexico); Winkler, Bjorn [Institut fuer Geowissenschaften, Universitaet Frankfurt, Altenhoeferallee 1, 60438 Frankfurt a.M. (Germany); Vogel, Sven C. [Los Alamos National Laboratory, Lujan Center. Mail Stop H805, Los Alamos, NM 87545 (United States); Senyshyn, Anatoliy [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universitaet Muenchen, Lichtenbergstr. 1, D-85747 Garching (Germany); Materialwissenschaft, TU Darmstadt, Petersensstr. 23, D-64287 Darmstadt (Germany); Kammler, Daniel R. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Avalos-Borja, Miguel [CNyN, UNAM, A. Postal 2681, Ensenada, B.C. (Mexico)

    2011-01-05

    Research highlights: {yields} Exist two ScC cubic phases with B1-structure type differing in site occupancy of C. {yields} A new orthorhombic scandium carbide phase is formed at 1473(50) K. {yields} The recrystallization of alpha-Sc occurs between 1000 and 1223 K. - Abstract: The formation of scandium carbides by reaction of the elements has been investigated by in situ neutron diffraction up to 1823 K. On heating, the recrystallization of {alpha}-Sc occurs between 1000 and 1223 K. The formation of Sc{sub 2}C and ScC (NaCl-B1 type structure) phases has been detected at 1323 and 1373 K, respectively. The formation of a new orthorhombic scandium carbide phase was observed at 1473(50) K. Once the scandium carbides are formed they are stable upon heating or cooling. No other phases were detected in the present study, in which the system was always carbon saturated. The thermal expansion coefficients of all phases have been determined, they are constant throughout the temperature interval studied.

  14. The effects of aluminum or scandium on the toughness, density and ...

    African Journals Online (AJOL)

    The effects of the substitution of aluminum or scandium on the density, toughness as well as the stability of the phases formed by such an addition on platinum, iridium, rhodium and palladium metals were evaluated with the density functional quantum mechanical calculation methods. All the metals had four atoms per ...

  15. Common features of gallium perovskites

    NARCIS (Netherlands)

    Aleksiyko, R; Berkowski, M; Byszewski, P; Dabrowski, B; Diduszko, R; Fink-Finowicki, J; Vasylechko, LO

    2001-01-01

    The Czochralski and floating zone methods have been used to grow single crystals of gallium perovskites solid solutions with rare earth elements La, Pr, Nd, Sm and with Sr. The structure of the crystals has been investigated by powder X-ray, synchrotron radiation and neutron diffraction methods over

  16. Gallium scan in intracerebral sarcoidosis

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. P-type gallium nitride

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  19. Chemical and biological evaluation of scandium(III)-polyaminopolycarboxylate complexes as potential PET agents and radiopharmaceuticals

    Energy Technology Data Exchange (ETDEWEB)

    Huclier-Markai, S.; Sabatie, A.; Ribet, S. [Univ. de Nantes (France). Lab. Subatech; Kubicek, V.; Hermann, P. [Charles Univ., Prague (Czech Republic). Dept. of Inorganic Chemistry; Paris, M. [Univ. de Nantes (France). Inst. des Materiaux; Vidaud, C. [CEA/DSV/iBEB/SBTN, Bagnols sur Ceze (France). Lab. d' Etude des Proteines Cibles; Cutler, C.S. [Univ. of Missouri, Columbia, MO (United States). Reserach Reactor Center

    2011-07-01

    Scandium isotopes ({sup 44}Sc, {sup 47}Sc) are more available and their properties are convenient for either PET imaging or radiotherapy. To use them in nuclear medicine, ligands forming complexes with a high stability are necessary. Available experimental data on stability constants for complexes of ligands such as EDTA, DTPA, DOTA, NOTA and TETA with various metal ions have been published. But scandium is the exception since scarce data is available in the literature. Values of stability constants of Sc(III) with the ligands were determined by free-ion selective radiotracer extraction, complemented by {sup 45}Sc NMR and potentiometry data. The thermodynamic stability of the Sc-complexes increases in the order TETA < NOTA < EDTA < DTPA < DOTA. The in vitro stability of the Sc(III) complexes was studied in the presence of hydroxyapatite and rat serum to estimate their in vivo stability. The most stable complex was shown to be Sc-DOTA.

  20. Pure spin current transport in gallium doped zinc oxide

    Science.gov (United States)

    Althammer, Matthias; Mukherjee, Joynarayan; Geprägs, Stephan; Goennenwein, Sebastian T. B.; Opel, Matthias; Ramachandra Rao, M. S.; Gross, Rudolf

    2017-01-01

    We study the flow of a pure spin current through zinc oxide by measuring the spin Hall magnetoresistance (SMR) in thin film trilayer samples consisting of bismuth-substituted yttrium iron garnet (Bi:YIG), gallium-doped zinc oxide (Ga:ZnO), and platinum. We investigate the dependence of the SMR magnitude on the thickness of the Ga:ZnO interlayer and compare to a Bi:YIG/Pt bilayer. We find that the SMR magnitude is reduced by almost one order of magnitude upon inserting a Ga:ZnO interlayer and continuously decreases with increasing interlayer thickness. Nevertheless, the SMR stays finite even for a 12 nm thick Ga:ZnO interlayer. These results show that a pure spin current indeed can propagate through a several nm-thick degenerately doped zinc oxide layer. We also observe differences in both the temperature and the field dependence of the SMR when comparing tri- and bilayers. Finally, we compare our data to the predictions of a model based on spin diffusion. This shows that interface resistances play a crucial role for the SMR magnitude in these trilayer structures.

  1. Precipitation behaviour and recrystallisation resistance in aluminum alloys with additions of hafnium, scandium and zirconium

    OpenAIRE

    Hallem, Håkon

    2005-01-01

    The overall objective of this work has been to develop aluminium alloys, which after hot and cold deformation are able to withstand high temperatures without recrystallising. This has been done by investigating aluminium alloys with various additions of hafnium, scandium and zirconium, with a main focus on Hf and to which extent it may partly substitute or replace Zr and/or Sc as a dispersoid forming elements in these alloys. What is the effect of hafnium, alone and in combination with Zr...

  2. Nonlinear FMR spectra in yttrium iron garnet

    Directory of Open Access Journals (Sweden)

    Yu.M. Bunkov, P.M. Vetoshko, I.G. Motygullin, T.R. Safin, M.S. Tagirov, N.A. Tukmakova

    2015-12-01

    Full Text Available Results of demagnetizing effect studies in yttrium iron garnet Y3Fe5O12 thin films are reported. Experiments were performed on X-Band of electron paramagnetic resonance spectrometer at room temperature. The ferromagnetic resonance (FMR spectra were obtained for one-layer single crystal YIG films for different values of the applied microwave power. Nonlinear FMR spectra transformation by the microwave power increasing in various directions of magnetic field sweep was observed. It is explained by the influence of the demagnetization action of nonequilibrium magnons.

  3. Pilot-scale recovery of rare earths and scandium from phosphogypsum and uranium leachates

    Directory of Open Access Journals (Sweden)

    Mashkovtsev Maxim

    2016-01-01

    Full Text Available Ural Federal University (UrFU and VTT have performed joint research on development of industrial technologies for the extraction of REM and Scandium compounds from phosphogypsum and Uranium ISL leachate solutions. Leaching-absorption experiments at UrFU have been supported with multicomponent solution modelling by VTT. The simulations have been performed with VTT’s ChemSheet/Balas program and can be used for speciation calculations in the lixiviant solution. The experimental work combines solvent extraction with advanced ion exchange methodology in a pilot facility capable of treating 5 m3 solution per hour. Currently, the plant produces cerium carbonate, lanthanum oxide, neodymium oxide and concentrate of heavy rare earth metals. A batch of 45 t solids has been processed with the gain of 100 kg’s of REM concentrate. A mini-pilot plant with productivity above 50 liters per hour has been applied to recover scandium oxide and REE concentrates from the uranium ISL solution. As the preliminary product contains radioactivity (mainly strontium, an additional decontamination and cleaning of both concentrates by extraction has rendered a necessity. Finally a purified 99% concentrate of scandium oxide as well as 99% rare earth concentrate are received.

  4. Optimization of scandium oxide growth by high pressure sputtering on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Feijoo, P.C., E-mail: pedronska@fis.ucm.es; Pampillon, M.A.; San Andres, E.; Lucia, M.L.

    2012-12-30

    This work demonstrates the viability of scandium oxide deposition on silicon by means of high pressure sputtering. Deposition pressure and radio frequency power are varied for optimization of the properties of the thin films and the ScO{sub x}/Si interface. The physical characterization was performed by ellipsometry, Fourier transform infrared spectroscopy, x-ray diffraction and transmission electron microscopy. Aluminum gate electrodes were evaporated for metal-insulator-semiconductor (MIS) fabrication. From the electrical characterization of the MIS devices, the density of interfacial defects is found to decrease with deposition pressure, showing a reduced plasma damage of the substrate surface for higher pressures. This is also supported by lower flatband voltage shifts in the capacitance versus voltage hysteresis curves. Sputtering at high pressures (above 100 Pa) reduces the interfacial SiO{sub x} formation, according to the infrared spectra. The growth rates decrease with deposition pressure, so a very accurate control of the layer thicknesses could be provided. - Highlights: Black-Right-Pointing-Pointer Scandium oxide is considered as a high permittivity dielectric. Black-Right-Pointing-Pointer Scandium oxide was deposited on Si by high pressure sputtering. Black-Right-Pointing-Pointer Characterization was performed for deposition condition optimization. Black-Right-Pointing-Pointer High deposition pressures showed higher film and interface quality.

  5. XAFS spectroscopic study of Ti coordination in garnet

    Energy Technology Data Exchange (ETDEWEB)

    Ackerson, Michael R.; Tailby, Nicholas D.; Watson, E. Bruce

    2017-01-01

    Titanium can be incorporated either tetrahedrally (IVTi) or octahedrally (VITi) in most silicate minerals. Ti K-edge X-ray absorption fine structure (XAFS) spectroscopy enables observation of Ti coordination in minerals and melts. In this study, XAFS is used to determine the coordination of Ti in synthetic and natural garnets. Garnets grown synthetically at eclogite- and granulite-facies conditions can contain several wt% TiO2, most of which is incorporated as VITi. This observation aligns with major element trends in these garnets. In natural garnets grown at lower temperatures and pressures, on the other hand, Ti is observed to occupy both the octahedral and tetrahedral sites in garnet—in some cases Ti is almost entirely fourfold coordinated. Combined with previous research (see Ackerson et al. 2017, this issue) on substitution mechanisms for VITi, the results of this study demonstrate that Ti is incorporated on two crystallographic sites in garnet by at least three primary substitution mechanisms. In both natural and synthetic garnets, there is a discernible increase in VITi content in garnet with increasing temperature and pressure, suggesting a significant role for these two parameters in determining Ti solubility. However, a continuous increase in VITi with increasing grossular content also suggests that the Ca content of the garnet plays a critical role.

  6. Lu-Hf and Sm-Nd garnet geochronology

    DEFF Research Database (Denmark)

    Smit, Matthijs Arjen; Scherer, Erik E.; Mezger, Klaus

    2013-01-01

    To investigate the systematics of the 176Lu–176Hf and 147Sm–143Nd garnet chronometers, we performed REE and isotope analyses on garnet crystals of different size (0.55–3.1 mm radius) from a single granulite specimen (Archean Pikwitonei Granulite Domain, Manitoba, Canada). The Lu–Hf dates...

  7. Gallium-67 citrate scan in extrapulmonary tuberculosis

    Energy Technology Data Exchange (ETDEWEB)

    Lin Wanyu [Taichung Veterans General Hospital (Taiwan). Dept. of Nuclear Medicine; Hsieh Jihfang [Chi-Mei Foundation Hospital, Tainan (Taiwan)

    1999-07-01

    Aim: Whole-body gallium scan was performed to evaluate the usefulness of gallium scan for detecting extrapulmonary tuberculosis (TB) lesions. Methods: Thirty-seven patients with extrapulmonary TB were included in this study. Four patients were found to have two lesions. Totally, 41 lesions were identified, including 19 TB arthritis, 8 spinal TB, 5 TB meningitis, 3 TB lymphadenopathy, 2 TB pericarditis, 1 TB peritonitis, 1 intestinal TB, 1 skin TB and 1 renal TB. Results: Of the 41 extrapulmonary TB lesions, gallium scan detected 32 lesions with a sensitivity of 78%. All the patients with TB meningitis showed negative gallium scan. When the five cases of TB meningitis were excluded, the detection sensitivity of gallium scan increased to 88.9% (32/36). Conclusion: Our data revealed that gallium scan is a convenient and useful method for evaluating extrapulmonary TB lesions other than TB-meningitis. We suggest that gallium scan be included in the clinical routine for patients with suspected extrapulmonary TB. (orig.) [German] Ziel: Es wurden Ganzkoerper-Gallium-Szintigramme angefertigt, um den Nutzen der Gallium-Szintigraphie zur Erfassung von extrapulmonalen Tuberkuloseherden (TB) zu erfassen. Methoden: 37 Patienten mit extrapulmonaler TB wurden eingeschlossen. 4 Patienten hatten 2 Laesionen. Insgesamt wurden 41 Laesionen identifiziert, hierunter 19 TB-Arthritis, 8 spinale TB, 5 TB-Meningitis, 3 TB-Lymphadenopathie, 2 TB-Perikarditis, 1 TB-Peritonitis, 1 intestinale TB, 1 Haut-TB und eine Nieren-TB. Ergebnisse: Von den 41 extrapulmonalen TB-Herden erfasste die Gallium-Szintigraphie 32 Herde mit einer Sensitivitaet von 78%. Alle Patienten mit TB-Meningitis zeigten einen negativen Gallium-Scan. Wenn die 5 Faelle mit TB-Meningitis ausgeschlossen wurden, stieg die Sensitivititaet der Gallium-Szintigraphie auf 88,9% (32/36). Schlussfolgerung: Die Daten zeigen, dass die Gallium-Szintigraphie eine einfache und nuetzliche Methode zur Erfassung extrapulmonaler TB-Herde ist

  8. Gallium Electromagnetic (GEM) Thrustor Concept and Design

    Science.gov (United States)

    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.

  9. Magneto-optical properties of yttrium iron garnet (YIG) thin films elaborated by radio frequency sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Boudiar, T. [DIOM Laboratory, Faculty des Sciences, 23 rue du Docteur Paul Michelon, 42023 Saint-Etienne (France)]. E-mail: toufik.boudiar@univ-st-etienne.fr; Payet-Gervy, B. [DIOM Laboratory, Faculty des Sciences, 23 rue du Docteur Paul Michelon, 42023 Saint-Etienne (France); Blanc-Mignon, M.-F. [DIOM Laboratory, Faculty des Sciences, 23 rue du Docteur Paul Michelon, 42023 Saint-Etienne (France); Rousseau, J.-J. [DIOM Laboratory, Faculty des Sciences, 23 rue du Docteur Paul Michelon, 42023 Saint-Etienne (France); Le Berre, M. [LPM, UMR 5511, INSA Lyon, 7 av. Jean Capelle, 69621 Villeurbanne (France); Joisten, H. [CEA-LETI, 17 rue des martyrs, 38041 Grenoble (France)

    2004-12-01

    Thin films of yttrium iron garnet (YIG) are grown by radio frequency magnetron non reactive sputtering system. Thin films are crystallised by heat-treatment to obtain magneto-optical properties. On quartz substrate, the network of cracks observed on the annealed samples can be explained by the difference between the thermal expansion coefficient of substrate and YIG. Physico-chemical analysis shown that the obtained material has a correct stoichiometry and is crystallised as FCC. The Faraday rotation of thin films is measured with a classical ellipsometric system based on transmission which allows us to obtained an accuracy of 0.01 deg. The variation of Faraday rotation is studied on the one hand versus radio frequency power applied to the cathode during the deposition and on the other hand versus the applied magnetic field. The results are compared with those obtained by vibrating sample magnetometer analysis in perpendicular configuration. A maximum Faraday rotation is observed to be 1900 deg./cm at the wavelength of 594nm for a YIG thin film formed on quartz substrate and annealed at 740 deg. C. The values of the Faraday rotation coefficients obtained in the study versus the wavelength are comparable to those of the literature for the bulk material. In order to eliminate the stress due to the heat-treatment, we made some films on single crystals of gadolinium gallium garnet (111) substrates for which thermal expansion coefficient is near than the YIG one. The material crystallises with no crackles and the Faraday effect is equivalent.

  10. Gallium nitride on gallium oxide substrate for integrated nonlinear optics

    KAUST Repository

    Awan, Kashif M.

    2017-11-22

    Gallium Nitride (GaN), being a direct bandgap semiconductor with a wide bandgap and high thermal stability, is attractive for optoelectronic and electronic applications. Furthermore, due to its high optical nonlinearity — the characteristic of all 111-V semiconductors — GaN is also expected to be a suitable candidate for integrated nonlinear photonic circuits for a plethora of apphcations, ranging from on-chip wavelength conversion to quantum computing. Although GaN devices are in commercial production, it still suffers from lack of a suitable substrate material to reduce structural defects like high densities of threading dislocations (TDs), stacking faults, and grain boundaries. These defects significandy deteriorate the optical quality of the epi-grown GaN layer, since they act as non-radiative recombination centers. Recent studies have shown that GaN grown on (−201) β-Gallium Oxide (Ga2O3) has superior optical quality due to a better lattice matching as compared to GaN grown on Sapphire (Al2O3) [1-3]. In this work, we report on the fabrication of GaN waveguides on GaiOj substrate and their optical characterization to assess their feasibihty for efficient four-wave mixing (FWM).

  11. Indium gallium nitride multijunction solar cell simulation using silvaco atlas

    OpenAIRE

    Garcia, Baldomero

    2007-01-01

    This thesis investigates the potential use of wurtzite Indium Gallium Nitride as photovoltaic material. Silvaco Atlas was used to simulate a quad-junction solar cell. Each of the junctions was made up of Indium Gallium Nitride. The band gap of each junction was dependent on the composition percentage of Indium Nitride and Gallium Nitride within Indium Gallium Nitride. The findings of this research show that Indium Gallium Nitride is a promising semiconductor for solar cell use. United...

  12. Recovery of Scandium from Leachate of Sulfation-Roasted Bayer Red Mud by Liquid-Liquid Extraction

    Science.gov (United States)

    Liu, Zhaobo; Li, Hongxu; Jing, Qiankun; Zhang, Mingming

    2017-11-01

    The leachate obtained from sulfation-roasted Bayer red mud is suitable for extraction of scandium by liquid-liquid solvent extraction because it contains trace amounts of Fe3+ and Si4+. In this study, a completely new metallurgical process for selective recovery of scandium from Bayer red mud was proposed. The extraction performances of Sc3+, Fe3+, Al3+, Si4+, Ca2+, and Na+ from synthetic leachate of sulfation-roasted red mud were first investigated using organophosphorus extractants (di-2-ethylhexyl phosphoric acid P204 and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester P507) and carboxylic acid extractant (Versatic acid 10). It shows that P204 has an excellent extraction ability and that it can be applied to the scandium recovery. P507 and Versatic acid 10 are much poorer in performance for selective extraction of scandium. In the leachate of sulfation-roasted red mud, approximately 97% scandium can be recovered using a P204/sulfonated kerosene (1% v/v) extraction system under the condition of an organic-to-aqueous phase ratio of 10:1 and with an extraction temperature of 15°C.

  13. Temperature dependence of the magnon spin diffusion length and magnon spin conductivity in the magnetic insulator yttrium iron garnet

    Science.gov (United States)

    Cornelissen, L. J.; Shan, J.; van Wees, B. J.

    2016-11-01

    We present a systematic study of the temperature dependence of diffusive magnon spin transport using nonlocal devices fabricated on a 210-nm yttrium iron garnet film on a gadolinium gallium garnet substrate. In our measurements, we detect spin signals arising from electrical and thermal magnon generation, and we directly extract the magnon spin diffusion length λm for temperatures from 2 to 293 K. Values of λm obtained from electrical and thermal generation agree within the experimental error with λm=9.6 ±0.9 μ m at room temperature to a minimum of λm=5.5 ±0.7 μ m at 30 K. Using a two-dimensional finite element model to fit the data obtained for electrical magnon generation we extract the magnon spin conductivity σm as a function of temperature, which is reduced from σm=3.7 ±0.3 ×105S /m at room temperature to σm=0.9 ±0.6 ×104S /m at 5 K. Finally, we observe an enhancement of the signal originating from thermally generated magnons for low temperatures where a maximum is observed around T =7 K . An explanation for this low-temperature enhancement is however still missing and requires additional investigation.

  14. Nonreciprocity of spin waves in magnonic crystals created by surface acoustic waves in structures with yttrium iron garnet

    Science.gov (United States)

    Kryshtal, R. G.; Medved, A. V.

    2015-12-01

    Experimental results of investigations of nonreciprocity for surface magnetostatic spin waves (SMSW) in the magnonic crystal created by surface acoustic waves (SAW) in yttrium iron garnet films on a gallium gadolinium garnet substrate as without metallization and with aluminum films with different electrical conductivities (thicknesses) are presented. In structures without metallization, the frequency of magnonic gaps is dependent on mutual directions of propagation of the SAW and SMSW, showing nonreciprocal properties for SMSW in SAW - magnonic crystals even with the symmetrical dispersion characteristic. In metalized SAW - magnonic crystals the shift of the magnonic band gaps frequencies at the inversion of the biasing magnetic field was observed. The frequencies of magnonic band gaps as functions of SAW frequency are presented. Measured dependencies, showing the decrease of magnonic gaps frequency and the expansion of the magnonic band gap width with the decreasing of the metal film conductivity are given. Such nonreciprocal properties of the SAW - magnonic crystals are promising for signal processing in the GHz range.

  15. Transparent ceramic garnet scintillator optimization via composition and co-doping for high-energy resolution gamma spectrometers (Conference Presentation)

    Science.gov (United States)

    Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Beck, Patrick R.; Swanberg, Erik L.; Hunter, Steven L.

    2016-09-01

    Breakthrough energy resolution, R(662keV) Gadolinium Yttrium Gallium Aluminum Garnet, or GYGAG(Ce), by optimizing fabrication conditions. Here we describe the dependence of scintillation light yield and energy resolution on several variables: (1) Stoichiometry, in particular Gd/Y and Ga/Al ratios which modify the bandgap energy, (2) Processing methods, including vacuum vs. oxygen sintering, and (3) Trace co-dopants that influence the formation of Ce4+ and modify the intra-bandgap trap distribution. To learn about how chemical composition influences the scintillation properties of transparent ceramic garnet scintillators, we have measured: scintillation decay component 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. Optimized GYGAG(Ce) provides R(662 keV) =3.0%, for 0.05 cm3 size ceramics with Silicon photodiode readout, and R(662 keV) =4.6%, at 2 in3 size with PMT readout.

  16. Thin yttrium iron garnet films grown by pulsed laser deposition: Crystal structure, static, and dynamic magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Sokolov, N. S., E-mail: nsokolov@fl.ioffe.ru; Fedorov, V. V.; Korovin, A. M.; Suturin, S. M.; Baranov, D. A.; Gastev, S. V.; Krichevtsov, B. B.; Bursian, V. E.; Lutsev, L. V. [Ioffe Physical-Technical Institute of Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Maksimova, K. Yu.; Grunin, A. I. [Immanuel Kant Baltic Federal University, Kaliningrad 236041 (Russian Federation); Tabuchi, M. [Synchrotron Radiation Research Center, Nagoya University, Nagoya 464-8603 (Japan)

    2016-01-14

    Pulsed laser deposition has been used to grow thin (10–84 nm) epitaxial layers of Yttrium Iron Garnet Y{sub 3}Fe{sub 5}O{sub 12} (YIG) on (111)–oriented Gadolinium Gallium Garnet substrates at different growth conditions. Atomic force microscopy showed flat surface morphology both on micrometer and nanometer scales. X-ray diffraction measurements revealed that the films are coherent with the substrate in the interface plane. The interplane distance in the [111] direction was found to be by 1.2% larger than expected for YIG stoichiometric pseudomorphic film indicating presence of rhombohedral distortion in this direction. Polar Kerr effect and ferromagnetic resonance measurements showed existence of additional magnetic anisotropy, which adds to the demagnetizing field to keep magnetization vector in the film plane. The origin of the magnetic anisotropy is related to the strain in YIG films observed by XRD. Magneto-optical Kerr effect measurements revealed important role of magnetization rotation during magnetization reversal. An unusual fine structure of microwave magnetic resonance spectra has been observed in the film grown at reduced (0.5 mTorr) oxygen pressure. Surface spin wave propagation has been demonstrated in the in-plane magnetized films.

  17. Clinical Applications of Gallium-68

    Science.gov (United States)

    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

  18. Clinical applications of Gallium-68.

    Science.gov (United States)

    Banerjee, Sangeeta Ray; Pomper, Martin G

    2013-06-01

    Gallium-68 is a positron-emitting radioisotope that is produced from a (68)Ge/(68)Ga 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. (68)Ga-DOTATOC, (8)Ga-DOTATATE, (68)Ga-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 (68)Ga 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 (68)Ga-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 (68)Ga-labeled imaging agents used in nuclear medicine. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Garnet peridotites from Pohorje: Petrography, geothermobarometry and metamorphic evolution

    Directory of Open Access Journals (Sweden)

    Mirijam Vrabec

    2010-06-01

    Full Text Available Ultrahigh-pressure (UHP metamorphism has been recorded in Eo-Alpine garnet peridotites from the PohorjeMts., Slovenia, belonging to the Eastern Alps. The garnet peridotite bodies are found within serpentinized metaultrabasitesin the SE edge of Pohorje and are closely associated with UHP kyanite eclogites. These rocks belongto the Lower Central Austroalpine basement unit of the Eastern Alps, exposed in the proximity of the Periadriaticfault system.Garnet peridotites show signs of a complex four-stage metamorphic history. The protolith stage is represented bya low-P high-T assemblage of olivine + Al-rich orthopyroxene + Al-rich clinopyroxene + Cr-spinel. Due to metamorphism,primary clinopyroxene shows exsolutions of garnet, orthopyroxene, amphibole, Cr-spinel and ilmenite. TheUHP metamorphic stage is defined by the assemblage garnet + olivine + Al-poor orthopyroxene + clinopyroxene +Cr-spinel. Subsequent decompression and final retrogression stage resulted in formation of kelyphitic rims aroundgarnet and crystallization of tremolite, chlorite, serpentine and talc.Pressure and temperature estimates indicate that garnet peridotites reached the peak of metamorphism at 4 GPaand 900 °C, that is well within the UHP stability field. Garnet peridotites in the Pohorje Mountains experiencedUHP metamorphism during the Cretaceous orogeny and thus record the highest-pressure conditions of all Eo-Alpinemetamorphism in the Alps.

  20. Glutathione role in gallium induced toxicity

    African Journals Online (AJOL)

    Asim

    2012-01-26

    GSH) present in tissues. It is very important and interesting to study the reaction of gallium nitrate and glutathione as biomarker of glutathione role in detoxification and conjugation in whole blood components (plasma and ...

  1. Scandium-doped zinc cadmium oxide as a new stable n-type oxide thermoelectric material

    DEFF Research Database (Denmark)

    Han, Li; Christensen, Dennis Valbjørn; Bhowmik, Arghya

    2016-01-01

    Scandium-doped zinc cadmium oxide (Sc-doped ZnCdO) is proposed as a new n-type oxide thermoelectric material. The material is sintered in air to maintain the oxygen stoichiometry and avoid instability issues. The successful alloying of CdO with ZnO at a molar ratio of 1 : 9 significantly reduced...... is a good candidate for improving the overall conversion efficiencies in oxide thermoelectric modules. Meanwhile, Sc-doped ZnCdO is robust in air at high temperatures, whereas other n-type materials, such as Al-doped ZnO, will experience rapid degradation of their electrical conductivity and ZT....

  2. Gallium beam lithography for superconductive structure formation

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Michael David; Lewis, Rupert M.

    2018-01-30

    The present invention relates to the use of gallium beam lithography to form superconductive structures. Generally, the method includes exposing a surface to gallium to form an implanted region and then removing material adjacent to and/or below that implanted region. In particular embodiments, the methods herein provide microstructures and nanostructures in any useful substrate, such as those including niobium, tantalum, tungsten, or titanium.

  3. Gallium poisoning: a rare case report.

    Science.gov (United States)

    Ivanoff, Chris S; Ivanoff, Athena E; Hottel, Timothy L

    2012-02-01

    The authors present a case of a college student who suffered acute gallium poisoning as a result of accidental exposure to gallium halide complexes. This is extremely rare and has never been reported in the literature. Acute symptoms after the incident, which initially presented as dermatitis and appeared relatively not life-threatening, rapidly progressed to dangerous episodes of tachycardia, tremors, dyspnea, vertigo, and unexpected black-outs. Had there been effective emergency medical care protocols, diagnostic testing, treatment and antidotes, the latent manifestations of irreversible cardiomyopathy may have been prevented. Given how quickly exposure led to morbidity, this article aims to raise an awareness of the toxic potential of gallium. This has particular relevance for workers involved in the production of semiconductors where there is a potential for accidental exposure to gallium by-products during device processing. It may also have implications for dentists who use gallium alloys to replace mercury containing amalgam. In the absence of threshold limit values and exposure limits for humans, as well as emergency medical guidelines for treatment of poisoning, the case calls on the National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration to establish guidelines and medical management protocols specific for gallium. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Garnet--An Essential Industrial Mineral and January's Birthstone

    Science.gov (United States)

    Evans, James G.; Moyle, Phillip R.; Frank, David G.; Olson, Donald W.

    2006-01-01

    Garnet is one of the most common minerals in the world. Occurring in almost any color, it is most widely known for its beauty as a gem stone. Because of its hardness and other properties, garnet is also an essential industrial mineral used in abrasive products, non-slip surfaces, and filtration. To help manage our Nation's resources of such essential minerals, the U.S. Geological Survey (USGS) provides crucial data and scientific information to industry, policymakers, and the public.

  5. Garnets from the Camafuca-Camazambo kimberlite (Angola

    Directory of Open Access Journals (Sweden)

    Correia Eugénio A.

    2006-01-01

    Full Text Available This work presents a geochemical study of a set of garnets, selected by their colors, from the Camafuca-Camazambo kimberlite, located on northeast Angola. Mantle-derived garnets were classified according to the scheme proposed by Grütter et al. (2004 and belong to the G1, G4, G9 and G10 groups. Both sub-calcic (G10 and Ca-saturated (G9 garnets, typical, respectively, of harzburgites and lherzolites, were identified. The solubility limit of knorringite molecule in G10D garnets suggests they have crystallized at a minimum pressure of about 40 to 45 kbar (4-4.5 GPa. The occurrence of diamond stability field garnets (G10D is a clear indicator of the potential of this kimberlite for diamond. The chemistry of the garnets suggests that the source for the kimberlite was a lherzolite that has suffered a partial melting that formed basaltic magma, leaving a harzburgite as a residue.

  6. Scandium and yttrium phosphasalen complexes as initiators for ring-opening polymerization of cyclic esters.

    Science.gov (United States)

    Bakewell, Clare; White, Andrew J P; Long, Nicholas J; Williams, Charlotte K

    2015-03-02

    The synthesis and characterization of novel scandium and yttrium phosphasalen complexes is reported, where phosphasalen refers to two different bis(iminophosphorane) derivatives of the more ubiquitous salen ligands. The activity of the complexes as initiators for the ring-opening polymerization of cyclic esters is presented. The scandium complexes are inactive for lactide polymerization but slow and controlled initiators for ε-caprolactone polymerization. The lack of activity toward lactide exhibited by these compounds is probed, and a rare example of single-monomer insertion product, unable to undergo further reactions with lactide, is identified. In contrast, the analogous yttrium phosphasalen complex is a very active initiator for the ring-opening polymerization of rac-lactide (kobs = 1.5 × 10(-3) s(-1) at 1:500 [yttrium initiator]:[rac-lactide], 1 M overall concentration of lactide in THF at 298 K). In addition to being a very fast initiator, the yttrium complex also maintains excellent levels of polymerization control and a high degree of isoselectivity, with the probability of isotactic enchainment being Pi = 0.78 at 298 K.

  7. Thermodynamic parameters of scandium trifluoride and triiodide in the condensed state

    Science.gov (United States)

    Aristova, N. M.; Belov, G. V.

    2015-06-01

    The thermodynamic properties of new classes of compounds, particularly scandium trihalides ScF3, ScCl3, ScBr3, and ScI3, are added to the IVTANTHERMO software package. A critical analysis and processing of the entire array of primary data available in the literature is performed. An equation approximating the temperature dependence of heat capacity in the temperature range 298.15- T m (K) is derived for each crystalline scandium trihalide. The resulting equations C {/p po}( T) for the solid state and the data for the liquid phase are used to calculate the thermodynamic functions of entropy, the reduced Gibbs free energies, and the enthalpy increments. Both the experimental data available in literature and the missing estimated thermodynamic data are used in calculations. The error of the recommended values is estimated in all cases. In the first part of this work, we describe the thermodynamic properties of ScF3 and ScI3 used as the reference data for calculating the thermodynamic functions of ScCl3 and ScBr3, for which experimental data are either very scarce or missing altogether. The resulting data are added to the database of the IVTANTHERMO software package.

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

    Science.gov (United States)

    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.

  9. Speed gallium arsenide photoconductors; Photoconducteurs rapides en arseniure de gallium

    Energy Technology Data Exchange (ETDEWEB)

    Foulon, F.; Pochet, T. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Electronique et d`Instrumentation Nucleaire; Brullot, B. [CEA Centre d`Etudes de Bruyeres-le-Chatel, 91 (France)

    1993-12-31

    Gallium arsenide detectors are one of the most efficient gamma and X ray detectors at room temperature. Due to the high carrier mobility and short carrier lifetime, GaAs can be used for the detection of ultrafast gamma, X or laser pulses. GaAs photoconductors allow both pulse shape and intensity measurements. In this paper, we review the results of studies carried out jointly by the CEA/LETI/DEIN and CEA/DAM/CEM in France to improve the response of such detectors. The geometry of the photodetectors and their electrical contacts have been optimized for specific radiation measurements: low energy X rays (< 1 KeV), gamma rays or protons. It has been shown that a pre-irradiation treatment with fission neutrons at doses above 10{sup 14} n/cm{sup 2} induces a significant improvement of the response speed. This result from defect generation in the material and the subsequent carrier life time decrease. Detectors with sensitivities of about 10{sup -8} A/R.s for gamma rays and 10{sup -16} coulomb/proton, response times below 100 ps and good linearity over more than five decades are currently fabricated in our laboratory. (authors). 18 refs., 5 figs., 3 tabs.

  10. Presumed Multiple Metasomatism underneath the Colorado Plateau; Decoding from Chemistry and Inclusion/Lamella Mineralogy of Diverse Garnets from the Garnet Ridge, Northern Arizona

    Science.gov (United States)

    Sato, Y.; Ogasawara, Y.

    2015-12-01

    Various garnets containing the information on mantle petrology and related metasomatism occur at the Garnet Ridge, Colorado Plateau. The origins of garnets range from deep mantle to shallow continental crust. These garnets were delivered by kimberlitic diatreme of 30 Ma (Smith et al. 2004). We have classified the garnets into 10 groups (A to J, see figure) by naked eye observation, major chemistry, minor Na-Ti-P, inclusion/lamella mineralogy. Among them, groups A to D are of mantle origin, E to G of subducted oceanic crust origin, and H to J of continental crust origin. We summarized results as in the followings. A: Cr and pyrope-rich garnet has Cr2O3(0.8-6.3 wt.%) and inclusions of Ol, Cpx, Opx, Ti-Chu/Chn and carbonates, indicating carbonated garnet lherzolites as host. Cr contents negatively correlates with Na-Ti-P contents and occurrence of exsolved Rt, Ilm and crichtonite. This indicates Cr-rich end-member is the most "primitive" mantle garnet before metasomatism. B: Pyrope-rich reddish brown garnet of peridotitic origins was subdivided into 4 subgroups (B1 to B4, see figure). Compositional range in Ca-Mg-Fe triangle expands to Fe-rich side from group A. Exsolved Na-bearing amphibole and inclusions of Ap, carbonates and fluid were identified. These indicate metasomatism of group A. C: Garnet megacryst is coarse-grained garnet (2-10 cm across) with crystal faces. This garnet has wide chemical variation plotted in the center area of Ca-Mg-Fe triangle. D: Garnet aggregate has similar chemistry of group C and is composed of several grains. Grain boundaries of garnet were recognized by Rt, Ilm and other minerals and oscillatory zonings of Ca, Mg, Fe and Na-Ti-P. Fluid inclusions of groups C and D suggest these garnets might crystalized from fluid. E: Garnet in eclogite and F: Garnet in metasomatized eclogite are xenolith samples (the Fallaron Plate origin?). Aggregate of Zo+Ab contained in group E indicates decomposed precursor lawsonite inclusion. G: Quartz

  11. Correction: Ambient temperature deposition of gallium nitride/gallium oxynitride from a deep eutectic electrolyte, under potential control.

    Science.gov (United States)

    Sarkar, Sujoy; Sampath, S

    2016-05-28

    Correction for 'Ambient temperature deposition of gallium nitride/gallium oxynitride from a deep eutectic electrolyte, under potential control' by Sujoy Sarkar et al., Chem. Commun., 2016, 52, 6407-6410.

  12. Development of a Multi-layer Anti-reflective Coating for Gallium Arsenide/Aluminum Gallium Arsenide Solar Cells

    Science.gov (United States)

    2015-07-01

    Aluminum Gallium Arsenide Solar Cells by Kimberley A Olver Approved for public release; distribution unlimited...Development of a Multi-layer Anti-reflective Coating for Gallium Arsenide/Aluminum Gallium Arsenide Solar Cells by Kimberley A Olver...Aluminum Gallium Arsenide (AlGaAs) Solar Cells 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Kimberley A Olver

  13. Dating Subduction Zone Metamorphism with Garnet and Lawsonite Geochronology

    Science.gov (United States)

    Mulcahy, S. R.; Vervoort, J. D.

    2013-12-01

    Lawsonite [CaAl2Si2O7(OH)2 H2O] is a critical index mineral for high- to ultrahigh-pressure metamorphism associated with subduction. Lawsonite is an important carrier of water into the mantle, a likely contributor to subduction zone seismicity, and a bearer of trace elements that link metamorphism to arc magmatism. Due to its limited pressure-temperature stability, lawsonite can serve as a powerful petrogenetic indicator of specific metamorphic events. Lu-Hf dating of lawsonite, therefore provides a potentially powerful new tool for constraining subduction zone processes in a pressure-temperature window where few successful geochronometers exist. Broad application of lawsonite Lu-Hf geochronology requires constraining the role of pressure-temperature path, lawsonite forming reactions, and the Lu and Hf systematics within lawsonite and other blueschist facies minerals. We are working to address the role of the metamorphic path on the applicability of lawsonite Lu-Hf geochronology within the Franciscan Complex of California. The Franciscan Complex preserves mafic high-grade exotic blocks in melange that underwent a counterclockwise pressure-temperature path wherein garnet, which strongly partitions heavy rare-earth elements, formed prior to lawsonite. Coherent mafic rocks within the Franciscan Complex, however, underwent a clockwise pressure-temperature path and lawsonite growth occurred prior to garnet. We sampled exotic blocks of garnet-hornblendite, garnet-epidote amphibolite, garnet-epidote blueschist, and lawsonite blueschist from the Berkeley Hills and Tiburon Peninsula of California. We collected four samples from coherent lawsonite blueschist across the lawsonite-pumpellyite-epidote isograds in Ward Creek, near Cazadero California. High-grade blocks give ages similar to existing Franciscan geochronology: multi-stage garnet in hornblendite gives the following ages: 171×1.3 Ma (MSWD 2.8) for the core and 159.4×0.9 Ma (MSWD 2.0) for the corresponding rim; 166

  14. Ambient temperature deposition of gallium nitride/gallium oxynitride from a deep eutectic electrolyte, under potential control.

    Science.gov (United States)

    Sarkar, Sujoy; Sampath, S

    2016-05-11

    A ternary, ionically conducting, deep eutectic solvent based on acetamide, urea and gallium nitrate is reported for the electrodeposition of gallium nitride/gallium indium nitride under ambient conditions; blue and white light emitting photoluminescent deposits are obtained under potential control.

  15. Capacitive Behavior of Single Gallium Oxide Nanobelt.

    Science.gov (United States)

    Cai, Haitao; Liu, Hang; Zhu, Huichao; Shao, Pai; Hou, Changmin

    2015-08-17

    In this research, monocrystalline gallium oxide (Ga₂O₃) nanobelts were synthesized through oxidation of metal gallium at high temperature. An electronic device, based on an individual Ga₂O₃ nanobelt on Pt interdigital electrodes (IDEs), was fabricated to investigate the electrical characteristics of the Ga2O3 nanobelt in a dry atmosphere at room temperature. The current-voltage (I-V) and I/V-t characteristics show the capacitive behavior of the Ga₂O₃ nanobelt, indicating the existence of capacitive elements in the Pt/Ga₂O₃/Pt structure.

  16. Recovery of Scandium(III) from Aqueous Solutions by Solvent Extraction with the Functionalized Ionic Liquid Betainium Bis(trifluoromethylsulfonyl)imide

    OpenAIRE

    Onghena, Bieke; Binnemans, Koen

    2015-01-01

    The ionic liquid betainium is(trifluoromethylsulfonyl)imide [Hbet][Tf2N] was used for the extraction of scandium from aqueous solutions. The influence of several extraction parameters on the extraction efficiency was investigated, including the initial metal concentration, phase ratio, and pH. The extraction kinetics was examined, and a comparison was made between conventional liquid−liquid extraction and homogeneous liquid−liquid extraction (HLLE). The stoichiometry of the extracted scandium...

  17. Four Terminal Gallium Nitride MOSFETs

    Science.gov (United States)

    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

  18. Browse Title Index

    African Journals Online (AJOL)

    Items 501 - 550 of 1605 ... Vol 18, No 4 (2015), Effects of edentulism in obstructive sleep apnea syndrome, Abstract PDF. R Okşayan, O Sökücü, M Uyar, T Topçuoğlu. Vol 18, No 2 (2015), Effects of erbium‑and chromium‑doped yttrium scandium gallium garnet and diode lasers on the surfaces of restorative dental materials: A ...

  19. Treatment of oral submucous fibrosis with ErCr: YSGG laser

    Directory of Open Access Journals (Sweden)

    Zainab Chaudhary

    2011-01-01

    Full Text Available Oral submucous fibrosis (OSMF is one of the most poorly understood and unsatisfactorily treated diseases. Various medical and surgical treatments have been used but with limited benefits. However, with advent of lasers, oral surgeons are provided with new modality for treating OSMF. This case report highlights the pioneering effort in treating a moderate case of bilateral OSMF with Erbium Chromium Yttrium Scandium Gallium Garnet (ErCr:YSGG laser showing promising result during follow-up.

  20. Organization of the Topical Meeting on Tunable Solid State Lasers Held in North Falmouth, Massachusetts on 1-3 May 1989

    Science.gov (United States)

    1989-08-30

    section can be compared to the cross-section obtained for Cr(III) in gallium scandium gadolinium garnet (GSGG) at 756 nm, which is 0.7 Pm 2 [12], and for...p. 34) ME1 Laser Performance of Chromium- Aluminum Doped Forsterite, Horacio R. Verdun, Leonard M. Thomas, Donna M. 11:30 AM (Invited Paper...Chromium- aluminum gaussian Mirrors, G. Cerullo, V. Magni, R. Riva, 0. Svelto, doped forsterite, prepared by laser-heated pedestal growth, Polytechnic U

  1. Modification mechanism of eutectic silicon in Al–6Si–0.3Mg alloy with scandium

    Energy Technology Data Exchange (ETDEWEB)

    Patakham, Ussadawut [Manufacturing and Systems Engineering Program, Department of Production Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand); Kajornchaiyakul, Julathep [National Metal and Material Technology Center, National Science and Technology Development Agency, 114 Thailand Science Park, Klong Nueng, Klong Luang, Pathumthani 12120 (Thailand); Limmaneevichitr, Chaowalit, E-mail: chaowalit.lim@kmutt.ac.th [Manufacturing and Systems Engineering Program, Department of Production Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand)

    2013-10-25

    Highlights: •Morphologies and growth of Sc and Sr-modified eutectic silicon resemble those of dendrites. •Crystal orientation of eutectic aluminum depends on growth characteristics of eutectic silicon. •We report strong evidence of the occurrence of an impurity-induced twinning mechanism. -- Abstract: The modification mechanism of eutectic silicon in Al–6Si–0.3Mg alloy with scandium was studied. The crystallographic orientation relationships between primary dendrites and the eutectic phase of unmodified and modified Al–6Si–0.3 Mg alloys were determined using electron backscatter diffraction (EBSD). The orientation of aluminum modified with scandium in the eutectic phase was different from that of the neighboring primary dendrites. This result implies that eutectic aluminum grows epitaxially from the surrounding primary aluminum dendrites in the unmodified alloy and that eutectic aluminum grows competitively from the surrounding primary aluminum dendrites in the modified alloy. The pole figure maps of eutectic Si in the [1 0 0], [1 1 0] and [1 1 1] axes of the unmodified and Sc-modified alloys were different, suggesting that the eutectic Al and Si crystals in modified alloy growth are more isotropic and cover a larger set of directions. The lattice fringes of Si of the alloys with and without Sc modification were different in the TEM results. The lattice fringes of Si in modified alloy were found to be multiple twins. However, this was not observed in the unmodified alloy. The growth characteristic of eutectic Si crystal in modified alloy suggests the occurrence of multiple twinning reactions and the formation of a high density of twins. This modification mechanism by Sc is explained by the results of scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analysis, which provide strong evidence of the occurrence of the impurity-induced twinning (IIT) mechanism.

  2. Grain refinement mechanism in an Al-Si-Mg alloy with scandium

    Energy Technology Data Exchange (ETDEWEB)

    Patakham, Ussadawut [Department of Production Engineering, Faculty of Engineering, King Mongkut' s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand); Kajornchaiyakul, Julathep [National Metal and Material Technology Center, National Science and Technology Development Agency, 114 Thailand Science Park, Klong Nueng, Klong Luang, Pathumthani 12120 (Thailand); Limmaneevichitr, Chaowalit, E-mail: chaowalit.lim@kmutt.ac.th [Department of Production Engineering, Faculty of Engineering, King Mongkut' s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand)

    2012-11-25

    Highlights: Black-Right-Pointing-Pointer Scandium can be used to refine aluminum grains in an Al-Si-Mg aluminum alloy. Black-Right-Pointing-Pointer The effectiveness of Sc is lower than that of conventional Al-Ti grain refiners. Black-Right-Pointing-Pointer Al{sub 3}Sc particles can act as heterogeneous nuclei of aluminum phases. Black-Right-Pointing-Pointer Higher alloying elements cause more intermetallic compound phases. Black-Right-Pointing-Pointer Those phases cannot effectively act as heterogeneous nuclei compared with Al{sub 3}Sc particles. - Abstract: Grain refinement of the primary aluminum ({alpha}-Al) phase in a hypoeutectic Al-Si alloy using scandium (Sc) was studied to identify the grain refinement mechanism. Optical microscopy (OM), Scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) techniques were extensively used in this study. We found that Sc refined grains of primary aluminum. However, the grain refinement efficiency of Sc was considerably lower than that of titanium (Ti) in the Al-Si-Mg foundry alloy. It was evident that the precipitated Sc-containing phases acted as heterogeneous nucleation sites for the primary aluminum phase. The Sc-containing heterogeneous sites are irregular in shape with sizes between 3 and 5 {mu}m. At least three groups of nuclei based on their chemical composition were found, i.e., (i) Al and Sc, (ii) Al, Si, Mg, and Sc, and (iii) Al, Si, Mg, Sc, and Fe. Crystal orientation mapping showed primary aluminum dendrites with one orientation in each grain near Al{sub 3}Sc particles. The grain refinement mechanism of Sc for aluminum relies on heterogeneous nucleation of Al{sub 3}Sc particles, with less responsibly for grain growth restriction. Many intermetallic phases with Al, Si, Fe, Mg and Sc as their major components were found, and these phases could not effectively act as heterogeneous nuclei.

  3. Two-Dimensional Modeling of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistor

    National Research Council Canada - National Science Library

    Holmes, Kenneth

    2002-01-01

    Gallium Nitride (GaN) High Electron Mobility Transistors (HEMT's) are microwave power devices that have the performance characteristics to improve the capabilities of current and future Navy radar and communication systems...

  4. Amphiboles from the garnet glaucophane schists in the Bizan area, Sambagawa metamorphic belt, eastern Shikoku, Japan

    OpenAIRE

    Kabir, Md. Fazle; Takasu, Akira

    2015-01-01

    The Sambagawa metamorphic belt in the Bizan area consists mainly of pelitic schists, basic schists, and siliceous schists, along with minor garnet glaucophane schists. Garnet glaucophane schists consist mainly of garnet and amphibole (glaucophane, ferroglaucophane, barroisite, katophorite and taramite), with minor amounts of epidote, phengite, paragonite, chlorite, albite, titanite, and quartz. Clinopyroxene (jadeite-omphacite), chloritoid, rutile, ilmenite, calcite, K-feldspar, zircon occur ...

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

    Science.gov (United States)

    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 μg/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

  6. Anisotropy of the magnetic susceptibility of gallium

    Science.gov (United States)

    Pankey, T.

    1960-01-01

    The bulk magnetic susceptibilities of single gallium crystals and polycrystalline gallium spheres were measured at 25??C. The following anisotropic diamagnetic susceptibilities were found: a axis (-0.119??0. 001)??10-6 emu/g, b axis (-0.416??0.002)??10 -6 emu/g, and c axis (-0.229??0.001) emu/g. The susceptibility of the polycrystalline spheres, assumed to be the average value for the bulk susceptibility of gallium, was (-0.257??0.003)??10-6 emu/g at 25??C, and (-0.299??0.003)??10-6 emu/g at -196??C. The susceptibility of liquid gallium was (0.0031??0.001) ??10-6 emu/g at 30??C and 100??C. Rotational diagrams of the susceptibilities in the three orthogonal planes of the unit cell were not sinusoidal. The anisotropy in the single crystals was presumably caused by the partial overlap of Brillouin zone boundaries by the Fermi-energy surface. The large change in susceptibility associated with the change in state was attributed to the absence of effective mass influence in the liquid state. ?? 1960 The American Institute of Physics.

  7. Gallium-67 imaging in pulmonary eosinophilic granuloma

    Energy Technology Data Exchange (ETDEWEB)

    Makhija, M.C.; Davis, G.

    1984-03-01

    Gallium-67 citrate has been known to localize in the lungs in a variety of pulmonary diseases. Abnormal lung activity implies active underlying disease. Serial Ga-67 lung scans may be helpful when steroids are used as therapeutic agents. A case of pulmonary eosinophic granuloma is reported here with diffuse bilateral Ga-67 pulmonary activity.

  8. Gallium nitride junction field-effect transistor

    Science.gov (United States)

    Zolper, John C.; Shul, Randy J.

    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.

  9. Gallium Electromagnetic (GEM) Thruster Performance Measurements

    Science.gov (United States)

    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.

  10. Thermodynamic binding constants for gallium transferrin

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Treatment of amalgam tattoo with an Er,Cr:YSGG laser.

    Science.gov (United States)

    Yilmaz, Hasan Guney; Bayindir, Hakan; Kusakci-Seker, Basak; Tasar, Simge; Kurtulmus-Yilmaz, Sevcan

    2010-08-01

    Amalgam tattoos are common, asymptomatic, pigmented oral lesions that clinically exist as isolated, blue, gray, or black macules on the gingival, buccal, and alveolar mucosae, the palate, and/or the tongue. In this case report, the successful use of an erbium, chromium-doped:yttrium, scandium, gallium, and garnet laser for the removal of an amalgam tattoo is explained. A 46-year-old man is presented with a half decade history of an amalgam tattoo on his left maxillary premolar-molar gingiva. Depigmentation procedure was performed under topical anesthesia with the use of an erbium, chromium-doped:yttrium, scandium, gallium, and garnet laser at 2 W in the soft tissue pulsed mode for 10 min. The pigmented tissue was completely removed. The de-epithelialization area healed completely on the 10th day after treatment. The period of healing was uneventful. The amalgam tattoo was completely removed with erbium, chromium-doped:yttrium, scandium, gallium, and garnet laser, and the treated area healed without any adverse effect. © 2010 Blackwell Publishing Asia Pty Ltd.

  12. Gallium 67 scintigraphy in glomerular disease

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. The Use of Chemistry of Garnets and Heavy Minerals Around ...

    African Journals Online (AJOL)

    ... to the conclusion of having a barren kimberlite source. It is suggested that combination of the chemistry of garnet and heavy minerals may be used as an exploration tool for deciphering diamond and non-diamond bearing kimberlites. Keywords: Electron microprobe, black minerals, mineral and fluid inclusions, kimberlites, ...

  14. Static Magnetic Properties of AL800 Garnet Material

    Energy Technology Data Exchange (ETDEWEB)

    Kuharik, J. [Fermilab; Madrak, R. [Fermilab; Makarov, A. [Fermilab; Pellico, W. [Fermilab; Sun, S. [Fermilab; Tan, C. Y. [Fermilab; Terechkine, I. [Fermilab

    2017-05-17

    A second harmonic tunable RF cavity is being devel-oped for the Fermilab Booster. This device, which prom-ises reduction of the particle beam loss at the injection, transition, and extraction stages, employs perpendicularly biased garnet material for frequency tuning. The required range of the tuning is significantly wider than in previously built and tested tunable RF devices. As a result, the mag-netic field in the garnet comes fairly close to the gyromag-netic resonance line at the lower end of the frequency range. The chosen design concept of a tuner for the cavity cannot ensure uniform magnetic field in the garnet mate-rial; thus, it is important to know the static magnetic prop-erties of the material to avoid significant increase in the lo-cal RF loss power density. This report summarizes studies performed at Fermilab to understand variations in the mag-netic properties of the AL800 garnet material used to build the tuner of the cavity.

  15. On fabrication procedures of Li-ion conducting garnets

    Energy Technology Data Exchange (ETDEWEB)

    Hanc, Emil [The Mineral and Energy Economy Research Institute, Polish Academy of Sciences, ul. Wybickiego 7, 31-261 Kraków (Poland); Zając, Wojciech, E-mail: wojciech.zajac@agh.edu.pl [AGH University of Science and Technology, Faculty of Energy and Fuels, al. Mickiewicza 30, 30-059 Kraków (Poland); Lu, Li; Yan, Binggong; Kotobuki, Masashi [Materials Science Group, Department of Mechanical Engineering, National University of Singapore (Singapore); Ziąbka, Magdalena [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, al. Mickiewicza 30, 30-059 Kraków (Poland); Molenda, Janina [AGH University of Science and Technology, Faculty of Energy and Fuels, al. Mickiewicza 30, 30-059 Kraków (Poland)

    2017-04-15

    Ceramic oxides exhibiting high lithium-ion mobility at room temperature receive broad attention as candidate electrolytes for lithium batteries. Lithium-stuffed garnets from the Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} group seem to be especially promising because of their high ionic conductivity at room temperature and their electrochemical stability. In this work, we discuss factors that affect formation of the garnet in its bulk form or in the form of thick and thin films. We demonstrate that zinc oxide can be applied as a sintering aid that facilitate the formation of the highly conducting cubic Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} garnet phase in a single-step sintering procedure. Based on our experience with the single-step sintering experiments, we successfully fabricated a thick-film membrane consisting of a garnet solid electrolyte using the tape casting technique. In order to reduce the thickness of the electrolyte even further we investigated the fabrication of a thin-film Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} electrolyte by means of the pulsed laser deposition technique.

  16. Polyphase deformation and garnet growth in politic schists of Sausar ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 116; Issue 5. Polyphase deformation and garnet growth in politic schists of Sausar Group in Ramtek area, Maharashtra, India: A study of porphyroblast–matrix relationship. A Chattopadhyay N Ghosh. Volume 116 Issue 5 October 2007 pp 423-432 ...

  17. Polyphase deformation and garnet growth in pelitic schists of Sausar ...

    Indian Academy of Sciences (India)

    Polyphase deformation and metamorphism of pelitic schists of Chorbaoli Formation of Sausar. Group in and around Ramtek area, Nagpur district, Maharashtra, India has led to the development of garnet and staurolite porphyroblasts in a predominantly quartz–mica matrix. Microstructural study of oriented thin sections of ...

  18. Systematic hardness measurements on some rare earth garnet ...

    Indian Academy of Sciences (India)

    Unknown

    microwave and magnetic bubble devices. When doped with Nd, some of the rare earth garnets act as excellent laser hosts. Their photoemission spectra are ..... Grants Commission, New Delhi, for financial support by way of an emeritus fellowship. References. Chin G Y 1975a Deformation of ceramic materials (New York:.

  19. Neutron and Charged-Particle Induced Cross Sections for Radiochemistry for Isotopes of Scandium, Titanium, Vanadium, Chromium, Manganese, and Iron

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, K; Hoffman, R D; Dietrich, F S; Bauer, R; Mustafa, M

    2004-11-30

    We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Local systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron and proton induced nuclear reaction cross sections in the mass region of scandium, titanium, vanadium, chromium, manganese, and iron (21 {le} Z {le} 26, 20 {le} N {le} 32).

  20. A composite cathode based on scandium doped titanate with enhanced electrocatalytic activity towards direct carbon dioxide electrolysis.

    Science.gov (United States)

    Yang, Liming; Xie, Kui; Wu, Lan; Qin, Qingqing; Zhang, Jun; Zhang, Yong; Xie, Ting; Wu, Yucheng

    2014-10-21

    A composite cathode based on redox-stable La0.2Sr0.8TiO(3+δ) (LSTO) can perform direct carbon dioxide electrolysis; however, the insufficient electro-catalytic activity limits the electrode performances and current efficiencies. In this work, catalytically active scandium is doped into LSTO to enhance the electro-catalytic activity for CO2 electrolysis. The structures, electronic conductivities and ionic conductivities of La0.2Sr0.8Ti(1-x)Sc(x)O (LSTS(x)O) (x = 0, 0.05, 0.1, 0.15 and 0.2) are systematically studied and further correlated with electrode performances. The ionic conductivities of single-phase LSTS(x)O (x = 0, 0.05, 0.1 and 0.15) remarkably improve versus the scandium doping contents though the electrical conductivities gradually change in an adverse trend. Electrochemical measurements demonstrate promising electrode polarisation of LSTS(x)O electrodes and increasing scandium doping contents accordingly improve electrode performances. The Faradic efficiencies of carbon dioxide electrolysis are enhanced by 20% with LSTS0.15O in contrast to bare LSTO electrodes in a solid oxide electrolyser at 800 °C.

  1. Combined external-beam PIXE and /μ-Raman characterisation of garnets used in Merovingian jewellery

    Science.gov (United States)

    Calligaro, T.; Colinart, S.; Poirot, J.-P.; Sudres, C.

    2002-04-01

    Red garnets were the dominant gemstones used for jewels in Europe during the Early Middle Ages. We have studied over 350 garnets set on 12 jewels unearthed in the royal necropolis of the Saint-Denis Basilica, close to Paris. This famous collection of "cloisonné" style artefacts dates from the Merovingian period (late fifth century AD to early seventh century AD). The archaeological issue addressed is the identification of the geographical origin of these garnets, in view to establish the gem trading routes during the Dark Ages. External beam PIXE was used to determine the major constituents (Mg, Al, Si, Ca, Mn, Fe), specifying the garnet type (composition in various mineralogical end-members, e.g. almandine, pyrope, spessartite, …), and the trace element content (Cr, Y). Three sorts of garnets were identified. Ten jewels are adorned with almandine garnets (Fe-rich). One jewel has intermediate almandine-pyrope garnets ("rhodolite"). The last and most recent jewel is inlaid with pyrope (Mg-rich) garnets. Trace element content and slight differences in major composition allowed to distinguish five different sources: two sources for pyrope garnets (with and without chromium), and two sources for almandine garnets (distinctive calcium, magnesium and yttrium contents). A preliminary comparison with literature data suggested that almandine garnets may have been mined from India while the "rhodolite" garnets may have been imported from Sri Lanka. The sources of pyrope garnets could be the Bohemian deposits (Czech republic). In addition, μ-Raman spectrometry was used to identify most of the mineral inclusions (apatite, zircon, ilmenite, monazite, calcite, quartz) present in almandine garnets. Even if two specific types of inclusions were not identified, due to the lack of corresponding reference spectra in our database, the Raman spectra collected provided an interesting inclusion fingerprint.

  2. Combined external-beam PIXE and {mu}-Raman characterisation of garnets used in Merovingian jewellery

    Energy Technology Data Exchange (ETDEWEB)

    Calligaro, T. E-mail: thomas.calligaro@culture.gouv.fr; Colinart, S.; Poirot, J.-P.; Sudres, C

    2002-04-01

    Red garnets were the dominant gemstones used for jewels in Europe during the Early Middle Ages. We have studied over 350 garnets set on 12 jewels unearthed in the royal necropolis of the Saint-Denis Basilica, close to Paris. This famous collection of 'cloisonne' style artefacts dates from the Merovingian period (late fifth century AD to early seventh century AD). The archaeological issue addressed is the identification of the geographical origin of these garnets, in view to establish the gem trading routes during the Dark Ages. External beam PIXE was used to determine the major constituents (Mg, Al, Si, Ca, Mn, Fe), specifying the garnet type (composition in various mineralogical end-members, e.g. almandine, pyrope, spessartite, ...), and the trace element content (Cr, Y). Three sorts of garnets were identified. Ten jewels are adorned with almandine garnets (Fe-rich). One jewel has intermediate almandine-pyrope garnets ('rhodolite'). The last and most recent jewel is inlaid with pyrope (Mg-rich) garnets. Trace element content and slight differences in major composition allowed to distinguish five different sources: two sources for pyrope garnets (with and without chromium), and two sources for almandine garnets (distinctive calcium, magnesium and yttrium contents). A preliminary comparison with literature data suggested that almandine garnets may have been mined from India while the 'rhodolite' garnets may have been imported from Sri Lanka. The sources of pyrope garnets could be the Bohemian deposits (Czech republic). In addition, {mu}-Raman spectrometry was used to identify most of the mineral inclusions (apatite, zircon, ilmenite, monazite, calcite, quartz) present in almandine garnets. Even if two specific types of inclusions were not identified, due to the lack of corresponding reference spectra in our database, the Raman spectra collected provided an interesting inclusion fingerprint.

  3. Serum and tissue concentrations of gallium after oral administration of gallium nitrate and gallium maltolate to neonatal calves.

    Science.gov (United States)

    Monk, Caroline S; Sweeney, Raymond W; Bernstein, Lawrence R; Fecteau, Marie-Eve

    2016-02-01

    To determine serum and tissue concentrations of gallium (Ga) after oral administration of gallium nitrate (GaN) and gallium maltolate (GaM) to neonatal calves. 8 healthy neonatal calves. Calves were assigned to 1 of 2 groups (4 calves/group). Gallium (50 mg/kg) was administered as GaN or GaM (equivalent to 13.15 mg of Ga/kg for GaN and 7.85 mg of Ga/kg for GaM) by oral gavage once daily for 5 days. Blood samples were collected 0, 0.25, 0.5, 1, 2, 4, 8, 12, and 24 hours after Ga administration on day 1; 4 and 24 hours after Ga administration on days 2, 3, and 4; and 4, 12, and 24 hours after Ga administration on day 5. On day 6, calves were euthanized and tissue samples were obtained. Serum and tissue Ga concentrations were measured by use of mass spectrometry. Data were adjusted for total Ga dose, and comparisons were made between the 2 groups. Calves receiving GaM had a significantly higher dose-adjusted area under the curve and dose-adjusted maximum serum Ga concentration than did calves receiving GaN. Despite receiving less Ga per dose, calves receiving GaM had tissue Ga concentrations similar to those for calves receiving GaN. In this study, calves receiving GaM had significantly higher Ga absorption than did calves receiving GaN. These findings suggested that GaM might be useful as a prophylactic agent against Mycobacterium avium subsp paratuberculosis infection in neonatal calves.

  4. Survey of the market, supply and availability of gallium

    Energy Technology Data Exchange (ETDEWEB)

    Rosi, F.D.

    1980-07-01

    The objective of this study was to assess the present consumption and supply of gallium, its potential availability in the satellite power system (SPS) implementation time frame, and commercial and new processing methods for increasing the production of gallium. Findings are reported in detail. The findings strongly suggest that with proper long range planning adequate gallium would be available from free-enterprise world supplies of bauxite for SPS implementation.

  5. Gallium and its competing roles with iron in biological systems.

    Science.gov (United States)

    Chitambar, Christopher R

    2016-08-01

    Gallium, a group IIIa metal, shares chemical properties with iron. Studies have shown that gallium-based compounds have potential therapeutic activity against certain cancers and infectious microorganisms. By functioning as an iron mimetic, gallium perturbs iron-dependent proliferation processes in tumor cells. Gallium's action on iron homeostasis leads to disruption of ribonucleotide reductase, mitochondrial function, and the regulation of transferrin receptor and ferritin. In addition, gallium nitrate stimulates an increase in mitochondrial reactive oxygen species in cells which triggers downstream upregulation of metallothionein and hemoxygenase-1. Gallium's anti-infective activity against bacteria and fungi results from disruption of microbial iron utilization through mechanisms which include gallium binding to siderophores and downregulation of bacterial iron uptake. Gallium compounds lack cross-resistance to conventional chemotherapeutic drugs and antibiotics thus making them attractive agents for drug development. This review will focus on the mechanisms of action of gallium with emphasis on its interaction with iron and iron proteins. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Photonuclear Reaction Cross Sections for Gallium Isotopes

    CERN Document Server

    Akkoyun, Serkan

    2014-01-01

    The photon induced reactions which are named as photonuclear reactions have a great importance in many field of nuclear, radiation physics and related fields. Since we have planned to perform photonuclear reaction on gallium target with bremmstrahlung photons from clinical linear accelerator in the future, the cross-sections of neutron (photo-neutron ({\\gamma},xn)) and proton (photo-proton ({\\gamma},xn)) productions after photon activation have been calculated by using TALYS 1.2 computer code in this study. The target nucleus has been considered gallium which has two stable isotopes, 69Ga and 71Ga. According to the results, we have seen that the calculations are in harmony in the limited literature values. Furthermore, the pre-equilibrium and compound process contributions to the total cross-section have been investigated.

  7. Surface magnetism of gallium arsenide nanofilms

    OpenAIRE

    Lu, Huan; Yu, Jin; Guo, Wanlin

    2017-01-01

    Gallium arsenide (GaAs) is the widest used second generation semiconductor with a direct band gap and increasingly used as nanofilms. However, the magnetic properties of GaAs nanofilms have never been studied. Here we find by comprehensive density functional theory calculations that GaAs nanofilms cleaved along the and directions become intrinsically metallic films with strong surface magnetism and magnetoelectric (ME) effect. The surface magnetism and electrical conductivity are realized v...

  8. Gallium Nitride Crystals: Novel Supercapacitor Electrode Materials.

    Science.gov (United States)

    Wang, Shouzhi; Zhang, Lei; Sun, Changlong; Shao, Yongliang; Wu, Yongzhong; Lv, Jiaxin; Hao, Xiaopeng

    2016-05-01

    A type of single-crystal gallium nitride mesoporous membrane is fabricated and its supercapacitor properties are demonstrated for the first time. The supercapacitors exhibit high-rate capability, stable cycling life at high rates, and ultrahigh power density. This study may expand the range of crystals as high-performance electrode materials in the field of energy storage. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Unraveling the history of complex zoned garnets from the North Motagua Mélange (Guatemala)

    Science.gov (United States)

    Barickman, M. H.; Martin, C.; Flores, K. E.; Harlow, G. E.; Bonnet, G.

    2016-12-01

    The Guatemala Suture Zone (GSZ) is situated in central Guatemala, between the North American and Caribbean plates. Two serpentinite mélanges straddle the Motagua Fault system: the North Motagua Mélange (NMM) and the South Motagua Mélange (SMM). In this study, chemically zoned garnet grains from four eclogite blocks from the NMM were analyzed by EMPA for major elements and LA-ICP-MS for trace elements to unravel the geological history of the eclogites. These eclogites typically consist of euhedral to subhedral garnets, partly retrogressed omphacite grains, and accessory minerals such as phengite and epidote as inclusions in garnet. EBSD was employed to examine apparent garnet inclusions in garnet. The garnet grains in NMM eclogites display complex chemical zonations: all grains roughly show a spessartine-rich core, an almandine-rich core and/or intermediate zone, and a pyrope and grossular-rich rim. Additionally, crystal resorption can be observed between the different zones, and the pyrope-grossular rim can display oscillatory zoning. Finally, grossular-rich zones (crystallographically syntactic) within garnet are present in all studied samples. REE and spider diagrams do not show any significant difference in the patterns of the different zones within the garnet, or indicating that the chemical environment from which each garnet zone grew was broadly the same. The lack of significant variation in LILE content indicates that a fluid influx during garnet growth is unlikely. Consequently, we interpret that garnet grains grew in a largely closed system; however, the presence of the grossular-rich zones, argues for occasional excursions into conditions when either two garnets crystallized or Ca-rich overgrowths that were largely resorbed prior to subsequent continued garnet growth.

  10. Adsorption of hydrogen in Scandium/Titanium decorated nitrogen doped carbon nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Mananghaya, Michael, E-mail: mikemananghaya@gmail.com [De La Salle University, 2401 Taft Ave, 0922, Manila (Philippines); DLSU STC Laguna Boulevard, LTI Spine Road Barangays Biñan and Malamig, Biñan City, Laguna (Philippines); DOST-ASTHRDP, PCIEERD, Gen. Santos Ave., Bicutan, Taguig City 1631 (Philippines); Belo, Lawrence Phoa; Beltran, Arnel [De La Salle University, 2401 Taft Ave, 0922, Manila (Philippines); DLSU STC Laguna Boulevard, LTI Spine Road Barangays Biñan and Malamig, Biñan City, Laguna (Philippines)

    2016-09-01

    Nitrogen doped Carbon Nanotube with divacancy (4ND-CN{sub x}NT) that is decorated with Scandium and Titanium as potential hydrogen storage medium using the pseudo potential density functional method was investigated. Highly localized states near the Fermi level, which are derived from the nitrogen defects, contribute to strong Sc and Ti bindings, which prevent metal aggregation and improve the material stability. A detailed Comparison of the Hydrogen adsorption capability with promising system-weight efficiency of Sc over Ti was elucidated when functionalized with 4ND-CN{sub x}NT. Finally, the (Sc/4ND){sub 10}-CN{sub x}CNT composite material has a thermodynamically favorable adsorption and consecutive adsorption energy for ideal reversible adsorption and desorption of hydrogen at room temperature such that it can hold at least 5.8 wt% hydrogen molecules at the LDA and GGA level. - Highlights: • Carbon Nanotube with divacancy (4ND-CN{sub x}NT) decorated with Sc and Ti. • Nitrogen defects, contribute to strong Sc and Ti bindings. • H{sub 2} and (Sc/4ND){sub 10}-CN{sub x}CNT has a favorable adsorption. • 5.8 wt% adsorption at the LDA and GGA level.

  11. Urinary monitoring of exposure to yttrium, scandium, and europium in male Wistar rats.

    Science.gov (United States)

    Kitamura, Yasuhiro; Usuda, Kan; Shimizu, Hiroyasu; Fujimoto, Keiichi; Kono, Rei; Fujita, Aiko; Kono, Koichi

    2012-12-01

    On the assumption that rare earth elements (REEs) are nontoxic, they are being utilized as replacements of toxic heavy metals in novel technological applications. However, REEs are not entirely innocuous, and their impact on health is still uncertain. In the past decade, our laboratory has studied the urinary excretion of REEs in male Wistar rats given chlorides of europium, scandium, and yttrium solutions by one-shot intraperitoneal injection or oral dose. The present paper describes three experiments for the suitability and appropriateness of a method to use urine for biological monitoring of exposure to these REEs. The concentrations of REEs were determined in cumulative urine samples taken at 0-24 h by inductively coupled plasma atomic emission spectroscopy, showing that the urinary excretion of REEs is <2 %. Rare earth elements form colloidal conjugates in the bloodstream, which make high REEs accumulation in the reticuloendothelial system and glomeruli and low urinary excretion. The high sensitivity of inductively coupled plasma-argon emission spectrometry analytical methods, with detection limits of <2 μg/L, makes urine a comprehensive assessment tool that reflects REE exposure. The analytical method and animal experimental model described in this study will be of great importance and encourage further discussion for future studies.

  12. Integrating magneto-optical garnet isolators on semiconductor substrates

    Science.gov (United States)

    Sung, Sang-Yeob

    In optical communications, laser sources need to be protected from unwanted reflected light, a challenge best act by magneto-optical isolators. For integrating magneto-optical isolators with semiconductor devices, including most of these laser sources, it is necessary to develop film fabrication methods that are friendly to batch semiconductor processes. Integrated magneto-optical isolators each consist of a magnetic film layer, optical cladding layers, and a magneto-optical waveguide layer. Traditionally yttrium iron garnet (YIG) films, which are the active layers in magneto-optic isolators, have been grown by thermal deposition process, such as Liquid phase epitaxy (LPE) on garnet substrates. Such thermal processes could damage semiconductor substrates and other semiconductor devices during the deposition, and garnet substrates are difficult to integrate with semiconductor devices. In this work, YIG films were grown by low-temperature RF sputtering onto non-garnet substrates, MgO, fused quartz, and more importantly Si and InP. Two different sputtering methods were used, one involved single target sputtering and the other was multi-target sputtering with a partial pressure differential. After deposition, either post thermal annealing by a conventional tube furnace or a rapid thermal annealing (RTA) was done. To improve the optical characteristics of YIG films, Bi or Ce was substituted into the films. Next, SmCo thin magnetic films were investigated for biasing the active layer. These were grown by RF sputtering. All deposited films were characterized with Energy Dispersive X-ray Spectroscopy (EDS), and X-Ray Diffractometry (XRD), to find atomic composition and crystal structures. Vibrating Sample Magnetometry (VSM) was done for magnetic characterization. Together with integrated photonic crystal polarizer, fully integrated optical isolator can be achieved. Finally, photonic integrated circuits (PIC) and optoelectric integrated circuits (OEIC) can be realized with

  13. Plastic deformation of silicate garnets. I. High-pressure experiments

    Science.gov (United States)

    Voegelé, V.; Ando, J. I.; Cordier, P.; Liebermann, R. C.

    Deformation experiments have been carried out on garnet single crystals (Py20 Al73 Sp2 Gr5) under high confining pressure (6.5 GPa) and temperatures in the range 700-1440°C. The high-pressure sample assembly was designed to generate high differential stress. Below 1000°C, the specimens show only evidence of microplasticity associated with microcracking. Above 1000°C, garnet become ductile and the microstructure is characteristic of dislocation creep with significant recovery. The observed glide systems are 1/2{11¯0}, 1/2{112¯}, 1/2{123¯}, {010} and {011} in the whole temperature range. The most stable (and hence less mobile) dislocation lines appear to be the 70° 1/2 (i.e., with a large edge component) and edge . Except for some rare dislocations generated at low temperature, most of the dislocations exhibit no visible dissociation. The detailed characterization of the dislocations suggests that they have an extended, non-planar core. This core structure induces a high Peierls friction and is responsible for the brittle behavior of garnets at low temperature. The Peierls regime extends up to high temperature until diffusion takes place and enhances dislocation climb superimposed to glide.

  14. Ferroelectricity of domain walls in rare earth iron garnet films.

    Science.gov (United States)

    Popov, A I; Zvezdin, K A; Gareeva, Z V; Mazhitova, F A; Vakhitov, R M; Yumaguzin, A R; Zvezdin, A K

    2016-11-16

    In this paper, we report on electric polarization arising in a vicinity of Bloch-like domain walls in rare-earth iron garnet films. The domain walls generate an intrinsic magnetic field that breaks an antiferroelectric structure formed in the garnets due to an exchange interaction between rare earth and iron sublattices. We explore 180° domain walls whose formation is energetically preferable in the films with perpendicular magnetic anisotropy. Magnetic and electric structures of the 180° quasi-Bloch domain walls have been simulated at various relations between system parameters. Singlet, doublet ground states of rare earth ions and strongly anisotropic rare earth Ising ions have been considered. Our results show that electric polarization appears in rare earth garnet films at Bloch domain walls, and the maximum of magnetic inhomogeneity is not always linked to the maximum of electric polarization. A number of factors including the temperature, the state of the rare earth ion and the type of a wall influence magnetically induced electric polarization. We show that the value of polarization can be enhanced by the shrinking of the Bloch domain wall width, decreasing the temperature, and increasing the deviations of magnetization from the Bloch rotation that are regulated by impacts given by magnetic anisotropies of the films.

  15. Glutathione role in gallium induced toxicity | Ahmad | African Journal ...

    African Journals Online (AJOL)

    The effect of gallium metal on glutathione in blood components was discussed in this study in in vitro condition as a model for in vivo condition. Key words: Gallium nitrate, reduced glutathione (GSH), whole blood, plasma, cytosolic fraction (CF), oxidized glutathione (GSSG), Di-thiobis- dinitro-benzoic acid (DTNB).

  16. Magnetostriction and Magnetic Heterogeneities in Iron-Gallium

    DEFF Research Database (Denmark)

    Laver, Mark; Mudivarthi, C.; Cullen, J.R.

    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 m...

  17. Gallium alloy films investigated for use as boundary lubricants

    Science.gov (United States)

    1966-01-01

    Gallium alloyed with other low melting point metals has excellent lubricant properties of fluidity and low vapor pressure for high temperature or vacuum environments. The addition of other soft metals reduces the corrosivity and formation of undesirable alloys normally found with gallium.

  18. Repurposing of gallium-based drugs for antibacterial therapy.

    Science.gov (United States)

    Bonchi, Carlo; Imperi, Francesco; Minandri, Fabrizia; Visca, Paolo; Frangipani, Emanuela

    2014-01-01

    While the occurrence and spread of antibiotic resistance in bacterial pathogens is vanishing current anti-infective therapies, the antibiotic discovery pipeline is drying up. In the last years, the repurposing of existing drugs for new clinical applications has become a major research area in drug discovery, also in the field of anti-infectives. This review discusses the potential of repurposing previously approved gallium formulations in antibacterial chemotherapy. Gallium has no proven function in biological systems, but it can act as an iron-mimetic in both prokaryotic and eukaryotic cells. The activity of gallium mostly relies on its ability to replace iron in redox enzymes, thus impairing their function and ultimately hampering cell growth. Cancer cells and bacteria are preferential gallium targets due to their active metabolism and fast growth. The wealth of knowledge on the pharmacological properties of gallium has opened the door to the repurposing of gallium-based drugs for the treatment of infections sustained by antibiotic-resistant bacterial pathogens, such as Acinetobacter baumannii or Pseudomonas aeruginosa, and for suppression of Mycobacterium tuberculosis growth. The promising antibacterial activity of gallium both in vitro and in different animal models of infection raises the hope that gallium will confirm its efficacy in clinical trials, and will become a valuable therapeutic option to cure otherwise untreatable bacterial infections. © 2014 International Union of Biochemistry and Molecular Biology.

  19. Gallium in the detection and localization of tumours | Berelowitz ...

    African Journals Online (AJOL)

    The use of Gallium c:trate and gamma-imaging with a gamma camera as a diagnostic procedure for the detection and localization of malignant disease has been evaluated in 64 patients with malignant disease. From the results obtained it can be concluded that Gallium citrate can play an extremely useful diagnostic role as ...

  20. 67Gallium • the D,etection and Localization

    African Journals Online (AJOL)

    1971-12-11

    Dec 11, 1971 ... ]n this article we report the results obtained in scanning patients with malignant disease using ;;'Gallium citrate and we compare our results with those of other published series. MATERIALS AND METHODS. ;;'Gallium citrate was obtained from the Nuclear Physics and Radioactivity Division at the National ...

  1. Superlattice Intermediate Band Solar Cell on Gallium Arsenide

    Science.gov (United States)

    2015-02-09

    AFRL-RV-PS- AFRL-RV-PS- TR-2015-0048 TR-2015-0048 SUPERLATTICE INTERMEDIATE BAND SOLAR CELL ON GALLIUM ARSENIDE Alexandre Freundlich...SUBTITLE 5a. CONTRACT NUMBER FA9453-13-1-0232 Superlattice Intermediate Band Solar Cell on Gallium Arsenide 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER

  2. An inverse modeling strategy and a computer program to model garnet growth and resorption

    Science.gov (United States)

    Lanari, Pierre; Giuntoli, Francesco

    2017-04-01

    GrtMod is a computer program that allows numerical simulation of the pressure-temperature (P-T) evolution of garnet porphyroblasts based on the composition of successive growth zones preserved in natural samples. For each garnet growth stage, a new reactive bulk composition is optimized, allowing for resorption and/or fractionation of the previously crystalized garnet. The successive minimizations are performed using a heuristic search method and an objective function that quantify the amount by which the predicted garnet composition deviates from the measured values. The automated strategy of GrtMod includes a two stages optimization and one refinement stage. In this contribution, we will present several application examples. The new strategy provides quantitative estimates of the optimal P-T conditions whereas it was generally derived in a qualitatively way by using garnet isopleth intersections in equilibrium phase diagrams. GrtMod can also be used to model the evolution of the reactive bulk composition along any P-T trajectories. The results for typical MORB and metapelite compositions demonstrate that fractional crystallization models are required to derive accurate P-T information from garnet compositional zoning. GrtMod can also be used to retrieve complex garnet histories involving several stages of resorption. For instance, it has been used to model the P-T condition of garnet growth in grains from the Sesia Zone (Western Alps). The compositional variability of successive growth zones is characterized using standardized X-ray maps and the program XMapTools. Permian garnet cores crystalized under granulite facies conditions (T > 800°C and P = 6 kbar), whereas Alpine garnet rims grew at eclogite facies conditions (650°C and 16 kbar) involving several successive episodes of resorption. The model predicts that up to 50 vol% of garnet was dissolved before a new episode of garnet growth.

  3. Synthesis of complex oxides with garnet structure by spray drying of an aqueous salt solution

    Science.gov (United States)

    Makeenko, A. V.; Larionova, T. V.; Klimova-Korsmik, O. G.; Starykh, R. V.; Galkin, V. V.; Tolochko, O. V.

    2017-04-01

    The use of spray drying to obtain powders of complex oxides with a garnet structure has demonstrated. The processes occurring during heating of the synthesized oxide-salt product, leading to the formation of a material with a garnet structure, have been investigated using DTA, TGA, XPS, and XRD. It has been shown that a single-phase garnet structure of system (Y x Gd(3- x))3Al5O12 can be synthesized over the entire range of compositions.

  4. Thermal Plasma Synthesis of Crystalline Gallium Nitride Nanopowder from Gallium Nitrate Hydrate and Melamine

    Directory of Open Access Journals (Sweden)

    Tae-Hee Kim

    2016-02-01

    Full Text Available Gallium nitride (GaN nanopowder used as a blue fluorescent material was synthesized by using a direct current (DC non-transferred arc plasma. Gallium nitrate hydrate (Ga(NO33∙xH2O was used as a raw material and NH3 gas was used as a nitridation source. Additionally, melamine (C3H6N6 powder was injected into the plasma flame to prevent the oxidation of gallium to gallium oxide (Ga2O3. Argon thermal plasma was applied to synthesize GaN nanopowder. The synthesized GaN nanopowder by thermal plasma has low crystallinity and purity. It was improved to relatively high crystallinity and purity by annealing. The crystallinity is enhanced by the thermal treatment and the purity was increased by the elimination of residual C3H6N6. The combined process of thermal plasma and annealing was appropriate for synthesizing crystalline GaN nanopowder. The annealing process after the plasma synthesis of GaN nanopowder eliminated residual contamination and enhanced the crystallinity of GaN nanopowder. As a result, crystalline GaN nanopowder which has an average particle size of 30 nm was synthesized by the combination of thermal plasma treatment and annealing.

  5. Thermal Plasma Synthesis of Crystalline Gallium Nitride Nanopowder from Gallium Nitrate Hydrate and Melamine.

    Science.gov (United States)

    Kim, Tae-Hee; Choi, Sooseok; Park, Dong-Wha

    2016-02-24

    Gallium nitride (GaN) nanopowder used as a blue fluorescent material was synthesized by using a direct current (DC) non-transferred arc plasma. Gallium nitrate hydrate (Ga(NO₃)₃∙ x H₂O) was used as a raw material and NH₃ gas was used as a nitridation source. Additionally, melamine (C₃H₆N₆) powder was injected into the plasma flame to prevent the oxidation of gallium to gallium oxide (Ga₂O₃). Argon thermal plasma was applied to synthesize GaN nanopowder. The synthesized GaN nanopowder by thermal plasma has low crystallinity and purity. It was improved to relatively high crystallinity and purity by annealing. The crystallinity is enhanced by the thermal treatment and the purity was increased by the elimination of residual C₃H₆N₆. The combined process of thermal plasma and annealing was appropriate for synthesizing crystalline GaN nanopowder. The annealing process after the plasma synthesis of GaN nanopowder eliminated residual contamination and enhanced the crystallinity of GaN nanopowder. As a result, crystalline GaN nanopowder which has an average particle size of 30 nm was synthesized by the combination of thermal plasma treatment and annealing.

  6. Mineral chemistry of garnet in pegmatite and metamorphic rocks in the Hamedan area

    Directory of Open Access Journals (Sweden)

    Ahmad Ahmadi Khalaji

    2015-10-01

    Full Text Available Introduction The area of this study is located near Hamadan within the Sanandaj - Sirjan tectonic zone. In the Hamadan area, consisting mainly of Mesozoic plutonic and metamorphic rocks, aplites and pegmatites locally contain garnets.(Baharifar et al., 2004, Amidi and Majidi, 1977; Torkian, 1995. Garnet-bearing schists and hornfelses in the area are products of regional metamorphism shown by slate and phyllite (Baharifar, 2004. In this investigation the distribution of elements in garnet in different rock type was studied to determine their mineral types and conditions of formation. Garnet samples from igneous and metamorphic rocks were analyzed by electron microprobe (EMPA, the results of which are presented in this article. Materials and methods Thirty-five samples were selected for thin section preparation and twenty thin-polished sections were prepared for mineralogical and microprobe analysis. Thin sections of garnet-bearing igneous (pegmatite and metamorphic rocks (schist and hornfels were studied by polarizing microscope. Chemical analysis was performed on the garnets (38 points using a Caimeca SX100 electron microprobe at an acceleration voltage of 15 kV and electric current of 15 nA in the Mineral Processing Research Center, Iran. Separation of iron (II and Fe (III was calculated by Droop’s method (1987 and the structural formulas of the garnets were calculated using 24 oxygens to determine the relative proportions of the end-members using the mineral spreadsheet software of Preston and Still (2001. Results Based on the analyses, almandine (Fe - Al garnet and spessartine (Mn - Al garnet are the principal types of the (Kamari metamorphic and (Abaro pegmatitic garnets, that belong to the well-known pyralspite garnet group. Chemical zoning patterns of the garnets in the metamorphic rocks (schists differ from those in the igneous rocks (pegmatite, showing different compositions from core to rim. Petrographic evidence such as: co

  7. Contribution the scintigraphy with gallium 67 in the sarcoidosis; Apport de la scintigraphie au gallium 67 dans la sarcoidose

    Energy Technology Data Exchange (ETDEWEB)

    Elbez, I.; Sellem, A.; Rejeb, O.; Elkadri, N.; Hammami, H. [Service de medecine nucleaire, hopital militaire, Tunis, (Tunisia)

    2009-05-15

    The objective is to show the interest of the scintigraphy with citrates of gallium 67 in the diagnosis and follow up of sarcoidosis injuries. The conclusions are that the scintigraphy with gallium 67 constitutes an imaging technique of good performance, non invasive in the diagnosis, le injuries evaluation and the sarcoidosis follow-up. (N.C.)

  8. Heat blocking gallium arsenide solar cells

    Science.gov (United States)

    Rahman, F.; Farmer, C. D.; Schmidt, C.; Pfaff, G.; Stanley, C. R.

    2008-02-01

    The solar cell industry is witnessing an era of unprecedented growth and this trend is set to continue for the foreseeable future. Here we describe a heat reflection pigment-coated single-junction gallium arsenide solar cell that is capable of reflecting heat-inducing near-infrared radiation. The cell maintains its performance better than non-coated cells when exposed to infrared-rich radiant flux. In situations where solar cells get heated mainly from incident infrared radiation, these cells exhibit superior performance. The heat reflecting pigment, cell structure, coating process and cell performance have been described.

  9. Gallium induces the production of virulence factors in Pseudomonas aeruginosa.

    Science.gov (United States)

    García-Contreras, Rodolfo; Pérez-Eretza, Berenice; Lira-Silva, Elizabeth; Jasso-Chávez, Ricardo; Coria-Jiménez, Rafael; Rangel-Vega, Adrián; Maeda, Toshinari; Wood, Thomas K

    2014-02-01

    The novel antimicrobial gallium is a nonredox iron III analogue with bacteriostatic and bactericidal properties, effective for the treatment of Pseudomonas aeruginosa in vitro and in vivo in mouse and rabbit infection models. It interferes with iron metabolism, transport, and presumably its homeostasis. As gallium exerts its antimicrobial effects by competing with iron, we hypothesized that it ultimately will lead cells to an iron deficiency status. As iron deficiency promotes the expression of virulence factors in vitro and promotes the pathogenicity of P. aeruginosa in animal models, it is anticipated that treatment with gallium will also promote the production of virulence factors. To test this hypothesis, the reference strain PA14 and two clinical isolates from patients with cystic fibrosis were exposed to gallium, and their production of pyocyanin, rhamnolipids, elastase, alkaline protease, alginate, pyoverdine, and biofilm was determined. Gallium treatment induced the production of all the virulence factors tested in the three strains except for pyoverdine. In addition, as the Ga-induced virulence factors are quorum sensing controlled, co-administration of Ga and the quorum quencher brominated furanone C-30 was assayed, and it was found that C-30 alleviated growth inhibition from gallium. Hence, adding both C-30 and gallium may be more effective in the treatment of P. aeruginosa infections. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

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

    Science.gov (United States)

    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.; hide

    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.

  11. Structure-terahertz property relationship in yttrium aluminum garnet ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Steere, D.W.; Clark, B.M.; Sundaram, S.K. [Alfred University, Terahertz and Millimeter Waves Laboratory (T-Lab), Kazuo Inamori School of Engineering, The New York State College of Ceramics, Alfred, NY (United States); Gaume, R. [Townes Laser Institute and the NanoScience Technology Center, CREOL, The College of Optics and Photonics, Orlando, FL (United States)

    2017-08-15

    Terahertz (THz) transmission measurements on chemically variant yttrium aluminum garnet (YAG) ceramics are described. Chemical compositions and processing parameters were varied to determine the effect of stoichiometry, density, and pore volume distribution on the optical and dielectric properties in the THz frequency regime. Density has the largest effect on properties out of the parameters that were investigated. In addition, a linear correlation between cubic root of real permittivity at 1 THz and average density of these samples is observed. Our results show promise for design and fabrication of advanced optical materials and devices with desired THz properties via controlling density and porosity of the materials. (orig.)

  12. Crystallization of pegmatites: Insights from chemistry of garnet, Jacumba pegmatites, San Diego County, California

    Science.gov (United States)

    Thompson, M.; Sirbescu, M. C.

    2013-12-01

    Systematic mineral and textural variations from the border zone to the core of a zoned pegmatite sheet may reflect the kinetic or equilibrium fractionation processes that occurred during sequential crystallization of the pegmatite magma. Rhythmic layering, also named 'line rock', is a salient textural feature of world famous San Diego Co. pegmatites, that consists of alternating garnet × tourmaline layers and albite - quartz layers, mm's to cm's thick. Slowly diffusing, incompatible elements in the felsic magma including B, Fe, and Mn may become enriched in boundary layers formed ahead of rapidly crystallized quartzo-felspathic assemblages. This study explores whether the chemistry of garnet concentrated in the border and foot-wall zones and dispersed in the graphic feldspar, core, and pocket zones of Garnet Ledge pegmatite, Jacumba district, might fingerprint the diffusion-controlled oscillatory boundary layers. The lithium-cesium-tantalum (LCT) Jacumba pegmatite district, late product of the Eastern Peninsular Ranges Batholith, consists of numerous subparallel dikes, 3 to 7 m thick, intruding pre-batholitic metasedimentary rocks. The composite aplite-pegmatite dikes are texturally diverse. Comb-textured tourmaline, other unidirectional textures, garnet × tourmaline 'line rock', and coarse graphic K-feldspar crystals occur in the outer zones, followed by massive feldspar-quartz cores, vuggy cleavlandite- euhedral garnet, and miarolitic cavities. The Jacumba pegmatites have produced gem spodumene, beryl, and garnet from several open cuts such as the Beebe Hole and Pack Rat - Garnet Ledge workings. Systematic mineralogical and textural variations, and SEM-EDS garnet compositions were recorded from border to core at Garnet Ledge outcrop and thin section scale, focusing on continuous traverses across the line rock. Garnet from Garnet Ledge belongs to the spessartine-almandine series (Sp42 to Sp65) with minor contents of Mg, Ca, and Ti, consistent with garnet

  13. A study on the production of high purity gallium (IV)

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Wung; Son, Yong Un; Park, Kyung Ho; Choi, Young Youn; Yoo, Yeon Tae; Nam, Chul Woo [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1996-12-01

    Gallium from GaAs semiconductor scrap was recovered by thermal-decomposition with packing tower type vacuum furnace. And then refined by the electro deposition using fused slat (GaCl{sub 2}). The important result obtained from the study are follows; 1) In the thermal-decomposition process, the recovery of gallium decreased with increasing temperature of the melting point of gallium (1,237 deg. C). At the temperature higher than this, the rate of thermal-decomposition of GaAs became faster and recovery of gallium increased because of the destroy of GaAs structure. 2) The thermal-decomposition of packing tower furnace was carried out with 30 kg sample. The optimum conditions are pressure 5 x 10{sup -2} mmHg, temperature 1,250 deg. C, reaction time 4 hours. At this condition the yield and purity of gallium are higher then 98 % and 99.994 %. 3) The activation energy of fused salt electrorefining for gallium is 16.6 K joule/mole. in the temperature range between 164 deg. C and 197 deg. C. 4) High purity gallium (99.9999%) is obtained at cell voltage 100 mV{approx} 300 mV, current density 1.5 A/cm{sup 2} and the temperature of 473 deg. K with fused GaCl{sub 2}. 5) With purification of GaCl{sub 2} and electro-deposition using fused salt the continues refining process of gallium developed. 6) the flowchart of the high purity gallium recovery process was developed in the study. (author). 24 refs., tabs., figs.

  14. Structural petrology of the garnet-peridotite of Alpe Arami (Ticino, Switzerland)

    NARCIS (Netherlands)

    Möckel, J.R.

    1969-01-01

    The decomposition of pyrope-rich garnet into spinel-amphibole symplektite and the alteration of the latter into chlorite indicate the presence of three successive mineral parageneses in the peridotite of Alpe Arami: a garnet-peridotite, a spinelamphibole-peridotite, and a chlorite-peridotite

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

    Science.gov (United States)

    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.

  16. Negating interfacial impedance in garnet-based solid-state Li metal batteries

    Science.gov (United States)

    Han, Xiaogang; Gong, Yunhui; Fu, Kun (Kelvin); He, Xingfeng; Hitz, Gregory T.; Dai, Jiaqi; Pearse, Alex; Liu, Boyang; Wang, Howard; Rubloff, Gary; Mo, Yifei; Thangadurai, Venkataraman; Wachsman, Eric D.; Hu, Liangbing

    2017-05-01

    Garnet-type solid-state electrolytes have attracted extensive attention due to their high ionic conductivity, approaching 1 mS cm-1, excellent environmental stability, and wide electrochemical stability window, from lithium metal to ~6 V. However, to date, there has been little success in the development of high-performance solid-state batteries using these exceptional materials, the major challenge being the high solid-solid interfacial impedance between the garnet electrolyte and electrode materials. In this work, we effectively address the large interfacial impedance between a lithium metal anode and the garnet electrolyte using ultrathin aluminium oxide (Al2O3) by atomic layer deposition. Li7La2.75Ca0.25Zr1.75Nb0.25O12 (LLCZN) is the garnet composition of choice in this work due to its reduced sintering temperature and increased lithium ion conductivity. A significant decrease of interfacial impedance, from 1,710 Ω cm2 to 1 Ω cm2, was observed at room temperature, effectively negating the lithium metal/garnet interfacial impedance. Experimental and computational results reveal that the oxide coating enables wetting of metallic lithium in contact with the garnet electrolyte surface and the lithiated-alumina interface allows effective lithium ion transport between the lithium metal anode and garnet electrolyte. We also demonstrate a working cell with a lithium metal anode, garnet electrolyte and a high-voltage cathode by applying the newly developed interface chemistry.

  17. Effect of Different Modes of Erbium:yttrium Aluminum Garnet Laser ...

    African Journals Online (AJOL)

    2017-12-05

    Dec 5, 2017 ... surface treatment before application of total etch adhesives is still not an sufficient alternative compared to acid etching. KEYWORDS: Acid etching, dentin conditioning, erbium:yttrium aluminum garnet laser, quantum square pulse mode. Effect of Different Modes of Erbium:yttrium Aluminum Garnet Laser.

  18. Magnetic Force Microscopy Images of Magnetic Garnet With Thin-Film Magnetic Tip

    Science.gov (United States)

    Wadas, A.; Moreland, J.; Rice, P.; Katti, R.

    1993-01-01

    We present magnetic force microscopy images of YGdTmGa/YSmTmGa magnetic garnet, usinga thin Fe film deposited on Si_3N_5 tips. We have found correlations between the topography andthe magnetic domain structure. We have observed the domain wall contrast with a iron thin-film tip. We report on domain wall imaging of garnet with magnetic force microscopy.

  19. Selective recovery of vanadium and scandium by ion exchange with D201 and solvent extraction using P507 from hydrochloric acid leaching solution of red mud.

    Science.gov (United States)

    Zhu, Xiaobo; Li, Wang; Tang, Sen; Zeng, Majian; Bai, Pengyuan; Chen, Lunjian

    2017-05-01

    D201 resin and P507 extractant diluted with sulfonated kerosene were used to respectively separate vanadium and scandium, and impurity ions from hydrochloric acid leaching solution of red mud. More than 99% of vanadium was selectively adsorbed from the hydrochloric acid leaching solution under the conditions of pH value of 1.8, volume ratio of leaching solution to resin of 10, and flow rate of 3.33 mL/min. Maximum extraction and separation of scandium was observed from the acid leaching solution at an aqueous pH value of 0.2. More than 99% of scandium can be selectively extracted using 15% P507, 5% TBP at the aqueous solution/organic phase (A/O) ratio of 10:1 for 6 min. The loaded organic phase was washed with 0.3 mol/L sulfuric acid, wherein most impurities were removed. After the process of desorption or stripping, precipitation, and roasting, high-purity V2O5 and Sc2O3 were obtained. Finally, a conceptual flow sheet was established to separate and recover vanadium and scandium from red mud hydrochloric acid leaching solution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Antitumor effect of novel gallium compounds and efficacy of nanoparticle-mediated gallium delivery in lung cancer.

    Science.gov (United States)

    Wehrung, Daniel; Oyewumi, Moses O

    2012-02-01

    The widespread application of gallium (Ga) in cancer therapy has been greatly hampered by lack of specificity resulting in poor tumor accumulation and retention. To address the challenge, two lipophilic gallium (III) compounds (gallium hexanedione; GaH and gallium acetylacetonate; GaAcAc) were synthesized and antitumor studies were conducted in human lung adenocarcinoma (A549) cells. Nanoparticles (NPs) containing various concentrations of the Ga compounds were prepared using a binary mixture of Gelucire 44/14 and cetyl alcohol as matrix materials. NPs were characterized based on size, morphology, stability and biocompatibility. Antitumor effects of free or NP-loaded Ga compounds were investigated based on cell viability, production of reactive oxygen species and reduction of mitochondrial potential. Compared to free Ga compounds, cytotoxicity of NP-loaded Ga (5-150 microg/ml) was less dependent on concentration and incubation time (exposure) with A549 cells. NP-mediated delivery (5-150 microg Ga/ml) enhanced antitumor effects of Ga compounds and the effect was pronounced at: (i) shorter incubation times; and (ii) at low concentrations of gallium (approximately 50 microg/ml) (p 0.13) suggesting the potential in overcoming gallium resistance in some tumors. In general, preparation of stable and biocompatible NPs that facilitated Ga tumor uptake and antitumor effects could be effective in gallium-based cancer therapy.

  1. Nanogranitoids in garnet clinopyroxenites of the Granulitgebirge (Bohemian Massif): evidence for metasomatism and partial melting?

    Science.gov (United States)

    Borghini, Alessia; Ferrero, Silvio; Wunder, Bernd; O'Brien, Patrick J.; Ziemann, Martin A.

    2017-04-01

    Primary nanogranitoids occur in garnet from the garnet clinopyroxenites of the Granulitgebirge, Bohemian Massif. They form clusters in the inner part of the garnet, and may occur both as polycrystalline and glassy inclusions with size from 5 to 20 µm. Because of their random distribution in garnet these inclusions are interpreted as primary inclusions, thus formed during the growth of the garnet. Garnet does not show any major element zoning. Nanogranitoids were identified in garnet clinopyroxenites from two different locations and show slightly different mineral assemblages. Kumdykolite or albite, phlogopite, osumilite, kokchetavite and a variable amount of quartz occur in both locations. However, osumilite is more abundant in one locality and kokchetavite in the other. All these phases are identified using Raman Spectroscopy. Both assemblages are consistent with the origin of these inclusions as former droplets of melt. Nanogranitoids from one locality have been re-homogenized at 1000°C and 22 kbar to a hydrous glass of granodioritic/quartz-monzonitic composition in a piston cylinder apparatus. The chosen experimental conditions correspond to the formation of the host garnet (O'Brien & Rötzler, 2003) and thus of melt entrapment. Nanogranitoid-bearing garnet clinopyroxenites occur in bodies of serpentinized peridotites, hosted in turn in felsic granulites. The garnet clinopyroxenites show granoblastic texture dominated by garnet and clinopyroxene porphyroblasts with a variable amount of interstitial plagioclase, biotite, two generations of amphiboles (brown and green) and rutile and opaque minerals as accessories. The bulk rock composition is basic to intermediate, and the garnet chemistry varies from 24% Alm, 65% Prp and 11% Grs to 38% Alm, 36% Prp and 26 % Grs between one outcrop and the other. The origin of the investigated inclusions could be due to different processes: localized melting of metasomatized mafic rocks with simultaneous production of garnet or

  2. Effect of annealing temperature on surface morphology and ultralow ferromagnetic resonance linewidth of yttrium iron garnet thin film grown by rf sputtering

    Science.gov (United States)

    Cao Van, Phuoc; Surabhi, Srivathsava; Dongquoc, Viet; Kuchi, Rambabu; Yoon, Soon-Gil; Jeong, Jong-Ryul

    2018-03-01

    We report high-quality yttrium-iron-garnet (YIG; Y3Fe5O12) ultrathin films grown on {111} gadolinium-gallium-garnet (GGG; Gd3Ga5O12) substrates using RF sputtering deposition on an off-stoichiometric target and optimized thermal treatments. We measured a narrow peak-to-peak ferromagnetic resonance linewidth (ΔH) whose minimum value was 1.9 Oe at 9.43 GHz for a 60-nm-thick YIG film. This value is comparable to the most recently published value for a YIG thin film grown by pulsed laser deposition. The temperature dependence of the ΔH was investigated systematically, the optimal annealing condition for our growing condition was 875 °C. Structural analysis revealed that surface roughness and crystallinity played an important role in the observed ΔH broadening. Furthermore, the thickness dependence of the ΔH, which indicated that 60 nm thickness was optimal to obtain narrow ΔH YIG films, was also investigated. The thickness dependence of ΔH was understood on the basis of contributions of surface-associated magnon scattering and magnetic inhomogeneities to the ΔH broadening. Other techniques such as transmission electron microscopy, scanning electron microscopy, and X-ray diffraction were used to study the crystalline structure of the YIG films. The high quality of the films in terms of their magnetic properties was expressed through a very low coercivity and high saturation magnetization measured using a vibration sample magnetometer.

  3. Fabrication of Aluminum Gallium Nitride/Gallium Nitride MESFET And It's Applications in Biosensing

    Science.gov (United States)

    Alur, Siddharth

    Gallium Nitride has been researched extensively for the past three decades for its application in Light Emitting Diodes (LED's), power devices and UV photodetectors. With the recent developments in crystal growth technology and the ability to control the doping there has been an increased interest in heterostructures formed between Gallium nitride and it's alloy Aluminium Gallium Nitride. These heterostructures due to the combined effect of spontaneous and piezoelectric effect can form a high density and a high mobility electron gas channel without any intentional doping. This high density electron gas makes these heterostructures ideal to be used as sensors. Gallium Nitride is also chemically very stable. Detection of biomolecules in a fast and reliable manner is very important in the areas of food safety and medical research. For biomolecular detection it is paramount to have a robust binding of the probes on the sensor surface. Therefore, in this dissertation, the fabrication and application of the AlGaN/GaN heterostructures as biological sensors for the detection of DNA and Organophosphate hydrolase enzyme is discussed. In order to use these AlGaN/GaN heterostructures as biological sensors capable of working in a liquid environment photodefinable polydimethyl-siloxane is used as an encapsulant. The immobilization conditions for a robust binding of thiolated DNA and the catalytic receptor enzyme organophosphate hydrolase on gold surfaces is developed with the help of X-ray photoelectron spectroscopy. DNA and OPH are detected by measuring the change in the drain current of the device as a function of time.

  4. Formation of atoll garnets in the UHP eclogites of the Tso Morari Complex, Ladakh, Himalaya

    Science.gov (United States)

    Jonnalagadda, Mallika K.; Karmalkar, Nitin R.; Duraiswami, Raymond A.; Harshe, Shivani; Gain, Sarah; Griffin, William L.

    2017-12-01

    The eclogites of the Tso Morari Complex, Ladakh, NW Himalayas preserve both garnets with spectacular atoll textures, as well as whole porphyroblastic garnets. Whole garnets are euhedral, idiomorphic and enclose inclusions of amphibole, phengite and zoisite within the cores, and omphacite and quartz/coesite towards the rims. Detailed electron microprobe analyses and back-scattered electron images show well-preserved prograde zoning in the whole garnets with an increase in Mg and decrease in Ca and Mn contents from the core to the rim. The atoll garnets commonly consist of euhedral ring over island/peninsular core containing inclusions of phengite, omphacite and rarely amphibole between the core and ring. Compositional profiles across the studied atoll grains show elemental variations with higher concentrations of Ca and Mn with low Mg at the peninsula/island cores; contrary to this low Ca, Mn and high Mg is observed at the outer rings. Temperature estimates yield higher values at the Mg-rich atoll garnet outer rings compared to the atoll cores. Atoll garnet formation was favoured by infiltration of fluid formed due to breakdown of hydrous phases, and/or the release of structurally bounded OH from nominally anhydrous minerals at the onset of exhumation. Infiltration of fluids along pre-existing fracture pathways and along mineral inclusion boundaries triggered breakdown of the original garnet cores and released elements which were subsequently incorporated into the newly-grown garnet rings. This breakdown of garnet cores and inward re-growth at the outer ring produced the atoll structure. Calibrated geo-thermobarometers and mineral equilibria reflect that the Tso Morari eclogites attain peak pressures prior to peak temperatures representing a clockwise path of evolution.

  5. Gallium (III) and indium (III) dithiolate complexes: Versatile ...

    Indian Academy of Sciences (India)

    The chemistry of classical and organometallic complexes of gallium and indium with dithiolate ligands, i.e., dithiocarboxylates, xanthates, dithiocarbamates, dithiophosphates, dithiophophinates and dithioarsenates, has been reviewed. Synthesis, spectroscopic and structural aspects of these complexes are described.

  6. Usefulness of gallium-67 citrate scanning in testicular seminoma

    Energy Technology Data Exchange (ETDEWEB)

    Willan, B.D.; Penney, H.; Castor, W.R.; McGowan, D.G.

    1987-10-01

    An analysis of 77 consecutive patients with a histologic diagnosis of seminoma testis, assessed and treated at the Cross Cancer Institute between 1977 and 1982, is presented. Ga-67 citrate was first used in the assessment of patients with malignant testicular tumors in 1973. Following three years of study that supported the observation of the gallium-avid nature of seminoma, gallium scans became routine in the initial staging assessment and were used also when recurrence was suspected. From 1977 through 1982, 72 patients with biopsy-proven seminoma testis were assessed initially for extent of disease by Ga-67 scanning. Comparison with intravenous pyelography and bipedal lymphography was possible for accuracy of tumor assessment. The scan sensitivity was 83%, and the specificity was 95%. During the same period, gallium was studied in nonseminomatous testicular tumors but the results were disappointing and its use was discontinued. The gallium-avid nature of seminoma testis may be useful in determining the extent of disease.

  7. Ellipsometric study of silicon nitride on gallium arsenide

    Science.gov (United States)

    Alterovitz, S. A.; Bu-Abbud, G. H.; Woollam, J. A.; Liu, D.; Chung, Y.; Langer, D.

    1982-01-01

    A method for optimizing the sensitivity of ellipsometric measurements for thin dielectric films on semiconductors is described in simple physical terms. The technique is demonstrated for the case of sputtered silicon nitride films on gallium arsenide.

  8. Multiple scaling power in liquid gallium under pressure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Renfeng; Wang, Luhong; Li, Liangliang; Yu, Tony; Zhao, Haiyan; Chapman, Karena W.; Rivers, Mark L.; Chupas, Peter J.; Mao, Ho-kwang; Liu, Haozhe

    2017-06-01

    Generally, a single scaling exponent, Df, can characterize the fractal structures of metallic glasses according to the scaling power law. However, when the scaling power law is applied to liquid gallium upon compression, the results show multiple scaling exponents and the values are beyond 3 within the first four coordination spheres in real space, indicating that the power law fails to describe the fractal feature in liquid gallium. The increase in the first coordination number with pressure leads to the fact that first coordination spheres at different pressures are not similar to each other in a geometrical sense. This multiple scaling power behavior is confined within a correlation length of ξ ≈ 14–15 Å at applied pressure according to decay of G(r) in liquid gallium. Beyond this length the liquid gallium system could roughly be viewed as homogeneous, as indicated by the scaling exponent, Ds, which is close to 3 beyond the first four coordination spheres.

  9. Organo-gallium and indium complexes with dithiolate and oxo ...

    Indian Academy of Sciences (India)

    The chemistry of organo-gallium and indium complexes with dithiolate and internally functionalised oxo ligands has been explored. With 1,1-dithiolate ligands both classical and organometallic complexes of gallium and indium, [M(S ∩ S)3], [RM(S ∩ S)2] and [R2M(S ∩ S)] (where R = Me or Et; M = Ga or In; S ∩ S = RCS2, ...

  10. Dating magmatic and hydrothermal processes using andradite-rich garnet U-Pb geochronometry

    Science.gov (United States)

    Deng, Xiao-Dong; Li, Jian-Wei; Luo, Tao; Wang, Hong-Qiang

    2017-09-01

    Andradite-rich garnet is a common U-bearing mineral in a variety of alkalic igneous rocks and skarn deposits, but has been largely neglected as a U-Pb chronometer. In situ laser ablation-inductively coupled plasma mass spectrometry U-Pb dates of andradite-rich garnet from a syenite pluton and two iron skarn deposits in the North China craton demonstrate the suitability and reliability of the mineral in accurately dating magmatic and hydrothermal processes. Two hydrothermal garnets from the iron skarn deposits have homogenous cores and zoned rims (Ad86Gr11 to Ad98Gr1) with 22-118 ppm U, whereas one magmatic garnet from the syenite is texturally and compositionally homogenous (Ad70Gr22 to Ad77Gr14) and has 0.1-20 ppm U. All three garnets have flat time-resolved signals obtained from depth profile analyses for U, indicating structurally bound U. Uranium is correlated with REE in both magmatic and hydrothermal garnets, indicating that the incorporation of U into the garnet is largely controlled by substitution mechanisms. Two hydrothermal garnets yielded U-Pb dates of 129 ± 2 (2 σ; MSWD = 0.7) and 130 ± 1 Ma (2 σ; MSWD = 0.5), indistinguishable from zircon U-Pb dates of 131 ± 1 and 129 ± 1 Ma for their respective ore-related intrusions. The magmatic garnet has a U-Pb age of 389 ± 3 Ma (2 σ; MSWD = 0.6), consistent with a U-Pb zircon date of 388 ± 2 Ma for the syenite. The consistency between the garnet and zircon U-Pb dates confirms the reliability and accuracy of garnet U-Pb dating. Given the occurrence of andradite-rich garnet in alkaline and ultramafic magmatic rocks and hydrothermal ore deposits, our results highlight the potential utilization of garnet as a powerful U-Pb geochronometer for dating magmatism and skarn-related mineralization.

  11. Gallium Arsenide solar cell radiation damage experiment

    Science.gov (United States)

    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.

  12. Cathodoluminescence spectra of gallium nitride nanorods.

    Science.gov (United States)

    Tsai, Chia-Chang; Li, Guan-Hua; Lin, Yuan-Ting; Chang, Ching-Wen; Wadekar, Paritosh; Chen, Quark Yung-Sung; Rigutti, Lorenzo; Tchernycheva, Maria; Julien, François Henri; Tu, Li-Wei

    2011-12-14

    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.

  13. Surface magnetism of gallium arsenide nanofilms

    Science.gov (United States)

    Lu, Huan; Yu, Jin; Guo, Wanlin

    2017-11-01

    Gallium arsenide (GaAs) is the most widely used second-generation semiconductor with a direct band gap, and it is being increasingly used as nanofilms. However, the magnetic properties of GaAs nanofilms have never been studied. Here we find by comprehensive density-functional-theory calculations that GaAs nanofilms cleaved along the 〈111 〉 and 〈100 〉 directions become intrinsically metallic films with strong surface magnetism and the magnetoelectric effect. Surface magnetism and electrical conductivity are realized via a combined effect of charge transfer induced by spontaneous electric polarization through the film thickness and spin-polarized surface states. The surface magnetism of 〈111 〉 nanofilms can be significantly and linearly tuned by a vertically applied electric field, endowing the nanofilms with unexpectedly high magnetoelectric coefficients, which are tens of times higher than those of ferromagnetic metals and transition-metal oxides.

  14. Inhalation developmental toxicology studies: Gallium arsenide in mice and rats

    Energy Technology Data Exchange (ETDEWEB)

    Mast, T.J.; Greenspan, B.J.; Dill, J.A.; Stoney, K.H.; Evanoff, J.J.; Rommereim, R.L.

    1990-12-01

    Gallium arsenide is a crystalline compound used extensively in the semiconductor industry. Workers preparing solar cells and gallium arsenide ingots and wafers are potentially at risk from the inhalation of gallium arsenide dust. The potential for gallium arsenide to cause developmental toxicity was assessed in Sprague- Dawley rats and CD-1 (Swiss) mice exposed to 0, 10, 37, or 75 mg/m{sup 3} gallium arsenide, 6 h/day, 7 days/week. Each of the four treatment groups consisted of 10 virgin females (for comparison), and {approx}30 positively mated rats or {approx}24 positively mated mice. Mice were exposed on 4--17 days of gestation (dg), and rats on 4--19 dg. The day of plug or sperm detection was designated as 0 dg. Body weights were obtained throughout the study period, and uterine and fetal body weights were obtained at sacrifice (rats, 20 dg; mice, 18 dg). Implants were enumerated and their status recorded. Live fetuses were sexed and examined for gross, visceral, skeletal, and soft-tissue craniofacial defects. Gallium and arsenic concentrations were determined in the maternal blood and uterine contents of the rats (3/group) at 7, 14, and 20 dg. 37 refs., 11 figs., 30 tabs.

  15. Improved dissolution and chemical separation methods for Lu-Hf garnet chronometry

    Science.gov (United States)

    Connelly, J. N.

    2006-04-01

    Garnet-based Lu-Hf geochronology using conventional (HF-HNO3) dissolution methods may be compromised by full or partial digestion of Hf-rich zircon inclusions. This study integrates two complimentary methods to substantially reduce zircon digestion while assuring complete digestion of garnet and sample-spike equilibration. Handpicked garnet fractions are heat treated to >1000°C in an evacuated silica glass ampoule to anneal zircon inclusions and then dissolved with 12 M HCl at 210°C and cold 28 M HF. Analyses of heat-treated garnet (and their high-temperature breakdown products orthopyroxene-spinel-quartz) from Gore Mountain, New York, demonstrate the method is capable of complete dissolution of garnet and routinely achieving sample-spike equilibration. Independent analyses of annealed and unannealed zircons dissolved by HCl - cold HF demonstrate the benefit of heat treatment prior to dissolution. Analyses of zircon-rich garnets from peletic paragneisses of Labrador, Canada, show the potential of this method by returning Lu-Hf ratios commensurate with the degree of heat treatment. Finally, a complementary chemical separation method for Lu and Hf is presented that supports analysis of garnet by MC-ICP-MS.

  16. Random-field Potts model for the polar domains of lead magnesium niobate and lead scandium tantalate

    Energy Technology Data Exchange (ETDEWEB)

    Qian, H.; Bursill, L.A

    1997-06-01

    A random filed Potts model is used to establish the spatial relationship between the nanoscale distribution of charges chemical defects and nanoscale polar domains for the perovskite-based relaxor materials lead magnesium niobate (PMN) and lead scandium tantalate (PST). The random fields are not set stochastically but are determined initially by the distribution of B-site cations (Mg, Nb) or (Sc, Ta) generated by Monte Carlo NNNI-model simulations for the chemical defects. An appropriate random field Potts model is derived and algorithms developed for a 2D lattice. It is shown that the local fields are strongly correlated with the chemical domain walls and that polar domains as a function of decreasing temperature is simulated for the two cases of PMN and PST. The dynamics of the polar clusters is also discussed. 33 refs., 9 figs.

  17. Spodumene and garnet luminescence excited by subnanosecond electron beams

    Science.gov (United States)

    Baksht, E. Kh.; Burachenko, A. G.; Solomonov, V. I.; Tarasenko, V. F.

    2011-11-01

    Pulsed cathodoluminescence of spodumene and yttrium-aluminum garnet crystals activated by Mn2+ and Nd3+ ions, respectively, is investigated. The luminescence was excited upon crystal irradiation by electron beams with current densities of 35 and 100 A/cm2 and average electron energy of ˜ 50 keV for 0.1, 0.25, and 0.65 ns. It is demonstrated that the electron beam duration decreased to several tenth of a nanosecond does not lead to essential changes of the mechanisms of pulsed cathodoluminescence excitation and character of its spectrum, but in this case, the intensity of luminescence of the hole centers increases compared with the intracenter luminescence.

  18. Gallium Potentiates the Antibacterial Effect of Gentamicin against Francisella tularensis.

    Science.gov (United States)

    Lindgren, Helena; Sjöstedt, Anders

    2015-10-26

    The reasons why aminoglycosides are bactericidal have not been not fully elucidated, and evidence indicates that the cidal effects are at least partly dependent on iron. We demonstrate that availability of iron markedly affects the susceptibility of the facultative intracellular bacterium Francisella tularensis strain SCHU S4 to the aminoglycoside gentamicin. Specifically, the intracellular depots of iron were inversely correlated to gentamicin susceptibility, whereas the extracellular iron concentrations were directly correlated to the susceptibility. Further proof of the intimate link between iron availability and antibiotic susceptibility were the findings that a ΔfslA mutant, which is defective for siderophore-dependent uptake of ferric iron, showed enhanced gentamicin susceptibility and that a ΔfeoB mutant, which is defective for uptake of ferrous iron, displayed complete growth arrest in the presence of gentamicin. Based on the aforementioned findings, it was hypothesized that gallium could potentiate the effect of gentamicin, since gallium is sequestered by iron uptake systems. The ferrozine assay demonstrated that the presence of gallium inhibited >70% of the iron uptake. Addition of gentamicin and/or gallium to infected bone marrow-derived macrophages showed that both 100 μM gallium and 10 μg/ml of gentamicin inhibited intracellular growth of SCHU S4 and that the combined treatment acted synergistically. Moreover, treatment of F. tularensis-infected mice with gentamicin and gallium showed an additive effect. Collectively, the data demonstrate that SCHU S4 is dependent on iron to minimize the effects of gentamicin and that gallium, by inhibiting the iron uptake, potentiates the bactericidal effect of gentamicin in vitro and in vivo. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Gallium based low-interaction anions

    Science.gov (United States)

    King, Wayne A.; Kubas, Gregory J.

    2000-01-01

    The present invention provides: a composition of the formula M.sup.+x (Ga(Y).sub.4.sup.-).sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R).sub.x Q.sup.+ Ga(Y).sub.4.sup.- where Q is selected from the group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M.sup.+x.sub.y [X(Ga(Y.sub.3).sub.z ].sup.-y.sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.

  1. Formation of atoll garnets in the UHP eclogites of the Tso Morari ...

    Indian Academy of Sciences (India)

    Mallika K Jonnalagadda

    2017-11-22

    ; Forestier and Lasnier ..... after omphacite (figure 4d); such replacement is very common in eclogites with omphacite that are ...... crops are found retrogressed under amphibolite facies. Textural studies indicate that the garnets.

  2. 40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

    Science.gov (United States)

    2010-07-01

    ... primary and secondary germanium and gallium subcategory. 421.180 Section 421.180 Protection of Environment... POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180 Applicability: Description of the primary and secondary germanium and gallium subcategory. The provisions of this subpart are...

  3. Different origins of garnet in high pressure to ultrahigh pressure metamorphic rocks

    Science.gov (United States)

    Xia, Qiong-Xia; Zhou, Li-Gang

    2017-09-01

    Garnet in high-pressure (HP) to ultrahigh-pressure (UHP) metamorphic rocks in subduction zone commonly shows considerable zonation in major and trace elements as well as mineral inclusions, which bears information on its growth mechanism via metamorphic or peritectic reactions in coexistence with relic minerals and metamorphic fluids or anatectic melts at subduction-zone conditions. It provides an important target to retrieve physicochemical changes in subduction-zone processes, including those not only in pressure and temperature but also in the durations of metamorphism and anatexis. Garnet from different compositions of HP to UHP metamorphic rocks may show different types of major and trace element zonation, as well as mineral inclusions. Discrimination between the different origins of garnet provides important constraints on pressure and temperature and the evolution history for the HP to UHP metamorphic rocks. Magmatic garnet may occur as relics in granitic gneisses despite metamorphic modification at subduction-zone conditions, with spessartine-increasing or flat major element profiles from inner to outer core and exceptionally higher contents of trace elements than metamorphic mantle and rim. Metamorphic garnet can grow at different metamorphic stages during prograde subduction and retrograde exhumation, with spessartine-decreasing from core to rim if the intracrystalline diffusion is not too fast. The compositional profiles of metamorphic garnet in the abundances of grossular, almandine and pyrope are variable depending on the composition of host rocks and co-existing minerals. Peritectic garnet grows through peritectic reactions during partial melting of HP to UHP rocks, with the composition of major elements to be controlled by anatectic P-T conditions and the compositions of parental rocks and anatectic melts. Trace element profiles in garnet with different origins are also variable depending on the coexisting mineral assemblages, the garnet

  4. Caries inhibition around gallium alloy by fluoride releasing resin cement

    Directory of Open Access Journals (Sweden)

    Nasman Nur'alim

    2009-03-01

    Full Text Available Fluoride-releasing materials inhibit secondary caries. Gallium alloy has been developed to replace mercury-based amalgam. The purpose of this study was to test a new F releasing resin-ionomer cement for inhibition of 24 extracted human premolars. The experimental cavity (ARG were filled using etching, priming, and F releasing resin-ionomer cement (All-bond 2 & Presinomer, Bisco followed by condensation of gallium alloy (G Tokuriki Honten, Japan. Three different controls were used: gallium alloy only (G, no etching, Presinomer, gallium alloy (RG, etching, priming, non-F cement (All-bond C&B, Bisco and gallium alloy (ACG The teeth were thermocycled 500x, stored in humidor 28 days, then exposed to artificial caries for 21 days using a strep. mutans culture. Next, they were sectioned and examined by microradiography. The microradiographs were examined for the presence of a caries inhibition zone near the restoration and classified as strongly inhibited (SI, moderately inhibited (MI or not inhibited (N at the enamel and dentin wall. A Chi-square analysis showed that G is different from ARG, ACG is different from ARG, and RG is different from ACG (p<0.05. The results show that the fluoride-releasing resin-ionomer cement provided caries inhibition with or without etching and bonding and that etching and bonding alone is not as effective as fluoride release.

  5. Coesite and diamond inclusions, exsolution microstructures and chemical patterns in ultrahigh pressure garnet from Ceuta (Northern Rif, Spain)

    Science.gov (United States)

    Ruiz-Cruz, M. D.; Sanz de Galdeano, C.

    2013-09-01

    Garnet from diamondiferous granulites of Ceuta (Betic-Rif cordillera, Spain and Morocco) contains a variety of inclusion types. To better understand the evolution of these rocks during the ultrahigh pressure event, two samples (1 and 2) were selected for the detailed study of garnet. Primary inclusions of apatite, quartz, coesite, rutile and retrograded pyroxene, and exsolution microstructures of rutile characterize garnet from sample 1, whereas exsolution microstructures of quartz, coesite, apatite and rutile, and inclusions formed from a melt characterize garnet from sample 2, indicating that peak metamorphic conditions were recorded by sample 2. In contrast, the chemical patterns of garnet suggest an inverse situation. Garnet from sample 1 has high Ca- and low Mn contents and high XMg, characteristic of growth at high pressure and temperature whereas garnet from sample 2 shows high Mn and low Ca contents and low XMg, characteristic of garnet formed at lower temperature and pressure. The contrasting compositions are interpreted as reflecting differences in the position of the metamorphic path followed by both samples relative to the solidus: Garnets from sample 1 are interpreted as formed below the solidus whereas garnets from sample 2 are interpreted as formed in the presence of a melt, which caused notable enrichment of garnet in Mn and depletion in Ca relative to garnet from sample 1. Due to extensive low-pressure Hercynian melting that caused generalized migmatization and melt mobilization, whole-rock composition of the samples notably changed, thus preventing the accurate estimation of the physical conditions characterizing the older ultrahigh pressure event. Estimations based on experimental determinations of the phosphorous solubility in garnet suggest that peak pressure conditions were on the order of 6-7 GPa, which put the origin of the studied crustal rocks at depths greater than 200 km.

  6. Maskless proton beam writing in gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Mistry, P. [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom) and Nano-Electronics Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 7XH (United Kingdom)]. E-mail: p.mistry@surrey.ac.uk; Gomez-Morilla, I. [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom); Smith, R.C. [Nano-Electronics Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 7XH (United Kingdom); Thomson, D. [Advanced Technology Institute, University of Surrey, Guildford GU2 7XH (United Kingdom); Grime, G.W. [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom); Webb, R.P. [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom); Gwilliam, R. [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom); Jeynes, C. [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom); Cansell, A. [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom); Merchant, M. [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom); Kirkby, K.J. [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom)

    2007-07-15

    Proton beam writing (PBW) is a direct write technique that employs a focused MeV proton beam which is scanned in a pre-determined pattern over a target material which is subsequently electrochemically etched or chemically developed. By changing the energy of the protons the range of the protons can be changed. The ultimate depth of the structure is determined by the range of the protons in the material and this allows structures to be formed to different depths. PBW has been successfully employed on etchable glasses, polymers and semiconductor materials such as silicon (Si) and gallium arsenide (GaAs). This study reports on PBW in p-type GaAs and compares experimental results with computer simulations using the Atlas (copy right) semiconductor device package from SILVACO. It has already been proven that hole transport is required for the electrochemical etching of GaAs using Tiron (4,5-dihydroxy-m-benzenedisulfonic acid, di-sodium salt). PBW in GaAs results in carrier removal in the irradiated regions and consequently minimal hole transport (in these regions) during electrochemical etching. As a result the irradiated regions are significantly more etch resistant than the non-irradiated regions. This allows high aspect ratio structures to be formed.

  7. Crystal Orientation Dependence of Gallium Nitride Wear.

    Science.gov (United States)

    Zeng, Guosong; Sun, Wei; Song, Renbo; Tansu, Nelson; Krick, Brandon A

    2017-10-26

    We explore how crystallographic order and orientation affect the tribological (friction and wear) performance of gallium nitride (GaN), through experiments and theory. Friction and wear were measured in every direction on the c-plane of GaN through rotary wear experiment. This revealed a strong crystallographic orientation dependence of the sliding properties of GaN; a 60° periodicity of wear rate and friction coefficient was observed. The origin of this periodicity is rooted in the symmetry presented in wurtzite hexagonal lattice structure of III-nitrides. The lowest wear rate was found as 0.6 × 10 -7 mm 3 /Nm with , while the wear rate associated with had the highest wear rate of 1.4 × 10 -7 mm 3 /Nm. On the contrary, higher friction coefficient can be observed along while lower friction coefficient always appeared along . We developed a simple molecular statics approach to understand energy barriers associated with sliding and material removal; this calculated change of free energy associated with sliding revealed that there were smaller energy barriers sliding along as compared to the direction.

  8. Evaluation of the carcinogenicity of gallium arsenide.

    Science.gov (United States)

    Bomhard, Ernst M; Gelbke, Heinz-Peter; Schenk, Hermann; Williams, Gary M; Cohen, Samuel M

    2013-05-01

    Gallium arsenide (GaAs) is an important semiconductor material. In 2-year inhalation studies, GaAs increased the incidence of lung tumors in female rats, but not in male rats or male and female mice. Alveolar proteinosis followed by chronic active inflammation was the predominant non-neoplastic pulmonary findings. IARC classified GaAs as carcinogenic to humans (group 1) based on the assumption that As and Ga ions are bioavailable. The European Chemical Agency Risk Assessment Committee concluded that GaAs should be classified into Carcinogenicity Category 1B (presumed to have carcinogenic potential for humans; ECHA). We evaluate whether these classifications are justified. Physico-chemical properties of GaAs particles and the degree of mechanical treatment are critical in this evaluation. The available data on mode of action (MOA), genotoxicity and bioavailability do not support the contribution of As or Ga ions to the lung tumors in female rats. Most toxicological studies utilized small particles produced by strong mechanical treatment, destroying the crystalline structure. The resulting amorphous GaAs is not relevant to crystalline GaAs at production and processing sites. The likely tumorigenic MOA is lung toxicity related to particulate-induced inflammation and increased proliferation. It is concluded that there is no evidence for a primary carcinogenic effect of GaAs.

  9. Gallium nitride based logpile photonic crystals.

    Science.gov (United States)

    Subramania, Ganapathi; Li, Qiming; Lee, Yun-Ju; Figiel, Jeffrey J; Wang, George T; Fischer, Arthur J

    2011-11-09

    We demonstrate a nine-layer logpile three-dimensional photonic crystal (3DPC) composed of single crystalline gallium nitride (GaN) nanorods, ∼100 nm in size with lattice constants of 260, 280, and 300 nm with photonic band gap in the visible region. This unique GaN structure is created through a combined approach of a layer-by-layer template fabrication technique and selective metal organic chemical vapor deposition (MOCVD). These GaN 3DPC exhibit a stacking direction band gap characterized by strong optical reflectance between 380 and 500 nm. By introducing a "line-defect" cavity in the fifth (middle) layer of the 3DPC, a localized transmission mode with a quality factor of 25-30 is also observed within the photonic band gap. The realization of a group III nitride 3DPC with uniform features and a band gap at wavelengths in the visible region is an important step toward realizing complete control of the electromagnetic environment for group III nitride based optoelectronic devices.

  10. Simple method for cleaning gallium nitride (0001)

    Science.gov (United States)

    Machuca, Francisco; Liu, Zhi; Sun, Yun; Pianetta, P.; Spicer, W. E.; Pease, R. F. W.

    2002-09-01

    Achieving clean surfaces is a major and challenging requirement for the study of surfaces and surface reactions. We describe the use of synchrotron radiation (SR) to probe the electronic structure of the gallium nitride (GaN) (0001) surface that has undergone wet chemical cleaning sequences followed by heating. By using SR in the range of 200-1000 eV the core levels of Ga, N, O, and C are monitored. Immersion in a 4:1 solution of sulfuric acid (51%) to hydrogen peroxide (30%) followed by a 700 degC (200 degC below decomposition temperature) vacuum anneal (less-than-or-equal10-10 Torr) results in a reduction of carbon and oxygen coverage to a few percent of a monolayer. This suggests a weakly bound oxide of carbon being chemisorbed to the GaN surface after the sulfuric acid/hydrogen peroxide treatment and it is removed by the heating. copyright 2002 American Vacuum Society.

  11. Native gallium adatoms discovered on atomically-smooth gallium nitride surfaces at low temperature.

    Science.gov (United States)

    Alam, Khan; Foley, Andrew; Smith, Arthur R

    2015-03-11

    In advanced compound semiconductor devices, such as in quantum dot and quantum well systems, detailed atomic configurations at the growth surfaces are vital in determining the structural and electronic properties. Therefore, it is important to investigate the surface reconstructions in order to make further technological advancements. Usually, conventional semiconductor surfaces (e.g., arsenides, phosphides, and antimonides) are highly reactive due to the existence of a high density of group V (anion) surface dangling bonds. However, in the case of nitrides, group III rich growth conditions in molecular beam epitaxy are usually preferred leading to group III (Ga)-rich surfaces. Here, we use low-temperature scanning tunneling microscopy to reveal a uniform distribution of native gallium adatoms with a density of 0.3%-0.5% of a monolayer on the clean, as-grown surface of nitrogen polar GaN(0001̅) having the centered 6 × 12 reconstruction. Unseen at room temperature, these Ga adatoms are strongly bound to the surface but move with an extremely low surface diffusion barrier and a high density saturation coverage in thermodynamic equilibrium with Ga droplets. Furthermore, the Ga adatoms reveal an intrinsic surface chirality and an asymmetric site occupation. These observations can have important impacts in the understanding of gallium nitride surfaces.

  12. Raman imaging of fluid inclusions in garnet from UHPM rocks (Kokchetav massif, Northern Kazakhstan).

    Science.gov (United States)

    Korsakov, Andrey V; Dieing, Thomas; Golovin, Aleksandr V; Toporski, Jan

    2011-10-01

    Confocal Raman imaging of fluid inclusions in garnet porphyroblasts from diamond-grade metamorphic calc-silicate rocks from the Kumdy-Kol microdiamond deposit (Kokchetav Massif, Northern Kazakhstan) reveals that these fluid inclusions consist of almost pure water with different step-daughter phases (e.g., calcite, mica and rare quartz). These fluid inclusions are characterized by negative crystal shape of the host-garnet and they exclusively occur within the core of garnet porphyroblasts. These observations are consistent with their primary origin, most likely at ultrahigh-pressure (UHP) metamorphic conditions. The euhedral newly formed garnet, different in color and composition, was found to be associated with these fluid inclusions. It is proposed that newly formed garnet and water fluid inclusions appear by reaction between the hydrous fluid and the garnet-host. These fluid inclusions provide an unequivocal record of almost pure H(2)O fluids, indicating water-saturated conditions within subducted continental crust during prograde stage and/or ultrahigh-P metamorphism. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Development of methods for the selective separation of scandium, zirconium and tin for radiopharmaceutical applications; Entwicklung von Methoden zur selektiven Trennung von Scandium, Zirkonium und Zinn fuer radiopharmazeutische Anwendungen

    Energy Technology Data Exchange (ETDEWEB)

    Dirks-Fandrei, Carina

    2014-07-01

    The subject of the present work is the development of fast and highly selective methods for the separation and purification of scandium, zirconium and tin radionuclides from potential target materials for use in nuclear medicine. A number of selected resins (TrisKem International) were first characterized with respect to their extraction behaviour towards a large number of cations. Characterization studies were performed in batch experiments by determination of weight distribution ratios D{sub w} and further the influence of interferences on the uptake of these elements was evaluated. Weight distribution ratios were determined in different acids and acid concentrations with main focus on scandium, tin or zirconium. The interference of macro amounts of Calcium and Ti on the Sc extraction was evaluated as well as the interference of macro amounts of Y on the Zr extraction. Best suited uptake conditions were found for Scandium on DGA were determined to be 2.5 M HNO{sub 3} for Ti-Targets and 0.1 M HNO{sub 3} for Calcium-Targets. Otherwise it is also possible to extract Sc with TRU Resin. High uptakes were obtained at 2.5 M HNO{sub 3} for simulated Ti- and Calcium-targets. Separation methods were developed using elution studies; employed conditions were chosen according to parameters evaluated in the batch-experiment. The developed methods allowed separating Sc very rapidly in high purity very rapidly from Ti- or Calcium-targets. For Zr a separation method based on UTEVA Resin has been developed. Following results of batch experiments simulated Y-target solution were loaded onto a UTEVA resin column from 6 M HNO{sub 3}; the elution of Zr could be performed in 0.01 M oxalic acid. Decontamination factors in the order of 10{sup 4}-10{sup 5} could be obtained applying the developed method; the method thus allowed separating Zr in a high purity. Initial testing of a method for the separation of Sn from Cd targets based on the use of TBP Resin showed that the TBP resin seems

  14. Competitive segregation of gallium and indium at heterophase Cu-MnO interfaces studied with transmission electron microscopy

    NARCIS (Netherlands)

    Mogck, S.; Kooi, B.J.; de Hosson, J.T.M.

    2003-01-01

    This paper concentrates on the possible segregation of indium and gallium and competitive segregation of gallium and indium at atomically flat parallel {111}-oriented Cu-MnO interfaces. The segregation of gallium at Cu-MnO interfaces after introduction of gallium in the copper matrix of internally

  15. Antibacterial effect of gallium and silver on Pseudomonas aeruginosa treated with gallium-silver-phosphate-based glasses.

    Science.gov (United States)

    Valappil, Sabeel P; Higham, Susan M

    2014-01-01

    Gallium and silver incorporated phosphate-based glasses were evaluated for antibacterial effect on the growth of Pseudomonas aeruginosa, which is a leading cause of opportunistic infections. The glasses were produced by conventional melt quenching methods at 1100°C for 1 h. Glass degradation studies were conducted by weight loss method. Disc diffusion assay and cell viability assay displayed statistically significant (p ≤ 0.0005) effect on P. aeruginosa growth which increased with decreasing calcium content in the glasses. The gallium ion release rates (1.83, 0.69 and 0.48 ppm·h(-1)) and silver ion release rates (2.97, 2.84 and 2.47 ppm·h(-1)) were found to account for this variation. Constant depth film fermentor was used to evaluate the anti-biofilm properties of the glasses. Both gallium and silver in the glass contributed to biofilm growth inhibitory effect on P. aeruginosa (up to 2.68 reduction in log 10 values of the viable counts compared with controls). The glasses were found to deliver gallium and silver in a controlled way and exerted cumulative antibacterial action on planktonic and biofilm growth of P. aeruginosa. The antibacterial, especially anti-biofilm, properties of the gallium and silver incorporated phosphate-based glasses make them a potential candidate to combat infections caused by P. aeruginosa.

  16. Thoracic gallium uptake in patients with lymphomatoid granulomatosis

    Energy Technology Data Exchange (ETDEWEB)

    Tien, R.; Moore, W.H.; Glasser, L.M.; Dhekne, R.D.; Long, S.E.

    1988-12-01

    Lymphomatoid granulomatosis (LG) is a rare condition with histological similarities to Wegener's granulomatosis and malignant lymphoma. Characteristically there is an angiocentric, angiodestructive lymphoreticular cell infiltrate. The lungs are usually affected, and, less frequently, the skin, nervous system, kidney, and bowel are involved. The prognosis is poor and frank lymphoma develops, in some cases terminally. The usual radiological appearance of the lungs consists of bilateral nodular lower zone opacities. The authors report two patients (siblings) with LG, and their gallium scans are presented. In each case there was a significant accumulation of gallium in the lungs at times of clinically active disease. The limited role of gallium imaging in this disease is discussed.

  17. Photoconductive Properties of Brush Plated Copper Indium Gallium Selenide Films

    Directory of Open Access Journals (Sweden)

    N. P. Subiramaniyam

    2013-01-01

    Full Text Available Copper indium gallium selenide (CIGS films were deposited for the first time by the brush electrodeposition technique. X-ray diffraction studies indicated the formation of single phase chalcopyrite CIGS. Lattice parameters, dislocation density, and strain were calculated. Band gap of the films increased from 1.12 eV to 1.63 eV as the gallium concentration increased. Room temperature transport parameters of the films, namely, resistivity increased from 0.10 ohm cm to 12 ohm cm, mobility decreased from 125 cm2V−1s−1 to 20.9 cm2V−1s−1, and carrier concentration decreased from 4.99 × 1017 cm−3 to 2.49 × 1016 cm−3 as the gallium concentration increased. Photosensitivity of the films increased linearly with intensity of illumination and with increase of applied voltage.

  18. Gallium scintigraphy in Hansen's disease

    Energy Technology Data Exchange (ETDEWEB)

    Braga, F.J.H.N. (Hopital Henri-Mondor, 75 - Paris (France). Service de Biophysique de Medecine Nucleaire Sao Paulo Univ., SP (Brazil). Centro de Medicina Nuclear); Araejo, E.B.; Camargo, E.E. (Sao Paulo Univ., SP (Brazil). Centro de Medicina Nuclear); Tedesco-Marchesi, L.C.M.; Rivitti, M.C.M. (Sao Paulo Univ., SP (Brazil). Servicio de Dermatologia); Bouladour, H.; Galle, P. (Hopital Henri-Mondor, 75 - Paris (France). Service de Biophysique de Medecine Nucleaire)

    1991-11-01

    Gallium 67 imaging was used in 12 patients with documented Hansen's disease undergoing treatment or not in an attempt to determine the pattern of the disease. Diagnosis was confirmed by histopathology in all patients. The Mitsuda reaction was seen in all patients. Specific nuclear studies were performed when needed to evaluate particular organs better. Gallium 67 images show homogeneous, diffuse and moderate accumulation over the entire skin surface (except for the face) of untreated patients with multibacillary disease. The face skin in these cases presented homogeneous, diffuse but very marked uptake of gallium. Internal organ involvement was variable. There was a very good correlation among clinical, scintigraphical, immunological and histopathological data. The pattern of the body skin ('skin outlining') and face skin ('beard distribution') may be distinct for untreated patients with multibacillary leprosy. (orig.).

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

    Science.gov (United States)

    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.

  20. Crystallization of high-Ca chromium garnet upon interaction of serpentine, chromite, and Ca-bearing hydrous fluid

    Science.gov (United States)

    Chepurov, A. A.; Turkin, A. I.; Pokhilenko, N. P.

    2017-10-01

    The results of experimental modeling of the conditions of crystallization of high-Ca chromium garnets in the system serpentine-chromite-Ca-Cr-bearing hydrous fluid at a pressure of 5 GPa and temperature of 1300°C are reported. The mineral association including quantitatively predominant high-Mg olivine and diopside-rich clinopyroxene, bright-green garnet, and newly formed chrome spinel was formed. Garnet mostly crystallized around primary chromite grains and was characterized by a high concentration of CaO and Cr2O3. According to the chemical composition, garnets obtained are close to the uvarovite-pyrope varieties, which enter the composition of relatively rare natural paragenesis of garnet wehrlite. The experimental data obtained clearly show that high-Ca chromium garnets are formed in the reaction of chromite-bearing peridotite and Ca-rich fluid at high P-T parameters.

  1. Laser spectroscopy of gallium isotopes using the ISCOOL RFQ cooler

    CERN Multimedia

    Blaum, K; Kowalska, M; Ware, T; Procter, T J

    2007-01-01

    We propose to study the radioisotopes of gallium (Z=31) by collinear laser spectroscopy using the ISCOOL RFQ ion cooler. The proposed measurements on $^{62-83}$Ga will span both neutron-deficient and neutron-rich isotopes. Of key interest is the suggested development of a proton-skin in the neutron-deficient isotopes. The isotope shifts measured by laser spectroscopy will be uniquely sensitive to this feature. The measurements will also provide a wealth of new information on the gallium nuclear spins, static moments and nuclear charge radii.

  2. Renal lymphoma imaged by ultrasound and Gallium-67

    Energy Technology Data Exchange (ETDEWEB)

    Shirkhoda, A.; Staab, E.V.; Mittelstaedt, C.A.

    1980-10-01

    Lymphomatous involvement of the kidneys, usually a secondary process, may be seen as single or multiple sonolucent or weakly echogenic masses on ultrasound. The majority of these patients have a known diagnosis of lymphoma and are being evaluated for change in nodal mass size, flank pain, and/or deteriorating renal function. Occasionally, these masses are discovered on an excretory urogram and are further investigated with ultrasound. The ultrasound findings may be confirmed with gallium scanning. Five such cases are presented along with the ultrasonic and gallium scan findings.

  3. Pseudomembranous colitis: a possible role for Gallium scanning

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Nonlocal magnon-polaron transport in yttrium iron garnet

    Science.gov (United States)

    Cornelissen, L. J.; Oyanagi, K.; Kikkawa, T.; Qiu, Z.; Kuschel, T.; Bauer, G. E. W.; van Wees, B. J.; Saitoh, E.

    2017-09-01

    The spin Seebeck effect (SSE) is observed in magnetic insulator|heavy metal bilayers as an inverse spin Hall effect voltage under a temperature gradient. The SSE can be detected nonlocally as well, viz. in terms of the voltage in a second metallic contact (detector) on the magnetic film, spatially separated from the first contact that is used to apply the temperature bias (injector). Magnon-polarons are hybridized lattice and spin waves in magnetic materials, generated by the magnetoelastic interaction. Kikkawa et al. [Phys. Rev. Lett. 117, 207203 (2016), 10.1103/PhysRevLett.117.207203] interpreted a resonant enhancement of the local SSE in yttrium iron garnet (YIG) as a function of the magnetic field in terms of magnon-polaron formation. Here we report the observation of magnon-polarons in nonlocal magnon spin injection/detection devices for various injector-detector spacings and sample temperatures. Unexpectedly, we find that the magnon-polaron resonances can suppress rather than enhance the nonlocal SSE. Using finite element modeling, we explain our observations as a competition between the SSE and spin diffusion in YIG. These results give unprecedented insights into the magnon-phonon interaction in a key magnetic material.

  5. Construction of an electrode modified with gallium(III) for voltammetric detection of ovalbumin.

    Science.gov (United States)

    Sugawara, Kazuharu; Okusawa, Makoto; Takano, Yusaku; Kadoya, Toshihiko

    2014-01-01

    Electrodes modified with gallium(III) complexes were constructed to detect ovalbumin (OVA). For immobilization of a gallium(III)-nitrilotriacetate (NTA) complex, the electrode was first covered with collagen film. After the amino groups of the film had reacted with isothiocyanobenzyl-NTA, the gallium(III) was then able to combine with the NTA moieties. Another design featured an electrode cast with a gallium(III)-acetylacetonate (AA) complex. The amount of gallium(III) in the NTA complex was equivalent to one-quarter of the gallium(III) that could be utilized from an AA complex. However, the calibration curves of OVA using gallium(III)-NTA and gallium(III)-AA complexes were linear in the ranges of 7.0 × 10(-11) - 3.0 × 10(-9) M and 5.0 × 10(-10) - 8.0 × 10(-9) M, respectively. The gallium(III) on the electrode with NTA complex had high flexibility due to the existence of a spacer between the NTA and the collagen film, and, therefore, the reactivity of the gallium(III) to OVA was superior to that of the gallium(III)-AA complex with no spacer.

  6. Gallium-based anti-infectives: targeting microbial iron-uptake mechanisms.

    Science.gov (United States)

    Kelson, Andrew B; Carnevali, Maia; Truong-Le, Vu

    2013-10-01

    Microbes have evolved elaborate iron-acquisition systems to sequester iron from the host environment using siderophores and heme uptake systems. Gallium(III) is structurally similar to iron(III), except that it cannot be reduced under physiological conditions, therefore gallium has the potential to serve as an iron analog, and thus an anti-microbial. Because Ga(III) can bind to virtually any complex that binds Fe(III), simple gallium salts as well as more complex siderophores and hemes are potential carriers to deliver Ga(III) to the microbes. These gallium complexes represent a new class of anti-infectives that is different in mechanism of action from conventional antibiotics. Simple gallium salts such as gallium nitrate, maltolate, and simple gallium siderophore complexes such as gallium citrate have shown good antibacterial activities. The most studied complex has been gallium citrate, which exhibits broad activity against many Gram negative bacteria at ∼1-5μg/ml MICs, strong biofilm activity, low drug resistance, and efficacy in vivo. Using the structural features of specific siderophore and heme made by pathogenic bacteria and fungi, researchers have begun to evaluate new gallium complexes to target key pathogens. This review will summarize potential iron-acquisition system targets and recent research on gallium-based anti-infectives. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Recovery of gallium and arsenic from gallium arsenide waste in the electronics industry

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei-Ting [Doctoral Program, Graduate School of Engineering Science and Technology, National Yunlin University of Science and Technology (NYUST), Douliou, Yunlin (China); Tsai, Lung-Chang; Shu, Chi-Min [Department of Safety, Health, and Environmental Engineering, NYUST, Douliou, Yunlin (China); Tsai, Fang-Chang [Key Laboratory for the Green Preparation and Application of Functional Materials, Ministry of Education, Faculty of Materials Science and Engineering, Hubei University, Wuhan (China)

    2012-05-15

    Gallium arsenide (GaAs) has both high saturated electron velocity and high electron mobility, making it useful as a semiconductor material in a variety of applications, including light-emitting diodes (LEDs), integrated circuits (ICs), and microwave appliances. A side effect of the use of gallium (Ga) is the production of a relatively large amount of hazardous waste. This study aimed at the recovery of Ga and arsenic (As) from GaAs waste using hydrometallurgical methods involving leaching and coagulation and a dry annealing process that involves annealing, vacuum separation, and sublimation by heating. Our research has shown that GaAs can be leached using nitric acid (HNO{sub 3}) to obtain 100% Ga and As with a leaching solution at pH 0.1, with subsequent adjustment of the leaching solution to pH 3 with sodium hydroxide (NaOH). Another method used a leaching solution at pH 2, then adjusting to pH 11 using NaOH. Ferric hydroxide (FeO(OH)) was added at 90 C after NaOH was added to the leaching solution. At pH 2 and 11, 55.5 and 21.9% of the As could be removed from the hazardous waste, respectively. The Ga could also be precipitated. When GaAs powder was heated to 1000 C over 3 h, 100% As removal was achieved, and 92.6% of the Ga was removed by formation of 99.9% gallium trioxide (Ga{sub 2}O{sub 3}). Arsenic was vaporized when the temperature was elevated to 1000 C, allowing arsenic trioxide (As{sub 2}O{sub 3}) to condense with 99.2% purity. The Ga{sub 2}O{sub 3} powder produced was then dissolved and electrolyzed, allowing for 95.9% recovery of Ga with a purity of 99.9%. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. A NEW INTERPRETATION FOR THE GARNET ZONING IN METAPELITIC ROCKS OF THE SILGARÁ FORMATION, SOUTHWESTERN SANTANDER MASSIF, COLOMBIA

    Directory of Open Access Journals (Sweden)

    Ríos Reyes Carlos Alberto

    2008-06-01

    Full Text Available A Barrovian sequence of the Silgará Formation at the southwestern Santander Massif, Colombian Andes, contains zoned garnets in which major and trace element zoning correlates with distribution of mineral inclusions, which may indicate that garnet growth rate varied through time and affected both composition and texture ofgarnets, although different garnet producing reactions have also played an important role in the chemical zoning of garent. However, a local metasomatism process associated to the action of late magmatic fluids associated to the emplacement of the Pescadero Pluton (external forcing mechanism would be also considered. In particular, Ca, Mn and Y zoning patterns in some garnets correspond with inclusion-rich vs. inclusion-free zones, althoughthe distribution of inclusions does not correlate with chemical zoning (i.e., the same inclusions are found in Ca-rich and Ca-poor zones of the garnet. There is a similar lack of correlation with accessory phases (apatite, monazite, xenotime, ilmenite or rutile. In a garnet from the garnet-staurolite zone, a high Mn core containsabundant and randomly oriented apatite, monazite and ilmenite inclusions, while a euhedral low Ca mantle zone is inclusion-free and the high Ca / low Mn rim zone contains apatite, monazite and ilmenite aligned parallel to the margins of the garnet. Inclusions in garnet can also represent mineral phases were not completely consumed during garnet growth. Association of garnet zoning trends and patterns with inclusion distribution may help differentiatebetween processes that identically affect major-element zoning but that produced variable textures in the garnet.

  9. Gallium arsenide processing for gate array logic

    Science.gov (United States)

    Cole, Eric D.

    1989-01-01

    The development of a reliable and reproducible GaAs process was initiated for applications in gate array logic. Gallium Arsenide is an extremely important material for high speed electronic applications in both digital and analog circuits since its electron mobility is 3 to 5 times that of silicon, this allows for faster switching times for devices fabricated with it. Unfortunately GaAs is an extremely difficult material to process with respect to silicon and since it includes the arsenic component GaAs can be quite dangerous (toxic) especially during some heating steps. The first stage of the research was directed at developing a simple process to produce GaAs MESFETs. The MESFET (MEtal Semiconductor Field Effect Transistor) is the most useful, practical and simple active device which can be fabricated in GaAs. It utilizes an ohmic source and drain contact separated by a Schottky gate. The gate width is typically a few microns. Several process steps were required to produce a good working device including ion implantation, photolithography, thermal annealing, and metal deposition. A process was designed to reduce the total number of steps to a minimum so as to reduce possible errors. The first run produced no good devices. The problem occurred during an aluminum etch step while defining the gate contacts. It was found that the chemical etchant attacked the GaAs causing trenching and subsequent severing of the active gate region from the rest of the device. Thus all devices appeared as open circuits. This problem is being corrected and since it was the last step in the process correction should be successful. The second planned stage involves the circuit assembly of the discrete MESFETs into logic gates for test and analysis. Finally the third stage is to incorporate the designed process with the tested circuit in a layout that would produce the gate array as a GaAs integrated circuit.

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

    Science.gov (United States)

    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

  11. Characterisation of a garnet population from the Sikkim Himalaya: insights into the rates and mechanisms of porphyroblast crystallisation

    Science.gov (United States)

    George, F. R.; Gaidies, F.

    2017-07-01

    The compositional zoning of a garnet population contained within a garnet-grade metapelitic schist from the Lesser Himalayan Sequence of Sikkim (India) provides insight into the rates and kinetic controls of metamorphism, and the extent of chemical equilibration during porphyroblast crystallisation in the sample. Compositional profiles across centrally sectioned garnet crystals representative of the observed crystal size distribution indicate a strong correlation between garnet crystal size and core composition with respect to major end-member components. Systematic steepening of compositional gradients observed from large to small grains is interpreted to reflect a progressive decrease in the growth rate of relatively late-nucleated garnet as a result of an increase in interfacial energies during progressive crystallisation. Numerical simulation of garnet nucleation and growth using an equilibrium approach accounting for chemical fractionation associated with garnet crystallisation reproduces both the observed crystal size distribution and the chemical zoning of the entire garnet population. Simulation of multicomponent intracrystalline diffusion within the population indicates rapid heating along the pressure-temperature path, in excess of 100°C Myr^{-1}. Radial garnet growth is correspondingly rapid, with minimum rates of 1.4 mm Myr^{-1}. As a consequence of such rapid crystallisation, the sample analysed in this study provides a close to primary record of the integrated history of garnet nucleation and growth. Our model suggests that nucleation of garnet occurred continuously between incipient garnet crystallisation at ˜520°C, 4.5 kbar and peak metamorphic conditions at ˜565°C, 5.6 kbar. The good fit between the observed and predicted garnet growth zoning suggests that the departure from equilibrium associated with garnet nucleation and growth was negligible, despite the particularly fast rates of metamorphic heating. Consequently, rates of major element

  12. Reducing Interfacial Resistance between Garnet-Structured Solid-State Electrolyte and Li-Metal Anode by a Germanium Layer.

    Science.gov (United States)

    Luo, Wei; Gong, Yunhui; Zhu, Yizhou; Li, Yiju; Yao, Yonggang; Zhang, Ying; Fu, Kun Kelvin; Pastel, Glenn; Lin, Chuan-Fu; Mo, Yifei; Wachsman, Eric D; Hu, Liangbing

    2017-06-01

    Substantial efforts are underway to develop all-solid-state Li batteries (SSLiBs) toward high safety, high power density, and high energy density. Garnet-structured solid-state electrolyte exhibits great promise for SSLiBs owing to its high Li-ion conductivity, wide potential window, and sufficient thermal/chemical stability. A major challenge of garnet is that the contact between the garnet and the Li-metal anodes is poor due to the rigidity of the garnet, which leads to limited active sites and large interfacial resistance. This study proposes a new methodology for reducing the garnet/Li-metal interfacial resistance by depositing a thin germanium (Ge) (20 nm) layer on garnet. By applying this approach, the garnet/Li-metal interfacial resistance decreases from ≈900 to ≈115 Ω cm(2) due to an alloying reaction between the Li metal and the Ge. In agreement with experiments, first-principles calculation confirms the good stability and improved wetting at the interface between the lithiated Ge layer and garnet. In this way, this unique Ge modification technique enables a stable cycling performance of a full cell of lithium metal, garnet electrolyte, and LiFePO4 cathode at room temperature. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Electrooptic Waveguide Directional Coupler Modulator in Aluminum Gallium Arsenide-Gallium Arsenide.

    Science.gov (United States)

    Khan, Mujibun Nisa

    A novel optical waveguide intensity modulator in aluminum gallium arsenide and gallium arsenide material system is modeled, designed, and experimentally demonstrated at 0.83 μm wavelength. The modulator utilizes the linear electrooptic effect in a coupled waveguide structure to achieve high extinction ratio at low drive voltage. The device structure consists of a differentially -etched ridge directional coupler, where the ridge height in the gap is smaller that that of the outer sides. The effective index and semivectorial finite difference modeling techniques are developed to analyze the single ridge guides and directional coupler structures. The mode structure results from the two models are compared and the limitations of the effective index method are determined. The differential -etch design is employed to reduce the length as well as the drive voltage of the modulator. A modulation voltage of 2 volts for a 3.5-mm-long device is achieved, which is the lowest reported in literature. These results are compared with those obtained from the simplified analytical expressions for conventional couplers, and higher performance expected from the differential-etch design is verified. The modulator extinction ratio is measured to be 13 dB at 2 volts. The measured optical propagation loss of approximately 3.4 dB/cm for the modulator is speculated to be primarily due to the surface morphology of the epitaxially-grown material, and the light scattering from rough ridge walls produced during the anisotropic dry etching process. The high microwave loss of 15 dB/cm calculated for the modulator electrode design suggests a trade-off between the modulation voltage and the bandwidth, which is expected to be limited to 500 MHz. The measurement of the modulator frequency response up to 100 KHz is presented, because of the test limitations at higher frequencies due to the weak modulated intensity signals.

  14. Effect of scandium addition on the microstructure, mechanical and wear properties of the spray formed hypereutectic aluminum–silicon alloys

    Energy Technology Data Exchange (ETDEWEB)

    Raghukiran, Nadimpalli; Kumar, Ravi, E-mail: nvrk@iitm.ac.in

    2015-08-12

    Hypereutectic Al–x%Si–0.8Sc alloys (x=13, 16, 19 and 22 wt%) were produced by spray forming. The microstructures of all the alloys exhibited very fine silicon phase with average size of about 5–10 µm irrespective of the silicon content of the alloy. Transmission electron microscopy revealed the presence of a nano-scale scandium rich phase, identified as AlSi{sub 2}Sc{sub 2} (V-phase) uniformly distributed in the alloy. The presence of V-phase resulted in higher matrix hardness (1.34 GPa) in contrast to 1.04 GPa observed in the case of binary Al–Si alloys by nanoindentation. Isothermal heat treatment at 375 °C revealed insignificant coarsening of silicon phase in both binary and ternary alloys. The Al–x%Si–0.8Sc alloys exhibited higher flow stress and tensile strength in contrast to their binary alloy counterparts which was attributed to the bi-modal size distribution of the strengthening phases in the form of nano-scale V-phase and sub-micron to 10 µm size silicon particles. The pin-on-disk wear tests exhibited appreciable improvement in the wear performance of the relatively low-silicon content ternary alloys over their binary counterparts while the high-silicon content binary and ternary alloys exhibited no much difference in the wear performance.

  15. Scandium and Titanium Containing Single-Walled Carbon Nanotubes for Hydrogen Storage: a Thermodynamic and First Principle Calculation.

    Science.gov (United States)

    Mananghaya, Michael; Yu, Dennis; Santos, Gil Nonato; Rodulfo, Emmanuel

    2016-06-15

    The generalized gradient approximation (GGA) to density functional theory (DFT) calculations indicate that the highly localized states derived from the defects of nitrogen doped carbon nanotube with divacancy (4ND-CNxNT) contribute to strong Sc and Ti bindings, which prevent metal aggregation. Comparison of the H2 adsorption capability of Sc over Ti-decorated 4ND-CNxNT shows that Ti cannot be used for reversible H2 storage due to its inherent high adsorption energy. The Sc/4ND-CNxNT possesses favorable adsorption and consecutive adsorption energy at the local-density approximation (LDA) and GGA level. Molecular dynamics (MD) study confirmed that the interaction between molecular hydrogen and 4ND-CNxNT decorated with scandium is indeed favorable. Simulations indicate that the total amount of adsorption is directly related to the operating temperature and pressure. The number of absorbed hydrogen molecules almost logarithmically increases as the pressure increases at a given temperature. The total excess adsorption of hydrogen on the (Sc/4ND)10-CNxNT arrays at 300 K is within the range set by the department of energy (DOE) with a value of at least 5.85 wt%.

  16. Gallium-Nitride-Based Light-Emitting Diodes

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 7. Gallium-Nitride-Based Light-Emitting Diodes: 2014 Nobel Prize in Physics. Kota V R M Murali Vinayak Bharat Naik Deepanjan Datta. General Article Volume 20 Issue 7 July 2015 pp 605-616 ...

  17. Targeting Gallium to Cancer Cells through the Folate Receptor

    Directory of Open Access Journals (Sweden)

    Nerissa Viola-Villegas

    2008-01-01

    Full Text Available The development of gallium(III compounds as anti-cancer agents for both treatment and diagnosis is a rapidly developing field of research. Problems remain in exploring the full potential of gallium(III as a safe and successful therapeutic agent or as an imaging agent. One of the major issues is that gallium(III compounds have little tropism for cancer cells. We have combined the targeting properties of folic acid (FA with long chain liquid polymer poly(ethylene glycol (PEG 'spacers’. This FA-PEG unit has been coupled to the gallium coordination complex of 1,4,7,10-tetraazacyclo-dodecane-N, N′, N′, N′′-tetraacetic acid (DOTA through amide linkages for delivery into target cells overexpressing the folate receptor (FR. In vitro cytotoxicity assays were conducted against a multi-drug resistant ovarian cell line (A2780/AD that overexpresses the FR and contrasted against a FR free Chinese hamster ovary (CHO cell line. Results are rationalized taking into account stability studies conducted in RPMI 1640 media and HEPES buffer at pH 7.4.

  18. Gallium scintigraphy in the diagnosis and total lymphoid irradiation ...

    African Journals Online (AJOL)

    stranded DNA, antinuclear factor, rheumatoid factor, anticardiolipin ... superimposed uptake of central bony structures sUG:h as the vertebrae and ... Clinical and angio-. TA. Evidence of. Initial. Gallium scan. Surgical. Other management. cF. ;: No, origin. Sex presentation graphic features type tuberculosis. ESR pre TU.

  19. Discovery of Gallium, Germanium, Lutetium, and Hafnium Isotopes

    CERN Document Server

    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.

  20. Targeting Gallium to Cancer Cells through the Folate Receptor

    Directory of Open Access Journals (Sweden)

    Nerissa Viola-Villegas

    2008-01-01

    Full Text Available The development of gallium(III compounds as anti-cancer agents for both treatment and diagnosis is a rapidly developing field of research. Problems remain in exploring the full potential of gallium(III as a safe and successful therapeutic agent or as an imaging agent. One of the major issues is that gallium(III compounds have little tropism for cancer cells. We have combined the targeting properties of folic acid (FA with long chain liquid polymer poly(ethylene glycol (PEG ‘spacers’. This FA-PEG unit has been coupled to the gallium coordination complex of 1,4,7,10-tetraazacyclo-dodecane-N,N′,N′′,N′′′-tetraacetic acid (DOTA through amide linkages for delivery into target cells overexpressing the folate receptor (FR. In vitro cytotoxicity assays were conducted against a multi-drug resistant ovarian cell line (A2780/AD that overexpresses the FR and contrasted against a FR free Chinese hamster ovary (CHO cell line. Results are rationalized taking into account stability studies conducted in RPMI 1640 media and HEPES buffer at pH 7.4.

  1. Isolation and characterization of gallium resistant Pseudomonas aeruginosa mutants

    NARCIS (Netherlands)

    García-Contreras, R; Lira-Silva, E; Jasso-Chávez, R; Hernández-González, I.L.; Maeda, T.; Hashimoto, T.; Boogerd, F.C.; Sheng, L; Wood, TK; Moreno-Sánchez, R

    2013-01-01

    Pseudomonas aeruginosa PA14 cells resistant to the novel antimicrobial gallium nitrate (Ga) were developed using transposon mutagenesis and by selecting spontaneous mutants. The mutants showing the highest growth in the presence of Ga were selected for further characterization. These mutants showed

  2. Electrical and optical properties of silicon-doped gallium nitride ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 31; Issue 1. Electrical and optical properties of silicon-doped gallium nitride polycrystalline films. S R Bhattacharyya A K Pal. Thin Films Volume ... Electrical, optical and microstructural properties were studied for these films. It was observed that films deposited at room ...

  3. Biocompatible nano-gallium/hydroxyapatite nanocomposite with antimicrobial activity.

    Science.gov (United States)

    Kurtjak, Mario; Vukomanović, Marija; Kramer, Lovro; Suvorov, Danilo

    2016-11-01

    Intensive research in the area of medical nanotechnology, especially to cope with the bacterial resistance against conventional antibiotics, has shown strong antimicrobial action of metallic and metal-oxide nanomaterials towards a wide variety of bacteria. However, the important remaining problem is that nanomaterials with highest antibacterial activity generally express also a high level of cytotoxicity for mammalian cells. Here we present gallium nanoparticles as a new solution to this problem. We developed a nanocomposite from bioactive hydroxyapatite nanorods (84 wt %) and antibacterial nanospheres of elemental gallium (16 wt %) with mode diameter of 22 ± 11 nm. In direct comparison, such nanocomposite with gallium nanoparticles exhibited better antibacterial properties against Pseudomonas aeruginosa and lower in-vitro cytotoxicity for human lung fibroblasts IMR-90 and mouse fibroblasts L929 (efficient antibacterial action and low toxicity from 0.1 to 1 g/L) than the nanocomposite of hydroxyapatite and silver nanoparticles (efficient antibacterial action and low toxicity from 0.2 to 0.25 g/L). This is the first report of a biomaterial composite with gallium nanoparticles. The observed strong antibacterial properties and low cytotoxicity make the investigated material promising for the prevention of implantation-induced infections that are frequently caused by P. aeruginosa.

  4. Cellular uptake and anticancer activity of carboxylated gallium corroles.

    Science.gov (United States)

    Pribisko, Melanie; Palmer, Joshua; Grubbs, Robert H; Gray, Harry B; Termini, John; Lim, Punnajit

    2016-04-19

    We report derivatives of gallium(III) tris(pentafluorophenyl)corrole, 1 [Ga(tpfc)], with either sulfonic (2) or carboxylic acids (3, 4) as macrocyclic ring substituents: the aminocaproate derivative, 3 [Ga(ACtpfc)], demonstrated high cytotoxic activity against all NCI60 cell lines derived from nine tumor types and confirmed very high toxicity against melanoma cells, specifically the LOX IMVI and SK-MEL-28 cell lines. The toxicities of 1, 2, 3, and 4 [Ga(3-ctpfc)] toward prostate (DU-145), melanoma (SK-MEL-28), breast (MDA-MB-231), and ovarian (OVCAR-3) cancer cells revealed a dependence on the ring substituent: IC50values ranged from 4.8 to >200 µM; and they correlated with the rates of uptake, extent of intracellular accumulation, and lipophilicity. Carboxylated corroles 3 and 4, which exhibited about 10-fold lower IC50values (gallium corroles by all human cancer cells that followed the order: 4 > 3 > 2 > 1 (intracellular accumulation of gallium corroles was fastest in melanoma cells). We conclude that carboxylated gallium corroles are promising chemotherapeutics with the advantage that they also can be used for tumor imaging.

  5. Growth and characterization of indium antimonide and gallium ...

    Indian Academy of Sciences (India)

    Effect of ampoule shapes and diameters on the crystallinity and homogeneity was studied. The grown crystals were characterized using X-ray analysis, EDAX, chemical etching, Hall effect and conductivity measurements. In the case of gallium antimonide, effect of dopants (Te and In) on transport and photoluminescence ...

  6. Growth and characterization of indium antimonide and gallium ...

    Indian Academy of Sciences (India)

    Unknown

    Growth and characterization of indium antimonide and gallium antimonide crystals. N K UDAYASHANKAR* and H L BHAT†. Department of Physics, Karnataka Regional Engineering College, Surathkal, Srinivasnagar 574 157, India. †Department of Physics, Indian Institute of Science, Bangalore 560 012, India.

  7. Gallium Nitride MMICs for mm-Wave Power Operation

    NARCIS (Netherlands)

    Quay, R.; Maroldt, S.; Haupt, C.; Heijningen, M. van; Tessmann, A.

    2009-01-01

    In this paper a Gallium Nitride MMIC technology for high-power amplifiers between 27 GHz and 101 GHz based on 150 nm- and 100 nm-gate technologies is presented. The GaN HEMT MMICs are designed using coplanar waveguide transmission-line-technology on 3-inch semi-insulating SiC substrates. The

  8. Abnormal gallium scintigraphy in pulmonary alveolar proteinosis (PAP)

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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°, ΔH°f, V and ΔG°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

  10. Experimental Constraints on the Partitioning and Valence of V and Cr in Garnet and Coexisting Glass

    Science.gov (United States)

    Righter, K.; Sutton, S.; Berthet, S.; Newville, M.

    2008-01-01

    A series of experiments with garnet and coexisting melt have been carried out across a range of oxygen fugacities (near hematite-magnetite (HM) to below the iron-wustite (IW) buffers) at 1.7 GPa to study the partitioning and valence of Cr and V in both phases. Experiments were carried out in a non end loaded piston cylinder apparatus, and the run products were analyzed with electron microprobe and xray absorption near edge structure (XANES) analysis at beamline 13-ID at the Advanced Photon Source of Argonne National Lab. The valence of vanadium and chromium were determined using the position and intensity of the Ka pre-edge peaks, calibrated on a series of Cr and Vbearing standard glasses. This technique has been applied to V and Cr in glasses and V in spinels previously, and in these isotropic phases there are no orientational effects on the XANES spectra (Righter et al., 2006, Amer. Mineral. 91, 1643-1656). We also now demonstrate this to be true for V and Cr in garnet. Also, previous work has shown that V has a higher valence in the glass (or melt) than in the coexisting spinel. This is also true for V in garnet-glass pairs in this study. Vanadium valence in garnets varies from 2.7 below the IW buffer to 3.7 near HM, and for coexisting glass it varies from 3.2 to 4.3. Vanadium valence measured in some natural garnets from mantle localities indicates V in the more reduced range at 2.5. Comparisons will be made between fO2 estimated from V valence and other methods for garnet-bearing mantle samples. In contrast, Cr valence measured in garnet and coexisting glass for all experimental and natural samples is 2.9- 3.0, suggesting that the valence of Cr does not vary within either phase across a large fO2 range. These results demonstrate that while V varies from 2+ to 3+ to 4+ in garnet-melt systems, Cr does not, and this will ultimately affect the partitioning behavior of these two elements in natural systems. Garnet/melt D(Cr) are between 12 and 17 across this range

  11. Magneto-Optic Enhancement in Nano-Scale Iron Garnet Films

    Science.gov (United States)

    Chakravarty, Ashim; Levy, Miguel

    This work addresses dimensionality-induced magneto-optic effects in liquid-phase-epitaxy magnetic garnet thin films. It is found that the Faraday rotation (FR) per unit length evinces a marked and steady enhancement as the film thickness is reduced approximately below 100 nm in Bi0.8Gd0.2Lu2Fe5O12, although it remains constant in the micron- and most of the sub-micron-regime. The reported specific FR change in such reduced dimensions is due to size-dependent modifications in diamagnetic transition processes in the garnet film. These processes correspond to the electronic transitions from the singlet 6S ground state to spin-orbit split excited states of the Fe3+ ions in the garnet. A measurable reduction in the corresponding ferrimagnetic resonance linewidths is found, thus pointing to an increase in electronic relaxation times and longer lived excitations at reduced thicknesses than in the bulk. These changes together with a shift in vibrational frequency of the Bi-O bonds in the garnet at reduced thicknesses result in magneto-optical enhancement in ultra-thin garnet films.

  12. Self- and zinc diffusion in gallium antimonide

    Energy Technology Data Exchange (ETDEWEB)

    Nicols, Samuel Piers [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    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

  13. Gallium Oxide Nanostructures for High Temperature Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Chintalapalle, Ramana V. [Univ. of Texas, El Paso, TX (United States)

    2015-04-30

    Gallium oxide (Ga2O3) thin films were produced by sputter deposition by varying the substrate temperature (Ts) in a wide range (Ts=25-800 °C). The structural characteristics and electronic properties of Ga2O3 films were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Rutherford backscattering spectrometry (RBS) and spectrophotometric measurements. The effect of growth temperature is significant on the chemistry, crystal structure and morphology of Ga2O3 films. XRD and SEM analyses indicate that the Ga2O3 films grown at lower temperatures were amorphous while those grown at Ts≥500 oC were nanocrystalline. RBS measurements indicate the well-maintained stoichiometry of Ga2O3 films at Ts=300-800 °C. The electronic structure determination indicated that the nanocrystalline Ga2O3films exhibit a band gap of ~5 eV. Tungsten (W) incorporated Ga2O3 films were produced by co-sputter deposition. W-concentration was varied by the applied sputtering-power. No secondary phase formation was observed in W-incorporated Ga2O3 films. W-induced effects were significant on the structure and electronic properties of Ga2O3 films. The band gap of Ga2O3 films without W-incorporation was ~5 eV. Oxygen sensor characteristics evaluated using optical and electrical methods indicate a faster response in W-doped Ga2O3 films compared to intrinsic Ga2O3 films. The results demonstrate the applicability of both intrinsic and W-doped Ga-oxide films for oxygen sensor application at temperatures ≥700 °C.

  14. Solidus and liquidus temperatures and mineralogies for anhydrous garnet-lherzolite to 15 GPa

    Science.gov (United States)

    Herzberg, C. T.

    1983-01-01

    Strong convergence is noted, in experimental data for systems pertaining to anhydrous fertile garnet-lherzolite in the 6.5-15 GPa range, either to a common temperature or to temperatures differing by only about 100 C. The major element composition of magmas generated by even minor degrees of partial melting may be similar to the composition of the primordial, bulk silicate earth in an upper mantle stratigraphic column more than 160 km deep. Whether or not the solidus and liquidus intersect, the liquidus mineralogy for undepleted garnet-lherzolite compositions is found to change from olivine, at low pressures, to pyroxene, garnet, or a solid solution of both, at pressures greater than 10-15 GPa.

  15. Tunable Optical Nanocavity of Iron-garnet with a Buried Metal Layer

    Directory of Open Access Journals (Sweden)

    Alexey N. Kuz'michev

    2015-05-01

    Full Text Available We report on the fabrication and characterization of a novel magnetophotonic structure designed as iron garnet based magneto-optical nanoresonator cavity constrained by two noble metal mirrors. Since the iron garnet layer requires annealing at high temperatures, the fabrication process can be rather challenging. Special approaches for the protection of metal layers against oxidation and morphological changes along with a special plasma-assisted polishing of the iron garnet layer surface were used to achieve a 10-fold enhancement of the Faraday rotation angle (up to 10.8\\(^{\\circ}/\\mu\\m within a special resonance peak of 12 nm (FWHM linewidth at a wavelength of 772 nm, in the case of a resonator with two silver mirrors. These structures are promising for tunable nanophotonics applications, in particular, they can be used as magneto-optical (MO metal-insulator-metal waveguides and modulators.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  18. U-Pb Geochronology of Grandite Skarn Garnet: Case Studies From Jurassic Skarns of California

    Science.gov (United States)

    Gevedon, M. L.; Seman, S.; Barnes, J.; Stockli, D. F.; Lackey, J. S.

    2016-12-01

    We present 3 case studies using a new method for U-Pb dating grossular-andradite (grandite) skarn garnet via LA-ICP-MS (Seman et al., in prep). Grandite is commonly rich in U, with high Fe3+ contents generally correlating with higher U concentrations. Micron-scale non-radiogenic Pb heterogeneities allow for regression of age data using Tera-Wasserberg concordia. Although others have dated accessory skarn minerals, garnet U-Pb ages are powerful because garnet grows early and is nearly ubiquitous in skarns, resists alteration, and provides a formation age independent of that of the causative pluton. The Darwin stock (Argus range, eastern CA) was likely a short-lived, single pulse of magmatism, genetically related to the Darwin skarn. A robust skarn garnet U-Pb age of 176.8 ± 1.3 Ma agrees well with the pluton U-Pb zircon age of 175 Ma (Chen and Moore, 1982). Furthermore, zircon separated from, and in textural equilibrium with, exoskarn garnetite yields a U-Pb age of 176.8 ± 1 Ma. Such agreement between plutonic and skarn zircon ages with a skarn garnet age in a geologically simple field area is the ideal scenario for establishing grandite U-Pb as a viable tool for directly dating skarns. The Black Rock skarn (BRS; eastern CA) is more complex: multiple plutons and ambiguous field relations complicate determination of a causative pluton. A skarn garnet U-Pb age of 172.0 ± 3 Ma confirms a middle Jurassic BRS formation age. Investigation of 4 local plutons yield zircon U-Pb ages of 222 ± 3 Ma, 213 ± 4 Ma, 207 ± 4 Ma and 176.2 ± 2 Ma. Comparison of the skarn garnet U-Pb and pluton ages suggest the BRS is genetically related to the youngest pluton, providing basis for further field and geochemical investigation. The Whitehorse skarn (WS; Mojave Desert, CA) lies in an important region for studying the changing tectono-magmatic regime of the Jurassic North American Cordillera; basin fill suggests a tectonically-controlled oscillating regional shoreline (Busby, 2012

  19. Selective-Area Micropatterning of Liquid-Phase Epitaxy-Grown Iron Garnet Films

    Science.gov (United States)

    Park, Jae-Hyuk; Cho, Jae-kyeong; Nishimura, Kazuhiro; Uchida, Hironaga; Inoue, Mitsuteru

    2004-07-01

    We investigated selective-area micropatterning of iron garnet film grown by liquid-phase epitaxy (LPE). This method of producing a flat-surface structure overcomes the disadvantages of geometrical grooves, which are formed by wet or dry etching, with a limited resolution due to underetching and nonplanar structure. Moreover, patterned iron garnet films grown by selective-area LPE have better single-crystal properties than films grown by selective-area sputter epitaxy deposition. Thus, this method offers new possibilities for the fabrication of integrated magnetooptic light switch arrays, magnetic waveguides and other magnetooptic devices.

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

    Science.gov (United States)

    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

  1. Influence of gallium on infrared luminescence in Er{sup 3+} doped Yb{sub 3}Al{sub 5−y}Ga{sub y}O{sub 12} films grown by the liquid phase epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Hlásek, T., E-mail: hlasekt@vscht.cz [Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, Prague 6 166 28 (Czech Republic); Rubešová, K.; Jakeš, V.; Nekvindová, P. [Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, Prague 6 166 28 (Czech Republic); Oswald, J. [Institute of Physics v.v.i., Academy of Sciences of the Czech Republic, Cukrovarnická 10, Prague 6 162 00 (Czech Republic); Kučera, M.; Hanuš, M. [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, Prague 2 121 16 (Czech Republic)

    2015-08-15

    Erbium (Er{sup 3+}) doped ytterbium garnet Yb{sub 3}Al{sub 5−y}Ga{sub y}O{sub 12} (y=0, 0.55 and 1.1, YbAGG) thick films were grown by the isothermal liquid phase epitaxy method (LPE) on LuAG or YAG substrates. The influence of gallium on the photoluminescent properties of Er{sup 3+} is presented in this paper. Room temperature transmission and emission spectra were measured for the 0.5 at% Er{sup 3+}:YbAGG films with a different doping level of Ga. Also Er{sup 3+}:Yb{sub 3}Al{sub 3.9}Ga{sub 1.1}O{sub 12} (y=1.1) films with a different doping level of erbium (0.5, 1 and 2 at%) were tested. The presence of gallium significantly affects the fine splitting and total intensity of erbium emission in an infrared region (the transition {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2}). Even at the highest doping level of erbium (2 at%), no up-conversion luminescence was observed, resulting in a maximum efficiency of the infrared emission. The lifetime of luminescence at 1530 nm was studied for all samples. - Highlights: • The presence of gallium is necessary to obtain a waveguide structure. • The presence of Ga enhanced both the absorption of Yb{sup 3+} and IR emission of Er{sup 3+} ions.

  2. In vitro and in vivo biological activities of iron chelators and gallium nitrate against Acinetobacter baumannii.

    Science.gov (United States)

    de Léséleuc, Louis; Harris, Greg; KuoLee, Rhonda; Chen, Wangxue

    2012-10-01

    We investigated the ability of compounds interfering with iron metabolism to inhibit the growth of Acinetobacter baumannii. Iron restriction with transferrin or 2,2-bipyridyl significantly inhibited A. baumannii growth in vitro. Gallium nitrate alone was moderately effective at reducing A. baumannii growth but became bacteriostatic in the presence of serum or transferrin. More importantly, gallium nitrate treatment reduced lung bacterial burdens in mice. The use of gallium-based therapies shows promise for the control of multidrug-resistant A. baumannii.

  3. Structural and magnetic properties of yttrium iron garnet (YIG and yttrium aluminum iron garnet (YAlG nanoferrite via sol-gel synthesis

    Directory of Open Access Journals (Sweden)

    Makiyyu Abdullahi Musa

    Full Text Available The structural and magnetic properties of yttrium iron garnet (YIG and yttrium aluminum iron garnet (Y3AlxFe5−xO12, YAIG (x = 0.2, 0.6, 1, 1.4, 1.8, and 2.2 nanoparticles were investigated. The samples were prepared via auto combustion sol-gel technique, using citric acid as chelating agent and fuel for the combustion process. The obtained powder was heated at 950 °C. X-ray diffraction peaks confirmed the garnet phase formation. Crystallite size increases with Al from 28.5894 to 28.6170 nm. Lattice constant of the samples was found to decrease from 12.4674 Å to 12.3233 Å as Al increase from 0.0 to 2.2. FTIR was used to confirm the garnet structure, the main vibrating modes were observed to shift to higher wave number with increasing Al concentration. Saturation magnetization, Ms shows a decreasing trend from 20.721 to 0.7586 emu/g with increasing Al from 0.0 to 2.2. Furthermore, the decreasing trends in the static magnetic properties of YAIG samples may be due to the introduction of Al ions in the YIG crystal lattice. High content of Al substitution on YIG leads to paramagnetic behavior of the ferrite. The grain size decreased from 0.64 μm to 0.32 μm, while the bulk density decreased from 5.058 gcm−3 to 4.233 gcm−3 as Al increase from 0.0 to 2.2. Keywords: YIG, YAIG, Sol-gel, Phase composition, Magnetic properties

  4. Cutaneous gallium uptake in patients with AIDS with mycobacterium avium-intracellulare septicemia

    Energy Technology Data Exchange (ETDEWEB)

    Allwright, S.J.; Chapman, P.R.; Antico, V.F.; Gruenewald, S.M.

    1988-07-01

    Gallium imaging is increasingly being used for the early detection of complications in patients with AIDS. A 26-year-old homosexual man who was HIV antibody positive underwent gallium imaging for investigation of possible Pneumocystis carinii pneumonia. Widespread cutaneous focal uptake was seen, which was subsequently shown to be due to mycobacterium avium-intracellulare (MAI) septicemia. This case demonstrates the importance of whole body imaging rather than imaging target areas only, the utility of gallium imaging in aiding the early detection of clinically unsuspected disease, and shows a new pattern of gallium uptake in disseminated MAI infection.

  5. Gallium nitrate ameliorates type II collagen-induced arthritis in mice.

    Science.gov (United States)

    Choi, Jae-Hyeog; Lee, Jong-Hwan; Roh, Kug-Hwan; Seo, Su-Kil; Choi, Il-Whan; Park, Sae-Gwang; Lim, Jun-Goo; Lee, Won-Jin; Kim, Myoung-Hun; Cho, Kwang-rae; Kim, Young-Jae

    2014-05-01

    Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease. Gallium nitrate has been reported to reserve immunosuppressive activities. Therefore, we assessed the therapeutic effects of gallium nitrate in the mouse model of developed type II collagen-induced arthritis (CIA). CIA was induced by bovine type II collagen with Complete Freund's adjuvant. CIA mice were intraperitoneally treated from day 36 to day 49 after immunization with 3.5mg/kg/day, 7mg/kg/day gallium nitrate or vehicle. Gallium nitrate ameliorated the progression of mice with CIA. The clinical symptoms of collagen-induced arthritis did not progress after treatment with gallium nitrate. Gallium nitrate inhibited the increase of CD4(+) T cell populations (pGallium nitrate reduced the serum levels of TNF-α, IL-6 and IFN-γ (pgallium nitrate inhibits the activation of NF-κB by blocking IκB degradation. These data suggest that gallium nitrate is a potential therapeutic agent for autoimmune inflammatory arthritis through its inhibition of the NF-κB pathway, and these results may help to elucidate gallium nitrate-mediated mechanisms of immunosuppression in patients with RA. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Evaluation of the in vitro activity of gallium nitrate against Mycobacterium avium subsp paratuberculosis.

    Science.gov (United States)

    Fecteau, Marie-Eve; Fyock, Terry L; McAdams, Susan C; Boston, Raymond C; Whitlock, Robert H; Sweeney, Raymond W

    2011-09-01

    To evaluate the in vitro susceptibility of various field isolates of Mycobacterium avium subsp paratuberculosis (MAP) to gallium nitrate. 10 isolates of MAP, including 4 isolated from cattle, 2 isolated from bison, 1 isolated from an alpaca, and 3 isolated from humans. The in vitro susceptibility to gallium nitrate was tested by use of broth culture with detection of MAP growth by means of a nonradiometric automated detection method. For each MAP isolate, a series of 7 dilutions of gallium nitrate (concentrations ranging from 200 to 1,000 μM) were tested. Gallium nitrate was considered to have caused 90% and 99% inhibition of the MAP growth when the time to detection for culture of the MAP stock solution and a specific concentration of gallium nitrate was delayed and was similar to that obtained for culture of the MAP stock solution (without the addition of gallium nitrate) diluted 1:10 and 1:100, respectively. Gallium nitrate inhibited MAP growth in all 10 isolates. The susceptibility to gallium nitrate was variable among isolates, and all isolates of MAP were inhibited in a dose-dependent manner. Overall, the concentration that resulted in 90% inhibition ranged from Gallium nitrate had activity against all 10 isolates of MAP tested in vitro and could potentially be used as a prophylactic agent to aid in the control of MAP infections during the neonatal period.

  7. Gallium assisted plasma enhanced chemical vapor deposition of silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Zardo, I; Roessler, J; Frimmer, M; Fontcuberta i Morral, A [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, D-85748 Garching (Germany); Yu, L; Alet, Pierre Jean; Roca i Cabarrocas, P [LPICM, Ecole Polytechnique, CNRS, F-91128 Palaiseau (France); Conesa-Boj, S; Estrade, S; Peiro, F; Arbiol, J; Morante, J R [EME/XaRMAE/IN2UB, Departamento d' Electronica, Universitat de Barcelona, MartIi Franques, E-08028, Barcelona (Spain)

    2009-04-15

    Silicon nanowires have been grown with gallium as catalyst by plasma enhanced chemical vapor deposition. The morphology and crystalline structure has been studied by electron microscopy and Raman spectroscopy as a function of growth temperature and catalyst thickness. We observe that the crystalline quality of the wires increases with the temperature at which they have been synthesized. The crystalline growth direction has been found to vary between <111> and <112>, depending on both the growth temperature and catalyst thickness. Gallium has been found at the end of the nanowires, as expected from the vapor-liquid-solid growth mechanism. These results represent good progress towards finding alternative catalysts to gold for the synthesis of nanowires.

  8. Gallium scanning in sarcoidosis. [/sup 67/Ga tracer technique

    Energy Technology Data Exchange (ETDEWEB)

    Israel, H.L.; Park, C.H.; Mansfield, C.M.

    1976-01-01

    The uptake of gallium-67 by pulmonary sarcoidosis was noted by Langhammer et al. in 1972 and by McKusick et al. in 1973. Heshiki et al. studied the application of this procedure in the diagnosis of sarcoidosis and concluded that although gallium-67 uptake in lungs and hilar regions correlated poorly with clinical activity, its measurement might prove useful in the diagnosis of sarcoidosis and in the measurement of response to therapy. We have undertaken to evaluate further the clinical usefulness of this technique. Thirty-six patients, 27 of whom had sarcoidosis, were given intravenous injections of 3 ml of commercially obtained (/sup 67/Ga) citrate. None were receiving corticosteroid therapy at the time of the initial study. Three days later simultaneous anterior and posterior scans of the thorax and the upper abdomen were performed in the supine position. 1 table.

  9. Neutron detection using boron gallium nitride semiconductor material

    Directory of Open Access Journals (Sweden)

    Katsuhiro Atsumi

    2014-03-01

    Full Text Available In this study, we developed a new neutron-detection device using a boron gallium nitride (BGaN semiconductor in which the B atom acts as a neutron converter. BGaN and gallium nitride (GaN samples were grown by metal organic vapor phase epitaxy, and their radiation detection properties were evaluated. GaN exhibited good sensitivity to α-rays but poor sensitivity to γ-rays. Moreover, we confirmed that electrons were generated in the depletion layer under neutron irradiation. This resulted in a neutron-detection signal after α-rays were generated by the capture of neutrons by the B atoms. These results prove that BGaN is useful as a neutron-detecting semiconductor material.

  10. Electrophoretic Deposition of Gallium with High Deposition Rate

    Directory of Open Access Journals (Sweden)

    Hanfei Zhang

    2014-12-01

    Full Text Available In this work, electrophoretic deposition (EPD is reported to form gallium thin film with high deposition rate and low cost while avoiding the highly toxic chemicals typically used in electroplating. A maximum deposition rate of ~0.6 μm/min, almost one order of magnitude higher than the typical value reported for electroplating, is obtained when employing a set of proper deposition parameters. The thickness of the film is shown to increase with deposition time when sequential deposition is employed. The concentration of Mg(NO32, the charging salt, is also found to be a critical factor to control the deposition rate. Various gallium micropatterns are obtained by masking the substrate during the process, demonstrating process compatibility with microfabrication. The reported novel approach can potentially be employed in a broad range of applications with Ga as a raw material, including microelectronics, photovoltaic cells, and flexible liquid metal microelectrodes.

  11. Ultra-low threshold gallium nitride photonic crystal nanobeam laser

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Nan, E-mail: nanniu@fas.harvard.edu; Woolf, Alexander; Wang, Danqing; Hu, Evelyn L. [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Zhu, Tongtong; Oliver, Rachel A. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Quan, Qimin [Rowland Institute at Harvard University, Cambridge, Massachusetts 02142 (United States)

    2015-06-08

    We report exceptionally low thresholds (9.1 μJ/cm{sup 2}) for room temperature lasing at ∼450 nm in optically pumped Gallium Nitride (GaN) nanobeam cavity structures. The nanobeam cavity geometry provides high theoretical Q (>100 000) with small modal volume, leading to a high spontaneous emission factor, β = 0.94. The active layer materials are Indium Gallium Nitride (InGaN) fragmented quantum wells (fQWs), a critical factor in achieving the low thresholds, which are an order-of-magnitude lower than obtainable with continuous QW active layers. We suggest that the extra confinement of photo-generated carriers for fQWs (compared to QWs) is responsible for the excellent performance.

  12. Gallium Nitride Direct Energy Conversion Betavoltaic Modeling and Optimization

    Science.gov (United States)

    2017-03-01

    Gallium Nitride Direct Energy Conversion Betavoltaic Modeling and Optimization William B. Ray II1, Marc S. Litz2, Johnny A. Russo Jr.2, Stephen B...betavoltaic; wide- bandgap betavoltaic; beta-photovoltaic; betaphotovoltaic; tritium; low power high energy battery; betavoltaic battery; Silvaco ATLAS...semiconductor device simulation; MCNPX Introduction A growing problem in power electronics is high energy density, long lasting power sources where the

  13. Trap influence on the performance of gallium arsenide radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Castaldini, A.; Cavallini, A.; Polenta, L. [Univ. of Bologna (Italy); Canali, C.; Nava, F. [Univ. of Modena (Italy); Papa, C. del [Univ. of Udine (Italy). Dept. of Physics

    1996-12-31

    Ohmic contacts play an important role in the performance of LEC gallium arsenide particle detectors since they possibly control the injection of charge carriers. Contact characteristics have been compared and related to electrically active defects induced during contact preparation and to the detector efficiency. The electric field distribution has also been analyzed. Spectroscopic investigations have put into evidence that the contact fabrication process significantly influences the trap density whilst it does not change their signatures.

  14. Pyochelin Potentiates the Inhibitory Activity of Gallium on Pseudomonas aeruginosa

    Science.gov (United States)

    Frangipani, Emanuela; Bonchi, Carlo; Minandri, Fabrizia; Imperi, Francesco

    2014-01-01

    Gallium (Ga) is an iron mimetic that has successfully been repurposed for antibacterial chemotherapy. To improve the antibacterial potency of Ga on Pseudomonas aeruginosa, the effect of complexation with a variety of siderophores and synthetic chelators was tested. Ga complexed with the pyochelin siderophore (at a 1:2 ratio) was more efficient than Ga(NO3)3 in inhibiting P. aeruginosa growth, and its activity was dependent on increased Ga entrance into the cell through the pyochelin translocon. PMID:24957826

  15. Electrodeposition of photoactive 1D gallium selenide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Gujar, T.P. [Clean Energy Research Center, Korea Institute of Science and Technology, Cheongryang, Seoul 130-650 (Korea, Republic of)], E-mail: gujar_tp@yahoo.com; Shinde, V.R. [Clean Energy Research Center, Korea Institute of Science and Technology, Cheongryang, Seoul 130-650 (Korea, Republic of); Park, Jong-Won [Clean Energy Research Center, Korea Institute of Science and Technology, Cheongryang, Seoul 130-650 (Korea, Republic of); The Industrial Chemistry, University of Sang-Myung, Seoul 130-650 (Korea, Republic of); Lee, Hyun Kyung [Industrial Chemistry, University of Sang-Myung, Seoul 130-650 (Korea, Republic of); Jung, Kwang-Deog [Clean Energy Research Center, Korea Institute of Science and Technology, Cheongryang, Seoul 130-650 (Korea, Republic of); Joo, Oh-Shim [Clean Energy Research Center, Korea Institute of Science and Technology, Cheongryang, Seoul 130-650 (Korea, Republic of)], E-mail: joocat@kist.re.kr

    2008-12-30

    One-dimensional (1D) quantum dots of gallium selenide have been obtained by cathodic electrodeposition onto the tin doped indium oxide (ITO) glass substrates from aqueous acidic solutions at room temperature. Characterizations of the as-deposited films by energy dispersive X-ray (EDX) spectroscopy confirm a selenium rich chemistry, X-ray diffraction (XRD) shows that mixture of phases like GaSe/Ga{sub 2}Se{sub 3}, and optical spectroscopy shows a direct optical band gap of 2.85 eV with intermediate transition energy at 1.9 eV. From transmission electron microscopy (TEM), the films show the one-dimensional quantum dots chains in grains. Scanning electron microscopy (SEM) images indicate dimorphous placement of nanoparticles. The elementals surface analysis of the core-shell nanoparticles determined by X-ray photoelectron spectroscopy (XPS) supported the EDX results and confirmed the chemical nature of the material. The photoelectrochemical (PEC) studies of gallium selenide films were carried out and the nanocrystalline gallium selenide films were found to be photoactive in aqueous sodium thiosulphate solution.

  16. Appraisal of lupus nephritis by renal imaging with gallium-67

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Evaluation of the male reproductive toxicity of gallium arsenide.

    Science.gov (United States)

    Bomhard, Ernst M; Cohen, Samuel M; Gelbke, Heinz-Peter; Williams, Gary M

    2012-10-01

    Gallium arsenide is an important semiconductor material marketed in the shape of wafers and thus is not hazardous to the end user. Exposure to GaAs particles may, however, occur during manufacture and processing. Potential hazards require evaluation. In 14-week inhalation studies with small GaAs particles, testicular effects have been reported in rats and mice. These effects occurred only in animals whose lungs showed marked inflammation and also had hematologic changes indicating anemia and hemolysis. The time- and concentration-dependent progressive nature of the lung and blood effects together with bioavailability data on gallium and arsenic lead us to conclude that the testicular/sperm effects are secondary to hypoxemia resulting from lung damage rather than due to a direct chemical effect of gallium or arsenide. Conditions leading to such primary effects are not expected to occur in humans at production and processing sites. This has to be taken into consideration for any classification decision for reproductive toxicity; especially a category 1 according to the EU CLP system is not warranted. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Aqueous stability of Ga- and N-polar gallium nitride.

    Science.gov (United States)

    Foster, Corey M; Collazo, Ramon; Sitar, Zlatko; Ivanisevic, Albena

    2013-01-08

    The stability of III-nitride semiconductors in various solutions becomes important as researchers begin to integrate them into sensing platforms. This study quantitatively compares the stability of GaN surfaces with different polarities. This type of quantification is important because it represents the first step toward designing semiconductor material interfaces compatible with solution conditions. A stability study of Ga- and N-polar GaN was conducted by immersion of the surfaces in deionized H(2)O, pH 5, pH 9, and H(2)O(2) solutions for 7 days. Inductively coupled plasma mass spectrometry of the solutions was conducted to determine the amount of gallium leached from the surface. X-ray photoelectron spectroscopy and atomic force microscopy were used to compare the treated surfaces to untreated surfaces. The results show that both gallium nitride surface types exhibit the greatest stability in acidic and neutral solutions. Gallium polar surfaces were found to exhibit superior stability to nitrogen polar surfaces in the solutions studied. Our findings highlight the need for further research on surface passivation and functionalization techniques for polar III-nitride semiconductors.

  19. Resistive switching characteristics of gallium oxide for nonvolatile memory application

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jyun-Bao [Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Chang, Ting-Chang, E-mail: tcchang@mail.phys.nsysu.edu.tw [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Huang, Jheng-Jie; Chen, Shih-Ching [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Yang, Po-Chun; Chen, Yu-Ting [Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Tseng, Hsueh-Chih [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Sze, Simon M. [Institute of Electronics, National Chiao Tung University, Hsin-Chu, Taiwan (China); Chu, Ann-Kuo [Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Tsai, Ming-Jinn [Electronics and Optoelectronics Research Laboratory, Industrial Technology Research Institute, Chutung, Hsinchu, Taiwan (China)

    2013-02-01

    This study investigates bipolar resistance switching memory in a fabricated Pt/GaO{sub x}/TiN device. Gallium oxide sputtered in ambient Ar shows a change in resistance ratio of two orders of magnitude. The enhancement of resistance ratio is also observed in the gallium oxide layer when deposited in ambient Ar/O{sub 2}. The X-ray photoelectron spectroscopy analysis shows that this gallium oxide in ambient Ar/O{sub 2} can reduce the number of defects and enhance the stability of switching behavior. An analysis of current transport mechanism in the high resistance state indicates that the larger effective thickness can be attributed to the higher oxygen concentration, and can increase the resistance value of the high resistance state. - Highlights: ► Study on the switching mechanisms in a Pt/GaO{sub x}/TiN device ► Pt/GaO{sub x}/TiN exhibits bipolar resistive switching behavior. ► The bipolar behavior originates from conduction associated to oxygen vacancies. ► Additional oxygen can enhance the effective thickness.

  20. Influence of neodymium-doping on structure and properties of yttrium aluminium garnet

    DEFF Research Database (Denmark)

    Zhang, X.D.; He, W.; Yue, Yuanzheng

    2013-01-01

    We study the impact of the Nd-doping on the grain formation, the crystal structure, and the fluorescence of the Yttrium Aluminum Garnet (YAG). The results show that Nd-doping leads to the YAG lattice expansion and distortion, and hence to an increase in defect concentration. This is attributed to...

  1. Optical and magnetic properties of a transparent garnet film for atomic physics experiments

    Directory of Open Access Journals (Sweden)

    Mari Saito

    2016-12-01

    Full Text Available We investigated the optical and magnetic properties of a transparent magnetic garnet with a particular focus on its applications to atomic physics experiments. The garnet film used in this study was a magnetically soft material that was originally designed for a Faraday rotator at optical communication wavelengths in the near infrared region. The film had a thickness of 2.1 μm and a small optical loss at a wavelength of λ=780 nm resonant with Rb atoms. The Faraday effect was also small and, thus, barely affected the polarization of light at λ=780 nm. In contrast, large Faraday rotation angles at shorter wavelengths enabled us to visualize magnetic domains, which were perpendicularly magnetized in alternate directions with a period of 3.6 μm. We confirmed the generation of an evanescent wave on the garnet film, which can be used for the optical observation and manipulation of atoms on the surface of the film. Finally, we demonstrated a magnetic mirror for laser-cooled Rb atoms using the garnet film.

  2. Formation of atoll garnets in the UHP eclogites of the Tso Morari ...

    Indian Academy of Sciences (India)

    Infiltration of fluids along pre-existing fracture pathways and along mineral inclusion boundaries triggered breakdown of the original garnet cores and released ... Calibrated geo-thermobarometers and mineral equilibria reflect that the Tso Morari eclogites attain peak pressures prior to peak temperatures representing a ...

  3. Reaction texture and Fe-Mg zoning in granulite garnet from ...

    Indian Academy of Sciences (India)

    The latter is associated with a Pan-African tectono-metamorphic event that has been interpreted to represent a continent-continent collision followed by extensional collapse. Reaction-diffusion modeling of the compositional zoning of garnet associated with the development of reaction texture during M2 yields a time scale of ...

  4. Single and multiphase inclusions in metapelitic garnets of the Rhodope Metamorphic Province, NE Greece.

    Science.gov (United States)

    Mposkos, Evripidis; Perraki, Maria; Palikari, Sarra

    2009-08-01

    Single and multiphase inclusions in garnet porphyroblasts from the diamond-bearing pelitic gneisses were studied by means of combined Raman Spectroscopy and Electron Scanning Microscopy (SEM/EDX). They are either randomly distributed or with preferred orientation within the garnet host and their dimensions vary from less than 5 up to 60 microm. In the single-phase inclusions quartz, rutile, kyanite and graphite dominate. Biotite, zircon, apatite, monazite and allanite are also common. Two types of multiphase inclusions were recognized, hydrous silicate (Type I) and silicate-carbonate (Type II) ones. The carbon-bearing multiphase inclusions predominantly consist of Mg-siderite+graphite+CO(2)+muscovite+quartz formed by a high density carboniferous fluid rich in Fe, Mg, Si and less Ca, Mn, Al and K trapped in the growing garnet in a prograde stage of metamorphism at high-pressure (HP) conditions. The carbon-free multiphase inclusions predominantly consist of biotite+quartz+rutile+/-kyanite+muscovite formed through decompression-dehydration/melting reactions of pre-existing phengite. Single and multiphase inclusions are characterized by polygonal to negative crystal shape formed by dissolution-reprecipitation mechanism between the garnet host and the inclusions during the long lasting cooling period (>100 Ma) of the Kimi Complex.

  5. Effect of Erbium:yttrium Aluminum Garnet Laser on Bond Strength of ...

    African Journals Online (AJOL)

    2017-06-28

    Jun 28, 2017 ... instrumentation with burs at low and high speeds. In addition to some of the advantages of this ... laser, such as the carbon dioxide laser (CO2 laser, the neodymium:yttrium aluminum garnet (Nd:YAG) ... The concentrated release of energy in the tissue leads to the explosion‑like vaporization of water, with ...

  6. Tibetan garnet records early Eocene initiation of thickening in the Himalaya

    DEFF Research Database (Denmark)

    Smit, Matthijs Arjen; Hacker, Bradley; Lee, Jeffrey

    2014-01-01

    -Hf ages of 54–52 Ma in Mabja and 51–49 Ma in Kangmar samples. On the basis of microstructural and major element and rare earth element zoning observations, the Lu-Hf ages are interpreted as recording garnet growth during contractional deformation in the middle crust at 54.3 ± 0.6 Ma, followed by variable...

  7. Origin of garnet and clinopyroxene in Kaapvaal low-T peridotite xenoliths

    NARCIS (Netherlands)

    Simon, N.S.C.; Irvine, G.J.; Davies, G.R.; Pearson, D.G.; Carlson, R.W.

    2003-01-01

    A detailed petrographic, major and trace element and isotope (Re-Os) study is presented on 18 xenoliths from Northern Lesotho kimberlites. The samples represent typical coarse, low-temperature garnet and spinel peridotites and span a P-T range from ∼60 to 150 km depth. With the exception of one

  8. Challenges for critical raw material recovery from WEEE - The case study of gallium.

    Science.gov (United States)

    Ueberschaar, Maximilian; Otto, Sarah Julie; Rotter, Vera Susanne

    2017-02-01

    Gallium and gallium compounds are more frequently used in future oriented technologies such as photovoltaics, light diodes and semiconductor technology. In the long term the supply risk is estimated to be critical. Germany is one of the major primary gallium producer, recycler of gallium from new scrap and GaAs wafer producer. Therefore, new concepts for a resource saving handling of gallium and appropriate recycling strategies have to be designed. This study focus on options for a possible recycling of gallium from waste electric and electronic equipment. To identify first starting points, a substance flow analysis was carried out for gallium applied in integrated circuits applied on printed circuit boards and for LEDs used for background lighting in Germany in 2012. Moreover, integrated circuits (radio amplifier chips) were investigated in detail to deduce first approaches for a recycling of such components. An analysis of recycling barriers was carried out in order to investigate general opportunities and risks for the recycling of gallium from chips and LEDs. Results show, that significant gallium losses arose in primary production and in waste management. 93±11%, equivalent to 43,000±4700kg of the total gallium potential was lost over the whole primary production process until applied in electronic goods. The largest share of 14,000±2300kggallium was lost in the production process of primary raw materials. The subsequent refining process was related to additional 6900±3700kg and the chip and wafer production to 21,700±3200kg lost gallium. Results for the waste management revealed only low collection rates for related end-of-life devices. Not collected devices held 300 ± 200 kg gallium. Due to the fact, that current waste management processes do not recover gallium, further 80 ± 10 kg gallium were lost. A thermal pre-treatment of the chips, followed by a manual separation allowed an isolation of gallium rich fractions, with gallium mass fractions up to

  9. POLLUTION PREVENTION IN THE SEMICONDUCTOR INDUSTRY THROUGH RECOVERY AND RECYCLING OF GALLIUM AND ARSENIC FROM GAAS POLISHING WASTES

    Science.gov (United States)

    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...

  10. Garnet - two pyroxene rock from the Gridino complex, Russia: a record of the early metasomatic stage

    Science.gov (United States)

    Morgunova, Alena A.; Perchuk, Alexei L.

    2010-05-01

    The Gridino complex is one of the oldest high pressure complexes on the Earth. The most spectacular exposures occur in islands and in a 10-50 m wide belt along the shore of the White Sea in the Gridino area. The exotic blocks show wide range of compositions. In addition to predominating amphibolites and eclogites, there are also peridotites, zoisitites and sapphirine-bearing rocks. The peridotites are represented by garnet - two pyroxene rocks and orthopyroxenites. It this paper we present an intriguing results of the petrological study of the garnet- two pyroxene rock. The garnet- two pyroxene rock considered occurs as elliptical body 4×6 m in size within amphibole-biotite gneiss in the island Visokii. The rock consists of mosaic of coarse-grained primary garnet, clinopyroxene and orthopyroxene. Accessories are represented by magnetite, ilmenite, pyrite and zircon. Garnet contains inclusions of clinopyroxene, Mg-calcite and chlorite. The chlorite inclusions always intergrow with dendritic mineral enriched in REE (mainly Ce) situated on the wall of vacuole which shows the tendency of negative crystal shape. Similar chlorite inclusions are hosted by clino- and orthopyroxenes. The chlorite is of diabantite composition. The inclusions are often surrounded by the two systems of cracks - radial and concentric, which is really exotic phenomenon for crystalline rock. The primary minerals experienced different degree of the retrograde alteration expressed as amphibolization and/or growth of the orthopyroxene-amphibole-garnet symplectites. The retrogression is patchy in the central part of garnet- two pyroxene body, but intensifies towards the rims where primary minerals are absent. Mineral thermobarometry reveals HP rock equilibration at 670-750 оС and 14-20 kbar followed by subisothermal decompression down to 640-740 оС and 6-14 kbar. Specific composition of the chlorite and its association with REE phase in all rock-forming minerals suggests that anhydrous HP

  11. Major and Trace Element Concentrations in Garnet Performed by Electron Microprobe and MicroPIXE

    Science.gov (United States)

    Borghi, A.; Cossio, R.; Mazzoli, C.; Olmi, F.; Vaggelli, G.

    2003-12-01

    The chemical composition of rock-forming minerals reflects their crystallisation history and provides information on the temperature and pressure conditions during their formation. Among metamorphic minerals, garnet is one of the most commonly studied in metamorphic petrology because a chemical zoning is often observed in porphyroblasts that potentially records the changes in the reaction history of the rock. In the past, only major element composition could be determined by non-destructive analytical procedure. However, at high temperature major element growth zoning may be significantly modified by intra-crystalline diffusion. Consequently, the study of trace elements distribution, which may be less susceptible to diffusional modification, becomes of fundamental importance. In this regard, an inverse correlation between yttrium concentration in garnet and metamorphic grade has been recently proposed for pelitic rocks (Pyle & Spear, 2000). This coupling is of great advantage as it may be used to calibrate new geothermometers based on exchange equilibria involving trace elements in garnet In the present paper, a micro-beam Proton Induced X-Ray Emission (micro-PIXE) analytical technique and a WDS electron microprobe (EPMA), were been applied to a specific geological problem particularly affected by the limitations of other techniques. The collected samples come from meta-pelitic samples belonging to the tectonic unit of Monte Rosa Nappe (Western Alps). Selected garnet crystals were analysed for major (Si, Al, Mg, Ca, Mn, Fe) and trace elements. The former were analysed by EPMA and the latter by micro-PIXE. The considered garnet crystals show well-defined compositional zoning, characterised by a smooth and concentric variation of the selected elements from core to rim. As regards the trace elements distribution, the two-dimensional X-ray maps display a strong Y enrichment in the core, followed by a flat pattern at the inner and outer rim. Y concentration spreads over

  12. Comparison of the antimicrobial activities of gallium nitrate and gallium maltolate against Mycobacterium avium subsp. paratuberculosis in vitro.

    Science.gov (United States)

    Fecteau, Marie-Eve; Aceto, Helen W; Bernstein, Lawrence R; Sweeney, Raymond W

    2014-10-01

    Johne's disease (JD) is an enteric infection of cattle and other ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). This study compared the antimicrobial activities of gallium nitrate (GaN) and gallium maltolate (GaM) against two field MAP isolates by use of broth culture. The concentrations that resulted in 99% growth inhibition of isolates 1 and 2 were, respectively, 636 µM and 183 µM for GaN, and 251 µM and 142 µM for GaM. For both isolates, time to detection was significantly higher for GaM than GaN. These results suggest that GaM is more efficient than GaN in inhibiting MAP growth in vitro. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Effects of scandium addition on iron-bearing phases and tensile properties of Al–7Si–0.6Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tzeng, Yu-Chih [Department of Mechanical Engineering, National Central University, Jhongli, Taiwan (China); Wu, Chih-Ting [Department of Vehicle Engineering, Army Academy R.O.C., Jhongli, Taiwan (China); Bor, Hui-Yun; Horng, Jain-Long; Tsai, Mu-Lin [Department of Mechanical Engineering, National Central University, Jhongli, Taiwan (China); Institute of Materials Science and Engineering, National Central University, Jhongli, Taiwan (China); Lee, Sheng-Long, E-mail: shenglon@cc.ncu.edu.tw [Department of Mechanical Engineering, National Central University, Jhongli, Taiwan (China); Institute of Materials Science and Engineering, National Central University, Jhongli, Taiwan (China)

    2014-01-21

    Iron is the most deleterious impurity in aluminum alloys and can easily combine with aluminum to form an acicular β-Al{sub 5}FeSi phase that reduces ductility during the solidification of the molten metal. Adding scandium (Sc) to Al–7Si–0.6Mg alloys can transform the acicular β-Al{sub 5}FeSi phase into a comparatively harmless nodular Sc–Fe phase (Al{sub 12}Si{sub 6}Fe{sub 2}(Mg,Sc){sub 5}). This Sc–Fe phase has a lower hardness and elastic modulus than the β-Al{sub 5}FeSi phase; it is thus less likely to initiate cracks in the Al matrix. Moreover, the nodular Sc–Fe phase can improve the fluidity of Al during solidification, reducing interdendritic shrinkage. Tensile testing measurements showed that the elongation of Al–7Si–0.6Mg alloys with 0.04 and 0.12 wt% Sc can be respectively increased by 115% and 110% compared to Al–7Si–0.6Mg without Sc. The corresponding quality indices are increased by 17% and 19%, respectively, suggesting that the tensile properties of Al–7Si–0.6Mg alloys can be enhanced by adding scandium.

  14. Separation of (44)Ti from proton irradiated scandium by using solid-phase extraction chromatography and design of (44)Ti/(44)Sc generator system.

    Science.gov (United States)

    Radchenko, V; Meyer, C A L; Engle, J W; Naranjo, C M; Unc, G A; Mastren, T; Brugh, M; Birnbaum, E R; John, K D; Nortier, F M; Fassbender, M E

    2016-12-16

    Scandium-44g (half-life 3.97h [1]) shows promise for positron emission tomography (PET) imaging of longer biological processes than that of the current gold standard, (18)F, due to its favorable decay parameters. One source of (44g)Sc is the long-lived parent nuclide (44)Ti (half-life 60.0 a). A (44)Ti/(44g)Sc generator would have the ability to provide radionuclidically pure (44g)Sc on a daily basis. The production of (44)Ti via the (45)Sc(p,2n) reaction requires high proton beam currents and long irradiation times. Recovery and purification of no-carrier added (nca) (44)Ti from scandium metal targets involves complex separation chemistry. In this study, separation systems based on solid phase extraction chromatography were investigated, including branched diglycolamide (BDGA) resin and hydroxamate based ZR resin. Results indicate that ZR resin in HCl media represents an effective (44)Ti/(44g)Sc separation system. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Gallium-67 scanning of malignant lymphomas. Apport de la scintigraphie au gallium-67 dans les lymphomes malins

    Energy Technology Data Exchange (ETDEWEB)

    Cohen-Haguenauer, O.; Brice, P.; Gaci, M.; Le Pailleur, A.; Cheval, E.; Bris, C.; Frija, J.; Gisselbrecht, C.; Rain, J.D.; Najean, Y. (Hopital Saint-Louis, 75 - Paris (France))

    1993-03-01

    The presence of a residual mass is a frequent and difficult problem in the treatment of Hodgkin's or non-Hodgkin's lymphoma: since it is of major importance to determine whether the lesion is a fibrous mass or a still progressing tumour requiring additional therapy. Gallium-67 scanning, performed in a series of 52 patients, provides an answer to this question since there is an excellent correlation between gallium uptake by the tumoral masses and their progressiveness. Magnetic resonance imaging was carried out in half of our patients: the finding of a low-intensity signal on T2-weighted sequences proved that the residual mass was fibrous, whereas a high-intensity signal on T2-weighted sequences did not distinguish between fibrous and tumour masses. The priceless information provided by the simple and non invasive method that is gallium scanning is extremely useful to evaluate the extension of lymphomas and to determine whether residual masses are tumoral or fibrous.

  16. Bis(2-mercapto-1-R-imidazolyl)hydroborato complexes of aluminium, gallium, indium and thallium: compounds possessing gallium-gallium bonds and a trivalent thallium alkyl.

    Science.gov (United States)

    Yurkerwich, Kevin; Coleman, Fergal; Parkin, Gerard

    2010-08-14

    The reactions of bis(mercaptoimidazolyl)hydroborato derivatives [Bm(R)]M' (R = Me, Bu(t); M' = Li, Na, Tl) with MX(3) trihalides of aluminium, gallium and indium yield both 1:1 and 2:1 complexes of the types [Bm(R)]MX(2) and [Bm(R)](2)MX, respectively. Structurally characterized examples of the [Bm(R)]MX(2) series include [Bm(Me)]AlCl(2), [Bm(Me)]GaI(2), [Bm(Me)]InI(2), [Bm(Bu(t))]AlCl(2) and [Bm(Bu(t))]GaX(2) (X = Cl, Br, I), while structurally characterized examples of the [Bm(R)](2)MX series include [Bm(Bu(t))](2)InX (X = Cl, Br, I). In addition to the halide complexes, the trivalent dimethyl thallium complex [Bm(Bu(t))]TlMe(2) has been synthesized via the reaction of [Bm(Bu(t))]Tl with Me(2)TlCl. The reactions of [Bm(R)]M' with the monovalent halides, "GaI", InCl and InI, result in disproportionation. In the case of indium, the mononuclear complexes [Bm(Bu(t))](2)InI and [Bm(Bu(t))]InCl(kappa(2)-mim(Bu(t))) are obtained, whereas for gallium, dinuclear compounds that feature Ga-Ga bonds, namely [Bm(R)](GaI)(GaI)[Bm(R)] (R = Me, Bu(t)) have been isolated.

  17. Growth of epitaxial films of paramagnetic garnets and their characterization by cems and double-crystal diffractometry

    Science.gov (United States)

    Balestrino, G.; Paroli, P.; Antonini, B.; Luce, G.; Maturi, B.

    1987-11-01

    We report on the LPE growth of iron garnet films, paramagnetic at room temperature because of a high substitution (up to 1.7 atoms per formula unit) of diamagnetic Sc 3+ for Fe 3+. For yttrium iron garnet, the maximum amount of Sc 3+ that can be substituted is found to be an increasing function of the growth temperature, and to be little dependent on the Sc concentration in the melt. Simultaneous substitution of La 3+ enhances the maximum Sc 3+ substitution obtainable, and appears to increase the Sc 3+ preference for octahedral garnet sites.

  18. Synthesis and characterization of functional multicomponent nanosized gallium chelated gold crystals.

    Science.gov (United States)

    Zambre, Ajit; Silva, Francisco; Upendran, Anandhi; Afrasiabi, Zahra; Xin, Yan; Paulo, António; Kannan, Raghuraman

    2014-03-28

    In this communication, we describe a novel synthetic method for fabricating multicomponent gold nanoparticles containing both gallium ions and biomolecules on the surface. Detailed compositional analysis, using STEM-HAADF and EELS spectroscopy, confirmed the crystalline nature of gold and chelation of gallium ions. The presence of the biomolecule was validated using conventional ELISA.

  19. Value of Gallium-67 Scanning in Monitoring Therapeutic Effectiveness in a Patient with Relapsing Polychondritis

    Directory of Open Access Journals (Sweden)

    Ming-Che Chang

    2008-06-01

    Full Text Available We present a 57-year-old man who had low-grade fever and painful, swollen and erythematous ears. Gallium-67 citrate scintigraphy (gallium scan performed prior to the commencement of treatment showed increased gallium uptake in bilateral external ears, neck, mediastinum and bilateral pulmonary hili. The results of ultrasonography of both ears were compatible with the diagnosis of chondritis. The patient's clinical condition and laboratory data improved after a course of nonsteroidal anti-inflammatory drugs and steroids. Gallium scan performed after treatment showed a diminished uptake in the external ears, neck, and mediastinum. Gallium scintigraphy is a valuable tool for evaluating inflammatory activity and monitoring therapeutic response in patients with relapsing polychondritis.

  20. Development of anodic stripping voltammetry for determination of gallium in U Ga alloy

    Science.gov (United States)

    Bhardwaj, T. K.; Sharma, H. S.; Aggarwal, S. K.

    2007-03-01

    Deposition potential, deposition time, square-wave frequency, rotation speed of the rotating disc electrode and gallium concentration have been studied in detail, for trace concentration level determination of gallium metal in U-Ga alloy by square-wave voltammetry anodic stripping analysis, in 1 M NaClO 4 + 0.5 M NaSCN at mercury film electrode (MFE). Optimum conditions have been found for Ga(III) determination by obtaining calibration graphs for the range 1-10 × 10 -7 M gallium. Error and standard deviation less than 1% were assessed of this method with all gallium standard solutions. The developed methodology was applied successfully as a subsidiary method for the determination of gallium content in synthetic U-Ga samples with very good precision and accuracy (under 1% error and std. dev.).

  1. The Inhibition of Escherichia coli Biofilm Formation by Gallium Nitrate-Modified Titanium.

    Science.gov (United States)

    Zhu, Yuanyuan; Qiu, Yan; Chen, Ruiqi; Liao, Lianming

    2015-08-01

    Periprosthetic infections are notoriously difficult to treat due to biofilm formation. Previously, we reported that gallium-EDTA attached to PVC (polyvinyl chloride) surface could prevent bacterial colonization. Herein we examined the effect of this gallium-EDTA complex on Escherichia coli biofilm formation on titanium. It was clearly demonstrated that gallium nitrate significantly inhibited the growth and auto-aggregation of Escherichia coli. Furthermore, titanium with gallium-EDTA coating resisted bacterial colonization as indicated by crystal violet staining. When the chips were immersed in human serum and incubated at 37 °C, they demonstrated significant antimicrobial activity after more than 28 days of incubation. These findings indicate that gallium-EDTA coating of implants can result in a surface that can resist bacterial colonization. This technology holds great promise for the prevention and treatment of periprosthetic infections.

  2. Extraction of gallium(III) from hydrochloric acid solutions by trioctylammonium-based mixed ionic liquids.

    Science.gov (United States)

    Katsuta, Shoichi; Okai, Miho; Yoshimoto, Yuki; Kudo, Yoshihiro

    2012-01-01

    The extractabilities of aluminium(III), gallium(III), and indium(III) from hydrochloric acid solutions were investigated using a mixture of two protic ionic liquids, trioctylammonium bis(trifluoromethanesulfonyl)amide ([TOAH][NTf(2)]) and trioctylammonium nitrate ([TOAH][NO(3)]). At a HCl concentration of 4 mol L(-1) or more, gallium(III) was nearly quantitatively extracted and the extractability order was Ga > Al > In. The extractability of gallium(III) increased with increasing [TOAH][NO(3)] content in the mixed ionic liquid. The extracted gallium(III) was quantitatively stripped with aqueous nitric acid solutions. The separation and recovery of gallium(III) from hydrochloric acid solutions containing excess indium(III) was demonstrated using the mixed ionic liquid.

  3. Synthesis and characterization of gallium oxide nanowires via a hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Quan Yu; Fang Dong; Zhang Xueying; Liu Suqin [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Huang Kelong, E-mail: csufangdong@gmail.com [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2010-05-15

    Single-crystalline gallium oxide hydroxide (GaOOH) nanowires could be successfully synthesized in large quantities through a hydrothermal synthetic method using gallium nitrate as the gallium source and sodium dodecyl benzene sulfonate as the surfactant. Gallium oxide {alpha}-Ga{sub 2}O{sub 3} and {beta}-Ga{sub 2}O{sub 3} nanowires could be obtained by thermal decomposition method using gallium oxide hydroxide nanowires as the precursor. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), energy-dispersive X-ray (EDX) analysis, Fourier-transform infrared (FTIR) spectra, and photoluminescence (PL) were employed to characterize the resulting samples. Detailed results and possible mechanism are presented.

  4. Quantitative Prograde P-T Paths From Inclusion Assemblages in Eclogitic Garnets

    Science.gov (United States)

    Essene, E. J.; Page, F. Z.; Mukasa, S. B.

    2003-12-01

    Many workers have used garnet inclusions as qualitative indicators of the early history of tectonically exposed eclogites. Assemblages indicative of crustal facies combined with standard P-T conditions of those facies and thermobarometry on the matrix eclogite constrain the prograde path. However, now that conditions of some blueschist, amphibolite and granulite facies rocks have been extended to much higher pressures, in the range of 10-20 kbar, those assignments are in need of review. While undertaking studies on eclogites from the Blue Ridge of North Carolina and the Franciscan in northern California, the authors have identified key inclusion assemblages of sphene-rutile-epidote-quartz and phengite-omphacite together with garnet that constrain the prograde P-T path based on univariant assemblages corrected for observed solid solutions. Equilibria that have proved most useful are those bounding epidote stability and two key reactions, one involving sphene/rutile: (1) clinozoisite + sphene = grossular + rutile + H2O, and the second being the phengite barometer: garnet + Mg-celadonite = clinopyroxene + muscovite. Reactions (1) and (2) have negative slopes, intersecting with the Mg/Fe KD garnet-clinopyroxene thermometer and providing a reasonable estimate of pre- to syn-eclogite facies P-T. In the case of the Bakersville eclogite samples from North Carolina, the inclusion assemblage yields 10 +/- 2 kbar and 500 +/- 50° C with reaction (1) compared to the peak assemblage at P > 15 +/- 2 kbar and 700 +/- 50° C. These data combined with evidence for a granulite facies overprint indicate a clockwise P-T path for those eclogites. A similar study on the Healdsburg eclogite samples from California yields about 500° C and 12 +/- 1 kbar for the garnet cores, 14 +/- 2 kbar for mantles and 16 +/- 2 kbar for rim-matrix assemblages. The introduction of late glaucophane, epidote and chlorite partially replacing omphacite and garnet implies a retrograde return to the blueschist

  5. Chemical and oxygen isotope zonings in garnet from subducted continental crust record mineral replacement and metasomatism

    Science.gov (United States)

    Vho, Alice; Rubatto, Daniela; Regis, Daniele; Baumgartner, Lukas; Bouvier, Anne-Sophie

    2017-04-01

    Garnet is a key mineral in metamorphic petrology for constraining pressure, temperature and time paths. Garnet can preserve multiple growth stages due to its wide P-T stability field and the relatively slow diffusivity for major and trace elements at sub-solidus temperatures. Pressure-temperature-time-fluid paths of the host rock may be reconstructed by combining metamorphic petrology with microscale trace element and oxygen isotope measurements in garnet. Subduction zones represent relevant geological settings for geochemical investigation of element exchanges during aqueous fluid-rock interactions. The Sesia Zone consists of a complex continental sequence containing a variety of mono-metamorphic and poly-metamorphic lithologies such as metagranitoids, sediments and mafic boudins. The precursor Varisican-Permian amphibolite-facies basement (6-9 kbar 650-850°C; Lardeaux and Spalla, 1991; Robyr et al., 2013) experienced high pressure metamorphism (15-22 kbar 500-550°C; Regis, et al. 2014; Robyr et al., 2013) during Alpine subduction. In different lithologies of the Internal Complex (Eclogitic Micaschist Complex), including metabasites from the Ivozio Complex, Ti-rich metasediments from Val Malone and pre-Alpine Mn-quartzites associated to metagabbros from Cima Bonze, garnet is abundant and shows a variety of complex textures that cannot be reconciled with typical growth zoning, but indicate resorption and replacement processes and possible metasomatism. In-situ, microscale oxygen isotopes analysis of garnet zones was performed by ion microprobe with the SwissSIMS Cameca IMS 1280-HR at University of Lausanne and SHRIMP-SI at the Australian National University. Each sample has a distinct δ18O composition, and the δ18O values show different degrees of variation between domains. Homogeneously low values of element geochemistry and P-T modelling allows reconstructing the major stages of metasomatism, as well as identifying the nature of the fluid interacting with the

  6. Raman spectroscopy of detrital garnet from the (U)HP terrane of eastern Papua New Guinea

    Science.gov (United States)

    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

  7. Gallium modulates osteoclastic bone resorption in vitro without affecting osteoblasts

    Science.gov (United States)

    Verron, Elise; Masson, Martial; Khoshniat, Solmaz; Duplomb, Laurence; Wittrant, Yohann; Baud'huin, Marc; Badran, Zahi; Bujoli, Bruno; Janvier, Pascal; Scimeca, Jean-Claude; Bouler, Jean-Michel; Guicheux, Jérôme

    2010-01-01

    Background and purpose: Gallium (Ga) has been shown to be effective in the treatment of disorders associated with accelerated bone loss, including cancer-related hypercalcemia and Paget's disease. These clinical applications suggest that Ga could reduce bone resorption. However, few studies have studied the effects of Ga on osteoclastic resorption. Here, we have explored the effects of Ga on bone cells in vitro. Experimental approach: In different osteoclastic models [osteoclasts isolated from long bones of neonatal rabbits (RBC), murine RAW 264.7 cells and human CD14-positive cells], we have performed resorption activity tests, staining for tartrate resistant acid phosphatase (TRAP), real-time polymerase chain reaction analysis, viability and apoptotic assays. We also evaluated the effect of Ga on osteoblasts in terms of proliferation, viability and activity by using an osteoblastic cell line (MC3T3-E1) and primary mouse osteoblasts. Key results: Gallium dose-dependently (0–100 µM) inhibited the in vitro resorption activity of RBC and induced a significant decrease in the expression level of transcripts coding for osteoclastic markers in RAW 264.7 cells. Ga also dramatically reduced the formation of TRAP-positive multinucleated cells. Ga down-regulated in a dose-dependant manner the expression of the transcription factor NFATc1. However, Ga did not affect the viability or activity of primary and MC3T3-E1 osteoblasts. Conclusions and implications: Gallium exhibits a dose-dependent anti-osteoclastic effect by reducing in vitro osteoclastic resorption, differentiation and formation without negatively affecting osteoblasts. We provide evidence that this inhibitory mechanism involves down-regulation of NFATc1 expression, a master regulator of RANK-induced osteoclastic differentiation. PMID:20397300

  8. Investigation on the Usage of Some Non-Almandine Garnet Minerals as Abrasive Material in Waterjet Cutting

    OpenAIRE

    Engin, Irfan Celal; Ozkan, Erkan; Kulaksiz, Seyfi

    2011-01-01

    In this study, some non-almandine garnet minerals were investigated in terms of their usage possibilities as alternate abrasive materials in waterjet cutting operations. For this purpose, garnet samples were taken from various deposits and mineralization zones in Turkey. These samples were crushed, ground, screened, concentrated and prepared as having desired particle size distribution, and then used in waterjet cutting practices performed on different materials. Cut surfaces were also invest...

  9. Metamorphic Evolution of Garnet-bearing Epidote-Barroisite Schist from the Meratus Complex in South Kalimantan, Indonesia

    OpenAIRE

    Nugroho Imam Setiawan; Yasuhito Osanai; Nobuhiko Nakano; Tatsuro Adachi; Amril Asy’ari

    2015-01-01

    DOI:10.17014/ijog.2.3.139-156This paper presents metamorphic evolution of metamorphic rocks from the Meratus Complex in South Kalimantan, Indonesia. Eight varieties of metamorphic rocks samples from this location, which are garnet-bearing epidote-barroisite schist, epidote-barroisite schist, glaucophane-quartz schist, garnet-muscovite schist, actinolite-talc schist, epidote schist, muscovite schist, and serpentinite, were investigated in detail its petrological and mineralogical characteristi...

  10. Pulpal thermal responses to an erbium,chromium: YSGG pulsed laser hydrokinetic system.

    Science.gov (United States)

    Rizoiu, I; Kohanghadosh, F; Kimmel, A I; Eversole, L R

    1998-08-01

    Laser systems are known to raise pulpal temperatures when applied to tooth surfaces. Dental biocalcified tissues can be cut with an erbium,chromium:yttrium-scandium-gallium-garnet laser-powered hydrokinetic system. This device is effective for caries removal and cavity preparation in vitro. Pulpal monitoring of temperature changes during hard tissue cutting by a hydrokinetic system have not been reported. This study compared the effects of hydrokinetic system, dry bur, and wet bur tooth cutting on pulpal temperature. In vivo thermocouple intrapulpal measurements were made on cuspid teeth in anesthetized beagle dogs. In vitro measurements were made on extracted human molar teeth preserved in high-salt solution and later rinsed in phosphate-buffered saline (pH 7.4) to simulate in vivo conditions. The hydrokinetic system was compared with conventional air-turbine-powered bur cutting. The hydrokinetic system cuts and bur preparations were randomly made on the buccal surfaces at the cervical one third of the crown and extended until exposure of the pulp was confirmed clinically. Pulpal temperatures associated with the hydrokinetic system either showed no change or decreased by up to 2 degrees C. Wet bur preparations resulted in a 3 degrees to 4 degrees C rise. With dry bur preparations, a 14 degrees C rise in temperature was recorded. Under the conditions of this study, the erbium,chromium:yttrium-scandium-gallium-garnet laser-powered hydrokinetic system, when used for cavity preparation, had no apparent adverse thermal effect as measured in the pulp space.

  11. Laser and electron beam processing of silicon and gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, J.

    1979-10-01

    Laser (photon) and electron beams provide a controlled source of heat by which surface layers of silicon and gallium arsenide can be rapidly melted and cooled with rates exceeding 10/sup 80/C/sec. The melting process has been used to remove displacement damage in ion implanted Si and GaAs, to remove dislocations, loops and precipitates in silicon and to study impurity segregation and solubility limits. The mechanisms associated with various phenomena will be examined. The possible impact of laser and electron beam processing on device technology, particularly with respect to solar cells is discussed.

  12. Anomalous tensoelectric effects in gallium arsenide tunnel diodes

    Energy Technology Data Exchange (ETDEWEB)

    Alekseeva, Z.M.; Vyatkin, A.P.; Krivorotov, N.P.; Shchegol' , A.A.

    1988-02-01

    Anomalous tensoelectric phenomena induced in a tunnel p-n junction by a concentrated load and by hydrostatic compression were studied. The anomalous tensoelectric effects are caused by the action of concentrators of mechanical stresses in the vicinity of the p-n junction, giving rise to local microplastic strain. Under the conditions of hydrostatic compression prolate inclusions approx.100-200 A long play the role of concentrators. Analysis of irreversible changes in the current-voltage characteristics of tunnel p-n junctions made it possible to separate the energy levels of the defects produced with plastic strain of gallium arsenide.

  13. Anomalous tensoelectric effects in gallium arsenide tunnel diodes

    Science.gov (United States)

    Alekseeva, Z. M.; Vyatkin, A. P.; Krivorotov, N. P.; Shchegol', A. A.

    1987-08-01

    Anomalous tensoelectric phenomena induced in a tunnel p-n junction by a concentrated load and by hydrostatic compression were studied. The anomalous tensoelectric effects are caused by the action of concentrators of mechanical stresses in the vicinity of the p-n junction, giving rise to local microplastic strain. Under the conditions of hydrostatic compression prolate inclusions ∿100 200 å long play the role of concentrators. Analysis of irreversible changes in the current-voltage characteristics of tunnel p-n junctions made it possible to separate the energy levels of the defects produced with plastic strain of gallium arsenide.

  14. Electronic transport properties of graphene doped by gallium

    Science.gov (United States)

    Mach, J.; Procházka, P.; Bartošík, M.; Nezval, D.; Piastek, J.; Hulva, J.; Švarc, V.; Konečný, M.; Kormoš, L.; Šikola, T.

    2017-10-01

    In this work we present the effect of low dose gallium (Ga) deposition (graphene grown by chemical vapor deposition. In situ graphene transport measurements performed with a graphene field-effect transistor structure show that at low Ga coverages a graphene layer tends to be strongly n-doped with an efficiency of 0.64 electrons per one Ga atom, while the further deposition and Ga cluster formation results in removing electrons from graphene (less n-doping). The experimental results are supported by the density functional theory calculations and explained as a consequence of distinct interaction between graphene and Ga atoms in case of individual atoms, layers, or clusters.

  15. A gallium phosphide high-temperature bipolar junction transistor

    Science.gov (United States)

    Zipperian, T. E.; Dawson, L. R.; Chaffin, R. J.

    1981-01-01

    Preliminary results are reported on the development of a high temperature (350 C) gallium phosphide bipolar junction transistor (BJT) for geothermal and other energy applications. This four-layer p(+)n(-)pp(+) structure was formed 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 the lightly doped base. By appropriate choice of electrodes, the device may also be driven as an n-channel junction field-effect transistor. The initial design suffers from a series resistance problem which limits the transistor's usefulness at high temperatures.

  16. Gallium Phosphide as a material for visible and infrared optics

    Directory of Open Access Journals (Sweden)

    Václavík J.

    2013-05-01

    Full Text Available Gallium phosphide is interesting material for optical system working in both visible and MWIR or LWIR spectral ranges. Number of a material available for these applications is limited. They are typically salts, fluorides or sulphides and usually exhibit unfavorable properties like brittleness; softness; solubility in water and small chemical resistance. Although GaP has do not offer best optical parameters excels over most other material in mechanical and chemical resistance. The article describes its most important characteristics and outlines some applications where GaP should prove useful.

  17. Lasing action in gallium nitride quasicrystal nanorod arrays.

    Science.gov (United States)

    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.

  18. Gallium nitride electrodes for membrane-based electrochemical biosensors.

    Science.gov (United States)

    Schubert, T; Steinhoff, G; von Ribbeck, H-G; Stutzmannn, M; Eickhoff, M; Tanaka, M

    2009-10-01

    We report on the deposition of planar lipid bilayers (supported membranes) on gallium nitride (GaN) electrodes for potential applications as membrane-based biosensors. The kinetics of the lipid membrane formation upon vesicle fusion were monitored by simultaneous measurements of resistance and capacitance of the membrane using AC impedance spectroscopy in the frequency range between 50 mHz and 50 kHz. We could identify a two-step process of membrane spreading and self-healing. Despite its relatively low resistance, the membrane can be modeled by a parallel combination of an ideal resistor and capacitor, indicating that the membrane efficiently blocks the diffusion of ions.

  19. Testing of gallium arsenide solar cells on the CRRES vehicle

    Science.gov (United States)

    Trumble, T. M.

    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. Hybrid yttrium iron garnet-ferromagnet structures for spin-wave devices

    Energy Technology Data Exchange (ETDEWEB)

    Papp, A., E-mail: apapp@nd.edu [Center for Nano Science and Technology and Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Pázmány Péter Catholic University, Faculty of Information Technology, Budapest 1088 (Hungary); Porod, W., E-mail: porod@nd.edu; Csaba, G., E-mail: gcsaba@nd.edu [Center for Nano Science and Technology and Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2015-05-07

    We study coupled ferromagnetic layers, which could facilitate low loss, sub 100 nm wavelength spin-wave propagation and manipulation. One of the layers is a low-loss garnet film (such as yttrium iron garnet (YIG)) that enables long-distance, coherent spin-wave propagation. The other layer is made of metal-based (Permalloy, Co, and CoFe) magnetoelectronic structures that can be used to generate, manipulate, and detect the spin waves. Using micromagnetic simulations, we analyze the interactions between the spin waves in the YIG and the metallic nanomagnet structures and demonstrate the components of a scalable spin-wave based signal processing device. We argue that such hybrid-metallic ferromagnet structures can be the basis of potentially high-performance, ultra low-power computing devices.

  1. Ce{sup 3+}-doped crystalline garnet films - scintillation characterization using {alpha}-particle excitation

    Energy Technology Data Exchange (ETDEWEB)

    Mares, Jiri A., E-mail: amares@fzu.c [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic); Prusa, Petr [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic); Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, Brehova 7, 115 19 Prague 1 (Czech Republic); Nikl, Martin; Nitsch, Karel; Beitlerova, Alena [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic); Kucera, Miroslav; Hanus, Martin [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Zorenko, Yurij [Laboratory of Optoelectronic Materials, Department of Electronics, Ivan Franko National University of Lviv, 107 Gen. Tarnavskogo Str. (Ukraine)

    2010-03-15

    Scintillating properties of Ce{sup 3+}-doped (Lu,Y) aluminum garnet single crystalline films (SCF) were investigated. Thin SCF films of thickness between 1 and 30 {mu}m were grown by a liquid phase epitaxy (LPE) method in various fluxes. The {alpha}-particle excitation (mainly 5.4857 MeV line of {sup 241}Am) of pulse height spectra is used to measure scintillation response of SCF, especially peak of those {alpha}-rays which are totally absorbed in the films. Detailed studies and evaluation of scintillation measurements of large sets of Ce{sup 3+}-doped SCF (Lu,Y) aluminum garnets showed that at present time (i) YAG:Ce SCF have comparable scintillation properties as YAG:Ce single crystals, especially their N{sub phels} photoelectron yields are the same while (ii) scintillation properties of LuAG:Ce SCF do not reach those of LuAG:Ce single crystal.

  2. Discovery of natural MgSiO3 tetragonal garnet in a shocked chondritic meteorite.

    Science.gov (United States)

    Tomioka, Naotaka; Miyahara, Masaaki; Ito, Motoo

    2016-03-01

    MgSiO3 tetragonal garnet, which is the last of the missing phases of experimentally predicted high-pressure polymorphs of pyroxene, has been discovered in a shocked meteorite. The garnet is formed from low-Ca pyroxene in the host rock through a solid-state transformation at 17 to 20 GPa and 1900° to 2000°C. On the basis of the degree of cation ordering in its crystal structure, which can be deduced from electron diffraction intensities, the cooling rate of the shock-induced melt veins from ~2000°C was estimated to be higher than 10(3)°C/s. This cooling rate sets the upper bound for the shock-temperature increase in the bulk meteorite at ~900°C.

  3. Mechanical properties and microstructure of stir casted Al/B{sub 4}C/garnet composites

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rathinam Ashok [Chendhuran College of Engineering and Technology, Tamil Nadu (India). Mechanical Engineering Dept.; Sait, Abdullah Naveen [Chendhuran College of Engineering and Technology, Tamil Nadu (India); Subramanian, Karuppazhi [Government College of Engineering, Tamil Nadu (India). Dept. of Mechanical Engineering

    2017-05-01

    Aluminum based metal matrix composites are one of the advanced engineering materials that have been developed for low weight and high strength applications in automotive industries due to high specific strength and good wear resistance. In this context, aluminum alloy boron carbide and garnet composites were fabricated by the stir casting process. The microstructural examination was done by using a scanning electron microscope to assess the distribution of particulates in the aluminum matrix. The composites were characterized by hardness and tensile tests. The wear behavior of the composites was analyzed with the help of a pin-on-disc wear test. By increasing the amount of garnet in the composite, it has been observed that the tensile strength and hardness increase. The wear test analysis proved that the addition of reinforcements reduces the wear rate behavior of composite.

  4. Compositional trends among Kaapvaal Craton garnet peridotite xenoliths and their effects on seismic velocity and density

    DEFF Research Database (Denmark)

    Schutt, Derek; Lesher, Charles

    2010-01-01

    We examine the modes and compositions of garnet-bearing peridotite xenoliths from the Kaapvaal Craton to quantify factors governing density and seismic velocity variations within metasomatically altered cratonic mantle. Three distinct compositional trends are resolved by principal component...... analysis. The first reflects differences in residue composition resulting from partial melting. The second is associated with orthopyroxene (opx) enrichment, possibly due to silica addition by subduction zone fluids in the source region of the xenoliths. The third principal component reflects garnet...... and clinopyroxene enrichment possibly as a consequence of melt infiltration. More than half of the mineral mode variance among Kaapvaal Craton xenoliths can be accounted for by opx enrichment. Melt depletion effects can account for as much as 30% of the variance, while less than 20% of the variance is associated...

  5. Radiation tests on erbium-doped garnet crystals for spaceborne CH4-Lidar applications

    Science.gov (United States)

    Meissner, Ansgar; Kreitler, Martin; Cubera, Miroslaw; Kucirek, Philipp; Gronloh, Bastian; Esser, Dominik; Höfer, Marco; Hoffmann, Hans-Dieter

    2015-02-01

    A test campaign for assessing the radiation hardness of different Erbium-doped garnet crystals including Er:YAG and a compositionally tuned Er:YAG/Er:LuAG mixed garnet is reported. Tests with proton and gamma radiation have been performed with parameters mimicking a 3-year low-earth-orbit satellite mission like MERLIN or ADM-Aeolus. For each test sample broadband transmission spectra in the wavelength range of 500 nm - 1700 nm and characteristic laser curves from a test laser oscillator have been measured. Radiation-induced losses have been calculated from the obtained data. The results indicate that gamma radiation is the dominant loss source with about 0.5 %/cm radiation-induced losses for the nominal dose of the chosen mission scenario.

  6. Trace element mapping by LA-ICP-MS: assessing geochemical mobility in garnet

    Science.gov (United States)

    Raimondo, Tom; Payne, Justin; Wade, Benjamin; Lanari, Pierre; Clark, Chris; Hand, Martin

    2017-04-01

    A persistent problem in the study of garnet geochemistry is that the consideration of major elements alone excludes a wealth of information preserved by trace elements, particularly the rare-earth elements (REEs). This is despite the fact that trace elements are generally less vulnerable to diffusive resetting, and are sensitive to a broader spectrum of geochemical interactions involving the entire mineral assemblage, including the growth and/or dissolution of accessory minerals. We outline a technique for the routine acquisition of high-resolution 2D trace element maps by LA-ICP-MS, and introduce an extension of the software package XMapTools for rapid processing of LA-ICP-MS data to visualise and interpret compositional zoning patterns. These methods form the basis for investigating the mechanisms controlling geochemical mobility in garnet, which are argued to be largely dependent on the interplay between element fractionation, mineral reactions and partitioning, and the length scales of intergranular transport. Samples from the Peaked Hill shear zone, Reynolds Range, central Australia, exhibit contrasting trace element distributions that can be linked to a detailed sequence of growth and dissolution events. Trace element mapping is thus employed to place garnet evolution in a specific paragenetic context and derive absolute age information by integration with existing U-Pb monazite and Sm-Nd garnet geochronology. Ultimately, the remarkable preservation of original growth zoning and its subtle modification by subsequent re-equilibration is used to `see through' multiple superimposed events, thereby revealing a previously obscure petrological and temporal record of metamorphism, metasomatism, and deformation.

  7. Magnetic moments in a gadolinium iron garnet studied by soft-X-ray magnetic circular dichroism

    NARCIS (Netherlands)

    Rudolf, P.; Sette, F.; Tjeng, L.H.; Meigs, G.; Chen, C.T.

    1992-01-01

    The magnetic moments of Gd and Fe in gadolinium iron garnet (Gd3Fe5O12) were probed at 77 and 300 K by soft-X-ray magnetic circular dichroism (SXMCD) measurements at the GdMa4,5 and at the FeL2,3 absorption edges. The SXMCD signal at each edge allows one to independently determine the magnetic

  8. Skarn formation and trace elements in garnet and associated minerals from Zhibula copper deposit, Gangdese Belt, southern Tibet

    Science.gov (United States)

    Xu, Jing; Ciobanu, Cristiana L.; Cook, Nigel J.; Zheng, Youye; Sun, Xiang; Wade, Benjamin P.

    2016-10-01

    Trace element concentrations in garnet and associated minerals from the mid-Miocene Zhibula Cu skarn, Gangdese Belt, Tibet reflect a diversity of local environments, evolving fluid parameters and partitioning with coexisting minerals. Exoskarn occurs as massive but narrow intervals within a Lower Jurassic volcano-sedimentary sequence containing limestone, the main skarn protolith. Endoskarn is present at the contact with mid-Miocene granodiorite dikes. Prograde skarn associations are garnet-dominant but also include diopside-dominant pyroxene in variable amounts. Garnet compositions in exoskarn change from andradite (And)- to grossular (Gr)-dominant from the massive intervals to bands/lenses within marble/tuff, but not in endoskarn. In both cases however, associations at the protolith contact include anorthite and wollastonite, both indicative of skarnoid or distal (relative to fluid source) skarn formation. Exoskarns also contain vesuvianite. Retrograde clinozoisite, actinolite and chlorite replace pre-existing skarn minerals. Garnet displays brecciation and replacement by Al-richer garnet. Depending on partitioning among coexisting minerals, chondrite-normalised REY (REE + Y) fractionation trends for garnet depict endo- to exoskarn diversity, the dominance of And- vs. Gr-rich garnet (in turn related to proximal-to-distal relationship to fluid source), as well as prograde-to-retrograde evolution in the same sample. A strong variation in Eu-anomaly, from positive to negative, in And-dominant garnet can be correlated with variation in salinity of ore-forming fluids, concordant with published fluid inclusion data. Trends depicted by And- and Gr-dominant garnets are consistent with published data from skarns elsewhere, in which the dominant substitution mechanism for REY is YAG-type. Zhibula garnets are enriched in a range of trace elements less commonly reported, including W, Sn, and As, but also Mo (as high as 730 ppm), an element seldom analysed for in silicates

  9. Formation of metamorphic and metamorphosed garnets in the low-T/UHP metagranite during continental collision in the Dabie orogen

    Science.gov (United States)

    Xia, Qiong-Xia; Zheng, Yong-Fei; Lu, Xiao-Nan; Hu, Zhaochu; Xu, Haijun

    2012-04-01

    A combined study of major and trace elements in garnet was carried out for low-T/UHP metagranite in the Dabie orogen. The results show different fashions of element zoning in the garnet, suggesting occurrence of both metamorphic and metamorphosed garnets. Three generations of garnet growth are distinguished on the basis of the assumption that Ca contents, Mn contents and Fe/Mg ratios of garnet in metagranites are a function of pressure and temperature. The first generation of garnet (Grt-I) occurs in the core of a skeletal garnet, showing homogeneously low XGrs values and Fe/Mg ratios but high XSps values. This implies that the core garnet grew at the highest temperature but the lowest pressure, representing a metamorphosed residue of magmatic garnet in protolith granite. The second generation of garnet (Grt-II) occurs in the mantles and cores of many garnet grains, exhibiting increased XGrs values but decreased Fe/Mg ratios. This is ascribed to a continuous increase in temperature and pressure till the peak pressure, corresponding to metamorphic growth (or overgrowth) during the prograde subduction. The third generation of garnet (Grt-III) occurs in the rims of all garnet grains, displaying decreased XGrs values and Fe/Mg ratios in response to a pressure decrease but a temperature increase till the peak temperature. These rims overgrew subsequent to the peak pressure with continuous heating during the initial exhumation. Grt-I shows steep MREE-HREE patterns and profoundly negative Eu anoalies, consistent with growth from granitic melt. This kind of metamorphosed garnet from protolith granite has still preserved very high contents of many trace elements (such as REE, Rb, Ba, Sr, Pb, Th, U, Nb and Ta) despite the low-T/UHP metamorphism. Grt-II and Grt-III in one sample exhibit steep MREE-HREE patterns, with a continuous decrease in REE contents. This suggests their growth from the almost same matrix of mineral assemblages (plagioclase + K-feldspar + muscovite

  10. Site distribution in heavily Sc3+-, Zr4+-, and Hf4+- substituted yttrium iron garnet

    Science.gov (United States)

    Balestrino, G.; Geller, S.

    1983-05-01

    Mössbauer spectra of yttrium iron garnet containing large amounts of Sc3+, Zr4+, and Hf4+ substituted for Fe3+ ions (the last two with electrostatic compensation by Ca2+ ions) confirm the conclusions deduced from 0-K spontaneous magnetization that the Zr4+ and Hf4+ ions prefer octahedral sites exclusively. Very small amounts of Sc3+ ions enter tetrahedral sites: For a total of one Sc3+ ion per formula unit, 0.03 is tetrahedral; for a total of 1.5 Sc3+ ions per formula unit, 0.09 is tetrahedral. These results imply that in the region of the ferrimagnetic ground state, i.e., to 0.72 Sc3+ ion per formula unit, at most 0.02 is tetrahedral, but it could be that there is none because of the coincidence of the 0-K dependence of the spontaneous magnetization on the composition of the Zr4+- and Sc3+-substituted yttrium iron garnets in that region. Thus the model given by Geller et al. for the magnetic behavior of substituted iron garnets is corroborated by these results.

  11. Raman mapping of coesite inclusions in garnet from the Kokchetav Massif (Northern Kazakhstan).

    Science.gov (United States)

    Korsakov, Andrey V; Hutsebaut, Didier; Theunissen, Karel; Vandenabeele, Peter; Stepanov, Alexander S

    2007-12-15

    Coesite inclusions occur in a wide range of lithologies and coesite is therefore a powerful ultrahigh-pressure (UHP) indicator. The transformation of coesite to quartz is evidenced by three optically well identifiable characteristics (e.g. palisade textures, radial crack patterns, polycrystalline quartz pseudomorphs). Under overpressure monomineralic coesite (on an optical basis), lacking the above transformation characteristics may survive. Raman micro-spectroscopy was applied on monomineralic coesite inclusions in garnet porphyroblasts from diamond-bearing garnet-clinozoisite-biotite gneisses of the Barchi-Kol area (Kokchetav Massif, Northern Kazakhstan). These coesite inclusions are euhedral and display a characteristic anisotropic hallo. However, Raman maps and separate spectra of these inclusions display shifted bands for coesite and quartz. Microscopically undetectable, quartz shows on the Raman map as a thin shell around coesite inclusion. Shift of the main coesite band allows to estimate their overpressure: coesite inclusions record 0-2.4 GPa in garnet and zircon. The quartz shell remains under lower pressure 0-1.6 GPa. The possible application of coesite and quartz Raman geobarometers for UHP metamorphic rocks is discussed.

  12. Atomic Layer Deposition of the Solid Electrolyte Garnet Li7La3Zr2O12

    Energy Technology Data Exchange (ETDEWEB)

    Kazyak, Eric; Chen, Kuan-Hung; Wood, Kevin N.; Davis, Andrew L.; Thompson, Travis; Bielinski, Ashley R.; Sanchez, Adrian; Wang, Xiang; Wang, Chongmin; Sakamoto, Jeff S.; Dasgupta, Neil P.

    2017-04-25

    Lithium solid electrolytes are a promising platform for achieving high energy density, long-lasting, and safe rechargeable batteries, which could have widespread societal impact. In particular, the ceramic oxide garnet Li7La3Zr2O12 (LLZO) has been shown to be a promising electrolyte due to its stability and high ionic conductivity. Two major challenges for commercialization are manufacturing of thin layers and creating stable, low-impedance, interfaces with both anode and cathode materials. Atomic Layer Deposition (ALD) has recently been shown as a potential method for depositing both solid electrolytes and interfacial layers to improve the stability and performance at electrode-electrolyte interfaces in battery systems. Herein we present the first reported ALD process for LLZO, demonstrating the ability to tune composition within the amorphous film and anneal to achieve the desired cubic garnet phase. Formation of the cubic phase was observed at temperatures as low as 555°C, significantly lower than is required for bulk processing. Additionally, challenges associated with achieving a dense garnet phase due to substrate reactivity, morphology changes and Li loss under the necessary high temperature annealing are quantified via in situ synchrotron diffraction.

  13. Composition engineering of single crystalline films based on the multicomponent garnet compounds

    Science.gov (United States)

    Zorenko, Yuriy; Gorbenko, Vitalii; Zorenko, Tetiana; Paprocki, Kazimierz; Bilski, Paweł; Twardak, Anna; Voznyak, Taras; Sidletskiy, Oleg; Gerasimov, Yaroslav; Gryniov, Boris; Fedorov, Alexandr

    2016-11-01

    The paper demonstrates our last achievement in development of the novel scintillating screens based on single crystalline films (SCF) of Ce doped multicomponent garnets using the Liquid Phase Epitaxy (LPE) method. We report in this work the optimized content and excellent scintillation properties of SCF of Lu3-xGdxAl5-yGayO12, Lu3-xTbxAl5-yGayO12 and TbxGdxAl5-yGayO12 garnet compounds grown by the LPE method from PbOsbnd B2O3 based melt-solution onto Gd3Al2.5Ga2.5O12 and YAG substrates. We also show that the Tb1.5Gd1.5Al2.5Ga2.5O12:Ce SCF possess the highest light yield (LY) in comparison with all ever grown garnet SCF scintillators. Namely, the LY of these SCF exceeds by 3.8 and 1.85 times the LY values of the best samples of YAG:Ce and LuAG:Ce SCF scintillators, respectively. The SCF samples of the mentioned compounds show low thermoluminescence in the above room temperature range and relatively fast scintillation decay time t1/e in the 180-200 ns range.

  14. Gd-Sc-based mixed-metal nitride cluster fullerenes: mutual influence of the cage and cluster size and the role of scandium in the electronic structure.

    Science.gov (United States)

    Svitova, Anna L; Popov, Alexey A; Dunsch, Lothar

    2013-03-18

    The influence of the cage as well as of the cluster size has been studied in Gd-Sc nitride cluster fullerenes, which have been synthesized and isolated for these studies. A series of carbon cages ranging from C78 to C88 have been synthesized, isolated, and characterized in detail using absorption and vibrational spectroscopy as well as electrochemistry and density functional theory calculations. Gd-Sc mixed-metal cluster fullerenes in carbon cages different from C80 were described for the first time. A review of their structures, properties, and stability is given. The synthesis was performed with melamine as an effective solid source of nitrogen, providing high fullerene yield and suppressing empty fullerene formation. Substitution of gadolinium by scandium imposes a noticeable influence on the electronic structure of nitride cluster fullerenes as revealed by electrochemical, spectroscopic, and computational methods.

  15. Clinical, morphological, and ultrastructural aspects with the use of Er:YAG and Er,Cr:YSGG lasers in restorative dentistry.

    Science.gov (United States)

    Iaria, Giuseppe

    2008-01-01

    The Er:YAG laser has an active medium of Yttrium-Aluminium-Garnet doped with Erbium ions and emits free-running pulsed laser energy at a wavelength of 2940 nm. The Er,Cr:YSGG laser has an active medium of Yttrium-Scandium-Gallium-Garnet doped with Erbium and Chromium ions and emits free-running pulsed laser energy at a wavelength of 2780 nm. These wavelengths have a high absorption in water, which makes their application appropriate for ablating oral soft tissue as well as dental hard tissue. This article examines the principles of use for the Er:YAG and Er,Cr:YSGG lasers in clinical restorative dentistry and reviews the literature regarding different aspects of the use of laser energy on hard tissues.

  16. Technologic advances in endodontics.

    Science.gov (United States)

    Mortman, Rory E

    2011-07-01

    This article addresses technologic advances in endodontics pertaining to new and emerging technology. Cone-beam computed tomography and optical occurrence tomography are 2 new imaging technologies that can assist the practitioner in the diagnosis of pulpal disease. The self-adjusting file and the Apexum device can be used for instrumentation and bulk debridement of an apical lesion, respectively. Neodymium:yttrium-aluminum-garnet laser, erbium:chromium:yttrium-scandium-gallium-garnet laser, EndoActivator, EndoVac, and light-activated disinfection may assist the practitioner in cleaning the root canal system. Computed tomography-guided surgery shows promise in making endodontic surgery easier, as does mineral trioxide aggregate cement for regenerative endodontic procedures. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Laser systems for ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Paasch, Uwe; Haedersdal, Merete

    2011-01-01

    Ablative fractional resurfacing (AFR) creates microscopic vertical ablated channels that are surrounded by a thin layer of coagulated tissue, constituting the microscopic treatment zones (MTZs). AFR induces epidermal and dermal remodeling, which raises new possibilities for the treatment of a var......Ablative fractional resurfacing (AFR) creates microscopic vertical ablated channels that are surrounded by a thin layer of coagulated tissue, constituting the microscopic treatment zones (MTZs). AFR induces epidermal and dermal remodeling, which raises new possibilities for the treatment...... ablative laser systems. Fractionated CO(2) (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities...

  18. The impact of gallium content on degradation, bioactivity, and antibacterial potency of zinc borate bioactive glass.

    Science.gov (United States)

    Rahimnejad Yazdi, Alireza; Torkan, Lawrence; Stone, Wendy; Towler, Mark R

    2017-02-02

    Zinc borate glasses with increasing gallium content (0, 2.5, 5, 10, and 15 Wt % Ga) were synthesized and their degradation, bioactivity in simulated body fluid (SBF), and antibacterial properties were investigated. ICP measurements showed that increased gallium content in the glass resulted in increased gallium ion release and decreased release of other ions. Degradability declined with the addition of gallium, indicating the formation of more symmetric BO3 units with three bridging oxygens and asymmetric BO3 units with two bridging oxygens in the glass network as the gallium content in the series increased. The formation of amorphous CaP on the glass surface after 24 h of incubation in SBF was confirmed by SEM, XRD, and FTIR analyses. Finally, antibacterial evaluation of the glasses using the agar disc-diffusion method demonstrated that the addition of gallium increased the antibacterial potency of the glasses against P. aeruginosa (Gram-negative) while decreasing it against S. epidermidis (Gram-positive); considering the ion release trends, this indicates that the gallium ion is responsible for the glasses' antibacterial behavior against P. aeruginosa while the zinc ion controls the antibacterial activity against S. epidermidis. The statistical significance of the observed trends in the measurements were confirmed by applying the Kruskal-Wallis H Test. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  19. Mechanisms of thermal induced gallium removal (TIGR) from plutonium dioxide. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    DeMuth, S.F.

    1998-08-07

    This study was initiated in order to determine the advantages of using a mixed-bed rather than a fixed-bed reactor (i.e. furnace) for separation of gallium from PuO{sub 2} by the Thermal Induced Gallium Removal (TIGR) process. The TIGR process is based upon vaporization of gallium suboxide (Ga{sub 2}O). from essentially nonvolatile PuO{sub 2}. The gallium suboxide is formed by passing a reducing gas (i.e. hydrogen) over the PuO{sub 2} particles. Several mechanisms are involved in the reduction and convective vaporization of the gallium suboxide. If the mass transfer of the gallium suboxide across the solid to gas interface significantly affects the processing time, it may be advantageous to use a mixed-bed reactor rather than a fixed-bed reactor. However, due to the difficulty of handling PuO{sub 2} powder, a mixed-bed reactor should be used only if significant advantages can be demonstrated. Based on available data, the results of this study provide strong evidence that a mixed-bed reactor (i.e. furnace) would provide little advantage over a fixed-bed reactor. This is due to the conclusion that the mechanism of internal gallium diffusion within the particle has the predominant affect on the processing time. This is an important conclusion since the use of a mixed-bed would require development of more complex hardware than for a fixed-bed.

  20. Byproduct Metal Availability Constrained by Dynamics of Carrier Metal Cycle: The Gallium-Aluminum Example.

    Science.gov (United States)

    Løvik, Amund N; Restrepo, Eliette; Müller, Daniel B

    2016-08-16

    Future availability of byproduct metals is not limited by geological stocks, but by the rate of primary production of their carrier metals, which in turn depends on the development of their in-use stocks, the product lifetimes, and the recycling rates. This linkage, while recognized conceptually in past studies, has not been adequately taken into account in resource availability estimates. Here, we determine the global supply potential for gallium up to 2050 based on scenarios for the global aluminum cycle, and compare it with scenarios for gallium demand derived from a dynamic model of the gallium cycle. We found that the gallium supply potential is heavily influenced by the development of the in-use stocks and recycling rates of aluminum. With current applications, a shortage of gallium is unlikely by 2050. However, the gallium industry may need to introduce ambitious recycling- and material efficiency strategies to meet its demand. If in-use stocks of aluminum saturate or decline, a shift to other gallium sources such as zinc or coal fly ash may be required.

  1. Crystallographic alignment of high-density gallium nitride nanowire arrays.

    Science.gov (United States)

    Kuykendall, Tevye; Pauzauskie, Peter J; Zhang, Yanfeng; Goldberger, Joshua; Sirbuly, Donald; Denlinger, Jonathan; Yang, Peidong

    2004-08-01

    Single-crystalline, one-dimensional semiconductor nanostructures are considered to be one of the critical building blocks for nanoscale optoelectronics. Elucidation of the vapour-liquid-solid growth mechanism has already enabled precise control over nanowire position and size, yet to date, no reports have demonstrated the ability to choose from different crystallographic growth directions of a nanowire array. Control over the nanowire growth direction is extremely desirable, in that anisotropic parameters such as thermal and electrical conductivity, index of refraction, piezoelectric polarization, and bandgap may be used to tune the physical properties of nanowires made from a given material. Here we demonstrate the use of metal-organic chemical vapour deposition (MOCVD) and appropriate substrate selection to control the crystallographic growth directions of high-density arrays of gallium nitride nanowires with distinct geometric and physical properties. Epitaxial growth of wurtzite gallium nitride on (100) gamma-LiAlO(2) and (111) MgO single-crystal substrates resulted in the selective growth of nanowires in the orthogonal [1\\[Evec]0] and [001] directions, exhibiting triangular and hexagonal cross-sections and drastically different optical emission. The MOCVD process is entirely compatible with the current GaN thin-film technology, which would lead to easy scale-up and device integration.

  2. Macroscopic diffusion models for precipitation in crystalline gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Kimmerle, Sven-Joachim Wolfgang

    2009-09-21

    Based on a thermodynamically consistent model for precipitation in gallium arsenide crystals including surface tension and bulk stresses by Dreyer and Duderstadt, we propose two different mathematical models to describe the size evolution of liquid droplets in a crystalline solid. The first model treats the diffusion-controlled regime of interface motion, while the second model is concerned with the interface-controlled regime of interface motion. Our models take care of conservation of mass and substance. These models generalise the well-known Mullins- Sekerka model for Ostwald ripening. We concentrate on arsenic-rich liquid spherical droplets in a gallium arsenide crystal. Droplets can shrink or grow with time but the centres of droplets remain fixed. The liquid is assumed to be homogeneous in space. Due to different scales for typical distances between droplets and typical radii of liquid droplets we can derive formally so-called mean field models. For a model in the diffusion-controlled regime we prove this limit by homogenisation techniques under plausible assumptions. These mean field models generalise the Lifshitz-Slyozov-Wagner model, which can be derived from the Mullins-Sekerka model rigorously, and is well understood. Mean field models capture the main properties of our system and are well adapted for numerics and further analysis. We determine possible equilibria and discuss their stability. Numerical evidence suggests in which case which one of the two regimes might be appropriate to the experimental situation. (orig.)

  3. Role of ferritin in the intracellular distribution of gallium 67

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, K.; Kawaguchi, H.; Shimizu, K.; Orii, H.

    1984-05-01

    The binding of gallium 67 or iron 59 to ferritin in vitro was investigated using equilibrium dialysis. Gallium 67 did not bind to apo-ferritin until the protein was transformed into ferritin in the presence of iron citrate. Apotransferrin inhibited the binding of /sup 67/Ga to ferritin, especially in the presence of sodium bicarbonate and citrate, thus indicating that /sup 67/Ga has not gained access to ferritin from its complex with transferrin. Similar inhibition was observed for ferritin-/sup 59/Fe. The release of /sup 59/Fe from its transferrin complex was enhanced by ATP, citrate, or ascorbic acid, while these reagents did not stimulate the dissociation of /sup 67/Ga from its transferrin complex. On the other hand, /sup 67/Ga injected intravenously in vivo was not found in the ferritin fractions of rate liver, kidney, and tumor. The difference between experimental results in vivo and in vitro supports the hypothesis that /sup 67/Ga in the cytoplasm is not labile enough to be found to ferritin. We have indicated a significant role of ferritin in distinguishing between /sup 67/Ga and /sup 59/Fe in the cell, and provided some clues to interpret the chemical forms of /sup 67/Ga in the cytoplasm.

  4. Gallium nanoparticles colloids synthesis for UV bio-optical sensors

    Science.gov (United States)

    Nucciarelli, Flavio; Bravo, Iria; Vázquez, Luis; Lorenzo, Encarnación; Pau, Jose Luis

    2017-05-01

    A new method for the synthesis of colloidal gallium nanoparticles (Ga NPs) based on the thermal evaporation of Ga on an expendable aluminum zinc oxide (AZO) layer is presented here. The growth of AZO layers was investigated on different substrates at room temperature and 300 °C. By means of physical evaporation process, nanoparticles were deposited with a distribution ranging from 10 nm to 80 nm in diameter. A study of their endurance in acidic environment was carried out in order to assure the NPs shape and size stability during the etching process. Smaller particles start to disappear between 1h and 2h immersion time in a pH=1 solution, while bigger particles reduce their dimension. The NPs were dispersed in tetrahydrofuran (THF) organic solvent and optically characterized, showing strong UV absorption with a band centered at 280 nm. The colloids size distribution of as-evaporated samples was compared with the distribution obtained in droplets of the solution after drop-casting. By Dipole Discrete Approximation simulations, a close relationship between the UV absorption and the NPs with diameter smaller than 40 nm was found. Because of the gallium oxide (Ga1-xOx) outer shell that surrounds the Ga NPs, an enhancement of their hydrophobicity occurs. Hence, the low agglomeration state between NPs in tetrahydrofuran allows to obtain narrow absorption band in the optical spectrum.

  5. Copper scandium zirconium phosphate

    DEFF Research Database (Denmark)

    Bond, Andrew David; Warner, Terence Edwin

    2013-01-01

    components. The [Sc(III)Zr(IV)(PO(4))(3)](2-) framework is composed of corner-sharing Sc/ZrO(6) octahedra and PO(4) tetrahedra. The Sc and Zr atoms are disordered on one atomic site on a crystallographic threefold axis. The P atom of the phosphate group lies on a crystallographic twofold axis. Nonframework...

  6. High-surface Thermally Stable Mesoporous Gallium Phosphates Constituted by Nanoparticles as Primary Building Blocks

    Energy Technology Data Exchange (ETDEWEB)

    V Parvulescu; V Parvulescu; D Ciuparu; C Hardacre; H Garcia

    2011-12-31

    In constant, search for micro/mesoporous materials, gallium phosphates, have attracted continued interest due to the large pore size reported for some of these solids in comparison with analogous aluminum phosphates. However up to now, the porosity of gallium phosphates collapsed upon template removal or exposure to the ambient moisture. In the present work, we describe high-surface thermally stable mesoporous gallium phosphates synthesized from gallium propoxide and PCl{sub 3} and different templating agents such as amines (dipropylamine, piperidine and aminopiperidine) and quaternary ammonium salts (C{sub 16}H{sub 33}(CH{sub 3})3NBr and C{sub 16}PyCl). These highly reactive precursors have so far not been used as gallium and phosphate sources for the synthesis of gallophosphates. Conceptually, our present synthetic procedure is based on the fast formation of gallium phosphate nanoparticles via the reaction of gallium propoxide with PCl{sub 3} and subsequent construction of the porous material with nanoparticles as building blocks. The organization of the gallophosphate nanoparticles in stable porous structures is effected by the templates. Different experimental procedures varying the molar composition of the sol-gel, pH and the pretreatment of gallium precursor were assayed, most of them leading to satisfactory materials in terms of thermal stability and porosity. In this way, a series of gallium phosphates with surface are above 200 m{sup 2} g{sup -1}, and narrow pore size from 3 to 6 nm and remarkable thermal stability (up to 550 C) have been prepared. In some cases, the structure tends to show some periodicity and regularity as determined by XRD. The remarkable stability has allowed us to test the catalytic activity of gallophosphates for the aerobic oxidation of alkylaromatics with notable good results. Our report reopens the interest for gallophosphates in heterogeneous catalysis.

  7. The Effect of Gallium Nitrate on Arresting Blood Flow from a Wound

    Directory of Open Access Journals (Sweden)

    Paul H. Goodley

    2011-01-01

    Full Text Available A novel application of gallium nitrate, hitherto unreported, in reducing bleeding time from an open wound is presented. Experiments performed using simple punctures in the forearm demonstrated a very substantial reduction in bleeding time when a solution of gallium nitrate was applied relative to a control. This outcome was shown to be unaffected by the anticoagulant properties of warfarin. The mechanism for such action of gallium nitrate is unknown and merits further investigation, as do the possibilities for such an application to improve both civilian and defense trauma treatment modalities.

  8. Toward garnet electrolyte-based Li metal batteries: An ultrathin, highly effective, artificial solid-state electrolyte/metallic Li interface.

    Science.gov (United States)

    Fu, Kun Kelvin; Gong, Yunhui; Liu, Boyang; Zhu, Yizhou; Xu, Shaomao; Yao, Yonggang; Luo, Wei; Wang, Chengwei; Lacey, Steven D; Dai, Jiaqi; Chen, Yanan; Mo, Yifei; Wachsman, Eric; Hu, Liangbing

    2017-04-01

    Solid-state batteries are a promising option toward high energy and power densities due to the use of lithium (Li) metal as an anode. Among all solid electrolyte materials ranging from sulfides to oxides and oxynitrides, cubic garnet-type Li7La3Zr2O12 (LLZO) ceramic electrolytes are superior candidates because of their high ionic conductivity (10(-3) to 10(-4) S/cm) and good stability against Li metal. However, garnet solid electrolytes generally have poor contact with Li metal, which causes high resistance and uneven current distribution at the interface. To address this challenge, we demonstrate a strategy to engineer the garnet solid electrolyte and the Li metal interface by forming an intermediary Li-metal alloy, which changes the wettability of the garnet surface (lithiophobic to lithiophilic) and reduces the interface resistance by more than an order of magnitude: 950 ohm·cm(2) for the pristine garnet/Li and 75 ohm·cm(2) for the surface-engineered garnet/Li. Li7La2.75Ca0.25Zr1.75Nb0.25O12 (LLCZN) was selected as the solid-state electrolyte (SSE) in this work because of its low sintering temperature, stabilized cubic garnet phase, and high ionic conductivity. This low area-specific resistance enables a solid-state garnet SSE/Li metal configuration and promotes the development of a hybrid electrolyte system. The hybrid system uses the improved solid-state garnet SSE Li metal anode and a thin liquid electrolyte cathode interfacial layer. This work provides new ways to address the garnet SSE wetting issue against Li and get more stable cell performances based on the hybrid electrolyte system for Li-ion, Li-sulfur, and Li-oxygen batteries toward the next generation of Li metal batteries.

  9. Spectral reflectance (0.35-2.5 μm) properties of garnets: Implications for remote sensing detection and characterization

    Science.gov (United States)

    Izawa, M. R. M.; Cloutis, E. A.; Rhind, T.; Mertzman, S. A.; Poitras, Jordan; Applin, Daniel M.; Mann, P.

    2018-01-01

    The utility of spectral reflectance for identification of the main end-member garnets: almandine (Fe2+3Al2Si3O12), andradite (Ca3Fe3+2Si3O12), grossular (Ca3Al2Si3O12), pyrope (Mg3Al2Si3O12), spessartine (Mn2+3Al2Si3O12), and uvarovite (Ca3Cr3+2Si3O12) was studied using a suite of 60 garnet samples. Compositional and structural data for the samples, along with previous studies, were used to elucidate the mechanisms that control their spectral reflectance properties. Various cation substitutions result in different spectral properties that can be determine the presence of various optically-active cations and help differentiate between garnet types. It was found that different wavelength regions are sensitive to different compositional and structural properties of garnets. Crystal-field absorptions involving Fe2+ and/or Fe3+ are responsible for the majority of spectral features in the garnet minerals examined here. There can also be spectral features associated with other cations and mechanisms, such as Fe2+-Fe3+ and Fe2+-Ti4+ intervalence charge transfers. The visible wavelength region is useful for identifying the presence of various cations, in particular, Fe (and its oxidation state), Ti4+, Mn2+, and Cr3+. In the case of andradite, spessartine and uvarovite, the visible region absorption bands are characteristic of these garnets in the sense that they are associated with the major cation that distinguishes each: [6]Fe3+ for andradite, [8]Mn2+ for spessartine, and [6]Cr3+ for uvarovite. For grossular, the presence of small amounts of Fe3+ leads to absorption bands near 0.370 and 0.435 μm. These bands are also seen in pyrope-almandine spectra, which also commonly have additional absorption bands, due to the presence of Fe2+. The common presence of Fe2+ in the dodecahedral site of natural garnets gives rise to three Fe2+ spin-allowed absorption bands in the 1.3, 1.7, and 2.3 μm regions, providing a strong spectral fingerprint for all Fe2+-bearing garnets studied

  10. Aluminum gallium nitride (GaN)/GaN high electron mobility transistor-based sensors for glucose detection in exhaled breath condensate.

    Science.gov (United States)

    Chu, Byung Hwan; Kang, Byoung Sam; Hung, Sheng Chun; Chen, Ke Hung; Ren, Fan; Sciullo, Andrew; Gila, Brent P; Pearton, Stephen J

    2010-01-01

    Immobilized aluminum gallium nitride (AlGaN)/GaN high electron mobility transistors (HEMTs) have shown great potential in the areas of pH, chloride ion, and glucose detection in exhaled breath condensate (EBC). HEMT sensors can be integrated into a wireless data transmission system that allows for remote monitoring. This technology offers the possibility of using AlGaN/GaN HEMTs for extended investigations of airway pathology of detecting glucose in EBC without the need for clinical visits. HEMT structures, consisting of a 3-microm-thick undoped GaN buffer, 30-A-thick Al(0.3)Ga(0.7)N spacer, and 220-A-thick silicon-doped Al(0.3)Ga(0.7)N cap layer, were used for fabricating the HEMT sensors. The gate area of the pH, chloride ion, and glucose detection was immobilized with scandium oxide (Sc(2)O(3)), silver chloride (AgCl) thin film, and zinc oxide (ZnO) nanorods, respectively. The Sc(2)O(3)-gated sensor could detect the pH of solutions ranging from 3 to 10 with a resolution of approximately 0.1 pH. A chloride ion detection limit of 10(-8) M was achieved with a HEMT sensor immobilized with the AgCl thin film. The drain-source current of the ZnO nanorod-gated AlGaN/GaN HEMT sensor immobilized with glucose oxidase showed a rapid response of less than 5 seconds when the sensor was exposed to the target glucose in a buffer with a pH value of 7.4. The sensor could detect a wide range of concentrations from 0.5 nM to 125 microM. There is great promise for using HEMT-based sensors to enhance the detection sensitivity for glucose detection in EBC. Depending on the immobilized material, HEMT-based sensors can be used for sensing different materials. These electronic detection approaches with rapid response and good repeatability show potential for the investigation of airway pathology. The devices can also be integrated into a wireless data transmission system for remote monitoring applications. This sensor technology could use the exhaled breath condensate to measure the

  11. Characterization of Gallium Indium Phosphide and Progress of Aluminum Gallium Indium Phosphide System Quantum-Well Laser Diode

    Science.gov (United States)

    Hamada, Hiroki

    2017-01-01

    Highly ordered gallium indium phosphide layers with the low bandgap have been successfully grown on the (100) GaAs substrates, the misorientation toward [01−1] direction, using the low-pressure metal organic chemical vapor deposition method. It is found that the optical properties of the layers are same as those of the disordered ones, essentially different from the ordered ones having two orientations towards [1−11] and [11−1] directions grown on (100) gallium arsenide substrates, which were previously reported. The bandgap at 300 K is 1.791 eV. The value is the smallest ever reported, to our knowledge. The high performance transverse stabilized AlGaInP laser diodes with strain compensated quantum well structure, which is developed in 1992, have been successfully obtained by controlling the misorientation angle and directions of GaAs substrates. The structure is applied to quantum dots laser diodes. This paper also describes the development history of the quantum well and the quantum dots laser diodes, and their future prospects. PMID:28773227

  12. Determining age of Pan African metamorphism using Sm-Nd garnet-whole rock geochronology and phase equilibria modeling in the Tasriwine ophiolite, Sirwa, Anti-Atlas Morocco

    Science.gov (United States)

    Inglis, Jeremy D.; Hefferan, Kevin; Samson, Scott D.; Admou, Hassan; Saquaque, Ali

    2017-03-01

    Sm-Nd garnet-whole rock geochronology and phase equilibria modeling have been used to determine the age and conditions of regional metamorphism within the Tasriwine ophiolite complex, Sirwa, Morocco. Pressure and temperature estimates obtained using a NaCaKFMASHT phase diagram (pseudosection) and garnet core and rim compositions predict that garnet growth began at ∼0.72 GPa and ∼615 °C and ended at ∼0.8 GPa and ∼640 °C. A bulk garnet Sm-Nd age of 647.2 ± 1.7 Ma, calculated from a four point isochron that combines whole rock, garnet full dissolution and two successively more aggressive partial dissolutions, provides a precise date for garnet formation and regional metamorphism. The age is over 15 million years younger than a previous age estimate of regional metamorphism of 663 ± 13 Ma based upon a SHRIMP U-Pb date from rims on zircon from the Iriri migmatite. The new data provide further constraints on the age and nature of regional metamorphism in the Anti-Atlas mountains and emphasizes that garnet growth during regional metamorphism may not necessarily coincide with magmatism/anatexis which predominate the signature witnessed by previous U-Pb studies. The ability to couple PT estimates for garnet formation with high precision Sm-Nd geochronology highlights the utility of garnet studies for uncovering the detailed metamorphic history of the Anti-Atlas mountain belt.

  13. Clinical evaluation of chest x-rays, gallium-67 scans and CT scans in sarcoidosis

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, S.; Maeda, T. (Kochi Medical School (Japan)); Itoh, K.; Yamamoto, Y.; Machida, K.

    1981-10-01

    A comparative study of the accuracy of chest X-rays, Gallium-67 scans and CT scans for mediastinal lymphadenopathy of pulmonary sarcoidosis was performed. The ability of each examination to detect the lymphadenopathy of following 5 lymph node groups was evaluated, such as paratracheal, aorto-pulmonic window, subcarinal and both hilar lymph nodes. The results on 5 patients indicated that in the detection of right paratracheal and subcarinal lymphadenopathy, Gallium scans and CT scans were more sensitive than chest x-rays. Chest x-rays and Gallium scans were superior than CT in detecting bilateral hilar lymphadenopathy. In the involvement of aorto-pulmonic window nodes, Gallium scans and chest x-rays were more informative than CT. Combination of these three examination is effective in the detection of the above described lymphadenopathy.

  14. High-power X- and Ka-band Gallium Nitride Amplifiers with Exceptional Efficiency Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Achieving very high-power amplification with maximum efficiency at X- and Ka-band is challenging using solid-state technology. Gallium Arsenide (GaAs) has been the...

  15. Homogeneous dispersion of gallium nitride nanoparticles in a boron nitride matrix by nitridation with urea.

    Science.gov (United States)

    Kusunose, Takafumi; Sekino, Tohru; Ando, Yoichi

    2010-07-01

    A Gallium Nitride (GaN) dispersed boron nitride (BN) nanocomposite powder was synthesized by heating a mixture of gallium nitrate, boric acid, and urea in a hydrogen atmosphere. Before heat treatment, crystalline phases of urea, boric acid, and gallium nitrate were recognized, but an amorphous material was produced by heat treatment at 400 degrees C, and then was transformed into GaN and turbostratic BN (t-BN) by further heat treatment at 800 degrees C. TEM obsevations of this composite powder revealed that single nanosized GaN particles were homogeneously dispersed in a BN matrix. Homogeneous dispersion of GaN nanoparticles was thought to be attained by simultaneously nitriding gallium nitrate and boric acid to GaN and BN with urea.

  16. Two-in-One Biointerfaces-Antimicrobial and Bioactive Nanoporous Gallium Titanate Layers for Titanium Implants

    National Research Council Canada - National Science Library

    Seiji Yamaguchi; Shekhar Nath; Yoko Sugawara; Kamini Divakarla; Theerthankar Das; Jim Manos; Wojciech Chrzanowski; Tomiharu Matsushita; Tadashi Kokubo

    2017-01-01

    The inhibitory effect of gallium (Ga) ions on bone resorption and their superior microbial activity are attractive and sought-after features for the vast majority of implantable devices, in particular for implants used for hard tissue...

  17. A New Type of Kelyphite Produced by Isochemical Breakdown of Garnet, Discovered from the Czech Moldanubian Zone

    Science.gov (United States)

    Obata, M.; Ozawa, K.; Naemura, K.; Ueda, T.

    2011-12-01

    Kelyphite is a fine-grained, mineral intergrowth developed around garnet in many mafic and ultramafic rocks of high-pressure origin. Typical mineral assemblage of kelyphites developed in garnet peridotites is Opx+Cpx+spinel ±amphibole, which has been interpreted to be a reaction product between garnet and olivine (Kushiro and Yoder, 1966), which is referred to as kelyphite I. In general, these kelyphites are not isochemical to mother garnet but a significant gain of Mg and loss of Al occur with respect to original garnets (e.g. Obata, 2011). We found, probably for the first time in the world, a new type of kelyphite (named kelyphite II) that appears to have been formed by an isochemical breakdown of garnet inside kelyphite I in a garnet peridotite from the Czech Moldanubian Zone. The garnet peridotite had once equilibrated at 2.3-3.5 GPa, 850-1030°C and were partially re-equilibrated in the spinel-lherzolites facies as it ascended and was incorporated into a thickened lower continental crust (Naemura et al., 2009). The temperature of the kelyphite I formation has been estimated to be 730-770°C by applying two-pyroxene geothermometer. The kelyphite II is much finer-grained and darker-colored than kelyphite I and shows a very straight lamellar structure consisting of Opx, spinel and plagioclase (anorthite), in which spinel occur exclusively within the Opx lamella (less than 1 micron thickness). Furthermore, the kelyphite II is typically separated from adjacent garnet by a thin hydrous zone (10 to 20 micron width) that consists of amphibole and spinel-like fine lamella (named kelyphite III), the bulk of which contains more Ca and Na (and therefore less Mg and Fe) than the garnet. The transitional boundary between the kelyphite I and kelyphite II areas (typically of hundreds of microns width) may be divided into several mineral zones of distinct mineral assemblages that all contain Ca-amphibole (pargasitic hornblende). Microprobe analyses revieled that Opx in

  18. Synthesis and characterization of reduced scandium halide containing one- and two-dimensional metal bonded arrays. [Sc--ScCl3; Cs3Sc2Cl9; CsScCl3

    Energy Technology Data Exchange (ETDEWEB)

    Poeppelmeier, K.R.

    1978-08-01

    The stabilization effect of metal-metal bond formation on reduced scandium compounds was studied. The binary compounds Sc/sub 7/Cl/sub 12/, Sc/sub 5/Cl/sub 8/, Sc/sub 7/Cl/sub 10/ and ScCl were prepared by high temperature techniques and were characterized by single crystal x-ray diffraction. The respective metal arrays in these compounds can be viewed as fragments of scandium metal ranging from discrete six atom metal cluster species (Sc(Sc/sub 6/Cl/sub 12/)), through intermediate single and double infinite chain configurations ((ScCl/sub 2/)(Sc/sub 4/Cl/sub 6/)) and ((ScCl/sub 2/)(Sc/sub 6/Cl/sub 8/)) to double metal close-packed sheets (ScCl). The halogen atoms effectively isolate the clusters, chains and sheets by bonding face, edge or exo positions on the metal arrays. The common occurrence of isolated scandium (III) ions emphasizes that a minimum number of bonding electrons is required to stabilize what are formally anionic metal arrays. The distribution of the reduction electrons in these anisotropic materials was studied by magnetic susceptibility, EPR and uv-X photoelectron spectroscopy. The ternary compounds studied were Cs/sub 3/Sc/sub 2/Cl/sub 9/ and CsScCl/sub 3/. The anion-bridged metal chain of the hexagonal perovskite structure was found to stabilize scandium (II). CsScCl/sub 3/ was found to be grossly nonstoichiometric on the transition metal site and the effects of the mixed valence character were studied between the single valence extremes Cs/sub 3/Sc/sub 2 + x/Cl/sub 9/; 0< x < 1.0.

  19. 68Gallium-DOTATATE PET/CT Scanning Results in Patients with MEN1

    Science.gov (United States)

    Sadowski, Samira M; Millo, Corina; Cottle-Delisle, Candice; Merkel, Roxanne; Yang, Lily A; Herscovitch, Peter; Pacak, Karel; Simonds, William F; Marx, Stephen J; Kebebew, Electron

    2015-01-01

    Background Screening for neuroendocrine tumors (NETs) in patients with multiple endocrine neoplasia type 1 (MEN1) is recommended to detect primary and metastatic tumors, which can result in significant morbidity and mortality. The utility of somatostatin receptor imaging 68Gallium-DOTATATE PET/CT in patients with MEN1 is not known. The aim of this study was to prospectively determine the accuracy of 68Gallium-DOTATATE PET/CT versus 111In-pentetreotide SPECT/CT and anatomic imaging in patients with MEN1. Study design Prospective study comparing 68Gallium-DOTATATE PET/CT, 111In-pentetreotide SPECT/CT, and triphasic CT scan to clinical, biochemical and pathological data in 26 patients with MEN1. Results 68Gallium-DOTATATE PET/CT detected 107 lesions; 111In- pentetreotide SPECT/CT detected 33 lesions; and CT scan detected 48 lesions. Lesions detected on 68Gallium-DOTATATE PET/CT had high SUVmax (median SUVmax = 72.8 [range 19–191]). In 7 of the 26 patients (27%), 68Gallium-DOTATATE PET/CT was positive with a negative 111In-pentetreotide SPECT/CT, and in 10 patients (38.5%), additional metastases were detected (range 0.3 cm to 1.5 cm). In 8 of the 26 patients (31%), there was a change in management recommendations as a result of the findings on 68Gallium-DOTATATE PET/CT that were not seen on 111In- pentetreotide SPECT/CT and CT scan. Conclusions 68Gallium-DOTATATE PET/CT is more sensitive for detecting NETs than 111In-pentetreotide SPECT/CT and CT scan in patients with MEN1. This imaging technique should be integrated into radiologic screening and surveillance of patients with MEN1, as it can significantly alter management recommendations. PMID:26206648

  20. Heterotopic ossification (myositis ossificans) in acquired immune deficiency syndrome. Detection by gallium scintigraphy.

    Science.gov (United States)

    Drane, W E; Tipler, B M

    1987-06-01

    A case of heterotopic ossification (myositis ossificans) secondary to the central nervous system complications of acquired immune deficiency syndrome (AIDS) is reported. Because of the overwhelming suspicion of infection in this patient, this diagnosis was not considered until a gallium scan revealed the typical findings of heterotopic ossification. Because of the increasing utilization of gallium imaging in the AIDS population, every imaging specialist should be aware of this potential disorder.

  1. The Role of Gallium Scanning in the Detection of Bone and Joint Sepsis

    OpenAIRE

    Gavin, Anna; Laird, J. D.; Roberts, S D

    1984-01-01

    The value of gallium (67Ga) scanning in the diagnosis of septic disease of bone or joint was assessed in 34 patients. The results show a sensitivity of 60 per cent and specificity of 64 per cent. The low accuracy of this method for the detection of bone and joint sepsis (62 per cent) means that gallium scanning can be used only as an adjunct to other investigative techniques.

  2. Detection of insulinoma using 68Gallium-DOTATATE PET/CT: a case report

    OpenAIRE

    Sadowski, Samira M.; Neychev, Vladimir; Cottle-Delisle, Candice; Merkel, Roxanne; Yang, Lily A.; Quezado, Martha M.; Chang, Richard; Kebebew, Electron

    2014-01-01

    Insulinomas are the most common cause of endogenous hyperinsulinemic hypoglycemia in non-diabetic adults. They are most often benign, small and difficult to localize with current imaging techniques. This is of high importance, as complete surgical resection is the only curative treatment. Anatomic imaging, 111In-pentetreotide scan and 68Gallium-DOTATATE positron emission tomography/computed tomography (PET/CT) were compared in a patient with insulinoma. 68Gallium-DOTATATE PET/CT and selective...

  3. Recognition of distinctive patterns of gallium-67 distribution in sarcoidosis

    Energy Technology Data Exchange (ETDEWEB)

    Sulavik, S.B.; Spencer, R.P.; Weed, D.A.; Shapiro, H.R.; Shiue, S.T.; Castriotta, R.J. (Univ. of Connecticut School of Medicine, Farmington (USA))

    1990-12-01

    Assessment of gallium-67 ({sup 67}Ga) uptake in the salivary and lacrimal glands and intrathoracic lymph nodes was made in 605 consecutive patients including 65 with sarcoidosis. A distinctive intrathoracic lymph node {sup 67}Ga uptake pattern, resembling the Greek letter lambda, was observed only in sarcoidosis (72%). Symmetrical lacrimal gland and parotid gland {sup 67}Ga uptake (panda appearance) was noted in 79% of sarcoidosis patients. A simultaneous lambda and panda pattern (62%) or a panda appearance with radiographic bilateral, symmetrical, hilar lymphadenopathy (6%) was present only in sarcoidosis patients. The presence of either of these patterns was particularly prevalent in roentgen Stages I (80%) or II (74%). We conclude that simultaneous (a) lambda and panda images, or (b) a panda image with bilateral symmetrical hilar lymphadenopathy on chest X-ray represent distinctive patterns which are highly specific for sarcoidosis, and may obviate the need for invasive diagnostic procedures.

  4. Compilation of gallium resource data for bauxite deposits

    Science.gov (United States)

    Schulte, Ruth F.; Foley, Nora K.

    2014-01-01

    Gallium (Ga) concentrations for bauxite deposits worldwide have been compiled from the literature to provide a basis for research regarding the occurrence and distribution of Ga worldwide, as well as between types of bauxite deposits. In addition, this report is an attempt to bring together reported Ga concentration data into one database to supplement ongoing U.S. Geological Survey studies of critical mineral resources. The compilation of Ga data consists of location, deposit size, bauxite type and host rock, development status, major oxide data, trace element (Ga) data and analytical method(s) used to derive the data, and tonnage values for deposits within bauxite provinces and districts worldwide. The range in Ga concentrations for bauxite deposits worldwide is

  5. Design and Performance Estimates of an Ablative Gallium Electromagnetic Thruster

    Science.gov (United States)

    Thomas, Robert E.

    2012-01-01

    The present study details the high-power condensable propellant research being conducted at NASA Glenn Research Center. The gallium electromagnetic thruster is an ablative coaxial accelerator designed to operate at arc discharge currents in the range of 10-25 kA. The thruster is driven by a four-parallel line pulse forming network capable of producing a 250 microsec pulse with a 60 kA amplitude. A torsional-type thrust stand is used to measure the impulse of a coaxial GEM thruster. Tests are conducted in a vacuum chamber 1.5 m in diameter and 4.5 m long with a background pressure of 2 microtorr. Electromagnetic scaling calculations predict a thruster efficiency of 50% at a specific impulse of 2800 seconds.

  6. Modeling and simulation of bulk gallium nitride power semiconductor devices

    Directory of Open Access Journals (Sweden)

    G. Sabui

    2016-05-01

    Full Text Available Bulk gallium nitride (GaN power semiconductor devices are gaining significant interest in recent years, creating the need for technology computer aided design (TCAD simulation to accurately model and optimize these devices. This paper comprehensively reviews and compares different GaN physical models and model parameters in the literature, and discusses the appropriate selection of these models and parameters for TCAD simulation. 2-D drift-diffusion semi-classical simulation is carried out for 2.6 kV and 3.7 kV bulk GaN vertical PN diodes. The simulated forward current-voltage and reverse breakdown characteristics are in good agreement with the measurement data even over a wide temperature range.

  7. Temperature-dependent structure evolution in liquid gallium

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, L. H.; Wang, X. D.; Yu, Q.; Zhang, H.; Zhang, F.; Sun, Y.; Cao, Q. P.; Xie, H. L.; Xiao, T. Q.; Zhang, D. X.; Wang, C. Z.; Ho, K. M.; Ren, Y.; Jiang, J. Z.

    2017-04-01

    Temperature-dependent atomistic structure evolution of liquid gallium (Ga) has been investigated by using in situ high energy X-ray diffraction experiment and ab initio molecular dynamics simulation. Both experimental and theoretical results reveal the existence of a liquid structural change around 1000 K in liquid Ga. Below and above this temperature the liquid exhibits differences in activation energy for selfdiffusion, temperature-dependent heat capacity, coordination numbers, density, viscosity, electric resistivity and thermoelectric power, which are reflected from structural changes of the bond-orientational order parameter Q6, fraction of covalent dimers, averaged string length and local atomic packing. This finding will trigger more studies on the liquid-to-liquid crossover in metallic melts.

  8. Localized surface phonon polariton resonances in polar gallium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Kaijun, E-mail: kfeng@nd.edu; Islam, S. M.; Verma, Jai; Hoffman, Anthony J. [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Streyer, William; Wasserman, Daniel [Department of Electrical and Computer Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States); Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14850 (United States)

    2015-08-24

    We demonstrate the excitation of localized surface phonon polaritons in an array of sub-diffraction pucks fabricated in an epitaxial layer of gallium nitride (GaN) on a silicon carbide (SiC) substrate. The array is characterized via polarization- and angle-dependent reflection spectroscopy in the mid-infrared, and coupling to several localized modes is observed in the GaN Reststrahlen band (13.4–18.0 μm). The same structure is simulated using finite element methods and the charge density of the modes are studied; transverse dipole modes are identified for the transverse electric and magnetic polarizations and a quadrupole mode is identified for the transverse magnetic polarization. The measured mid-infrared spectrum agrees well with numerically simulated spectra. This work could enable optoelectronic structures and devices that support surface modes at mid- and far-infrared wavelengths.

  9. Gallium-doped zinc oxide prepared by the Pechini method

    OpenAIRE

    Gonçalves, Agnaldo de Souza [UNESP; Lima, Sergio Antonio Marques de [UNESP; Davolos, Marian Rosaly [UNESP

    2002-01-01

    Óxido de zinco dopado com gálio (ZnO:Ga) foi preparado pelo método Pechini a partir de citrato de zinco e hidróxido de gálio. Utilizsando este método, foi possível obter ZnO:Ga cristalino pela calcinação do precursor polimérico em ar a 900ºC por 4 horas. A resina homogênea contendo 2% de dopante só pôde ser obtida com a adição de ácido etilenodiaminotetracético (edta). A adição do edta, também, ocasionou a diminuição de tamanho de partícula do óxido. Gallium-doped zinc oxide (ZnO:Ga) was p...

  10. Gallium Nitride Electrical Characteristics Extraction and Uniformity Sorting

    Directory of Open Access Journals (Sweden)

    Shyr-Long Jeng

    2015-01-01

    Full Text Available This study examined the output electrical characteristics—current-voltage (I-V output, threshold voltage, and parasitic capacitance—of novel gallium nitride (GaN power transistors. Experimental measurements revealed that both enhanced- and depletion-mode GaN field-effect transistors (FETs containing different components of identical specifications yielded varied turn-off impedance; hence, the FET quality was inconsistent. Establishing standardized electrical measurements can provide necessary information for designers, and measuring transistor electrical characteristics establishes its equivalent-circuit model for circuit simulations. Moreover, high power output requires multiple parallel power transistors, and sorting the difference between similar electrical characteristics is critical in a power system. An isolated gate driver detection method is proposed for sorting the uniformity from the option of the turn-off characteristic. In addition, an equivalent-circuit model for GaN FETs is established on the basis of the measured electrical characteristics and verified experimentally.

  11. Low-threshold indium gallium nitride quantum dot microcavity lasers

    Science.gov (United States)

    Woolf, Alexander J.

    Gallium nitride (GaN) microcavities with embedded optical emitters have long been sought after as visible light sources as well as platforms for cavity quantum electrodynamics (cavity QED) experiments. Specifically, materials containing indium gallium nitride (InGaN) quantum dots (QDs) offer an outstanding platform to study light matter interactions and realize practical devices, such as on-chip light emitting diodes and nanolasers. Inherent advantages of nitride-based microcavities include low surface recombination velocities, enhanced room-temperature performance (due to their high exciton binding energy, as high as 67 meV for InGaN QDs), and emission wavelengths in the blue region of the visible spectrum. In spite of these advantages, several challenges must be overcome in order to capitalize on the potential of this material system. Such diffculties include the processing of GaN into high-quality devices due to the chemical inertness of the material, low material quality as a result of strain-induced defects, reduced carrier recombination effciencies due to internal fields, and a lack of characterization of the InGaN QDs themselves due to the diffculty of their growth and therefore lack of development relative to other semiconductor QDs. In this thesis we seek to understand and address such issues by investigating the interaction of light coupled to InGaN QDs via a GaN microcavity resonator. Such coupling led us to the demonstration of the first InGaN QD microcavity laser, whose performance offers insights into the properties and current limitations of the nitride materials and their emitters. This work is organized into three main sections. Part I outlines the key advantages and challenges regarding indium gallium nitride (InGaN) emitters embedded within gallium nitride (GaN) optical microcavities. Previous work is also discussed which establishes context for the work presented here. Part II includes the fundamentals related to laser operation, including the

  12. Fabrication and properties of gallium phosphide variable colour displays

    Science.gov (United States)

    Effer, D.; Macdonald, R. A.; Macgregor, G. M.; Webb, W. A.; Kennedy, D. I.

    1973-01-01

    The unique properties of single-junction gallium phosphide devices incorporating both red and green radiative recombination centers were investigated in application to the fabrication of monolithic 5 x 7 displays capable of displaying symbolic and alphanumeric information in a multicolor format. A number of potentially suitable material preparation techniques were evaluated in terms of both material properties and device performance. Optimum results were obtained for double liquid-phase-epitaxial process in which an open-tube dipping technique was used for n-layer growth and a sealed tipping procedure for subsequent p-layer growth. It was demonstrated that to prepare devices exhibiting a satisfactory range of dominant wavelengths which can be perceived as distinct emission colors extending from the red through green region of the visible spectrum involves a compromise between the material properties necessary for efficient red emission and those considered optimum for efficient green emission.

  13. Using thermodynamic modelling, quartz-in-garnet geobarometry and monazite geochronology to understand Early Jurassic orogenesis in the Northern Canadian Cordillera

    Science.gov (United States)

    Clark, Andy; Gibson, Dan; Ashley, Kyle; Staples, Reid; Israel, Steve

    2017-04-01

    Polydeformed mid-crustal rocks crop out throughout much of the Northern Canadian Cordillera in Yukon, Canada, yet the timing and conditions of deformation and metamorphism are not well constrained in many areas. Regional mapping, in-situ monazite U-Pb geochronology, quartz-in-garnet geobarometry and thermodynamic modelling indicate that parts of southwest Yukon experienced tectonic burial to 25-30 kilometres by 199 Ma. Decompression was accompanied by widespread high-Y monazite growth around 185 Ma. These results highlight the significance of thick-skinned Early Jurassic orogenesis in the Northern Canadian Cordillera. Data obtained using garnet isopleth thermobarometry and pseudosection modelling indicate that garnet grew along a positive P-T gradient, with garnet nucleation at 0.3-0.4 GPa and 500-550°C. Modelling constrains peak metamorphic conditions to 0.6-0.8 GPa and 650°C. Pressure estimates obtained using Raman spectra of quartz inclusions in garnet cores (quartz-in-garnet geobarometry) also suggest that garnet nucleation occurred at pressures of 0.3-0.4 GPa. However, pressures obtained from inclusions outside of garnet cores vary between 0.3 and 0.7 GPa, with some intervals of garnet growth apparently accompanied by a decrease in pressure. Therefore, these data are not consistent with garnet growth along a simple positive P-T gradient, as suggested by thermodynamic modelling. Our results highlight discrepancies between metamorphic conditions obtained using thermodynamic modelling compared with those obtained using quartz-in-garnet geobarometry. This brings into question the accuracy of P-T paths obtained by using techniques, such as pseudosection modelling, which often cannot resolve such paths in detail. Nevertheless, the consistent garnet core pressures obtained in this study suggest that garnet growth initiated at near equilibrium P-T-X conditions. A subsequent departure from equilibrium conditions would explain the discrepancy between thermodynamic

  14. Preparation of gallium oxynitride powder and its nanofibers by the nitridation of a gallium oxide precursor doped with nickel or cobalt obtained via the citrate route.

    Science.gov (United States)

    Miyaake, A; Masubuchi, Y; Takeda, T; Motohashi, T; Kikkawa, S

    2010-07-14

    Acicular crystals were grown in gallium oxynitride powder prepared by ammonia nitridation of amorphous gallium oxide precursors containing less than 5 at% of either Ni or Co, via the citrate route. The crystals were several tens of nanometres wide, several micrometres long, and grown in the temperature range 750 to 850 degrees C in a flow of ammonia of less than 200 mL min(-1). The crystal structure of the gallium oxynitride was a highly disordered 2H wurtzite-type with some 3C zinc blende-type stacking faults. The crystals grew in their basal plane changing their aspect ratio with the supplying method of small amounts of Ni or Co and an amount of residual carbon. The acicular crystals were grown by the catalytic behavior of Ni or Co to enhance one-dimensional growth in the hexagonal c-plane.

  15. Toward garnet electrolyte–based Li metal batteries: An ultrathin, highly effective, artificial solid-state electrolyte/metallic Li interface

    Science.gov (United States)

    Fu, Kun (Kelvin); Gong, Yunhui; Liu, Boyang; Zhu, Yizhou; Xu, Shaomao; Yao, Yonggang; Luo, Wei; Wang, Chengwei; Lacey, Steven D.; Dai, Jiaqi; Chen, Yanan; Mo, Yifei; Wachsman, Eric; Hu, Liangbing

    2017-01-01

    Solid-state batteries are a promising option toward high energy and power densities due to the use of lithium (Li) metal as an anode. Among all solid electrolyte materials ranging from sulfides to oxides and oxynitrides, cubic garnet–type Li7La3Zr2O12 (LLZO) ceramic electrolytes are superior candidates because of their high ionic conductivity (10−3 to 10−4 S/cm) and good stability against Li metal. However, garnet solid electrolytes generally have poor contact with Li metal, which causes high resistance and uneven current distribution at the interface. To address this challenge, we demonstrate a strategy to engineer the garnet solid electrolyte and the Li metal interface by forming an intermediary Li-metal alloy, which changes the wettability of the garnet surface (lithiophobic to lithiophilic) and reduces the interface resistance by more than an order of magnitude: 950 ohm·cm2 for the pristine garnet/Li and 75 ohm·cm2 for the surface-engineered garnet/Li. Li7La2.75Ca0.25Zr1.75Nb0.25O12 (LLCZN) was selected as the solid-state electrolyte (SSE) in this work because of its low sintering temperature, stabilized cubic garnet phase, and high ionic conductivity. This low area-specific resistance enables a solid-state garnet SSE/Li metal configuration and promotes the development of a hybrid electrolyte system. The hybrid system uses the improved solid-state garnet SSE Li metal anode and a thin liquid electrolyte cathode interfacial layer. This work provides new ways to address the garnet SSE wetting issue against Li and get more stable cell performances based on the hybrid electrolyte system for Li-ion, Li-sulfur, and Li-oxygen batteries toward the next generation of Li metal batteries. PMID:28435874

  16. Novel ethylenediamine-gallium phosphate containing 6-fold coordinated gallium atoms with unusual four equatorial Ga–N bonds

    Energy Technology Data Exchange (ETDEWEB)

    Torre-Fernández, Laura [Departamentos de Química Física y Analítica y Química Orgánica e Inorgánica, Universidad de Oviedo-CINN, 33006 Oviedo (Spain); Espina, Aránzazu; Khainakov, Sergei A.; Amghouz, Zakariae [Servicios Científico Técnicos, Universidad de Oviedo, 33006 Oviedo (Spain); García, José R. [Departamentos de Química Física y Analítica y Química Orgánica e Inorgánica, Universidad de Oviedo-CINN, 33006 Oviedo (Spain); García-Granda, Santiago, E-mail: sgg@uniovi.es [Departamentos de Química Física y Analítica y Química Orgánica e Inorgánica, Universidad de Oviedo-CINN, 33006 Oviedo (Spain)

    2014-07-01

    A novel ethylenediamine-gallium phosphate, formulated as Ga(H{sub 2}NCH{sub 2}CH{sub 2}NH{sub 2}){sub 2}PO{sub 4}·2H{sub 2}O, was synthesized under hydrothermal conditions. The crystal structure, including hydrogen positions, was determined using single-crystal X-ray diffraction data (monoclinic, a=9.4886(3) Å, b=6.0374(2) Å, c=10.2874(3) Å, and β=104.226(3)°, space group Pc) and the bulk was characterized by chemical (Ga–P–C–H–N) and thermal analysis (TG–MS and DSC), including activation energy data of its thermo-oxidative degradation, powder X-ray diffraction (PXRD), solid-state nuclear magnetic resonance (SS-NMR) measurements, and transmission electron microscopy (TEM, SAED/NBD, and STEM BF-EDX). The crystal structure is built up of infinite zig-zag chains running along the c-axis, formed by vertex-shared (PO{sub 4}) and (GaO{sub 2}N{sub 4}) polyhedra. The new compound is characterized by unusual four equatorial Ga–N bonds coming from two nonequivalent ethylenediamine molecules and exhibits strong blue emission at 430 nm (λ{sub ex}=350 nm) in the solid state at room temperature. - Graphical abstract: Single crystals of a new ethylenediamine-gallium phosphate, Ga(H{sub 2}NCH{sub 2}CH{sub 2}NH{sub 2}){sub 2}PO{sub 4}·2H{sub 2}O, were obtained and the structural features presented. This structure is one of the scarce examples of GaPO with Ga–N bonds reported. - Highlights: • A novel ethylenediamine-gallium phosphate was hydrothermally synthesized. • The new compound is characterized by unusual four equatorial Ga–N bonds. • Void-volume analysis shows cages and channels with sizes ideally suited to accommodate small molecules. • The new compound exhibits strong blue emission.

  17. Gallium phosphinoarylbisthiolato complexes counteract drug resistance of cancer cells.

    Science.gov (United States)

    Fischer-Fodor, Eva; Vălean, Ana-Maria; Virag, Piroska; Ilea, Petru; Tatomir, Corina; Imre-Lucaci, Florica; Schrepler, Maria Perde; Krausz, Ludovic Tibor; Tudoran, Lucian Barbu; Precup, Calin George; Lupan, Iulia; Hey-Hawkins, Evamarie; Silaghi-Dumitrescu, Luminita

    2014-04-01

    In cancer therapy the platinum-based drugs are used frequently with a good clinical outcome, but besides unwanted side effects which occur, the tumour cells subjected to treatment are prone to develop tolerance or even multidrug resistance (MDR). Metal compounds with a central atom other than platinum are efficient in targeting the chemoresistant cells, therefore the biological outcome of two recently synthesized gallium phosphinoarylbisthiolato complexes was studied, having the formula [X][Ga{PPh(2-SC6H4)2-κ(3)S,S',P}{PPh(2-SC6H4)2-κ(2)S,S'}] where [X] is either the NEt3H (1) or PPh4 (2) cation. Compounds 1 and 2 display in vitro cytotoxicity against both platinum-sensitive and platinum-resistant cell lines (A2780 and A2780cis). Morphological and ultrastructural evidence points toward their capacity to impair tumour cells survival. This behaviour is based on malignant cells capacity to selectively intake gallium, and to bind to the cellular DNA. They are able to cause massive DNA damage in treated cancer cells, focusing on 7-methylguanine and 8-oxoguanine sites and oxidizing the pyrimidine bases; this leads to early apoptosis of a significant percent of treated cells. The intrinsic and extrinsic apoptotic pathways are influenced through the modulation of gene expression following the treatment with complexes 1 and 2, which accompanies the negative regulation of P-glycoprotein 1 (Pgp-1), an important cellular ABC-type transporter from the multidrug resistance (MDR) family. The studied Ga(III) compounds demonstrated the capacity to counteract the chemoresistance mechanisms in the tumours defiant to standard drug action. Compound 2 shows a good anticancer potential and it could represent an alternative to platinum-based drugs especially in the situation of standard treatment failure.

  18. High-Temperature Decomposition of Brønsted Acid Sites in Gallium-Substituted Zeolites

    Energy Technology Data Exchange (ETDEWEB)

    K Al-majnouni; N Hould; W Lonergan; D Vlachos; R Lobo

    2011-12-31

    The dehydroxylation of Broensted acid sites (BAS) in Ga-substituted zeolites was investigated at temperatures up to 850 C using X-ray absorption spectroscopy (XAS), Fourier transform infrared spectroscopy (FTIR), and mass spectrometry-temperature programmed desorption (MS-TPD). X-ray absorption near-edge spectroscopy (XANES) revealed that the majority of gallium has tetrahedral coordination even after complete dehydroxylation. The interatomic gallium-oxygen distance and gallium coordination number determined by extended X-ray absorption fine structure (EXAFS) are consistent with gallium in tetrahedral coordination at low T (< 550 C). Upon heating Ga-Beta and Ga-ZSM5 to 850 C, analysis of the EXAFS showed that 70 and 80% of the gallium was still in tetrahedral coordination. The remainder of the gallium was found to be in octahedral coordination. No trigonal Ga atoms were observed. FTIR measurements carried out at similar temperatures show that the intensity of the OH vibration due to BAS has been eliminated. MS-TPD revealed that hydrogen in addition to water evolved from the samples during dehydroxylation. This shows that dehydrogenation in addition to dehydration is a mechanism that contributes to BAS decomposition. Dehydrogenation was further confirmed by exposing the sample to hydrogen to regenerate some of the BAS as monitored by FTIR and MS-TPD.

  19. Design and properties of novel gallium-doped injectable apatitic cements.

    Science.gov (United States)

    Mellier, Charlotte; Fayon, Franck; Boukhechba, Florian; Verron, Elise; LeFerrec, Myriam; Montavon, Gilles; Lesoeur, Julie; Schnitzler, Verena; Massiot, Dominique; Janvier, Pascal; Gauthier, Olivier; Bouler, Jean-Michel; Bujoli, Bruno

    2015-09-01

    Different possible options were investigated to combine an apatitic calcium phosphate cement with gallium ions, known as bone resorption inhibitors. Gallium can be either chemisorbed onto calcium-deficient apatite or inserted in the structure of β-tricalcium phosphate, and addition of these gallium-doped components into the cement formulation did not significantly affect the main properties of the biomaterial, in terms of injectability and setting time. Under in vitro conditions, the amount of gallium released from the resulting cement pellets was found to be low, but increased in the presence of osteoclastic cells. When implanted in rabbit bone critical defects, a remodeling process of the gallium-doped implant started and an excellent bone interface was observed. The integration of drugs and materials is a growing force in the medical industry. The incorporation of pharmaceutical products not only promises to expand the therapeutic scope of biomaterials technology but to design a new generation of true combination products whose therapeutic value stem equally from both the structural attributes of the material and the intrinsic therapy of the drug. In this context, for the first time an injectable calcium phosphate cement containing gallium was designed with properties suitable for practical application as a local delivery system, implantable by minimally invasive surgery. This important and original paper reports the design and in-depth chemical and physical characterization of this groundbreaking technology. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  20. Formation of self-organized nanoporous anodic oxide from metallic gallium.

    Science.gov (United States)

    Pandey, Bipin; Thapa, Prem S; Higgins, Daniel A; Ito, Takashi

    2012-09-25

    This paper reports the formation of self-organized nanoporous gallium oxide by anodization of solid gallium metal. Because of its low melting point (ca. 30 °C), metallic gallium can be shaped into flexible structures, permitting the fabrication of nanoporous anodic oxide monoliths within confined spaces like the inside of a microchannel. Here, solid gallium films prepared on planar substrates were employed to investigate the effects of anodization voltage (1, 5, 10, 15 V) and H(2)SO(4) concentration (1, 2, 4, 6 M) on anodic oxide morphology. Self-organized nanopores aligned perpendicular to the film surface were obtained upon anodization of gallium films in ice-cooled 4 and 6 M aqueous H(2)SO(4) at 10 and 15 V. Nanopore formation could be recognized by an increase in anodic current after a current decrease reflecting barrier oxide formation. The average pore diameter was in the range of 18-40 nm with a narrow diameter distribution (relative standard deviation ca. 10-20%), and was larger at lower H(2)SO(4) concentration and higher applied voltage. The maximum thickness of nanoporous anodic oxide was ca. 2 μm. In addition, anodic formation of self-organized nanopores was demonstrated for a solid gallium monolith incorporated at the end of a glass capillary. Nanoporous anodic oxide monoliths formed from a fusible metal will lead to future development of unique devices for chemical sensing and catalysis.

  1. Garnet effect on Nd-Hf isotope decoupling: Evidence from the Jinfosi batholith, Northern Tibetan Plateau

    Science.gov (United States)

    Huang, Hui; Niu, Yaoling; Mo, Xuanxue

    2017-03-01

    The initial Nd and Hf isotope ratios of a 420 Ma post-collisional dioritic-granitic batholith from the Northern Tibetan plateau define a negative trend above and orthogonal to the ԐHf(t)-ԐNd(t) terrestrial array. This uncommon trend offers an insight into the origin of the puzzling Nd-Hf isotope decoupling in the crustal rocks. On this trend, samples depleted in heavy rare earth elements (HREEs, i.e., [Dy/Yb]N ≫ 1) deviate most from the terrestrial array whereas samples with flat HREEs (i.e., [Dy/Yb]N ≥ 1) deviate less or plot within the terrestrial array, pointing to the controlling effect of garnet in the magma source. Ancient garnet-bearing residues after melt extraction will have elevated Lu/Hf ratios and can evolve with time to produce high ԐHf(t) at a low ԐNd(t) value. Mixing of melts derived from such source lithologies (high Lu/Hf) with melts possessing a within-terrestrial array Nd-Hf isotopic composition (low Lu/Hf) best explains the observed trend orthogonal to the terrestrial array. The samples from the Jinfosi batholith with the most decoupled Nd-Hf isotope compositions require a larger degree (> 40%) and ancient (i.e., ≥ 1.8 Gyr) previous melt extraction from their source. It follows that the ancient melts with depleted HREEs complementary to those garnet-bearing residues should have low ԐHf values and plot below the terrestrial array, which is indeed shown by some Archean/Paleoproterozic TTGs.

  2. Raman spectroscopic study of synthetic pyrope-grossular garnets: structural implications

    Science.gov (United States)

    Du, Wei; Han, Baofu; Clark, Simon Martin; Wang, Yichuan; Liu, Xi

    2017-06-01

    A study of the effect of substitution of Mg and Ca in garnet solid solution (Grtss) was carried out using Raman spectroscopy to probe changes to the crystal lattice. The garnet solid solutions with composition changing along pyrope (Py; Mg3Al2Si3O12) and grossular (Gr; Ca3Al2Si3O12) binary were synthesized from glass at 6 GPa and 1400 °C and a second series of Grtss with composition Py40Gr60 were synthesized at 6 GPa but different temperatures from 1000 to 1400 °C. Raman mode assignments were made based on a comparison with the two end members pyrope and grossular, which show consistent result with literature study on single crystals data. The correlation between the Raman mode frequencies and compositional changes along the pyrope-grossular binary suggests a two-mode behavior for Mg and Ca cations in the garnet structure. The full widths at half-maximum of selected Raman modes increase on moving away from the end members and are about double the end-member values in the mid-position, where the frequencies closely linearly change with composition. The frequencies of the translational modes of the SiO4 tetrahedron (T(SiO4)) show large deviations from linearity indicating a strong kinematic coupling with the translational modes of the Ca and Mg cations. The anomalies in T(SiO4) are linked to mixing unit cell volume, suggesting that the nonlinear mixing volume behavior along the pyrope-grossular binary is related to the resistance of the Si-O bond to expansion and compression, which is caused by substitution of Mg and Ca cations in the dodecahedral sites. Annealing temperature also shows effect on Raman mode frequencies, but the main factor controlling the changes in mode frequencies along pyrope-grossular binary is composition.

  3. Monte Carlo Evaluation of Tritium Beta Spectrum Energy Deposition in Gallium Nitride (GaN) Direct Energy Conversion Devices

    Science.gov (United States)

    2014-09-01

    Monte Carlo Evaluation of Tritium Beta Spectrum Energy Deposition in Gallium Nitride (GaN) Direct Energy Conversion Devices by Marc Litz...MD 20783-1138 ARL-TR-7082 September 2014 Monte Carlo Evaluation of Tritium Beta Spectrum Energy Deposition in Gallium Nitride (GaN...Tritium Beta Spectrum Energy Deposition in Gallium Nitride (GaN) Direct Energy Conversion Devices 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  4. KINETICS OF GRAIN-GROWTH OF YTTRIUM ALUMINUM GARNET FIBERS PREPARED BY SOL-GEL METHOD

    Directory of Open Access Journals (Sweden)

    Tan H.

    2013-12-01

    Full Text Available The yttrium aluminum garnet (YAG long fibers were prepared by the sol-gel method using aluminum chloride, aluminum powder, yttrium oxide and acetic acid as raw materials. The grain growth law is given by Dn – D0n = Kt (D0 = initial grain size, D = average grain size at time t, n = grain growth exponent and K = reaction constant. The grain growth exponent and activation energy of YAG fibers are ≈ 3 and 200 kJ/mol, respectively. The grain-growth behaviors of YAG were influenced by experimental conditions such as raw materials, initial particle size, initial particle distribution, etc.

  5. Divalent ytterbium ions in yttrium aluminum garnet and yttrium oxide ceramics

    Science.gov (United States)

    Solomonov, V. I.; Orlov, A. N.; Spirina, A. V.; Konev, S. F.; Cholakh, S. O.; Luk'yashin, K. E.

    2014-12-01

    Laser ceramics based on ytterbium-doped yttrium aluminum garnet and yttrium oxide are synthesized. The transmission, pulsed cathodoluminescence, and electron-spin resonance spectra of these ceramics at room temperature are measured and analyzed. It is shown that all the samples contain Yb2+ ions with the 4 f 136 s electronic configuration of the ground state, which manifest themselves in the form of relatively weak bands in the IR region of the optical spectra in addition to the bands of Yb3+ ions.

  6. Luminescence of spodumene and garnet crystals excited by subnanosecond and nanosecond electron beams

    Science.gov (United States)

    Tarasenko, V. F.; Solomonov, V. I.; Polisadova, E. F.; Burachenko, A. G.; Baksht, E. Kh.

    2012-05-01

    The pulsed cathode luminescence of spodumene and yttrium-aluminum garnet crystals activated by Mn2+ and Nd3+ ions, respectively, is studied. Luminescence is excited by the irradiation of the crystals by electron beams with a duration of 0.1, 0.25, 0.65, and 10 ns and a current density of ˜40 and 100 A/cm2 at an electron energy of ˜200 keV. A decrease in the electron beam duration to several tenths of a nanosecond is shown not to cause substantial changes in the excitation mechanisms of pulsed cathode luminescence and its spectrum.

  7. On the nature and origin of garnet in highly-refractory Archean lithosphere: implications for continent stabilisation

    Science.gov (United States)

    Gibson, Sally

    2014-05-01

    The nature and timescales of garnet formation in the Earth's subcontinental lithospheric mantle (SCLM) are important to our understanding of how this rigid outer shell has evolved and stabilised since the Archean. Nevertheless, the widespread occurrence of pyrope garnet in the sub-cratonic mantle remains one of the 'holy grails' of mantle petrology. The paradox is that garnet often occurs in mantle lithologies (dunites and harzburgites) which represent residues of major melting events (up to 40 %) whereas experimental studies on fertile peridotite suggest this phase should be exhausted by 10.1093/petrology/egt020 Stachel, T., Aulbach, A., Brey, G.P., Harris, J.W., Leost, I., Tappert, R. & Viljoen, K.S. (2004). The trace element composition of silicate inclusions in diamonds: a review. Lithos 77, 1-19 Lee, C.-T., Luffi, P. & Chin, E. J. (2011). Building and Destroying Continental Mantle. Annu. Rev. Earth Planet. Sci. 39, 59-90

  8. Epitaxially-grown Gallium Nitride on Gallium Oxide substrate for photon pair generation in visible and telecomm wavelengths

    KAUST Repository

    Awan, Kashif M.

    2016-08-11

    Gallium Nitride (GaN), along with other III-Nitrides, is attractive for optoelectronic and electronic applications due to its wide direct energy bandgap, as well as high thermal stability. GaN is transparent over a wide wavelength range from infra-red to the visible band, which makes it suitable for lasers and LEDs. It is also expected to be a suitable candidate for integrated nonlinear photonic circuits for a wide range of applications from all-optical signal processing to quantum computing and on-chip wavelength conversion. Despite its abundant use in commercial devices, there is still need for suitable substrate materials to reduce high densities of threading dislocations (TDs) and other structural defects like stacking faults, and grain boundaries. All these defects degrade the optical quality of the epi-grown GaN layer as they act as non-radiative recombination centers.

  9. Selective entrainment of peritectic garnet into S-type granitic magmas: Evidence from Archaean mid-crustal anatectites

    Science.gov (United States)

    Taylor, Jeanne; Stevens, Gary

    2010-12-01

    Entrainment of restite is commonly invoked to explain both the origin of relatively mafic granites and granodiorites, as well as the chemical connection between granite magmas and their sources. This concept has become linked to models for magma migration out of the source, as restite entrainment is considered to take place when diatexitic sources mobilise en masse. This is at odds with the common occurrence of relatively mafic granites as high level intrusions in the crust or their eruptive equivalents that must have formed from markedly water-undersaturated magmas that ascended through narrow conduits. We investigate pelitic migmatites from the Mkhondo Valley Metamorphic Suite (MVMS) in Swaziland, where a mid-crustal heating event produced metatexitic migmatites with minimal post-anatectic recrystallisation. In these rocks all the garnet is peritectic, having arisen through biotite fluid-absent melting, which produced garnet poikiloblasts characterised by inclusions of melt, quartz and biotite. Leucosomes that represent sites of melt transfer carry similar, smaller (typically accessory phases, while the recrystallised garnet in the larger melt-filled structures became progressively better equilibrated with these minerals. Thus, peritectic garnet in the source grew sufficiently rapidly to prevent trace element equilibrium with the bulk-rock composition, and, concurrent rapid magma segregation prevented the development of diatexitic source conditions. The segregated magma consisted of melt, the peritectic assemblage (principally garnet) and the accessory minerals monazite and zircon. These rocks illustrate that mafic granites may arise purely as mixtures of melt and the peritectic assemblage produced by the incongruent melting reaction. Importantly, under the circumstances which produced the MVMS anatectites, peritectic garnet is entrained as < 1 mm poikiloblasts, demonstrating how mafic granitic magmas can migrate out of the source without the source becoming

  10. Scandium functionalized carbon aerogel: Synthesis of nanoparticles and structure of a new ScOCl and properties of NaAlH{sub 4} as a function of pore size

    Energy Technology Data Exchange (ETDEWEB)

    Javadian, Payam; Nielsen, Thomas K. [Center for Energy Materials, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, DK-8000 Aarhus (Denmark); Ravnsbæk, Dorthe B. [Department of Material Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge 02142, MA (United States); Jepsen, Lars H. [Center for Energy Materials, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, DK-8000 Aarhus (Denmark); Polanski, Marek [Faculty of Advanced Technology and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warsaw (Poland); Plocinski, Tomasz [Faculty of Material Science and Engineering, Warsaw University of Technology, 144 Woloska Str., 02-507 Warsaw (Poland); Kunce, Izabela [Faculty of Advanced Technology and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warsaw (Poland); Besenbacher, Flemming [Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Bystrzycki, Jerzy [Faculty of Advanced Technology and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warsaw (Poland); Jensen, Torben R., E-mail: trj@chem.au.dk [Center for Energy Materials, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, DK-8000 Aarhus (Denmark)

    2015-11-15

    A new method for scandium-functionalization of carbon aerogels forming nanoparticles of a new scandiumoxochloride, ScOCl is presented. Sodium aluminiumhydride, NaAlH{sub 4}, is successfully melt infiltrated into the nano porous scaffolds with pore sizes of D{sub max}=7, 10, 13, 21, 26 and 39 nm, containing scandium based nano particles (<2.9 wt%) confirmed by elemental analysis and scanning electron microscopy. A systematic study of hydrogen storage properties of the nano composite materials is presented. An aqueous solution of ScCl{sub 3} was initially infiltrated and formed nanoconfined [Sc(OH)(H{sub 2}O){sub 5}]{sub 2}Cl{sub 4}(H{sub 2}O){sub 2}, which transforms to nanoparticles of a new scandium oxochloride, ScOCl at 192 °C and to Sc{sub 2}O{sub 3} at 420 °C. ScOCl crystallizes in an orthorhombic unit cell a=3.4409(8), b=3.9613(6) and c=8.178(2) Å, space group Pmmn, and is built from layers of [ScO{sub 4}Cl{sub 2}] octahedra forming neutral ScOCl layers. Temperature programmed desorption mass spectroscopy shows slightly improved kinetics for release of hydrogen with decreasing pore size. Continuous cycling of hydrogen release and uptake measured by the Sieverts' method reveal a larger preserved hydrogen storage capacity for scandium-functionalized aerogel with the larger pores (39 nm). - Highlights: • New synthesis approach for nanoporous Sc-functionalization carbon aerogel (Sc-CA). • The new scandium oxochloride, ScOCl, structure is obtained. • NaAlH{sub 4} nanoconfined in Sc-CA with pores ranging between 7 nm

  11. Potential use of gallium-doped phosphate-based glass material for periodontitis treatment.

    Science.gov (United States)

    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

  12. Influence of novel gallium complexes on the homeostasis of some biochemical and hematological parameters in rats.

    Science.gov (United States)

    Gârban, Gabriela; Silaghi-Dumitrescu, Radu; Ioniţă, Hortensia; Gârban, Zeno; Hădărugă, Nicoleta-Gabriela; Ghibu, George-Daniel; Baltă, Cornel; Simiz, Florin-Dan; Mitar, Carmen

    2013-12-01

    The aim of this study was to detect possible homeostasis changes in some biochemical and hematological parameters after the administration of gallium (Ga) complexes C (24) and C (85) on an experimental animal model (Wistar strain rats). In order to observe chronobiological aspects, a morning (m) and an evening (e) animal series were constituted. Further on, each series were divided into three groups: control (C), experimental I (EI), and experimental II (EII). Both Ga complexes were solubilized in a carrier solution containing polyethylene glycol (PEG) 400, water, and ethanol. Animals of the C groups received the carrier solution by intraperitoneal injection, those from the EI groups received the solubilized C(24) gallium complex, and those of the EII groups received the solubilized C(85) gallium complex. At the end of the experiment, blood and tissue samples were taken and the following parameters were determined: serum concentration of the nonprotein nitrogenous compounds (uric acid, creatinine, and blood urea nitrogen), hematological parameters (erythrocytes, hemoglobin, leukocytes, and platelets), and the kidney tissue concentration of three essential trace elements (Fe, Cu, and Zn). With the exception of uric acid, the results revealed increased concentrations of the nonprotein nitrogenous compounds both in the morning and in the evening experimental groups. Hematological data showed increased levels of erythrocytes, hemoglobin, and leukocytes and decreased platelet levels in the experimental group given the C(24) gallium complex in the morning (EI-m) group; increased levels of leukocytes and decreased levels of the other parameters in the experimental group given the C(24) gallium complex in the evening (EI-e) group; and increased levels of all hematological parameters in the experimental groups receiving the C(85) gallium complex in the morning (EII-m) group and in the evening (EII-e) group. Decreased kidney tissue concentrations of metals were found in all

  13. Direct Comparison of Detrital Garnet, Monazite, and Zircon Ages from a Southern Appalachian Tributary System for the French Broad River, North Carolina, USA

    Science.gov (United States)

    Maneiro, K. A.; Baxter, E. F.; Samson, S. D.; Marschall, H.

    2016-12-01

    Nineteen detrital garnet ages from a tributary draining into the French Broad River of North Carolina represent the first full-scale deployment of a new detrital garnet geochronometer. Under the new geochronometer, inclusions within the garnet serve as a proxy for the original source rock and eliminate required assumption of a single source for detritus. Additionally, method development has advanced techniques for small sample Nd and Sm analysis by thermal ionization mass spectrometry (TIMS), allowing for Sm-Nd analysis of single detrital garnet grains for the first time. This is also the first dataset allowing direct comparison of detrital garnet, monazite, and zircon. The three proximate tributaries sampled drain a limited source lithology, and prior studies provide detrital monazite and zircon ages (e.g. Hietpas et al., 2010, Geology; Moecher et al., 2011, Geosphere). The weighted average age for tributary detrital monazite is 460.9 ± 2.5 Ma (95% confidence). Zircon cores failed to record Paleozoic metamorphism, while zircon rims gave a weighted average age of 443.5 ± 8.7 Ma (95% confidence). The tributary system is garnet-bearing, with garnet grains exceeding the current minimum volume required for single grain analysis (≥ 0.4 mm max. diameter). Previously reported initial ages from the garnet grains (Maneiro-Eccles, 2015, Goldschmidt) have been updated to include blank correction accounting for extremely small Nd loads; clean garnet analyses contain 17-445 pg Nd and repeat blanks indicate contribution of 4.31 ± 0.59 pg Nd. The resulting weighted average age for garnet is 438.8 ± 8.1 Ma (95% confidence). The weighted average ages for zircon rims and garnet overlap within error, while the monazite age is older (22.1 ± 8.5 Myr older than garnet, 17.4 ± 9.1 Myr older than zircon). Age variance between minerals could be attributed to monazite sampling bias, limited sample size, and either influence by a secondary tectonic event (e.g. the Cherokee Orogeny

  14. IBA investigations of loose garnets from Pietroasa, Apahida and Cluj-Someşeni treasures (5th century AD)

    Science.gov (United States)

    Bugoi, R.; Oanţă-Marghitu, R.; Calligaro, T.

    2016-03-01

    This paper reports the archaeometric investigations of 418 loose garnets from Pietroasa and Cluj-Someşeni treasures and Apahida II and III princely grave inventories (5th century AD). The chemical composition of the gems was determined by external beam micro-PIXE technique at the AGLAE accelerator of C2RMF, Paris, France. Complementary observations made by Optical Microscopy revealed details on the gemstones cutting and polishing and permitted to identify certain mineral inclusions. The compositional results evidenced several types of garnets from the pyralspite series, suggesting distinct provenances for these Early Medieval gems.

  15. IBA investigations of loose garnets from Pietroasa, Apahida and Cluj-Someşeni treasures (5th century AD)

    Energy Technology Data Exchange (ETDEWEB)

    Bugoi, R., E-mail: bugoi@nipne.ro [Horia Hulubei National Institute for Nuclear Physics and Engineering, Măgurele 077125 (Romania); Oanţă-Marghitu, R., E-mail: rodicamarghitu@yahoo.com [Muzeul Naţional de Istorie a României, Bucureşti 030026 (Romania); Calligaro, T., E-mail: thomas.calligaro@culture.gouv.fr [Centre de Recherche et de Restauration des Musées de France, C2RMF, Palais du Louvre – Porte des Lions, 75001 Paris (France); PSL Research University, Chimie ParisTech – CNRS, Institut de Recherche Chimie Paris, UMR8247, 75005 Paris (France)

    2016-03-15

    This paper reports the archaeometric investigations of 418 loose garnets from Pietroasa and Cluj-Someşeni treasures and Apahida II and III princely grave inventories (5th century AD). The chemical composition of the gems was determined by external beam micro-PIXE technique at the AGLAE accelerator of C2RMF, Paris, France. Complementary observations made by Optical Microscopy revealed details on the gemstones cutting and polishing and permitted to identify certain mineral inclusions. The compositional results evidenced several types of garnets from the pyralspite series, suggesting distinct provenances for these Early Medieval gems.

  16. Yttrium aluminium garnet under pressure: Structural, elastic, and vibrational properties from ab initio studies

    Energy Technology Data Exchange (ETDEWEB)

    Monteseguro, V. [Departamento de Física and MALTA Consolider Team, Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Santa Cruz de Tenerife (Spain); Rodríguez-Hernández, P.; Muñoz, A., E-mail: amunoz@ull.es [Departamento de Física and MALTA Consolider Team, Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Santa Cruz de Tenerife (Spain); Instituto de Materiales y Nanotecnología. Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Santa Cruz de Tenerife (Spain)

    2015-12-28

    The structural, elastic, and vibrational properties of yttrium aluminum garnet Y{sub 3}Al{sub 5}O{sub 12} are studied under high pressure by ab initio calculations in the framework of the density functional theory. The calculated ground state properties are in good agreement with the available experimental data. Pressure dependences of bond length and bulk moduli of the constituent polyhedra are reported. The evolution of the elastic constants and the major elastic properties, Young and shear modulus, Poisson's ratios, and Zener anisotropy ratio, are described. The mechanical stability is analyzed, on the light of “Born generalized stability criteria,” showing that the garnet is mechanically unstable above 116 GPa. Symmetries, frequencies, and pressure coefficients of the Raman-active modes are discussed on the basis of the calculated total and partial phonon density of states, which reflect the dynamical contribution of each atom. The relations between the phonon modes of Y{sub 3}Al{sub 5}O{sub 12} and the internal and external molecular modes of the different polyhedra are discussed. Infrared-active modes, as well as the silent modes, and their pressure dependence are also investigated. No dynamical instabilities were found below 116 GPa.

  17. Characterization of Erbium Substituted Yttrium Iron Garnet Films Prepared by Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Ramadan E. Shaiboub

    2014-01-01

    Full Text Available Yttrium iron garnet (YIG thin films substituted erbium ions (Er+3 Er0.4Y2.6Fe5O12 films were prepared by a sol-gel method at different temperatures which varied from 800 to 1000°C for 2 hours in air. Magnetic and microstructural properties of the films were characterized with X-ray diffraction (XRD, the field emission scanning electron microscopy (FESEM, and vibrating sample magnetometer (VSM. The XRD patterns of the sample have only peaks of the garnet structure. The lattice constants decrease, while the particle size increases from 51 to 85 nm as the annealing temperature increases with average in thickness of 300 nm. The saturation magnetization and the coercivity of the samples increased from 26 (emu/cc and 28 Oe for the film annealed at 800°C to 76 (emu/cc and 45 Oe for film annealed at 1000°C, respectively.

  18. The first discovery of Hadean zircon in garnet granulites from the Sutam River (Aldan Shield)

    Science.gov (United States)

    Glukhovskii, M. Z.; Kuz'min, M. I.; Bayanova, T. B.; Lyalina, L. M.; Makrygina, V. A.; Shcherbakova, T. F.

    2017-09-01

    For the first time in Russia, a Hadean zircon grain with an age of 3.94 Ga (ID-TIMS) has been discovered in high-aluminous garnet granulites of the Aldan Shield among the U-Pb zircons with an age from 1.92 Ga. In this connection, the problems of its parental source, the petrogenesis of granulites that captured this zircon, and the mechanism of occurrence of these deep rocks in the upper horizons of the crust have been solved. The comparison of the geochemistry of garnet granulites and the middle crust has shown that the granulites are enriched in the entire range of rare-earth elements (except for the Eu minimum), as well as in Al2O3, U, and Th and are depleted in the most mobile elements (Na, Ca, Sr). In the upper part of the allitic weathering zone of the middle crust, which formed under conditions of arid climate, this zircon grain was originated from the weathered granites from the middle crust. In the latter case, they were empleced discretely in the upper granite-gneiss crust under high pressure conditions (the rutile age is 1.83-1.82 Ga). The zircon with an age of 3.94 Ga is comparable to the Hadean zircons from orthogneisses of the Acasta region (Canadian Shield, 4.03-3.94 Ga).

  19. Scintillating Screens Based on the Single Crystalline Films of Multicomponent Garnets: New Achievements and Possibilities

    Science.gov (United States)

    Zorenko, Yuriy; Gorbenko, Vitalii; Zorenko, Tetiana; Paprocki, Kazimierz; Nikl, Martin; Mares, Jiri A.; Bilski, Pawel; Twardak, Anna; Sidletskiy, Oleg; Gerasymov, Iaroslav; Grinyov, Boris; Fedorov, Alexandr

    2016-04-01

    The paper is dedicated to development of the novel scintillating screens based on single crystalline films (SCF) of Ce doped Lu3 - xTbxAl5 - yGayO12 multicomponent garnets at x = 2 - 3 and y = 0 - 2.5 onto Y3Al5O12 (YAG) and Gd3Al2.5Ga2.5O12 (GAGG) substrates using the liquid phase epitaxy (LPE) method. We report the optimized content and high scintillation figure of merit of SCF of these garnets grown by the LPE method with using PbO based flux. Namely, the Tb3Al2.5Ga2.5O12:Ce SCFs possess the highest values of light yield (LY) compared to all earlier investigated SCF samples, with their LY exceeding by 2.35 and 1.15 times the LY values for YAG:Ce and LuAG:Ce SCF scintillators, respectively. The SCFs of the mentioned compounds show very lower thermoluminescence in the above room temperature range and relatively fast scintillation decay.

  20. Physical and microwave characteristics of Gd-doping yttrium iron garnet (YIG)

    Science.gov (United States)

    Tai, M. F.; Wang, K. Z.; Hong, L. R.; Wu, C. J.; Lin, L. C.; Ku, H. C.; Liu, S. Z.; Kwo, K. M.

    2010-03-01

    Ferrimagnetic insulating yttrium iron garnet (YIG) are widely used in microwave devices due to their unique magnetic, electrical and microwave properties. The substitution of rare earth ion for the Y^3+ ion can modulate or improve its high-frequency properties for microwave application. We prepared a serial of single-phased polycrystalline Y3-xGdxFe5O12 garnet samples with x = -- 3.0 by the conventional ceramic technique. The refinement of X-ray diffraction patterns of the samples shows them to crystallize in a centrosymmetrically cubic structure with a Ia3d space group. Both the lattice constant and dc saturation magnetization at room temperature decrease with increasing Gd^3+ We also measured the low- and high-frequency dielectric constant and tangent loss. As well, the spin wave line width δHk regarding the ferromagnetic resonance behavior is on progress. These results are important to develop high-power circulators and isolators in microwave range.

  1. Synthesis and characterization of yttrium iron garnet (YIG nanoparticles - Microwave material

    Directory of Open Access Journals (Sweden)

    Vinay Sharma

    2017-05-01

    Full Text Available Magnetic Yttrium Iron Garnet (YIG nanoparticles (NPs were prepared by sol–gel (SG and solid-state (SS reaction methods to elucidate the nanoscale size on the magnetic behavior of NPs. It is found that YIG prepared by these two methods are different in many ways. The average NP sizes prepared by SG and SS methods were calculated by Scherrer formula from XRD data. SEM images show the change in grain size for both types of NPs. The sintering temperature required to form pure garnet phase is 750°C for SG and 1000°C for SS NPs. The saturation magnetizations (Ms were 1070 Oe for SG and 1125 Oe for SS NPs, respectively. The coercivity (Hc of SS NPs are twice larger than SG NPs. This is due to the larger crystal sizes of the SS NPs, hence more crystal boundaries. Dynamic properties were studied by ferromagnetic resonance (FMR technique in field-sweep and frequency-sweep mode at different fixed frequencies and at different fixed magnetic fields, respectively. Resonance field (Hr observed to increase linearly with frequency both for SS and SG NPs. The stop-band bandwidth (frequency linewidth is narrower for SG NPs in comparison to SS NPs. Microwave absorption property make this material as a strong candidate for microwave device applications.

  2. Garnet-free optical circulators monolithically integrated on spatially modified III-V quantum wells

    CERN Document Server

    Aleahmad, Parinaz; Christodoulides, Demetrios; LiKamWa, Patrick

    2016-01-01

    Optical circulators are indispensable components in photonic networks that are aimed to route information in a unidirectional way among their N-ports1,2. In general, these devices rely on magneto-optical garnets3 with appreciable Verdet constants that are utilized in conjunction with other elements like permanent magnets, wave-plates, birefringent crystals and/or beam splitters. Consequently, these arrangements are typically bulky and hence not conducive to on-chip photonic integration4-6. Of interest would be to devise strategies through which miniaturized optical circulators can be monolithically fabricated on light-emitting semiconductor platforms by solely relying on physical properties that are indigenous to the material itself. By exploiting the interplay between non-Hermiticity and nonlinearity, here we demonstrate a new class of chip-scale circulators on spatially modified III-V quantum well systems. These garnet-free unidirectional structures are broadband (over 2.5 THz) at 1550 nm, effectively loss-...

  3. Gallium-containing phospho-silicate glasses: synthesis and in vitro bioactivity.

    Science.gov (United States)

    Franchini, Mirco; Lusvardi, Gigliola; Malavasi, Gianluca; Menabue, Ledi

    2012-08-01

    A series of Ga-containing phospho-silicate glasses based on Bioglass 45S5, having molar formula 46.2SiO2·24.3Na2O·26.9CaO·2.6P2O5·xGa2O3 (x=1.0, 1.6, 3.5), were prepared by fusion method. The reference Bioglass 45S5 without gallium was also prepared. The synthesized glasses were immersed in simulated body fluid (SBF) for 30 days in order to observe ion release and hydroxyapatite (HA) formation. All Ga-containing glasses maintain the ability of HA formation as indicated by main X-ray diffractometric peaks and/or electronic scanning microscopy results. HA layer was formed after 1 day of SBF soaking in 45S5 glass containing up to 1.6% Ga2O3 content. Moreover, gallium released by the glasses was found to be partially precipitated on the glass surface as gallium phosphate. Further increase in gallium content reduced the ion release in SBF. The maximum of Ga(3+) concentration measured in solution is ~6 ppm determined for 3.5% Ga2O3 content. This amount is about half of the toxic level (14 ppm) of gallium and the glasses release gallium till 30 days of immersion in SBF. Considering the above results, the studied materials can be proposed as bioactive glasses with additional antimicrobial effect of gallium having no toxic outcome. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Antitumor efficacy and tolerability of systemically administered gallium acetylacetonate-loaded gelucire-stabilized nanoparticles.

    Science.gov (United States)

    Wehrung, Daniel; Bi, Lipeng; Geldenhuys, Werner J; Oyewumi, Moses O

    2013-06-01

    The widespread clinical success with most gallium compounds in cancer therapy is markedly hampered by lack of tumor specific accumulation, poor tumor permeability and undesirable toxicity to healthy tissues. The aim of this work was to investigate for the first time antitumor mechanism of a new gallium compound (gallium acetylacetonate; GaAcAc) while assessing effectiveness of gelucire-stabilized nanoparticles (NPs) for potential application in gallium-based lung cancer therapy. NPs loaded with GaAcAc (Ga-NPs) were prepared using mixtures of cetyl alcohol with Gelucire 44/14 (Ga-NP-1) or Gelucire 53/13 (Ga-NP-2) as matrix materials. Of special note from this work is the direct evidence of involvement of microtubule disruption in antitumor effects of GaAcAc on human lung adenocarcinoma (A549). In-vivo tolerability studies were based on plasma ALT, creatinine levels and histopathological examination of tissues. The superior in-vivo antitumor efficacy of Ga-NPs over GaAcAc was depicted in marked reduction of tumor weight and tumor volume as well as histological assessment of excised tumors. Compared to free GaAcAc, Ga-NPs showed a 3-fold increase in tumor-to-blood gallium concentrations with minimized overall exposure to healthy tissues. Overall, enhancement of antitumor effects of GaAcAc by gelucire-stabilized NPs coupled with reduced exposure of healthy tissues to gallium would likely ensure desired therapeutic outcomes and safety of gallium-based cancer treatment.

  5. In vitro bio-functionality of gallium nitride sensors for radiation biophysics.

    Science.gov (United States)

    Hofstetter, Markus; Howgate, John; Schmid, Martin; Schoell, Sebastian; Sachsenhauser, Matthias; Adigüzel, Denis; Stutzmann, Martin; Sharp, Ian D; Thalhammer, Stefan

    2012-07-27

    There is an increasing interest in the integration of hybrid bio-semiconductor systems for the non-invasive evaluation of physiological parameters. High quality gallium nitride and its alloys show promising characteristics to monitor cellular parameters. Nevertheless, such applications not only request appropriate sensing capabilities but also the biocompatibility and especially the biofunctionality of materials. Here we show extensive biocompatibility studies of gallium nitride and, for the first time, a biofunctionality assay using ionizing radiation. Analytical sensor devices are used in medical settings, as well as for cell- and tissue engineering. Within these fields, semiconductor devices have increasingly been applied for online biosensing on a cellular and tissue level. Integration of advanced materials such as gallium nitride into these systems has the potential to increase the range of applicability for a multitude of test devices and greatly enhance sensitivity and functionality. However, for such applications it is necessary to optimize cell-surface interactions and to verify the biocompatibility of the semiconductor. In this work, we present studies of mouse fibroblast cell activity grown on gallium nitride surfaces after applying external noxa. Cell-semiconductor hybrids were irradiated with X-rays at air kerma doses up to 250 mGy and the DNA repair dynamics, cell proliferation, and cell growth dynamics of adherent cells were compared to control samples. The impact of ionizing radiation on DNA, along with the associated cellular repair mechanisms, is well characterized and serves as a reference tool for evaluation of substrate effects. The results indicate that gallium nitride does not require specific surface treatments to ensure biocompatibility and suggest that cell signaling is not affected by micro-environmental alterations arising from gallium nitride-cell interactions. The observation that gallium nitride provides no bio-functional influence on

  6. Local stress distribution around garnet inclusions during hydration of granulite in the Bergen Arcs, Norway

    Science.gov (United States)

    Centrella, Stephen; Vrijmoed, Johannes C.; Putnis, Andrew; Austrheim, Håkon

    2017-04-01

    The importance of heterogeneous stress and pressure distribution within a rock has been established over the last decades (see review in Tajčmanová et al., 2015). During a hydration reaction, depending on whether the system is open to mass transfer, the volume changes of the reaction may be accommodated by removing material into the fluid phase that leaves the system (Centrella et al., 2015; Centrella et al., 2016). The magnitudes and the spatial distribution of stress and pressure that evolve during such processes is largely unknown. We present here a natural example where a granulite is hydrated at amphibolite facies conditions from the Bergen Arcs in Norway. Granulitic garnet is associated with kyanite and quartz on one side, and amphibole-biotite on the other side. The first couple replaces the plagioclase of the granulite matrix whereas the second replaces the garnet. We use electron probe microanalysis (EPMA) and X-ray mapping to investigate the spatial and possible temporal relationships between these two parageneses. Gresens' analysis has been used to determine the mass balance and the local volume changes associated with the two reactions. The reaction to kyanite+quartz induces a loss in volume compared to the original plagioclase whereas the second reaction amphibole+biotite gains volume compared to the original garnet. The specific mass evolution associated with both reactions suggests a local mass balance probably associated with a single hydration event. Using the methodology of Vrijmoed & Podladchikov (2015) we test whether the microstructure may be partly related to the local stress heterogeneity around the garnet inclusion. We evaluate the phase assemblage and distribution at chemical equilibrium under a given input pressure field that can be computed with the Thermolab software. By varying the input pressure field using the Finite Element Method and comparing the resulting equilibrium assemblage to the real data an estimate of the local stress

  7. Large discrepancies between garnet Lu-Hf and Sm-Nd isochron ages: the problem of inherited Hf

    Science.gov (United States)

    Raimondo, Tom; Payne, Justin; Hand, Martin; Clark, Chris; Anczkiewicz, Robert

    2017-04-01

    A commonly observed phenomenon in garnet geochronology is that Lu-Hf isochron ages are consistently older than Sm-Nd ages from the same sample, a relationship explained by differences in closure temperature and REE zoning that are then used as the basis for constraining mineral growth and/or cooling rates. We report Lu-Hf and Sm-Nd age discrepancies of up to 40 Myr from three samples of garnet-chlorite-magnetite schist from the Walter-Outalpa Shear Zone, Curnamona Province, South Australia. Lu-Hf and Sm-Nd isochron ages vary between 531-515 Ma and 500-479 Ma, respectively, spanning the entire duration of the 514-490 Ma Delamerian Orogeny. U-Pb monazite ages from matrix-hosted grains are within error of the youngest Sm-Nd ages (c. 480 Ma), whereas monazite inclusions in garnet return age estimates coeval with the oldest Sm-Nd age (c. 500 Ma). LA-ICP-MS trace element mapping reveals that Nd is strongly partitioned into garnet rims for samples with the youngest ages, suggesting that REE zoning biases these estimates towards the latter stages of garnet growth. Conversely, Lu-Hf ages largely reflect Hf distributions that are strongly concentrated in core domains, most likely representing the earlier timing of garnet nucleation in prograde zoned grains. However, all samples contain zircon present either as a matrix accessory phase or as inclusions in garnet, often as micron-scale grains difficult to detect without detailed SEM/LA-ICP-MS imaging. This calls into question the implicit assumption that the Lu-Hf isochron has an initial gradient of zero, i.e. that the 176Hf/177Hf ratio of newly grown garnet is in equilibrium with the whole rock composition. We demonstrate that this assumption is invalid in circumstances where the whole-rock Hf budget is dominated by minerals that do not enter diffusional exchange with garnet, a common occurrence in metapelitic and felsic rocks that contain significant amounts of inherited zircon. Such problems are exacerbated by mineral

  8. Punctuated HT/UHT metamorphism during prolonged Archean orogenesis in the Pikwitonei Granulite Domain revealed by garnet petrochronology

    Science.gov (United States)

    Dragovic, Besim; Guevara, Victor; Caddick, Mark; Couëslan, Chris; Baxter, Ethan

    2017-04-01

    Fundamental to every modern continent's early (Archean) history is the generation of high temperature conditions required to produce the dense, strong, relatively anhydrous rocks that comprise most of Earth's stable cratonic crust. While the thermal gradients supported in Archean terranes are better understood, the timescales over which these conditions occur are more enigmatic. Garnet petrochronology allows for the interrogation of a semi-continuous record of these tectonometamorphic conditions, by linking pressure-temperature-fluid conditions (using phase equilibria modeling, trace element thermometry, stable isotope geochemistry) to a precise chronologic/chronometric record (e.g. high-precision Sm-Nd geochronology, geospeedometry of major and trace element diffusion profiles). Here, we utilize techniques from this burgeoning field of study to elucidate the rates and conditions of high temperature/ultra-high temperature (HT/UHT) metamorphism in the 2.7 Ga Pikwitonei Granulite Domain (PGD). The PGD represents over 150,000 km2 of dominantly granulite-facies metamorphic rocks situated at the NW edge of the Superior Province. Peak temperatures in the region range from 760°C in the southernmost part of the PGD, to 900-960˚C in the central/western PGD ( 40-60 km apart). Previous studies have suggested that metamorphism was long-lived in the region, occurring over 100 Ma, from 2.71-2.60 Ga [1, 2, 3]. High-precision garnet geochronology on microsampled garnets provides a detailed growth history of several lithologies across the region. Where necessary, bulk garnet analysis (i.e. dating based upon multiple whole garnet crystals rather than portions thereof) was also performed. While cooling from HT/UHT will result in some degree of intra-mineral age resetting, a detailed isotopic study of a range of large garnet porphyroblasts from the PGD (those which would be variably reset depending on peak T, grain size, and initial cooling rate) can retain information about both

  9. Investigating the effect of gallium curcumin and gallium diacetylcurcumin complexes on the structure, function and oxidative stability of the peroxidase enzyme and their anticancer and antibacterial activities.

    Science.gov (United States)

    Jahangoshaei, Parisa; Hassani, Leila; Mohammadi, Fakhrossadat; Hamidi, Akram; Mohammadi, Khosro

    2015-10-01

    Curcumin has a wide spectrum of biological and pharmacological activities including anti-inflammatory, antioxidant, antiproliferative, antimicrobial and anticancer activities. Complexation of curcumin with metals has gained attention in recent years for improvement of its stability. In this study, the effect of gallium curcumin and gallium diacetylcurcumin on the structure, function and oxidative stability of horseradish peroxidase (HRP) enzyme were evaluated by spectroscopic techniques. In addition to the enzymatic investigation, the cytotoxic effect of the complexes was assessed on bladder, MCF-7 breast cancer and LNCaP prostate carcinoma cell lines by MTT assay. Furthermore, antibacterial activity of the complexes against S. aureus and E. coli was explored by dilution test method. The results showed that the complexes improve activity of HRP and also increase its tolerance against the oxidative condition. After addition of the complexes, affinity of HRP for hydrogen peroxide substrate decreases, while the affinity increases for phenol substrate. Circular dichroism, intrinsic and synchronous fluorescence spectra showed that the enzyme structure around the catalytic heme group becomes less compact and also the distance between the heme group and tryptophan residues increases due to binding of the complexes to HRP. On the whole, it can be concluded that the change in the enzyme structure upon binding to the gallium curcumin and gallium diacetylcurcumin complexes results in an increase in the antioxidant efficiency and activity of the peroxidise enzyme. The result of anticancer and antibacterial activities suggested that the complexes exhibit the potential for cancer treatment, but they have no significant antibacterial activity.

  10. Hydride vapor phase epitaxy growth of GaN, InGaN, ScN, and ScAIN

    NARCIS (Netherlands)

    Bohnen, T.

    2010-01-01

    Chemical vapor deposition (CVD); hydride vapor phase epitaxy (HVPE); gallium nitride (GaN); indium gallium nitride (InGaN); scandium nitride (ScN); scandium aluminum nitride (ScAlN); semiconductors; thin films; nanowires; III nitrides; crystal growth - We studied the HVPE growth of different III

  11. Aluminum-Scandium Alloys: Material Characterization, Friction Stir Welding, and Compatibility With Hydrogen Peroxide (MSFC Center Director's Discretionary Fund Final Report, Proj. No. 04-14)

    Science.gov (United States)

    Lee, J. A.; Chen, P. S.

    2004-01-01

    This Technical Memorandum describes the development of several high-strength aluminum (Al) alloys that are compatible with hydrogen peroxide (H2O2) propellant for NASA Hypersonic-X (Hyper-X) vehicles fuel tanks and structures. The yield strengths for some of these Al-magnesium-based alloys are more than 3 times stronger than the conventional 5254-H112 Al alloy, while maintaining excellent H2O2 compatibility similar to class 1 5254 alloy. The alloy development strategy is to add scandium, zirconium, and other transitional metals with unique electrochemical properties, which will not act as catalysts, to decompose the highly concentrated 90 percent H2O2. Test coupons are machined from sheet metals for H2O2 long-term exposure testing and mechanical properties testing. In addition, the ability to weld the new alloys using friction stir welding has also been explored. The new high-strength alloys could represent an enabling material technology for Hyper-X vehicles, where flight weight reduction is a critical requirement.

  12. Impact of layer and substrate properties on the surface acoustic wave velocity in scandium doped aluminum nitride based SAW devices on sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Gillinger, M., E-mail: manuel.gillinger@tuwien.ac.at; Knobloch, T.; Schneider, M.; Schmid, U. [Institute of Sensor and Actuator Systems, TU Wien, 1040 Vienna (Austria); Shaposhnikov, K.; Kaltenbacher, M. [Institute of Mechanics and Mechatronics, TU Wien, 1040 Vienna (Austria)

    2016-06-06

    This paper investigates the performance of surface acoustic wave (SAW) devices consisting of reactively sputter deposited scandium doped aluminum nitride (Sc{sub x}Al{sub 1-x}N) thin films as piezoelectric layers on sapphire substrates for wireless sensor or for RF-MEMS applications. To investigate the influence of piezoelectric film thickness on the device properties, samples with thickness ranging from 500 nm up to 3000 nm are fabricated. S{sub 21} measurements and simulations demonstrate that the phase velocity is predominantly influenced by the mass density of the electrode material rather than by the thickness of the piezoelectric film. Additionally, the wave propagation direction is varied by rotating the interdigital transducer structures with respect to the crystal orientation of the substrate. The phase velocity is about 2.5% higher for a-direction compared to m-direction of the sapphire substrate, which is in excellent agreement with the difference in the anisotropic Young's modulus of the substrate corresponding to these directions.

  13. Gallium isotope fractionation during Ga adsorption on calcite and goethite

    Science.gov (United States)

    Yuan, Wei; Saldi, Giuseppe D.; Chen, JiuBin; Vetuschi Zuccolini, Marino; Birck, Jean-Louis; Liu, Yujie; Schott, Jacques

    2018-02-01

    Gallium (Ga) isotopic fractionation during its adsorption on calcite and goethite was investigated at 20 °C as a function of the solution pH, Ga aqueous concentration and speciation, and the solid to solution ratio. In all experiments Ga was found to be enriched in light isotopes at the solid surface with isotope fractionation △71Gasolid-solution up to -1.27‰ and -0.89‰ for calcite and goethite, respectively. Comparison of Ga isotopic data of this study with predictions for 'closed system' equilibrium and 'Rayleigh fractionation' models indicates that the experimental data are consistent with a 'closed system' equilibrium exchange between the fluid and the solid. The results of this study can be interpreted based on Ga aqueous speciation and the structure of Ga complexes formed at the solid surfaces. For calcite, Ga isotope fractionation is mainly triggered by increased Ga coordination and Ga-O bond length, which vary respectively from 4 and 1.84 Å in Ga(OH)4- to 6 and 1.94 Å in the >Ca-O-GaOH(OH2)4+ surface complex. For goethite, despite the formation of Ga hexa-coordinated >FeOGa(OH)20 surface complexes (Ga-O distances of 1.96-1.98 Å) both at acid and alkaline pH, a similar extent of isotope fractionation was found at acid and alkaline pH, suggesting that Ga(OH)4- is preferentially adsorbed on goethite for all investigated pH conditions. In addition, the observed decrease of Ga isotope fractionation magnitude observed with increasing Ga surface coverage for both calcite and goethite is likely related to the formation of Ga surface polymers and/or hydroxides with reduced Ga-O distances. This first study of Ga isotope fractionation during solid-fluid interactions suggests that the adsorption of Ga by oxides, carbonates or clay minerals could yield significant Ga isotope fractionation between secondary minerals and surficial fluids including seawater. Ga isotopes thus should help to better characterize the surficial biogeochemical cycles of gallium and its

  14. Investigating change of properties in gallium ion irradiation patterned single-layer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Quan, E-mail: wangq@mail.ujs.edu.cn [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (China); Dong, Jinyao; Bai, Bing [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Xie, Guoxin [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

    2016-10-14

    Besides its excellent physical properties, graphene promises to play a significant role in electronics with superior properties, which requires patterning of graphene for device integration. Here, we presented the changes in properties of single-layer graphene before and after patterning using gallium ion beam. Combined with Raman spectra of graphene, the scanning capacitance microscopy (SCM) image confirmed that a metal–insulator transition occurred after large doses of gallium ion irradiation. The changes in work function and Raman spectra of graphene indicated that the defect density increased as increasing the dose and a structural transition occurred during gallium ion irradiation. The patterning width of graphene presented an increasing trend due to the scattering influence of the impurities and the substrate. - Highlights: • The scanning capacitance microscopy image confirmed a metal–insulator transition occurred after large doses of gallium ion irradiation. • The changes indicated the defect density increased as increasing the dose and a structural transition occurred during gallium ion irradiation. • The patterning width of graphene presented a increasing trend due to the scattering influence of the impurities and the substrate.

  15. Bone marrow accumulation in gallium scintigraphy in patients with adult still's disease

    Energy Technology Data Exchange (ETDEWEB)

    Kanegae, Futoshi; Tada, Yoshifumi; Ohta, Akihide; Ushiyama, Osamu; Suzuki; Noriaki; Koarada, Syuichi; Haruta, Yoshio; Yoshikai, Tomonori; Nagasawa, Kohei [Saga Medical School (Japan)

    2002-12-01

    We investigated the features and the usefulness of gallium scintigraphy in the diagnosis and the assessment of Adult Still's disease (ASD) by retrospective case review. Gallium scintigraphy have been done for 11 cases of ASD (3 males and 8 females) and 4 females were positive. Among these, 67 Ga-citrate was accumulated to the bone marrow in all 4 cases and to the major joints in 2 cases. Positive cases were rather serious and administered more immunosuppressants than negative cases. In order to characterize gallium scintigraphy findings of ASD, i.e. bone marrow accumulation, we analyzed 130 cases of collagen vascular disease. Although 101 cases (77.7%) were positive, only 7 cases (5.4%) showed the accumulation of {sup 67}Ga-citrate to the bone marrow. These include 3 cases with ASD, and 1 case with systemic lupus erythematosus, polyarteritis nodosa, Wegener's granulomatosis and Sjogren's syndrome. We also accumulated 18 patients who exhibited bone marrow accumulation of {sup 69}Ga-citrate, and found that 7 patients had collagen vascular and their related diseases. In conclusion, bone marrow accumulation in gallium scintigraphy is a specific feature of collagen vascular diseases, especially ASD, and it is suggested that cases with positive gallium scintigraphy in ASD can be serious and resistant to treatment. (author)

  16. The global anthropogenic gallium system: determinants of demand, supply and efficiency improvements.

    Science.gov (United States)

    Løvik, Amund N; Restrepo, Eliette; Müller, Daniel B

    2015-05-05

    Gallium has been labeled as a critical metal due to rapidly growing consumption, importance for low-carbon technologies such as solid state lighting and photovoltaics, and being produced only as a byproduct of other metals (mainly aluminum). The global system of primary production, manufacturing, use and recycling has not yet been described or quantified in the literature. This prevents predictions of future demand, supply and possibilities for efficiency improvements on a system level. We present a description of the global anthropogenic gallium system and quantify the system using a combination of statistical data and technical parameters. We estimated that gallium was produced from 8 to 21% of alumina plants in 2011. The most important applications of gallium are NdFeB permanent magnets, integrated circuits and GaAs/GaP-based light-emitting diodes, demanding 22-37%, 16-27%, and 11-21% of primary metal production, respectively. GaN-based light-emitting diodes and photovoltaics are less important, both with 2-6%. We estimated that 120-170 tons, corresponding to 40-60% of primary production, ended up in production wastes that were either disposed of or stored. While demand for gallium is expected to rise in the future, our results indicated that it is possible to increase primary production substantially with conventional technology, as well as improve the system-wide material efficiency.

  17. Cell behavior on gallium nitride surfaces: peptide affinity attachment versus covalent functionalization.

    Science.gov (United States)

    Foster, Corey M; Collazo, Ramon; Sitar, Zlatko; Ivanisevic, Albena

    2013-07-02

    Gallium nitride is a wide band gap semiconductor that demonstrates a unique set of optical and electrical properties as well as aqueous stability and biocompatibility. This combination of properties makes gallium nitride a strong candidate for use in chemical and biological applications such as sensors and neural interfaces. Molecular modification can be used to enhance the functionality and properties of the gallium nitride surface. Here, gallium nitride surfaces were functionalized with a PC12 cell adhesion promoting peptide using covalent and affinity driven attachment methods. The covalent scheme proceeded by Grignard reaction and olefin metathesis while the affinity driven scheme utilized the recognition peptide isolated through phage display. This study shows that the method of attaching the adhesion peptide influences PC12 cell adhesion and differentiation as measured by cell density and morphological analysis. Covalent attachment promoted monolayer and dispersed cell adhesion while affinity driven attachment promoted multilayer cell agglomeration. Higher cell density was observed on surfaces modified using the recognition peptide. The results suggest that the covalent and affinity driven attachment methods are both suitable for promoting PC12 cell adhesion to the gallium nitride surface, though each method may be preferentially suited for distinct applications.

  18. Biofilm formation on titanium implants counteracted by grafting gallium and silver ions.

    Science.gov (United States)

    Cochis, Andrea; Azzimonti, Barbara; Della Valle, Cinzia; Chiesa, Roberto; Arciola, Carla Renata; Rimondini, Lia

    2015-03-01

    Biofilm-associated infections remain the leading cause of implant failure. Thanks to its established biocompatibility and biomechanical properties, titanium has become one of the most widely used materials for bone implants. Engineered surface modifications of titanium able to thwart biofilm formation while endowing a safe anchorage to eukaryotic cells are being progressively developed. Here surfaces of disks of commercial grade 2 titanium for bone implant were grafted with gallium and silver ions by anodic spark deposition. Scanning electron microscopy of the surface morphology and energy dispersive X-ray spectroscopy were used for characterization. Gallium-grafted titanium was evaluated in comparison with silver-grafted titanium for both in vivo and in vitro antibiofilm properties and for in vitro compatibility with human primary gingival fibroblasts. Surface-modified materials showed: (i) homogeneous porous morphology, with pores of micrometric size; (ii) absence of cytotoxic effects; (iii) ability to support in vitro the adhesion and spreading of gingival fibroblasts; and (iv) antibiofilm properties. Although both silver and gallium exhibited in vitro strong antibacterial properties, in vivo gallium was significantly more effective than silver in reducing number and viability of biofilm bacteria colonies. Gallium-based treatments represent promising titanium antibiofilm coatings to develop new bone implantable devices for oral, maxillofacial, and orthopedic applications. © 2014 Wiley Periodicals, Inc.

  19. Novel solution-phase structures of gallium-containing pyrogallol[4]arene scaffolds**

    Science.gov (United States)

    Kumari, Harshita; Kline, Steven R.; Wycoff, Wei G.; Paul, Rick L.; Mossine, Andrew V.; Deakyne, Carol A.; Atwood, Jerry L.

    2012-01-01

    The variations in architecture of gallium-seamed (PgC4Ga) and gallium-zinc-seamed (PgC4GaZn) C-butylpyrogallol[4]arene nanoassemblies in solution (SANS/NMR) versus the solid state (XRD) have been investigated. Rearrangement from the solid-state spheroidal to the solution-phase toroidal shape differentiates the gallium-containing pyrogallol[4]arene nanoassemblies from all other PgCnM nanocapsules studied thus far. Different structural arrangements of the metals and arenes of PgC4Ga versus PgC4GaZn have been deduced from the different toroidal dimensions, C–H proton environments and guest encapsulation of the two toroids. PGAA of mixed-metal hexamers reveals a decrease in gallium-to-metal ratio as the second metal varies from cobalt to zinc. Overall, the combined study demonstrates the versatility of gallium in directing the self-assembly of pyrogallol[4]arenes into novel nanoarchitectures. PMID:22511521

  20. Quantifying garnet-melt trace element partitioning using lattice-strain theory: New crystal-chemical and thermodynamic constraints

    NARCIS (Netherlands)

    van Westrenen, W.; Draper, D.S.

    2007-01-01

    Many geochemical models of major igneous differentiation events on the Earth, the Moon, and Mars invoke the presence of garnet or its high-pressure majoritic equivalent as a residual phase, based on its ability to fractionate critical trace element pairs (Lu/Hf, U/Th, heavy REE/light REE). As a

  1. Constituting Antebellum African American Identity: Resistance, Violence, and Masculinity in Henry Highland Garnet's (1843) "Address to the Slaves"

    Science.gov (United States)

    Jasinski, James

    2007-01-01

    In August 1843 Presbyterian minister Henry Highland Garnet delivered his "Address to the Slaves of the United States of America" to the National Convention of Colored Citizens in Buffalo, NY. While often read (and almost as often dismissed) as either an unqualified call for a violent slave rebellion or, at the least, a celebration of…

  2. Timescales between mantle metasomatism and kimberlite ascent indicated by diffusion profiles in garnet crystals from peridotite xenoliths

    Science.gov (United States)

    Jollands, Michael C.; Hanger, Brendan J.; Yaxley, Gregory M.; Hermann, Jörg; Kilburn, Matthew R.

    2018-01-01

    Rare garnet crystals from a peridotite xenolith from the Wesselton kimberlite, South Africa, have distinct zones related to two separate episodes of mantle metasomatism. The garnet cores were firstly depleted through melt extraction, then equilibrated during metasomatism by a potentially diamond-forming carbonate-bearing or proto-kimberlitic fluid at 1100-1300 °C and 4.5-5.5 GPa. The garnet rim chemistry, in contrast, is consistent with later overgrowth in equilibrium with a kimberlite at around 1025 ± 25 °C and 4.2 ± 0.5 GPa. This suggests that the rock was physically moved upwards by up to tens of kilometres between the two metasomatic episodes. Preserved high Ca, Al and Cr contents in orthopyroxenes suggest this uplift was tectonic, rather than magmatic. Diffusion profiles were measured over the transitions between garnet cores and rims using electron microprobe (Mg, Ca, Fe for modelling, plus Cr, Mn, Ti, Na, Al) and nano Secondary Ion Mass Spectrometry (NanoSIMS; 89Y, along with 23Na, Ca, Cr, Fe, Mn and Ti) analyses. The short profile lengths (generally interaction of the mantle xenolith with the host kimberlite magma during a single-stage ascent to the crust (hours to days). The samples offer a rare opportunity to study metasomatic processes associated with failed eruption attempts in the cratonic lithosphere.

  3. Optical Properties of Strained Wurtzite Gallium Phosphide Nanowires

    KAUST Repository

    Greil, J.

    2016-06-08

    Wurtzite gallium phosphide (WZ GaP) has been predicted to exhibit a direct bandgap in the green spectral range. Optical transitions, however, are only weakly allowed by the symmetry of the bands. While efficient luminescence has been experimentally shown, the nature of the transitions is not yet clear. Here we apply tensile strain up to 6% and investigate the evolution of the photoluminescence (PL) spectrum of WZ GaP nanowires (NWs). The pressure and polarization dependence of the emission together with a theoretical analysis of strain effects is employed to establish the nature and symmetry of the transitions. We identify the emission lines to be related to localized states with significant admixture of Γ7c symmetry and not exclusively related to the Γ8c conduction band minimum (CBM). The results emphasize the importance of strongly bound state-related emission in the pseudodirect semiconductor WZ GaP and contribute significantly to the understanding of the optoelectronic properties of this novel material.

  4. Piezoelectric effect on the thermal conductivity of monolayer gallium nitride

    Science.gov (United States)

    Zhang, Jin

    2018-01-01

    Using molecular dynamics and density functional theory simulations, in this work, we find that the heat transport property of the monolayer gallium nitride (GaN) can be efficiently tailored by external electric field due to its unique piezoelectric characteristic. As the monolayer GaN possesses different piezoelectric properties in armchair and zigzag directions, different effects of the external electric field on thermal conductivity are observed when it is applied in the armchair and zigzag directions. Our further study reveals that due to the elastoelectric effect in the monolayer GaN, the external electric field changes the Young's modulus and therefore changes the phonon group velocity. Also, due to the inverse piezoelectric effect, the applied electric field induces in-plane stress in the monolayer GaN subject to a length constraint, which results in the change in the lattice anharmonicity and therefore affects the phonon mean free path. Furthermore, for relatively long GaN monolayers, the in-plane stress may trigger the buckling instability, which can significantly reduce the phonon mean free path.

  5. Mechanochemical activation and gallium and indiaarsenides surface catalycity

    Science.gov (United States)

    Kirovskaya, I. A.; Mironova, E. V.; Umansky, I. V.; Brueva, O. Yu; Murashova, A. O.; Yureva, A. V.

    2018-01-01

    The present work has been carried out in terms of determining the possibilities for a clearer identification of the active sites nature, intermediate surface compounds nature, functional groups during adsorption and catalysis, activation of the diamond-like semiconductors surface (in particular, the AIIIBV type) based on mechanochemical studies of the “reaction medium (H2O, iso-C3H7OH) - dispersible semiconductor (GaAs, InAs)” systems. As a result, according to the read kinetic curves of dispersion in water, both acidification and alkalinization of the medium have been established and explained; increased activity of the newly formed surface has been noted; intermediate surface compounds, functional groups appearing on the real surface and under H2O adsorption conditions, adsorption and catalytic decomposition of iso-C3H7OH have been found (with explanation of the origin). The unconcealed role of coordinatively unsaturated atoms as active sites of these processes has been shown; the relative catalytic activity of the semiconductors studied has been evaluated. Practical recommendations on the preferred use of gallium arsenide in semiconductor gas analysis and semiconductor catalysis have been given in literature searches, great care should be taken in constructing both.

  6. Investigation of a Gallium MPD Thruster with an Ablating Cathode

    Science.gov (United States)

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

    2010-01-01

    Arc impedance, exhaust velocity, and plasma probe measurements are presented. The thruster is driven by a 50 microsecond pulse from a 6.2 milliohm pulse forming network, and gallium is supplied to the discharge by evaporation of the cathode. The arc voltage is found to vary linearly with the discharge current with an arc impedance of 6.5 milliohms. Electrostatic probes yield an exhaust velocity that is invariant with the discharge current and has a peak value of 20 kilometers per second, which is in reasonable agreement with the value (16 plus or minus 1 kilometer per second) calculated from the mass bit and discharge current data. Triple probe measurements yield on axis electron temperatures in the range of 0.8-3.8 eV, electron densities in the range of 1.6 x 10(exp 21) to 2.1 x 10(exp 22) per cubic meter, and a divergence half angle of 16 degrees. Measurements within the interelectrode region yield a peak magnetic field of 0.8 T, and the observed radial trends are consistent with an azimuthally symmetric current distribution. A cathode power balance model is coupled with an ablative heat conduction model predicting mass bit values that are within 20% of the experimental values.

  7. The hyperfine properties of iron-gallium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M., E-mail: elzain@squ.edu.om; Gismelseed, A.; Al-Rawas, A.; Yousif, A.; Widatallah, H.; Al-Azri, Maya [Sultan Qaboos University, Department of Physics (Oman); Al-Barwani, M. [NYU Abu Dhabi (United Arab Emirates)

    2016-12-15

    The hyperfine properties at Fe site in iron-gallium alloy are calculated using the full-potential linear-augmented-plane-waves method. We have calculated the Fermi contact field (B{sub hf}) and isomer shift (δ) at the Fe site versus the number of neighbouring Ga atoms. We found that B{sub hf} decrease whereas δ increases with increasing number of neighbouring G atom. In addition we have calculated the hyperfine properties of FeGa system with DO{sub 3} structure, where various distributions of 4 the Ga atoms in the conventional unit cell are considered (including the regular DO{sub 3} structure). We found that the DO{sub 3} structure has the lowest energy as compared to the other configurations. The two distinct A and D sites of the ordered DO{sub 3} conventional unit cell have two distinct values for B{sub hf} and δ. On changing the atomic arrangement of the Ga atoms within the conventional unit cell, the configuration of the A site is maintained whereas that of the D site becomes imperfect. The contact magnetic hyperfine fields of the D-like sites in the imperfect structures are lower than that of the DO{sub 3}D site.

  8. Layer transfer of bulk gallium nitride by controlled spalling

    Science.gov (United States)

    Bedell, S. W.; Lauro, P.; Ott, J. A.; Fogel, K.; Sadana, D. K.

    2017-07-01

    Successful wafer-scale layer transfer from high-quality 2-in. diameter bulk gallium nitride substrates was demonstrated using the Controlled Spalling technique. The crystal quality of both the as-fractured bulk substrate and the spalled GaN film was assessed using transmission electron microscopy analysis, and the defect density was below the detection limit (mid 107 cm-2) for both samples. By using the experimentally determined critical conditions for tensile stress and thickness of the Ni stressor layer, an effective fracture toughness KIC of 1.7 MPa √{m } could be calculated for [0001] fracture using the Suo and Hutchinson mechanical model. The resulting in-plane contraction of the GaN film after spalling permitted a novel method for measuring film strain without knowledge of the elastic properties of the material. This was used to measure the Raman E2(high) peak shift coefficient of Δω(cm-1) = 1411ɛ which, when converted to a stress coefficient (2.95 cm-1/GPa), was in agreement with only one other literature value.

  9. Photoelectrochemical etching of gallium nitride surface by complexation dissolution mechanism

    Science.gov (United States)

    Zhang, Miao-Rong; Hou, Fei; Wang, Zu-Gang; Zhang, Shao-Hui; Pan, Ge-Bo

    2017-07-01

    Gallium nitride (GaN) surface was etched by 0.3 M ethylenediamine tetraacetic acid disodium (EDTA-2Na) via photoelectrochemical etching technique. SEM images reveal the etched GaN surface becomes rough and irregular. The pore density is up to 1.9 × 109 per square centimeter after simple acid post-treatment. The difference of XPS spectra of Ga 3d, N 1s and O 1s between the non-etched and freshly etched GaN surfaces can be attributed to the formation of Ga-EDTA complex at the etching interface between GaN and EDTA-2Na. The proposed complexation dissolution mechanism can be broadly applicable to almost all neutral etchants under the prerequisite of strong light and electric field. From the point of view of environment, safety and energy, EDTA-2Na has obvious advantages over conventionally corrosive etchants. Moreover, as the further and deeper study of such nearly neutral etchants, GaN etching technology has better application prospect in photoelectric micro-device fabrication.

  10. Schottky Barrier Transport for Multiphase Gallium Nitride Nanowire

    Science.gov (United States)

    Hartz, Steven; Xie, Kan; Liu, Zhun; Ayres, Virginia

    2013-03-01

    Our group has shown that gallium nitride nanowires grown by catalyst-free vapor deposition at 850oC have multiple internal crystalline regions that may be zinc blende or wurtzite phase. Stability is enabled by one or more totally coherent (0001)/(111) internal interfaces. Cross-section HRTEM has further demonstrated that, while the transverse nanowire profile appears triangular, it is actually made up of two or more surface orientations corresponding to the multi-phase internal regions. We present results of a transport investigation of these multiphase nanowires within a nanoFET circuit architecture, focusing on injection from the contacts into the nanowires. Experimental results demonstrated that a variety of surface state derived Schottky barriers could be present at the contact-nanowire interfaces. Transport across the Schottky barriers was modeled using a combined thermionic emission-tunnelling approach, leading to information about barrier height, carrier concentrations, and expected temperature behavior. The experimental and theoretical results indicate that with optimal design taking surface and internal structures into account, high current densities can be supported.

  11. Synthesis and luminescent study of Ce{sup 3+}-doped terbium-yttrium aluminum garnet

    Energy Technology Data Exchange (ETDEWEB)

    Dotsenko, V.P., E-mail: ssclab@ukr.net [A.V. Bogatsky Physico-Chemical Institute, National Academy of Sciences of Ukraine, Lustdorfskaya doroga 86, 65080 Odessa (Ukraine); Berezovskaya, I.V.; Zubar, E.V.; Efryushina, N.P. [A.V. Bogatsky Physico-Chemical Institute, National Academy of Sciences of Ukraine, Lustdorfskaya doroga 86, 65080 Odessa (Ukraine); Poletaev, N.I.; Doroshenko, Yu.A. [Institute of Combustion and Advanced Technologies, Mechnikov Odessa National University, Dvoryanskaya 2, 65082 Odessa (Ukraine); Stryganyuk, G.B. [Ivan Franko National University of Lviv, Kirilo i Mefodii 8, 79005 Lviv (Ukraine); HASYLAB at DESY, Notkestrasse 85, 22607 Hamburg (Germany); Voloshinovskii, A.S. [Ivan Franko National University of Lviv, Kirilo i Mefodii 8, 79005 Lviv (Ukraine)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer Ce{sup 3+}-doped garnets (TYAG) were prepared using nanostructured reagents. Black-Right-Pointing-Pointer The Ce{sup 3+} ions cause a very efficient yellow emission of the samples. Black-Right-Pointing-Pointer The reasons for the long wavelength position of this emission are discussed. Black-Right-Pointing-Pointer Contribution from Al atoms to the conduction band of TYAG is quite essential. - Abstract: Terbium-yttrium aluminum garnets (TYAG) doped with Ce{sup 3+} ions have been prepared by solid state reactions between nanostructured oxides of aluminum and rare earths. The luminescent properties of Ce{sup 3+} ions in (Tb{sub 0.8}Y{sub 0.2}){sub 3(1-x)}Ce{sub 3x}Al{sub 5}O{sub 12} (x = 0.03) have been studied upon excitation in the 2-20 eV region. The substitution of Tb{sup 3+} for Y{sup 3+} in the garnet structure results in broadening the emission band and shifting its maximum towards the longer wavelengths. It was found that in addition to the 4f{sup n} {yields} 4f{sup n-1}5d excitation bands of Ce{sup 3+} and Tb{sup 3+} ions, the excitation spectra for the Ce{sup 3+} emission contain broad bands at 6.73 and {approx}9.5 eV. These bands are attributed to the Ce{sup 3+}-bound exciton formation and O 2p {yields} Al 3s, 3p transitions, respectively. In contrast to the predictions based on the results of electronic structure calculations on Y{sub 3}Al{sub 5}O{sub 12} and Tb{sub 4}Al{sub 2}O{sub 9}, the threshold of interband transitions in TYAG is at high energies ( Greater-Than-Or-Slanted-Equal-To 7.3 eV), and contributions from Al{sub tetr} and Al{sub oct} atoms to the conduction-band density of states are evaluated as quite essential.

  12. High-perfomance Ce-doped multicomponent garnet single crystalline film scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Zorenko, Yu.; Gorbenko, V.; Zorenko, T. [Institute of Physics, Kazimierz Wielki, University in Bydgoszcz, Powstancow, Wielkopolskich str., 2, 85090, Bydgoszcz (Poland); Department of Electronics of Ivan Franko, National University of Lviv, Gen. Tarnavskiy str. 17, 79017, Lviv (Ukraine); Sidletskiy, O. [Institute for Single Crystals, National Academy of Sciences of Ukraine, Lenina str., 60, 61001, Kharkiv (Ukraine); Fedorov, A. [SSI Institute for Single Crystals, National Academy of Sciences of Ukraine, Lenina str., 60, 61178, Kharkiv (Ukraine); Bilski, P.; Twardak, A. [Institute of Nuclear Physic, Polish Academy of Sciences, Radzikowskiego str., 176, 31-342, Krakow (Poland)

    2015-08-15

    We report for the first time the optimized content and excellent scintillation properties of single crystalline film (SCF) scintillators of multicomponent Gd{sub 3-x}Lu{sub x} Al{sub 5-y}Ga{sub y} O{sub 12}:Ce garnet compounds grown by liquid phase epitaxy (LPE) method. The Gd{sub 1.5}Lu{sub 1.5}Al{sub 2.75}Ga{sub 2.25}O{sub 12}:Ce and Gd{sub 3}Al{sub 2.75-2}Ga{sub 2.25-3}O{sub 12}:Ce SCF show the light yield (LY) comparable with that of high-quality bulk crystal analogues of these garnets but faster scintillation decay and very low thermoluminescence in the above room temperature range. To our knowledge, these SCF possess the highest LY values ever obtained in LPE grown garnet SCF scintillators exceeding by at least 1.5-1.6 times the values previously reported for SCF scintillators. Left figure: image of Gd{sub 1.5}Lu{sub 1.5}Al{sub 2.75}Ga{sub 2.25}O{sub 12}:Ce (PbO) (inset, left) and Gd{sub 3}Al{sub 2.35}Ga{sub 2.65}O{sub 12}:Ce (BaO) (inset, right) SCF scintillators, grown by LPE method onto Gd{sub 3}Al{sub 2.5}Ga{sub 2.5}O{sub 12} (GAGG) substrate; in the middle, green-yellow light emitting by Gd{sub 1.5}Lu{sub 1.5}Al{sub 2.75}Ga{sub 2.25}O{sub 12}:Ce (BaO) SCF under 350 nm laser illumination. Right figure: XRD pattern of (1200) planes of the Gd{sub 1.5}Lu{sub 1.5}Al{sub 2.75}Ga{sub 2.25}O{sub 12}:Ce (PbO) (black) and Gd{sub 3}Al{sub 2.75}Ga{sub 2.25}O{sub 12}:Ce (BaO) (red) SCFs, grown onto GAGG substrates. The film/substrate lattice misfit is -0.73% and -0.3%, respectively. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Lacrimal gland uptake of (67)Ga-gallium citrate correlates with biopsy results in patients with suspected sarcoidosis.

    Science.gov (United States)

    Tannen, Bradford L; Kolomeyer, Anton M; Turbin, Roger E; Frohman, Larry; Langer, Paul D; Oh, Cheongeun; Ghesani, Nasrin V; Zuckier, Lionel S; Chu, David S

    2014-02-01

    To investigate whether lacrimal gland uptake on (67)Ga-gallium citrate scintigraphy correlates with histopathologic evidence of sarcoidosis. A retrospective, pilot study of 31 patients with suspected sarcoidosis who underwent gallium scintigraphy and lacrimal gland biopsy. Lacrimal gland gallium uptake was assessed by subjective visual scoring (SVS) and lacrimal uptake ratio (LUR). Eleven (36%) patients had lacrimal gland biopsies containing noncaseating granulomas. A statistically significant correlation was found between lacrimal gland gallium uptake and biopsy positivity using SVS (p = 0.03) or LUR (p = 0.01). Using SVS, biopsy positivity rate increased from 0 to 50% in patients with mild to intense uptake. Using LUR, biopsy positivity rate increased linearly as the ratio increased from 13% (LUR  8). Lacrimal biopsy positivity rate significantly correlated with gallium uptake on scintigraphy. Both SVS and LUR methods appear to correlate with histologic results and may potentially aid in patient selection for biopsy.

  14. Gallium nitrate induces fibrinogen flocculation: an explanation for its hemostatic effect?

    Science.gov (United States)

    Bauters, A; Holt, D J; Zerbib, P; Rogosnitzky, M

    2013-12-01

    A novel hemostatic effect of gallium nitrate has recently been discovered. Our aim was to perform a preliminary investigation into its mode of action. Thromboelastography® showed no effect on coagulation but pointed instead to changes in fibrinogen concentration. We measured functional fibrinogen in whole blood after addition of gallium nitrate and nitric acid. We found that gallium nitrate induces fibrinogen precipitation in whole blood to a significantly higher degree than solutions of nitric acid alone. This precipitate is not primarily pH driven, and appears to occur via flocculation. This behavior is in line with the generally observed ability of metals to induce fibrinogen precipitation. Further investigation is required into this novel phenomenon.

  15. Magnetoelectric effect in layered structures of amorphous ferromagnetic alloy and gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Bichurin, M.I., E-mail: mirza.bichurin@novsu.ru; Petrov, V.M.; Leontiev, V.S.; Ivanov, S.N.; Sokolov, O.V.

    2017-02-15

    A paper devotes to theoretical and experimental studying the magnetoelectric interaction in layered structures of amorphous ferromagnetic alloy and single- crystal gallium arsenide. The authors investigated the magnetoelectric effect in the (100) plane of gallium arsenide in the electromechanical resonance range of 200–240 kHz and obtained maximal ME voltage coefficient of 120 V/A at bias field equaled 3.6 kA/m for the direction parallel to the [011] axis. Also the magnetoelectric effect in the (110) and (111) planes is discussed. The results can be used for design of new electronic devices based on the magnetostrictive-semiconductor materials. - Highlights: • Theoretical modeling of ME interaction was conducted. • Experimental dependencies in the resonance range were done. • Maximal ME effect of gallium arsenide was observed.

  16. Gallium-Based Room-Temperature Liquid Metals: Actuation and Manipulation of Droplets and Flows

    Directory of Open Access Journals (Sweden)

    Leily Majidi

    2017-08-01

    Full Text Available Gallium-based room-temperature liquid metals possess extremely valuable properties, such as low toxicity, low vapor pressure, and high thermal and electrical conductivity enabling them to become suitable substitutes for mercury and beyond in wide range of applications. When exposed to air, a native oxide layer forms on the surface of gallium-based liquid metals which mechanically stabilizes the liquid. By removing or reconstructing the oxide skin, shape and state of liquid metal droplets and flows can be manipulated/actuated desirably. This can occur manually or in the presence/absence of a magnetic/electric field. These methods lead to numerous useful applications such as soft electronics, reconfigurable devices, and soft robots. In this mini-review, we summarize the most recent progresses achieved on liquid metal droplet generation and actuation of gallium-based liquid metals with/without an external force.

  17. Renal gallium accumulation in rats with antibiotic-induced nephritis: clinical implications. Concise communication

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, A.; Nelson, H.; Vasquez, M.; Hollenbeck, J.

    1980-07-01

    To determine the effect of antibiotic-induced nephrotoxicity on the renal accumulation of gallium, groups of ten Sprague-Dawley rats were given intraperitoneal injections of gentamycin, amphotericin, or neomycin for a period of 16 to 21 days. In all cases, mild to moderate nephrotoxicity was documented by one or more of the following parameters: serum creatinine, renal weight, urine volume (renal concentrating ability), light microscopy, and electron microscopy. In none of these cases was the renal accumulation of gallium increased over control values. Consequently, diffuse renal accumulation of gallium in patients with subclinical or mild nephrotoxicity is unlikely to be related to short-term treatment with aminoglycosides or amphotericin. In such cases, the physician should seek some other clinical explanation, such as infection.

  18. Surface-enhanced gallium arsenide photonic resonator with a quality factor of six million

    CERN Document Server

    Guha, Biswarup; Cadiz, Fabian; Morgenroth, Laurence; Ulin, Vladimir; Berkovitz, Vladimir; Lemaître, Aristide; Gomez, Carmen; Amo, Alberto; Combrié, Sylvian; Gérard, Bruno; Leo, Giuseppe; Favero, Ivan

    2016-01-01

    Gallium Arsenide and related compound semiconductors lie at the heart of optoelectronics and integrated laser technologies. Shaped at the micro and nano-scale, they allow strong interaction with quantum dots and quantum wells, and promise to result in stunning devices. However gallium arsenide optical structures presently exhibit lower performances than their silicon-based counterparts, notably in nanophotonics where the surface plays a chief role. Here we report on advanced surface control of miniature gallium arsenide optical resonators, using two distinct techniques that produce permanent results. One leads to extend the lifetime of free-carriers and enhance luminescence, while the other strongly reduces surface absorption originating from mid-gap states and enables ultra-low optical dissipation devices. With such surface control, the quality factor of wavelength-sized optical disk resonators is observed to rise up to six million at telecom wavelength, greatly surpassing previous realizations and opening n...

  19. Discovery of a New Garnet Mineral, Hutcheonite, in the Allende Meteorite

    Science.gov (United States)

    Martel, L. M. V.

    2013-09-01

    A new titanium-rich garnet mineral has been found in a FUN CAI (a rare type of calcium-aluminum-rich inclusion, CAI) from the Allende carbonaceous chondrite, as reported by the discovery team of Chi Ma (CalTech) and Alexander Krot (University of Hawaii). The mineral, IMA 2013-029, was officially approved in June 2013 by the Commission on New Minerals, Nomenclature, and Classification of the International Mineralogical Association as hutcheonite. The mineral's name honors Ian D. Hutcheon, a researcher at Lawrence Livermore National Laboratory, who is a leading authority in the chronology of the early Solar System, especially known for his significant contributions to the development of instrumentation and techniques for isotopic and elemental microanalysis. Researchers Ma and Krot say hutcheonite in Allende is likely an alteration phase formed by iron-alkali-halogen metasomatism of the primary phases in the FUN CAI.

  20. Tattoo removal by Q-switched yttrium aluminium garnet laser: client satisfaction

    DEFF Research Database (Denmark)

    Hutton Carlsen, K; Esmann, J; Serup, J

    2017-01-01

    BACKGROUND: Tattoo removal by Q-switched yttrium aluminium garnet (YAG) lasers is golden standard; however, clients' satisfaction with treatment is little known. OBJECTIVE: To determine clients' satisfaction with tattoo removal. METHODS: One hundred and fifty-four tattoo removal clients who had...... attended the private clinic 'Centre for Laser Surgery', Hellerup, Denmark, from 2001 to 2013 completed a questionnaire concerning outcome expectations, level of pain experiences and satisfaction with tattoo removal. The laser surgeon and his team were blinded from data handling. The study design included...... relative to colour of tattoo on a scale from 0 (no effect) to 10 (complete removal) scored a mean of blue 9.5, black 9.4, yellow 8.9, red 8.8 and green 6.5. Clients were dissatisfied with green pigment remnants, which could mimic bruising. One hundred and twenty-nine clients (84%) experienced moderate...

  1. Extremely flat transmission band of forward volume spin wave using gold and yttrium iron garnet

    Science.gov (United States)

    Shimada, Kei; Goto, Taichi; Kanazawa, Naoki; Takagi, Hiroyuki; Nakamura, Yuichi; Uchida, Hironaga; Inoue, Mitsuteru

    2017-07-01

    An extremely flat transmission band for a forward volume spin wave (SW) propagating in an SW waveguide composed of yttrium iron garnet film and SW absorbers was obtained, using the finite integration technique. Three-dimensional analysis of the calculated results showed that the transmission ripples of the SWs propagating in the waveguide were caused by SW interference, especially that due to two standing waves originating from the waveguide edge-edge and the waveguide-antenna edge. To suppress these waves, SW absorbers composed of gold film were introduced and the resultant positions and shapes were investigated precisely. Hence, an extremely flat transmission band was obtained. The results of this study have potential application in the development of one- and two-dimensional magnonic crystals for integrated SW devices.

  2. Lateral transport properties of thermally excited magnons in yttrium iron garnet films

    Science.gov (United States)

    Zhou, X. J.; Shi, G. Y.; Han, J. H.; Yang, Q. H.; Rao, Y. H.; Zhang, H. W.; Lang, L. L.; Zhou, S. M.; Pan, F.; Song, C.

    2017-02-01

    Spin information carried by magnons is attractive for computing technology, and the development of magnon-based computing circuits is of great interest. However, magnon transport in insulators has been challenging, different from the clear physical picture for spin transport in conductors. Here, we investigate the lateral transport properties of thermally excited magnons in yttrium iron garnet (YIG), a model magnetic insulator. Polarity reversals of detected spins in non-local geometry devices have been experimentally observed and are strongly dependent on temperature, YIG film thickness, and injector-detector separation distance. A competing two-channel transport model for thermally excited magnons is proposed, which is qualitatively consistent with the spin signal behavior. In addition to the fundamental significance for thermal magnon transport, our work furthers the development of magnonics by creating an easily accessible magnon source with controllable transport.

  3. The longevity of Neotethyan metamorphic soles from Lu-Hf garnet chronology

    Science.gov (United States)

    Peters, Kalijn; Smit, Matthijs; van Hinsbergen, Douwe; van Roermund, Herman; Brouwer, Fraukje

    2017-04-01

    Supra-subduction zone (SSZ) ophiolites typically have a few-hundred-meters thick sequence of metamorphic rocks below their mantle section: a so-called metamorphic sole. Metamorphic soles are derived from oceanic crustal rocks, and they typically show an inverted metamorphic field gradient, ranging from greenschist-facies at the bottom to upper-amphibolite or granulite facies near the contact with the overlying peridotite. The soles are interpreted to represent the top of a nascent subducting slab that accreted to the base of the hot overriding plate. Studying the formation and exhumation of metamorphic soles is key to characterizing the inception of subduction in oceanic settings. Chronology is an important research tool in this regard and is typically done using 40Ar/39Ar thermochronology on amphibolite-hosted hornblende. The 40Ar/39Ar dates of metamorphic soles invariably overlap with the ages of the crust of SSZ ophiolites, suggesting that spreading and sole cooling are causally linked. The time between the inception of subduction and sole cooling is generally assumed to be short, but unquantified. In this study, we shed light on this aspect of ophiolite evolution by petrological analysis and multi-mineral chronology on the Late Cretaceous Pιnarbaşι metamorphic sole, central Turkey, and the Jurassic metamorphic soles of the Pindos and Vourinos ophiolites, northern Greece. These Tethyan SSZ ophiolites show, with the exception of Vourinos, well-exposed sole sections, of which the different metamorphic levels were subjected to our integrated analytical approach. In this presentation we show the results from Lu-Hf dating of garnet from the highest grade garnet-amphibolites of the Pιnarbaşι and Vourinos ophiolites and the lower grade garnet-micaschists of the sole at Pindos. The Lu-Hf system in garnet enables reliable age constraints on the growth of this important prograde index mineral, allowing better approximation of the timing of subduction initiation than

  4. Nucleation of domain walls in iron garnet single crystals grown from liquid phase epitaxy

    Science.gov (United States)

    Shirai, Kazushi; Ishikura, Kenji; Takeda, Norio

    1997-09-01

    When bismuth-substituted iron garnet (RBi)IG single crystals grown from liquid-phase-epitaxy (LPE) are magnetized, the magnetic domain structure gradually evolves. However the domain-wall nucleation that occurs during the demagnetization is not yet understood clearly. This phenomenon is important, because the working of some optical devices that utilize (RBi)IG single crystals depends directly on the formation of domains of opposite direction. In this paper, the authors present a theoretical description of domain-wall nucleation in LPE-grown (RBi)IG single crystals. It was found that the nucleation field is determined by the strength of the microscopic domain-wall which is fixed on the surface of the crystal. Furthermore, the nucleation field is modified by the addition of a magnetic field.

  5. The absorption property of single crystal LuBiIG garnet film in terahertz band

    Science.gov (United States)

    Yang, Qing-Hui; Zhang, Huai-Wu; Wen, Qi-Ye; Liu, Ying-Li

    2012-04-01

    In this paper, a hypothesis has been brought forward that the materials with low propagation loss in both optical and microwave band may exhibit good performance in terahertz (THz) band because THz wave band interspaces those two wave bands. Several kinds of single crystal garnet films were investigated and we found that the Lu2.1Bi0.9Fe5O12 film which grows by liquid phase epitaxy (LPE) from PbO-free flux has the best absorption properties in both microwave and optical band. In THz range, our hypothesis is well confirmed by a THz-TDS measurement which shows that the absorption coefficient of LuBiIG film is 0.05-0.3 cm-1, and the minimum value appears at 2.24 THz.

  6. Zirconology of garnet-glaucophane schists of the Maksyutov complex (Southern Urals)

    Science.gov (United States)

    Krasnobaev, A. A.; Valizer, P. M.; Anfilogov, V. N.; Busharina, S. V.

    2015-04-01

    The studies of zircons from garnet-glaucophane schists of the Maksyutov complex (Novotashlinskii area) have shown that their substrate was constituted of magmatic gabbroids of Neoproterozoic age (670 Ma). The long-term evolution of zircons encompassed the interval from the Neoproterozoic until the Carboniferous (673.1 ± 5.4, 592.6 ± 9.4, 517.0 ± 7.4, 444.9 ± 4.7, and 323.0 ± 8.8 Ma) and proceeded within a common geochemical area including the stages of inversed development with changes in the zircon compositions, involving the processes of crushing and dissolution. Unit II of the complex contains metamagmatic rocks, which points to the participation of a wider variety of rocks of different compositions and ages in the Maksyutov complex.

  7. Ohmic contact formation process on low n-type gallium arsenide (GaAs) using indium gallium zinc oxide (IGZO)

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Seong-Uk [Samsung-SKKU Graphene Center and School of Electronics and Electrical Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Product and Test Engineering Team, System LSI Division, Samsung Electronics Co., Ltd, Yongin 446-711 (Korea, Republic of); Jung, Woo-Shik [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Lee, In-Yeal; Jung, Hyun-Wook; Kim, Gil-Ho [Samsung-SKKU Graphene Center and School of Electronics and Electrical Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Park, Jin-Hong, E-mail: jhpark9@skku.edu [Samsung-SKKU Graphene Center and School of Electronics and Electrical Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2014-02-01

    Highlights: • We propose a method to fabricate non-gold Ohmic contact on low n-type GaAs with IGZO. • 0.15 A/cm{sup 2} on-current and 1.5 on/off-current ratio are achieved in the junction. • InAs and InGaAs formed by this process decrease an electron barrier height. • Traps generated by diffused O atoms also induce a trap-assisted tunneling phenomenon. - Abstract: Here, an excellent non-gold Ohmic contact on low n-type GaAs is demonstrated by using indium gallium zinc oxide and investigating through time of flight-secondary ion mass spectrometry, X-ray photoelectron spectroscopy, transmission electron microscopy, J–V measurement, and H [enthalpy], S [entropy], Cp [heat capacity] chemistry simulation. In is diffused through GaAs during annealing and reacts with As, forming InAs and InGaAs phases with lower energy bandgap. As a result, it decreases the electron barrier height, eventually increasing the reverse current. In addition, traps generated by diffused O atoms induce a trap-assisted tunneling phenomenon, increasing generation current and subsequently the reverse current. Therefore, an excellent Ohmic contact with 0.15 A/cm{sup 2} on-current density and 1.5 on/off-current ratio is achieved on n-type GaAs.

  8. The comparison between gallium arsenide and indium gallium arsenide as materials for solar cell performance using Silvaco application

    Energy Technology Data Exchange (ETDEWEB)

    Zahari, Suhaila Mohd; Norizan, Mohd Natashah; Mohamad, Ili Salwani; Osman, Rozana Aina Maulat; Taking, Sanna [School of Microelectronic Engineering, Universiti Malaysia Perlis, Kampus Pauh Putra, 02600 Arau, Perlis (Malaysia)

    2015-05-15

    The work presented in this paper is about the development of single and multilayer solar cells using GaAs and InGaAs in AM1.5 condition. The study includes the modeling structure and simulation of the device using Silvaco applications. The performance in term of efficiency of Indium Gallium Arsenide (InGaAs) and GaAs material was studied by modification of the doping concentration and thickness of material in solar cells. The efficiency of the GaAs solar cell was higher than InGaAs solar cell for single layer solar cell. Single layer GaAs achieved an efficiency about 25% compared to InGaAs which is only 2.65% of efficiency. For multilayer which includes both GaAs and InGaAs, the output power, P{sub max} was 8.91nW/cm² with the efficiency only 8.51%. GaAs is one of the best materials to be used in solar cell as a based compared to InGaAs.

  9. The comparison between gallium arsenide and indium gallium arsenide as materials for solar cell performance using Silvaco application

    Science.gov (United States)

    Zahari, Suhaila Mohd; Norizan, Mohd Natashah; Mohamad, Ili Salwani; Osman, Rozana Aina Maulat; Taking, Sanna

    2015-05-01

    The work presented in this paper is about the development of single and multilayer solar cells using GaAs and InGaAs in AM1.5 condition. The study includes the modeling structure and simulation of the device using Silvaco applications. The performance in term of efficiency of Indium Gallium Arsenide (InGaAs) and GaAs material was studied by modification of the doping concentration and thickness of material in solar cells. The efficiency of the GaAs solar cell was higher than InGaAs solar cell for single layer solar cell. Single layer GaAs achieved an efficiency about 25% compared to InGaAs which is only 2.65% of efficiency. For multilayer which includes both GaAs and InGaAs, the output power, Pmax was 8.91nW/cm² with the efficiency only 8.51%. GaAs is one of the best materials to be used in solar cell as a based compared to InGaAs.

  10. Formation of Flexible and Transparent Indium Gallium Zinc Oxide/Ag/Indium Gallium Zinc Oxide Multilayer Film

    Science.gov (United States)

    Kim, Jun Ho; Kim, Da-Som; Kim, Sun-Kyung; Yoo, Young-Zo; Lee, Jeong Hwan; Kim, Sang-Woo; Seong, Tae-Yeon

    2016-08-01

    In this study, the electrical, optical, and bending characteristics of amorphous indium gallium zinc oxide (IGZO)/Ag/IGZO (39 nm/19 nm/39 nm) multilayer films deposited on polyethylene terephthalate (PET) substrate at room temperature were investigated and compared with those of Sn-doped indium oxide (ITO) (100 nm thick) films. At 500 nm the ITO film transmitted 91.3% and the IGZO/Ag/IGZO multilayer film transmitted 88.8%. The calculated transmittance spectrum of the multilayer film was similar to the experimental result. The ITO film and IGZO/Ag/IGZO multilayer film, respectively, showed carrier concentrations of 1.79 × 1020 and 7.68 × 1021 cm-3 and mobilities of 27.18 cm2/V s and 18.17 cm2/V s. The ITO film had a sheet resistance of 134.9 Ω/sq and the IGZO/Ag/IGZO multilayer film one of 5.09 Ω/sq. Haacke's figure of merit (FOM) was calculated to be 1.94 × 10-3 for the ITO film and 45.02 × 10-3 Ω-1 for the IGZO/Ag/IGZO multilayer film. The resistance change of 100 nm-thick ITO film was unstable even after five cycles, while that of the IGZO/Ag/IGZO film was constant up to 1000 cycles.

  11. A Rechargeable Li-Air Fuel Cell Battery Based on Garnet Solid Electrolytes

    Science.gov (United States)

    Sun, Jiyang; Zhao, Ning; Li, Yiqiu; Guo, Xiangxin; Feng, Xuefei; Liu, Xiaosong; Liu, Zhi; Cui, Guanglei; Zheng, Hao; Gu, Lin; Li, Hong

    2017-01-01

    Non-aqueous Li-air batteries have been intensively studied in the past few years for their theoretically super-high energy density. However, they cannot operate properly in real air because they contain highly unstable and volatile electrolytes. Here, we report the fabrication of solid-state Li-air batteries using garnet (i.e., Li6.4La3Zr1.4Ta0.6O12, LLZTO) ceramic disks with high density and ionic conductivity as the electrolytes and composite cathodes consisting of garnet powder, Li salts (LiTFSI) and active carbon. These batteries run in real air based on the formation and decomposition at least partially of Li2CO3. Batteries with LiTFSI mixed with polyimide (PI:LiTFSI) as a binder show rechargeability at 200 °C with a specific capacity of 2184 mAh g-1carbon at 20 μA cm-2. Replacement of PI:LiTFSI with LiTFSI dissolved in polypropylene carbonate (PPC:LiTFSI) reduces interfacial resistance, and the resulting batteries show a greatly increased discharge capacity of approximately 20300 mAh g-1carbon and cycle 50 times while maintaining a cutoff capacity of 1000 mAh g-1carbon at 20 μA cm-2 and 80 °C. These results demonstrate that the use of LLZTO ceramic electrolytes enables operation of the Li-air battery in real air at medium temperatures, leading to a novel type of Li-air fuel cell battery for energy storage.

  12. Effect of novel antibacterial gallium-carboxymethyl cellulose on Pseudomonas aeruginosa.

    Science.gov (United States)

    Valappil, Sabeel P; Yiu, Humphrey H P; Bouffier, Laurent; Hope, Christopher K; Evans, Gary; Claridge, John B; Higham, Susan M; Rosseinsky, Matthew J

    2013-02-07

    Gallium has emerged as a new therapeutic agent due partly to the scarcity in development of new antibiotics. In this study, a novel antibacterial gallium exchanged carboxymethyl cellulose (Ga-CMC) has been developed and tested for the susceptibility on a common bacteria, Pseudomonas aeruginosa. The results show that an increase in average molecular weight (MW) from 90 k, 250 k to 700 k of Ga-CMC caused a decrease in antimicrobial activity against planktonic P. aeruginosa. Gallium loading of the Ga-CMC (250 k) samples was altered by varying the amount of functionality (0.7, 0.9 and 1.2 acid groups per mole of carbohydrate) which affected also its antimicrobial activity against planktonic P. aeruginosa. Further, the ability to prevent the growth of biofilms of P. aeruginosa was tested on MW = 250 k samples with 0.9 acid groups per mole of carbohydrate as this sample showed the most promising activity against planktonic P. aeruginosa. Gallium was found to reduce biofilm growth of P. aeruginosa with a maximum effect (0.85 log(10) CFU reduction compared to sodium-carboxymethyl cellulose, Na-CMC) after 24 h. Results of the solubility and ion exchange studies show that this compound is suitable for the controlled release of Ga(3+) upon their breakdown in the presence of bacteria. SEM EDX analysis confirmed that Ga(3+) ions are evenly exchanged on the cellulose surface and systematic controls were carried out to ensure that antibacterial activity is solely due to the presence of gallium as samples intrinsic acidity or nature of counterion did not affect the activity. The results presented here highlight that Ga-CMC may be useful in controlled drug delivery applications, to deliver gallium ions in order to prevent infections due to P. aeruginosa biofilms.

  13. Semi-quantitative evaluation of gallium-67 scintigraphy in lupus nephritis

    Energy Technology Data Exchange (ETDEWEB)

    Lin Wanyu [Dept. of Nuclear Medicine, Taichung Veterans General Hospital, Taichung (Taiwan); Dept. of Radiological Technology, Chung-Tai College of Medical Technology, Taichung (Taiwan); Hsieh Jihfang [Section of Nuclear Medicine, Chi-Mei Foundation Hospital, Yunk Kang City, Tainan (Taiwan); Tsai Shihchuan [Dept. of Nuclear Medicine, Show Chwan Memorial Hospital, Changhua (Taiwan); Lan Joungliang [Dept. of Internal Medicine, Taichung Veterans General Hospital, Taichung (Taiwan); Cheng Kaiyuan [Dept. of Radiological Technology, Chung-Tai College of Medical Technology, Taichung (Taiwan); Wang Shyhjen [Dept. of Nuclear Medicine, Taichung Veterans General Hospital, Taichung (Taiwan)

    2000-11-01

    Within nuclear medicine there is a trend towards quantitative analysis. Gallium renal scan has been reported to be useful in monitoring the disease activity of lupus nephritis. However, only visual interpretation using a four-grade scale has been performed in previous studies, and this method is not sensitive enough for follow-up. In this study, we developed a semi-quantitative method for gallium renal scintigraphy to find a potential parameter for the evaluation of lupus nephritis. Forty-eight patients with lupus nephritis underwent renal biopsy to determine World Health Organization classification, activity index (AI) and chronicity index (CI). A delayed 48-h gallium scan was also performed and interpreted by visual and semi-quantitative methods. For semi-quantitative analysis of the gallium uptake in both kidneys, regions of interest (ROIs) were drawn over both kidneys, the right forearm and the adjacent spine. The uptake ratios between these ROIs were calculated and expressed as the ''kidney/spine ratio (K/S ratio)'' or the ''kidney/arm ratio (K/A ratio)''. Spearman's rank correlation test and Mann-Whitney U test were used for statistical analysis. Our data showed a good correlation between the semi-quantitative gallium scan and the results of visual interpretation. K/S ratios showed a better correlation with AI than did K/A ratios. Furthermore, the left K/S ratio displayed a better correlation with AI than did the right K/S ratio. In contrast, CI did not correlate well with the results of semi-quantitative gallium scan. In conclusion, semi-quantitative gallium renal scan is easy to perform and shows a good correlation with the results of visual interpretation and renal biopsy. The left K/S ratio from semi-quantitative renal gallium scintigraphy displays the best correlation with AI and is a useful parameter in evaluating the disease activity in lupus nephritis. (orig.)

  14. Gallium-containing phospho-silicate glasses: Synthesis and in vitro bioactivity

    Energy Technology Data Exchange (ETDEWEB)

    Franchini, Mirco; Lusvardi, Gigliola; Malavasi, Gianluca, E-mail: gmalavasi@unimo.it; Menabue, Ledi

    2012-08-01

    A series of Ga-containing phospho-silicate glasses based on Bioglass 45S5, having molar formula 46.2SiO{sub 2}{center_dot}24.3Na{sub 2}O{center_dot}26.9CaO{center_dot}2.6P{sub 2}O{sub 5}{center_dot}xGa{sub 2}O{sub 3} (x = 1.0, 1.6, 3.5), were prepared by fusion method. The reference Bioglass 45S5 without gallium was also prepared. The synthesized glasses were immersed in simulated body fluid (SBF) for 30 days in order to observe ion release and hydroxyapatite (HA) formation. All Ga-containing glasses maintain the ability of HA formation as indicated by main X-ray diffractometric peaks and/or electronic scanning microscopy results. HA layer was formed after 1 day of SBF soaking in 45S5 glass containing up to 1.6% Ga{sub 2}O{sub 3} content. Moreover, gallium released by the glasses was found to be partially precipitated on the glass surface as gallium phosphate. Further increase in gallium content reduced the ion release in SBF. The maximum of Ga{sup 3+} concentration measured in solution is {approx} 6 ppm determined for 3.5% Ga{sub 2}O{sub 3} content. This amount is about half of the toxic level (14 ppm) of gallium and the glasses release gallium till 30 days of immersion in SBF. Considering the above results, the studied materials can be proposed as bioactive glasses with additional antimicrobial effect of gallium having no toxic outcome. - Highlights: Black-Right-Pointing-Pointer A new class of potential bioactive glasses gallium content. Black-Right-Pointing-Pointer Controlled ions release from the glass surface. Black-Right-Pointing-Pointer Effect of Ga{sub 2}O{sub 3} content on bioactivity (hydroxyapatite formation). Black-Right-Pointing-Pointer Formation of calcite when the phosphate concentration is low in SBF.

  15. Gallium-SPECT in the detection of prosthetic valve endocarditis and aortic ring abscess

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, K.; Barnes, D.; Martin, R.H.; Rae, J.R. (Department of Diagnostic Radiology, Victoria General Hospital Halifax, Nova Scotia (Canada))

    1991-09-01

    A 52-yr-old man who had a bioprosthetic aortic valve developed Staphylococcus aureus bacteremia. Despite antibiotic therapy he had persistent pyrexia and developed new conduction system disturbances. Echocardiography did not demonstrate vegetations on the valve or an abscess, but gallium scintigraphy using SPECT clearly identified a focus of intense activity in the region of the aortic valve. The presence of valvular vegetations and a septal abscess was confirmed at autopsy. Gallium scintigraphy, using SPECT, provided a useful noninvasive method for the demonstration of endocarditis and the associated valve ring abscess.

  16. Experience in staging testis tumors with bleomycin cobalt 57 and present role of gallium 67 scan

    Energy Technology Data Exchange (ETDEWEB)

    Mukerjee, M.G.; Mittemeyer, B.T.

    1976-10-01

    A technique was developed using bleomycin and cobalt 57 to study nodal metastases in testis tumors. Comparative studies were made on 15 cases with gallium 67, lymphangiography, supraclavicular node biopsy, liver and spleen scans, chest x-ray, excretory urogram, bone survey and pathological study of surgical specimens when possible. The results with the bleomycin-cobalt 57 complex and gallium 67 were discouraging. The bleomycin-cobalt 57 study was discontinued. Pathological staging is still the most accurate of all modalities available for staging testicular malignancies.

  17. Development of a Free Carrier Absorption Measurement Instrument for Indium Phosphide and Gallium Arsenide.

    Science.gov (United States)

    1986-10-27

    AD-A174 ř DEVELOPMENT OF R FREE CARRIER ABSORPTION MEASUREMENT 1/2 INSTRUMENT FOR INDTU (U) EAGLE-PICHER RESEARCH LAB MIAMI OK SPECIALTY MATERIALS...SOBI S D Final Report Development of a Free Carrier Absorption Measurement Instrument For Indium Phosphide and Gallium Arsenide EAGLE PICHER R ES EA R CH...i P r OTic S D L C T DEC 0 3 ang Final Report Development of a Free Carrier Absorption Measurement Instrument For Indium Phosphide and Gallium

  18. Results of the Gallium-Clad Phase 3 and Phase 4 tasks (canceled prior to completion)

    Energy Technology Data Exchange (ETDEWEB)

    Morris, R.N.

    1998-08-01

    This report summarizes the results of the Gallium-Clad interactions Phase 3 and 4 tasks. Both tasks were to involve examining the out-of-pile stability of residual gallium in short fuel rods with an imposed thermal gradient. The thermal environment was to be created by an electrical heater in the center of the fuel rod and coolant flow on the rod outer cladding. Both tasks were canceled due to difficulties with fuel pellet fabrication, delays in the preparation of the test apparatus, and changes in the Fissile Materials Disposition program budget.

  19. Thermal Cycling and High Temperature Reverse Bias Testing of Control and Irradiated Gallium Nitride Power Transistors

    Science.gov (United States)

    Patterson, Richard L.; Boomer, Kristen T.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2014-01-01

    The power systems for use in NASA space missions must work reliably under harsh conditions including radiation, thermal cycling, and exposure to extreme temperatures. Gallium nitride semiconductors show great promise, but information pertaining to their performance is scarce. Gallium nitride N-channel enhancement-mode field effect transistors made by EPC Corporation in a 2nd generation of manufacturing were exposed to radiation followed by long-term thermal cycling and testing under high temperature reverse bias conditions in order to address their reliability for use in space missions. Result of the experimental work are presented and discussed.

  20. Role of Oxidative Stress in the Induction of Metallothionein-2A and Heme Oxygenase-1 Gene Expression by the Antineoplastic Agent Gallium Nitrate in Human Lymphoma Cells

    Science.gov (United States)

    Yang, Meiying; Chitambar, Christopher R.

    2008-01-01

    The mechanisms of action of gallium nitrate, an antineoplastic drug, are only partly understood. Using a DNA microarray to examine genes induced by gallium nitrate in CCRF-CEM cells, we found that gallium increased metallothionein-2A (MT2A) and heme oxygenase-1 (HO-1) gene expression and altered the levels of other stress-related genes. MT2A and HO-1 were increased after 6 and 16 h of incubation with gallium nitrate. An increase in oxidative stress, evidenced by a decrease in cellular GSH and GSH/GSSG ratio, and an increase in dichlorodihydrofluoroscein (DCF) fluorescence, was seen after 1 – 4 h incubation of cells with gallium nitrate. DCF fluorescence was blocked by the mitochondria-targeted antioxidant mitoquinone. N-acetyl-L-cysteine blocked gallium-induced MT2A and HO-1 expression and increased gallium’s cytotoxicity. Studies with a zinc-specific fluoroprobe suggested that gallium produced an expansion of an intracellular labile zinc pool, suggesting an action of gallium on zinc homeostasis. Gallium nitrate increased the phosphorylation of p38 mitogen-activated protein kinase and activated Nrf-2, a regulator of HO-1 gene transcription. Gallium-induced Nrf-2 activation and HO-1 expression were diminished by a p38 MAP kinase inhibitor. We conclude that gallium nitrate induces cellular oxidative stress as an early event which then triggers the expression of HO-1 and MT2A through different pathways. PMID:18586083

  1. Dissolved scandium, yttrium, and lanthanum in the surface waters of the North Atlantic: Potential use as an indicator of scavenging intensity

    Science.gov (United States)

    Till, C. P.; Shelley, R. U.; Landing, W. M.; Bruland, K. W.

    2017-08-01

    Recent work has begun to elucidate the biogeochemical cycling of scandium (Sc) in the open ocean, but so far no surface distribution data have been reported of dissolved Sc, and no basin-scale surface distributions have been reported of yttrium (Y) or lanthanum (La). This work presents basin-wide surface Sc, Y, and La data in a section across the North Atlantic subtropical gyre (2011 GEOTRACES GA03) and investigates the potential utility of these distributions. This work uses dissolved and aerosol concentration data for La and Sc to estimate their surface ocean residence times in both the center of the oligotrophic gyre and near the African coastline. This work additionally shows that the surface distribution of Sc in the North Atlantic correlates with the shape of the gyre as inferred by isotherm depth, with lower Sc concentrations at the gyre boundaries. This pattern suggests that Sc could be drawn down by the elevated particle flux at the gyre boundaries. In this case, Sc removal could be used as an indicator of scavenging intensity. In order to account for variable input of Sc to the surface ocean, we propose normalizing the Sc distribution to that of Y or La, which are much less particle reactive and are input via dust to the surface North Atlantic in constant ratios with Sc. Such normalization improves the correlation with isotherm depth. We propose that the variations in dissolved Y/Sc and La/Sc ratios may be due to preferential Sc scavenging and could therefore indicate scavenging intensity.

  2. On new ternary equiatomic scandium transition metal aluminum compounds ScTAl with T = Cr, Ru, Ag, Re, Pt, and Au

    Energy Technology Data Exchange (ETDEWEB)

    Radzieowski, Mathis; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Benndorf, Christopher [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Haverkamp, Sandra [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; University of Sao Paulo, Sao Carlos, SP (Brazil). Inst. of Physics

    2016-08-01

    The new equiatomic scandium transition metal aluminides ScTAl for T = Cr, Ru, Ag, Re, Pt, and Au were obtained by arc-melting of the elements followed by subsequent annealing for crystal growth. The samples were studied by powder and single crystal X-ray diffraction. The structures of three compounds were refined from single crystal X-ray diffractometer data: ScCrAl, MgZn{sub 2} type, P6{sub 3}/mmc, a = 525.77(3), c = 858.68(5) pm, R{sub 1} = 0.0188, wR{sub 2} = 0.0485, 204 F{sup 2} values, 13 variables, ScPtAl, TiNiSi type, Pnma, a = 642.83(4), b = 428.96(2), c = 754.54(5) pm, R{sub 1} = 0.0326, wR{sub 2} = 0.0458, 448 F{sup 2} values, 20 variables and ScAuAl, HfRhSn type, P anti 62c, a = 722.88(4), c = 724.15(4) pm, R{sub 1} = 0.0316, wR{sub 2} = 0.0653, 512 F{sup 2} values, 18 variables. Phase pure samples of all compounds were furthermore investigated by magnetic susceptibility measurements, and Pauli-paramagnetism but no superconductivity was observed down to 2.1 K for all of them. The local structural features and disordering phenomena have been characterized by {sup 27}Al and {sup 45}Sc magic angle spinning (MAS) and static NMR spectroscopic investigations.

  3. The influence of cation ordering, oxygen vacancy distribution and proton siting on observed properties in ceramic electrolytes: the case of scandium substituted barium titanate.

    Science.gov (United States)

    Torino, Nico; Henry, Paul F; Knee, Christopher S; Bjørheim, Tor Svendsen; Rahman, Seikh M H; Suard, Emma; Giacobbe, Carlotta; Eriksson, Sten G

    2017-07-04

    The origin of the 2-order of magnitude difference in the proton conductivity of the hydrated forms of hexagonal and cubic oxygen deficient BaScxTi1-xO3-δ (x = 0.2 and x = 0.7) was probed using a combination of neutron diffraction and density functional theory techniques to support published X-ray diffraction, conductivity, thermogravimetric and differential scanning calorimetry studies. Cation ordering is found in the 6H structure type (space group P63/mmc) adopted by BaSc0.2Ti0.8O3-δ with scandium preferentially substituting in the vertex sharing octahedra (2a crystallographic site) and avoiding the face-sharing octahedra (4f site). This is coupled with oxygen vacancy ordering in the central plane of the face-sharing octahedra (O1 site). In BaSc0.7Ti0.3O3-δ a simple cubic perovskite (space group Pm3[combining macron]m) best represents the average structure from Rietveld analysis with no evidence of either cation ordering or oxygen vacancy ordering. Significant diffuse scattering is observed, indicative of local order. Hydration in both cases leads to complete filling of the available oxygen vacancies and permits definition of the proton sites. We suggest that the more localised nature of the proton sites in the 6H structure is responsible for the significantly lower proton conduction observed in the literature. Within the 6H structure type final model, proton diffusion requires a 3-step process via higher energy proton sites that are unoccupied at room temperature and is also likely to be anisotropic whereas the highly disordered cubic perovskite proton position allows 3-dimensional diffusion by well-described modes. Finally, we propose how this knowledge can be used to further materials design for ceramic electrolytes for proton conducting fuel cells.

  4. Photoelectrochemical etching of gallium nitride surface by complexation dissolution mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Miao-Rong [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou (China); University of Chinese Academy of Sciences, 100049 Beijing (China); Hou, Fei; Wang, Zu-Gang; Zhang, Shao-Hui [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou (China); Changchun University of Science and Technology, 130022 Changchun (China); Pan, Ge-Bo, E-mail: gbpan2008@sinano.ac.cn [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou (China)

    2017-07-15

    Graphical abstract: GaN surface was etched by 0.3 M EDTA-2Na. The proposed complexation dissolution mechanism can be applicable to almost all neutral etchants under the prerequisite of strong light and electric field. - Highlights: • GaN surface was etched by EDTA-2Na. • GaN may be dissolved into EDTA-2Na by forming Ga–EDTA complex. • We propose the complexation dissolution mechanism for the first time. - Abstract: Gallium nitride (GaN) surface was etched by 0.3 M ethylenediamine tetraacetic acid disodium (EDTA-2Na) via photoelectrochemical etching technique. SEM images reveal the etched GaN surface becomes rough and irregular. The pore density is up to 1.9 × 10{sup 9} per square centimeter after simple acid post-treatment. The difference of XPS spectra of Ga 3d, N 1s and O 1s between the non-etched and freshly etched GaN surfaces can be attributed to the formation of Ga–EDTA complex at the etching interface between GaN and EDTA-2Na. The proposed complexation dissolution mechanism can be broadly applicable to almost all neutral etchants under the prerequisite of strong light and electric field. From the point of view of environment, safety and energy, EDTA-2Na has obvious advantages over conventionally corrosive etchants. Moreover, as the further and deeper study of such nearly neutral etchants, GaN etching technology has better application prospect in photoelectric micro-device fabrication.

  5. Gallium enhances reconstructive properties of a calcium phosphate bone biomaterial.

    Science.gov (United States)

    Strazic Geljic, Ivana; Melis, Nicolas; Boukhechba, Florian; Schaub, Sébastien; Mellier, Charlotte; Janvier, Pascal; Laugier, Jean-Pierre; Bouler, Jean-Michel; Verron, Elise; Scimeca, Jean-Claude

    2018-02-01

    Calcium phosphate (CaP)-based biomaterials are commonly used in bone reconstructive surgery to replace the damaged tissue, and can also serve as vectors for local drug delivery. Due to its inhibitory action on osteoclasts, the semi-metallic element gallium (Ga) is used for the systemic treatment of disorders associated with accelerated bone resorption. As it was demonstrated that Ga could be incorporated in the structure of CaP biomaterials, we investigated the biological properties of Ga-loaded CaP biomaterials. Culturing bone cells on Ga-CaP, we observed a decrease in osteoclast number and a downregulation of late osteoclastic markers expression, while Ga-CaP upregulated the expression of osteoblastic marker genes involved in the maturation of bone matrix. We next investigated in vivo bone reconstructive properties of different Ga-loaded biomaterials using a murine bone defect healing model. All implanted biomaterials showed a good osseointegration into the surrounding host tissue, accompanied by a successful bone ingrowth and bone marrow reconstruction, as evidenced by histological analysis. Moreover, quantitative micro-computed tomography analysis of implants revealed that Ga enhanced total defect filling. Lastly, we took advantage for the first time of a particular mode of non-linear microscopy (second harmonic generation) to quantify in vivo bone tissue reconstruction within a CaP bone substitute. By doing so, we showed that Ga exerted a positive impact on mature organized collagen synthesis. As a whole, our data support the hypothesis that Ga represents an attractive additive to CaP biomaterials for bone reconstructive surgery. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  6. Supersonic jet epitaxy of gallium nitride using triethylgallium and ammonia

    Science.gov (United States)

    McGinnis, Arthur J.; Thomson, Darren; Banks, Andrew; Preble, Edward; Davis, Robert F.; Lamb, H. Henry

    2003-01-01

    Gallium nitride (GaN) films were grown on GaN(0001)/AlN/6H-SiC composite substrates at 700-780 °C by supersonic jet epitaxy using triethylgallium (TEG) and NH3. TEG was seeded in He and N2 supersonic free jets to obtain kinetic energies of ~2.1 and ~0.5 eV, respectively, and NH3 was supplied from a variable leak valve. Higher TEG beam intensities (by about a factor of 5) were obtained by seeding in He. In situ reflection high-energy electron diffraction indicated a transition from three-dimensional to two-dimensional (2D) growth between 730 and 750 °C for films grown using TEG seeded in He and a constant NH3/TEG flux ratio. Ex situ atomic force microscopy of films grown at 730 and 750 °C revealed smooth surfaces comprised of quasi-2D islands with irregular perimeters. Cross-sectional transmission electron microscopy evidenced that the film grown at 750 °C was homoepitaxial α-GaN with a high density of planar lattice defects. Secondary ion mass spectrometry detected high residual carbon concentrations in the films. The GaN growth rate at 750 °C was found to depend on TEG flux and NH3 pressure in a manner consistent with Langmuir-Hinshelwood kinetics. Films grown under NH3-rich conditions were faceted and microscopically rough, whereas nonfaceted, basal-plane growth was observed under Ga-rich conditions. The first-order dependence of growth rate on TEG flux under NH3-rich conditions was used to estimate Ga incorporation efficiencies for high- and low-energy TEG beams. The Ga incorporation efficiency is lower for high-energy TEG beams, consistent with a decrease in the sticking coefficient for dissociative chemisorption.

  7. Sensor of hydrostatic pressure based on gallium antimonide microcrystals

    Directory of Open Access Journals (Sweden)

    Druzhinin A. A.

    2015-08-01

    Full Text Available Currently, silicon and germanium, the most common materials in the production of discrete semiconductor devices and integrated circuits, do not always meet all the requirements to the sensing elements of mechanical quantities sensors. Therefore, it is logical to research the properties of other semiconductor materials that could be used as sensing elements in such sensors. A3B5 semiconductor compounds seem promising for such purpose. Effect of hydrostatic pressure up to 5000 bar on the resistance of n-type antimonide gallium whiskers doped by Se or Te was studied. Coefficient of hydrostatic pressure for this crystals was determined, it equals Kh = (16,5—20,0•10–5 bar–1 at 20°N. Temperature dependence of resistance and coefficient Kh for this crystals in the temperature range ±60°N was studied. Design of the developed hydrostatic pressure sensor based on GaSb whiskers and its characteristics are presented. The possibility to decrease the temperature dependence of sensitive element resistance by mounting GaSb whiskers on the substrates fabricated from materials with different temperature coefficient of expansion was examined. It was shown that mounting of GaSb crystals on Cu substrate gives the optimal result, in this case the temperature coefficient decrease to 0,05%•°N–1, that leads to decrease of output temperature dependence. The main advantages of developed pressure sensor are: the simplified design in comparison with pressure sensors with strain gauges mounted on spring elements; the high sensitivity to pressure that is constant in the wide pressure range; the improvement of sensors metrological characteristics owing to hysteresis absence. The possible application fields of developed sensors are measuring of high and extremely high pressure, chemical and oil industries, measuring of pressure in oil bore-holes, investigation of explosive processes.

  8. Isolation and characterization of gallium resistant Pseudomonas aeruginosa mutants.

    Science.gov (United States)

    García-Contreras, Rodolfo; Lira-Silva, Elizabeth; Jasso-Chávez, Ricardo; Hernández-González, Ismael L; Maeda, Toshinari; Hashimoto, Takahiro; Boogerd, Fred C; Sheng, Lili; Wood, Thomas K; Moreno-Sánchez, Rafael

    2013-12-01

    Pseudomonas aeruginosa PA14 cells resistant to the novel antimicrobial gallium nitrate (Ga) were developed using transposon mutagenesis and by selecting spontaneous mutants. The mutants showing the highest growth in the presence of Ga were selected for further characterization. These mutants showed 4- to 12-fold higher Ga minimal inhibitory growth concentrations and a greater than 8-fold increase in the minimum biofilm eliminating Ga concentration. Both types of mutants produced Ga resistant biofilms whereas the formation of wild-type biofilms was strongly inhibited by Ga. The gene interrupted in the transposon mutant was hitA, which encodes a periplasmic iron binding protein that delivers Fe³⁺ to the HitB iron permease; complementation of the mutant with the hitA gene restored the Ga sensitivity. This hitA mutant showed a 14-fold decrease in Ga internalization versus the wild-type strain, indicating that the HitAB system is also involved in the Ga uptake. Ga uptake in the spontaneous mutant was also lower, although no mutations were found in the hitAB genes. Instead, this mutant harbored 64 non-silent mutations in several genes including those of the phenazine pyocyanin biosynthesis. The spontaneous mutant produced 2-fold higher pyocyanin basal levels than the wild-type; the addition of this phenazine to wild-type cultures protected them from the Ga bacteriostatic effect. The present data indicate that mutations affecting Ga transport and probably pyocyanin biosynthesis enable cells to develop resistance to Ga. Copyright © 2013 Elsevier GmbH. All rights reserved.

  9. Progress to a Gallium-Arsenide Deep-Center Laser

    Directory of Open Access Journals (Sweden)

    Janet L. Pan

    2009-10-01

    Full Text Available Although photoluminescence from gallium-arsenide (GaAs deep-centers was first observed in the 1960s, semiconductor lasers have always utilized conduction-to-valence-band transitions. Here we review recent materials studies leading to the first GaAs deep-center laser. First, we summarize well-known properties: nature of deep-center complexes, Franck-Condon effect, hotoluminescence. Second, we describe our recent work: insensitivity of photoluminescence with heating, striking differences between electroluminescence and photoluminescence, correlation between transitions to deep-states and absence of bandgap-emission. Room-temperature stimulated-emission from GaAs deep-centers was observed at low electrical injection, and could be tuned from the bandgap to half-the-bandgap (900–1,600 nm by changing the electrical injection. The first GaAs deep-center laser was demonstrated with electrical injection, and exhibited a threshold of less than 27 mA/cm2 in continuous-wave mode at room temperature at the important 1.54 μm fiber-optic wavelength. This small injection for laser action was explained by fast depopulation of the lower state of the optical transition (fast capture of free holes onto deep-centers, which maintains the population inversion. The evidence for laser action included: superlinear L-I curve, quasi-Fermi level separations satisfying Bernard-Duraffourg’s criterion, optical gains larger than known significant losses, clamping of the optical-emission from lossy modes unable to reach laser action, pinning of the population distribution during laser action.

  10. Indium Phosphide Window Layers for Indium Gallium Arsenide Solar Cells

    Science.gov (United States)

    Jain, Raj K.

    2005-01-01

    Window layers help in reducing the surface recombination at the emitter surface of the solar cells resulting in significant improvement in energy conversion efficiency. Indium gallium arsenide (In(x)Ga(1-x)As) 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 make this material very attractive for multi-bandgap energy, multi-junction solar cell approaches. The high efficiency and better radiation performance of the solar cell structures based on InGaAs make them suitable for space power applications. This work investigates the suitability of indium phosphide (InP) window layers for lattice-matched In(0.53)Ga(0.47)As (bandgap energy 0.74 eV) solar cells. We present the first data on the effects of the p-type InP window layer on p-on-n lattice-matched InGaAs solar cells. The modeled quantum efficiency results show a significant improvement in the blue region with the InP window. The bare InGaAs solar cell performance suffers due to high surface recombination velocity (10(exp 7) cm/s). The large band discontinuity at the InP/InGaAs heterojunction offers a great potential barrier to minority carriers. The calculated results demonstrate that the InP window layer effectively passivates the solar cell front surface, hence resulting in reduced surface recombination and therefore, significantly improving the performance of the InGaAs solar cell.

  11. Transferrin receptors and gallium-67 uptake in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.C.P.; Newman, B.; Turkall, R.M.; Tsan, M.F.

    1982-12-01

    The relationship was studied between the number of transferrin-receptor positive cells and in vitro uptake of /sup 67/Ga and /sup 125/I-labeled transferrin in human cell lines, including two normal cell lines (WI-38 and foreskin fibroblasts), two transformed cell lines (AV-3 amnionic cells and Chang liver cells), and two neoplastic cell lines (HEp-2, larynx cancer and HeLa, cervical cancer). Transferrin receptors were determined by an indirect immunofluoresence technique based on their ability to bind purified human transferrin. Gallium-67 uptake was determined after a 24-h incubation of cells with Ga-67 in the presence and absence of transferrin (0-2.5 mg/mI). /sup 125/I-labeled transferrin uptake was also obtained after a 24-h incubation. The fraction of cells with transferrin receptors was low in normal cell lines (3% and 9%), intermediate with transformed cell lines (33% and 49%), and high in neoplastic cell lines (59% and 61%). Transferrin stimulated /sup 67/Ga uptake by all six cell lines. However, there was poor correlation between the number of transferrin-receptor positive cells and /sup 67/Ga uptake either in the presence (r=0.21) or absence (r=0.46) of human transferrin. Likewise, there was poor correlation between the number of transferrin-receptor positive cells and /sup 125/I-labeled transferrin uptake (r=0.35). In contrast, the correlation between /sup 67/Ga uptake (in the presence of transferrin) and /sup 125/I-labeled transferrin uptake was highly significant (r=0.96). These results suggest that human cell lines in culture are capable of both transferrin-dependent and transferrin-independent uptake of /sup 67/Ga.

  12. Gallium-cladding compatibility testing plan: Phase 3 -- Test plan for centrally heated surrogate rodlet test. Revision 2

    Energy Technology Data Exchange (ETDEWEB)

    Morris, R.N.; Baldwin, C.A.; Wilson, D.F.

    1998-07-01

    The Fissile Materials Disposition Program (FMDP) is investigating the use of weapons grade plutonium in mixed oxide (MOX) fuel for light-water reactors (LWR). Commercial MOX fuel has been successfully used in overseas reactors for many years; however, weapons derived fuel may differ from the previous commercial fuels because of small amounts of gallium impurities. A concern presently exists that the gallium may migrate out of the fuel, react with and weaken the clad, and thereby promote loss of fuel pin integrity. Phases 1 and 2 of the gallium task are presently underway to investigate the types of reactions that occur between gallium and clad materials. This is a Level-2 document as defined in the Fissile Materials Disposition Program Light-Water Reactor Mixed-Oxide Fuel Irradiation Test Project Plan. This Plan summarizes the projected Phase 3 Gallium-Cladding compatibility heating test and the follow-on post test examination (PTE). This work will be performed using centrally-heated surrogate pellets, to avoid unnecessary complexities and costs associated with working with plutonium and an irradiation environment. Two sets of rodlets containing pellets prepared by two different methods will be heated. Both sets will have an initial bulk gallium content of approximately 10 ppm. The major emphasis of the PTE task will be to examine the material interactions, particularly indications of gallium transport from the pellets to the clad.

  13. Iron-Targeting Antitumor Activity of Gallium Compounds and Novel Insights Into Triapine®-Metal Complexes

    Science.gov (United States)

    Antholine, William E.

    2013-01-01

    Abstract Significance: Despite advances made in the treatment of cancer, a significant number of patients succumb to this disease every year. Hence, there is a great need to develop new anticancer agents. Recent Advances: Emerging data show that malignant cells have a greater requirement for iron than normal cells do and that proteins involved in iron import, export, and storage may be altered in cancer cells. Therefore, strategies to perturb these iron-dependent steps in malignant cells hold promise for the treatment of cancer. Recent studies show that gallium compounds and metal-thiosemicarbazone complexes inhibit tumor cell growth by targeting iron homeostasis, including iron-dependent ribonucleotide reductase. Chemical similarities of gallium(III) with iron(III) enable the former to mimic the latter and interpose itself in critical iron-dependent steps in cellular proliferation. Newer gallium compounds have emerged with additional mechanisms of action. In clinical trials, the first-generation-compound gallium nitrate has exhibited activity against bladder cancer and non-Hodgkin's lymphoma, while the thiosemicarbazone Triapine® has demonstrated activity against other tumors. Critical Issues: Novel gallium compounds with greater cytotoxicity and a broader spectrum of antineoplastic activity than gallium nitrate should continue to be developed. Future Directions: The antineoplastic activity and toxicity of the existing novel gallium compounds and thiosemicarbazone-metal complexes should be tested in animal tumor models and advanced to Phase I and II clinical trials. Future research should identify biologic markers that predict tumor sensitivity to gallium compounds. This will help direct gallium-based therapy to cancer patients who are most likely to benefit from it. Antioxid. Redox Signal. 00, 000–000. PMID:22900955

  14. Iron-targeting antitumor activity of gallium compounds and novel insights into triapine(®)-metal complexes.

    Science.gov (United States)

    Chitambar, Christopher R; Antholine, William E

    2013-03-10

    Despite advances made in the treatment of cancer, a significant number of patients succumb to this disease every year. Hence, there is a great need to develop new anticancer agents. Emerging data show that malignant cells have a greater requirement for iron than normal cells do and that proteins involved in iron import, export, and storage may be altered in cancer cells. Therefore, strategies to perturb these iron-dependent steps in malignant cells hold promise for the treatment of cancer. Recent studies show that gallium compounds and metal-thiosemicarbazone complexes inhibit tumor cell growth by targeting iron homeostasis, including iron-dependent ribonucleotide reductase. Chemical similarities of gallium(III) with iron(III) enable the former to mimic the latter and interpose itself in critical iron-dependent steps in cellular proliferation. Newer gallium compounds have emerged with additional mechanisms of action. In clinical trials, the first-generation-compound gallium nitrate has exhibited activity against bladder cancer and non-Hodgkin's lymphoma, while the thiosemicarbazone Triapine(®) has demonstrated activity against other tumors. Novel gallium compounds with greater cytotoxicity and a broader spectrum of antineoplastic activity than gallium nitrate should continue to be developed. The antineoplastic activity and toxicity of the existing novel gallium compounds and thiosemicarbazone-metal complexes should be tested in animal tumor models and advanced to Phase I and II clinical trials. Future research should identify biologic markers that predict tumor sensitivity to gallium compounds. This will help direct gallium-based therapy to cancer patients who are most likely to benefit from it.

  15. Rare evidence for formation of garnet + corundum during isobaric cooling of ultrahigh temperature metapelites: New insights for retrograde P-T trajectory of the Highland Complex, Sri Lanka

    Science.gov (United States)

    Dharmapriya, P. L.; Malaviarachchi, Sanjeeva P. K.; Galli, Andrea; Su, Ben-Xun; Subasinghe, N. D.; Dissanayake, C. B.

    2015-04-01

    We report the occurrence of coexisting garnet + corundum in spinel- and corundum-bearing, garnet-sillimanite-biotite-graphite gneiss (pelitic granulites) from the Highland Complex (HC), Sri Lanka. In the investigated pelitic granulites, two domains such as quartz-saturated and quartz-undersaturated are distinguishable. The quartz-saturated domains consist of porphyroblastic garnet, quartz, plagioclase, alkali-feldspar and biotite flakes rimming garnet. The quartz-undersaturated domains are constituted of two generations of garnet (Grt1 and Grt2), sillimanite, plagioclase, alkali-feldspar, corundum, spinel and biotite. Grt1 encloses rare Ti-rich biotite and numerous rutile needles and apatite rods. Grt2 contains rare sillimanite and/or spinel inclusions. Corundum occurs in mutual contact with Grt2, partially embedded at the rim or as an inclusions in Grt2. Thermobarometry on inclusion phases in Grt1 indicates that during the prograde history pelitic granulites attained a P of 10.5-11 kbar at T of ~ 850 °C. Textural observations coupled with both pseudosections calculated in the NCKFMASHTMnO system and Ti-in-Garnet geothermobarometry suggest that peak metamorphism occurred at ultrahigh temperature (UHT) conditions of 950-975 °C and pressures of 9-9.5 kbar. Peak T was followed by a period of isobaric cooling that formed corundum and Grt2 at approx. 930 °C along with exsolution of rutile needles and apatite rods in Grt1. Thermodynamic modelling confirms that corundum appears along an isobaric cooling path at about 920-930 °C and 9-9.5 kbar. Therefore, the investigated granulites provide a rare example of post-peak crystallization of garnet + corundum along a retrograde metamorphic trajectory under UHT conditions. Thus, isobaric cooling at the base of the crust could be regarded as an alternative process to form coexisting garnet + corundum.

  16. Wavelength dependence of light diffusion in strongly scattering macroporous gallium phosphide

    NARCIS (Netherlands)

    Peeters, W.H.; Vellekoop, Ivo Micha; Mosk, Allard; Lagendijk, Aart

    2008-01-01

    We present time-resolved measurements of light transport through strongly scattering macroporous gallium phosphide at various vacuum wavelengths between 705 nm and 855 nm. Within this range the transport mean free path is strongly wavelength dependent, whereas the observed energy velocity is shown

  17. Impact of atmospheric species on copper indium gallium selenide solar cell stability: An overview

    NARCIS (Netherlands)

    Theelen, M.

    2016-01-01

    An overview of the measurement techniques and results of studies on the stability of copper indium gallium selenide (CIGS) solar cells and their individual layers in the presence of atmospheric species is presented: in these studies, Cu(In,Ga)Se2 solar cells, their molybdenum back contact, and their

  18. Gallium(III) and indium(III) dithiolate complexes: Versatile precursors ...

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. The chemistry of classical and organometallic complexes of gallium and indium with di- thiolate ligands, i.e., dithiocarboxylates, xanthates, dithiocarbamates, dithiophosphates, dithiophophinates and dithioarsenates, has been reviewed. Synthesis, spectroscopic and structural aspects of these com- plexes are ...

  19. Infected cyst localization with gallium SPECT imaging in polycystic kidney disease

    Energy Technology Data Exchange (ETDEWEB)

    Amesur, P.; Castronuovo, J.J.; Chandramouly, B.

    1988-01-01

    This case report describes a 43-year-old woman with polycystic renal disease and cyst infection. Infected cysts of the left kidney were successfully localized with Ga-67 citrate SPECT imaging and CT. Other imaging, including planar gallium imaging, was helpful diagnostically, but could not determine the exact location of infection within the kidney.

  20. Low Temperature Flux Growth of 2H-SiC and Beta-Gallium Oxide

    Science.gov (United States)

    Singh, N. B.; Choa, Fow-Sen; Su, Ching-Hua; Arnold, Bradley; Kelly, Lisa

    2016-01-01

    We present brief overview of our study on the low temperature flux growth of two very important novel wide bandgap materials 2H-SiC and Beta-gallium oxide (Beta-Ga2O3). We have synthesized and grown 5 millimeter to 1 centimeter size single crystals of Beta-gallium oxide (Beta-Ga2O3). We used a flux and semi wet method to grow transparent good quality crystals. In the semi-wet method Ga2O3 was synthesized with starting gallium nitrate solution and urea as a nucleation agent. In the flux method we used tin and other metallic flux. This crystal was placed in an alumina crucible and temperature was raised above 1050 degrees Centigrade. After a time period of thirty hours, we observed prismatic and needle shaped crystals of gallium oxide. Scanning electron microscopic studies showed step growth morphology. Crystal was polished to measure the properties. Bandgap was measured 4.7electronvolts using the optical absorption curve. Another wide bandgap hexagonal 2H-SiC was grown by using Si-Al eutectic flux in the graphite crucible. We used slight AlN also as the impurity in the flux. The temperature was raised up to 1050 degrees Centigrade and slowly cooled to 850 degrees Centigrade. Preliminary characterization results of this material are also reported.