Neodymium isotopic study of rare earth element sources and mobility in hydrothermal Fe-oxide (Fe-P-REE) systems

NASA Astrophysics Data System (ADS)

Gleason, James D.; Marikos, Mark A.; Barton, Mark D.; Johnson, David A.

2000-03-01

Rare earth element (REE)-enriched, igneous-related hydrothermal Fe-oxide hosted (Fe-P-REE) systems from four areas in North America have been analyzed for their neodymium isotopic composition to constrain REE sources and mobility in these systems. The Nd isotopic results evidence a common pattern of REE concentration from igneous sources despite large differences in age (Proterozoic to Tertiary), tectonic setting (subduction vs. intraplate), and magmatic style (mafic vs. felsic). In the Middle Proterozoic St. Francois Mountains terrane of southeastern Missouri, ɛ Nd for Fe-P-REE (apatite, monazite, xenotime) deposits ranges from +3.5 to +5.1, similar to associated felsic to intermediate igneous rocks of the same age (ɛ Nd = +2.6 to +6.2). At the mid-Jurassic Humboldt mafic complex in western Nevada, ɛ Nd for Fe-P-REE (apatite) mineralization varies between +1.1 and +2.4, similar to associated mafic igneous rocks (-1.0 to +3.5). In the nearby Cortez Mountains in central Nevada, mid-Jurassic felsic volcanic and plutonic rocks (ɛ Nd = -2.0 to -4.4) are associated with Fe-P-REE (apatite-monazite) mineralization having similar ɛ Nd (-1.7 to -2.4). At Cerro de Mercado, Durango, Mexico, all assemblages analyzed in this Tertiary rhyolite-hosted Fe oxide deposit have identical isotopic compositions with ɛ Nd = -2.5. These data are consistent with coeval igneous host rocks being the primary source of REE in all four regions, and are inconsistent with a significant contribution of REE from other sources. Interpretations of the origin of these hydrothermal systems and their concomitant REE mobility must account for nonspecialized igneous sources and varied tectonic settings.

Neodymium isotopic study of rare earth element sources and mobility in hydrothermal Fe oxide (Fe-P-REE) systems

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

Gleason, J.D.; Marikos, M.A.; Barton, M.D.

2000-03-01

Rare earth element (REE)-enriched, igneous-related hydrothermal Fe-oxide hosted (Fe-P-REE) systems from four areas in North America have been analyzed for their neodymium iosotopic composition to constrain REE sources and mobility in these systems. The Nd isotopic results evidence a common pattern of REE concentration from igneous sources despite large differences in age (Proterozoic to Tertiary), tectonic setting (subduction vs. intraplate), and magmatic style (mafic vs. felsic). In the Middle Proterozoic St. Francois Mountains terrane of southeastern Missouri, {epsilon}{sub Nd} for Fe-P-REE (apatite, monazite, xenotime) deposits ranges from +3.5 to +5.1, similar to associated felsic to intermediate igneous rocks of themore » same age ({epsilon}{sub Nd} = +2.6 to +6.2). At the mid-Jurassic Humboldt mafic complex in western Nevada, {epsilon}{sub Nd} for Fe-P-REE (apatite) mineralization varies between +1.1 and +2.4, similar to associated mafic igneous rocks ({minus}1.0 to +3.5). In the nearby Cortez Mountains in central Nevada, mid-Jurassic felsic volcanic and plutonic rocks ({epsilon}{sub Nd} = {minus}2.0 to {minus}4.4) are associated with Fe-P-REE (apatite-monazite) mineralization having similar {epsilon}{sub Nd}({minus}1.7 to {minus}2.4). At Cerro de Mercado, Durango, Mexico, all assemblages analyzed in this Tertiary rhyolite-hosted Fe oxide deposit have identical isotopic compositions with {epsilon}{sub Nd} = {minus}2.5. These data are consistent with coeval igneous host rocks being the primary source of REE in all four regions, and are inconsistent with a significant contribution of REE from other sources. Interpretations of the origin of these hydrothermal systems and their concomitant REE mobility must account for nonspecialized igneous sources and varied tectonic settings.« less

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

PubMed

Andreasen, Rasmus; Sharma, Mukul

2006-11-03

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

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

PubMed

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

2006-08-01

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

Abundance analysis of neodymium in the solar atmosphere

NASA Astrophysics Data System (ADS)

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

2017-10-01

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

Perovskite catalysts for oxidative coupling

DOEpatents

Campbell, K.D.

1991-06-25

Perovskites of the structure A[sub 2]B[sub 2]C[sub 3]O[sub 10] are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

Perovskite catalysts for oxidative coupling

DOEpatents

Campbell, Kenneth D.

1991-01-01

Perovskites of the structure A.sub.2 B.sub.2 C.sub.3 O.sub.10 are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

Antioxidant protection mechanism of chick hepatic mitochondria exposed to lanthanum chloride & neodymium chloride treatment.

PubMed

Ghosh, N; Chattopadhyay, D; Chatterjee, G C

1991-05-01

Acute lanthanum chloride (250 mg/kg body wt) and neodymium chloride (200 mg/kg body wt) administrations resulted in significant enhancement of glutathione level in chick hepatic mitochondria. However, glutathione-s-transferase activity was depressed. There was no alteration in the activity of glutathione reductase. Activity of glucose-6-phosphate dehydrogenase was not altered under lanthanum and neodymium treatment. There was a significant enhancement of intramitochondrial glutathione peroxidase and superoxide dismutase. Lipid peroxidation remains the same as control group of animals.

Neodymium: YAG lasers. An FDA report.

PubMed

Stark, W J; Worthen, D; Holladay, J T; Murray, G

1985-02-01

Analysis of data from four neodymium:YAG laser manufacturers submitted to the Food and Drug Administration (FDA) on over 17,000 cases indicate the procedure is safe and effective for cutting opaque posterior lens capsules. A successful opening in the pupillary membrane was achieved in 98% of the cases, and vision improved in 84% of the cases. Clinically significant risks include: a rise in intraocular pressure two to four hours after treatment, damage to the intraocular lens, and rupture of the anterior hyaloid face.

Neodymium:YAG laser cutting of intraocular lens haptics.

PubMed

Gorn, R A; Steinert, R F

1985-11-01

Neodymium:YAG laser cutting of polymethylmethacrylate and polypropylene anterior chamber and posterior chamber intraocular lens haptics was studied in terms of ease of transection and physical structure of the cut areas as seen by scanning electron microscopy. A marked difference was discovered, with the polymethylmethacrylate cutting easily along transverse planes, whereas the polypropylene resisted cutting along longitudinal fibers. Clinical guidelines are presented.

Effect Of Neodymium Substitution In Structural Characteristics Of Magnesium Ferrite

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

Thankachan, Smitha; Binu, P. J.; Xavier, Sheena

2011-10-20

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

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

DOEpatents

Marling, John B.

1977-01-01

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

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

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

Rosal, Blanca del; Pérez-Delgado, Alberto; Rocha, Ueslen

2015-10-14

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

Nanostructured silicon ferromagnet collected by a permanent neodymium magnet.

PubMed

Okuno, Takahisa; Thürmer, Stephan; Kanoh, Hirofumi

2017-11-30

Nanostructured silicon (N-Si) was prepared by anodic electroetching of p-type silicon wafers. The obtained magnetic particles were separated by a permanent neodymium magnet as a magnetic nanostructured silicon (mN-Si). The N-Si and mN-Si exhibited different magnetic properties: the N-Si exhibited ferromagnetic-like behaviour, whereas the mN-Si exhibited superparamagnetic-like behaviour.

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

ERIC Educational Resources Information Center

Mattson, Bruce

2007-01-01

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

Demonstrating and Measuring Relative Molar Magnetic Susceptibility Using a Neodymium Magnet

ERIC Educational Resources Information Center

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

2004-01-01

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

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

PubMed

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

2015-05-01

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

X-ray emission from a plasma mirror of a neodymium glass laser

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

Kalal, M.; Pina, L.; Vrbova, M.

1984-11-01

An investigation was made of the optical and x-ray characteristics of the radiation emitted by a plasma mirror in a neodymium glass laser. The optical reflection coefficient of the mirror was found to be nonlinear and the plasma temperature was about 300 eV.

Lattice thermal expansion and solubility limits of neodymium-doped ceria

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

Zhang, Jinhua, E-mail: jhzhang1212@126.com; State Key laboratory of Geological Process and Mineral Resources, China University of Geosciences, Wuhan 430074; Ke, Changming

2016-11-15

Nd{sub x}Ce{sub 1−x}O{sub 2−0.5x} (x=0–1.0) powders were prepared by reverse coprecipitation-calcination method and characterized by XRD. The crystal structure of product powders transformed from single fluorite structure to the complex of fluorite and C-type cubic structure, and finally to trigonal structure with the increase of x-value. An empirical equation simulating the lattice parameter of neodymium doped ceria was established based on the experimental data. The lattice parameters of the fluorite structure solid solutions increased with extensive adoption of Nd{sup 3+}, and the heating temperature going up. The average thermal expansion coefficients of neodymium doped ceria with fluorite structure are highermore » than 13.5×10{sup −6} °C{sup −1} from room temperature to 1200 °C. - Graphical abstract: The crystal structure of Nd{sub x}Ce{sub 1−x}O{sub 2−0.5x} (x=0–1.0) powders transformed from single fluorite structure to the complex of fluorite and C-type cubic structure, and finally to trigonal structure with the increase of x-value.« less

A green separation strategy for neodymium (III) from cobalt (II) and nickel (II) using an ionic liquid-based aqueous two-phase system.

PubMed

Chen, Yuehua; Wang, Huiyong; Pei, Yuanchao; Wang, Jianji

2018-05-15

It is significant to develop sustainable strategies for the selective separation of rare earth from transition metals from fundamental and practical viewpoint. In this work, an environmentally friendly solvent extraction approach has been developed to selectively separate neodymium (III) from cobalt (II) and nickel (II) by using an ionic liquid-based aqueous two phase system (IL-ATPS). For this purpose, a hydrophilic ionic liquid (IL) tetrabutylphosphonate nitrate ([P 4444 ][NO 3 ]) was prepared and used for the formation of an ATPS with NaNO 3 . Binodal curves of the ATPSs have been determined for the design of extraction process. The extraction parameters such as contact time, aqueous phase pH, content of phase-formation components of NaNO 3 and the ionic liquid have been investigated systematically. It is shown that under optimal conditions, the extraction efficiency of neodymium (III) is as high as 99.7%, and neodymium (III) can be selectively separated from cobalt (II) and nickel (II) with a separation factor of 10 3 . After extraction, neodymium (III) can be stripped from the IL-rich phase by using dilute aqueous sodium oxalate, and the ILs can be quantitatively recovered and reused in the next extraction process. Since [P 4444 ][NO 3 ] works as one of the components of the ATPS and the extractant for the neodymium, no organic diluent, extra etractant and fluorinated ILs are used in the separation process. Thus, the strategy described here shows potential in green separation of neodymium from cobalt and nickel by using simple IL-based aqueous two-phase system. Copyright © 2018 Elsevier B.V. All rights reserved.

High surface area neodymium phosphate nano particles by modified aqueous sol-gel method

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

Sankar, Sasidharan; Warrier, Krishna Gopakumar, E-mail: wwarrierkgk@yahoo.co.in; Komban, Rajesh

2011-12-15

Graphical abstract: Synthesis of nano rod shaped neodymium phosphate particles with specific surface area as high as 107 m{sup 2} g{sup -1} and particles could be compacted and sintered at as low as 1300 Degree-Sign C to a density of 98.5% (theoretical) with an average grain size of {approx}1 {mu}m. Highlights: Black-Right-Pointing-Pointer Nano size neodymium phosphate is synthesized and characterized using a novel modified aqueous sol gel process. Black-Right-Pointing-Pointer Specific surface area above 100 m{sup 2} g{sup -1} achieved without the addition of any complexing agents. Black-Right-Pointing-Pointer High sintered density reported than the density obtained for powder synthesized through conventionalmore » solid state reaction. Black-Right-Pointing-Pointer The particles are nano sized and have rod shape morphology and are retained at higher temperatures. Black-Right-Pointing-Pointer An average grain size of {approx}1 {mu}m obtained for sintered NdPO{sub 4} after thermal etching at 1400 Degree-Sign C. -- Abstract: Synthesis of nano rod shaped neodymium phosphate (NdPO{sub 4}) particles with specific surface area as high as 107 m{sup 2}g{sup -1} and an average length of 50 nm with aspect ratio 5 was achieved using modified sol gel method. Crystallite size calculated from the X-ray diffraction data by applying Scherer equation was 5 nm for the precursor gel after calcination at 400 Degree-Sign C. NdPO{sub 4} was first precipitated from neodymium nitrate solution using phosphoric acid followed by peptization using dilute nitric acid and further gelation in ammonia atmosphere. The calcined gel powders were further characterized by surface area (Brunauer-Emmet-Teller nitrogen adsorption analysis), Transmission electron microscopy, scanning electron microscopy, UV-vis and FT-IR analysis. Transmission electron microscopy confirms the formation of rod like morphology from the sol, gel and the calcined particles in nano size range. These particles could be

Neodymium:yttrium-aluminum-garnet laser fusion of endarterectomy flaps.

PubMed

Humphrey, P W; Slocum, M M; Loy, T S; Silver, D

1995-07-01

This study evaluated the efficacy of neodymium:yttrium-aluminum-garnet laser welding of flaps in canine arteries and in securing the distal flap during human carotid endarterectomy. Endarterectomy flaps were created in both common carotid and both common femoral arteries in 12 dogs. The flaps were repaired with either the neodymium:yttrium-aluminum-garnet laser or with 6-0 polypropylene sutures. The arteries were removed after duplex scanning at either 7 or 28 days. Eighteen high carotid endarterectomy flaps in 16 patients have been subsequently secured with the laser welding technique. Laser repairs (125 +/- 19 joule) of the canine arteries were completed more quickly than suture repairs (mean 25 seconds vs 135 seconds, respectively; p < 0.04). Duplex ultrasonography revealed no discernable differences between the two groups of arteries. Arteries studied at 7 days revealed three microscopic flaps (two suture, one laser), more subintimal fibroblastic proliferation in suture than laser-repaired carotid arteries (3: 1, p = 0.0530), and similar amounts of inflammation in suture- and laser-repaired arteries. Arteries studied at 28 days revealed one microscopic intimal flap (suture-repaired); equal fibroblastic and inflammatory responses in suture- and laser-repaired vessels; and no evidence of laser thermal injury. Eighteen carotid endarterectomy flaps have been successfully fused with no immediate or long-term complications in 16 patients (follow-up of 0 to 24 months). Laser fusion appears to be a safe and effective method for securing distal carotid endarterectomy flaps.

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

PubMed

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

2009-04-01

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

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

NASA Astrophysics Data System (ADS)

Hart, Matthew

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

Development of High Temperature Superconducting Josephson Junction Device Technology

DTIC Science & Technology

1998-07-09

neodymium gallate , cerium oxide-buffered sapphire, and lanthanum aluminate, are not ideal for an in situ thallium cuprate junction technology. Moreover...determined that the standard HTS substrates, neodymium gallate , cerium oxide-buffered sapphire, and lanthanum aluminate, are not ideal for an in situ...2.2.1. Deposition Uniformity 10 2.2.2. Radiative Element 12 2.3. SUBSTRATES 13 2.3.1. Neodymium gallate 14 2.3.2. Cerium Oxide-Buffered Sapphire 16

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

PubMed

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

2016-09-01

Theranostic nanoplatforms integrate therapeutic payloads with diagnostic agents, and help monitor therapeutic response. In this regard, stimuli responsive nanoplatforms further favour combinatorial therapeutic approach that can considerably improve efficacy and specificity of treatment. Herein, we present the engineering of a smart theranostic nanoplatform based on neodymium doped hydroxyapatite (HAN). The presence of neodymium endows the HAN nanoplatforms with near-infrared fluorescence capability. These HAN nanoparticles were then subsequently modified with alginic acid (HANA) to confer pH responsiveness to the synthesized nanoplatforms delivering them to the colon after oral administration. These nanoplatforms possessing optimum size, needle shaped morphology and negative zeta potential, are conducive to cellular internalization. On excitation at 410nm they exhibit near infrared emission at 670nm unraveling their theranostic capabilities. Cytotoxic effects systematically assessed using MTT and live dead assays reveal excellent viability. Raman microscopic imaging technique used to visualize uptake in HeLa cells demonstrate increased uptake from 4 to 16h, with growing cluster size and localization in the cytoplasm. Moreover the concomitant presence of alginic acid manifested advantages of augmented loading and pH dependent release profiles of the model drug, 4 acetyl salicylic acid (4ASA). We could thus establish a theranostic system for early tumour detection, targeted tumour therapy and monitoring of colon cancer that can be administered via the oral route. Copyright © 2016 Elsevier B.V. All rights reserved.

Charge transfer in rare earth oxide hybrid solar cells revealed through ultrafast spectroscopic measurement

NASA Astrophysics Data System (ADS)

Pandit, Bill; Fernando, Kasun; Alphenaar, Bruce; Liu, Jinjun

2014-03-01

Hybrid inorganic-organic solar cells typically combine a transition metal oxide (such as TiO2) and organic dye or polymer absorber to form the donor acceptor pair. Here, Oxidized neodymium (Nd2O3) particles are combined with [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) to form the active layer of a bulk heterojunction solar cell. The addition of the Nd2O3 results in an enhancement in the short circuit current and open circuit voltage compared to pure PCBM. We also studied the ultrafast dynamics of photoexcitation in pristine PCBM film, and their blends with the rare earth oxide neodymium particles using the pump-probe photomodulation (PM) spectroscopy with ~30 fs time resolution. Our transient PM spectrum covers spectral range of 430 nm to 730 nm. Although the spectra of Nd2O3/PCBM are very similar with pristine PCBM, the recombination kinetics of photogenerated excitons decay rate increases with the addition of Nd2O3, and ground state photobleaching is also observed. Taken together this provides evidence for the charge transfer between the organic and rare earth inorganic components. Supported by the DOE-EPSCoR fund DOE BES (DE-FG02-07ER46375) at University of Louisville.

Determination of trace amounts of rare-earth elements in highly pure neodymium oxide by sector field inductively coupled plasma mass spectrometry (ICP-SFMS) and high-performance liquid chromatography (HPLC) techniques

NASA Astrophysics Data System (ADS)

Pedreira, W. R.; Sarkis, J. E. S.; da Silva Queiroz, C. A.; Rodrigues, C.; Tomiyoshi, I. A.; Abrão, A.

2003-02-01

Recently rare-earth elements (REE) have received much attention in fields of geochemistry and industry. Rapid and accurate determinations of them are increasingly required as industrial demands expand. Sector field inductively coupled plasma mass spectrometry (ICP-SFMS) with high-performance liquid chromatography (HPLC) has been applied to the determination of REE. HR ICP-MS was used as an element-selective detector for HPLC in highly pure materials. The separation of REE with HPLC helped to avoid erroneous analytical results due to spectral interferences. Sixteen elements (Sc, Y and 14 lanthanides) were determined selectively with the HPLC/ICP-SFMS system using a concentration gradient methods. The detection limits with the HPLC/ICP-SFMS system were about 0.5-10 pg mL-1. The percentage recovery ranged from 90% to 100% for different REE. The %RSD of the methods varying between 2.5% and 4.5% for a set of five (n=5) replicates was found for the IPEN's material and for the certificate reference sample. Determination of trace REEs in two highly pure neodymium oxides samples (IPEN and Johnson Matthey Company) were performed. In short, the IPEN's materials which are highly pure (>99.9%) were successfully analyzed without spectral interferences.

Electrochemical extraction of neodymium by co-reduction with aluminum in LiCl-KCl molten salt

NASA Astrophysics Data System (ADS)

Yan, Yong-De; Xu, Yan-Lu; Zhang, Mi-Lin; Xue, Yun; Han, Wei; Huang, Ying; Chen, Qiong; Zhang, Zhi-Jian

2013-02-01

The electrochemical behavior of Nd(III) ions in LiCl-KCl and LiCl-KCl-AlCl3 melts on a Mo electrode at 723 K was studied by various electrochemical techniques. The results showed that Nd(III) ions are reduced to Nd(0) through two consecutive steps, and the underpotential deposition of neodymium on pre-deposited Al electrode formed two kinds of Al-Nd intermetallic compounds in LiCl-KCl-AlCl3 solutions. The electrochemical extraction of neodymium was carried out in LiCl-KCl-AlCl3 melts on a Mo electrode at 873 K by potentiostatic and galvanostatic electrolysis. The extraction efficiency was 99.25% after potentiostatic electrolysis for 30 h. Al-Li-Nd bulk alloy was obtained by galvanostatic electrolysis. X-ray diffraction (XRD) suggested that Al2Nd and Al3Nd phases were formed in Al-Li-Nd alloy. The microstructure and micro-zone chemical analysis of Al-Li-Nd alloy were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), respectively.

[The first experience with the concurrent effect of YAG-neodymium and YAG-erbium laser on experimental animal tissues and the possibility of its use in surgery].

PubMed

Roshal', L M; Gorbatova, N E; Livshits, Iu L; Parkhomenko, Iu G; Osiko, V V; Danileĭko, Iu K; Sidorin, A V; Tylaĭkova, T B; Ivanov, A D

1991-08-01

To guarantee the necessary rate of cutting live tissues with adequate hemostasis along the line of the incision, the authors studied isolated and joint effect of radiations of AIG-neodymium and AIG-erbium lasers on the tissues of laboratory animals. The possibility of accomplishing intraoperative hemostasis on the parenchymal organs was studied in experiments with AIG-neodymium laser. A good dissection effect in cutting various tissues was produced in the second series of experiments with AIG-erbium laser. The simultaneous action of AIG-neodymium and AIG-erbium beams converged at one point on the surface of the biological object was studied in the third series of experiments. It was found that the effect ensures a good dissection of tissues with sufficient hemostasis. The results of dynamic morphological studies are shown. The possibility of using the device in surgery is discussed.

LASERS: Ultimate energy parameters of the radiation emitted from neodymium-glass laser systems

NASA Astrophysics Data System (ADS)

Eshmemet'eva, E. V.; Korolev, V. I.; Mesnyankin, E. P.; Serebryakov, V. A.; Shashkin, V. V.; Yashin, V. E.

1992-09-01

An experimental investigation was made of the energy conversion efficiency and of the effects of stimulated Brillouin scattering and of optical breakdown, limiting the maximum energy density obtained from several phosphate and silicate neodymium glasses when the duration of the output pulses was 50-150 ns. The experimental results were used to develop a numerical model for calculation of the gain allowing for these processes. A design was developed for an amplifier with ultimate radiation characteristics.

Watt-level single-frequency tunable neodymium MOPA fiber laser operating at 915-937 nm

NASA Astrophysics Data System (ADS)

Rota-Rodrigo, S.; Gouhier, B.; Laroche, M.; Zhao, J.; Canuel, B.; Bertoldi, A.; Bouyer, P.; Traynor, N.; Cadier, B.; Robin, T.; Santarelli, G.

2018-02-01

We have developed a Watt-level single-frequency tunable fiber laser in the 915-937 nm spectral window. The laser is based on a neodymium-doped fiber master oscillator power amplifier architecture, with two amplification stages using a 20 mW extended cavity diode laser as seed. The system output power is higher than 2 W from 921 to 933 nm, with a stability better than 1.4% and a low relative intensity noise.

UV and fluorescence spectral changes induced by neodymium binding of N,N'-ethylenebis[2-(o-hydroxyphenolic)glycine] and N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N' diacetic acid.

PubMed

Wang, Zhijun; Yang, Binsheng

2006-11-01

In 0.01 M 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (Hepes), pH 7.4 and room temperature, the binding of neodymium to N,N'-ethylenebis[2-(o-hydroxyphenolic)glycine] (EHPG), or N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N' diacetic acid (HBED) had been studied from 210 to 330 nm by means of difference UV spectra. Two peaks at 240 and 292 nm appear in difference UV spectra after neodymium binding to EHPG or HBED. The 1:1 stable complex can be confirmed from spectral titration curves. The molar extinction coefficient of Nd-EHPG and Nd-HBED complexes are Deltaepsilon(Nd-EHPG)=(12.93+/-0.21) x 10(3)cm(-1)M(-1), Deltaepsilon(Nd-HBED)=(14.45+/-0.51) x 10(5)cm(-1)M(-1) at 240 nm, respectively. Using EDTA as a competitor, the conditional equilibrium constants of the complexes are logK(Nd-EHPG)=11.89+/-0.09 and logK(Nd-HBED)=12.19+/-0.15, respectively. At the same conditions, fluorescence measurements show that neodymium binding to EHPG leads to a quenching of the fluorescence of EHPG at near 310 nm. However, there is no obvious fluorescence change of HBED at 318 nm with the binding of neodymium to HBED.

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

PubMed

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

2012-06-15

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

Neodymium Isotope Variations in Late Quaternary Carbonate Lake Sediments, Owens Valley, Eastern California.

NASA Astrophysics Data System (ADS)

Minervini, J. M.; Stewart, B. W.

2001-12-01

Owens Lake is situated in a mostly-closed basin fed by water and sediments derived primarily from the eastern Sierra Nevada range. Chemical and sedimentological variations in USGS Owens Lake Core OL-92, which extends back 800 ka, have been shown to be sensitive tracers of Great Basin paleoclimate. Here we report preliminary neodymium (Nd) isotope data from core OL-92 to investigate sediment provenance, the chemical behavior of rare earth elements (REE) in non-marine systems, and possible climate-related shifts in weathering patterns of the eastern Sierra Nevada during the last glacial-interglacial transition. Neodymium isotopic analyses were carried out on the carbonate fraction of sediment samples ranging in age from 16.8 to 6.9 ka from Owens Lake core OL-92. Samples were treated with ammonium acetate to remove exchangeable cations from coexisting silicate material, and subsequently leached with 8% acetic acid to dissolve carbonate minerals. Based on the mass of sediment leached with acetic acid, the fraction of carbonate (relative to clastic silicate material) increases from 6.6 to 66.5% over the 10 ka period represented by these samples. This increase in carbonate reflects desiccation of the Owens Lake basin; as streamwater flow is reduced, the lake spends a greater proportion of its time saturated in carbonate minerals, and clastic input might also be reduced. Concentrations of Nd in Owens Lake carbonate range from 7 to 170 ppm, values that are 2-1000 times higher than marine planktonic foraminifera (e.g., Vance and Burton, 1999, EPSL 173, 365). In general, high concentrations of Nd in Owens Lake carbonate are associated with older sediment samples with lower carbonate fractions. The decrease in Nd concentration over this time period could be a result of extraction of Nd from lake waters by precipitation of carbonate as desiccation proceeded. Epsilon-Nd values of Owens Lake carbonate range from -5.3 to -6.5, and are consistent with eastern Sierra Nevada

Solid-state reaction kinetics of neodymium doped magnesium hydrogen phosphate system

NASA Astrophysics Data System (ADS)

Gupta, Rashmi; Slathia, Goldy; Bamzai, K. K.

2018-05-01

Neodymium doped magnesium hydrogen phosphate (NdMHP) crystals were grown by using gel encapsulation technique. Structural characterization of the grown crystals has been carried out by single crystal X-ray diffraction (XRD) and it revealed that NdMHP crystals crystallize in orthorhombic crystal system with space group Pbca. Kinetics of the decomposition of the grown crystals has been studied by non-isothermal analysis. The estimation of decomposition temperatures and weight loss has been made from the thermogravimetric/differential thermo analytical (TG/DTA) in conjuncture with DSC studies. The various steps involved in the thermal decomposition of the material have been analysed using Horowitz-Metzger, Coats-Redfern and Piloyan-Novikova equations for evaluating various kinetic parameters.

A supported liquid membrane system for the selective recovery of rare earth elements from neodymium-based permanent magnets

DOE PAGES

Kim, Daejin; Powell, Lawrence; Delmau, Lætitia H.; ...

2016-04-04

We present that the rare earth elements (REEs) play a vital role in the development of green energy and high-tech industries. In order to meet the fast-growing demand and to ensure sufficient supply of the REEs, it is essential to develop an efficient REE recovery process from post-consumer REE-containing products. In this research effort, we have developed a supported liquid membrane system utilizing polymeric hollow fiber modules to extract REEs from neodymium-based magnets with neutral extractants such as tetraoctyl digylcol amide (TODGA). The effect of process variables such as REE concentration, molar concentration of acid, and membrane area on REEmore » recovery was investigated. We have demonstrated the selective extraction and recovery of REEs such as Nd, Pr, and Dy without co-extraction of non-REEs from permanent NdFeB magnets through the supported liquid membrane system. The extracted REEs were then recovered by precipitation followed by the annealing step to obtain crystalline REE powders in nearly pure form. Finally, the recovered REE oxides were characterized by X-ray diffraction, scanning electron microscope coupled with energy-dispersive X-ray spectroscopy, and inductively coupled plasma–optical emission spectroscopy.« less

Femtosecond diode-pumped mode-locked neodymium lasers

NASA Astrophysics Data System (ADS)

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

2016-12-01

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

Global mining risk footprint of critical metals necessary for low-carbon technologies: the case of neodymium, cobalt, and platinum in Japan.

PubMed

Nansai, Keisuke; Nakajima, Kenichi; Kagawa, Shigemi; Kondo, Yasushi; Shigetomi, Yosuke; Suh, Sangwon

2015-02-17

Meeting the 2-degree global warming target requires wide adoption of low-carbon energy technologies. Many such technologies rely on the use of precious metals, however, increasing the dependence of national economies on these resources. Among such metals, those with supply security concerns are referred to as critical metals. Using the Policy Potential Index developed by the Fraser Institute, this study developed a new footprint indicator, the mining risk footprint (MRF), to quantify the mining risk directly and indirectly affecting a national economy through its consumption of critical metals. We formulated the MRF as a product of the material footprint (MF) of the consuming country and the mining risks of the countries where the materials are mined. A case study was conducted for the 2005 Japanese economy to determine the MF and MRF for three critical metals essential for emerging energy technologies: neodymium, cobalt and platinum. The results indicate that in 2005 the MFs generated by Japanese domestic final demand, that is, the consumption-based metal output of Japan, were 1.0 × 10(3) t for neodymium, 9.4 × 10(3) t for cobalt, and 2.1 × 10 t for platinum. Export demand contributes most to the MF, accounting for 3.0 × 10(3) t, 1.3 × 10(5) t, and 3.1 × 10 t, respectively. The MRFs of Japanese total final demand (domestic plus export) were calculated to be 1.7 × 10 points for neodymium, 4.5 × 10(-2) points for cobalt, and 5.6 points for platinum, implying that the Japanese economy is incurring a high mining risk through its use of neodymium. This country's MRFs are all dominated by export demand. The paper concludes by discussing the policy implications and future research directions for measuring the MFs and MRFs of critical metals. For countries poorly endowed with mineral resources, adopting low-carbon energy technologies may imply a shifting of risk from carbon resources to other natural resources, in particular critical metals, and a trade

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

PubMed Central

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

2015-01-01

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

Synthesis of 0.1% & 0.2% neodymium doped barium zirconium titanate (BaZr{sub 0.2}Ti{sub 0.8}O{sub 3}) and study of their dielectric behaviour

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

Kumar, Anil, E-mail: anilkantikumar@rediffmail.com; Kumar, Vipin; Gupta, Merry

2015-08-28

Efforts have been made to ease process of producing widely used multilayered ceramics of Barium Zirconium Titanium Oxides and study their dielectric behaviour and structural properties. For this purpose, adequate proportions of Barium Carbonate, Zirconium Oxide and Titanium Oxide were taken and hand milled for 2 hours. Neodymium composition of the order of 0.1% and 0.2% was used for doping to weight percentage of BaZr0.2Ti0.8O3. The samples were authenticated using raw data obtained from Bruker AXS D8 advance Copper KL alpha source XRD equipment. Further, the samples were studied for their phase transition, composition, single phase perovskite structure using XRDmore » technique. The technique has also been applied to know formation of stable homogeneous solid solution from XRD parameters. The other physical parameters like the morphology, micro structural information, crystal arrangements and topography have also been observed through SEM. The SEM has revealed information related to grain size development and composition of sample with fine agglomerates. For complete study of the compounds the atomic and weight composition has also been examined by Electron Dispersive Spectroscopy patterns. The comparison has been made with other works on ceramics at various frequencies and has yielded very interesting results.« less

Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.

PubMed

Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank

2015-01-01

Rare earth elements are promising alloying element candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare earth elements have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth element concentrations. We showed that low concentrations of rare earth elements do not promote bone growth inside a 750 μm broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium-rare earth element alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Liquid-liquid extraction of neodymium(III) by dialkylphosphate ionic liquids from acidic medium: the importance of the ionic liquid cation.

PubMed

Rout, Alok; Kotlarska, Justyna; Dehaen, Wim; Binnemans, Koen

2013-10-21

The ionic liquids 1-hexyl-3-methylimidazolium bis(2-ethylhexyl)phosphate, [C6mim][DEHP], 1-hexyl-1-methylpyrrolidinium bis(2-ethylhexyl)phosphate, [C6mpyr][DEHP], and tetrabutylammonium bis(2-ethylhexyl)phosphate, [N4444][DEHP], were prepared and characterized using (1)H and (13)C NMR spectroscopy. The extraction behavior of neodymium(iii) from nitrate medium by these ionic liquids, diluted with the room temperature ionic liquids 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C6mim][NTf2], 1-hexyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [C6mpyr][NTf2], and tributylmethylammonium bis(trifluoromethylsulfonyl)imide, [N1444][NTf2], was studied. The distribution ratio of neodymium(iii) was measured as a function of various parameters, such as pH, concentration of the ionic liquid extractant, nature of diluents, concentration of ionic liquid cations and nitrate anions in the aqueous phase. The extraction behavior was compared with that obtained for a solution of the molecular extractant bis(2-ethylhexyl)phosphoric acid (DEHPA) in an ionic liquid diluent. The extraction of neodymium(iii) in the ionic liquids [C6mim][DEHP] and [C6mpyr][DEHP] showed markedly different extraction properties in comparison with that of the quaternary ammonium analogue [N4444][DEHP], especially concerning the pH dependence of the extraction process. These results show that the extraction process can be tuned by the selection of the ionic liquid cation. The extraction experiments also included the trivalent rare-earth ions lanthanum(iii), cerium(iii), praseodymium(iii), ytterbium(iii) and yttrium(iii). Studies of the stripping behavior and the reusability of the ionic liquids were carried out, which indicate that the ionic liquids can be reused with no loss in activity.

Power scaling of diode-pumped neodymium yttrium aluminum borate laser

NASA Technical Reports Server (NTRS)

Hemmati, Hamid

1991-01-01

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

Electrochemistry and the mechanisms of nucleation and growth of neodymium during electroreduction from LiCl-KCl eutectic salts on Mo substrate

NASA Astrophysics Data System (ADS)

Tang, Hao; Pesic, Batric

2015-03-01

The electrochemical behavior of NdCl3 was studied on a Mo electrode in molten LiCl-KCl eutectic salts. The electroreduction of Nd(III)/Nd(0) involved two reaction steps, as confirmed by three different electrochemical techniques. In the first reaction step, Nd(III) is converted into soluble Nd(II), which undergoes further reduction into metallic Nd(0) in the second reaction step. The standard reaction rate constants for each reaction step were determined by Nicholson method. The rate constant values were used in Matsuda-Ayabe's criteria for testing the electrochemical reversibility. Accordingly, both reaction steps were quasi-reversible redox reactions. The nucleation mechanisms of neodymium metal deposited on a Mo substrate were predicted by using Scharifker-Hill model, and tested for the first time by scanning electron microscopy (SEM) studies of the electrode surface. The SEM studies confirmed that for the low initial concentration of NdCl3, neodymium nucleates and grows progressively, while for higher NdCl3 concentrations, the related mechanism is instantaneous. Both are governed by the aggregative growth mechanisms based on surface mobility of formed nanoclusters.

Developing a Magnetic Circular Dichroism Apparatus Equipped with Neodymium Magnet for Students to Investigate the Electronic Structures of Transition Metals and Lanthanoids

ERIC Educational Resources Information Center

Yakubu, Abdallah; Suzuki, Takayoshi; Kita, Masakazu

2017-01-01

This paper describes the development of a simple magnetic circular dichroism (MCD) apparatus from a wood base and neodymium magnets and its configuration in the Faraday alignment. The applicability and effectiveness of the apparatus for MCD spectra measurements have been examined. The apparatus was used by undergraduate students to conduct MCD…

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

NASA Astrophysics Data System (ADS)

Jeandel, Catherine; Thouron, Danièle; Fieux, Michèle

1998-08-01

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

Neodymium isotopes in biogenic carbonates: reliable archives of ɛNd

NASA Astrophysics Data System (ADS)

Montagna, P.; Goldstein, S. L.; Taviani, M.; Frank, N.; McCulloch, M. T.

2010-12-01

Neodymium isotope (143Nd/144Nd) compositions from dispersed authigenic ferromanganese oxide fraction in marine sediments, ferromanganese crusts, foraminiferal shells and fossil fish teeth are employed to trace provenance and water mass mixing in the past, having the advantage of not being fractionated by biological processes in the water column. In the modern ocean the different water masses ultimately derive their ɛNd values through continental weathering, erosion and particle-seawater interactions. This geochemical tracer has been only recently applied to scleractinian deep-water coral skeletons sourced from various sites and depths in the Atlantic ocean. Aragonitic corals can be precisely dated by U-series, potentially providing century-long records of intermediate and bathyal zone variability at sub-decadal resolution. Motivated by these recent findings we have investigated the Nd isotopic compositions of living specimens of various calcifying organisms collected in two key locations of the Mediterranean Sea and in the Southern Ocean. In particular, we analyzed several specimens of the aragonitic deep-water corals Desmophyllum dianthus, Lophelia pertusa, Madrepora oculata, Flabellum impensum, the temperate coral Cladocora caespitosa, the calcitic gorgonian coral Corallium rubrum, the bivalves Glans aculeata and Karnekampia bruei and the polychate Serpula vermicularis. Most of the samples were retrieved from the Strait of Sicily and the Southern Adriatic Sea at different water depths. Ten seawater samples from three new profiles in the Mediterranean were also collected at the same locations and depths, offering a unique opportunity to compare the Nd isotopic composition of biogenic carbonates directly with the surrounding ambient seawater. The Mediterranean Sea is particularly suited for this comparison exercise since it is characterized by water masses displaying a large range of ɛNd values, from -10.5 in the Western Mediterranean to -4.8 in the Eastern

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

PubMed Central

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

2016-01-01

The neodymium (Nd) isotopic composition of seawater has been used extensively to reconstruct ocean circulation on a variety of time scales. However, dissolved neodymium concentrations and isotopes do not always behave conservatively, and quantitative deconvolution of this non-conservative component can be used to detect trace metal inputs and isotopic exchange at ocean–sediment interfaces. In order to facilitate such comparisons for historical datasets, we here provide an extended global database for Nd isotopes and concentrations in the context of hydrography and nutrients. Since 2010, combined datasets for a large range of trace elements and isotopes are collected on international GEOTRACES section cruises, alongside classical nutrient and hydrography measurements. Here, we take a first step towards exploiting these datasets by comparing high-resolution Nd sections for the western and eastern North Atlantic in the context of hydrography, nutrients and aluminium (Al) concentrations. Evaluating those data in tracer–tracer space reveals that North Atlantic seawater Nd isotopes and concentrations generally follow the patterns of advection, as do Al concentrations. Deviations from water mass mixing are observed locally, associated with the addition or removal of trace metals in benthic nepheloid layers, exchange with ocean margins (i.e. boundary exchange) and/or exchange with particulate phases (i.e. reversible scavenging). We emphasize that the complexity of some of the new datasets cautions against a quantitative interpretation of individual palaeo Nd isotope records, and indicates the importance of spatial reconstructions for a more balanced approach to deciphering past ocean changes. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’. PMID:29035258

Global flows of critical metals necessary for low-carbon technologies: the case of neodymium, cobalt, and platinum.

PubMed

Nansai, Keisuke; Nakajima, Kenichi; Kagawa, Shigemi; Kondo, Yasushi; Suh, Sangwon; Shigetomi, Yosuke; Oshita, Yuko

2014-01-01

This study, encompassing 231 countries and regions, quantifies the global transfer of three critical metals (neodymium, cobalt, and platinum) considered vital for low-carbon technologies by means of material flow analysis (MFA), using trade data (BACI) and the metal contents of trade commodities, resolving the optimization problem to ensure the material balance of the metals within each country and region. The study shows that in 2005 international trade led to global flows of 18.6 kt of neodymium, 154 kt of cobalt, and 402 t of platinum and identifies the main commodities and top 50 bilateral trade links embodying these metals. To explore the issue of consumption efficiency, the flows were characterized according to the technological level of each country or region and divided into three types: green ("efficient use"), yellow ("moderately efficient use"), and red ("inefficient use"). On this basis, the shares of green, yellow, and red flows in the aggregate global flow of Nd were found to be 1.2%, 98%, and 1.2%, respectively. For Co, the respective figures are 53%, 28%, and 19%, and for Pt 15%, 84%, and 0.87%. Furthermore, a simple indicator focusing on the composition of the three colored flows for each commodity was developed to identify trade commodities that should be prioritized for urgent technical improvement to reduce wasteful use of the metals. Based on the indicator, we discuss logical, strategic identification of the responsibilities and roles of the countries involved in the global flows.

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

PubMed

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

2014-03-15

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

Characterisation of Nd2O3 thick gate dielectric for silicon

NASA Astrophysics Data System (ADS)

Dakhel, A. A.

2004-03-01

Thin neodymium films were prepared by the reactive synthesis method on Si (P) substrates to form MOS devices. The oxide films were characterised by UV absorption spectroscopy, X-ray fluorescence (EDXRF) and X-ray diffraction (XRD). The ac conductance and capacitance of the devices were studied as a function of frequency in the range 100 Hz-100 kHz, of temperature in the range 293-473 K and of gate voltage. It was proved that a suitable formalism to explain the frequency dependence of the ac conductivity and capacitance of the insulator is controlled by a universal power law based on the relaxation processes of the hopping or tunnelling of the current carriers between equilibrium sites. The temperature dependence of the ac conductance at the accumulation state shows a small activation energy of about 0.07 eV for a MOS device with amorphous neodymium oxide. The temperature dependence of the accumulation capacitance for a MOS structure with crystalline neodymium oxide shows a maximum at about 390 K; such a maximum was not observed for the structure with amorphous neodymium oxide. The method of capacitance-gate voltage (C-Vg) measurements was used to investigate the effect of annealing in air and in vacuum on the surface density of states (Nss) at the insulator/semiconductor (I/S) interface. It was concluded that the density of surface states in the mid-gap increases by about five times while the density of the trapped charges in the oxide layer decreases by about eight times when the oxide crystallises into a polycrystalline structure.

Seawater-derived neodymium isotope records in the Chukchi Sea, western Arctic Ocean during Holocene: implications for oceanographic circulation

NASA Astrophysics Data System (ADS)

Lee, Borom; Nam, Seung-Il; Huh, Youngsook; Lee, Mi Jung

2015-04-01

Changes in oceanographic circulation in the Artic have a large influence on the global oceanic and climate system of the Earth through the geological times. In particular, freshwater input from the North Pacific to the western Arctic Ocean affects the Atlantic meridional overturning circulation (AMOC) after the opening of the Bering Strait. Seawater-derived neodymium isotope in marine sediments has been used as a proxy to trace the origin of water masses and oceanic circulation system. The global average residence time of Nd is shorter than the global ocean mixing time and dissolved Nd in seawater behaves quasi-conservatively. In the modern Arctic Ocean, the Nd isotope distribution is dominated by Atlantic source water, although the circum-Arctic riverine discharge and Pacific-derived waters also have noticeable impacts. In this study, we investigated seawater-derived neodymium isotope records from a sediment core recovered from the Chukchi Sea to understand the changes in hydrograhic circulation of the western Arctic during the Holocene. A gravity core, ARA02B 01A, was collected on the northern shelf of the Chukchi Sea (73°37.8939'N, 166°30.9838'W, ca. 111 m in water depth) during the RV Araon expedition in 2011. To obtain seawater-derived Nd records, we extracted Fe-Mn oxide coatings as an authigenic fraction from bulk sediments by leaching with acid-reducing solution after removing carbonate by leaching with acetic acid. Our preliminary results might show a general pattern of increasing radiogenic ɛNd values through Holocene intervals. Therefore, it implies that ɛNd results may be related with variations in the intensity of Bering Strait inflow during the last ~9.31 ka BP. The radiogenic trend was strongly pronounced from the late Holocene (ɛNd -7.23; ca. 8.84 ka BP) to the middle Holocene (ɛNd -4.78; ca. 6.18 ka BP) and vaguely during the middle Holocene. After 4.13 ka BP, ɛNd values were increased again from -4.86 to -4.03 at 0.57 ka BP. But 87Sr/86Sr

Models for the Immediate Environment of Ions in Aqueous Solutions of Neodymium Chloride

NASA Astrophysics Data System (ADS)

Smirnov, P. R.; Grechin, O. V.

2018-01-01

Radial distribution functions of neodymium chloride aqueous solutions in a wide range of concentrations under ambient conditions are calculated from experimental data obtained earlier via X-ray diffraction analysis. Different models of the structural organization of the system are developed. The optimum versions are determined by calculating theoretical functions for each model and comparing their fit to the experimental functions. Such quantitative characteristics of the immediate environment of Nd3+ and Cl- ions as coordination numbers, interparticle distances, and varieties of ion pairs are determined. It is shown that the average number of water molecules in the first coordination sphere of the cation falls from 9 to 6.2 as the concentration rises. The structure of the systems over the whole range of concentrations is determined by ion associates of the noncontact type.

Neodymium:YAG laser cutting of intraocular lens haptics in vitro and in vivo.

PubMed

Feder, J M; Rosenberg, M A; Farber, M D

1989-09-01

Various complications following intraocular lens (IOL) surgery result in explantation of the lenses. Haptic fibrosis may necessitate cutting the IOL haptics prior to removal. In this study we used the neodymium: YAG (Nd:YAG) laser to cut polypropylene and poly(methyl methacrylate) (PMMA) haptics in vitro and in rabbit eyes. In vitro we were able to cut 100% of both haptic types successfully (28 PMMA and 30 polypropylene haptics). In rabbit eyes we were able to cut 50% of the PMMA haptics and 43% of the polypropylene haptics. Poly(methyl methacrylate) haptics were easier to cut in vitro and in vivo than polypropylene haptics, requiring fewer shots for transection. Complications of Nd:YAG laser use frequently interfered with haptic transections in rabbit eyes. Haptic transection may be more easily accomplished in human eyes.

Thermochemistry of rare earth doped uranium oxides LnxU1-xO2-0.5x+y (Ln = La, Y, Nd)

NASA Astrophysics Data System (ADS)

Zhang, Lei; Navrotsky, Alexandra

2015-10-01

Lanthanum, yttrium, and neodymium doped uranium dioxide samples in the fluorite structure have been synthesized, characterized in terms of metal ratio and oxygen content, and their enthalpies of formation measured by high temperature oxide melt solution calorimetry. For oxides doped with 10-50 mol % rare earth (Ln) cations, the formation enthalpies from constituent oxides (LnO1.5, UO2 and UO3 in a reaction not involving oxidation or reduction) become increasingly exothermic with increasing rare earth content, while showing no significant dependence on the varying uranium oxidation state. The oxidation enthalpy of LnxU1-xO2-0.5x+y is similar to that of UO2 to UO3 for all three rare earth doped systems. Though this may suggest that the oxidized uranium in these systems is energetically similar to that in the hexavalent state, thermochemical data alone can not constrain whether the uranium is present as U5+, U6+, or a mixture of oxidation states. The formation enthalpies from elements calculated from the calorimetric data are generally consistent with those from free energy measurements.

The characterisation and application of a pulsed neodymium YAG laser DGV system to a time-varying high-speed flow

NASA Astrophysics Data System (ADS)

Thorpe, S. J.; Quinlan, N.; Ainsworth, R. W.

2000-10-01

Doppler Global Velocimetry (DGV) is a whole-field measurement technique which has attracted significant interest from the fluid-flow research community since its introduction in 1991. Practical implementations of the methodology have focused on two principal laser light sources: the argon ion laser, applied to steady state or slowly varying flows; and the pulsed neodymium YAG laser for the measurement of instantaneous velocity fields. However, the emphasis in the published literature has been very much on research using the argon laser. This paper reports the application of a Q-switched, injection-seeded neodymium YAG laser to the proven Oxford DGV system, and the use of this combination in a short duration unsteady high-speed flow. The pertinent characteristics of the apparatus are described, and the impact of these on the integrity of the resulting velocity measurements is presented. Adaptations to the commercial laser system that make it suitable for application to the measurement of transient high-speed flows are described. Finally, the application of this system to a short duration unsteady flow is described. This application is based on the flow found in a new type of transdermal drug delivery device, where particles of the drug material are projected at high speed through the skin. Whole-field velocities are recorded, and values as high as 800 m/ s are evident.

Laboratory and clinical experience with neodymium:YAG laser prostatectomy

NASA Astrophysics Data System (ADS)

Kabalin, John N.

1996-05-01

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

Neodymium glass laser with a phase conjugate mirror producing 220 J pulses at 0.02 Hz repetition rate.

PubMed

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

2014-08-25

For pumping multipetawatt Ti:sapphire laser facilities we developed a compact repetitively pulsed laser based on neodymium phosphate glass with pulse energy of 220 J, pulse repetition rate of 0.02 Hz, beam diameter of 43 mm, aperture fill factor of 0.8, and FWHM pulse duration of 30 ns. The phase distortions of laser radiation were compensated by optical phase conjugation via stimulated Brillouin scattering. The depolarization was reduced to 0.4% using linear compensation methods. The beam quality was 2.5 x diffraction limit (150 µrad).

Gadolinium and didymium (praseodymium/neodymium) cations as capture agents in lightmicroscopical histochemistry of acid and alkaline phosphatase.

PubMed

Halbhuber, K J; Zimmermann, N

1987-01-01

In previous papers, cerium and lanthanum based methods for light-microscopical detection of acid and alkaline phosphatase activity were proposed. In this paper, the usefulness of other lanthanide cations such as gadolinium and praseodymium/neodymium cations as capture agents in phosphatase histochemistry is tested. It is evident that phosphate ions were sufficiently trapped by these cations. According to the lead and silver multistep procedures earlier described it is possible to visualize alkaline phosphatase activity in the brush borders of the intestine or kidney as well as acid phosphatase activity in the lysosomes. These methods can be recommended.

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

PubMed

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

1988-06-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-01-01

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

Lithotripsy of gallstones by means of a quality-switched giant-pulse neodymium:yttrium-aluminum-garnet laser. Basic in vitro studies using a highly flexible fiber system.

PubMed

Hochberger, J; Gruber, E; Wirtz, P; Dürr, U; Kolb, A; Zanger, U; Hahn, E G; Ell, C

1991-11-01

The quality-switched neodymium:yttrium-aluminum-garnet laser represents a new instrument for athermal fragmentation of gallstones by transformation of optical energy into mechanical energy in the form of shock waves via local plasma formation. A highly flexible 300-micron fiber transmission system was used in basic investigations to determine the influence of varying pulse repetition rates (5-30 Hz) and pulse energies (15 and 20 mJ) on shock wave intensity and stone fragmentation in vitro for 105 biliary calculi of known size and chemical composition. After performance of 1200 shock wave pressure measurements using polyvinylidenefluoride hydrophones, stone fragmentation was analyzed by determination of fragment removal rates (volume of fragments removed per fragmentation time), ablation rates (mean volume removed per laser pulse), and median fragment sizes for each laser setting. With the quality-switched neodymium:yttrium-aluminum-garnet laser system, all concrements could be reliably disintegrated into small fragments (median diameter, 0.7-1.7 mm). Compared with pure cholesterol stones, a significantly higher fragment removal rate was achieved in cholesterol stones containing 30% calcium phosphate (P = 0.039), in cholesterol stones containing 20% pigment (P = 0.015), and in pure pigment stones (P = 0.007). Fragment removal rates, local shock wave pressures, and median grain sizes were significantly higher at a pulse energy of 20 mJ than with 15 mJ. Shock wave pressures showed a distinct dependence on pulse repetition rates at 20 mJ, yet not at 15 mJ. Because there is no evident hazard of thermal damage to tissue using the quality-switched neodymium:yttrium-aluminum-garnet laser, it appears to be a promising device for nonsurgical biliary stone therapy.

Neodymium Isotope associated with planktonic foraminifera as a proxy of deglacial changes in Pacific ocean circulation

NASA Astrophysics Data System (ADS)

Hu, R.

2015-12-01

Neodymium isotopes of ferromanganese oxide coatings precipitated on planktonic foraminifera have been intensively used as a proxy for water mass reconstruction in the deep Atlantic and Indian Ocean, but their suitability is not well constrained in the Pacific and may be affected by enhanced inputs and scavenging relative to advection. In this study, Nd isotopes and Rare Earth Element (REE) concentrations of planktonic foraminifera from ~60 sites widely distributed throughout the Pacific are presented. We found that the REE pattern associated with planktonic foraminifera in our study and Fe-Mn oxides/coatings in the global ocean have a common heavy REE depleted pattern when normalized to their ambient seawater due to preferential removal of light REEs onto particles relative to heavy REEs during scavenging. The core-top ɛNd results agree with the proximal seawater compositions, indicating that planktonic foraminiferal coatings can give a reliable record of past changes in bottom water Nd isotopes in the Pacific. A good correlation between foraminifera Nd isotopes and seawater phosphate suggests that Nd with a predominantly radiogenic isotopic composition was probably added gradually along continental boundaries so that the Nd isotopic composition change paralleled the accumulation of nutrients in the deep Pacific. By confirming Nd isotopes as a reliable water mass tracer in the Pacific Ocean, this proxy is then applied to reconstruct how the water mass circulation changes during the Last Glacial Maximum (LGM). Most of the cores in deep North Pacific show essentially invariant Nd isotopic compositions during the LGM compared with core-top values, suggesting that Nd isotope of Pacific end-member did not change during glacial times. However, the LGM Southwest Pacific cores have more radiogenic ɛNd than core-tops corroborating the previous findings of reduced inflow of North Atlantic Deep Water. The Eastern Equatorial Pacific cores above ~2 km showed consistently

Intracavity frequency doubling of a continuous-wave, diode-laser-pumped neodymium lanthanum scandium borate laser.

PubMed

Meyn, J P; Huber, G

1994-09-15

Neodymium-doped lanthanum scandium borate [Nd:LaSc(3)(BO(3))(4)] is a new material for efficient and compact diode-pumped solid-state lasers. A simple plane-plane 3-mm-long resonator is formed by a coated Nd(10%):LaSc(3)(BO(3))(4) crystal and a coated potassium titanyl phosphate (KTP) crystal. The second-harmonic output power at 531 nm is 522 mW at 2.05-W incident pump power of the diode laser. The corresponding optical efficiency is 25%, and the conversion efficiency from the fundamental to the second harmonic is 55%. The wellknown chaotic power fluctuations of intracavity frequency-doubled lasers (green problem) are avoided by use of a short KTP crystal, between 0.5 and 2 mm in length.

Anterior capsule relaxing incisions with neodymium:YAG laser for patients at high-risk for anterior capsule contraction.

PubMed

Hayashi, Ken; Yoshida, Motoaki; Hirata, Akira; Hayashi, Hideyuki

2011-01-01

To examine the effect of anterior capsule relaxing incisions created with a neodymium:YAG (Nd:YAG) laser on prevention of anterior capsule contraction after cataract surgery in high-risk patients. Hayashi Eye Hospital, Fukuoka, Japan. Randomized masked clinical trials. Patients at high risk for anterior capsule contraction had anterior capsule relaxing incisions in either eye 3 days postoperatively. The anterior capsule opening was measured using a Scheimpflug videophotography system (EAS-1000) immediately and 1, 3, and 6 months after capsulotomy, and the percentage reduction in area was calculated. The degree of intraocular lens (IOL) decentration and tilt, posterior capsule opacification (PCO), and other complications were also assessed. Of the 84 patients included, 30 had primary angle closure, 28 had pseudoexfoliation, and 26 had diabetic retinopathy. There was no significant difference in the mean opening area between fellow eyes at baseline. In patients with primary angle closure, the area was significantly greater and the percentage reduction in area was significantly less in the capsulotomy group than in the no-capsulotomy group (P≤.0428). In patients with pseudoexfoliation or diabetic retinopathy, the percentage reduction was significantly less in the capsulotomy group than in the no-capsulotomy group (P≤.0493), although there was no significant difference in area. No significant difference was found in IOL decentration or tilt, PCO, or incidence of other complications. Neodymium:YAG laser anterior capsule relaxing incisions in the early period after cataract surgery were effective in preventing anterior capsule contraction in high-risk patients and had no adverse effects. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

IDENTIFICATION OF NEODYMIUM IN THE APOGEE H -BAND SPECTRA

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

Hasselquist, Sten; Holtzman, Jon; Chojnowski, Drew

2016-12-10

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

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

PubMed Central

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

2015-01-01

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

[Effect of phosphate on the exchangeable form and the bioavailability of exogenous neodymium in soil].

PubMed

Xu, Z; Li, D; Yang, J; Peng, A

2001-05-01

Effects of phosphate on the exchangeable form and the bioavailability of exogenous neodymium (Nd) in soil were studied with 147Nd isotopic tracer. Exchangeable Nd was extracted with solution (pH8.2) of NaAc. The results indicated that Nd beyond 99.5% was adsorbed by soil whether phosphate exists in soil or not. Phosphate can precipitate dramatically Nd3+. And the Nd phosphate precipitates may set limits on the concentration of exchangeable Nd observed in soil. KH2PO4 ranging from 0.3 g.kg-1 to 1.5 g.kg-1 make a uniform impact on the exchangeable form of Nd. In addition, phosphate in soil can inhibit wheat seedling to absorb Nd. The concentration of exchangeable Nd is correlated significantly with the content of Nd in wheat seedling.

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

NASA Technical Reports Server (NTRS)

Kurweg, U. H.

1984-01-01

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

Effect of neodymium:YAG laser capsulotomy on visual function in patients with posterior capsule opacification and good visual acuity.

PubMed

Yotsukura, Erisa; Torii, Hidemasa; Saiki, Megumi; Negishi, Kazuno; Tsubota, Kazuo

2016-03-01

To evaluate the effect of neodymium:YAG (Nd:YAG) laser capsulotomy on the visual function in patients with posterior capsule opacification (PCO) and good visual acuity. Keio University Hospital, Tokyo, Japan. Observational case series. Eyes were evaluated that had previous cataract surgery with a clinical diagnosis of PCO requiring Nd:YAG laser capsulotomy regardless of a good corrected distance visual acuity (CDVA) (at least 20/20). The CDVA, 10% low contrast visual acuity (LCVA), wavefront aberrations from the 3rd to 6th order, and retinal straylight were measured before and after Nd:YAG laser capsulotomy. The study included 16 eyes of 16 patients (10 men, 6 women; mean age 69.5 years ± 9.3 [SD]). The mean CDVA, LCVA, and straylight after Nd:YAG laser capsulotomy improved significantly (P < .05). The root mean square (RMS) of the 3rd Zernike coefficients (S3) and the RMS of the total higher-order aberrations (HOAs) from the 3rd to 6th order decreased significantly after capsulotomy (P < .05). The straylight correlated significantly with the total HOAs (r = 0.727, P = .002) and S3 (r = 0.748, P = .001) before capsulotomy. Subjective symptoms resolved after capsulotomy in all cases. Neodymium:YAG laser capsulotomy enabled a significant improvement in visual function even in patients with PCO with good visual acuity. Straylight measurements might be useful to determine the indications for Nd:YAG laser capsulotomy when patients report visual disturbances without decreased visual acuity. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Long-pulsed neodymium:yttrium-aluminum-garnet laser treatment for hypertrophic port-wine stains on the lips.

PubMed

Kono, Taro; Frederick Groff, William; Chan, Henry H; Sakurai, Hiroyuki; Yamaki, Takashi

2009-03-01

Pulsed dye laser (PDL) treatment of hypertrophic port-wine stains (PWSs) on the lips has demonstrated poor efficacy and a potential risk of dyspigmentation. PDL-resistant hypertrophic PWS may require treatment with deeper penetrating lasers such as a 1064-nm neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. The objective of this clinical study was to evaluate the efficacy and safety of a Nd:YAG laser for the treatment of hypertrophic PWSs on the lips. Ten patients (four were male and six were female) with hypertrophic PWSs on the lips were recruited in this study. Eight patients showed good to excellent improvement without complications. In conclusion, the Nd:YAG laser is safe and effective for treating hypertrophic PWSs on the lips.

Formation, structural and optical characterization of neodymium doped-zinc soda lime silica based glass

NASA Astrophysics Data System (ADS)

Zamratul, M. I. M.; Zaidan, A. W.; Khamirul, A. M.; Nurzilla, M.; Halim, S. A.

New glass system of neodymium - doped zinc soda lime silica glass has been synthesized for the first time by melt-quenching of glass waste soda lime silica (SLS) with zinc oxide (ZnO) as precursor glass and Nd2O3 as dopant. In order to examine the effect of Nd3+ on the structural and optical properties, the prepared sample of structure [(ZnO)0.5(SLS)0.5](Nd2O3)x (x = 0, 1, 2, 3, 4 and 5 wt%) was characterized through X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-Vis spectroscopy (UV-Vis) and the photoluminescence (PL). XRD pattern justifies the amorphous nature of synthesized glasses. FTIR spectroscopy has been used to observe the structural evolution of ZnO4 and SiO4 groups. The UV-Vis-NIR absorption spectra reveals seven peaks centered at excitation of electron from ground state 4I9/2 to 4D3/2 + 4D5/2 (∼360 nm), 2G9/2 + 2D3/2 + 2P3/2(∼470 nm), 2K13/2 + 4G7/2 + 4G9/2 (∼523 nm), 4G5/2 + 2G7/2 (∼583 nm), 4F9/2 (∼678 nm), 4S3/2 + 4F7/2 (∼748 nm) and 4F5/2 + 2H9/2 (∼801 nm). PL spectra under the excitation of 800 nm display four emission bands centered at 531 nm, 598 nm, 637 nm and 671 nm corresponding to 4G7/2 → 4I9/2, (4G7/2 → 4I11/2, 4G5/2 → 4I9/2), (4G5/2 → 4I11/2) and (4G7/2 → 4I13/2, 4G5/2 → 4I11/2) respectively.

Optimization of diode-pumped doubly QML laser with neodymium-doped vanadate crystals at 1.34 μm

NASA Astrophysics Data System (ADS)

Zhang, Gang; Jiao, Zhiyong

2018-05-01

We present a theoretical model for a diode-pumped, 1.34 μm V3+:YAG laser that is equipped with an acoustic-optic modulator. The model includes the loss introduced by the acoustic-optic modulator combined with the physical properties of the laser resonator, the neodymium-doped vanadate crystals and the output coupler. The parameters are adjusted within a reasonable range to optimize the pulse output characteristics. A typical Q-switched and mode-locked Nd:Lu0.15Y0.85VO4 laser at 1.34 μm with acoustic-optic modulator and V3+:YAG is set up, and the experimental output characteristics are consistent with the theoretical simulation results.

Spectroscopic investigations of neodymium doped barium bismuth fluoroborate glasses

NASA Astrophysics Data System (ADS)

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

2018-06-01

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

The contact neodymium-yttrium aluminum garnet laser. A new approach to arthroscopic laser surgery.

PubMed

O'Brien, S J; Miller, D V

1990-03-01

Arthroscopic treatment of meniscal lesions has been modified as technological advances have occurred. However, alternatives to conventional arthroscopic cutting tools, including electrocautery and CO2 lasers, have thus far met with limited success. The recent development of a sapphire tip has enabled the use of the neodymium-yttrium aluminum garnet (Nd-YAG) laser in a contact mode in a saline medium. This study compares the biology of the Nd-YAG laser to that of electrocautery and scalpel techniques with respect to its effects on articular cartilage and the meniscus. The contact Nd-YAG laser has advantages over both scalpel and electrocautery with regard to its effects on articular cartilage. It also has significant biologic advantages over electrocautery for meniscal lesions. Although in its infancy in the clinical setting, the contact Nd-YAG laser represents the possible beginning of a new era for application of laser energy in arthroscopy.

NONLINEAR OPTICAL EFFECTS AND FIBER OPTICS: Pulsed neodymium amplifier with phase conjugation and direct amplification

NASA Astrophysics Data System (ADS)

Basov, N. G.; Efimkov, V. F.; Zubarev, I. G.; Kolobrodov, V. V.; Pastukhov, S. A.; Smirnov, M. G.; Sobolev, V. B.

1988-12-01

A study was made of the characteristics of an amplifier containing neodymium-activated silicate rods, 45 mm in diameter, used in direct amplification and phase conjugation systems. At low output energies the divergence of the output radiation in the presence of a phase-conjugating mirror was half ( ~ 10- 4 rad) that in the case of direct amplification. An increase in the output power caused the divergence to rise more rapidly in the presence of a phase-conjugating mirror, which was tentatively attributed to an earlier manifestation of large-scale self-focusing. Output energies of 130 J in the case of direct amplification and 80 J in the presence of a phase-conjugating mirror were obtained when the output pulse duration was ~ 2 ns and the fraction of the total energy contained within an angle of ~ 10- 4 rad was ~ 0.3.

Cerium neodymium oxide solid solution synthesis as a potential analogue for substoichiometric AmO2 for radioisotope power systems

NASA Astrophysics Data System (ADS)

Watkinson, E. J.; Ambrosi, R. M.; Williams, H. R.; Sarsfield, M. J.; Stephenson, K.; Weston, D. P.; Marsh, N.; Haidon, C.

2017-04-01

The European Space Agency (ESA) is sponsoring a research programme on the development of americium oxides for radioisotope generators and heater units. Cubic AmO2-(x/2) with an O/Am ratio between 1.65 and 1.75 is a potentially suitable compound for pellet sintering. C-type (Ia-3) Ce1-xNdxO2-(x/2) oxides with 0.5 < x < 0.7 could be used as a surrogate for some Ia-3 AmO2-(x/2). A new Ce1-xNdxO2-(x/2) production process has been investigated where a nominally selected x value of 0.6 was targeted: Ce and Nd nitrates and oxalic acid were added drop-wise into a vessel, where they continuously reacted to create oxalate precipitates. The effect of temperature (25 °C, 60 °C) of the reactants (mixed at 250 revolutions per minute) on oxalate particle shape and size were investigated. Oxalates were calcined at 900 °C to produce oxide particles. Oxalate particle properties were characterised as these are expected to influence oxides particle properties and fuel pellet sintering.

Robustness of fossil fish teeth for seawater neodymium isotope reconstructions under variable redox conditions in an ancient shallow marine setting

NASA Astrophysics Data System (ADS)

Huck, Claire E.; van de Flierdt, Tina; Jiménez-Espejo, Francisco J.; Bohaty, Steven M.; Röhl, Ursula; Hammond, Samantha J.

2016-03-01

Fossil fish teeth from pelagic open ocean settings are considered a robust archive for preserving the neodymium (Nd) isotopic composition of ancient seawater. However, using fossil fish teeth as an archive to reconstruct seawater Nd isotopic compositions in different sedimentary redox environments and in terrigenous-dominated, shallow marine settings is less proven. To address these uncertainties, fish tooth and sediment samples from a middle Eocene section deposited proximal to the East Antarctic margin at Integrated Ocean Drilling Program Site U1356 were analyzed for major and trace element geochemistry, and Nd isotopes. Major and trace element analyses of the sediments reveal changing redox conditions throughout deposition in a shallow marine environment. However, variations in the Nd isotopic composition and rare earth element (REE) patterns of the associated fish teeth do not correspond to redox changes in the sediments. REE patterns in fish teeth at Site U1356 carry a typical mid-REE-enriched signature. However, a consistently positive Ce anomaly marks a deviation from a pure authigenic origin of REEs to the fish tooth. Neodymium isotopic compositions of cleaned and uncleaned fish teeth fall between modern seawater and local sediments and hence could be authigenic in nature, but could also be influenced by sedimentary fluxes. We conclude that the fossil fish tooth Nd isotope proxy is not sensitive to moderate changes in pore water oxygenation. However, combined studies on sediments, pore waters, fish teeth, and seawater are needed to fully understand processes driving the reconstructed signature from shallow marine sections in proximity to continental sources.

Solid State Research, 1973:2.

DTIC Science & Technology

MERCURY COMPOUNDS, CADMIUM COMPOUNDS, TELLURIDES, NEODYMIUM COMPOUNDS, PHOSPHATES , ELECTRON TRANSITIONS, INFRARED OPTICAL MATERIALS, CRYSTAL GROWTH, MAGNESIUM OXIDES, PHOSPHORESCENT MATERIALS, SEMICONDUCTOR DIODES, MICROELECTRONICS

Laser treatment of a neodymium magnet and analysis of surface characteristics

NASA Astrophysics Data System (ADS)

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

2016-08-01

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

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

USGS Publications Warehouse

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

1989-01-01

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

Preparation and characterization of polystyrene/neodymium hydroxide (PS/Nd(OH)3) nano-composites

NASA Astrophysics Data System (ADS)

Alsewailem, Fares D.; Bagabas, Abdulaziz A.; Binkhodor, Yazeed A.

2018-03-01

Composites of polystyrene and Neodymium hydroxide nanrods (PS/Nd(OH)3) were formulated and characterized in this study. Cetyl (1-hexadccyl) trimethyl ammonium bromide (CTAB) was used as dispersion agent for the Nd(OH)3 rods in the PS matrix. PS/Nd(OH)3 composites were prepared by solution and melt compounding. Morphological, thermal, and mechanical properties of the prepared composites were investigated. CTAB was found to be more effective as dispersion agent in composites prepared by solution compounding in comparison with those prepared by melt compounding, and that was due to the mild conditions used in solution compounding. Nonetheless, impact strength of the composite at 0.5 wt% Nd(OH)3 was drastically reduced in the absence of CTAB. Both tensile and impact strengths were found to greatly decreased at higher loading of Nd(OH)3, e.g. 5 wt%, even with the use of CTAB. Thermal stability of the PS/Nd(OH)3 composites was noticeably increased at relatively low loading of Nd(OH)3, e.g. 0.5 wt%.

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

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

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

We have constructed a double clad neodymium doped fiber laser operating on the three-level 4F 3/2 → 4I 9/2 transition. The laser has produced 11.5 W at 925 nm with 55% slope efficiency when pumped at 808 nm, comparable to the best previous results for a double-clad fiber configuration on this transition. Higher power pumping with both 808 nm and 880 nm sources resulted in an output of 27 W, albeit at lower slope efficiency. In both cases, output power was limited by available pump, indicating the potential for further power scaling. To suppress the stronger four-level 4F 3/2 →more » 4I 11/2 transition we developed a waveguide that provides spectral filtering distributed along the length of the fiber, based on an all-solid micro-structured optical fiber design, with resonant inclusions creating a leakage path to the cladding. Furthermore, the waveguide supports large mode areas and provides strong suppression at selectable wavelength bands, thus easing the restrictions on core and cladding sizes that limited power scaling of previous approaches.« less

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

DOE PAGES

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

2016-12-12

We have constructed a double clad neodymium doped fiber laser operating on the three-level 4F 3/2 → 4I 9/2 transition. The laser has produced 11.5 W at 925 nm with 55% slope efficiency when pumped at 808 nm, comparable to the best previous results for a double-clad fiber configuration on this transition. Higher power pumping with both 808 nm and 880 nm sources resulted in an output of 27 W, albeit at lower slope efficiency. In both cases, output power was limited by available pump, indicating the potential for further power scaling. To suppress the stronger four-level 4F 3/2 →more » 4I 11/2 transition we developed a waveguide that provides spectral filtering distributed along the length of the fiber, based on an all-solid micro-structured optical fiber design, with resonant inclusions creating a leakage path to the cladding. Furthermore, the waveguide supports large mode areas and provides strong suppression at selectable wavelength bands, thus easing the restrictions on core and cladding sizes that limited power scaling of previous approaches.« less

Power Systems and Energy Storage Modeling for Directed Energy Weapons

DTIC Science & Technology

2014-06-01

neodymium or ytterbium doped yttrium aluminum garnet (YAG) crystal.6 The Maritime Laser Demonstration (MLD) features several 15 kW slab lasers combined...The laser substrate is similar to a fiber optic cable that is doped with a rare earth element (typically neodymium or ytterbium); many fibers can be...but with different elements. A typical construction consists of a sheet of Lithium- cobalt -oxide and a sheet of carbon separated by an insulator

The neodymium stable isotope composition of the silicate Earth and chondrites

NASA Astrophysics Data System (ADS)

McCoy-West, Alex J.; Millet, Marc-Alban; Burton, Kevin W.

2017-12-01

The non-chondritic neodymium (Nd) 142Nd/144Nd ratio of the silicate Earth potentially provides a key constraint on the accretion and early evolution of the Earth. Yet, it is debated whether this offset is due to the Earth being formed from material enriched in s-process Nd isotopes or results from an early differentiation process such as the segregation of a late sulfide matte during core formation, collisional erosion or a some combination of these processes. Neodymium stable isotopes are potentially sensitive to early sulfide segregation into Earth's core, a process that cannot be resolved using their radiogenic counterparts. This study presents the first comprehensive Nd stable isotope data for chondritic meteorites and terrestrial rocks. Stable Nd measurements were made using a double spike technique coupled with thermal ionisation mass spectrometry. All three of the major classes of chondritic meteorites, carbonaceous, enstatite and ordinary chondrites have broadly similar isotopic compositions allowing calculation of a chondritic mean of δ146/144Nd = -0.025 ± 0.025‰ (±2 s.d.; n = 39). Enstatite chondrites yield the most uniform stable isotope composition (Δ146/144Nd = 26 ppm), with considerably more variability observed within ordinary (Δ146/144Nd = 72 ppm) and carbonaceous meteorites (Δ146/144Nd = 143 ppm). Terrestrial weathering, nucleosynthetic variations and parent body thermal metamorphism appear to have little measurable effect on δ146/144Nd in chondrites. The small variations observed between ordinary chondrite groups most likely reflect inherited compositional differences between parent bodies, with the larger variations observed in carbonaceous chondrites being linked to varying modal proportions of calcium-aluminium rich inclusions. The terrestrial samples analysed here include rocks ranging from basaltic to rhyolitic in composition, MORB glasses and residual mantle lithologies. All of these terrestrial rocks possess a broadly similar Nd

Multiple Doped Erbium Glasses,

DTIC Science & Technology

GLASS, LASERS, ERBIUM, ERBIUM COMPOUNDS, DOPING, OXIDES, OPTIMIZATION, ATOMIC ENERGY LEVELS, PHOSPHATES , YTTERBIUM COMPOUNDS, NEODYMIUM COMPOUNDS, OPTICAL PUMPING, FLUORESCENCE, LIFE EXPECTANCY(SERVICE LIFE), BAND SPECTRA.

Absorption spectra of 4f electron transitions of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid and diethylamine systems and its analytical application

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

Wang Naixing; Qi Ping

1992-06-01

In this paper the absorption spectra of 4f electron transitions of the systems of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid and diethylamine have been studied by normal and third-derivative spectrophotometry. Their molar absorptivities are 80 1.mol{sup {minus}1}.cm{sup {minus}1} for neodymium and 65 1.mol{sup {minus}1}.cm{sup {minus}1} for erbium. Use of the third-derivative spectra, eliminates the interference by other rare earths and increases the sensitivity for Nd and Er. The derivative molar absorptivities are 390 1.mol{sup {minus}1}.cm{sup {minus}1} for Nd and 367 1.mol{sup {minus}1}.cm{sup {minus}1} for Er. The calibration graphs were linear up to 11.8 {mu}g/ml of Nd and 12.3 {mu}g/ml ofmore » Er, respectively. The relative standard deviations evaluated from eleven independent determinations of 7.2 {mu}g/ml (for Nd) and 8.3 {mu}g/ml (for Er) are 1.3% and 1.4%, respectively. The detection limits are 0.2 {mu}g/ml for Nd and 0.3 {mu}g/ml for Er. The method has been developed for determining those two elements in mixture of lanthanides by means of the third-derivative spectra and the analytical results obtained are satisfactory.« less

Rare earth elements and neodymium isotopes in sedimentary organic matter

NASA Astrophysics Data System (ADS)

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

2014-09-01

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

Application of neodymium isotope ratio measurements for the origin assessment of uranium ore concentrates.

PubMed

Krajkó, Judit; Varga, Zsolt; Yalcintas, Ezgi; Wallenius, Maria; Mayer, Klaus

2014-11-01

A novel procedure has been developed for the measurement of (143)Nd/(144)Nd isotope ratio in various uranium-bearing materials, such as uranium ores and ore concentrates (UOC) in order to evaluate the usefulness and applicability of variations of (143)Nd/(144)Nd isotope ratio for provenance assessment in nuclear forensics. Neodymium was separated and pre-concentrated by extraction chromatography and then the isotope ratios were measured by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The method was validated by the measurement of standard reference materials (La Jolla, JB-2 and BCR-2) and the applicability of the procedure was demonstrated by the analysis of uranium samples of world-wide origin. The investigated samples show distinct (143)Nd/(144)Nd ratio depending on the ore type, deposit age and Sm/Nd ratio. Together with other characteristics of the material in question, the Nd isotope ratio is a promising signature for nuclear forensics and suggests being indicative of the source material, the uranium ore. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

High-resolution separation of neodymium and dysprosium ions utilizing extractant-impregnated graft-type particles.

PubMed

Uchiyama, Shoichiro; Sasaki, Takaaki; Ishihara, Ryo; Fujiwara, Kunio; Sugo, Takanobu; Umeno, Daisuke; Saito, Kyoichi

2018-01-19

An efficient method for rare metal recovery from environmental water and urban mines is in high demand. Toward rapid and high-resolution rare metal ion separation, a novel bis(2-ethylhexyl) phosphate (HDEHP)-impregnated graft-type particle as a filler for a chromatography column is proposed. To achieve rapid and high-resolution separation, a convection-flow-aided elution mode is required. The combination of 35 μm non-porous particles and a polymer-brush-rich particle structure minimizes the distance from metal ion binding sites to the convection flow in the column, resulting in minimized diffusional mass transfer resistance and the convection-flow-aided elution mode. The HDEHP-impregnated graft-type non-porous-particle-packed cartridge developed in this study exhibited a higher separation performance for model rare metals, neodymium (III) and dysprosium (III) ions, and a narrower peak at a higher linear velocity, than those of previous HDEHP-impregnated fiber-packed and commercially available Lewatit ® VP OC 1026-packed cartridges. Copyright © 2017 Elsevier B.V. All rights reserved.

Coated conductors

DOEpatents

Arendt, Paul N.; Foltyn, Stephen R.; Stan, Liliana; Usov, Igor O.; Wang, Haiyan

2010-06-15

Articles are provided including a base substrate having a layer of an IBAD oriented material thereon, and, a layer of barium-containing material selected from the group consisting of barium zirconate, barium hafnate, barium titanate, barium strontium titanate, barium dysprosium zirconate, barium neodymium zirconate and barium samarium zirconate, or a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates upon the layer of an IBAD oriented material. Such articles can further include thin films of high temperature superconductive oxides such as YBCO upon the layer of barium-containing material selected from the group consisting of barium zirconate, barium hafnate, barium titanate, barium strontium titanate, barium dysprosium zirconate, barium neodymium zirconate and barium samarium zirconate, or a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates.

Recent Progress in the Development of Neodymium Doped Ceramic Yttria

NASA Technical Reports Server (NTRS)

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

2007-01-01

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

Deglacial Neodymium Isotopic Ratios in the Florida Straits and the Response of Intermediate Waters to Reduced Meridional Overturning Circulation

NASA Astrophysics Data System (ADS)

Marcantonio, F.; Schmidt, M. W.; Franklin, A.; Lynch-Stieglitz, J. M.

2009-12-01

Neodymium behaves quasi-conservatively in seawater, and its isotopic signature can be used as a tracer for oceanic water masses. By analyzing Nd in the authigenic ferromanganese oxide component of marine sediments, past changes in water mass movements have been hypothesized. In the Atlantic Ocean, Nd isotope analysis has been used to trace the variable strength of the meridional overturning circulation (MOC) during the last deglaciation (e.g., Pahnke et al., 2008). Here, we use Nd isotopes to investigate whether a decrease in the strength of the past MOC manifests itself as a reduction (Came et al., 2008) or an increase (Pahnke et al., 2008) in the northward incursion of Antarctic Intermediate Water (AAIW) into the North Atlantic. Sediments from two core sites currently bathed by AAIW within the Florida Straits (546 m and 751 m water depth) are well suited for profiling authigenic Nd isotope ratios. Because the Florida Current represents a major pathway of the Atlantic MOC surface return flow, the Florida Strait sites can shed light on how variations in AAIW are related to changes in Atlantic MOC strength. The sediments range in age from 0 to 25 kyr, and the high sedimentation rates (8 - 200 cm/kyr) ensure that millennial climate events during the deglaciation are captured. The range in ɛNd measured in the shallower core thus far is low (~ 1.5 epsilon units), but significant. There is a trend in the data which suggests more unradiogenic values during the Younger Dryas event when Atlantic MOC slowed down. Such a trend supports the idea based on benthic foraminiferal Cd/Ca data (Came et al., 2008) that, during the Younger Dryas, there was a reduction within the Florida Current of the flow of intermediate, southern-sourced waters. Came et al., 2008, Paleoceanography 23, PA1217. Pahnke et al., 2008, Nature Geoscience 1, 870-874.

Coherent response of Antarctic Intermediate Water and Atlantic Meridional Overturning Circulation during the last deglaciation: reconciling contrasting neodymium isotope reconstructions in tropical Atlantic

NASA Astrophysics Data System (ADS)

Gu, S.; Liu, Z.; Zhang, J.; Rempfer, J.; Joos, F.; Oppo, D.

2017-12-01

Antarctic Intermediate Water (AAIW) plays important roles in the global climate system and the global ocean nutrient and carbon cycles. However, it is unclear how AAIW responds to global climate changes. In particular, neodymium isotopic composition (ɛNd) reconstructions from different locations in tropical Atlantic, have led to a debate on the relationship between the northward penetration of AAIW into the tropical Atlantic and Atlantic Meridional Overturning Circulation (AMOC) variability during the last deglaciation. We resolve this controversy by studying the transient oceanic evolution during the last deglaciation using a neodymium-enabled ocean model. Our results suggest a coherent response of AAIW and AMOC: when AMOC weakens, the northward penetration and transport of AAIW decreases while its depth and thickness increase. Our study highlights that as part of the return flow of the North Atlantic Deep Water (NADW), the northward penetration of AAIW in Atlantic is determined predominately by AMOC intensity. Moreover, the inconsistency among different tropical Atlantic ɛNd reconstructions is reconciled by considering their corresponding core locations and depths, which were influenced by different water masses and ocean currents in the past. The very radiogenic water from the bottom of the Gulf of Mexico and Caribbean Sea, which was previously overlooked in interpretations of deglacial ɛNd variability, can be transported to shallow layers during active AMOC, and modulates ɛNd in the tropical Atlantic. Changes in the AAIW core depth must also be considered. Thus, interpretation of ɛNd reconstructions from the tropical Atlantic is more complicated than suggested in previous studies. ­­

Value analysis of neodymium content in shredder feed: toward enabling the feasibility of rare earth magnet recycling.

PubMed

Bandara, H M Dhammika; Darcy, Julia W; Apelian, Diran; Emmert, Marion H

2014-06-17

In order to facilitate the development of recycling technologies for rare earth magnets from postconsumer products, we present herein an analysis of the neodymium (Nd) content in shredder scrap. This waste stream has been chosen on the basis of current business practices for the recycling of steel, aluminum, and copper from cars and household appliances, which contain significant amounts of rare earth magnets. Using approximations based on literature data, we have calculated the average Nd content in the ferrous shredder product stream to be between 0.13 and 0.29 kg per ton of ferrous scrap. A value analysis considering rare earth metal prices between 2002 and 2013 provides values between $1.32 and $145 per ton of ferrous scrap for this material, if recoverable as pure Nd metal. Furthermore, we present an analysis of the content and value of other rare earths (Pr, Dy, Tb).

Optical radiation hazards of laser welding processes. Part 1: Neodymium-YAG laser.

PubMed

Rockwell, R J; Moss, C E

1983-08-01

High power laser devices are being used for numerous metalworking processes such as welding, cutting and heat treating. Such laser devices are totally enclosed either by the manufacturer or the end-user. When this is done, the total laser system is usually certified by the manufacturer following the federal requirements of the Code of Federal Regulations (CFR) 1040.10 and 10.40.11 as a Class I laser system. Similarly, the end-user may also reclassify an enclosed high-power laser into the Class I category following the requirements of the American National Standards Institute (ANSI) Z-136.1 (1980) standard. There are, however, numerous industrial laser applications where Class IV systems are required to be used in an unenclosed manner. In such applications, there is concern for both ocular and skin hazards caused by direct and scattered laser radiation, as well as potential hazards caused by the optical radiation created by the laser beam's interaction with the metal (i.e. the plume radiation). Radiant energy measurements are reported for both the scattered laser radiation and the resultant plume radiations which were produced during typical unenclosed Class IV Neodymium-YAG laser welding processes. Evaluation of the plume radiation was done with both radiometric and spectroradiometric measurement equipment. The data obtained were compared to applicable safety standards.

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

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

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

2016-01-27

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

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

PubMed

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

2016-02-15

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

A randomized controlled trial of peeling and aspiration of Elschnig pearls and neodymium: yttrium-aluminium-garnet laser capsulotomy.

PubMed

Bhargava, Rahul; Kumar, Prachi; Sharma, Shiv Kumar; Kaur, Avinash

2015-01-01

To compare surgical peeling and aspiration and neodymium yttrium garnet laser capsulotomy for pearl form of posterior capsule opacification (PCO). A prospective, randomized, double blind, study was done at Rotary Eye Hospital, Maranda, Palampur, India, Santosh Medical College Hospital, Ghaziabad, India and Laser Eye Clinic, Noida India. Consecutive patients with pearl form of PCO following surgery, phacoemulsification, manual small incision cataract surgery and conventional extracapsular cataract extraction (ECCE) for age related cataract, were randomized to have peeling and aspiration or neodymium yttrium garnet laser capsulotomy. Corrected distance visual acuity (CDVA), intra-operative and post-operative complications were compared. A total of 634 patients participated in the study, and 314 (49.5%) patients were randomized to surgical peeling and aspiration group and 320 (50.5%) to the Nd:YAG laser group. The mean pre-procedural logMAR CDVA in peeling and neodymium: yttrium-aluminium-garnet (Nd:YAG) laser group was 0.80±0.25 and 0.86±0.22, respectively. The mean final CDVA in peeling group (0.22±0.23) was comparable to Nd:YAG group (0.24±0.28; t test, P=0.240). There was a significant improvement in vision after both the procedures (P<0.001). A slightly higher percentage of patients in Nd:YAG laser group (283/88.3%) than in peeling group (262/83.4%) had a CDVA of 0.5 (20/63) or better at 9mo (P<0.001). On the contrary, patients having CDVA worse than 1.00 (20/200) was also significantly higher in Nd:YAG laser group as compared to peeling group (25/7.7% vs 15/4.7%, respectively). On application of ANCOVA, there was less than 0.001% risk that PCO thickness and total laser energy had no effect on rate of complications in Nd:YAG laser group and less than 0.001 % risk that PCO thickness had no effect on complications in peeling group respectively. Sum of square analysis suggests that in the Nd:YAG laser group, thick PCO had a stronger impact on complications

A randomized controlled trial of peeling and aspiration of Elschnig pearls and neodymium: yttrium-aluminium-garnet laser capsulotomy

PubMed Central

Bhargava, Rahul; Kumar, Prachi; Sharma, Shiv Kumar; Kaur, Avinash

2015-01-01

AIM To compare surgical peeling and aspiration and neodymium yttrium garnet laser capsulotomy for pearl form of posterior capsule opacification (PCO). METHODS A prospective, randomized, double blind, study was done at Rotary Eye Hospital, Maranda, Palampur, India, Santosh Medical College Hospital, Ghaziabad, India and Laser Eye Clinic, Noida India. Consecutive patients with pearl form of PCO following surgery, phacoemulsification, manual small incision cataract surgery and conventional extracapsular cataract extraction (ECCE) for age related cataract, were randomized to have peeling and aspiration or neodymium yttrium garnet laser capsulotomy. Corrected distance visual acuity (CDVA), intra-operative and post-operative complications were compared. RESULTS A total of 634 patients participated in the study, and 314 (49.5%) patients were randomized to surgical peeling and aspiration group and 320 (50.5%) to the Nd:YAG laser group. The mean pre-procedural logMAR CDVA in peeling and neodymium: yttrium-aluminium-garnet (Nd:YAG) laser group was 0.80±0.25 and 0.86±0.22, respectively. The mean final CDVA in peeling group (0.22±0.23) was comparable to Nd:YAG group (0.24±0.28; t test, P=0.240). There was a significant improvement in vision after both the procedures (P<0.001). A slightly higher percentage of patients in Nd:YAG laser group (283/88.3%) than in peeling group (262/83.4%) had a CDVA of 0.5 (20/63) or better at 9mo (P<0.001). On the contrary, patients having CDVA worse than 1.00 (20/200) was also significantly higher in Nd:YAG laser group as compared to peeling group (25/7.7% vs 15/4.7%, respectively). On application of ANCOVA, there was less than 0.001% risk that PCO thickness and total laser energy had no effect on rate of complications in Nd:YAG laser group and less than 0.001 % risk that PCO thickness had no effect on complications in peeling group respectively. Sum of square analysis suggests that in the Nd:YAG laser group, thick PCO had a stronger impact on

Cumulative probability of neodymium: YAG laser posterior capsulotomy after phacoemulsification.

PubMed

Ando, Hiroshi; Ando, Nobuyo; Oshika, Tetsuro

2003-11-01

To retrospectively analyze the cumulative probability of neodymium:YAG (Nd:YAG) laser posterior capsulotomy after phacoemulsification and to evaluate the risk factors. Ando Eye Clinic, Kanagawa, Japan. In 3997 eyes that had phacoemulsification with an intact continuous curvilinear capsulorhexis, the cumulative probability of posterior capsulotomy was computed by Kaplan-Meier survival analysis and risk factors were analyzed using the Cox proportional hazards regression model. The variables tested were sex; age; type of cataract; preoperative best corrected visual acuity (BCVA); presence of diabetes mellitus, diabetic retinopathy, or retinitis pigmentosa; type of intraocular lens (IOL); and the year the operation was performed. The IOLs were categorized as 3-piece poly(methyl methacrylate) (PMMA), 1-piece PMMA, 3-piece silicone, and acrylic foldable. The cumulative probability of capsulotomy after cataract surgery was 1.95%, 18.50%, and 32.70% at 1, 3, and 5 years, respectively. Positive risk factors included a better preoperative BCVA (P =.0005; risk ratio [RR], 1.7; 95% confidence interval [CI], 1.3-2.5) and the presence of retinitis pigmentosa (P<.0001; RR, 6.6; 95% CI, 3.7-11.6). Women had a significantly greater probability of Nd:YAG laser posterior capsulotomy (P =.016; RR, 1.4; 95% CI, 1.1-1.8). The type of IOL was significantly related to the probability of Nd:YAG laser capsulotomy, with the foldable acrylic IOL having a significantly lower probability of capsulotomy. The 1-piece PMMA IOL had a significantly higher risk than 3-piece PMMA and 3-piece silicone IOLs. The probability of Nd:YAG laser capsulotomy was higher in women, in eyes with a better preoperative BCVA, and in patients with retinitis pigmentosa. The foldable acrylic IOL had a significantly lower probability of capsulotomy.

Cataracts induced by neodymium-yttrium-aluminium-garnet laser lysis of vitreous floaters.

PubMed

Koo, Ellen H; Haddock, Luis J; Bhardwaj, Namita; Fortun, Jorge A

2017-06-01

Neodymium-yttrium-aluminium-garnet (Nd:YAG) laser vitreolysis has been proposed as a treatment modality for symptomatic vitreous floaters. The purpose of this paper is to report two cases of cataracts associated with posterior capsular compromise, induced by Nd:YAG laser vitreolysis for symptomatic vitreous floaters. Case series. Two patients who underwent ND:YAG laser vitreolysis for symptomatic floaters, presented with decline in visual acuity in the treated eye after the laser procedure. At the slit-lamp biomicroscope, each patient was found to have a posterior subcapsular cataract in the treated eye, with obvious loss of integrity of the posterior capsule. These two patients underwent cataract extraction by the same surgeon via phacoemulsification. Both eyes were found to have a defect in the posterior capsule intraoperatively. In both cases, a three-piece acrylic intraocular lens implant was placed in the sulcus, achieving optic capture. The best-corrected visual acuity (BCVA) was 20/20 in both patients, at 1 month following the surgery. At 2 months, one patient had a BCVA of 20/15. The second patient maintained a BCVA of 20/20 at 3 months. Secondary cataract formation accompanied by loss of integrity of the posterior capsule is a potential complication of Nd:YAG laser vitreolysis for symptomatic floaters. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

[Two-photon up-conversion fluorescence of a neodymium organic framework Nd(BTC)].

PubMed

Xu, Hui; Jin, Run-zhi; Wu, Chun-yang; Yang, Yu; Qian, Guo-dong

2008-08-01

In the present work, a neodymium organic framework Nd(BTC) was synthesized by the solvothermal reaction of Nd(NO3)3 x 5H2O and H3BTC (BTC = 1,3,5-benzenetricarboxylate) in mixed solvents of DMF, ethanol and water, and was identified by elemental analysis. This MOF complex was characterized using X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TGA-DSC) analysis, UV-visible absorption spectra and fluorescence spectra. This polycrystalline powder lost DMF and H2O when heated to 120 degrees C, then remained stable till the temperature reached 500 degrees C. Near infrared fluorescence at 1064 nm due to the 4 F3/2--> 4 I11/2 transition of Nd3+ ions was exhibited when excited by 808 nm laser beam. It was also been found that up-conversion fluorescence of Nd(BTC) peaked at about 450 nm due to 2 D5/2 -->4 I11/2 transition of Nd3+ ions can be observed under the excitation of a 580 nm laser line. The mechanism of the up-conversion fluorescence of Nd(BTC) at around 450 nm under the excitation of 580 nm laser can be ascribed to both excited-state absorption and energy transfer up-conversion. This result indicated that such MOF can be employed as an up-conversion luminescence material in many potential application areas such as bio-labeling and fluorescence image.

Neodymium isotope evolution of NW Tethyan upper ocean waters throughout the Cretaceous

NASA Astrophysics Data System (ADS)

Pucéat, Emmanuelle; Lécuyer, Christophe; Reisberg, Laurie

2005-08-01

Neodymium isotope compositions of twenty-four fish teeth, nineteen from the NW Tethys and five from different locations within the Tethys, are interpreted to reflect the evolution of Tethyan upper ocean water composition during the Cretaceous and used to track changes in erosional inputs to the NW Tethys and in oceanic circulation throughout the Cretaceous. The rather high ɛNd (up to - 7.6) of the NW Tethyan upper ocean waters recorded from the Late Berriasian to the Early Aptian and the absence of negative excursions during this interval support the presence of a permanent westward flowing Tethys Circumglobal Current (TCC). This implies that temperature variations during this time period, inferred from the oxygen isotope analysis of fish tooth enamel, were not driven by changes in surface oceanic currents, but rather by global climatic changes. The results presented here represent a significant advance over previously published Cretaceous seawater Nd isotope records. Our newly acquired data now allow the identification of two stages of low ɛNd values in the NW Tethys, during the Early Albian-Middle Albian interval (down to - 10) and the Santonian-Early Campanian (down to - 11.4), which alternate with two stages of higher ɛNd values (up to - 9) during the Late Albian-Turonian interval and the Maastrichtian. Used in conjunction with the oxygen isotope record, the fluctuations of ɛNd values can be related to major climatic, oceanographic, and tectonic events that appeared in the western Tethyan domain.

Effect of Partial Substitution of Neodymium with Praseodymium on the Magnetic and Process Properties of Sintered Magnets of Type NdFeB

NASA Astrophysics Data System (ADS)

Dormidontov, N. A.; Dormidontov, A. G.; Lileev, A. S.; Kamynin, A. V.; Lukin, A. A.

2017-01-01

The effect of substitution of neodymium with praseodymium in sintered magnets of type NdFeB on their magnetic and process properties in the concentration range of [Pr] = 0 - 13 wt.% is studied. The special features of milling of the alloys, sintering processes and heat treatments in the production of magnets containing praseodymium are discussed. Hysteresis characteristics of B r ≥ 1.2 T, H cJ ≥ 1200 kA/m, H cb ≥ 880 kA/m, H k ≥ 960 kA/m, and BH max ≥ 280 kJ/m3 are obtained for magnets with composition (in wt.%) 33 Nd, 10 Pr, 1.5 (Ti + Al + Cu), 1.3 B, the remainder Fe.

Histological Evaluation of Retina after Photo Disruption for Vitreous Humor by Q-Switched Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) Laser

PubMed Central

Kameel Ghaly, Sally; Foad Ghoneim, Dina; Abdelkawi Ahmed, Salwa; Medhat Abdel-Salam, Ahmed

2013-01-01

Introduction: Rabbits’ eyes were exposed to vitreous humor liquefaction with Q - switched (sometimes called “ giant pulses”) Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) laser using two different energy protocols (5 mJ X 100 pulse and 10 mJ X 50 pulse)with and without vitamin C administration. The histological changes in the retina were investigated to evaluate the protective role of vitamin C. Methods: The rabbits were divided into four main groups (n= 12 each). The first group was divided into three subgroups (n=4) and then treated with 5 mJ X 100 pulse (X means times) delivered to the anterior, middle and posterior vitreous humor respectively. The second group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the first group.The third group was divided into three subgroups (n=4) and then treated with 10 mJ X 50 pulse delivered to the anterior, middle and posterior vitreous respectively. The fourth group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the third group. After two weeks, rabbits were decapitated and histological examination for the retina was performed. Results: The results showed that, the anterior vitreous group exposed to 5mJX100 pulse and supplemented with vitamin C, showed no obvious change. Furthermore, all other treated groups showed alteration in retina’s tissues histology after laser. Conclusion: Application of Q-switched Nd: YAG laser in vitreous humor liquefaction induces changes in retina’s layers. Although there were some sorts of improvements in retinas supplemented with vitamin C, it cannot protect them against laser oxidative damage. PMID:25606329

Commentary: Is There Clinical Benefit From Using a Diode or Neodymium:Yttrium-Aluminum-Garnet Laser in the Treatment of Periodontitis?

PubMed

Cobb, Charles M

2016-10-01

Despite a quarter of a century of laser research, there is a persistent debate regarding the efficacy of dental lasers in the treatment of periodontitis or periodontal maintenance therapy. There are many claims and much hyperbole surrounding the use of lasers, either as a monotherapy or adjunctive to scaling and root planing, to treat periodontitis. There is little evidence that using a diode or neodymium:yttrium-aluminum-garnet laser adds clinical value over and above conventional non-surgical or surgical periodontal treatment. There is a significant need for better designed human clinical trials. Data from such trials should be analyzed according to initial probing depth and characteristics of the treated sites, such as non-molar, molar flat surfaces, and molar furcations, and evaluated for long-term post-treatment results.

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

NASA Astrophysics Data System (ADS)

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

2016-04-01

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

Effect of mixing Ce{sup 3+} and Nd{sup 3+} ions in equimolar ratio on structural, optical and dielectric properties on pure cerium orthovanadate and neodymium orthovanadate

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

Verma, Seema; Gupta, Rashmi; Bamzai, K.K., E-mail: kkbamz@yahoo.com

2016-09-15

Highlights: • CeV, NdV and mixed CeNdV nanoparticle prepared by chemical co precipitation method. • With mixing of Ce{sup 3+} and Nd{sup 3+} morphology is totally changed in mixed CeNdV. • Optical band energy of CeV, NdV and CeNdV shows good photocatalyst under UV light. • Conduction mechanism in CeV due to large polaron and small polaron in CeNdV. - Abstract: Cerium orthovanadate, neodymium orthovanadate and mixed cerium neodymium orthovanadate nanoparticles was prepared by co-precipitation method. Powder X-ray diffraction reveals tetragonal zircon structure. Slight increase in lattice parameter, volume and decrease in X-ray density inferred that Ce{sup 3+} and Nd{supmore » 3+} ion replaces each other. Transmission electron microscopy suggests change in morphology with the effect of mixing and validates formation of nanocrystalline material. The infrared transmittance spectrum confirmed the presence of various functional groups. Dielectric properties as function of frequency show dielectric constant and loss tangent decreases with increase in frequency which is due to Maxwell–Wagner type interfacial polarization. The variation of AC conductivity measurement with frequency suggests conduction mechanism due to large polaron hopping in CeV whereas small polaron in mixed CeNdV. The activation energy decreases with rising frequency indicates the conduction mechanism is based on polaron hopping between localized states in disordered manner.« less

Potassium titanyl arsenate based cascaded optical parametric oscillator emit at 2.5 µm derived by neodymium-doped yttrium lithium fluoride laser

NASA Astrophysics Data System (ADS)

Duan, Yanmin; Zhang, Jing; Guo, Junhong; Zhu, Haiyong; Zhang, Yongchang; Xu, Changwen; Wang, Hongyan; Zhang, Yaoju

2018-04-01

We reported a potassium titanyl arsenate (KTA) based cascaded optical parametric oscillator (OPO). The secondary OPO signal light at 2.5 µm was obtained with two OPO processes in one non-critical phase matching cut KTA crystal. This cascaded OPO was driven by a Q-switched neodymium-doped yttrium lithium fluoride (Nd:YLF) laser at 1047 nm. Making full use of the negative thermal lens effect and long upper level fluorescence lifetime of Nd:YLF, signal power of 605 mW at 2503 nm was achieved with a pulse repetition frequency of 15 kHz and an incident diode pump power of 9.7 W. Therefore, the cascaded OPO derived by Q-switched Nd:YLF laser could provide high peak power pulsed laser emission in mid-infrared band.

Neodymium: YAG laser damage threshold. A comparison of injection-molded and lathe-cut polymethylmethacrylate intraocular lenses.

PubMed

Wilson, S E; Brubaker, R F

1987-01-01

The possibility that injection-molded intraocular lenses (IOLs) with imperfections called iridescent clefts could have a decreased threshold to neodymium: YAG (Nd:YAG) laser-induced damage was investigated. Thresholds for Nd:YAG laser-induced damage were determined for injection-molded and lathe-cut polymethylmethacrylate lenses. When aimed at a membrane in contact with a posterior convex surface, the average thresholds were 0.96 +/- 0.18 mJ (Standard deviation [SD]) and 1.80 +/- 0.55 mJ, respectively. The difference was significant at P = 0.001. When injection-molding polymethylmethacrylate was used to make lathe-cut IOLs, very few iridescent clefts were present, and the threshold to Nd:YAG laser-induced damage was 0.94 +/- 0.25 mJ. Iridescent clefts are therefore produced during the injection-molding process but they do not lower the threshold to Nd:YAG laser-induced damage. Rather, the reduced threshold in injection-molded lenses is most probably a result of the polymethylmethacrylate used in their manufacture. Clinically, iridescent clefts in a lens suggest that it has been manufactured by an injection-molding process and that Nd:YAG laser posterior capsulotomy must be performed at the lowest possible energy level to avoid damage.

Interactions of praseodymium and neodymium with nucleosides and nucleotides: absorption difference and comparative absorption spectral study.

PubMed

Misra, S N; Anjaiah, K; Joseph, G; Abdi, S H

1992-02-01

The interactions of praseodymium(III) and neodymium(III) with nucleosides and nucleotides have been studied in different stoichiometry in water and water-DMF mixtures by employing absorption difference and comparative absorption spectrophotometry. The 4f-4f bands were analysed by linear curve analysis followed by gaussian curve analysis, and various spectral parameters were computed, using partial and multiple regression method. The magnitude of changes in both energy interaction and intensity were used to explore the degree of outer and inner sphere coordination, incidence of covalency and the extent of metal 4f-orbital involvement in chemical bonding. Crystalline complexes of the type [Ln(nucleotide)2(H2O)2]- (where nucleotide--GMP or IMP) were characterized by IR, 1H NMR, 31P NMR data. These studies indicated that the binding of the nucleotide is through phosphate oxygen in a bidentate manner and the complexes undergo substantial ionisation in aqueous medium, thereby supporting the observed weak 4f-4f bands and lower values for nephelauxetic effect (1-beta), bonding (b) and covalency (delta) parameters derived from coulombic and spin orbit interaction parameters.

Optical and spectroscopic properties of neodymium doped cadmium-sodium borate glasses

NASA Astrophysics Data System (ADS)

Mohan, Shaweta; Thind, Kulwant Singh

2017-10-01

Neodymium doped cadmium sodium borate glasses having composition xCdO-(40-x) Na2CO3-59.5H3BO3-0.5Nd2O3; x = 10, 20 and 30 mol% were prepared by conventional melt-quenching technique. X-ray diffraction studies confirmed the amorphous nature of the prepared glasses. Conventional methods were used to determine the physical properties such as density, molar volume, refractive index, and rare earth ion concentration. The Judd-Ofelt theory was applied on the optical absorption spectra of the glasses to evaluate the three phenomenological intensity parameters Ω2, Ω4 and Ω6. The calculated intensity parameters were further used to predict the radiative transition probability (A), radiative lifetime (τR) and branching ratio (βR) for the various fluorescent levels of Nd3+ ion in the prepared glass series. The effect of the compositional changes on the spectroscopic characteristics of Nd3+ ions have been studied and reported. The value of Ω2 is found to decrease with the decrease in the sodium content and the corresponding increase in the cadmium content. This can be ascribed to the changes in the asymmetry of the ligand field at the rare earth ion site and the change in rare earth oxygen (RE-O) covalency. Florescence spectra has been used to determine the peak wavelength (λp), effective line widths (Δλeff) and stimulated emission cross-section (σp) for the 4F3/2 → 4I9/2,4I11/2,4I13/2 transitions of the Nd3+ ion. The reasonably higher values of branching ratios and stimulated emission cross-section for the prepared glasses points towards the efficacy of these glasses as laser host materials. However, the glass with more sodium content is found to show better lasing properties.

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

PubMed

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

2015-01-01

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

Dynamic photopatterning of cells in situ by Q-switched neodymium-doped yttrium ortho-vanadate laser.

PubMed

Deka, Gitanjal; Okano, Kazunori; Kao, Fu-Jen

2014-01-01

Cellular micropattering has been increasingly adopted in quantitative biological experiments. A Q-switched pulsed neodymium-doped yttrium ortho-vanadate (Nd∶YVO4) laser directed in-situ microfabrication technique for cell patterning is presented. A platform is designed uniquely to achieve laser ablation. The platform is comprised of thin gold coating over a glass surface that functions as a thermal transducer and is over-layered by a cell repellant polymer layer. Micropatterns are engraved on the platform, subsequently exposing specific cell adhesive micro-domains by ablating the gold-polymer coating photothermally. Experimental results indicate that the proposed approach is applicable under culture conditions, viable toward cells, and has a higher engraving speed. Possible uses in arraying isolated single cells on the platform are also shown. Additionally, based on those micro-patterns, dynamic cellular morphological changes and migrational speed in response to geometrical barriers are studied to demonstrate the potential applications of the proposed approach. Our results further demonstrate that cells in narrower geometry had elongated shapes and higher migrational speed than those in wider geometry. Importantly, the proposed approach will provide a valuable reference for efforts to study single cell dynamics and cellular migration related processes for areas such as cell division, wound healing, and cancer invasion.

Metal-organic chemical vapor deposition of cerium oxide, gallium-indium-oxide, and magnesium oxide thin films: Precursor design, film growth, and film characterization

NASA Astrophysics Data System (ADS)

Edleman, Nikki Lynn

A new class of volatile, low-melting, fluorine-free lanthanide metal-organic chemical vapor deposition (MOCVD) precursors has been developed. The neutral, monomeric cerium, neodymium, gadolinium, and erbium complexes are coordinatively saturated by a versatile, multidentate, ether-functionalized beta-ketoiminate ligand, and complex melting point and volatility characteristics can be tuned by altering the alkyl substituents on the ligand periphery. Direct comparison with lanthanide beta-diketonate complexes reveals that the present precursor class is a superior choice for lanthanide oxide MOCVD. Epitaxial CeO 2 buffer layer films have been grown on (001) YSZ substrates by MOCVD at significantly lower temperatures than previously reported using one of the newly developed cerium precursors. High-quality YBCO films grown on these CeO2 buffer layers by POMBE exhibit very good electrical transport properties. The cerium complex has therefore been explicitly demonstrated to be a stable and volatile precursor and is attractive for low-temperature growth of coated conductor multilayer structures by MOCVD. Gallium-indium-oxide thin films (GaxIn2-xO 3), x = 0.0˜1.1, have been grown by MOCVD using the volatile metal-organic precursors In(dpm)3 and Ga(dpm)3. The films have a homogeneously Ga-substituted, cubic In2O3 microstructure randomly oriented on quartz or heteroepitaxial on (100) YSZ single-crystal substrates. The highest conductivity of the as-grown films is found at x = 0.12. The optical transmission window and absolute transparency of the films rivals or exceeds that of the most transparent conductive oxides known. Reductive annealing results in improved charge transport characteristics with little loss of optical transparency. No significant difference in electrical properties is observed between randomly oriented and heteroepitaxial films, thus arguing that carrier scattering effects at high-angle grain boundaries play a minor role in the film conductivity mechanism

Tungsten Bronze Barium Neodymium Titanate (Ba(6-3n)Nd(8+2n)Ti(18)O(54)): An Intrinsic Nanostructured Material and Its Defect Distribution.

PubMed

Azough, Feridoon; Cernik, Robert Joseph; Schaffer, Bernhard; Kepaptsoglou, Demie; Ramasse, Quentin Mathieu; Bigatti, Marco; Ali, Amir; MacLaren, Ian; Barthel, Juri; Molinari, Marco; Baran, Jakub Dominik; Parker, Stephen Charles; Freer, Robert

2016-04-04

We investigated the structure of the tungsten bronze barium neodymium titanates Ba(6-3n)Nd(8+2n)Ti(18)O(54), which are exploited as microwave dielectric ceramics. They form a complex nanostructure, which resembles a nanofilm with stacking layers of ∼12 Å thickness. The synthesized samples of Ba(6-3n)Nd(8+2n)Ti(18)O(54) (n = 0, 0.3, 0.4, 0.5) are characterized by pentagonal and tetragonal columns, where the A cations are distributed in three symmetrically inequivalent sites. Synchrotron X-ray diffraction and electron energy loss spectroscopy allowed for quantitative analysis of the site occupancy, which determines the defect distribution. This is corroborated by density functional theory calculations. Pentagonal columns are dominated by Ba, and tetragonal columns are dominated by Nd, although specific Nd sites exhibit significant concentrations of Ba. The data indicated significant elongation of the Ba columns in the pentagonal positions and of the Nd columns in tetragonal positions involving a zigzag arrangement of atoms along the b lattice direction. We found that the preferred Ba substitution occurs at Nd[3]/[4] followed by Nd[2] and Nd[1]/[5] sites, which is significantly different to that proposed in earlier studies. Our results on the Ba(6-3n)Nd(8+2n)Ti(18)O(54) "perovskite" superstructure and its defect distribution are particularly valuable in those applications where the optimization of material properties of oxides is imperative; these include not only microwave ceramics but also thermoelectric materials, where the nanostructure and the distribution of the dopants will reduce the thermal conductivity.

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

NASA Astrophysics Data System (ADS)

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

2017-05-01

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

Deglacial variability of Antarctic Intermediate Water penetration into the North Atlantic from authigenic neodymium isotope ratios

NASA Astrophysics Data System (ADS)

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

2012-09-01

Understanding intermediate water circulation across the last deglacial is critical in assessing the role of oceanic heat transport associated with Atlantic Meridional Overturning Circulation variability across abrupt climate events. However, the links between intermediate water circulation and abrupt climate events such as the Younger Dryas (YD) and Heinrich Event 1 (H1) are still poorly constrained. Here, we reconstruct changes in Antarctic Intermediate Water (AAIW) circulation in the subtropical North Atlantic over the past 25 kyr by measuring authigenic neodymium isotope ratios in sediments from two sites in the Florida Straits. Our authigenic Nd isotope records suggest that there was little to no penetration of AAIW into the subtropical North Atlantic during the YD and H1. Variations in the northward penetration of AAIW into the Florida Straits documented in our authigenic Nd isotope record are synchronous with multiple climatic archives, including the Greenland ice core δ18O record, the Cariaco Basin atmosphere Δ14C reconstruction, the Bermuda Rise sedimentary Pa/Th record, and nutrient and stable isotope data from the tropical North Atlantic. The synchroneity of our Nd records with multiple climatic archives suggests a tight connection between AAIW variability and high-latitude North Atlantic climate change.

Life Cycle Assessment of Neodymium-Iron-Boron Magnet-to-Magnet Recycling for Electric Vehicle Motors.

PubMed

Jin, Hongyue; Afiuny, Peter; Dove, Stephen; Furlan, Gojmir; Zakotnik, Miha; Yih, Yuehwern; Sutherland, John W

2018-03-20

Neodymium-iron-boron (NdFeB) magnets offer the strongest magnetic field per unit volume, and thus, are widely used in clean energy applications such as electric vehicle motors. However, rare earth elements (REEs), which are the key materials for creating NdFeB magnets, have been subject to significant supply uncertainty in the past decade. NdFeB magnet-to-magnet recycling has recently emerged as a promising strategy to mitigate this supply risk. This paper assesses the environmental footprint of NdFeB magnet-to-magnet recycling by directly measuring the environmental inputs and outputs from relevant industries and compares the results with production from "virgin" materials, using life cycle assessments. It was found that magnet-to-magnet recycling lowers environmental impacts by 64-96%, depending on the specific impact categories under investigation. With magnet-to-magnet recycling, key processes that contribute 77-95% of the total impacts were identified to be (1) hydrogen mixing and milling (13-52%), (2) sintering and annealing (6-24%), and (3) electroplating (6-75%). The inputs from industrial sphere that play key roles in creating these impacts were electricity (24-93% of the total impact) and nickel (5-75%) for coating. Therefore, alternative energy sources such as wind and hydroelectric power are suggested to further reduce the overall environmental footprint of NdFeB magnet-to-magnet recycling.

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

PubMed Central

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

2017-01-01

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

Seasonal variations in dissolved neodymium isotope composition in the Bay of Bengal

NASA Astrophysics Data System (ADS)

Yu, Zhaojie; Colin, Christophe; Meynadier, Laure; Douville, Eric; Dapoigny, Arnaud; Reverdin, Gilles; Wu, Qiong; Wan, Shiming; Song, Lina; Xu, Zhaokai; Bassinot, Frank

2017-12-01

Constraining the dissolved neodymium (Nd) cycle in the ocean is paramount for using Nd isotopic composition (εNd) as a tracer to reconstruct deep-sea paleocirculations or continental weathering on different time scales. Dissolved εNd has been measured in seawater samples from six hydrological stations collected along ∼89°E North-South transect in the Bay of Bengal (BoB) in order to assess the impact of seasonal freshwater and sediment discharges from the continental river systems. Seawater samples collected in this study during June 2012 reveal more radiogenic εNd (a difference of ∼2 Epsilon units for the upper 2000 m, and ∼0.5 Epsilon unit below 2000 m) and ∼3-8 pmol/kg lower Nd concentrations than the reported values of nearby seawater samples collected in November 2008. These observations are most plausibly explained by a seasonal variations in dissolved Nd concentrations and εNd in the BoB, induced by seasonal variations in the freshwater and sediment discharges from the Ganges-Brahmaputra (G-B) river system. However, we cannot entirely exclude the possibility of spatial differences given that the water stations collected in this study are not exactly the same positions collected in November 2008. A two-box model suggests, (1) the particulate Nd inputs from the G-B river system mainly control the seasonal shift of εNd observed in the BoB seawater, and (2) a very rapid Nd exchange exists between lithogenic particles and seawater (at least on the scale of a few months). Seasonal changes in seawater εNd may also occur in other marginal seas and in the outflows of major rivers, and these need to be taken into account when using the εNd proxy in the ocean.

3-D laser confocal microscopy study of the oxidation of NdFeB magnets in atmospheric conditions

NASA Astrophysics Data System (ADS)

Meakin, J. P.; Speight, J. D.; Sheridan, R. S.; Bradshaw, A.; Harris, I. R.; Williams, A. J.; Walton, A.

2016-08-01

Neodymium iron boron (NdFeB) magnets are used in a number of important applications, such as generators in gearless wind turbines, motors in electric vehicles and electronic goods (e.g.- computer hard disk drives, HDD). Hydrogen can be used as a processing gas to separate and recycle scrap sintered Nd-Fe-B magnets from end-of-life products to form a powder suitable for recycling. However, the magnets are likely to have been exposed to atmospheric conditions prior to processing, and any oxidation could lead to activation problems for the hydrogen decrepitation reaction. Many previous studies on the oxidation of NdFeB magnets have been performed at elevated temperatures; however, few studies have been formed under atmospheric conditions. In this paper a combination of 3-D laser confocal microscopy and Raman spectroscopy have been used to assess the composition, morphology and rate of oxidation/corrosion on scrap sintered NdFeB magnets. Confocal microscopy has been employed to measure the growth of surface reaction products at room temperature, immediately after exposure to air. The results showed that there was a significant height increase at the triple junctions of the Nd-rich grain boundaries. Using Raman spectroscopy, the product was shown to consist of Nd2O3 and formed only on the Nd-rich triple junctions. The diffusion coefficient of the triple junction reaction product growth at 20 °C was determined to be approximately 4 × 10-13 cm2/sec. This value is several orders of magnitude larger than values derived from the diffusion controlled oxide growth observations at elevated temperatures in the literature. This indicates that the growth of the room temperature oxidation products are likely defect enhanced processes at the NdFeB triple junctions.

Study of boro-tellurite glasses doped with neodymium oxide

NASA Astrophysics Data System (ADS)

Sanjay, Kishore, N.; Sheoran, M. S.; Devi, S.

2018-05-01

Borotellurite glasses doped with Nd2O3 [xB2O3(95-x)TeO25Nd2O3] have been prepared by the standard melt-quenching technique. Amorphous nature of the present system was estimated by XRD patterns. The thermal parameters like glass transition temperature (Tg), crystallization (Tc) and melting (Tm) temperatures have been estimated from differential scanning calorimetry (DSC) traces. Density and molar volume have been determined. It was found that Tg is increased due to increasing number of Te-O bonds were replaced by a number of stronger B-O bonds whereas density was decreased with an increase in B2O3 content is due to the higher degree of cross-bonding between the Boron and non-bridging oxygen ions resulting in a strengthening of glass network.

Laser direct patterning of indium tin oxide for defining a channel of thin film transistor.

PubMed

Wang, Jian-Xun; Kwon, Sang Jik; Han, Jae-Hee; Cho, Eou Sik

2013-11-01

In this work, using a Q-switched diode-pumped neodymium-doped yttrium vanadate (Nd:YVO4, lambda = 1064 nm) laser, a direct patterning of indium tin oxide (ITO) channel was realized on glass substrates and the results were compared and analyzed in terms of the effect of repetition rate, scanning speed on etching characteristics. The results showed that the laser conditions of 40 kHz repetition rate with a scanning speed of 500 mm/s were appropriate for the channeling of ITO electrodes. The length of laser-patterned channel was maintained at about 55 microm. However, residual spikes (about 50 nm in height) of ITO were found to be formed at the edges of the laser ablated area and a few ITO residues remained on the glass substrate after laser scanning. By dipping the laser-ablated ITO film in ITO diluted etchant (ITO etchant/DI water: 1/10) at 50 degrees C for 3 min, the spikes and residual ITO were effectively removed. At last, using the laser direct patterning, a bottom-source-drain indium gallium zinc oxide thin film transistor (IGZO-TFT) was fabricated. It is successfully demonstrated that the laser direct patterning can be utilized instead of photolithography to simplify the fabrication process of TFT channel, resulting in the increase of productivity and reduction of cost.

Fingerprinting Northeast Atlantic water masses using neodymium isotopes

NASA Astrophysics Data System (ADS)

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

2017-08-01

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

Clinical and Histopathologic Assessment of Facial Melasma After Low-Fluence Q-Switched Neodymium-Doped Yttrium Aluminium Garnet Laser.

PubMed

Hofbauer Parra, Camila Anna; Careta, Mariana Figueroa; Valente, Neusa Yuriko Sakai; de Sanches Osório, Nuno Eduardo Guimaraes; Torezan, Luis Antonio Ribeiro

2016-04-01

Melasma is a frequent and difficult to treat skin disorder. Results of laser therapy are inconsistent. To determine the safety and efficacy of low-fluence Q-switched neodymium-doped yttrium aluminum garnet (QS Nd:YAG) laser for melasma treatment and assess recurrence rates and histopathologic findings before and after treatment. Twenty patients were treated with 10 weekly sessions of low-fluence 1064-nm QS Nd:YAG laser at 1-week intervals. The modified Melasma Area and Severity Index (mMASI) score was evaluated at baseline; 1 week; and 1, 3, and 6 months after treatment. Epidermal melanin quantification was performed on 10 biopsy samples and compared before and after treatment. All patients showed improvement by mMASI scores, range (21%-75%) compared with that at baseline. No permanent side effects occurred. The recurrence rate was 81%. By histopathology, a slight, nonsignificant (p = .305) decrease in melanin deposition was seen in all layers of the epidermis 1 week after the laser treatments ended. The results confirm the safety and effectiveness of low-fluence QS Nd:YAG laser for treating melasma; however, the high recurrence suggests poor long-term results when the laser is used as a monotherapy.

The stable and water-soluble neodymium-doped lanthanide fluoride nanoparticles for near infrared probing of copper ion.

PubMed

Xue, Fang-Min; Wang, He-Fang

2012-09-15

Neodymium (Nd(3+)) doped nanomaterials exhibited the unique near infrared (NIR) luminescence properties. However, the application of Nd-doped nanomaterials to chemosensors was rarely explored. Herein, the water-soluble 2-aminoethyl dihydrogen phosphate stabilized Nd-doped LaF(3) (ADP-Nd-LaF(3)) nanoparticles were explored as the NIR probe for chemosensors. The NIR emission intensity at 1061 nm of ADP-Nd-LaF(3) nanoparticles kept stable in the aqueous solution of various pH and coexisting of most common metal ions except copper ion, consequently, the ADP-Nd-LaF(3) nanoparticles were developed as a high selective NIR probe for Cu(II). The NIR emission of ADP-Nd-LaF(3) exhibits a linear quenching response to Cu(II) in the range 5-100 μM, with a detection limit of 0.8 μM. The precision of eleven replicate detections of 5 μM Cu(II) was 0.5% (RSD). The recovery of spiked Cu(II) in human urine and waste water samples ranged from 102 to 109%. The possible mechanism of Cu(II)-induced fluorescence quenching of ADP-Nd-LaF(3) nanoparticles was also discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

Treatment of café-au-lait macules with a high-fluenced 1064-nm Q-switched neodymium:yttrium aluminum garnet laser.

PubMed

Kim, Jiehoon; Hur, Hoon; Kim, Yu Ri; Cho, Sung Bin

2018-02-01

Café-au-lait macules (CALMs) are light to dark brown macules or patches of increased melanin concentration found along the dermoepidermal junction. Although many attempts to treat CALMs using various kinds of laser/light-based devices have been reported, CALMs remain refractory thereto with high recurrence rates. In this case series, we describe four patients with idiopathic CALMs that were effectively and safely treated with a non-ablative, high-fluenced, Q-switched (QS), 1064-nm neodymium:yttrium aluminum garnet (Nd:YAG) laser. The typical laser parameters for treating CALMs, including a spot size of 7-7.5 mm, a fluence of 2.4-2.5 J/cm 2 , and one to two passes until the appearance of mild erythema, but not petechiae, were utilized in this study over 12-24 treatment sessions at 2-week intervals. We suggest that high-fluenced QS 1064-nm Nd:YAG laser treatment can be used as an effective and alternative treatment modality for CALMs with minimal risk of side effects.

Superconducting structure

DOEpatents

Kwon, Chuhee; Jia, Quanxi; Foltyn, Stephen R.

2003-04-01

A superconductive structure including a dielectric oxide substrate, a thin buffer layer of a superconducting material thereon; and, a layer of a rare earth-barium-copper oxide superconducting film thereon the thin layer of yttrium-barium-copper oxide, the rare earth selected from the group consisting of samarium, gadolinium, ytterbium, erbium, neodymium, dysprosium, holmium, lutetium, a combination of more than one element from the rare earth group and a combination of one or more elements from the rare earth group with yttrium, the buffer layer of superconducting material characterized as having chemical and structural compatibility with the dielectric oxide substrate and the rare earth-barium-copper oxide superconducting film is provided.

Superconducting Structure

DOEpatents

Kwon, Chuhee; Jia, Quanxi; Foltyn, Stephen R.

2005-09-13

A superconductive structure including a dielectric oxide substrate, a thin buffer layer of a superconducting material thereon; and, a layer of a rare earth-barium-copper oxide superconducting film thereon the thin layer of yttrium-barium-copper oxide, the rare earth selected from the group consisting of samarium, gadolinium, ytterbium, erbium, neodymium, dysprosium, holmium, lutetium, a combination of more than one element from the rare earth group and a combination of one or more elements from the rare earth group with yttrium, the buffer layer of superconducting material characterized as having chemical and structural compatibility with the dielectric oxide substrate and the rare earth-barium-copper oxide superconducting film is provided.

Solvent Selection for Extraction of Neodymium Concentrates of Monazite Sand Processed Product

NASA Astrophysics Data System (ADS)

Setyadji, Moch; Purwani, MV

2018-02-01

The extraction of neodymium concentrates of monazite sand processed product has been done. The objective of this investigation was to determine the best solvent to separate Nd from Nd concentrate. As an aqueous phase was Nd(OH)3 concentrated in HNO3 and as solvent or the organic phase was trioctylamine (TOA). tryibuthyl phosphate (TBP). trioctylphosphine oxyde (TOPO) and di-ethyl hexyl phosphoric acid (D2EHPA) in kerosene. The investigated variables were HNO3 concentration. feed concentration. solvent concentration or solvent in kerosene. time and stirring speeds. From the investigation on the selection of solvent for the extraction of Nd(OH)3 concentrate with various solvents. it was concluded that the extraction of Nd could be carried out by using TBP or TOA. Extraction of Nd using TOA at the optimum HNO3 concentration of 2M. feed concentration of 5 gram/10 mL. TOA in kerosene concentration of 6 %. stirring time of 15 minutes. stirring speed of 200 rpm was chosen if the Y concentration in Nd concentrate is small. In these condition DNd obtained was 0.65; extraction efficiency of Nd (ENd)=37.10%. the concentrations of Nd2(C2O4)3 = 67.14%. Ce2(C2O4)3 = 1.79%. La2(C2O4)3 = 1.37% and Y2(C2O4)3 = 24.70%. Extraction of Nd using TBP at the optimum HNO3 concentration of 1M. feed concentration of 5 gram/10 m. the TBP concentration in kerosene of 15%. stirring time of 15 minutes and stirring speed of 200 rpm was chosen if the Ce concentration in Nd concentrate is small. In these condition DNd obtained was 0.20. extraction efficiency of Nd (ENd)=17%. concentration of Nd2(C2O4)3 = 70.84%. Ce2(C2O4)3=15.53%. La2(C2O4)3 = 0.00% and Y2(C2O4)3 = 8.63%.

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

NASA Astrophysics Data System (ADS)

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

2016-08-01

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

Photocatalytic Water Splitting for O2 Production under Visible Light Irradiation Using NdVO4-V2O5 Hybrid Powders

PubMed Central

Chiang, Tzu Hsuan; Chen, Tso-Ming

2017-01-01

The study investigated photocatalytic water splitting for O2 production under visible light irradiation using neodymium vanadium oxide (NdVO4) and vanadium oxide (V2O5) hybrid powders. The results in a sacrificial agent of 0.01 M AgNO3 solution were obtained, and the highest photocatalytic O2 evolution was 2.63 μmol/h, when the hybrid powders were prepared by mixing Nd and V at a volume ratio of 1:3 at a calcination temperature of 350 °C for 1 h. The hybrid powders were synthesized by neodymium nitrate and ammonium metavanadate using the glycothermal method in ethylene glycol at 120 °C for 1 h. The hybrid powders consisted of two shapes, NdVO4 nanoparticles and the cylindrical V2O5 particles, and they possessed the ability for photocatalytic oxygen (O2) evolution during irradiation with visible light. The band gaps and structures of the hybrid powders were analyzed using UV-visible spectroscopy and transmission electron microscopy. PMID:28772692

Superconducting composite with multilayer patterns and multiple buffer layers

DOEpatents

Wu, X.D.; Muenchausen, R.E.

1993-10-12

An article of manufacture is described including a substrate, a patterned interlayer of a material selected from the group consisting of magnesium oxide, barium-titanium oxide or barium-zirconium oxide, the patterned interlayer material overcoated with a secondary interlayer material of yttria-stabilized zirconia or magnesium-aluminum oxide, upon the surface of the substrate whereby an intermediate article with an exposed surface of both the overcoated patterned interlayer and the substrate is formed, a coating of a buffer layer selected from the group consisting of cerium oxide, yttrium oxide, curium oxide, dysprosium oxide, erbium oxide, europium oxide, iron oxide, gadolinium oxide, holmium oxide, indium oxide, lanthanum oxide, manganese oxide, lutetium oxide, neodymium oxide, praseodymium oxide, plutonium oxide, samarium oxide, terbium oxide, thallium oxide, thulium oxide, yttrium oxide and ytterbium oxide over the entire exposed surface of the intermediate article, and, a ceramic superconductor. 5 figures.

Picosecond 532-nm neodymium-doped yttrium aluminium garnet laser-a novel and promising modality for the treatment of café-au-lait macules.

PubMed

Artzi, Ofir; Mehrabi, Joseph N; Koren, Amir; Niv, Roni; Lapidoth, Moshe; Levi, Assi

2018-05-01

Café-au-lait macules (CALMs) present as benign hyperpigmented, well-circumscribed spots on the skin for which many patients seek treatment for aesthetic reasons. The objective of this study is to report our experience in treating CALMs using a picosecond 532-nm neodymium-doped yttrium aluminium garnet (PS 532 nm) laser. This is a retrospective case series of 16 patients with CALMs who were treated by a PS 532-nm laser (1-4 treatments, 4-8 weeks apart). Response as seen on clinical photographs was assessed by two independent dermatologists and graded on a scale of 0 (exacerbation) to 5 (95-100% improvement). Patient satisfaction and tolerance were documented at final visit. The results of 15 patients demonstrated significant improvement (average 3.43), and their satisfaction and tolerance levels were high. One patient had no response whatsoever to treatment. The PS 532-nm laser is a promising novel modality for the treatment of CALMs.

Long-Pulsed 532-Nm Neodymium-Doped Yttrium Aluminium Garnet Laser for Treatment of Facial Plane Warts in 160 Yemeni Patients.

PubMed

Alshami, Mohammad Ali; Mohana, Mona Jameel; Alshami, Ahlam Mohammad

2016-11-01

Warts in general and plane warts in particular pose a therapeutic challenge for dermatologists. Many treatment modalities exist, with variable success rates, side effect profiles, and precautions. The long-pulsed 532-nm neodymium-doped yttrium aluminium garnet (LP Nd:YAG) laser has not been previously used for this indication. This study was conducted to assess the efficacy and safety of the LP Nd:YAG laser for treating facial plane warts. A total of 160 Yemeni patients (62 women, 98 men; age range, 5-55 years) were exposed to 1 laser treatment session with the following parameters: wavelength, 532 nm; pulse duration, 20 millisecond; spot size, 2 to 3 mm; and fluence, 25 J/cm. The end point was graying or whitening of the lesion. Color photographs were taken before and immediately after treatment and at follow-up visits 1, 4, and 16 weeks after the laser session. An overall clearance rate of 92% after only one session was achieved, with minimal and transient side effects. The LP Nd:YAG laser is safe and effective for treating facial plane warts, with a success rate of 92% after only one session.

High resolution neodymium characterization along the Mediterranean Sea margins: implications for ɛNd modeling.

NASA Astrophysics Data System (ADS)

Ayache, Mohamed; Dutay, Jean-claude; Arsouze, Thomas; Jeandel, Catherine; Revillon, Sidonie

2016-04-01

An extensive compilation of published neodymium (Nd) concentrations and isotopic compositions (ɛNd) was realized in order to establish a new database and a map (using a high resolution geological map of the area) of the distribution of these parameters for all the Mediterranean margins. Data were extracted from different kinds of samples: river solid discharge deposited on the shelf, sedimentary material collected on the margin or geological material outcropping above or close to a margin. Additional analyses of surface sediments were done, in order to improve this dataset in key areas (e.g Sicilian strait). The Mediterranean margin Nd isotopic signatures vary from non-radiogenic values around the Gulf of Lions, (ɛNd values -11) to radiogenic values around the Aegean and the Levantine sub-basins up to +6. Using a high resolution regional oceanic model (1/12° of horizontal resolution), ɛNd distribution was simulated for the first time in the Mediterranean Sea. The high resolution of the model provides the opportunity to study in more details the processes governing the Nd isotope distribution in the marine environment. This work highlights that a significant interannual variability of ɛNd distribution in seawater could occur. In particular, important hydrological events such as the Eastern Mediterranean Transient (EMT), associated with deep water formed in the Aegean sub-basin, could induce a shift in Nd IC at intermediate depths that could be noticeable in the Western part of the basin. This highlights that the temporal and geographical variations of ɛNd could represent an interesting insight of Nd as a quasi-conservative tracer of water masses in the Mediterranean Sea, in particular in the context of paleo-oceanographic applications, i.e. to explore if EMT-type signatures occurred in the past (Roether et al., 2014, Gacic et al., 2011).

Spectroscopic Properties of Neodymium and Erbium-Doped Magnesium Oxide Ceramics

DTIC Science & Technology

2015-09-01

may contribute to the difference between the measured and expected values (such as varied hydration levels in the starting materials), there has...believe that such impurities forms from the thermal decomposition of the organic binders and dispersants used in the processing. We believe the

Structural aspects of calcium iron phosphate glass containing neodymium oxide

NASA Astrophysics Data System (ADS)

Li, Haijian; Liang, Xiaofeng; Wang, Cuiling; Yu, Huijun; Li, Zhen; Yang, Shiyuan

2014-06-01

Homogeneous glasses of the xNd2O3sbnd (100 - x)(12CaOsbnd 20Fe2O3sbnd 68P2O5) system were obtained within the 0 ⩽ x ⩽ 10 mol% composition range. The density and molar volume measurements helped to understand the structural changes occurring in these glasses. Vickers-hardness results showed that addition of Nd2O3 strengthened the crosslinking of the glass network. Spectra analysis indicated that Nd2O3 enters in the structure of the phosphate glasses as a network modifier. The depolymerization of the glass network by the addition of Nd2O3 is characterized by the increase in the concentration of pyrophosphate. The decrease of the Q1 terminal oxygen with increasing Nd2O3 content indicated that Psbnd Osbnd Nd bonds participated in the pyrophosphate glass structure, determined from the Raman spectra.

Effect of neodymium:yttrium-aluminum-garnet laser and fluoride on the acid demineralization of enamel.

PubMed

Braga, Sheila Regina Maia; de Oliveira, Elisabeth; Sobral, Maria Angela Pita

2017-02-01

The aim of the present study was to evaluate the protective effect of the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser and acidic phosphate fluoride (APF) on enamel erosion caused by hydrochloric acid. Fifty human enamel specimens were distributed according to the following treatments (n = 10): untreated (control), APF (1.23%) 4 min, Nd:YAG laser (100 mJ, 1 W, 10 Hz, 141.5 J/cm 2 ), APF + Nd:YAG laser, and Nd:YAG laser + APF. For 14 days the specimens were submitted to erosive challenge: 5 min in 3 mL hydrochloric acid (0.01 M, pH 2.2), rinsed with distilled water, and stored in artificial saliva for 3 h. This cycle was repeated four times per day. The calcium (Ca) loss was determined in demineralizing solution by atomic emission spectroscopy, and superficial roughness (Ra) was measured before and after the erosive challenge. The mean Ca loss was (mg/L, ± standard deviation): control 12.74 ± 3.33, APF 1.71 ± 0.11, laser 1.64 ± 0.08, APF + laser 1.38 ± 0.08, and laser + APF 1.48 ± 0.07. Kruskal-Wallis test showed a significant difference between the control and other groups. APF + laser showed minor loss of Ca. After the erosive challenge, the APF + laser group showed Ra alteration. A significant reduction in tooth dissolution was observed after fluoride application combined with Nd:YAG irradiation. © 2015 Wiley Publishing Asia Pty Ltd.

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

PubMed

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

2009-11-19

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

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

NASA Astrophysics Data System (ADS)

Betton, P. J.; Civetta, L.

1984-11-01

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

Cerium and Neodymium Isotope Fractionation in Geochemical Samples

NASA Astrophysics Data System (ADS)

Ohno, T.; Ishibashi, T.

2014-12-01

The study of naturally occurring isotopic variations of rare earth elements (REE) has a potentially significant influence in geochemical research fields with other traditional studies of REE. One of the key features of REE are their chemical similarities and gradual changes of ionic radius, which may make the isotopic variation of REE a potential tool to understand the mechanisms of isotopic fractionation in nature. Among the REE, geochemical and physicochemical features of Ce could be anomalous, because Ce could be present as the tetravalent (+IV) state as well as the common trivalent (+III) state of other REE. Since the oxidation state of Ce can change by reflecting the redox conditions of the environment, the measured differences in the degree of isotopic fractionation between Ce and other REE can provide unique information about the redox conditions. In this study, we developed a new analytical method to determine the mass-dependent isotopic fractionations of Ce and Nd in geochemical samples. The reproducibility of the isotopic ratio measurements on 142Ce/140Ce, 146Nd/144Nd and 148Nd/144Nd were 0.08‰ (2SD, n=25), 0.06‰ (2SD, n=39) and 0.12‰ (2SD, n=39), respectively. The present technique was applied to determine the variations of the Ce and Nd isotopic ratios for five geochemical reference materials (igneous rocks, JB-1a and JA-2; sedimentary rocks, JMn-1, JCh-1 and JDo-1). The resulting ratios for two igneous rocks (JB-1a and JA-2) and two sedimentary rocks (JMn-1 and JCh-1) did not vary significantly among the samples, whereas the Ce and Nd isotope ratios for the carbonate samples (JDo-1) were significantly higher than those for igneous and sedimentary rock samples. The 1:1 simple correlation between δ142Ce and δ146Nd indicates that there were no significant difference in the degree of isotopic fractionation between the Ce and Nd. This suggests that the isotopic fractionation for Ce found in the JDo-1 could be induced by physicochemical processes

The Effect of Neodymium: Yttrium Aluminum Garnet and Fractional Carbon Dioxide Lasers on Alopecia Areata: A Prospective Controlled Clinical Trial.

PubMed

Yalici-Armagan, Basak; Elcin, Gonca

2016-04-01

Effective treatment options for alopecia areata (AA) are missing. Whether lasers might be effective is a topic of debate. We aimed to evaluate whether neodymium: yttrium aluminum garnet (Nd:YAG) or fractional carbon dioxide lasers might stimulate the development of new hair. Thirty-two patients who had long-standing and treatment refractory diseases were recruited for the study. Three different patches on the scalp were selected, 1 of which served as control. The mean outcome measure was the hair count, which was calculated with the digital phototrichogram. Response was defined as at least 25% increase in the mean hair count at the treated patch compared with the control patch. At the end of the study, there was no statistically significant difference in the mean hair count for the 3 patches. In 7 of 32 patients (22%), an increase in the mean hair count was observed on the whole scalp including the control patch, which resulted in an improved Severity of Alopecia Tool (SALT) score. We have observed that Nd:YAG or fractional carbon dioxide lasers did not increase the mean hair count on the treated AA patches when compared with the control patch. However, an SALT score improvement in 22% of the patients suggested spontaneous remission.

Effect of laser peripheral iridotomy using argon and neodymium-YAG lasers on corneal endothelial cell density: 7-year longitudinal evaluation.

PubMed

Ono, Takashi; Iida, Masaharu; Sakisaka, Toshihiro; Minami, Keiichiro; Miyata, Kazunori

2018-03-01

To evaluate the changes in corneal endothelial cell density (ECD) over a 7-year period after laser peripheral iridotomy (LPI) using argon and neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. Retrospective case series. Eyes that underwent prophylactic LPI using argon and Nd:YAG lasers were followed up for 7 years. Central corneal endothelial cells were observed by use of noncontact specular microscopy preoperatively and at 1 and 7 years postoperatively. Changes in ECD and the associations between preoperative ECD and the total energy of the Nd:YAG laser were evaluated. Fifty-one eyes of 51 patients were followed up for 7 years. The ECD significantly decreased after LPI (P < 0.049), and the reduction rate at 1 year after the surgery (1.69 ± 4.80%, 95% CI: 0.34%-3.04%) was significantly higher than the annual reduction rates after 1 year (0.17 ± 0.85%/y, P = 0.036, 95% CI: -0.07% to 0.41%). No association was found between the preoperative ECD and the total laser energy. Long-term evaluation indicated that the reduction in ECD after argon-Nd:YAG laser LPI was present but small during the initial year and was negligible after 1 year.

Suppressing 1.06- μm spontaneous emission of neodymium ions using a novel tellurite all-solid photonic bandgap fiber

NASA Astrophysics Data System (ADS)

Tong, Hoang Tuan; Demichi, Daisuke; Nagasaka, Kenshiro; Suzuki, Takenobu; Ohishi, Yasutake

2018-05-01

In order to take advantage of the 1.3- μm emission of neodymium (Nd3+) ions for many practical applications, we propose a tellurite all-solid photonic bandgap fiber (ASPBGF) to filter out the competing emission at 1.06 μm which is most prominent in the emission spectrum of Nd3+ ion. A novel Nd3+-doped tellurite ASPBGF is fabricated by using our developed tellurite glasses which have high compatibility of thermal properties and their refractive index difference is 0.096 at 1320 nm. The fiber is designed with 4 layers of high-index rods to have low confinement loss. The measured transmission spectrum of a 2.2-cm-long section of the fabricated fiber exhibits high transmission bands near 0.75 and 1.33 μm (about -20 dB and -19 dB) and a low transmission band in the vicinity of 1.06 μm which is about -27 dB. By using our fabricated Nd3+-doped tellurite ASPBGF, it is demonstrated for the first time that the 1.06- μm emission peak due to the 4F3/2→4I11/2 transition of Nd3+ ions is greatly suppressed about 12 times as compared to that obtained by using a bulk samples with the same doping concentration.

Sporicidal effects of iodine-oxide thermite reaction products

NASA Astrophysics Data System (ADS)

Russell, Rod; Bless, Stephan; Blinkova, Alexandra; Chen, Tiffany

2012-03-01

Iodine pentoxide-aluminum thermite reactions have been driven by impacts at 1000 m/s on steel plates 3 mm or thicker. This reaction releases iodine gas that is known to be a sporicide. To test the impact reactions for sporicidal effects, reactions took place in closed chambers containing dried Bacillus subtilis spores. The reduction in colony-forming units was dependent on the exposure time; long exposure times resulted in a 105 decrease in germination rate. This was shown to be due to the gas exposure rather than the heat or turbulence. Sporicidal effectiveness was increased by adding neodymium and saran resin.

Long-pulsed 1064-nm neodymium:yttrium-aluminum-garnet laser treatment for refractory warts on hands and feet.

PubMed

Kimura, Utako; Takeuchi, Kaori; Kinoshita, Ayako; Takamori, Kenji; Suga, Yasushi

2014-03-01

Common warts (verruca vulgaris) are the most commonly seen benign cutaneous tumors. However, warts in the hands and feet regions often respond poorly to treatment, some are resistant to more than 6 months of treatment with currently available modalities, including cryotherapy, being defined as refractory warts. We investigated the usefulness of long-pulsed neodymium:yttrium-aluminum-garnet (LP-Nd:YAG) treatment for refractory warts. The clinical trial was conducted on 20 subjects (11 male, nine female) with a total of 34 lesions (periungual/subungual areas, plantar areas, fingers and/or toes). All the subjects suffered from refractory warts despite conventional treatments for more than 6 months. The patients were administrated up to six sessions of treatment, at intervals of 4 weeks between sessions, with an LP-Nd:YAG at a spot size of 5 mm, pulse duration of 15 msec and fluence of 150-185 J/cm(2) . Evaluation of the treatment results at 24 weeks after the initial treatment showed complete clearance of the refractory warts in 56% of the patients. Histological evaluation showed separation of the dermis and epidermis at the basement membrane with coagulated necrosis of the wart tissue in the lower epidermis, as well as coagulation and destruction of the blood vessels in the papillary dermis following the laser irradiation. No scarring, post-hyperpigmentary changes or serious adverse events were documented. Our preliminary results show that LP-Nd:YAG treatments are safe and effective for refractory warts of hands and feet, causing minimal discomfort, and is a viable treatment alternative. © 2014 Japanese Dermatological Association.

Di-μ-but-2-enoato-bis­[diaqua­bis(but-2-enoato)neodymium(III)] 2,6-diamino­purine disolvate

PubMed Central

Atria, Ana María; Astete, Alan; Garland, Maria Teresa; Baggio, Ricardo

2011-01-01

The title Nd complex [Nd2(C4H5O2)6(H2O)4]·2C5H6N6 is isotypic with two previously reported Dy and Ho isologues. It is composed of [Nd(crot)3(H2O)2]2 dimers [crot(onate) = but-2-enoate = C4H5O2], built up around symmetry centres and completed by 2,6-diamine­purine mol­ecules acting as solvates. The neodymium cations are coordinated by three chelating crotonato units and two water mol­ecules. One of the chelating carboxyl­ates acts also in a bridging mode, sharing one oxygen with both cations, and the final result is a pair of NdO9 tricapped prismatic polyhedra linked to each other through a central (Nd—O)2 loop. A most attractive aspect of the structures resides in the existence of a complex inter­molecular hydrogen-bonding interaction scheme involving two sets of tightly inter­linked, non-inter­secting one-dimensional structures, one of them formed by the [Nd(crot)3(H2O)2]2 dimers running along [100] and the second by the solvate mol­ecules evolving along [010]. PMID:22058842

Adsorption of arsenite and arsenate on binary and ternary magnetic nanocomposites with high iron oxide content

NASA Astrophysics Data System (ADS)

Ramos Guivar, Juan A.; Bustamante D., Angel; Gonzalez, J. C.; Sanches, Edgar A.; Morales, M. A.; Raez, Julia M.; López-Muñoz, María-José; Arencibia, Amaya

2018-10-01

Bare maghemite nanoparticles (Nps), binary, and ternary magnetic nanocomposites prepared with titanium dioxide (TiO2) and graphene oxide (GO) were synthesized by a facile and cheap co-precipitation chemical route, and used as magnetic nanoadsorbents to remove arsenite (As(III)) and arsenate (As(V)) from water. The structural, morphological, magnetic and surface properties were analyzed by XRD, TEM microscopy, FTIR and Raman vibrational spectroscopy, Mössbauer technique and N2 adsorption-desorption measurements. It was found that materials were composed of maghemite nanoparticles with crystallites diameters varying from 9 to 13 nm for bare Nps, binary and ternary nanocomposites, these nanocomposites contain a high percentage of maghemite phase (80%). The presence of TiO2 and GO in the binary and ternary materials was also confirmed. All the samples were found to show magnetic properties and a slight porosity, with a specific surface area that increases up to 82 m2/g when the metal oxides Nps were supported on GO. The aqueous arsenic adsorption performance was studied from kinetic and equilibrium point of view, and the pH adsorption capacity dependence was evaluated aiming to explain the adsorption mechanism. The three nanocomposites prepared in this work exhibit high adsorption capacity for arsenic species, with values of maximum adsorption capacity ranging from 83.1 to 110.4 mg/g for As(III) and from 90.2 to 127.2 mg/g for As(V) from bare to ternary nanocomposites, being possible to be separated with a permanent magnet of neodymium (Nd) in less than 10 min. Therefore, these nanosystems can be proposed as good adsorbents for both arsenic species from water.

Near-Infrared Neodymium Tag for Quantifying Targeted Biomarker and Counting Its Host Circulating Tumor Cells.

PubMed

Liu, Chunlan; Lu, Shu; Yang, Limin; Chen, Peijie; Bai, Peiming; Wang, Qiuquan

2017-09-05

Quantitative information on a targeted analyte in a complex biological system is the most basic premise for understanding its involved mechanisms, and thus precise diagnosis of a disease if it is a so-called biomarker. Here, we designed and synthesized a neodymium (Nd)-cored tag [1,4,7,10-tetraazacyclododecane-1,4,7-trisacetic acid (DOTA)-Nd complex together with a light-harvesting antenna aminofluorescein (AMF, λ ex/em = 494/520 nm), AMF-DOTA-Nd] with duplex signals, second near-infrared (NIR) window luminescence (λ em = 1065 nm, 2.5 μs), and stable isotopic mass ( 142 Nd). AMF-DOTA-Nd covalently linked with a urea-based peptidomimetic targeting group, 2-[3-(1,3-dicarboxypropyl)-ureido]pentanedioic acid (DUPA)-8-Aoc-Phe-Phe-Cys (DUPAaFFC) (DUPAaFFC-AMF-DOTA-Nd), allowing us to detect and quantify prostate-specific membrane antigen (PSMA) and its splice variants (total PSMA, tPSMA), which was set as an example of targeted biomarkers in this study, using NIR and inductively coupled plasma mass spectrometry (ICPMS) with the limit of detection (LOD) (3σ) of 0.3 ng/mL. When it was applied to the analysis of 80 blood samples from prostate cancer (PCa) and benign prostatic hyperplasia (BPH) patients as well as healthy volunteers, we found that 320 and 600 ng/mL tPSMA could be recommended as the threshold values to differentiate BPH from PCa and for the diagnosis of PCa. Moreover, PSMA-positive circulating tumor cells (CTCs) were counted using ICPMS being from 134 to 773 CTCs in the PCa blood samples of the Gleason score from 6 to 9 when the cell membrane-spanning mPSMA was tagged. Such a methodology developed could be expected to be applicable to other clinic-meaningful biomolecules and their host CTCs in liquid biopsy, when other specific targeting groups are modified to the NIR Nd tag.

Preparation and Characterization of High Temperature Superconductor Film Surfaces

DTIC Science & Technology

1993-10-27

Lanthanum Strontium Copper Oxide (LSCO) was also tested as a normal metal overlayer because of its compatibility with the high deposition temperature for...fabricate YBCO/ISCO SEB junctions using a variety of step heights (110 nm - 330 nm) on Neodymium Gallate (NGO) substrates. NGO was chosen as a...substrate because of its excellent lattice match to YBCO and its lack of crystal twinning Twinning had been a drawback of Lanthanum Aluminate (LAO)- L

Kinetics and its accompanying thermodynamics studies on simultaneous complexation of heterobimetallic neodymium (III) with zinc (II) and L-tryptophan in aquated DMF using 4f-4f absorption spectra.

PubMed

Huidrom, Bimola; Singh, N Rajmuhon

2014-01-24

The 4f-4f absorption spectra of the simultaneous heterobimetallic complexation of trivalent neodymium ion with l-tryptophan and divalent zinc ion in aquated DMF (50%, v/v) at pH 6.0 was recorded at the time interval of 1h. From the observed absorption spectra, the values of intensity parameters such as oscillator strength (P) and Judd-Ofelt intensity (Tλ) parameters, kinetics and thermodynamics parameters were evaluated. The rate constant increases with an increase in the temperature along with the oscillator strengths and Judd-Ofelt intensity parameters. The positive values of the change in the standard enthalpy (ΔH°) and entropy (ΔS°) indicate that the complexation is endothermic. The negative values of the change in the standard free energy (ΔG°) in the range from 293.15 K to 308.15 K, indicate that the reaction occurs spontaneously and hence the formation of heterobimetallic complex in the solution is favored kinetically and thermodynamically. Copyright © 2013 Elsevier B.V. All rights reserved.

Kinetics and its accompanying thermodynamics studies on simultaneous complexation of heterobimetallic neodymium (III) with zinc (II) and L-tryptophan in aquated DMF using 4f-4f absorption spectra

NASA Astrophysics Data System (ADS)

Huidrom, Bimola; Rajmuhon Singh, N.

2014-01-01

The 4f-4f absorption spectra of the simultaneous heterobimetallic complexation of trivalent neodymium ion with L-tryptophan and divalent zinc ion in aquated DMF (50%, v/v) at pH 6.0 was recorded at the time interval of 1 h. From the observed absorption spectra, the values of intensity parameters such as oscillator strength (P) and Judd-Ofelt intensity (Tλ) parameters, kinetics and thermodynamics parameters were evaluated. The rate constant increases with an increase in the temperature along with the oscillator strengths and Judd-Ofelt intensity parameters. The positive values of the change in the standard enthalpy (ΔH°) and entropy (ΔS°) indicate that the complexation is endothermic. The negative values of the change in the standard free energy (ΔG°) in the range from 293.15 K to 308.15 K, indicate that the reaction occurs spontaneously and hence the formation of heterobimetallic complex in the solution is favored kinetically and thermodynamically.

A low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminium garnet laser for the treatment of café-au-lait macules.

PubMed

Kim, Hyeong-Rae; Ha, Jeong-Min; Park, Min-Soo; Lee, Young; Seo, Young-Joon; Kim, Chang-Deok; Lee, Jeung-Hoon; Im, Myung

2015-09-01

Café-au-lait macules (CALMs) are a common pigmentary disorder. Although a variety of laser modalities have been used to treat CALMs, their efficacies vary and dyspigmentation may develop. We evaluated the clinical efficacy and safety of a low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminium garnet (Nd:YAG) laser for the treatment of CALMs. In a preliminary investigation, 6 patients underwent a split-lesion comparative study with 532- and 1064-nm Q-switched Nd:YAG laser treatment. In total, 32 patients with 39 CALMs were enrolled in a subsequent prospective trial to evaluate the treatment with a low-fluence 1064-nm Q-switched Nd:YAG laser. In the preliminary study, the 1064-nm treatment group had a more favorable response and a shorter recovery time. In a subsequent prospective trial of a 1064-nm laser, 74.4% of the lesions showed a clinical response with clearance of ≥50.0%. The treatment regimen was well tolerated; 15.4% of patients experienced adverse events. The study participants were followed for 6 months, and there were no relevant treatment controls in the prospective trial group. Low-fluence 1064-nm Q-switched Nd:YAG laser therapy afforded good clinical improvement for treating CALMs. Copyright © 2015 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

Synthesis and physico-chemical studies on neodymium(III) and samarium(III) complexes with tetraaza macrocyclic ligands

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

Goel, S.; Pandey, U.K.; Pandey, O.P.

1988-05-01

Reactions of neodymium trichloride and samarium trichloride with 6,7,13,14-R/sub 4/ - 3,10-X/sub 2/-(14)-5,7,12,14-tetraene-1,5,8,12-N/sub 4/-(2,4,9,11-N/sub 4/) (R = CH/sub 3/, X = 0 (L/sub 1//sup (1)/); R = C/sub 6/H/sub 5/, X = O (L/sub 1//sup (2)/); R = CH/sub 3/, X = S(L/sub 2//sup (1)/)) and R = C/sub 6/H/sub 5/, X = S(/sub 2//sup (2)/)) have been studied in ethanol and complexes of the type (M(L/sub 1//sup (1)/ or L/sub 1//sup (2)/))Cl/sub 3/ and (M(L/sub 2//sup (1)/ or L/sub 2//sup (2)/)(H/sub 2/O)/sub 2/)Cl/sub 3/ (M = Nd(III) and Sm(III)) have been isolated. In addition, macrocyclic complexes of Nd(III) andmore » Sm(III) with another series of tetraaza ligands, viz, 5,6,11,12-R/sub 4/-3,8-X/sub 2/-(12)-4,6,10,12-tetraene-1,4,7,10-N/sub 4/-(2,9-N/sub 2/) (R = CH/sub 3/, X = O (L/sub 3//sup (1)/); R = C/sub 6/H/sub 5/, X = O(L/sub 3//sup (2)/); R = CH/sub 3/, X = S(L/sub 4//sup (1)/); R = C/sub 6/H/sub 5/, X = S(L/sub 4//sup (2)/)), formulated as (M(L/sub 3//sup (1)/, L/sub 3//sup (2)/, L/sub 4//sup (1)/ or L/sub 4//sup (2)/)(H/sub 2/O)/sub 2/)Cl/sub 3/ (M = Nd(III) and Sm(III)) have been prepared by template condensation of Nd(III) and Sm(III) complexes of diacetylbis(semicarbazonethiosemicarbazone) or benzilibis(semicarbazonethiosemicarbazone) with diacetyl or benzil. The complexes have been identified by elemental analysis, electrical conductance, spectral and thermal measurements.« less

Pulmonary Laser Metastasectomy by 1318-nm Neodymium-Doped Yttrium-Aluminum Garnet Laser: A Retrospective Study About Laser Metastasectomy of the Lung.

PubMed

Porrello, Calogero; Gullo, Roberto; Vaglica, Antonino; Scerrino, Gregorio; Salamone, Giuseppe; Licari, Leo; Raspanti, Cristina; Gulotta, Eliana; Gulotta, Gaspare; Cocorullo, Gianfranco

2018-04-01

The lungs are among the first organ affected by remote metastases from many primary tumors. The surgical resection of isolated pulmonary metastases represents an important and effective element of therapy. This is a retrospective study about our entire experience with pulmonary resection for metastatic cancer using 1318-nm neodymium-doped yttrium-aluminum garnet laser. In this single-institution study, we retrospectively analyzed a group of 209 patients previously treated for primary malignant solid tumors. We excluded 103 patients. The number and location of lesions in the lungs was determined using chest computed tomography and positron emission tomography-computed tomography. Disseminated malignancy was excluded. All pulmonary laser resections are performed via an anteroaxillary muscle-sparing thoracotomy. All lesions were routinely removed by laser with a small (5-10 mm) margin of the healthy lung. Patients received systematic lymph node sampling with intraoperative smear cytology of sampled lymph nodes. Mortality at 2 years from the first surgery is around 20% (10% annually). This value increases to 45% in the third year. The estimated median survival for patients who underwent the first surgery is reported to be approximately 42 months. Our results show that laser resection of lung metastases can achieve good result, in terms of radical resection and survival, as conventional surgical metastasectomy. The great advantage is the possibility of limiting the damage to the lung. Stapler resection of a high number of metastases would mutilate the lung.

Beneficial Effect of Low Fluence 1,064 nm Q-Switched Neodymium:Yttrium-Aluminum-Garnet Laser in the Treatment of Senile Lentigo

PubMed Central

Nam, Jae-Hui; Kim, Han-Saem; Lee, Ga-Young

2017-01-01

Background Low fluence 1,064 nm Q-switched (QS) Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) laser treatment, also known as laser toning, is widely used for pigmentary disorders. There has been no reliable evaluation of the effect of low fluence 1,064 nm QS Nd:YAG laser for senile lentigo. Objective To investigate the beneficial effect of low fluence 1,064 nm QS Nd:YAG laser in the treatment of senile lentigo on the face. Methods A retrospective review was conducted on patients treated only with repetitive low fluence 1,064 nm QS Nd:YAG laser. Among them, 12 patients with multiple senile lentigines before treatment were included. All side effects were recorded to assess the safety of the modality. Results Mean age was 56.1±7.8 years old and male-to-female ratio was 1:11. Mean treatment fluence was 1.62±0.16 J/cm2 and mean total treatment session was 8.8±2.6. Mean interval period between each session was 28.0±11.4 days and mean treatment session to reach marked and near total improvement was 8.7±2.8. At the final visit, seven of 12 (58.3%) patients reached marked and near total improvement, and three of 12 (25.0%) reached moderate improvement. No side effects occurred. Conclusion Repetitive low fluence 1,064 nm QS Nd:YAG laser treatment may be an effective and safe optional modality for senile lentigo. PMID:28761290

Integration of optically active Neodymium ions in Niobium devices (Nd:Nb): quantum memory for hybrid quantum entangled systems

NASA Astrophysics Data System (ADS)

Nayfeh, O. M.; Chao, D.; Djapic, N.; Sims, P.; Liu, B.; Sharma, S.; Lerum, L.; Fahem, M.; Dinh, V.; Zlatanovic, S.; Lynn, B.; Torres, C.; Higa, B.; Moore, J.; Upchurch, A.; Cothern, J.; Tukeman, M.; Barua, R.; Davidson, B.; Ramirez, A. D.; Rees, C. D.; Anant, V.; Kanter, G. S.

2017-08-01

Optically active rare-earth Neodymium (Nd) ions are integrated in Niobium (Nb) thin films forming a new quantum memory device (Nd:Nb) targeting long-lived coherence times and multi-functionality enabled by both spin and photon storage properties. Nb is implanted with Nd spanning 10-60 keV energy and 1013-1014 cm-2 dose producing a 1- 3% Nd:Nb concentration as confirmed by energy-dispersive X-ray spectroscopy. Scanning confocal photoluminescence (PL) at 785 nm excitation are made and sharp emission peaks from the 4F3/2 -< 4I11/2 Nd3+ transition at 1064-1070 nm are examined. In contrast, un-implanted Nb is void of any peaks. Line-shapes at room temperature are fit with Lorentzian profiles with line-widths of 4-5 nm and 1.3 THz bandwidth and the impacts of hyperfine splitting via the metallic crystal potential are apparent and the co-contribution of implant induced defects. With increasing Nd from 1% to 3%, there is a 0.3 nm red shift and increased broadening to a 4.8 nm linewidth. Nd:Nb is photoconductive and responds strongly to applied fields. Furthermore, optically detected magnetic resonance (ODMR) measurements are presented spanning near-infrared telecom band. The modulation of the emission intensity with magnetic field and microwave power by integration of these magnetic Kramer type Nd ions is quantified along with spin echoes under pulsed microwave π-π/2 excitation. A hybrid system architecture is proposed using spin and photon quantum information storage with the nuclear and electron states of the Nd3+ and neighboring Nb atoms that can couple qubit states to hyperfine 7/2 spin states of Nd:Nb and onto NIR optical levels excitable with entangled single photons, thus enabling implementation of computing and networking/internet protocols in a single platform.

Development of Ceramic Solid-State Laser Host Material

NASA Technical Reports Server (NTRS)

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

2009-01-01

Polycrystalline ceramic laser materials are gaining importance in the development of novel diode-pumped solid-state lasers. Compared to single-crystals, ceramic laser materials offer advantages in terms of ease of fabrication, shape, size, and control of dopant concentrations. Recently, we have developed Neodymium doped Yttria (Nd:Y2O3) as a solid-state ceramic laser material. A scalable production method was utilized to make spherical non agglomerated and monodisperse metastable ceramic powders of compositions that were used to fabricate polycrystalline ceramic material components. This processing technique allowed for higher doping concentrations without the segregation problems that are normally encountered in single crystalline growth. We have successfully fabricated undoped and Neodymium doped Yttria material up to 2" in diameter, Ytterbium doped Yttria, and erbium doped Yttria. We are also in the process of developing other sesquioxides such as scandium Oxide (Sc2O3) and Lutesium Oxide (Lu2O3) doped with Ytterbium, erbium and thulium dopants. In this paper, we present our initial results on the material, optical, and spectroscopic properties of the doped and undoped sesquioxide materials. Polycrystalline ceramic lasers have enormous potential applications including remote sensing, chem.-bio detection, and space exploration research. It is also potentially much less expensive to produce ceramic laser materials compared to their single crystalline counterparts because of the shorter fabrication time and the potential for mass production in large sizes.

Superconducting composite with multilayer patterns and multiple buffer layers

DOEpatents

Wu, Xin D.; Muenchausen, Ross E.

1993-01-01

An article of manufacture including a substrate, a patterned interlayer of a material selected from the group consisting of magnesium oxide, barium-titanium oxide or barium-zirconium oxide, the patterned interlayer material overcoated with a secondary interlayer material of yttria-stabilized zirconia or magnesium-aluminum oxide, upon the surface of the substrate whereby an intermediate article with an exposed surface of both the overcoated patterned interlayer and the substrate is formed, a coating of a buffer layer selected from the group consisting of cerium oxide, yttrium oxide, curium oxide, dysprosium oxide, erbium oxide, europium oxide, iron oxide, gadolinium oxide, holmium oxide, indium oxide, lanthanum oxide, manganese oxide, lutetium oxide, neodymium oxide, praseodymium oxide, plutonium oxide, samarium oxide, terbium oxide, thallium oxide, thulium oxide, yttrium oxide and ytterbium oxide over the entire exposed surface of the intermediate article, and, a ceramic superco n FIELD OF THE INVENTION The present invention relates to the field of superconducting articles having two distinct regions of superconductive material with differing in-plane orientations whereby the conductivity across the boundary between the two regions can be tailored. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

Short-pulse neodymium:yttrium-aluminium garnet (Nd:YAG 1064nm) laser irradiation photobiomodulates mitochondria activity and cellular multiplication of Paramecium primaurelia (Protozoa).

PubMed

Amaroli, Andrea; Benedicenti, Alberico; Ravera, Silvia; Parker, Steven; Selting, Wayne; Panfoli, Isabella; Benedicenti, Stefano

2017-10-01

Few studies exist to explore the potential photobiomodulation (PBM) effect of neodymium:yttrium-aluminium garnet (Nd:YAG) laser irradiation using a flat-top handpiece delivery system. In this study, we explored the photobiomodulation effect of that laser, on Paramecium primaurelia. The parameters for the different study groups were: 0.50W, 10Hz, 100msp, 30J/cm 2 ; 0.75W, 10Hz, 100msp, 45J/cm 2 ; 1.00W, 10Hz, 100msp, 60J/cm 2 ; 1.25W, 10Hz, 100msp, 75J/cm 2 and 1.50W, 10Hz, 100msp, 90J/cm 2 . Our results suggest that only the parameter 0.5W, 10Hz, 100msp, 30J/cm 2 positively photobiomodulates the Paramecium cells inducing an increment in oxygen consumption, endogenous ATP synthesis and fission rate rhythm. Applying the laser energy with parameters of 1.25W, 10Hz, 100msp, 75J/cm 2 and 1.50W, 10Hz, 100msp, 90J/cm 2 , induce adverse effect on the Paramecium cells, which protect themselves through the increase in Heat Shock Protein-70 (HSP70). The data presented in our work support our assumption that, when using appropriate parameters of irradiation, the 1064nm Nd:YAG laser with flat-top handpiece could be a valuable aid for effective clinical application of PBM. Copyright © 2017 Elsevier GmbH. All rights reserved.

Clinical evaluation of neodymium-iron-boron (Ne2Fe14B) rare earth magnets in the treatment of mid line diastemas

PubMed Central

Manoj-Kumar, Mitta; Gowri-Sankar, Singaraju; Chaitanya, Nellore; Vivek-Reddy, Ganugapanta; Venkatesh, Nettam

2016-01-01

Background To evaluate the closure of midline diastema using the Neodymium-Iron-Boron magnets and to compare the treatment duration of midline diastemas with the use of magnets compared to regular orthodontic treatment. Material and Methods Thirty patients with age group 12 to 30 years with the midline diastema ranging from 0.5 to 3mm were selected. These patients were divided into two groups. Diastema closure in one group was accomplished by conventional method, in other group was done with Ne2Fe14B magnets. These magnets were fitted to the labial surfaces of the maxillary central incisors such a way that the opposite poles of the magnets face each other. At each appointment, study models and radiographs were taken for study subjects and the midline diastema was measured using digital vernier calipers on the study models obtained. Descriptive statistics carried out using Paired t-test. Results Subjects treated with Ne2Fe14B magnets showed a significant difference compared to fixed orthodontic appliance subjects with respect to time of closure, rate of space closure and incisal inclination. Significant difference between 2 groups with reduction of 64.6 days in time to diastema closure in subjects treated with Ne2Fe14B magnets (P<0.05). Conclusions Ne2Fe14B magnets more efficient in complete closure of mid line diastema in less duration of time. Key words:Midline diastema, Ne2Fe14B magnets, rare earth magnets, space closure. PMID:27034757

Melanogenesis inhibition in mice using a low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser: a pilot study.

PubMed

Nam, Jae-Hui; Min, Joon Hong; Kim, Wang-Kyun; Yim, Sunmin; Kim, Won-Serk

2017-07-01

A low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser, or laser toning, has yielded favorable outcomes in various benign pigmented disorders. However, the exact mechanism of action of laser toning has not been fully elucidated. We sought to determine the inhibitory effect of laser toning on melanogenesis and to assess how laser passes influence the outcomes. To produce perceptible pigmentation, nine HRM-2 melanin-possessing hairless mice were treated with ultraviolet (UV) B radiation on the dorsal skin. This was followed by zero, two, four, or six passes of laser toning twice in 2 weeks on each designated quadrant. The spectrophotometric values and pigmentation-related protein expressions were measured. Pigment changes were found in the mice skin using the Fontana-Masson stain for histopathological analysis. Four- and six-pass laser toning significantly improved the lightness compared to that in the unirradiated control (p < 0.002). The Fontana-Masson stain showed that melanin was considerably decreased in laser-irradiated skin. As the number of laser passes increased, the expression of tyrosinase decreased (p < 0.008). The following parameters also decreased in proportion to the number of laser passes: MITF, TRP-1, TRP-2, p-ERK, and p-Akt. In contrast, TGF-β increased in proportion to the number of laser passes. However, the changes in these six proteins were not statistically significant. Our study demonstrates that laser toning improves skin pigmentation with increased number of passes in a dose-dependent manner. This effect is mediated by tyrosinase inhibition.

The structure and stability of aqueous rare-earth elements in hydrothermal fluids: New results on neodymium(III) aqua and chloroaqua complexes in aqueous solutions to 500 °C and 520 MPa

USGS Publications Warehouse

Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

2009-01-01

X-ray absorption spectroscopy (XAS) measurements were made at the Nd L3-edge on neodymium(III) aqua and chloroaqua complexes in low pH aqueous solutions from 25 to 500????C and up to 520??MPa. Analysis of the extended X-ray absorption fine structure of the XAS spectra measured from a 0.07??m Nd/0.16??m HNO3 aqueous solution reveals a contraction of the Nd-O distance of the Nd3+ aqua ion at a uniform rate of ~ 0.013????/100????C and a uniform reduction of the number of coordinated H2O molecules from 10.0 ?? 0.9 to 7.4 ?? 0.9 over the range from 25 to 500????C and up to 370??MPa. The rate of reduction of the first-shell water molecules with temperature for Nd3+ (26%) is intermediate between the rate for the Gd3+ aqua ion (22% from 25 to 500????C) and the rates for the Eu3+ (29% from 25 to 400????C) and the Yb3+ aqua ions (42% from 25 to 500????C) indicating an intermediate stability of the Nd3+ aqua ion consistent with the tetrad effect. Nd L3-edge XAS measurements of 0.05??m NdCl3 aqueous solution at 25 to 500????C and up to 520??MPa show that stepwise inner-sphere complexes most likely of the type Nd(H2O)?? - nCln+3 - n occur in the solution at elevated temperatures, where ?? ??? 9 at 150????C decreasing to ~ 6 at 500????C and the number of chloride ions (n) of the chloroaqua complexes increases uniformly with temperature from 1.2 ?? 0.2 to 2.0 ?? 0.2 in the solution upon increase of temperature from 150 to 500????C. Conversely, the number of H2O ligands of Nd(H2O)?? - nCln+3 - n complexes is uniformly reduced with temperature from 7.5 ?? 0.8 to 3.7 ?? 0.3 in the aqueous solution, in the same temperature range. These data show greater stability of neodymium(III) than gadolinium(III) and ytterbium(III) chloride complexes in low pH aqueous solutions at elevated temperatures. Our data suggest a greater stability of aqueous light REE than that of heavy REE chloride complexes in low pH fluids at elevated temperatures consistent with REE analysis of fluids from deep

Deep Ocean Circulation and Nutrient Contents from Atlantic-Pacific Gradients of Neodymium and Carbon Isotopes During the Last 1 Ma

NASA Astrophysics Data System (ADS)

Piotrowski, A. M.; Elderfield, H.; Howe, J. N. W.

2014-12-01

The last few million years saw changing boundary conditions to the Earth system which set the stage for bi-polar glaciation and Milankovich-forced glacial-interglacial cycles which dominate Quaternary climate variability. Recent studies have highlighted the relative importance of temperature, ice volume and ocean circulation changes during the Mid-Pleistocene Transition at ~900 ka (Elderfield et al., 2012, Pena and Goldstein, 2014). Reconstructing the history of global deep water mass propagation and its carbon content is important for fully understanding the ocean's role in amplifying Milankovich changes to cause glacial-interglacial transitions. A new foraminiferal-coating Nd isotope record from ODP Site 1123 on the deep Chatham Rise is interpreted as showing glacial-interglacial changes in the bottom water propagation of Atlantic-sourced waters into the Pacific via the Southern Ocean during the last 1 million years. This is compared to globally-distributed bottom water Nd isotope records; including a new deep western equatorial Atlantic Ocean record from ODP Site 929, as well as published records from ODP 1088 and Site 1090 in the South Atlantic (Pena and Goldstein, 2014), and ODP 758 in the deep Indian Ocean (Gourlan et al., 2010). Atlantic-to-Pacific gradients in deep ocean neodymium isotopes are constructed for key time intervals to elucidate changes in deep water sourcing and circulation pathways through the global ocean. Benthic carbon isotopes are used to estimate deep water nutrient contents of deep water masses and constrain locations and modes of deep water formation. References: Elderfield et al. Science 337, 704 (2012) Pena and Goldstein, Science 345, 318 (2014) Gourlan et al., Quaternary Science Reviews 29, 2484-2498 (2010)

In vitro study concerning the efficiency of the frequency-doubled double-pulse Neodymium:YAG laser (FREDDY) for lithotripsy of calculi in the urinary tract.

PubMed

Zörcher, T; Hochberger, J; Schrott, K M; Kühn, R; Schafhauser, W

1999-01-01

In a preclinical study we have tested both in vitro and in vivo, a new type of pulsed solid-state laser system that has not been applied in urology so far and has been developed for optimized intracorporal lithotripsy of biliary, salivary, and urinary calculi. Sixty one calculi from the human urinary tract were split in vitro into fragments with a remaining particle size of Neodymium:YAG laser. In a supplementary animal test, the bladder mucosa of five rabbits was directly exposed to a highly rated laser beam to be able to assess the tissue lesion potential of the system. All the 61 urinary calculi with different composition were successfully split in vitro within a short period of time (2.5 +/- 4.6 minutes). During histopathologic examination of the exposed bladder walls of the rabbits only a small tissue lesion potential with urothelium changes exclusively at the surface was ascertained. The high degree of fragmentation efficiency, the purchase and maintenance costs, which due to its design are substantially lower in comparison to other laser lithotriptors, and the high degree of safety during application make this new laser a real alternative not only to the present laser lithotripsy systems but also to common ballistic lithotriptors. Copyright 1999 Wiley-Liss, Inc.

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

NASA Astrophysics Data System (ADS)

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

2015-11-01

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

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

In situ affinity purification of his-tagged protein A from Bacillus megaterium cultivation using recyclable superparamagnetic iron oxide nanoparticles.

PubMed

Gädke, Johannes; Kleinfeldt, Lennart; Schubert, Chris; Rohde, Manfred; Biedendieck, Rebekka; Garnweitner, Georg; Krull, Rainer

2017-01-20

This paper discusses the use of recyclable functionalized nanoparticles for an improved downstream processing of recombinant products. The Gram-positive bacterium Bacillus megaterium was used to secrete recombinant protein A fused to a histidine tag into the culture supernatant in shaker flasks. Superparamagnetic iron oxide nanoparticles functionalized with 3-glycidoxypropyl-trimethoxysilane-coupled-nitrilotriacetic-acid groups (GNTA-SPION) were synthesized and added directly to the growing culture. After 10min incubation time, >85% of the product was adsorbed onto the particles. The particles were magnetically separated using handheld neodymium magnets and the product was eluted. The GNTA-SPION were successfully regenerated and reused in five consecutive cycles. In the one-step purification, the purity of the product reached >99.9% regarding protein A. A very low particle concentration of 0.5g/L was sufficient for effective product separation. Bacterial growth was not influenced negatively by this concentration. Particle analysis showed similar properties between freshly synthesized and regenerated GNTA-SPION. The overall process efficiency was however influenced by partial disintegration of particle agglomerates and thus loss of particles. The demonstration of very fast in situ product removal from growing bacterial culture combined with a very high product purity within one step shows possibilities for automated large scale purification combined with recycling of biomass. Copyright © 2016 Elsevier B.V. All rights reserved.

International strategic minerals inventory summary report; rare-earth oxides

USGS Publications Warehouse

Jackson, W.D.; Christiansen, Grey

1993-01-01

Bastnaesite, monazite, and xenotime are currently the most important rare-earth minerals. Bastnaesite occurs as a primary mineral in carbonatites. Monazite and xenotime also can be found in primary deposits but are recovered principally from heavy-mineral placers that are mined for titanium or tin. Each of these minerals has a different composition of the 15 rare-earth elements. World resources of economically exploitable rare-earth oxides (REO) are estimated at 93.4 million metric tons in place, composed of 93 percent in primary deposits and 7 percent in placers. The average mineral composition is 83 percent bastnaesite, 13 percent monazite, and 4 percent of 10 other minerals. Annual global production is about 67,000 metric tons of which 41 percent is from placers and 59 percent is from primary deposits; mining methods consist of open pits (94 percent) and dredging (6 percent). This output could be doubled if the operations that do not currently recover rare earths would do so. Resources are more than sufficient to meet the demand for the predictable future. About 52 percent of the world's REO resources are located in China. Ranking of other countries is as follows: Namibia (22 percent), the United States (15 percent), Australia (6 percent), and India (3 percent); the remainder is in several other countries. Conversely, 38 percent of the production is in China, 33 percent in the United States, 12 percent in Australia, and 5 percent each in Malaysia and India. Several other countries, including Brazil, Canada, South Africa, Sri Lanka, and Thailand, make up the remainder. Markets for rare earths are mainly in the metallurgical, magnet, ceramic, electronic, chemical, and optical industries. Rare earths improve the physical and rolling properties of iron and steel and add corrosion resistance and strength to structural members at high temperatures. Samarium and neodymium are used in lightweight, powerful magnets for electric motors. Cerium and yttrium increase the

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

NASA Astrophysics Data System (ADS)

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

2016-11-01

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

Efficacy of the Q-switched Neodymium: Yttrium Aluminum Garnet Laser in the Treatment of Blue-black Amateur and Professional Tattoos

PubMed Central

Lakshmi, Chembolli; Krishnaswamy, Gayathri

2015-01-01

Background: Q-switched neodymium: yttrium aluminum garnet (Nd: YAG) laser at a wavelength of 1064 nm primarily targets dermal melanin and black tattoo ink. Recent studies have shown that this laser is effective in treating black tattoos. There are few studies conducted in India for the same. Aim: The aim was to assess the effectiveness of Q-switched Nd: YAG laser (QSNYL) in the treatment of blue-black tattoos following 3 treatment sessions. Materials and Methods: This study, a prospective interventional study included a total of 12 blue-black tattoos. Following informed consent for the procedure, as well as for photographs, a questionnaire was administered, and improvement perceived by the patient was recorded. In addition, global assessment score (GAS) by a blinded physician was also recorded. Photographs were taken at baseline and at every follow-up. Each patient underwent three treatment sessions with 1064 nm QSNYL at 4–6 weekly intervals. Fluences ranged from 1.8 to 9 J/cm2. The follow-up was done monthly for 4 months from the first treatment session. The response was assessed by patient assessment (PA) and GAS by comparing photographs. Results: After three treatment sessions, although no patient achieved clearance, most patients showed good response with few adverse effects. An average of 64.1% (GAS) and 54.2% (PA) improvement was observed in 12 tattoos. Tattoos more than 10-year-old showed quicker clearing than those less than 10-year-old. Amateur tattoos also showed a better response in comparison to professional tattoos. Conclusion: Totally, 1064 nm QSNYL is safe and effective for lightening blue-black tattoos in pigmented Indian skin. All patients achieved near complete clearance following the continuation of treatment (an average of six sessions) although this was spaced at longer intervals. PMID:26677271

Efficacy of the Q-switched Neodymium: Yttrium Aluminum Garnet Laser in the Treatment of Blue-black Amateur and Professional Tattoos.

PubMed

Lakshmi, Chembolli; Krishnaswamy, Gayathri

2015-01-01

Q-switched neodymium: yttrium aluminum garnet (Nd: YAG) laser at a wavelength of 1064 nm primarily targets dermal melanin and black tattoo ink. Recent studies have shown that this laser is effective in treating black tattoos. There are few studies conducted in India for the same. The aim was to assess the effectiveness of Q-switched Nd: YAG laser (QSNYL) in the treatment of blue-black tattoos following 3 treatment sessions. This study, a prospective interventional study included a total of 12 blue-black tattoos. Following informed consent for the procedure, as well as for photographs, a questionnaire was administered, and improvement perceived by the patient was recorded. In addition, global assessment score (GAS) by a blinded physician was also recorded. Photographs were taken at baseline and at every follow-up. Each patient underwent three treatment sessions with 1064 nm QSNYL at 4-6 weekly intervals. Fluences ranged from 1.8 to 9 J/cm(2). The follow-up was done monthly for 4 months from the first treatment session. The response was assessed by patient assessment (PA) and GAS by comparing photographs. After three treatment sessions, although no patient achieved clearance, most patients showed good response with few adverse effects. An average of 64.1% (GAS) and 54.2% (PA) improvement was observed in 12 tattoos. Tattoos more than 10-year-old showed quicker clearing than those less than 10-year-old. Amateur tattoos also showed a better response in comparison to professional tattoos. Totally, 1064 nm QSNYL is safe and effective for lightening blue-black tattoos in pigmented Indian skin. All patients achieved near complete clearance following the continuation of treatment (an average of six sessions) although this was spaced at longer intervals.

Combined effects of long-pulsed neodymium-yttrium-aluminum-garnet laser, diprospan and 5-fluorouracil in the treatment of keloid scars.

PubMed

Chen, Xiao-E; Liu, Juan; Bin Jameel, Afzaal Ahmed; Valeska, Maya; Zhang, Jia-An; Xu, Yang; Liu, Xing-Wu; Zhou, Hong; Luo, Dan; Zhou, Bing-Rong

2017-06-01

Keloids are benign tumors that originate from scar tissues, but they usually overgrow beyond the original wounds. In a three-month single-center clinical trial, 69 patients were randomly divided into three groups. Patients in group 1 were treated with intralesional injection of diprospan (2 mg betamethasone disodium phosphate and 5 mg betamethasone dipropionate in 1 ml) with one-month intervals for three months. Patients in groups 2 and 3 were injected with a combination of 0.5 ml 5-fluorouracil (5-FU; 25 mg/ml) and diprospan as above for three months also. Prior to each injection, the keloids of patients in group 3 were additionally irradiated by a 1,064-nm neodymium-yttrium-aluminum-garnet (Nd:YAG) laser with a single pulse at an energy density of 90-100 J/cm 2 and a pulse width of 12 msec. Clinical responses were evaluated by patient self-assessment and overall assessment by an observer according to the clinical signs of erythema, pruritus and pliability. A total of sixty-two patients completed the tests of the present study. At 2 and 3 months, the patients in all treatment groups showed an acceptable improvement in nearly all measurements. At the end of the study, the erythema and toughness score was significantly reduced and itch reduction was significantly greater in the diprospan + 5-FU + Nd:YAG group when compared to those in the other groups (P<0.05 for all indexes). The acceptable responses (good to excellent improvements) reported by blinded observers were as follows: 12% in the diprospan group, 48% in the diprospan + 5-FU group and 69% in the diprospan + 5-FU + Nd:YAG group. All of the results indicated that the combination of diprospan + 5-FU + Nd:YAG was the most efficacious therapy for keloid scars.

Combined effects of long-pulsed neodymium-yttrium-aluminum-garnet laser, diprospan and 5-fluorouracil in the treatment of keloid scars

PubMed Central

Chen, Xiao-E; Liu, Juan; Bin Jameel, Afzaal Ahmed; Valeska, Maya; Zhang, Jia-An; Xu, Yang; Liu, Xing-Wu; Zhou, Hong; Luo, Dan; Zhou, Bing-Rong

2017-01-01

Keloids are benign tumors that originate from scar tissues, but they usually overgrow beyond the original wounds. In a three-month single-center clinical trial, 69 patients were randomly divided into three groups. Patients in group 1 were treated with intralesional injection of diprospan (2 mg betamethasone disodium phosphate and 5 mg betamethasone dipropionate in 1 ml) with one-month intervals for three months. Patients in groups 2 and 3 were injected with a combination of 0.5 ml 5-fluorouracil (5-FU; 25 mg/ml) and diprospan as above for three months also. Prior to each injection, the keloids of patients in group 3 were additionally irradiated by a 1,064-nm neodymium-yttrium-aluminum-garnet (Nd:YAG) laser with a single pulse at an energy density of 90–100 J/cm2 and a pulse width of 12 msec. Clinical responses were evaluated by patient self-assessment and overall assessment by an observer according to the clinical signs of erythema, pruritus and pliability. A total of sixty-two patients completed the tests of the present study. At 2 and 3 months, the patients in all treatment groups showed an acceptable improvement in nearly all measurements. At the end of the study, the erythema and toughness score was significantly reduced and itch reduction was significantly greater in the diprospan + 5-FU + Nd:YAG group when compared to those in the other groups (P<0.05 for all indexes). The acceptable responses (good to excellent improvements) reported by blinded observers were as follows: 12% in the diprospan group, 48% in the diprospan + 5-FU group and 69% in the diprospan + 5-FU + Nd:YAG group. All of the results indicated that the combination of diprospan + 5-FU + Nd:YAG was the most efficacious therapy for keloid scars. PMID:28588688

Neodymium and carbon isotopic fingerprints of warm Pliocene circulation throughout the deep Atlantic

NASA Astrophysics Data System (ADS)

Riesselman, C. R.; Scher, H. D.; Dowsett, H. J.; Robinson, M. M.

2013-12-01

The mid-Piacenzian age of the Pliocene is the most recent interval in Earth's history to sustain global warmth within the range predicted for the 21st century. To understand this interval, the USGS PRISM Project has developed a reconstruction of global conditions at 3.264-3.025 Ma, which includes a significant North Atlantic warm SST anomaly coupled with increased evaporation. Warm anomalies are also detected in the deep ocean as far as 46°S, suggesting that enhanced meridional overturning circulation may have been responsible for more southerly penetration of North Atlantic Deep Water (NADW). However, deep temperature proxies are not diagnostic of water mass, and some coupled model simulations predict transient decreases in NADW production in the 21st century, presenting a contrasting picture of future climate. We present a new multi-proxy synthesis of Atlantic deep ocean circulation during the PRISM interval, using the neodymium isotopic composition (ɛNd) of fossil fish teeth as a proxy for water mass source and the δ13C of benthic foraminifera as a proxy for water mass age. This reconstruction utilizes both new and previously published data from 11 DSDP and ODP sites in the North Atlantic (Site 610) and along depth transects from equatorial Ceara Rise, southern mid-latitude Walvis Ridge, and south Atlantic Meteor Rise/Agulhas Ridge. Published data from ferromanganese crusts constrain Pliocene Antarctic deep waters at ~ ɛNd = -8, distinct from the less radiogenic ɛNd = -11.5 that characterizes Pliocene northern component water (NCW). These values fingerprint northern and southern sources throughout the Atlantic basin. Pliocene fish teeth from Site 610 (2400 m water depth) and from four Ceara Rise sites (3000-4300 m) preserve distinctly North Atlantic ɛNd. When averaged across the PRISM interval, mean values for these five sites range from ɛNd = -10.97 to -10.25, and the Pliocene depth transect closely mirrors the structure of the modern column, indicating

Neodymium-yttrium aluminum garnet laser versus pulsed dye laser in erythemato-telangiectatic rosacea: comparison of clinical efficacy and effect on cutaneous substance (P) expression.

PubMed

Salem, Samar Abdallah M; Abdel Fattah, Nermeen S A; Tantawy, Samah M A; El-Badawy, Nafissa M A; Abd El-Aziz, Yasser A

2013-09-01

Different laser systems are reported to be effective in treatment of telangiectasia and erythema, but comparative studies on 1064-nm neodymium-yttrium aluminum garnet (Nd-YAG) laser and pulsed dye laser (PDL) in treatment of erythemato-telangiectatic rosacea are lacking. Substance (P) is implicated in rosacea pathogenesis. To compare the effect of Nd-YAG laser and PDL on erythemato-telangiectatic rosacea, both clinically and immunohistochemically on cutaneous substance (P) expression. This split-face comparative study included 15 patients with erythemato-telangiectatic rosacea treated on the right side with Nd-YAG laser and on the left side with PDL: three sessions, 4 weeks apart. Evaluation of the patients was done using erythema and telangiectasia grading scores, patient's self-assessment, physicians' clinical assessment of the patient, and immunohistochemical assessment of substance (P). One month after the three laser sessions, excellent response was achieved in 73.3% of patients after Nd-YAG and in 53.3% of patients after PDL with significantly lower substance (P) concentration after Nd-YAG laser than after PDL. Positive correlations were found between the decrease in erythema and telangiectasia grading scores and the decrease in substance (P) concentration. The use of Nd-YAG laser and PDL appears to be safe and effective measures in treatment of erythemato-telangiectatic rosacea. Both types of laser decrease the concentration of substance (P) in the skin. This effect is more pronounced with Nd-YAG laser. © 2013 Wiley Periodicals, Inc.

Sporicidal Effects of Iodine-oxide Thermite Reaction Products

NASA Astrophysics Data System (ADS)

Russell, Rod; Bless, Stephan; Blinkova, Alexandra; Chen, Tiffany; InstituteAdvanced Tehnology Collaboration; Dept of Molecular Genetics; Microbiology-UT Austin Collaboration; Chemistry; Biochemistry-UT Austin Collaboration

2011-06-01

Iodine pentoxide-aluminum thermite reactions have been driven by impacts at 1000 m/s on steel plates 3 mm or thicker. The activation energy of this material reaction is 197 J/g. The reactivity is increased by reducing grain size. This reaction releases iodine gas that is known to be a sporicide. In order to test the impact reactions for sporicidal effects, reactions took place in closed chambers containing dried Bacillus subtilis spores. The reduction in colony-forming units was dependent on the exposure time; long exposure times resulted in a 105 decrease in germination rate. This was shown to be due to the gas exposure and not the heat or turbulence. Sporicidal effectiveness was increased by adding neodymium and saran resin. The sporicidal effect is very dependent on exposure time, ranging from about 90% kill for times on the order of a second to 99.99% for one-hour times.

Comparison of hair removal efficacy and side effect of neodymium:Yttrium-aluminum-garnet laser and intense pulsed light systems (18-month follow-up).

PubMed

Szima, Georgina Zita; Janka, Eszter Anna; Kovács, Anikó; Bortély, Blanka; Bodnár, Edina; Sawhney, Irina; Szabó, Éva; Remenyik, Éva

2017-06-01

Photothermal destruction of hair shaft melanin with intense pulsed light (IPL) and neodymium:yttrium-aluminum-garnet (Nd:YAG) laser has become an effective treatment of hair removal. Our aim was to compare efficacy, satisfactory levels, safety, and side effects of Nd:YAG and IPL in hair reduction. This was a prospective randomized intrapatient, right-left, assessor-blinded comparison of Nd:YAG vs IPL. There were 38 volunteers recruited. Seven sessions were performed. Hair count, efficacy, and side effects were compared before and after each treatment and 6 months after the last treatment. In respect of 12 volunteers, we have examined the reduction in hair after 18 months. Initially, there was no significant difference between the numbers of hair follicles. There was significant hair reduction after each treatment on the Nd:YAG-treated side. The hair reduction became significant after the third treatment with IPL. Comparison of the efficacy of the two devices on each visits showed no significant difference. There was statistically lower pain score on the IPL-treated side and statistically higher erythema, burning sensation, and edema on the Nd:YAG-treated side. Statistically lower side effect score was observed on the IPL-treated side. Eight months after the last treatment, there was significant hair reduction both on the Nd:YAG and on the IPL-treated side, and there was no difference between the efficacy. The patient satisfaction scores were higher with the IPL. Unwanted hair can be reduced by both systems safely and effectively; however, IPL has less side effects and higher satisfaction scores. © 2017 Wiley Periodicals, Inc.

Combined vitamin C sonophoresis and neodymium-doped yttrium aluminum garnet (NdYAG) laser for facial hyperpigmentation: An outcome observation study in Asian patients.

PubMed

Chen, Yu-Tsung; Chang, Chang-Cheng; Hsu, Cherng-Ru; Shen, Jen-Hsiang; Shih, Chao-Jen; Lin, Bor-Shyh

2016-01-01

The neodymium-doped yttrium aluminum garnet (NdYAG) laser therapy has been a popular technique for facial rejuvenation but certain adverse effects like post-inflammatory hyperpigmentation are issues of concern to Asian patients. To assess the outcome following combined treatment with vitamin C sonophoresis and NdYAG laser, in selected cases of facial hyperpigmentation. Twenty three women with dyschromia or melasma who had undergone five sessions of Q-switched NdYAG laser therapy followed by transdermal delivery of vitamin C via sonophoresis were selected after a retrospective review of case records. The objective and subjective clinical outcomes and the side effects, including erythema, scaling, pruritus, dryness and post-inflammatory hyperpigmentation were evaluated. In both objective or subjective outcomes, 91.3% (21/23) of the patients showed an excellent or better outcome, while 8.7% (2/23) showed no change. A majority of the patients (73.9%, 17/23) experienced no post-inflammatory hyperpigmentation or had slight post-inflammatory hyperpigmentation which quickly resolved within 1 week. Only one (4.3%) patient had extreme post-inflammatory hyperpigmentation which lasted for over a month. This was a retrospective study without a control group; a comparative study with a control group (patients treated with the laser alone, without vitamin C sonopheresis) is needed to determine the difference in the outcome. The use of vitamin C sonophoresis along with NdYAG laser may reduce the incidence of adverse effects in Asian patients. Patients experienced obvious improvement in hyperpigmentation and had lower chances of experiencing extreme or severe post-inflammatory hyperpigmentation.

Effects of neodymium-yttrium-aluminum garnet (Nd:YAG) pulsed high-intensity laser therapy on full thickness wound healing in an experimental animal model.

PubMed

Hong, Seung Eun; Hong, Mi Ki; Kang, So Ra; Young Park, Bo

2016-12-01

Wound healing can be aided by the use of low- and medium-intensity lasers. The use of pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) high-intensity laser therapy (HILT) with a 1064-nm wavelength laser provides deeper and more efficient penetration into tissue as it is being less absorbed by chromophores in tissue, e.g., hemoglobin, melanin, and water, thereby enhancing the wound-healing process. In this study, we examined the effect of HILT on wound healing with a Q-switched pulsed Nd:YAG laser in an animal model. Sixty SKH1 hairless male mice (seven weeks old) were randomly divided into four groups according to the amount of laser fluence: control, group 1 (0.8 J/cm 2 ), group 2 (1.6 J/cm 2 ), and group 3 (2.0 J/cm 2 ). Laser treatment was provided to groups 1, 2, and 3 with a 1064-nm Q-switched Nd:YAG laser. Histological analysis was performed with hematoxylin and eosin staining, Masson's Trichrome staining, and Ki-67 staining. Statistically significant increases in the accumulation of collagen fibers, thickness of granulation tissue, and numbers of fibroblasts were observed in group 2 (treated with 1.6 J/cm 2 ) as compared with the control (no laser treatment), group 1 (treated with 0.8 J/cm 2 ), and group 3 (treated with 2.0 J/cm 2 ). Nd:YAG HILT stimulated fibroblast proliferation and increased extracellular matrix production. We expect that this therapy could accelerate the wound-healing process.

Perpendicular magnetic anisotropy in amorphous NdxCo1 -x thin films studied by x-ray magnetic circular dichroism

NASA Astrophysics Data System (ADS)

Cid, R.; Alameda, J. M.; Valvidares, S. M.; Cezar, J. C.; Bencok, P.; Brookes, N. B.; Díaz, J.

2017-06-01

The origin of perpendicular magnetic anisotropy (PMA) in amorphous NdxCo1 -x thin films is investigated using x-ray magnetic circular dichroism (XMCD) spectroscopy at the Co L2 ,3 and Nd M4 ,5 edges. The magnetic orbital and spin moments of the 3 d cobalt and 4 f neodymium electrons were measured as a function of the magnetic field orientation, neodymium concentration, and temperature. In all the studied samples, the magnetic anisotropy of the neodymium subnetwork is always oriented perpendicular to the plane, whereas the anisotropy of the orbital moment of cobalt is in the basal plane. The ratio Lz/Sz of the neodymium 4 f orbitals changes with the sample orientation angle, being higher and closer to the atomic expected value at normal orientation and smaller at grazing angles. This result is well explained by assuming that the 4 f orbital is distorted by the effect of an anisotropic crystal field when it is magnetized along its hard axis, clearly indicating that the 4 f states are not rotationally invariant. The magnetic anisotropy energy associated to the neodymium subnetwork should be proportional to this distortion, which we demonstrate is accessible by applying the XMCD sum rules for the spin and intensity at the Nd M4 ,5 edges. The analysis unveils a significant portion of neodymium atoms magnetically uncoupled to cobalt, i.e., paramagnetic, confirming the inhomogeneity of the films and the presence of a highly disordered neodymium rich phase already detected by extended x-ray-absorption fine structure (EXAFS) spectroscopy. The presence of these inhomogeneities is inherent to the evaporation preparation method when the chosen concentration in the alloy is far from its eutectic concentrations. An interesting consequence of the particular way in which cobalt and neodymium segregates in this system is the enhancement of the cobalt spin moment which reaches 1.95 μB in the sample with the largest segregation.

Isomorphous rare-earth tris[bis(2,6-diisopropylphenyl) phosphate] complexes and their catalytic properties in 1,3-diene polymerization and in the inhibited oxidation of polydimethylsiloxane.

PubMed

Minyaev, Mikhail E; Tavtorkin, Alexander N; Korchagina, Sof'ya A; Bondarenko, Galina N; Churakov, Andrei V; Nifant'ev, Ilya E

2018-05-01

Crystals of mononuclear tris[bis(2,6-diisopropylphenyl) phosphato-κO]pentakis(methanol-κO)lanthanide methanol monosolvates of lanthanum, [La(C 24 H 34 O 4 P) 3 (CH 3 OH) 5 ]·CH 3 OH, (1), cerium, [Ce(C 24 H 34 O 4 P) 3 (CH 3 OH) 5 ]·CH 3 OH, (2), and neodymium, [Nd(C 24 H 34 O 4 P) 3 (CH 3 OH) 5 ]·CH 3 OH, (3), have been obtained by reactions between LnCl 3 (H 2 O) n (n = 6 or 7) and lithium bis(2,6-diisopropylphenyl) phosphate in a 1:3 molar ratio in methanol media. Compounds (1)-(3) crystallize in the monoclinic P2 1 /c space group and have isomorphous crystal structures. All three bis(2,6-diisopropylphenyl) phosphate ligands display a κO-monodentate coordination mode. The coordination number of the metal atom is 8. Each [Ln{O 2 P(O-2,6- i Pr 2 C 6 H 3 ) 2 } 3 (CH 3 OH) 5 ] molecular unit exhibits four intramolecular O-H...O hydrogen bonds, forming six-membered rings. The unit forms two intermolecular O-H...O hydrogen bonds with one noncoordinating methanol molecule. All six hydroxy H atoms are involved in hydrogen bonding within the [Ln{O 2 P(O-2,6- i Pr 2 C 6 H 3 ) 2 } 3 (CH 3 OH) 5 ]·CH 3 OH unit. This, along with the high steric hindrance induced by the three bulky diaryl phosphate ligands, prevents the formation of a hydrogen-bond network. Complexes (1)-(3) exhibit disorder of two of the isopropyl groups of the phosphate ligands. The cerium compound (2) demonstrates an essential catalytic inhibition in the thermal decomposition of polydimethylsiloxane in air at 573 K. Catalytic systems based on the neodymium complex tris[bis(2,6-diisopropylphenyl) phosphato-κO]neodymium, (3'), which was obtained as a dry powder of (3) upon removal of methanol, display a high catalytic activity in isoprene and butadiene polymerization.

Oxidative shielding or oxidative stress?

PubMed

Naviaux, Robert K

2012-09-01

In this review I report evidence that the mainstream field of oxidative damage biology has been running fast in the wrong direction for more than 50 years. Reactive oxygen species (ROS) and chronic oxidative changes in membrane lipids and proteins found in many chronic diseases are not the result of accidental damage. Instead, these changes are the result of a highly evolved, stereotyped, and protein-catalyzed "oxidative shielding" response that all eukaryotes adopt when placed in a chemically or microbially hostile environment. The machinery of oxidative shielding evolved from pathways of innate immunity designed to protect the cell from attack and limit the spread of infection. Both oxidative and reductive stress trigger oxidative shielding. In the cases in which it has been studied explicitly, functional and metabolic defects occur in the cell before the increase in ROS and oxidative changes. ROS are the response to disease, not the cause. Therefore, it is not the oxidative changes that should be targeted for therapy, but rather the metabolic conditions that create them. This fresh perspective is relevant to diseases that range from autism, type 1 diabetes, type 2 diabetes, cancer, heart disease, schizophrenia, Parkinson's disease, and Alzheimer disease. Research efforts need to be redirected. Oxidative shielding is protective and is a misguided target for therapy. Identification of the causal chemistry and environmental factors that trigger innate immunity and metabolic memory that initiate and sustain oxidative shielding is paramount for human health.

Neodymium: yttrium-aluminum-garnet long impulse laser for the elimination of superfluous hair: experiences and considerations from 3 years of activity.

PubMed

Ferraro, G A; Perrotta, A; Rossano, F; D'Andrea, F

2004-01-01

This study examined the results obtained with a modern apparatus for laser hair removal (neodymium: yttrium-aluminum-garnet [Nd:YAG] laser at long impulses with a wave-length of 1,064 nm; Q-switched laser) over a follow-up period of 3 years. A large heterogeneous group of 480 patients was taken into consideration. These patients were treated according to a standard protocol with monthly checkups and a personalized protocol at deferred appointments. The results, discovered by means of the most objective procedure possible, were retrieved and put into a graph showing two different curves for the repopulation of hair. In their clinical travels, the authors observed an average variable regrowth of 40% to 65%, allowing them to affirm that laser hair removal using Nd:YAG at long impulses is decisively efficient in obtaining long-term results. The use of a protocol (denominated "prolonged monthly checkup") with laser sessions at ever-decreasing periods permits, among other things, more outstanding and advantageous results for the patient. Thanks to more efficiently synchronized phases of the biologic hair cycle, this shortens and moves the telegenic phases closer and also renders the anagenic phases (those in which the selective photoermolysis on the pilipheric follicle proves to be efficient) more efficient. Personalization of the treatment relative to the monthly health checkup sessions is of fundamental importance to the scope of obtaining the best results in terms of cost-benefit rate, provided submassimal fluxes are (i.e., those well-tolerated by the patient) used. All this allows hair removal that is not definitive, but which becomes progressively permanent (i.e., characterized by ever-growing periods of lack of hair sustained by sporadic maintenance laser sessions based on the individual's necessity).

Quasi-isentropic Compression of Iron and Magnesium Oxide to 3 Mbar at the Omega Laser Facility

NASA Astrophysics Data System (ADS)

Wang, J.; Smith, R. F.; Coppari, F.; Eggert, J. H.; Boehly, T.; Collins, G.; Duffy, T. S.

2011-12-01

Developing a high-pressure, modest temperature ramp compression drive permits exploration of new regions of thermodynamic space, inaccessible through traditional methods of shock or static compression, and of particular relevance to material conditions found in planetary interiors both within and outside our solar system. Ramp compression is a developing technique that allows materials to be compressed along a quasi-isentropic path and provides the ability to study materials in the solid state to higher pressures than can be achieved with diamond anvil cell or shock wave methods. Iron and magnesium oxide are geologically important materials each representative of one of the two major interior regions (core and mantle) of terrestrial planets. An experimental platform for ramp loading of iron (Fe) and magnesium oxide (MgO), has been established and tested in experiments at the Omega Laser Facility, University of Rochester. Omega is a 60-beam ultraviolet (352 nm) neodymium glass laser which is capable of delivery kilojoules of energy in ~10 ns pulses onto targets of a few mm in dimension. In the current experiments, we used a composite ramped laser pulse involving typically 15 beams with total energy of 2.6-3.3 kJ. The laser beams were used to launch spatially planar ramp compression waves into Fe and MgO targets. Each target had four steps that were approximately 5-7 μm thick. Detection of the ramp wave arrival and its velocity at the free surface of each step was made using a VISAR velocity interferometer. Through the use of Lagrangian analysis on the measured wave profiles, stress-density states in iron and magnesium oxide have been determined to pressures of 291 GPa and 260 GPa respectively. For Fe, the α-ɛ transition of iron is overdriven by an initial shock pulse of ~90.1 GPa followed by ramp compression to the peak pressure. The results will be compared with shock compression and diamond anvil cell data for both materials.

The Enzymatic Oxidation of Graphene Oxide

PubMed Central

Kotchey, Gregg P.; Allen, Brett L.; Vedala, Harindra; Yanamala, Naveena; Kapralov, Alexander A.; Tyurina, Yulia Y.; Klein-Seetharaman, Judith; Kagan, Valerian E.; Star, Alexander

2011-01-01

Two-dimensional graphitic carbon is a new material with many emerging applications, and studying its chemical properties is an important goal. Here, we reported a new phenomenon – the enzymatic oxidation of a single layer of graphitic carbon by horseradish peroxidase (HRP). In the presence of low concentrations of hydrogen peroxide (~40 µM), HRP catalyzed the oxidation of graphene oxide, which resulted in the formation of holes on its basal plane. During the same period of analysis, HRP failed to oxidize chemically reduced graphene oxide (RGO). The enzymatic oxidation was characterized by Raman, UV-Vis, EPR and FT-IR spectroscopy, TEM, AFM, SDS-PAGE, and GC-MS. Computational docking studies indicated that HRP was preferentially bound to the basal plane rather than the edge for both graphene oxide and RGO. Due to the more dynamic nature of HRP on graphene oxide, the heme active site of HRP was in closer proximity to graphene oxide compared to RGO, thereby facilitating the oxidation of the basal plane of graphene oxide. We also studied the electronic properties of the reduced intermediate product, holey reduced graphene oxide (hRGO), using field-effect transistor (FET) measurements. While RGO exhibited a V-shaped transfer characteristic similar to a single layer of graphene that was attributed to its zero band gap, hRGO demonstrated a p-type semiconducting behavior with a positive shift in the Dirac points. This p-type behavior rendered hRGO, which can be conceptualized as interconnected graphene nanoribbons, as a potentially attractive material for FET sensors. PMID:21344859

Measurement of the distribution coefficient of neodymium in cubic ZrO 2

NASA Astrophysics Data System (ADS)

Römer, H.; Luther, K.-D.; Assmus, W.

1993-05-01

The incorporation of solute elements into single crystals has been examined for many years. In this paper we investigate the distribution coefficient of Nd 2O 3 in cubic stabilized zirconiumdioxide crystals. The distribution coefficient is measured as a function of the growth velocity. The validity of the Burton-Prim-Slichter theory [J.A. Burton, R.C. Prim and W.P. Slichter, J. Chem. Phys. 21 (1953) 1987] for the system zirconium dioxide/yttrium oxide is confirmed by the experimental results. The value for the equilibrium distribution coefficient is evaluated as k0 = 0.426.

Noise Spectroscopy in Strongly Correlated Oxides

NASA Astrophysics Data System (ADS)

Alsaqqa, Ali M.

Strongly correlated materials are an interesting class of materials, thanks to the novel electronic and magnetic phenomena they exhibit as a result of the interplay of various degrees of freedom. This gives rise to an array of potential applications, from Mott-FET to magnetic storage. Many experimental probes have been used to study phase transitions in strongly correlated oxides. Among these, resistance noise spectroscopy, together with conventional transport measurements, provides a unique viewpoint to understand the microscopic dynamics near the phase transitions in these oxides. In this thesis, utilizing noise spectroscopy and transport measurements, four different strongly correlated materials were studied: (1) neodymium nickel oxide (NdNiO 3) ultrathin films, (2) vanadium dioxide (VO2) microribbons, (3) copper vanadium bronze (CuxV2O 5) microribbons and (4) niobium triselenide (NbSe3) microribbons. Ultra thin films of rare-earth nickelates exhibit several temperature-driven phase transitions. In this thesis, we studied the metal-insulator and Neel transitions in a series of NdNiO3 films with different lattice mismatches. Upon colling down, the metal-insulator phase transition is accompanied by a structural (orthorohombic to monoclinic) and magnetic (paramagnetic to antiferromagnetic) transitions as well, making the problem more interesting and complex at the same time. The noise is of the 1/f type and is Gaussian in the high temperature phase, however deviations are seen in the low temperature phases. Below the metal-insulator transition, noise magnitude increases by orders of magnitude: a sign of inhomogeneous electrical conduction as result of phase separation. This is further assured by the non-Gaussian noise signature. At very low temperatures (T < 50 K), the noise behavior switches between Gaussian and non-Gaussian over several hours, possibly arising from dynamically competing ground states. VO2 is one of the most widely studied strongly correlated

Stabilized tin-oxide-based oxidation/reduction catalysts

NASA Technical Reports Server (NTRS)

Watkins, Anthony Neal (Inventor); Oglesby, Donald M. (Inventor); Gulati, Suresh T. (Inventor); Summers, Jerry C. (Inventor); Schryer, David R. (Inventor); Davis, Patricia P. (Inventor); Leighty, Bradley D. (Inventor); Jordan, Jeffrey D. (Inventor); Schryer, Jacqueline L. (Inventor)

2008-01-01

The invention described herein involves a novel approach to the production of oxidation/reduction catalytic systems. The present invention serves to stabilize the tin oxide reducible metal-oxide coating by co-incorporating at least another metal-oxide species, such as zirconium. In one embodiment, a third metal-oxide species is incorporated, selected from the group consisting of cerium, lanthanum, hafnium, and ruthenium. The incorporation of the additional metal oxide components serves to stabilize the active tin-oxide layer in the catalytic process during high-temperature operation in a reducing environment (e.g., automobile exhaust). Moreover, the additional metal oxides are active components due to their oxygen-retention capabilities. Together, these features provide a mechanism to extend the range of operation of the tin-oxide-based catalyst system for automotive applications, while maintaining the existing advantages.

The enzymatic oxidation of graphene oxide.

PubMed

Kotchey, Gregg P; Allen, Brett L; Vedala, Harindra; Yanamala, Naveena; Kapralov, Alexander A; Tyurina, Yulia Y; Klein-Seetharaman, Judith; Kagan, Valerian E; Star, Alexander

2011-03-22

Two-dimensional graphitic carbon is a new material with many emerging applications, and studying its chemical properties is an important goal. Here, we reported a new phenomenon--the enzymatic oxidation of a single layer of graphitic carbon by horseradish peroxidase (HRP). In the presence of low concentrations of hydrogen peroxide (∼40 μM), HRP catalyzed the oxidation of graphene oxide, which resulted in the formation of holes on its basal plane. During the same period of analysis, HRP failed to oxidize chemically reduced graphene oxide (RGO). The enzymatic oxidation was characterized by Raman, ultraviolet-visible, electron paramagnetic resonance, Fourier transform infrared spectroscopy, transmission electron microscopy, atomic force microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and gas chromatography-mass spectrometry. Computational docking studies indicated that HRP was preferentially bound to the basal plane rather than the edge for both graphene oxide and RGO. Owing to the more dynamic nature of HRP on graphene oxide, the heme active site of HRP was in closer proximity to graphene oxide compared to RGO, thereby facilitating the oxidation of the basal plane of graphene oxide. We also studied the electronic properties of the reduced intermediate product, holey reduced graphene oxide (hRGO), using field-effect transistor (FET) measurements. While RGO exhibited a V-shaped transfer characteristic similar to a single layer of graphene that was attributed to its zero band gap, hRGO demonstrated a p-type semiconducting behavior with a positive shift in the Dirac points. This p-type behavior rendered hRGO, which can be conceptualized as interconnected graphene nanoribbons, as a potentially attractive material for FET sensors.

In-situ and self-distributed: A new understanding on catalyzed thermal decomposition process of ammonium perchlorate over Nd{sub 2}O{sub 3}

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

Zou, Min, E-mail: zoumin3362765@163.com; Wang, Xin, E-mail: wangx@mail.njust.edu.cn; Jiang, Xiaohong, E-mail: jxh0668@sina.com

2014-05-01

Catalyzed thermal decomposition process of ammonium perchlorate (AP) over neodymium oxide (Nd{sub 2}O{sub 3}) was investigated. Catalytic performances of nanometer-sized Nd{sub 2}O{sub 3} and micrometer-sized Nd{sub 2}O{sub 3} were evaluated by differential scanning calorimetry (DSC). In contrast to universal concepts, catalysts in different sizes have nearly similar catalytic activities. Based on structural and morphological variation of the catalysts during the reaction, combined with mass spectrum analyses and studies of unmixed style, a new understanding of this catalytic process was proposed. We believed that the newly formed chloride neodymium oxide (NdOCl) was the real catalytic species in the overall thermal decompositionmore » of AP over Nd{sub 2}O{sub 3}. Meanwhile, it was the “self-distributed” procedure which occurred within the reaction that also worked for the improvement of overall catalytic activities. This work is of great value in understanding the roles of micrometer-sized catalysts used in heterogeneous reactions, especially the solid–solid reactions which could generate a large quantity of gaseous species. - Graphical abstract: In-situ and self-distributed reaction process in thermal decomposition of AP catalyzed by Nd{sub 2}O{sub 3}. - Highlights: • Micro- and nano-Nd{sub 2}O{sub 3} for catalytic thermal decomposition of AP. • No essential differences on their catalytic performances. • Structural and morphological variation of catalysts digs out catalytic mechanism. • This catalytic process is “in-situ and self-distributed” one.« less

Nitric oxide scavengers differentially inhibit ammonia oxidation in ammonia-oxidizing archaea and bacteria.

PubMed

Sauder, Laura A; Ross, Ashley A; Neufeld, Josh D

2016-04-01

Differential inhibitors are important for measuring the relative contributions of microbial groups, such as ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), to biogeochemical processes in environmental samples. In particular, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) represents a nitric oxide scavenger used for the specific inhibition of AOA, implicating nitric oxide as an intermediate of thaumarchaeotal ammonia oxidation. This study investigated four alternative nitric oxide scavengers for their ability to differentially inhibit AOA and AOB in comparison to PTIO. Caffeic acid, curcumin, methylene blue hydrate and trolox were tested onNitrosopumilus maritimus, two unpublished AOA representatives (AOA-6f and AOA-G6) as well as the AOB representative Nitrosomonas europaea All four scavengers inhibited ammonia oxidation by AOA at lower concentrations than for AOB. In particular, differential inhibition of AOA and AOB by caffeic acid (100 μM) and methylene blue hydrate (3 μM) was comparable to carboxy-PTIO (100 μM) in pure and enrichment culture incubations. However, when added to aquarium sponge biofilm microcosms, both scavengers were unable to inhibit ammonia oxidation consistently, likely due to degradation of the inhibitors themselves. This study provides evidence that a variety of nitric oxide scavengers result in differential inhibition of ammonia oxidation in AOA and AOB, and provides support to the proposed role of nitric oxide as a key intermediate in the thaumarchaeotal ammonia oxidation pathway. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Comparative Study of Diode Laser Versus Neodymium-Yttrium Aluminum: Garnet Laser Versus Intense Pulsed Light for the Treatment of Hirsutism.

PubMed

Puri, Neerja

2015-01-01

Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminum - garnet (Nd: YAG) laser and intense pulsed light (IPL) on 30 female patients of hirsutism. Thirty female patients with hirsutism were selected for a randomised controlled study. The patients were divided into three groups of 10 patients each. In group I patients diode laser was used, in group II patients long pulsed Nd: YAG laser was used and in group III, IPL was used. The patients were evaluated and result graded according to a 4-point scale as excellent, >75% reduction; good, 50-75% reduction; fair; 25-50% reduction; and poor, <25% reduction in hair density. It was seen that the percentage of hair reduction after two sessions of treatment was maximum (40%) in the diode laser group, followed by 35% hair reduction in the Nd: Yag laser group and 10% hair reduction in the IPL group. The percentage of hair reduction after four sessions of treatment was maximum (64%) in the diode laser group, followed by 62% hair reduction in the Nd: Yag laser group and 48% hair reduction in the IPL group. The percentage of hair reduction after eight sessions of treatment was maximum (92%) in the diode laser group, followed by 90% hair reduction in the Nd: YAG group and 70% hair reduction in the IPL group. To conclude for the Indian skin with dark hairs, the diode laser still stands the test of time. But, since the diode laser has a narrow margin of safety, proper pre and post-procedure cooling is recommended. Although, the side effects of Nd: YAG laser are less as compared to the diode laser, it is less efficacious as compared to the diode laser.

Oxidation kinetics of Si and SiGe by dry rapid thermal oxidation, in-situ steam generation oxidation and dry furnace oxidation

NASA Astrophysics Data System (ADS)

Rozé, Fabien; Gourhant, Olivier; Blanquet, Elisabeth; Bertin, François; Juhel, Marc; Abbate, Francesco; Pribat, Clément; Duru, Romain

2017-06-01

The fabrication of ultrathin compressively strained SiGe-On-Insulator layers by the condensation technique is likely a key milestone towards low-power and high performances FD-SOI logic devices. However, the SiGe condensation technique still requires challenges to be solved for an optimized use in an industrial environment. SiGe oxidation kinetics, upon which the condensation technique is founded, has still not reached a consensus in spite of various studies which gave insights into the matter. This paper aims to bridge the gaps between these studies by covering various oxidation processes relevant to today's technological needs with a new and quantitative analysis methodology. We thus address oxidation kinetics of SiGe with three Ge concentrations (0%, 10%, and 30%) by means of dry rapid thermal oxidation, in-situ steam generation oxidation, and dry furnace oxidation. Oxide thicknesses in the 50 Å to 150 Å range grown with oxidation temperatures between 850 and 1100 °C were targeted. The present work shows first that for all investigated processes, oxidation follows a parabolic regime even for thin oxides, which indicates a diffusion-limited oxidation regime. We also observe that, for all investigated processes, the SiGe oxidation rate is systematically higher than that of Si. The amplitude of the variation of oxidation kinetics of SiGe with respect to Si is found to be strongly dependent on the process type. Second, a new quantitative analysis methodology of oxidation kinetics is introduced. This methodology allows us to highlight the dependence of oxidation kinetics on the Ge concentration at the oxidation interface, which is modulated by the pile-up mechanism. Our results show that the oxidation rate increases with the Ge concentration at the oxidation interface.

Powerful Oxidizing Agents for the Oxidative Deintercalation of Lithium from Transition Metal Oxides

DTIC Science & Technology

1989-08-16

22217 11 TITLE dnrcluae Sec’.r/ 2 ’als.rit,catC Powerful Oxidizing Agents for the Oxidative Deintercalation of Lithium from Transition Metal Oxides...0 d dlentity by block number) FIELD GROUP SUB GROUP Oxidizing Agents, Lithium Oxides I - Deintercalation 19 AbS*RA?, trne on-tsxes~e it necessary...anid enit’y oy 010ck .1Uf~oer. N02+ andMoF6 are shown to be powerful oxidizing agents for the deintercalation of lithium from Li~oO2 an 62Ct . The

10 CFR Appendix L to Part 110 - Illustrative List of Byproduct Materials Under NRC Export/Import Licensing Authority a

Code of Federal Regulations, 2011 CFR

2011-01-01

...) Neodymium 147 (Nd 147) Neodymium 149 (Nd 149) Neptunium 235 (Np 235) Neptunium 237 (Np 237) Nickel 59 (Ni 59) Nickel 63 (Ni 63) Nickel 65 (Ni 65) Niobium 93m (Nb 93m) Niobium 94 (Nb 94) Niobium 95 (Nb 95) Niobium 97...

Rare earth gas laser

DOEpatents

Krupke, W.F.

1975-10-31

A high energy gas laser with light output in the infrared or visible region of the spectrum is described. Laser action is obtained by generating vapors of rare earth halides, particularly neodymium iodide or, to a lesser extent, neodymium bromide, and disposing the rare earth vapor medium in a resonant cavity at elevated temperatures; e.g., approximately 1200/sup 0/ to 1400/sup 0/K. A particularly preferred gaseous medium is one involving a complex of aluminum chloride and neodymium chloride, which exhibits tremendously enhanced vapor pressure compared to the rare earth halides per se, and provides comparable increases in stored energy densities.

Impacts of neodymium on structural, spectral and dielectric properties of LiNi0.5Fe2O4 nanocrystalline ferrites fabricated via micro-emulsion technique

NASA Astrophysics Data System (ADS)

Gilani, Zaheer Abbas; Warsi, Muhammad Farooq; Khan, Muhammad Azhar; Shakir, Imran; Shahid, Muhammad; Anjum, Muhammad Naeem

2015-09-01

Soft ferrites are technologically advanced smart materials and their properties can be tailored by controlling the chemical composition and judicial choice of the metal elements. In this article we discussed the effect of rare earth neodymium (Nd3+) on various properties of LiNi0.5NdxFe2-xO4 spinel ferrites. These ferrites have been synthesized by facile micro-emulsion route and characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), a.c. electrical conductivity and thermal analysis. The influence of Nd3+ doping on structural and electrical parameters has been investigated. XRD analysis revealed the formation of single cubic spinel structure for x≤0.07. Few traces of secondary phase (NdFeO3) were found for x≥0.105. The secondary phase induced owing to the solubility limit of Nd3+ cations in these ferrites. The lattice parameter (a) and crystallite size (D) both exhibit non-linear relation. The values of "a" and "D" were found in the range 8.322-8.329 Å and 25-32 nm respectively. These variations were attributed to the larger ionic radius of Nd3+ cations as compared to the host cations and lattice strain produced in these ferrites. The dielectric parameters were studied in the range 1 MHz to 3 GHz and these parameters were damped by Nd3+ incorporation and also by increasing the frequency. The reduced dielectric parameters observed in wide frequency range proposed that these nanocrystalline ferrites are potential candidates for fabricating the devices which are required to operate at GHz frequencies.

Silver(II) Oxide or Silver(I,III) Oxide?

ERIC Educational Resources Information Center

Tudela, David

2008-01-01

The often called silver peroxide and silver(II) oxide, AgO or Ag[subscript 2]O[subscript 2], is actually a mixed oxidation state silver(I,III) oxide. A thermochemical cycle, with lattice energies calculated within the "volume-based" thermodynamic approach, explain why the silver(I,III) oxide is more stable than the hypothetical silver(II) oxide.…

Solid oxide fuel cells fueled with reducible oxides

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

Chuang, Steven S.; Fan, Liang Shih

A direct-electrochemical-oxidation fuel cell for generating electrical energy includes a cathode provided with an electrochemical-reduction catalyst that promotes formation of oxygen ions from an oxygen-containing source at the cathode, a solid-state reduced metal, a solid-state anode provided with an electrochemical-oxidation catalyst that promotes direct electrochemical oxidation of the solid-state reduced metal in the presence of the oxygen ions to produce electrical energy, and an electrolyte disposed to transmit the oxygen ions from the cathode to the solid-state anode. A method of operating a solid oxide fuel cell includes providing a direct-electrochemical-oxidation fuel cell comprising a solid-state reduced metal, oxidizing themore » solid-state reduced metal in the presence of oxygen ions through direct-electrochemical-oxidation to obtain a solid-state reducible metal oxide, and reducing the solid-state reducible metal oxide to obtain the solid-state reduced metal.« less

Hysteresis-free high rate reactive sputtering of niobium oxide, tantalum oxide, and aluminum oxide

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

Särhammar, Erik, E-mail: erik.sarhammar@angstrom.uu.se; Berg, Sören; Nyberg, Tomas

2014-07-01

This work reports on experimental studies of reactive sputtering from targets consisting of a metal and its oxide. The composition of the targets varied from pure metal to pure oxide of Al, Ta, and Nb. This combines features from both the metal target and oxide target in reactive sputtering. If a certain relation between the metal and oxide parts is chosen, it may be possible to obtain a high deposition rate, due to the metal part, and a hysteresis-free process, due to the oxide part. The aim of this work is to quantify the achievable boost in oxide deposition ratemore » from a hysteresis-free process by using a target consisting of segments of a metal and its oxide. Such an increase has been previously demonstrated for Ti using a homogeneous substoichiometric target. The achievable gain in deposition rate depends on transformation mechanisms from oxide to suboxides due to preferential sputtering of oxygen. Such mechanisms are different for different materials and the achievable gain is therefore material dependent. For the investigated materials, the authors have demonstrated oxide deposition rates that are 1.5–10 times higher than what is possible from metal targets in compound mode. However, although the principle is demonstrated for oxides of Al, Ta, and Nb, a similar behavior is expected for most oxides.« less

Highly oxidized graphene oxide and methods for production thereof

DOEpatents

Tour, James M.; Kosynkin, Dmitry V.

2016-08-30

A highly oxidized form of graphene oxide and methods for production thereof are described in various embodiments of the present disclosure. In general, the methods include mixing a graphite source with a solution containing at least one oxidant and at least one protecting agent and then oxidizing the graphite source with the at least one oxidant in the presence of the at least one protecting agent to form the graphene oxide. Graphene oxide synthesized by the presently described methods is of a high structural quality that is more oxidized and maintains a higher proportion of aromatic rings and aromatic domains than does graphene oxide prepared in the absence of at least one protecting agent. Methods for reduction of graphene oxide into chemically converted graphene are also disclosed herein. The chemically converted graphene of the present disclosure is significantly more electrically conductive than is chemically converted graphene prepared from other sources of graphene oxide.

Carbon and Neodymium Isotopic Fingerprints of Atlantic Deep Ocean Circulation During the Warm Pliocene

NASA Astrophysics Data System (ADS)

Riesselman, C. R.; Scher, H.; Robinson, M. M.; Dowsett, H. J.; Bell, D. B.

2012-12-01

Earth's future climate may resemble the mid-Piacenzian Age of the Pliocene, a time when global temperatures were sustained within the range predicted for the coming century. Surface and deep water temperature reconstructions and coupled ocean-atmosphere general circulation model simulations by the USGS PRISM (Pliocene Research Interpretation and Synoptic Mapping) Group identify a dramatic North Atlantic warm surface temperature anomaly in the mid-Piacenzian (3.264 - 3.025 Ma), accompanied by increased evaporation. The anomaly is detected in deep waters at 46°S, suggesting enhanced meridional overturning circulation and more southerly penetration of North Atlantic Deep Water (NADW) during the PRISM interval. However deep water temperature proxies are not diagnostic of water mass and some coupled model simulations predict transient decreases in NADW production in the 21st century, presenting a contrasting picture of future climate. We present a new multi-proxy investigation of Atlantic deep ocean circulation during the warm mid-Piacenzian, using δ13C of benthic foraminifera as a proxy for water mass age and the neodymium isotopic composition of fossil fish teeth (ɛNd) as a proxy for water mass source and mixing. This reconstruction utilizes both new and previously published data from DSDP and ODP cores along equatorial (Ceara Rise), southern mid-latitude (Walvis Ridge), and south Atlantic (Meteor Rise/Agulhas Ridge) depth transects. Additional end-member sites in the regions of modern north Atlantic and Southern Ocean deep water formation provide a Pliocene baseline for comparison. δ13C throughout the Atlantic basin is remarkably homogenous during the PRISM interval. δ13C values of Cibicidoides spp. and C. wuellerstorfi largely range between 0‰ and 1‰ at North Atlantic, shallow equatorial, southern mid-latitude, and south Atlantic sites with water depths from 2000-4700 m; both depth and latitudinal gradients are generally small (~0.3‰). However, equatorial

Lipid oxidation induced oxidative degradation of cereal beta-glucan.

PubMed

Wang, Yu-Jie; Mäkelä, Noora; Maina, Ndegwa Henry; Lampi, Anna-Maija; Sontag-Strohm, Tuula

2016-04-15

In food systems, lipid oxidation can cause oxidation of other molecules. This research for the first time investigated oxidative degradation of β-glucan induced by lipid oxidation using an oil-in-water emulsion system which simulated a multi-phased aqueous food system containing oil and β-glucan. Lipid oxidation was monitored using peroxide value and hexanal production while β-glucan degradation was evaluated by viscosity and molecular weight measurements. The study showed that while lipid oxidation proceeded, β-glucan degradation occurred. Emulsions containing β-glucan, oil and ferrous ion showed significant viscosity and molecular weight decrease after 1 week of oxidation at room temperature. Elevated temperature (40°C) enhanced the oxidation reactions causing higher viscosity drop. In addition, the presence of β-glucan appeared to retard the hexanal production in lipid oxidation. The study revealed that lipid oxidation may induce the degradation of β-glucan in aqueous food systems where β-glucan and lipids co-exist. Copyright © 2015 Elsevier Ltd. All rights reserved.

Oxidizing action of purine N-oxide esters.

PubMed

Stöhrer, G; Salemnick, G

1975-01-01

A technique involving O-acetylation of purine N-oxide derivatives in buffered aqueous solutions has permitted studies of the reactivity of many compounds for which the O-acetyl derivatives are not otherwise available. The oxidizing properties of a variety of N-acetoxypurines have been measured through their ability to oxidize iodide ion ot iodine, a reaction which is representative of a more general oxidizing ability. Those esters that oxidize iodide ion also catalyze the autoxidation of sulfite, a property characteristic of radicals. The same esters also oxidize cysteine to cysteic acid and tryptophan, tyrosine, and uric acid to yet uncharacterized products. Their oxidizing reactivity was compared with the ability of the same esters to react as electrophiles in another assay that measured the rate of formation of pyridine substitution products. The sulfate ester of 3-hydroxyxanthine has been synthesized. Its reactivity is qualitatively the same as that of 3-acetoxyxanthine but proceeds at a higher rate. Syntheses of S-(8-xanthyl)-N-acetylcysteine, 8-(2-hydroxyethylthio)xanthine, and 1-methyl-8-mehtylmercaptoguanine are also described.

Harmonic technology versus neodymium-doped yttrium aluminium garnet laser and electrocautery for lung metastasectomy: an experimental study.

PubMed

Fiorelli, Alfonso; Accardo, Marina; Carelli, Emanuele; Del Prete, Assunta; Messina, Gaetana; Reginelli, Alfonso; Berritto, Daniela; Papale, Ferdinando; Armenia, Emilia; Chiodini, Paolo; Grassi, Roberto; Santini, Mario

2016-07-01

We compared the efficacy of non-anatomical lung resections with that of three other techniques: monopolar electrocautery; neodymium-doped yttrium aluminium garnet laser and harmonic technology. We hypothesized that the thermal damage with harmonic technology could be reduced because of the lower temperatures generated by harmonic technology compared with that of other devices. Initial studies were performed in 13 isolated pig lungs for each group. A 1.5-cm capsule was inserted within the lung to mimic a tumour and a total of 25 non-anatomical resections were performed with each device. The damage of the resected lung surface and of the tumour border were evaluated according to the colour (ranging from 0-pink colour to 4-black colour), histological (ranging from Score 0-no changes to Score 3-presence of necrotic tissue) and radiological (ranging from Score 0-isointense T2 signal at magnetic resonance imaging to Score 3-hyperintense T2 signal) criteria. A total of seven non-anatomical resections with harmonic technology were also performed in two live pigs to assess if ex vivo results could be reproducible in live pigs with particular attention to haemostatic and air-tightness properties. In the ex vivo lung, there was a statistical significant difference between depth of thermal damage (P < 0.0001) in electrocautery (1.3 [1.2-1.4]), laser (0.9 [0.6-0.9]) and harmonic (0.4 [0.3-0.5]) groups. Electrocautery had a higher depth of thermal damage compared with that of the laser (P = 0.01) and harmonic groups (P = 0.0005). The harmonic group had a less depth of thermal damage than that of the laser group (P = 0.01). Also, histological damages of tumour borders (P < 0.001) and resected lung surface (P < 0.001), radiological damage of tumour borders (P < 0.001) and resected lung surface (P < 0.001) and colour changes (P < 0.001) were statistically different between three study groups. Resections of in vivo pig lungs showed no bleeding; 2 of 7 cases of low air leaks were

Complexation of Nd(III) with tetraborate ion and its effect on actinide (III) solubility in WIPP brine

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

Borkowski, Marian; Richmann, Michael K; Reed, Donald T

2010-01-01

The potential importance of tetraborate complexation on lanthanide(III) and actinide(III) solubility is recognized in the literature but a systematic study of f-element complexation has not been performed. In neodymium solubility studies in WIPP brines, the carbonate complexation effect is not observed since tetraborate ions form a moderately strong complex with neodymium(III). The existence of these tetraborate complexes was established for low and high ionic strength solutions. Changes in neodymium(III) concentrations in undersaturation experiments were used to determine the neodymium with tetraborate stability constants as a function of NaCl ionic strength. As very low Nd(III) concentrations have to be measured, itmore » was necessary to use an extraction pre-concentration step combined with ICP-MS analysis to extend the detection limit by a factor of 50. The determined Nd(III) with borate stability constants at infinite dilution and 25 C are equal to log {beta}{sub 1} = 4.55 {+-} 0.06 using the SIT approach, equal to log {beta}{sub 1} = 4.99 {+-} 0.30 using the Pitzer approach, with an apparent log {beta}{sub 1} = 4.06 {+-} 0.15 (in molal units) at I = 5.6 m NaCl. Pitzer ion-interaction parameters for neodymium with tetraborate and SIT interaction coefficients were also determined and reported.« less

Material flow analysis of NdFeB magnets for Denmark: a comprehensive waste flow sampling and analysis approach.

PubMed

Habib, Komal; Schibye, Peter Klausen; Vestbø, Andreas Peter; Dall, Ole; Wenzel, Henrik

2014-10-21

Neodymium-iron-boron (NdFeB) magnets have become highly desirable for modern hi-tech applications. These magnets, in general, contain two key rare earth elements (REEs), i.e., neodymium (Nd) and dysprosium (Dy), which are responsible for the very high strength of these magnets, allowing for considerable size and weight reduction in modern applications. This study aims to explore the current and future potential of a secondary supply of neodymium and dysprosium from recycling of NdFeB magnets. For this purpose, material flow analysis (MFA) has been carried out to perform the detailed mapping of stocks and flows of NdFeB magnets in Denmark. A novel element of this study is the value added to the traditionally practiced MFAs at national and/or global levels by complementing them with a comprehensive sampling and elemental analysis of NdFeB magnets, taken out from a sample of 157 different products representing 18 various product types. The results show that the current amount of neodymium and dysprosium in NdFeB magnets present in the Danish waste stream is only 3 and 0.2 Mg, respectively. However, this number is estimated to increase to 175 Mg of neodymium and 11.4 Mg of dysprosium by 2035. Nevertheless, efficient recovery of these elements from a very diverse electronic waste stream remains a logistic and economic challenge.

Neodymium and strontium isotopic dating of diagenesis and low-grade metamorphism of argillaceous sediments

NASA Astrophysics Data System (ADS)

Schaltegger, Urs; Stille, Peter; Rais, Naoual; Piqué, Alain; Clauer, Norbert

1994-03-01

The behaviour of the Rb-Sr and Sm-Nd isotopic systems with increasing degree of Hercynian metamorphic overprint was studied along a transect in Cambrian shales of northwestern Morocco. Clay fractions of < 0.2 to 2-6 μm size from five samples were investigated, representing a range from nonmetamorphic to epizonal metamorphic conditions. The samples were washed in cold l N HC1 prior to digestion to separate soluble/exchangeable Rb, Sr, Sm, and Nd from amounts of these elements fixed in the crystallographic sites of the minerals and to analyze both components separately. The results reveal that the Rb-Sr isotopic system is dominated by Sr hosted by clay mineral phases (both detrital and authigenic illite and chlorite) and carbonate-hosted soluble Sr. Isotopic homogenization of Sr occurred during Hercynian metamorphism, yielding ages between 309 and 349 Ma. The Sm-Nd isotopic system, on the other hand, is dominated by cogenetic apatite and Fe oxide/ hydroxide, both having high contents of leachable REEs. The leachates yield a Sm-Nd isochron age of 523 ± 72 Ma, indicating diagenetic equilibrium between apatite and Fe-oxide/hydroxide. Fine-grained clay fractions of < 0.2 μm size plot onto this reference line, suggesting isotopic equilibrium with the leachates. Size fractions > 0.2 μm show inheritance of a detrital Nd component. The study demonstrates that the diagenesis of the investigated argillaceous sediments can be dated by the Sm-Nd chronometer in authigenic cement phases. The isotopic system of these minerals (apatite, Fe hydroxide/oxide) was homogenized during authigenic mineral growth in a sediment that was flushed by diagenetic fluids and had abundant primary or secondary interconnected pore space. The Hercynian metamorphic overprint caused partial isotopic rehomogenization of the adsorbed and clay-hosted portion of the Sr as well as of the carbonate-hosted Sr. The Sm-Nd system in the cement phases survived this metamorphism. This results in decoupling of

Oxidative Stress, Nitric Oxide, and Diabetes

PubMed Central

Pitocco, Dario; Zaccardi, Francesco; Di Stasio, Enrico; Romitelli, Federica; Santini, Stefano A.; Zuppi, Cecilia; Ghirlanda, Giovanni

2010-01-01

In the recent decades, oxidative stress has become focus of interest in most biomedical disciplines and many types of clinical research. Increasing evidence from research on several diseases show that oxidative stress is associated with the pathogenesis of diabetes, obesity, cancer, ageing, inflammation, neurodegenerative disorders, hypertension, apoptosis, cardiovascular diseases, and heart failure. Based on this research, the emerging concept is that oxidative stress is the “final common pathway”, through which risk factors of several diseases exert their deleterious effects. Oxidative stress causes a complex dysregulation of cell metabolism and cell-cell homeostasis. In this review, we discuss the role of oxidative stress in the pathogenesis of insulin resistance and beta-cell dysfunction. These are the two most relevant mechanisms in the pathophysiology of type 2 diabetes, and in the pathogenesis of diabetic vascular complications, the leading cause of death in diabetic patients. PMID:20703435

Single-Phase Rare-Earth Oxide/Aluminum Oxide Glasses

NASA Technical Reports Server (NTRS)

Weber, J. K. Richard; Abadie, John G.; Hixson, April D.; Nordine, Paul C.

2006-01-01

Glasses that comprise rare-earth oxides and aluminum oxide plus, optionally, lesser amounts of other oxides, have been invented. The other oxide(s) can include SiO2, B2O3, GeO2, and/or any of a variety of glass-forming oxides that have been used heretofore in making a variety of common and specialty glasses. The glasses of the invention can be manufactured in bulk single-phase forms to ensure near uniformity in optical and mechanical characteristics, as needed for such devices as optical amplifiers, lasers, and optical waveguides (including optical fibers). These glasses can also be formulated to have high indices of refraction, as needed in some of such devices.

Opportunities for functional oxides in yttrium oxide-titanium oxide-zirconium oxide system: Applications for novel thermal barrier coatings

NASA Astrophysics Data System (ADS)

Francillon, Wesley

This dissertation is an investigation of materials and processed under consideration for next generation thermal structural oxides with potential applications as thermal barrier coatings; wherein, high temperature stability and mechanical properties affect durability. Two notable next generation materials systems under investigation are pyrochlore and co-doped zirconia oxides. The motivation for this work is based on current limitations of the currently used thermal barrier material of yttria stabilized zirconia (YSZ) deposited by the plasma spray processes. The rapid quenching associated with the plasma spray process, results in a metastable structure that is a non-transformable tetragonal structure in the yttria partially stabilized zirconia system rather than the equilibrium anticipated two phase mixture of cubic and monoclinic phases. It has been shown that this metastable structure offers enhanced toughness and thus durability during thermomechanical cycling from the operating temperatures in excess of 1000C to ambient. However, the metastable oxides are susceptible to partitioning at temperatures greater than 1200C, thus resulting in a transformation of the tetragonal phase oxides. Transformations of the tetragonal prime phase into the parent cubic and tetragonal prime phase result in coating degradation. Several of the emerging oxides are based on rare earth additions to zirconia. However, there is limited information of the high temperature stability of these oxide coatings and more notably these compositions exhibit limited toughness for durable performance. A potential ternary composition based on the YSZ system that offers the ability to tailor the phase structure is based YO1.5-TiO2 -ZrO2. The ternary of YO1.5-TiO2-ZrO 2 has the current TBC composition of seven molar percent yttria stabilized zirconia, pyrochlore phase oxide and zirconia doped with yttria and titania additions (Ti-YSZ). The Ti-YSZ phase field is of interest because at equilibrium it is

Metabolism of Nitrogen Oxides in Ammonia-Oxidizing Bacteria

NASA Astrophysics Data System (ADS)

Kozlowski, J.; Stein, L. Y.

2014-12-01

Ammonia-oxidizing bacteria (AOB) are key microorganisms in the transformation of nitrogen intermediates in most all environments. Until recently there was very little work done to elucidate the physiology of ammonia-oxidizing bacteria cultivated from variable trophic state environments. With a greater variety of ammonia-oxidizers now in pure culture the importance of comparative physiological and genomic analysis is crucial. Nearly all known physiology of ammonia-oxidizing bacteria lies within the Nitrosomonas genus with Nitrosomonas europaea strain ATCC 19718 as the model. To more broadly characterize and understand the nature of obligate ammonia chemolithotrophy and the contribution of AOB to production of nitrogen oxides, Nitrosomonas spp. and Nitrosospira spp. isolated from variable trophic states and with sequenced genomes, were utilized. Instantaneous ammonia- and hydroxylamine-oxidation kinetics as a function of oxygen and substrate concentration were measured using an oxygen micro-sensor. The pathway intermediates nitric oxide and nitrous oxide were measured in real time using substrate-specific micro-sensors to elucidate whether production of these molecules is stoichiometric with rates of substrate oxidation. Genomic inventory was compared among the strains to identify specific pathways and modules to explain physiological differences in kinetic rates and production of N-oxide intermediates as a condition of their adaptation to different ammonium concentrations. This work provides knowledge of how nitrogen metabolism is differentially controlled in AOB that are adapted to different concentrations of ammonium. Overall, this work will provide further insight into the control of ammonia oxidizing chemolithotrophy across representatives of the Nitrosomonas and Nitrosospira genus, which can then be applied to examine additional genome-sequenced AOB isolates.

Comparative Study of Diode Laser Versus Neodymium-Yttrium Aluminum: Garnet Laser Versus Intense Pulsed Light for the Treatment of Hirsutism

PubMed Central

Puri, Neerja

2015-01-01

Introduction: Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. Aims: To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminum — garnet (Nd: YAG) laser and intense pulsed light (IPL) on 30 female patients of hirsutism. Materials and Methods: Thirty female patients with hirsutism were selected for a randomised controlled study. The patients were divided into three groups of 10 patients each. In group I patients diode laser was used, in group II patients long pulsed Nd: YAG laser was used and in group III, IPL was used. The patients were evaluated and result graded according to a 4-point scale as excellent, >75% reduction; good, 50-75% reduction; fair; 25-50% reduction; and poor, <25% reduction in hair density. Results: It was seen that the percentage of hair reduction after two sessions of treatment was maximum (40%) in the diode laser group, followed by 35% hair reduction in the Nd: Yag laser group and 10% hair reduction in the IPL group. The percentage of hair reduction after four sessions of treatment was maximum (64%) in the diode laser group, followed by 62% hair reduction in the Nd: Yag laser group and 48% hair reduction in the IPL group. The percentage of hair reduction after eight sessions of treatment was maximum (92%) in the diode laser group, followed by 90% hair reduction in the Nd: YAG group and 70% hair reduction in the IPL group. Conclusions: To conclude for the Indian skin with dark hairs, the diode laser still stands the test of time. But, since the diode laser has a narrow margin of safety, proper pre and post-procedure cooling is recommended. Although, the side effects of Nd: YAG laser are less as compared to the diode laser, it is less efficacious as compared to the diode laser. PMID:26157309

Chromium(iii) oxidation by biogenic manganese oxides with varying structural ripening.

PubMed

Tang, Yuanzhi; Webb, Samuel M; Estes, Emily R; Hansel, Colleen M

2014-09-20

Manganese (Mn) oxides, which are generally considered biogenic in origin within natural systems, are the only oxidants of Cr(iii) under typical environmental conditions. Yet the influence of Mn biooxide mineral structural evolution on Cr(iii) oxidation under varying geochemical conditions is unknown. In this study we examined the role of light, organic carbon, pH, and the structure of biogenic Mn oxides on Cr(iii) oxidation. Aging of Mn oxides produced by a marine bacterium within the widespread Roseobacter clade resulted in structural ripening from a colloidal hexagonal to a particulate triclinic birnessite phase. The structurally diverse Mn oxides were then reacted with aqueous Cr(iii) within artificial seawater in the presence or absence of carbon and light. Here we found that Cr(iii) oxidation capacity was highest at near neutral pH and in the combined presence of carbon and light. Mn oxide ripening from a hexagonal to a triclinic birnessite phase led to decreased Cr(iii) oxidation in the presence of carbon and light, whereas no change in reactivity was observed in the absence of carbon and/or in the dark. As only minimal Cr(iii) oxidation was observed in the absence of Mn oxides, these results strongly point to coupled Mn oxide- and photo-induced generation of organic and/or oxygen radicals involved in Cr(iii) oxidation. Based on Mn oxide concentration and structural trends, we postulate that Mn(ii) produced from the oxidation of Cr(iii) by the primary Mn oxide is recycled in the presence of organics and light conditions, (re)generating secondary hexagonal birnessite and thereby allowing for continuous oxidation of Cr(iii). In the absence of this Mn oxide regeneration, Cr(iii) induced structural ripening of the hexagonal birnessite precludes further Cr(iii) oxidation. These results highlight the complexity of reactions involved in Mn oxide mediated Cr(iii) oxidation and suggest that photochemical carbon reactions are requisite for sustained Cr(iii) oxidation

Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: membrane and oxidative stress.

PubMed

Liu, Shaobin; Zeng, Tingying Helen; Hofmann, Mario; Burcombe, Ehdi; Wei, Jun; Jiang, Rongrong; Kong, Jing; Chen, Yuan

2011-09-27

Health and environmental impacts of graphene-based materials need to be thoroughly evaluated before their potential applications. Graphene has strong cytotoxicity toward bacteria. To better understand its antimicrobial mechanism, we compared the antibacterial activity of four types of graphene-based materials (graphite (Gt), graphite oxide (GtO), graphene oxide (GO), and reduced graphene oxide (rGO)) toward a bacterial model-Escherichia coli. Under similar concentration and incubation conditions, GO dispersion shows the highest antibacterial activity, sequentially followed by rGO, Gt, and GtO. Scanning electron microscope (SEM) and dynamic light scattering analyses show that GO aggregates have the smallest average size among the four types of materials. SEM images display that the direct contacts with graphene nanosheets disrupt cell membrane. No superoxide anion (O(2)(•-)) induced reactive oxygen species (ROS) production is detected. However, the four types of materials can oxidize glutathione, which serves as redox state mediator in bacteria. Conductive rGO and Gt have higher oxidation capacities than insulating GO and GtO. Results suggest that antimicrobial actions are contributed by both membrane and oxidation stress. We propose that a three-step antimicrobial mechanism, previously used for carbon nanotubes, is applicable to graphene-based materials. It includes initial cell deposition on graphene-based materials, membrane stress caused by direct contact with sharp nanosheets, and the ensuing superoxide anion-independent oxidation. We envision that physicochemical properties of graphene-based materials, such as density of functional groups, size, and conductivity, can be precisely tailored to either reducing their health and environmental risks or increasing their application potentials. © 2011 American Chemical Society

Oxidation behaviour and electrical properties of cobalt/cerium oxide composite coatings for solid oxide fuel cell interconnects

NASA Astrophysics Data System (ADS)

Harthøj, Anders; Holt, Tobias; Møller, Per

2015-05-01

This work evaluates the performance of cobalt/cerium oxide (Co/CeO2) composite coatings and pure Co coatings to be used for solid oxide fuel cell (SOFC) interconnects. The coatings are electroplated on the ferritic stainless steels Crofer 22 APU and Crofer 22H. Coated and uncoated samples are exposed in air at 800 °C for 3000 h and oxidation rates are measured and oxide scale microstructures are investigated. Area-specific resistances (ASR) in air at 850 °C of coated and uncoated samples are also measured. A dual layered oxide scale formed on all coated samples. The outer layer consisted of Co, Mn, Fe and Cr oxide and the inner layer consisted of Cr oxide. The CeO2 was present as discrete particles in the outer oxide layer after exposure. The Cr oxide layer thicknesses and oxidations rates were significantly reduced for Co/CeO2 coated samples compared to for Co coated and uncoated samples. The ASR of all Crofer 22H samples increased significantly faster than of Crofer 22 APU samples which was likely due to the presence of SiO2 in the oxide/metal interface of Crofer 22H.

Microsomal oxidation of tribromoethylene and reactions of tribromoethylene oxide.

PubMed

Yoshioka, Tadao; Krauser, Joel A; Guengerich, F Peter

2002-11-01

Halogenated olefins are of interest because of their widespread use in industry and their potential toxicity to humans. Epoxides are among the enzymatic oxidation products and have been studied in regard to their toxicity. Most of the attention has been given to chlorinated epoxides, and we have previously studied the reactions of the mono-, di-, tri-, and tetrachloroethylene oxides. To further test some hypotheses concerning the reactivity of these compounds, we prepared tribromoethylene (TBE) oxide and compared it to trichloroethylene (TCE) oxide and other chlorinated epoxides. TBE oxide reacted with H(2)O about 3 times faster than did TCE oxide. Several hydrolysis products of TBE oxide were the same as formed from TCE oxide, i.e., glyoxylic acid, CO, and HCO(2)H. Br(2)CHCO(2)H was formed from TBE oxide; the yield was higher than for Cl(2)CHCO(2)H formed in the hydrolysis of TCE oxide. The yield of tribromoacetaldehyde was < 0.4% in aqueous buffer (pH 7.4). In rat liver microsomal incubations containing TBE and NADPH, Br(2)CHCO(2)H was a major product, and tribromoacetaldehyde was a minor product. These results are consistent with schemes previously developed for halogenated epoxides, with migration of bromine being more favorable than for chlorine. Reaction of TBE oxide with lysine yielded relatively more N-dihaloacetyllysine and less N-formyllysine than in the case of TCE oxide. This same pattern was observed in the products of the reaction of TBE oxide with the lysine residues in bovine serum albumin. We conclude that the proposed scheme of hydrolysis of halogenated epoxides follows the expected halide order and that this can be used to rationalize patterns of hydrolysis and reactivity of other halogenated epoxides.

Effects of Oxidation on Oxidation-Resistant Graphite

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

Windes, William; Smith, Rebecca; Carroll, Mark

2015-05-01

The Advanced Reactor Technology (ART) Graphite Research and Development Program is investigating doped nuclear graphite grades that exhibit oxidation resistance through the formation of protective oxides on the surface of the graphite material. In the unlikely event of an oxygen ingress accident, graphite components within the VHTR core region are anticipated to oxidize so long as the oxygen continues to enter the hot core region and the core temperatures remain above 400°C. For the most serious air-ingress accident which persists over several hours or days the continued oxidation can result in significant structural damage to the core. Reducing the oxidationmore » rate of the graphite core material during any air-ingress accident would mitigate the structural effects and keep the core intact. Previous air oxidation testing of nuclear-grade graphite doped with varying levels of boron-carbide (B4C) at a nominal 739°C was conducted for a limited number of doped specimens demonstrating a dramatic reduction in oxidation rate for the boronated graphite grade. This report summarizes the conclusions from this small scoping study by determining the effects of oxidation on the mechanical strength resulting from oxidation of boronated and unboronated graphite to a 10% mass loss level. While the B4C additive did reduce mechanical strength loss during oxidation, adding B4C dopants to a level of 3.5% or more reduced the as-fabricated compressive strength nearly 50%. This effectively minimized any benefits realized from the protective film formed on the boronated grades. Future work to infuse different graphite grades with silicon- and boron-doped material as a post-machining conditioning step for nuclear components is discussed as a potential solution for these challenges in this report.« less

Modulatory effects by neodymium-doped yttrium aluminum garnet laser on fibroblast attachment to single rooted tooth surfaces following ultrasonic scaling and root planning: An in vitro study

PubMed Central

Negi, Shanta; Krishnamurthy, Malathi; Ganji, Kiran Kumar; Pendor, Sunil

2015-01-01

Context: One of the most important goals of periodontal therapy is connective tissue reattachment to previously diseased root surfaces. In the recent years, laser therapy has been considered as an important tool in improving the treatment of periodontal disease. Aims: To evaluate the neodymium-doped yttrium aluminum garnet (Nd: YAG) lasers effects on root surfaces affected by periodontal disease and compare this treatment with scaling and root planning (SRP) in terms of fibroblast attachment. Materials and Methods: A sample of 30 single-rooted human teeth extracted because of advanced periodontal disease was used in this study. Sixty specimens obtained by longitudinal sectioning were randomly divided in three groups. Group A control (untreated); Group B SRP; Group C laser (Nd: YAG) and ultrasonic scaling. All specimens were incubated with fibroblast suspension and then fixed and observed under scanning electron microscope. Results: With a median of 8, the control group (Group A) exhibited the least number of total fibroblasts among all the three groups. The laser and scaling - treated group (Group C) showed the highest number of fibroblasts (median = 49, mean ± standard deviation [SD] = 48.28 ± 17.18), followed by SRP only (Group B, median = 22, mean ± SD = 22.24 ± 8.67). Conclusions: Nd: YAG laser irradiation at specific energy densities can be used as a useful tool to condition the root surfaces, enhancing fibroblast attachment. Hence aiding in re-establishment of the connective tissue attachment to the root surfaces of previously diseased teeth. PMID:25810589

CO-oxidation catalysts: Low-temperature CO oxidation over Noble-Metal Reducible Oxide (NMRO) catalysts

NASA Technical Reports Server (NTRS)

Herz, Richard K.

1990-01-01

Oxidation of CO to CO2 is an important reaction technologically and environmentally and a complex and interesting reaction scientifically. In most cases, the reaction is carried out in order to remove CO as an environmental hazard. A major application of heterogeneous catalysts is catalytic oxidation of CO in the exhaust of combustion devices. The reaction over catalysts in exhaust gas is fast and often mass-transfer-limited since exhaust gases are hot and O2/CO ratios are high. The main challenges to catalyst designers are to control thermal sintering and chemical poisoning of the active materials. The effect of the noble metal on the oxide is discussed, followed by the effect of the oxide on the noble metal, the interaction of the noble metal and oxide to form unique catalytic sites, and the possible ways in which the CO oxidation reaction is catalyzed by the NMRO materials.

Superoxide Production by a Manganese-Oxidizing Bacterium Facilitates Iodide Oxidation

PubMed Central

Li, Hsiu-Ping; Daniel, Benjamin; Creeley, Danielle; Grandbois, Russell; Zhang, Saijin; Xu, Chen; Ho, Yi-Fang; Schwehr, Kathy A.; Kaplan, Daniel I.; Santschi, Peter H.; Hansel, Colleen M.

2014-01-01

The release of radioactive iodine (i.e., iodine-129 and iodine-131) from nuclear reprocessing facilities is a potential threat to human health. The fate and transport of iodine are determined primarily by its redox status, but processes that affect iodine oxidation states in the environment are poorly characterized. Given the difficulty in removing electrons from iodide (I−), naturally occurring iodide oxidation processes require strong oxidants, such as Mn oxides or microbial enzymes. In this study, we examine iodide oxidation by a marine bacterium, Roseobacter sp. AzwK-3b, which promotes Mn(II) oxidation by catalyzing the production of extracellular superoxide (O2−). In the absence of Mn2+, Roseobacter sp. AzwK-3b cultures oxidized ∼90% of the provided iodide (10 μM) within 6 days, whereas in the presence of Mn(II), iodide oxidation occurred only after Mn(IV) formation ceased. Iodide oxidation was not observed during incubations in spent medium or with whole cells under anaerobic conditions or following heat treatment (boiling). Furthermore, iodide oxidation was significantly inhibited in the presence of superoxide dismutase and diphenylene iodonium (a general inhibitor of NADH oxidoreductases). In contrast, the addition of exogenous NADH enhanced iodide oxidation. Taken together, the results indicate that iodide oxidation was mediated primarily by extracellular superoxide generated by Roseobacter sp. AzwK-3b and not by the Mn oxides formed by this organism. Considering that extracellular superoxide formation is a widespread phenomenon among marine and terrestrial bacteria, this could represent an important pathway for iodide oxidation in some environments. PMID:24561582

Superoxide production by a manganese-oxidizing bacterium facilitates iodide oxidation.

PubMed

Li, Hsiu-Ping; Daniel, Benjamin; Creeley, Danielle; Grandbois, Russell; Zhang, Saijin; Xu, Chen; Ho, Yi-Fang; Schwehr, Kathy A; Kaplan, Daniel I; Santschi, Peter H; Hansel, Colleen M; Yeager, Chris M

2014-05-01

The release of radioactive iodine (i.e., iodine-129 and iodine-131) from nuclear reprocessing facilities is a potential threat to human health. The fate and transport of iodine are determined primarily by its redox status, but processes that affect iodine oxidation states in the environment are poorly characterized. Given the difficulty in removing electrons from iodide (I(-)), naturally occurring iodide oxidation processes require strong oxidants, such as Mn oxides or microbial enzymes. In this study, we examine iodide oxidation by a marine bacterium, Roseobacter sp. AzwK-3b, which promotes Mn(II) oxidation by catalyzing the production of extracellular superoxide (O2(-)). In the absence of Mn(2+), Roseobacter sp. AzwK-3b cultures oxidized ∼90% of the provided iodide (10 μM) within 6 days, whereas in the presence of Mn(II), iodide oxidation occurred only after Mn(IV) formation ceased. Iodide oxidation was not observed during incubations in spent medium or with whole cells under anaerobic conditions or following heat treatment (boiling). Furthermore, iodide oxidation was significantly inhibited in the presence of superoxide dismutase and diphenylene iodonium (a general inhibitor of NADH oxidoreductases). In contrast, the addition of exogenous NADH enhanced iodide oxidation. Taken together, the results indicate that iodide oxidation was mediated primarily by extracellular superoxide generated by Roseobacter sp. AzwK-3b and not by the Mn oxides formed by this organism. Considering that extracellular superoxide formation is a widespread phenomenon among marine and terrestrial bacteria, this could represent an important pathway for iodide oxidation in some environments.

The 2016 oxide electronic materials and oxide interfaces roadmap

NASA Astrophysics Data System (ADS)

Lorenz, M.; Ramachandra Rao, M. S.; Venkatesan, T.; Fortunato, E.; Barquinha, P.; Branquinho, R.; Salgueiro, D.; Martins, R.; Carlos, E.; Liu, A.; Shan, F. K.; Grundmann, M.; Boschker, H.; Mukherjee, J.; Priyadarshini, M.; DasGupta, N.; Rogers, D. J.; Teherani, F. H.; Sandana, E. V.; Bove, P.; Rietwyk, K.; Zaban, A.; Veziridis, A.; Weidenkaff, A.; Muralidhar, M.; Murakami, M.; Abel, S.; Fompeyrine, J.; Zuniga-Perez, J.; Ramesh, R.; Spaldin, N. A.; Ostanin, S.; Borisov, V.; Mertig, I.; Lazenka, V.; Srinivasan, G.; Prellier, W.; Uchida, M.; Kawasaki, M.; Pentcheva, R.; Gegenwart, P.; Miletto Granozio, F.; Fontcuberta, J.; Pryds, N.

2016-11-01

Oxide electronic materials provide a plethora of possible applications and offer ample opportunity for scientists to probe into some of the exciting and intriguing phenomena exhibited by oxide systems and oxide interfaces. In addition to the already diverse spectrum of properties, the nanoscale form of oxides provides a new dimension of hitherto unknown phenomena due to the increased surface-to-volume ratio. Oxide electronic materials are becoming increasingly important in a wide range of applications including transparent electronics, optoelectronics, magnetoelectronics, photonics, spintronics, thermoelectrics, piezoelectrics, power harvesting, hydrogen storage and environmental waste management. Synthesis and fabrication of these materials, as well as processing into particular device structures to suit a specific application is still a challenge. Further, characterization of these materials to understand the tunability of their properties and the novel properties that evolve due to their nanostructured nature is another facet of the challenge. The research related to the oxide electronic field is at an impressionable stage, and this has motivated us to contribute with a roadmap on ‘oxide electronic materials and oxide interfaces’. This roadmap envisages the potential applications of oxide materials in cutting edge technologies and focuses on the necessary advances required to implement these materials, including both conventional and novel techniques for the synthesis, characterization, processing and fabrication of nanostructured oxides and oxide-based devices. The contents of this roadmap will highlight the functional and correlated properties of oxides in bulk, nano, thin film, multilayer and heterostructure forms, as well as the theoretical considerations behind both present and future applications in many technologically important areas as pointed out by Venkatesan. The contributions in this roadmap span several thematic groups which are represented by

Barium oxide, calcium oxide, magnesia, and alkali oxide free glass

DOEpatents

Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

2013-09-24

A glass composition consisting essentially of about 10-45 mole percent of SrO; about 35-75 mole percent SiO.sub.2; one or more compounds from the group of compounds consisting of La.sub.2O.sub.3, Al.sub.2O.sub.3, B.sub.2O.sub.3, and Ni; the La.sub.2O.sub.3 less than about 20 mole percent; the Al.sub.2O.sub.3 less than about 25 mole percent; the B.sub.2O.sub.3 less than about 15 mole percent; and the Ni less than about 5 mole percent. Preferably, the glass is substantially free of barium oxide, calcium oxide, magnesia, and alkali oxide. Preferably, the glass is used as a seal in a solid oxide fuel/electrolyzer cell (SOFC) stack. The SOFC stack comprises a plurality of SOFCs connected by one or more interconnect and manifold materials and sealed by the glass. Preferably, each SOFC comprises an anode, a cathode, and a solid electrolyte.

Recycling-Oriented Product Characterization for Electric and Electronic Equipment as a Tool to Enable Recycling of Critical Metals

NASA Astrophysics Data System (ADS)

Rotter, Vera Susanne; Chancerel, Perrine; Ueberschaar, Maximilian

To establish a knowledge base for new recycling processes of critical elements, recycling-orientated product characterization for Electric and Electronic Equipment (EEE) can be used as a tool. This paper focuses on necessary data and procedures for a successful characterization and provides information about existing scientific work. The usage of this tool is illustrated for two application: Hard Disk Drives (HDD) and Liquid Crystal Display (LCD) panels. In the first case it could be shown that Neodymium and other Rare Earth Elements are concentrated in magnets (25% by weight) and contribute largely to the end demand of Neodymium. Nevertheless, recycling is limited by the difficult liberation and competing other target metals contained in HDD. In the second case it could be shown that also for this application the usage of Indium is concentrated in LCDs, but unlike in magnets the concentration is lower (200 ppm). The design of LCDs with two glued glass layers and the Indium-Tin-Oxide layer in between make the Indium inaccessible for hydro-metallurgical recovery, the glass content puts energetic limitations on pyro-metallurgical processes. For the future technical development of recycling infrastructure we need an in depth understanding of product design and recycling relevant parameters for product characterization focusing on new target metals. This product-centered approach allows also re-think traditional "design for recycling" approaches.

Volatilization of oxides during oxidation of some superalloys at 1200 C

NASA Technical Reports Server (NTRS)

Zaplatynsky, I.

1977-01-01

Volatilization of oxides during cyclic oxidation of commercial Nichrome, Inconel 750, Rene 41, Stellite 6B, and GE-1541 was studied at 1200 C in static air. Quantitative analysis of oxide vapor deposits revealed that oxides of tungsten, molybdenum, niobium, manganese, and chromium volatilized preferentially from the oxide scales. Aluminum and silicon were not detected in vapor deposits. For all the alloys except GE-1541 chromium was found to be the main metallic element in the oxide scales.

Volatilization of oxides during oxidation of some superalloys at 1200 C

NASA Technical Reports Server (NTRS)

Zaplatynsky, I.

1977-01-01

Volatilization of oxides during cyclic oxidation of commercial Nichrome, Inconel 750, Rene 41, Stellite 6B, and GE-1541 was studied at 1200 C in static air. Quantitative analysis of oxide vapor deposits revealed that oxides of tungsten, molybdenum, niobium, manganese, and chromium volatilized preferentially from the oxide scales. Aluminum and silicon were not detected in vapor deposits. For all the alloys except GE-1541, chromium was found to be the main metallic element in the oxide scales.

Nanostructured manganese oxide/carbon nanotubes, graphene and graphene oxide as water-oxidizing composites in artificial photosynthesis.

PubMed

Najafpour, Mohammad Mahdi; Rahimi, Fahime; Fathollahzadeh, Maryam; Haghighi, Behzad; Hołyńska, Małgorzata; Tomo, Tatsuya; Allakhverdiev, Suleyman I

2014-07-28

Herein, we report on nano-sized Mn oxide/carbon nanotubes, graphene and graphene oxide as water-oxidizing compounds in artificial photosynthesis. The composites are synthesized by different and simple procedures and characterized by a number of methods. The water-oxidizing activities of these composites are also considered in the presence of cerium(IV) ammonium nitrate. Some composites are efficient Mn-based catalysts with TOF (mmol O2 per mol Mn per second) ~ 2.6.

Quantitative SIMS depth profiling of diffusion barrier gate-oxynitride structures in TFT-LCDs.

PubMed

Dreer, Sabine; Wilhartitz, Peter; Piplits, Kurt; Mayerhofer, Karl; Foisner, Johann; Hutter, Herbert

2004-06-01

Gate oxynitride structures of TFT-LCDs were investigated by SIMS, and successful solutions are demonstrated to overcome difficulties arising due to the charging effects of the multilayer systems, the matrix effect of the method, and the small pattern sizes of the samples. Because of the excellent reproducibility achieved by applying exponential relative sensitivity functions for quantitative analysis, minor differences in the barrier gate-oxynitride composition deposited on molybdenum capped aluminium-neodymium metallisation electrodes were determined between the centre and the edge of the TFT-LCD substrates. No differences were found for molybdenum-tungsten metallisations. Furthermore, at the edge of the glass substrates, aluminium, neodymium, and molybdenum SIMS depth profiles show an exponential trend. With TEM micrographs an inhomogeneous thickness of the molybdenum capping is revealed as the source of this effect, which influences the electrical behaviour of the device. The production process was improved after these results and the aging behaviour of TFT-LCDs was investigated in order to explain the change in control voltage occurring during the lifetime of the displays. SIMS and TEM show an enrichment of neodymium at the interface to the molybdenum layer, confirming good diffusion protection of the molybdenum barrier during accelerated aging. The reason for the shift of the control voltage was finally located by semi-quantitative depth profiling of the sodium diffusion originating from the glass substrate. Molybdenum-tungsten was a much better buffer for the highly-mobile charge carriers than aluminium-neodymium. Best results were achieved with PVD silicon oxynitride as diffusion barrier and gate insulator deposited on aluminium-neodymium metallisation layers.

Oxidized limonene and oxidized linalool - concomitant contact allergy to common fragrance terpenes.

PubMed

Bråred Christensson, Johanna; Karlberg, Ann-Therese; Andersen, Klaus E; Bruze, Magnus; Johansen, Jeanne D; Garcia-Bravo, Begoña; Giménez Arnau, Ana; Goh, Chee-Leok; Nixon, Rosemary; White, Ian R

2016-05-01

Limonene and linalool are common fragrance terpenes. Both oxidized R-limonene and oxidized linalool have recently been patch tested in an international setting, showing contact allergy in 5.2% and 6.9% of dermatitis patients, respectively. To investigate concomitant reactions between oxidized R-limonene and oxidized linalool in consecutive dermatitis patients. Oxidized R-limonene 3.0% (containing limonene hydroperoxides 0.33%) and oxidized linalool 6% (linalool hydroperoxides 1%) in petrolatum were tested in 2900 consecutive dermatitis patients in Australia, Denmark, Singapore, Spain, Sweden, and the United Kingdom. A total of 281 patients reacted to either oxidized R-limonene or oxidized linalool. Of these, 25% had concomitant reactions to both compounds, whereas 29% reacted only to oxidized R-limonene and 46% only to oxidized linalool. Of the 152 patients reacting to oxidized R-limonene, 46% reacted to oxidized linalool, whereas 35% of the 200 patients reacting to oxidized linalool also reacted to oxidized R-limonene. The majority of the patients (75%) reacted to only one of the oxidation mixtures, thus supporting the specificity of the reactions. The concomitant reactions to the two fragrance allergens suggest multiple sensitizations, which most likely reflect the exposure to the different fragrance materials in various types of consumer products. This is in accordance with what is generally seen for patch test reactions to fragrance materials. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Chromatographic extraction with di(2-ethylhexyl)orthophosphoric acid for production and purification of promethium-147

DOEpatents

Boll, Rose A [Knoxville, TN; Mirzadeh, Saed [Knoxville, TN

2008-10-14

A method of producing and purifying promethium-147 including the steps of: irradiating a target material including neodymium-146 with neutrons to produce promethium-147 within the irradiated target material; dissolving the irradiated target material to form an acidic solution; loading the acidic solution onto a chromatographic separation apparatus containing HDEHP; and eluting the apparatus to chromatographically separate the promethium-147 from the neodymium-146.

Oxidation of silicon nitride sintered with rare-earth oxide additions

NASA Technical Reports Server (NTRS)

Mieskowski, D. M.; Sanders, W. A.

1985-01-01

The effects of rare-earth oxide additions on the oxidation of sintered Si3N4 were examined. Insignificant oxidation occurred at 700 and 1000 C, with no evidence of phase instability. At 1370 C, the oxidation rate was lowest for Y2O3 and increased for additions of La2O3, Sm2O3, and CeO2, in that order. Data obtained from X-ray diffraction, electron microprobe analysis, and scanning electron microscopy indicate that oxidation occurs via diffusion of cationic species from Si3N4 grain boundaries.

Charge Trapping in Low Temperature MOS (Metal-Oxide-Silicon) Oxides.

DTIC Science & Technology

1984-08-24

high pressure thermal oxidation (HIPOX). The LPCVD process involved reaction of dichlorosilane with nitrous oxide. The HIPOX process involved dry...oxygen. The LPCVD and HIPOX films were subjected to a variety of annealing treatments. We have systematically investigated the effects of these treatments...systematically altered by annealing treatments. In general, the electron traps in LPCVD oxide films produced by the nitrous oxide- dichlorosilane

Structural, electronic and chemical properties of metal/oxide and oxide/oxide interfaces and thin film structures

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

Lad, Robert J.

1999-12-14

This project focused on three different aspects of oxide thin film systems: (1) Model metal/oxide and oxide/oxide interface studies were carried out by depositing ultra-thin metal (Al, K, Mg) and oxide (MgO, AlO{sub x}) films on TiO{sub 2}, NiO and {alpha}-Al{sub 2}O{sub 3} single crystal oxide substrates. (2) Electron cyclotron resonance (ECR) oxygen plasma deposition was used to fabricate AlO{sub 3} and ZrO{sub 2} films on sapphire substrates, and film growth mechanisms and structural characteristics were investigated. (3) The friction and wear characteristics of ZrO{sub 2} films on sapphire substrates in unlubricated sliding contact were studied and correlated with filmmore » microstructure. In these studies, thin film and interfacial regions were characterized using diffraction (RHEED, LEED, XRD), electron spectroscopies (XPS, UPS, AES), microscopy (AFM) and tribology instruments (pin-on-disk, friction microprobe, and scratch tester). By precise control of thin film microstructure, an increased understanding of the structural and chemical stability of interface regions and tribological performance of ultra-thin oxide films was achieved in these important ceramic systems.« less

Fingerprinting Bacterial and Fungal Manganese Oxidation via Stable Oxygen Isotopes of Manganese Oxides

NASA Astrophysics Data System (ADS)

Sutherland, K. M.; Wankel, S. D.; Hansel, C. M.

2016-12-01

Manganese (Mn) oxides are a ubiquitous mineralogical component of surface Earth and Mars. Mn(III/IV) oxides are potent environmental sorbents and oxidants that play a crucial role in the fate of organic matter. The processes by which Mn(II) oxidation occurs in natural systems are poorly understood, but a number of studies have implicated microogranisms as the primary agents of Mn(II) oxidation in terrestrial and marine environments. The ability of microorganisms to oxidize Mn(II) to Mn(III/IV) oxides transcends the boundaries of biological domain, with an abundance of well-characterized prokaryotes as well as eukaryotic fungi with the ability to oxidize Mn(II) to Mn(III/IV) oxides. Biological Mn(II) oxidation proceeds directly through enzymatic activity or indirectly through the production of reactive oxygen species. Building upon earlier research suggesting that stable oxygen isotope fractionation could be used to fingerprint unique Mn(II)-oxidizing organisms or distinct oxidation pathways, here we use culture-based studies of Mn(II)-oxidizing bacteria and fungi to determine the kinetic oxygen isotope effects associated with Mn(II) oxidation. Since the oxygen molecules in Mn(III/IV) oxides are comprised of oxygen from both precursor water and molecular oxygen, we used a two-fold approach to constrain isotope fractionation with respect to each oxygen source. We used open system oxidation experiments using oxygen-18 labeled water in parallel with closed system Rayleigh distillation oxidation experiments to fully constrain isotope fractionation associated with oxygen atom incorporation during Mn(II) oxidation. Our results suggest commonalities among fractionation factors from groups of Mn(II)-oxidizing organisms that have similar oxidation mechanisms. These results suggest that stable oxygen isotopes of Mn(III/IV) oxides have the potential to distinguish between Mn(II) oxidation pathways in nature, providing a way to determine which groups of Mn(II) oxidizers may be

New insight of high temperature oxidation on self-exfoliation capability of graphene oxide.

PubMed

Liu, Yuhang; Zeng, Jie; Han, Di; Wu, Kai; Yu, Bowen; Chai, Songgang; Chen, Feng; Fu, Qiang

2018-05-04

The preparation of graphene oxide (GO) via Hummers method is usually divided into two steps: low temperature oxidation at 35 °C (step I oxidation) and high temperature oxidation at 98 °C (step II oxidation). However, the effects of these two steps on the exfoliation capability and chemical structure of graphite oxide remain unclear. In this study, both the functional group content of graphite oxide and the entire evolution of interlayer spacing were investigated during the two steps. Step I oxidation is a slowly inhomogeneous oxidation step to remove unoxidized graphite flakes. The prepared graphite oxide can be easily self-exfoliated but contains a lot of organic sulfur. During the first 20 min of step II oxidation, the majority of organic sulfur can be efficiently removed and graphite oxide still remains a good exfoliation capability due to sharp increasing of carboxyl groups. However, with a longer oxidation time at step II oxidation, the decrease of organic sulfur content is slowed down apparently but without any carboxyl groups forming, then graphite oxide finally loses self-exfoliation capability. It is concluded that a short time of step II oxidation can produce purer and ultralarge GO sheets via self-exfoliation. The pure GO is possessed with better thermal stability and liquid crystal behavior. Besides, reduced GO films prepared from step II oxidation show better mechanical and electric properties after reducing compared with that obtained only via step I oxidation.

New insight of high temperature oxidation on self-exfoliation capability of graphene oxide

NASA Astrophysics Data System (ADS)

Liu, Yuhang; Zeng, Jie; Han, Di; Wu, Kai; Yu, Bowen; Chai, Songgang; Chen, Feng; Fu, Qiang

2018-05-01

The preparation of graphene oxide (GO) via Hummers method is usually divided into two steps: low temperature oxidation at 35 °C (step I oxidation) and high temperature oxidation at 98 °C (step II oxidation). However, the effects of these two steps on the exfoliation capability and chemical structure of graphite oxide remain unclear. In this study, both the functional group content of graphite oxide and the entire evolution of interlayer spacing were investigated during the two steps. Step I oxidation is a slowly inhomogeneous oxidation step to remove unoxidized graphite flakes. The prepared graphite oxide can be easily self-exfoliated but contains a lot of organic sulfur. During the first 20 min of step II oxidation, the majority of organic sulfur can be efficiently removed and graphite oxide still remains a good exfoliation capability due to sharp increasing of carboxyl groups. However, with a longer oxidation time at step II oxidation, the decrease of organic sulfur content is slowed down apparently but without any carboxyl groups forming, then graphite oxide finally loses self-exfoliation capability. It is concluded that a short time of step II oxidation can produce purer and ultralarge GO sheets via self-exfoliation. The pure GO is possessed with better thermal stability and liquid crystal behavior. Besides, reduced GO films prepared from step II oxidation show better mechanical and electric properties after reducing compared with that obtained only via step I oxidation.

Poly[(ethylene oxide)-co-(methylene ethylene oxide)]: A hydrolytically-degradable poly(ethylene oxide) platform.

PubMed

Lundberg, Pontus; Lee, Bongjae F; van den Berg, Sebastiaan A; Pressly, Eric D; Lee, Annabelle; Hawker, Craig J; Lynd, Nathaniel A

2012-11-20

A facile method for imparting hydrolytic degradability to poly(ethylene oxide) (PEO), compatible with current PEGylation strategies, is presented. By incorporating methylene ethylene oxide (MEO) units into the parent PEO backbone, complete degradation was defined by the molar incorporation of MEO, and the structure of the degradation byproducts was consistent with an acid-catalyzed vinyl-ether hydrolysis mechanism. The hydrolytic degradation of poly[(ethylene oxide)-co-(methylene ethylene oxide)] was pH-sensitive, with degradation at pH 5 being significantly faster than at pH 7.4 at 37 °C in PBS buffer while long-term stability could be obtained in either the solid-state or at pH 7.4 at 6 °C.

The impact of sedimentary coatings on the diagenetic Nd flux

NASA Astrophysics Data System (ADS)

Abbott, April N.; Haley, Brian A.; McManus, James

2016-09-01

Because ocean circulation impacts global heat transport, understanding the relationship between deep ocean circulation and climate is important for predicting the ocean's role in climate change. A common approach to reconstruct ocean circulation patterns employs the neodymium isotope compositions of authigenic phases recovered from marine sediments. In this approach, mild chemical extractions of these phases is thought to yield information regarding the εNd of the bottom waters that are in contact with the underlying sediment package. However, recent pore fluid studies present evidence for neodymium cycling within the upper portions of the marine sediment package that drives a significant benthic flux of neodymium to the ocean. This internal sedimentary cycling has the potential to obfuscate any relationship between the neodymium signature recovered from the authigenic coating and the overlying neodymium signature of the seawater. For this manuscript, we present sedimentary leach results from three sites on the Oregon margin in the northeast Pacific Ocean. Our goal is to examine the potential mechanisms controlling the exchange of Nd between the sedimentary package and the overlying water column, as well as the relationship between the εNd composition of authigenic sedimentary coatings and that of the pore fluid. In our comparison of the neodymium concentrations and isotope compositions from the total sediment, sediment leachates, and pore fluid we find that the leachable components account for about half of the total solid-phase Nd, therefore representing a significant reservoir of reactive Nd within the sediment package. Based on these and other data, we propose that sediment diagenesis determines the εNd of the pore fluid, which in turn controls the εNd of the bottom water. Consistent with this notion, despite having 1 to 2 orders of magnitude greater Nd concentration than the bottom water, the pore fluid is still <0.001% of the total Nd reservoir in the

Photo-oxidation catalysts

DOEpatents

Pitts, J Roland [Lakewood, CO; Liu, Ping [Irvine, CA; Smith, R Davis [Golden, CO

2009-07-14

Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.

Separate Nitrite, Nitric Oxide, and Nitrous Oxide Reducing Fractions from Pseudomonas perfectomarinus

PubMed Central

Payne, W. J.; Riley, P. S.; Cox, C. D.

1971-01-01

Pseudomonas perfectomarinus was found to grow anaerobically at the expense of nitrate, nitrite, or nitrous oxide but not chlorate or nitric oxide. In several repetitive experiments, anaerobic incubation in culture media containing nitrate revealed that an average of 82% of the cells in aerobically grown populations were converted to the capacity for respiration of nitrate. Although they did not form colonies under these conditions, the bacteria synthesized the denitrifying enzymes within 3 hr in the absence of oxygen or another acceptable inorganic oxidant. This was demonstrated by the ability, after anaerobic incubation, of cells and of extracts to reduce nitrite, nitric oxide, and nitrous oxide to nitrogen. From crude extracts of cells grown on nitrate, nitrite, or nitrous oxide, separate complex fractions were obtained that utilized reduced nicotinamide adenine dinucleotide as the source of electrons for the reduction of (i) nitrite to nitric oxide, (ii) nitric oxide to nitrous oxide, and (iii) nitrous oxide to nitrogen. Gas chromatographic analyses revealed that each of these fractions reduced only one of the nitrogenous oxides. PMID:4324803

Methodology for the effective stabilization of tin-oxide-based oxidation/reduction catalysts

NASA Technical Reports Server (NTRS)

Jordan, Jeffrey D. (Inventor); Schryer, David R. (Inventor); Leighty, Bradley D. (Inventor); Watkins, Anthony N. (Inventor); Summers, Jerry C. (Inventor); Davis, Patricia P. (Inventor); Oglesby, Donald M. (Inventor); Schryer, Jacqueline L. (Inventor); Gulati, Suresh T. (Inventor)

2011-01-01

The invention described herein involves a novel approach to the production of oxidation/reduction catalytic systems. The present invention serves to stabilize the tin oxide reducible metal-oxide coating by co-incorporating at least another metal-oxide species, such as zirconium. In one embodiment, a third metal-oxide species is incorporated, selected from the group consisting of cerium, lanthanum, hafnium, and ruthenium. The incorporation of the additional metal oxide components serves to stabilize the active tin-oxide layer in the catalytic process during high-temperature operation in a reducing environment (e.g., automobile exhaust). Moreover, the additional metal oxides are active components due to their oxygen-retention capabilities. Together, these features provide a mechanism to extend the range of operation of the tin-oxide-based catalyst system for automotive applications, while maintaining the existing advantages.

X-ray Absorption Study of Graphene Oxide and Transition Metal Oxide Nanocomposites.

PubMed

Gandhiraman, Ram P; Nordlund, Dennis; Javier, Cristina; Koehne, Jessica E; Chen, Bin; Meyyappan, M

2014-08-14

The surface properties of the electrode materials play a crucial role in determining the performance and efficiency of energy storage devices. Graphene oxide and nanostructures of 3d transition metal oxides were synthesized for construction of electrodes in supercapacitors, and the electronic structure and oxidation states were probed using near-edge X-ray absorption fine structure. Understanding the chemistry of graphene oxide would provide valuable insight into its reactivity and properties as the graphene oxide transformation to reduced-graphene oxide is a key step in the synthesis of the electrode materials. Polarized behavior of the synchrotron X-rays and the angular dependency of the near-edge X-ray absorption fine structures (NEXAFS) have been utilized to study the orientation of the σ and π bonds of the graphene oxide and graphene oxide-metal oxide nanocomposites. The core-level transitions of individual metal oxides and that of the graphene oxide nanocomposite showed that the interaction of graphene oxide with the metal oxide nanostructures has not altered the electronic structure of either of them. As the restoration of the π network is important for good electrical conductivity, the C K edge NEXAFS spectra of reduced graphene oxide nanocomposites confirms the same through increased intensity of the sp 2 -derived unoccupied states π* band. A pronounced angular dependency of the reduced sample and the formation of excitonic peaks confirmed the formation of extended conjugated network.

A niobium oxide-tantalum oxide selector-memristor self-aligned nanostack

NASA Astrophysics Data System (ADS)

Diaz Leon, Juan J.; Norris, Kate J.; Yang, J. Joshua; Sevic, John F.; Kobayashi, Nobuhiko P.

2017-03-01

The integration of nonlinear current-voltage selectors and bi-stable memristors is a paramount step for reliable operation of crossbar arrays. In this paper, the self-aligned assembly of a single nanometer-scale device that contains both a selector and a memristor is presented. The two components (i.e., selector and memristor) are vertically assembled via a self-aligned fabrication process combined with electroforming. In designing the device, niobium oxide and tantalum oxide are chosen as materials for selector and memristor, respectively. The formation of niobium oxide is visualized by exploiting the self-limiting reaction between niobium and tantalum oxide; crystalline niobium (di)oxide forms at the interface between metallic niobium and tantalum oxide via electrothermal heating, resulting in a niobium oxide selector self-aligned to a tantalum oxide memristor. A steady-state finite element analysis is used to assess the electrothermal heating expected to occur in the device. Current-voltage measurements and structural/chemical analyses conducted for the virgin device, the electroforming process, and the functional selector-memristor device are presented. The demonstration of a self-aligned, monolithically integrated selector-memristor device would pave a practical pathway to various circuits based on memristors attainable at manufacturing scales.

Simultaneous removal of nitrogen oxides and sulfur oxides from combustion gases

DOEpatents

Clay, David T.; Lynn, Scott

1976-10-19

A process for the simultaneous removal of sulfur oxides and nitrogen oxides from power plant stack gases comprising contacting the stack gases with a supported iron oxide catalyst/absorbent in the presence of sufficient reducing agent selected from the group consisting of carbon monoxide, hydrogen, and mixtures thereof, to provide a net reducing atmosphere in the SO.sub.x /NO.sub.x removal zone. The sulfur oxides are removed by absorption substantially as iron sulfide, and nitrogen oxides are removed by catalytic reduction to nitrogen and ammonia. The spent iron oxide catalyst/absorbent is regenerated by oxidation and is recycled to the contacting zone. Sulfur dioxide is also produced during regeneration and can be utilized in the production of sulfuric acid and/or sulfur.

Gadolinium oxide decorated multiwalled carbon nanotube/tridoped titania nanocomposites for improved dye degradation under simulated solar light irradiation

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

Mamba, Gcina; Nanotechnology and Water Sustainability Research Unit, College of Engineering, Science and Technology, University of South Africa Florida Science Campus, 1709 Florida; Mbianda, Xavier Yangkou

2016-03-15

Graphical abstract: Illustration of the collaborative effect between MWCNT-Gd and Gd,N,S-TiO{sub 2} towards degradation of AB 74. - Highlights: • MWCNT-Gd/tridoped titania was successfully prepared via a sol-gel method. • XPS revealed the presence of Ti, C, O, S, N and Gd in MWCNT-Gd/Gd,N,S-TiO{sub 2}. • MWCNT-Gd/Gd,N,S-TiO{sub 2} displayed 100% degradation of acid blue 74 in 150 min. • Over 60% TOC removal by MWCNT-Gd/Gd,N,S-TiO{sub 2}. - Abstract: Neodymium/gadolinium/europium, nitrogen and sulphur tridoped titania (Nd/Gd/Eu, N,S-TiO{sub 2}) was hybridised with pre-synthesised gadolinium oxide decorated multiwalled carbon nanotubes (MWCNT-Gd) using a sol–gel method. Subsequent to drying and calcination, composite photocatalysts: MWCNT-Gd/Nd,N,S-TiO{submore » 2}, MWCNT-Gd/Gd,N,S-TiO{sub 2} and MWCNT-Gd/Eu,N,S-TiO{sub 2}, were obtained and characterised using TEM, SEM-EDX, UV–vis, XPS, XRD and FT-IR. Acid blue 74 (AB74) was used as a model dye to investigate the photocatalytic degradation properties of the prepared materials under simulated solar light irradiation. Coupling the different tridoped titania with MWCNT-Gd enhanced their activity compared to MWCNT/TiO{sub 2}, MWCNT-Gd/TiO{sub 2} and MWCNT/Gd,N,S-TiO{sub 2}. MWCNT-Gd/Gd,N,S-TiO{sub 2} showed the highest activity towards AB74 degradation reaching 100% decolourisation after 150 min of irradiation. Total organic carbon analysis revealed that over 50% of the AB74 molecules were completely mineralised after 180 min of irradiation in the presence of MWCNT-Gd/Gd,N,S-TiO{sub 2}.« less

Structural Characterization of Oxidized Glycerophosphatidylserine: Evidence of Polar Head Oxidation

NASA Astrophysics Data System (ADS)

Maciel, Elisabete; da Silva, Raquel Nunes; Simões, Cláudia; Domingues, Pedro; Domingues, M. Rosário M.

2011-10-01

Non-oxidized phosphatidylserine (PS) is known to play a key role in apoptosis but there is considerable research evidence suggesting that oxidized PS also plays a role in this event, leading to the increasing interest in studying PS oxidative modifications. In this work, different PS (1-palmitoyl-2-linoleoyl-sn-glycero-3-phospho-L-serine (PLPS), 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS), and 1,2-dipalmitoyl-sn-glycero-3-phospho-L-serine (DPPS) were oxidized in vitro by hydroxyl radical, generated under Fenton reaction conditions, and the reactions were monitored by ESI-MS in negative mode. Oxidation products were then fractionated by thin layer chromatography (TLC) and characterized by tandem mass spectrometry (MS/MS). This approach allowed the identification of hydroxyl, peroxy, and keto derivatives due to oxidation of unsaturated fatty acyl chains. Oxidation products due to oxidation of serine polar head were also identified. These products, with lower molecular weight than the non-modified PS, were identified as [M - 29 - H]- (terminal acetic acid), [M - 30 - H]- (terminal acetamide), [M - 13 - H]- (terminal hydroperoxyacetaldehyde), and [M - 13 - H]- (terminal hydroxyacetaldehyde plus hydroxy fatty acyl chain). Phosphatidic acid was also formed in these conditions. These findings confirm the oxidation of the serine polar head induced by the hydroxyl radical. The identification of these modifications may be a valuable tool to evaluate phosphatidylserine alteration under physiopathologic conditions and also to help understand the biological role of phosphatidylserine oxidation in the apoptotic process and other biological functions.

21 CFR 172.808 - Copolymer condensates of ethylene oxide and propylene oxide.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Copolymer condensates of ethylene oxide and... ethylene oxide and propylene oxide. Copolymer condensates of ethylene oxide and propylene oxide may be... percent aqueous solution. (2) α-Hydro-omega-hydroxy-poly (oxy-ethylene)poly(oxypropylene)-(53-59 moles...

Chronic exposure to iron oxide, chromium oxide, and nickel oxide fumes of metal dressers in a steelworks

PubMed Central

Jones, J. Graham; Warner, C. G.

1972-01-01

Graham Jones, J., and Warner, C. G. (1972).Brit. J. industr. Med.,29, 169-177. Chronic exposure to iron oxide, chromium oxide, and nickel oxide fumes of metal dressers in a steelworks. Occupational and medical histories, smoking habits, respiratory symptoms, chest radiographs, and ventilatory capacities were studied in 14 steelworkers employed as deseamers of steel ingots for periods of up to 16 years. The men were exposed for approximately five hours of each working shift to fume concentrations ranging from 1·3 to 294·1 mg/m3 made up mainly of iron oxide with varying proportions of chromium oxide and nickel oxide. Four of the men, with 14 to 16 years' exposure, showed radiological evidence of pneumoconiosis classified as ILO categories 2 or 3. Of these, two had pulmonary function within the normal range and two had measurable loss of function, moderate in one case and mild in the other. Many observers would diagnose these cases as siderosis but the authors consider that this term should be reserved for cases exposed to pure iron compounds. The correct diagnosis is mixed-dust pneumoconiosis and the loss of pulmonary function is caused by the effects of the mixture of metallic oxides. It is probable that inhalation of pure iron oxide does not cause fibrotic pulmonary changes, whereas the inhalation of iron oxide plus certain other substances obviously does. Images PMID:5021996

Oxidation resistant alloys, method for producing oxidation resistant alloys

DOEpatents

Dunning, John S.; Alman, David E.

2002-11-05

A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800 C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800 C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700 C. at a low cost

Imprinted Oxide and MIP/Oxide Hybrid Nanomaterials for Chemical Sensors †.

PubMed

Afzal, Adeel; Dickert, Franz L

2018-04-20

The oxides of transition, post-transition and rare-earth metals have a long history of robust and fast responsive recognition elements for electronic, optical, and gravimetric devices. A wide range of applications successfully utilized pristine or doped metal oxides and polymer-oxide hybrids as nanostructured recognition elements for the detection of biologically relevant molecules, harmful organic substances, and drugs as well as for the investigative process control applications. An overview of the selected recognition applications of molecularly imprinted sol-gel phases, metal oxides and hybrid nanomaterials composed of molecularly imprinted polymers (MIP) and metal oxides is presented herein. The formation and fabrication processes for imprinted sol-gel layers, metal oxides, MIP-coated oxide nanoparticles and other MIP/oxide nanohybrids are discussed along with their applications in monitoring bioorganic analytes and processes. The sensor characteristics such as dynamic detection range and limit of detection are compared as the performance criterion and the miniaturization and commercialization possibilities are critically discussed.

Imprinted Oxide and MIP/Oxide Hybrid Nanomaterials for Chemical Sensors †

PubMed Central

2018-01-01

The oxides of transition, post-transition and rare-earth metals have a long history of robust and fast responsive recognition elements for electronic, optical, and gravimetric devices. A wide range of applications successfully utilized pristine or doped metal oxides and polymer-oxide hybrids as nanostructured recognition elements for the detection of biologically relevant molecules, harmful organic substances, and drugs as well as for the investigative process control applications. An overview of the selected recognition applications of molecularly imprinted sol-gel phases, metal oxides and hybrid nanomaterials composed of molecularly imprinted polymers (MIP) and metal oxides is presented herein. The formation and fabrication processes for imprinted sol-gel layers, metal oxides, MIP-coated oxide nanoparticles and other MIP/oxide nanohybrids are discussed along with their applications in monitoring bioorganic analytes and processes. The sensor characteristics such as dynamic detection range and limit of detection are compared as the performance criterion and the miniaturization and commercialization possibilities are critically discussed. PMID:29677107

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

NASA Astrophysics Data System (ADS)

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

2015-11-01

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

Investigation of Mixed Oxide Catalysts for NO Oxidation

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

Szanyi, Janos; Karim, Ayman M.; Pederson, Larry R.

2014-12-09

The oxidation of engine-generated NO to NO2 is an important step in the reduction of NOx in lean engine exhaust because NO2 is required for the performance of the LNT technology [2], and it enhances the activities of ammonia selective catalytic reduction (SCR) catalysts [1]. In particular, for SCR catalysts an NO:NO2 ratio of 1:1 is most effective for NOx reduction, whereas for LNT catalysts, NO must be oxidized to NO2 before adsorption on the storage components. However, NO2 typically constitutes less than 10% of NOx in lean exhaust, so catalytic oxidation of NO is essential. Platinum has been foundmore » to be especially active for NO oxidation, and is widely used in DOC and LNT catalysts. However, because of the high cost and poor thermal durability of Pt-based catalysts, there is substantial interest in the development of alternatives. The objective of this project, in collaboration with partner General Motors, is to develop mixed metal oxide catalysts for NO oxidation, enabling lower precious metal usage in emission control systems. [1] M. Koebel, G. Madia, and M. Elsener, Catalysis Today 73, 239 (2002). [2] C. H. Kim, G. S. Qi, K. Dahlberg, and W. Li, Science 327, 1624 (2010).« less

Oxidation of artificial sweetener sucralose by advanced oxidation processes: a review.

PubMed

Sharma, Virender K; Oturan, Mehmet; Kim, Hyunook

2014-01-01

Sucralose, a chlorinated carbohydrate, has shown its increased use as an artificial sweetener and persistently exists in wastewater treatment plant effluents and aquatic environment. This paper aims to review possible degradation of sucralose and related carbohydrates by biological, electrochemical, chemical, and advanced oxidation processes. Biodegradation of sucralose in waterworks did not occur significantly. Electrochemical oxidation of carbohydrates may be applied to seek degradation of sucralose. The kinetics of the oxidation of sucralose and the related carbohydrates by different oxidative species is compared. Free chlorine, ozone, and ferrate did not show any potential to degrade sucralose in water. Advanced oxidation processes, generating highly strong oxidizing agent hydroxyl radicals ((•)OH), have demonstrated effectiveness in transforming sucralose in water. The mechanism of oxidation of sucralose by (•)OH is briefly discussed.

Improved Understanding of In Situ Chemical Oxidation Contaminant Oxidation Kinetics

DTIC Science & Technology

2007-12-01

natural oxidant demand •OH hydroxide radical Ox oxidant O3 ozone PCE perchloroethylene HSO5− peroxymonosulfate PNDA p...properties (e.g., soil mineralogy , natural carbon content) affect oxidant mobility and stability in the subsurface, and develop a standardized natural...chlorinated ethenes For contaminant oxidation by activated S2O82−, it is more difficult to develop a general description of kobs vs. T because there are

Oxidation of nitroxyl anion to nitric oxide by copper ions

PubMed Central

Nelli, Silvia; Hillen, Mark; Buyukafsar, Kansu; Martin, William

2000-01-01

This study made use of a nitric oxide-sensitive electrode to examine possible means of generating nitric oxide from nitroxyl anion (NO−) released upon the decomposition of Angeli's salt. Our results show that copper ions (from CuSO4) catalyze the rapid and efficient oxidation of nitroxyl to nitric oxide. Indeed, the concentrations of copper required to do so (0.1–100 μM) are roughly 100-times lower than those required to generate equivalent amounts of nitric oxide from S-nitroso-N-acetyl-D,L-penicillamine (SNAP). Experiments with ascorbate (1 mM), which reduces Cu2+ ions to Cu+, and with the Cu2+ chelators, EDTA and cuprizone, and the Cu+ chelator, neocuproine, each at 1 mM, suggest that the oxidation is catalyzed by copper ions in both valency states. Some compounds containing other transition metals, i.e. methaemoglobin, ferricytochrome c and Mn(III)TMPyP, were much less efficient than CuSO4 in catalyzing the formation of nitric oxide from nitroxyl, while FeSO4, FeCl3, MnCl2, and ZnSO4 were inactive. Of the copper containing enzymes examined, Cu-Zn superoxide dismutase and ceruloplasmin were weak generators of nitric oxide from nitroxyl, even at concentrations (2500 and 30 u ml−1, respectively) vastly greater than are present endogenously. Two others, ascorbate oxidase (10 u ml−1) and tyrosinase (250 u ml−1) were inactive. Our findings suggest that a copper-containing enzyme may be responsible for the rapid oxidation of nitroxyl to nitric oxide by cells, but the identity of such an enzyme remains elusive. PMID:10991931

Reproductive Benefit of Oxidative Damage: An Oxidative Stress “Malevolence”?

PubMed Central

Poljsak, B.; Milisav, I.; Lampe, T.; Ostan, I.

2011-01-01

High levels of reactive oxygen species (ROS) compared to antioxidant defenses are considered to play a major role in diverse chronic age-related diseases and aging. Here we present an attempt to synthesize information about proximate oxidative processes in aging (relevant to free radical or oxidative damage hypotheses of aging) with an evolutionary scenario (credited here to Dawkins hypotheses) involving tradeoffs between the costs and benefits of oxidative stress to reproducing organisms. Oxidative stress may be considered a biological imperfection; therefore, the Dawkins' theory of imperfect adaptation of beings to environment was applied to the role of oxidative stress in processes like famine and infectious diseases and their consequences at the molecular level such as mutations and cell signaling. Arguments are presented that oxidative damage is not necessarily an evolutionary mistake but may be beneficial for reproduction; this may prevail over its harmfulness to health and longevity in evolution. Thus, Dawkins' principle of biological “malevolence” may be an additional biological paradigm for explaining the consequences of oxidative stress. PMID:21969876

Laser intervention on trabeculo-Descemet's membrane after resistant viscocanalostomy: Selective 532 nm gonioreconditioning or conventional 1064 nm neodymium-doped yttrium aluminum garnet laser goniopuncture?

PubMed Central

Sabur, Huri; Baykara, Mehmet; Can, Basak

2016-01-01

Purpose: To compare the results of conventional 1064 nm neodymium-doped yttrium-aluminum garnet laser goniopuncture (Nd:YAG-GP) and selective 532 nm Nd:YAG laser (selective laser trabeculoplasty [SLT]) gonioreconditioning (GR) on trabeculo-Descemet's membrane in eyes resistant to viscocanalostomy surgery. Methods: Thirty-eight eyes of 35 patients who underwent laser procedure after successful viscocanalostomy surgery were included in the study. When postoperative intraocular pressure (IOP) was above the individual target, the eyes were scheduled for laser procedure. Nineteen eyes underwent 532 nm SLT-GR (Group 1), and the remaining 19 eyes underwent conventional 1064 nm Nd:YAG-GP (Group 2). IOPs before and after laser (1 week, 1 month, 3 months, 6 months, 1 year, and last visit), follow-up periods, number of glaucoma medications, and complications were recorded for both groups. Results: Mean times from surgery to laser procedures were 17.3 ± 9.6 months in Group 1 and 13.0 ± 11.4 months in Group 2. Mean IOPs before laser procedures were 21.2 ± 1.7 mmHg in Group 1 and 22.8 ± 1.9 mmHg in Group 2 (P = 0.454). Postlaser IOP measurements of Group 1 were 12.1 ± 3.4 mmHg and 13.8 ± 1.7 mmHg in the 1st week and last visit, respectively; in Group 2, these measurements were 13.6 ± 3.7 mmHg and 14.9 ± 4.8 mmHg, respectively. There were statistically significant differences (P < 0.001) in IOP reduction at all visits in both groups; the results of the two groups were similar (P > 0.05). Mean follow-up was 16.6 ± 6.4 months after SLT-GR and 18.9 ± 11.2 months after Nd:YAG-GP. Conclusions: While conventional Nd:YAG-GP and SLT-GR, a novel procedure, are both effective choices in eyes resistant to viscocanalostomy, there are fewer complications with SLT-GR. SLT-GR can be an alternative to conventional Nd:YAG-GP. PMID:27688277

Nanostructured transition metal oxides useful for water oxidation catalysis

DOEpatents

Frei, Heinz M; Jiao, Feng

2013-12-24

The present invention provides for a composition comprising a nanostructured transition metal oxide capable of oxidizing two H.sub.2O molecules to obtain four protons. In some embodiments of the invention, the composition further comprises a porous matrix wherein the nanocluster of the transition metal oxide is embedded on and/or in the porous matrix.

Oxidation resistant alloys, method for producing oxidation resistant alloys

DOEpatents

Dunning, John S.; Alman, David E.

2002-11-05

A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800.degree. C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800.degree. C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700.degree. C. at a low cost

The Clinical and Histological Effect of a Low-Fluence Q-Switched 1,064-nm Neodymium: Yttrium-Aluminum-Garnet Laser for the Treatment of Melasma and Solar Lentigenes in Asians: Prospective, Randomized, and Split-Face Comparative Study.

PubMed

Kaminaka, Chikako; Furukawa, Fukumi; Yamamoto, Yuki

2017-09-01

The low-fluence Q-switched 1,064-nm neodymium:yttrium-aluminum-garnet laser (QSNYL) is popular for melasma treatment among Asians. This study was to evaluate the clinical and histological effects of the low-fluence QSNYL for treatment of melasma and solar lentigenes. In this randomized split-face clinical study, 22 patients with melasma or solar lentigo received low-fluence QSNYL weekly for 10 sessions on one cheek. The treatment efficacy was determined by Mexameter skin colorimetry, physician and patient assessment, and by evaluating histological changes. The treated sides had statistically significant reductions in the melanin and erythema indices (EI); 50.0% of melasma and 62.5% of solar lentigo patients had >50% clearance after the final treatment. The increased EI, vascularity, and mast cell activity in patients with melasma and large-sized solar lentigo showed no improvement. The recurrence rates were 16.7% and 12.7% for melasma and solar lentigo, respectively. Postinflammatory hyperpigmentation developed in 1 patient, but no serious side effects were noted. Low-fluence QSNYL is effective in treating melasma and small type solar lentigo in Asians. The authors' study also demonstrated that lesion thickness, vascularity, and mast cell activity can be used to predict the efficacy of the treatment of these lesions.

UV Induced Oxidation of Nitric Oxide

NASA Technical Reports Server (NTRS)

Parrish, Clyde, F. (Inventor); Luecke, Dale E. (Inventor)

2007-01-01

Nitric oxide in a gaseous stream is converted to nitrogen dioxide using oxidizing species generated at least in part using in situ UV radiation sources. The sources of the oxidizing species include oxygen and/or hydrogen peroxide. The oxygen may be a component of the gaseous stream or added to the gaseous stream, preferably near a UV radiation source, and is converted to ozone by the UV irradiation. The hydrogen peroxide is decomposed through a combination of vaporization and UV irradiation. The hydrogen peroxide is preferably stored at stable concentration levels, i.e., approximately 50% by volume and increased in concentration in a continuous process preceding vaporization within the flow channel of the gaseous stream and in the presence of the UV radiation sources.

Some Properties of Beryllium Oxide and Beryllium Oxide - Columbium Ceramals

NASA Technical Reports Server (NTRS)

Robards, C F; Gangler, J J

1951-01-01

High-temperature tensile and thermal-shock investigations were conducted on beryllium oxide and beryllium oxide plus columbium metal additions. X-ray diffraction and metallographic results are given. The tensile strength of 6150 pounds per square inch for beryllium oxide at 1800 degrees F compared favorably with the zirconia bodies previously tested. Additions of 2, 5, 8, 10, 12, and 15 percent by weight of columbium metal failed to improve the shock resistance over that of pure beryllium oxide.

Partial oxidation catalyst

DOEpatents

Krumpelt, Michael; Ahmed, Shabbir; Kumar, Romesh; Doshi, Rajiv

2000-01-01

A two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion. The dehydrogenation portion is a group VIII metal and the oxide-ion conducting portion is selected from a ceramic oxide crystallizing in the fluorite or perovskite structure. There is also disclosed a method of forming a hydrogen rich gas from a source of hydrocarbon fuel in which the hydrocarbon fuel contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion at a temperature not less than about 400.degree. C. for a time sufficient to generate the hydrogen rich gas while maintaining CO content less than about 5 volume percent. There is also disclosed a method of forming partially oxidized hydrocarbons from ethanes in which ethane gas contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion for a time and at a temperature sufficient to form an oxide.

[An investigation of lanthanum and other metals levels in blood, urine and hair among residents in the rare earth mining area of a city in China].

PubMed

Bao, T M; Tian, Y; Wang, L X; Wu, T; Lu, L N; Ma, H Y; Wang, L

2018-02-20

Objective: To investigate the levels of lanthanum, cerium, praseodymium, and neodymium in the blood, urine, and hair samples from residents in the rare earth mining area of a city in China, and to provide a scientific basis for the control of rare earth pollution and the protection of population health. Methods: A total of 147 residents who had lived in the rare earth mining area of a city for a long time were selected as the exposure group, and 108 residents in Guyang County of this city who lived 91 km away from the rare earth mining area were selected as the control group. Blood, urine, and hair samples were collected from the residents in both groups. Inductively coupled plasma mass spectrometry was used to determine the content of lanthanum, cerium, praseodymium, and neodymium in blood, urine, and hair samples. Results: In the exposure group, the median levels of lanthanum, cerium, praseodymium, and neodymium were 0.854, 1.724, 0.132, and 0.839 μg/L, respectively, in blood samples, 0.420, 0.920, 0.055, and 0.337 μg/L, respectively, in urine samples, and 0.052, 0.106, 0.012, and 0.045 μg/g, respectively, in hair samples. The exposure group had significantly higher levels of the four rare earth elements in blood, urine, and hair samples than the control group ( P <0.01) . Conclusion: The residents in the rare earth mining area of this city have higher content of lanthanum, cerium, praseodymium, and neodymium in blood, urine, and hair than those in the non-mining area; the content of cerium is highest, followed by lanthanum, neodymium, and praseodymium.

Growth control of the oxidation state in vanadium oxide thin films

DOE PAGES

Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; ...

2014-12-05

Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research, but also technological applications that utilize the subtle change in the physical properties originating from the metalinsulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase puremore » epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V₂⁺²O₃, V⁺⁴O₂, and V₂⁺⁵O₅. A well pronounced MIT was only observed in VO₂ films grown in a very narrow range of oxygen partial pressure P(O₂). The films grown either in lower (< 10 mTorr) or higher P(O₂) (> 25 mTorr) result in V₂O₃ and V₂O₅ phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO₂ thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an 3 improved MIT behavior.« less

Growth control of the oxidation state in vanadium oxide thin films

NASA Astrophysics Data System (ADS)

Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

2014-12-01

Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V2 + 3 O 3 , V + 4 O 2 , and V2 + 5 O 5 . A well pronounced MIT was only observed in VO2 films grown in a very narrow range of oxygen partial pressure P(O2). The films grown either in lower (<10 mTorr) or higher P(O2) (>25 mTorr) result in V2O3 and V2O5 phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO2 thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.

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

Okamura, M., E-mail: okamura@bnl.gov; Nishina Center for Accelerator-Based Science, RIKEN, Saitama; Palm, K.

Calcium and lithium ion beams are required by NASA Space Radiation Laboratory at Brookhaven National Laboratory to simulate the effects of cosmic radiation. To identify the difficulties in providing such highly reactive materials as laser targets, both species were experimentally tested. Plate shaped lithium and calcium targets were fabricated to create ablation plasmas with a 6 ns 1064 nm neodymium-doped yttrium aluminum garnet laser. We found significant oxygen contamination in both the Ca and Li high charge state beams due to the rapid oxidation of the surfaces. A large spot size, low power density laser was used to create lowmore » charge state beams without scanning the targets. The low charge state Ca beam did not have any apparent oxygen contamination, showing the potential to clean the target entirely of oxide with a low power beam once in the chamber. The Li target was clearly still oxidizing in the chamber after each low power shot. To measure the rate of oxidation, we shot the low power laser at the target repeatedly at 10 s, 30 s, 60 s, and 120 s interval lengths, showing a linear relation between the interval time and the amount of oxygen in the beam.« less

Oxidation stress evolution and relaxation of oxide film/metal substrate system

NASA Astrophysics Data System (ADS)

Dong, Xuelin; Feng, Xue; Hwang, Keh-Chih

2012-07-01

Stresses in the oxide film/metal substrate system are crucial to the reliability of the system at high temperature. Two models for predicting the stress evolution during isothermal oxidation are proposed. The deformation of the system is depicted by the curvature for single surface oxidation. The creep strain of the oxide and metal, and the lateral growth strain of the oxide are considered. The proposed models are compared with the experimental results in literature, which demonstrates that the elastic model only considering for elastic strain gives an overestimated stress in magnitude, but the creep model is consistent with the experimental data and captures the stress relaxation phenomenon during oxidation. The effects of the parameter for the lateral growth strain rate are also analyzed.

Role of oxidative stress and nitric oxide in atherothrombosis

PubMed Central

Lubos, Edith; Handy, Diane E.; Loscalzo, Joseph

2008-01-01

During the last decade basic and clinical research has highlighted the central role of reactive oxygen species (ROS) in cardiovascular disease. Enhanced production or attenuated degradation of ROS leads to oxidative stress, a process that affects endothelial and vascular function, and contributes to vascular disease. Nitric oxide (NO), a product of the normal endothelium, is a principal determinant of normal endothelial and vascular function. In states of inflammation, NO production by the vasculature increases considerably and, in conjunction with other ROS, contributes to oxidative stress. This review examines the role of oxidative stress and NO in mechanisms of endothelial and vascular dysfunction with an emphasis on atherothrombosis. PMID:18508590

Oxidized film structure and method of making epitaxial metal oxide structure

DOEpatents

Gan, Shupan [Richland, WA; Liang, Yong [Richland, WA

2003-02-25

A stable oxidized structure and an improved method of making such a structure, including an improved method of making an interfacial template for growing a crystalline metal oxide structure, are disclosed. The improved method comprises the steps of providing a substrate with a clean surface and depositing a metal on the surface at a high temperature under a vacuum to form a metal-substrate compound layer on the surface with a thickness of less than one monolayer. The compound layer is then oxidized by exposing the compound layer to essentially oxygen at a low partial pressure and low temperature. The method may further comprise the step of annealing the surface while under a vacuum to further stabilize the oxidized film structure. A crystalline metal oxide structure may be subsequently epitaxially grown by using the oxidized film structure as an interfacial template and depositing on the interfacial template at least one layer of a crystalline metal oxide.

Oxidation resistance of silicon ceramics

NASA Technical Reports Server (NTRS)

Yasutoshi, H.; Hirota, K.

1984-01-01

Oxidation resistance, and examples of oxidation of SiC, Si3N4 and sialon are reviewed. A description is given of the oxidation mechanism, including the oxidation product, oxidation reaction and the bubble size. The oxidation reactions are represented graphically. An assessment is made of the oxidation process, and an oxidation example of silicon ceramics is given.

Construction and evaluation of a modular biofilm-forming chamber for microbial recovery of neodymium and semi-continuous biofilm preparation. Tolerance of Serratia sp.N14 on acidic conditions and neutralized aqua regia.

PubMed

Vavlekas, Dimitrios A

2017-02-01

Recovery of neodymium from liquid metallic wastes and scrap leachates is a crucial step for its recycling, which can take place through the immobilized biofilms of Serratia sp. N14. These biofilms are produced in a fermentor vessel with a turnaround time of 10-14 days, which is unacceptable from an economic point of view for an industrial process. This study proposes the construction and evaluation of a modular system, whereby a biofilm-forming chamber is inserted into the continuous biomass outflow of the main chemostat vessel, for an alternative semi-continuous and economic production of biofilm. The activity of the biofilm from the outflow chamber was found to be the same as the one from the main chamber, which was stored in a cold room (4°C), for 9-12 months, depending on a 24 h nucleation step.Moreover, the ability of the biofilm to function in the presence of a leaching agent (aqua regia) or in acidic conditions was also evaluated. The biofilm of the main chamber can remain active even at 50% neutralized aqua regia (pH 3.0), while at acidic conditions, phosphate release of the cells is reduced to 50%. This strain proves to be very tolerant in low pH or high salt concentration solutions. The biofilm produced from the outflow of the main fermentor vessel is of acceptable activity, rather than being disposed.

Growth control of the oxidation state in vanadium oxide thin films

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

Lee, Shinbuhm; Meyer, Tricia L.; Lee, Ho Nyung, E-mail: hnlee@ornl.gov

2014-12-01

Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase puremore » epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V{sub 2}{sup +3}O{sub 3}, V{sup +4}O{sub 2}, and V{sub 2}{sup +5}O{sub 5}. A well pronounced MIT was only observed in VO{sub 2} films grown in a very narrow range of oxygen partial pressure P(O{sub 2}). The films grown either in lower (<10 mTorr) or higher P(O{sub 2}) (>25 mTorr) result in V{sub 2}O{sub 3} and V{sub 2}O{sub 5} phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO{sub 2} thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.« less

Liquid-phase oxidation of cyclohexanone over cerium oxide catalyst

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

Shen, H.C.; Weng, H.S.

Catalytic oxidation of cyclohexanone in the liquid phase with glacial acetic acid as the solvent over cerium oxide was studied between 5 and 15 atm and 98 and 118 {degrees} C in a batch reactor. The products were adipic acid, glutaric acid, succinic acid, caprolactone, carbon oxides, etc. The reaction undergoes a short induction period prior to a rapid reaction regime. In both regimes, the reaction is independent of oxygen pressure when the system pressure is above 10 atm. The induction period is inversely proportional to both of the catalyst weight and cyclohexanone concentration.During the rapid reaction regime, the reactionmore » rate was found to be proportional to the 0.5 power of the catalyst weight and to the 1.5 power of the cyclohexanone concentration. Reaction mechanisms and rate expressions are proposed. The carbon oxides produced in this study were much lower than those previously reported. The cerium oxide catalyst is stable during the reaction.« less

Niche differentiation of ammonia oxidizers and nitrite oxidizers in rice paddy soil.

PubMed

Ke, Xiubin; Angel, Roey; Lu, Yahai; Conrad, Ralf

2013-08-01

The dynamics of populations and activities of ammonia-oxidizing and nitrite-oxidizing microorganisms were investigated in rice microcosms treated with two levels of nitrogen. Different soil compartments (surface, bulk, rhizospheric soil) and roots (young and old roots) were collected at three time points (the panicle initiation, heading and maturity periods) of the season. The population dynamics of bacterial (AOB) and archaeal (AOA) ammonia oxidizers was assayed by determining the abundance (using qPCR) and composition (using T-RFLP and cloning/sequencing) of their amoA genes (coding for a subunit of ammonia monooxygenase), that of nitrite oxidizers (NOB) by quantifying the nxrA gene (coding for a subunit of nitrite oxidase of Nitrobacter spp.) and the 16S rRNA gene of Nitrospira spp. The activity of the nitrifiers was determined by measuring the rates of potential ammonia oxidation and nitrite oxidation and by quantifying the copy numbers of amoA and nxrA transcripts. Potential nitrite oxidation activity was much higher than potential ammonia oxidation activity and was not directly affected by nitrogen amendment demonstrating the importance of ammonia oxidizers as pace makers for nitrite oxidizer populations. Marked differences in the distribution of bacterial and archaeal ammonia oxidizers, and of Nitrobacter-like and Nitrospira-like nitrite oxidizers were found in the different compartments of planted paddy soil indicating niche differentiation. In bulk soil, ammonia-oxidizing bacteria (Nitrosospira and Nitrosomonas) were at low abundance and displayed no activity, but in surface soil their activity and abundance was high. Nitrite oxidation in surface soil was dominated by Nitrospira spp. By contrast, ammonia-oxidizing Thaumarchaeota and Nitrobacter spp. seemed to dominate nitrification in rhizospheric soil and on rice roots. In contrast to soil compartment, the level of N fertilization and the time point of sampling had only little effect on the abundance

Oxidation of Haynes 230 alloy in reduced temperature solid oxide fuel cell environments

NASA Astrophysics Data System (ADS)

Jian, Li; Jian, Pu; Jianzhong, Xiao; Xiaoliang, Qian

Haynes 230 alloy was exposed to reducing and oxidizing environments at 750 °C for 1000 h, simulating the conditions in a reduced temperature solid oxide fuel cell (SOFC). The oxidized specimens were characterized in terms of the oxide morphology, composition and crystal structure. The oxide scale in each environment was identified as Cr 2O 3 with the existence of Cr 2MnO 4. Ni remained metallic in the reducing atmosphere, and NiO was detected in the sample exposed to air. The oxide scale is around 1 μm thick after 1000 h of oxidation in both situations. The area specific resistance (ASR) contributed by the oxide scale is expected less than 0.1 Ω cm 2 after 40,000 h of exposure when a parabolic oxide growth rate is assumed, demonstrating the suitability of the interconnect application of this alloy in the reduced temperature SOFCs.

Improved Understanding of In Situ Chemical Oxidation. Technical Objective I: Contaminant Oxidation Kinetics Contaminant Oxidation Kinetics

DTIC Science & Technology

2009-05-01

methyl tert butyl ether NAPL non-aqueous phase liquid NOD natural oxidant demand •OH hydroxide radical Ox oxidant O3 ozone PCE...and persulfate; and Technical Objective 2, assess how soil properties (e.g., soil mineralogy , natural carbon content) affect oxidant mobility and...to develop a general description of kobs vs. T because there are many reactions that can contribute to the concentration of the reactive intermediate

Ambient temperature NO oxidation over Cr-based amorphous mixed oxide catalysts: effects from the second oxide components

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

Wang, Aiyong; Lin, Bo; Zhang, Hanlei

2017-01-01

Three series of Cr-based mixed oxides (Cr-Co, Cr-Fe, and Cr-Ni oxides) with high specific surface areas and amorphous textures were synthesized using a novel sol-gel method. These mixed oxides, in comparison to their pure metal oxide (CrOx, Co3O4, FeOx and NiO) counterparts, display enhanced performance for catalytic oxidation of low-concentration NO at room temperature. The best performing catalysts achieve 100% NO conversion for ~30 h of operation at a high space velocity of 45,000 ml g-1 h-1. The amorphous structure was found to be critical for these catalysts to maintain high activity and durability. Control of Cr/M (M=Co, Fe andmore » Ni) molar ratio, nitrate precursor decomposition temperature and catalyst calcination temperature was key to the synthesis of these highly active catalysts.« less

Diversity of Mn oxides produced by Mn(II)-oxidizing fungi

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

Santelli, Cara M.; Webb, Samuel M.; Dohnalkova, Alice

Manganese (Mn) oxides are environmentally abundant, highly reactive mineral phases that mediate the biogeochemical cycling of nutrients, contaminants, carbon, and numerous other elements. Despite the belief that microorganisms (specifically bacteria and fungi) are responsible for the majority of Mn oxide formation in the environment, the impact of microbial species, physiology, and growth stage on Mn oxide formation is largely unresolved. Here, we couple microscopic and spectroscopic techniques to characterize the Mn oxides produced by four different species of Mn(II)-oxidizing Ascomycete fungi (Plectosphaerella cucumerina strain DS2psM2a2, Pyrenochaeta sp. DS3sAY3a, Stagonospora sp. SRC1lsM3a, and Acremonium strictum strain DS1bioAY4a) isolated from acid minemore » drainage treatment systems in central Pennsylvania. The site of Mn oxide formation varies greatly among the fungi, including deposition on hyphal surfaces, at the base of reproductive structures (e.g., fruiting bodies), and on envisaged extracellular polymers adjacent to the cell. The primary product of Mn(II) oxidation for all species growing under the same chemical and physical conditions is a nanoparticulate, poorly-crystalline hexagonal birnessite-like phase resembling synthetic d-MnO2. The phylogeny and growth conditions (planktonic versus surface-attached) of the fungi, however, impact the conversion of the initial phyllomanganate to more ordered phases, such as todorokite (A. strictum strain DS1bioAY4a) and triclinic birnessite (Stagonospora sp. SRC1lsM3a). Our findings reveal that the species of Mn(II)-oxidizing fungi impacts the size, morphology, and structure of Mn biooxides, which will likely translate to large differences in the reactivity of the Mn oxide phases.« less

Oxidizer Scoping Studies

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

Chancellor, Christopher John

2016-11-07

The purpose of this report is to present the results of the acceptable knowledge (AK) review of oxidizers present in active waste streams, provide a technical analysis of the oxidizers, and report the results of the scoping study testing. This report will determine the fastest burning oxidizer to be used in the development of a Test Plan for Preparation and Testing of Sorbents Mixed with Oxidizer found in Transuranic Waste (DWT-TP-001). The companion report, DWT-RPT-002, Sorbent Scoping Studies, contains similar information for sorbents identified during the AK review of TRU waste streams. The results of the oxidizer and sorbent scopingmore » studies will be used to inform the QL1 test plan. The QL1 test results will support the development of a basis of knowledge document that will evaluate oxidizing chemicals and sorbents in TRU waste and provide guidance for treatment.« less

Metal oxide-polymer composites

NASA Technical Reports Server (NTRS)

Wellinghoff, Stephen T. (Inventor)

1997-01-01

A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

Metal oxide-polymer composites

NASA Technical Reports Server (NTRS)

Wellinghoff, Stephen T. (Inventor)

1994-01-01

A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

Electronic structure of layered titanate Nd 2Ti 2O 7

NASA Astrophysics Data System (ADS)

Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.

2008-10-01

The electronic structure of the binary titanate Nd 2Ti 2O 7 has been studied by X-ray photoelectron spectroscopy (XPS). Spectral features of the valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Nd 2Ti 2O 7 are determined as αTi = 873.5 and αO = 1042.2 eV. Chemical bonding effects have been discussed with the binding energies differences ΔTi = (BE O 1s - BE Ti 2p 3/2) = 71.5 eV and ΔNd = (BE Nd 3d 5/2 - BE O 1s) = 452.5 eV as key parameters in comparison with those in other titanium- and neodymium-bearing oxides.

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

Corbey, Jordan F.; Rapko, Brian M.; Wang, Zheming

Abstract The crystal structures of americium species containing a common multi-functional phosphine oxide ligand, reported for its ability to extract f elements from acidic solutions, namely 2,6-[Ph2P(O)CH2]2C5H3-NO, L, have finally been determined after over three decades of separations studies involving these species and their surrogates. The molecular compounds Am(L)(NO3)3, Am 1:1, and [Am(L)2(NO3)][NO3]2, Am 2:1, along with their neodymium and europium analogs were synthesized and characterized using single-crystal X-ray crystallography, attenuated total reflectance Fourier transform infrared (ATR) spectroscopy and luminescence spectroscopy to provide a comprehensive comparison with new and known analogous complexes.

Transport and transformation of riverine neodymium isotope and rare earth element signatures in high latitude estuaries: A case study from the Laptev Sea

NASA Astrophysics Data System (ADS)

Laukert, Georgi; Frank, Martin; Bauch, Dorothea; Hathorne, Ed C.; Gutjahr, Marcus; Janout, Markus; Hölemann, Jens

2017-11-01

Marine neodymium (Nd) isotope and rare earth element (REE) compositions are valuable tracers for present and past ocean circulation and continental inputs. Yet their supply via high latitude estuaries is largely unknown. Here we present a comprehensive dissolved Nd isotope (expressed as εNd values) and REE data set together with seawater stable oxygen isotope (δ18O) compositions of samples from the Laptev Sea recovered in two Arctic summers and one winter. The Laptev Sea is a shallow Siberian Shelf sea characterized by extensive river-runoff, sea-ice production and ice transport into the Arctic Ocean. The large variability in εNd (-6 to -17), REE concentrations (16 to 600 pmol/kg for Nd) and REE patterns is controlled by freshwater supply from distinct riverine sources and open ocean Arctic Atlantic Water. Strikingly and contrary to expectations, except for cerium no evidence for significant release of REEs from particulate phases is found, which is attributed to low amounts of suspended particulate matter and high dissolved organic carbon concentrations present in the contributing rivers. Essentially all shelf waters are depleted in light (L)REEs, while the distribution of the heavy REEs shows a deficiency at the surface and a pronounced excess in the bottom layer. This distribution is consistent with REE removal through coagulation of riverine nanoparticles and colloids starting at salinities near 10 and resulting in a drop of all REE concentrations by ∼30%. With increasing salinity preferential LREE removal is observable reaching ∼75% for Nd at a salinity of 34. Although the delayed onset of dissolved REE removal contrasts with most previous observations from other estuarine environments, it agrees remarkably well with results from recent experiments simulating estuarine mixing of seawater with organic-rich river waters. In addition, melting and formation of sea ice leads to further REE depletion at the surface and strong REE enrichment near the shelf

A molecular catalyst for water oxidation that binds to metal oxide surfaces

PubMed Central

Sheehan, Stafford W.; Thomsen, Julianne M.; Hintermair, Ulrich; Crabtree, Robert H.; Brudvig, Gary W.; Schmuttenmaer, Charles A.

2015-01-01

Molecular catalysts are known for their high activity and tunability, but their solubility and limited stability often restrict their use in practical applications. Here we describe how a molecular iridium catalyst for water oxidation directly and robustly binds to oxide surfaces without the need for any external stimulus or additional linking groups. On conductive electrode surfaces, this heterogenized molecular catalyst oxidizes water with low overpotential, high turnover frequency and minimal degradation. Spectroscopic and electrochemical studies show that it does not decompose into iridium oxide, thus preserving its molecular identity, and that it is capable of sustaining high activity towards water oxidation with stability comparable to state-of-the-art bulk metal oxide catalysts. PMID:25757425

Parametric study of laser photovoltaic energy converters

NASA Technical Reports Server (NTRS)

Walker, G. H.; Heinbockel, J. H.

1987-01-01

Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

Alkali oxide-tantalum, niobium and antimony oxide ionic conductors

NASA Technical Reports Server (NTRS)

Roth, R. S.; Brower, W. S.; Parker, H. S.; Minor, D. B.; Waring, J. L.

1975-01-01

The phase equilibrium relations of four systems were investigated in detail. These consisted of sodium and potassium antimonates with antimony oxide and tantalum and niobium oxide with rubidium oxide as far as the ratio 4Rb2O:llB2O5 (B=Nb, Ta). The ternary system NaSbO3-Sb2O4-NaF was investigated extensively to determine the actual composition of the body centered cubic sodium antimonate. Various other binary and ternary oxide systems involving alkali oxides were examined in lesser detail. The phases synthesized were screened by ion exchange methods to determine mobility of the mobility of the alkali ion within the niobium, tantalum or antimony oxide (fluoride) structural framework. Five structure types warranted further investigation; these structure types are (1) hexagonal tungsten bronze (HTB), (2) pyrochlore, (3) the hybrid HTB-pyrochlore hexagonal ordered phases, (4) body centered cubic antimonates and (5) 2K2O:3Nb2O5. Although all of these phases exhibit good ion exchange properties only the pyrochlore was prepared with Na(+) ions as an equilibrium phase and as a low porosity ceramic. Sb(+3) in the channel interferes with ionic conductivity in this case, although relatively good ionic conductivity was found for the metastable Na(+) ion exchanged analogs of RbTa2O5F and KTaWO6 pyrochlore phases.

Synthesis of graphene oxide through different oxidation degrees for solar cells

NASA Astrophysics Data System (ADS)

Zhang, Xiaoshan; Wang, Huan; Huang, Tianjiao; Wen, Lingling; Zhou, Liya

2018-03-01

Graphene is known as an electro-chemical material and widely used in electro-chemical devices, especially in solar cell. Decreasing the thickness of the layer is a critical way to improve the electrochemical property of solar cells as far as possible. Among the various oxidation approaches, presented herein is a facile approach, which is easier, less cost and more effective, environmental benign with the greener processing and without any requirement for post purification, towards the synthesis of graphene oxide (GO) with different oxidation degrees by potassium ferrate (K2FeO4). A modified method using less amount of oxidizing agent is reported herein. It is the pretreatment of the synthesis of graphite, which maintains the thermal cycle of the system. This novel reports to compound GO with controlled oxidation degrees can not only increase the quantity of oxygen-containing functional groups on GO surface, increase space between graphene oxide layer and facilitate the dispersion of graphene in aqueous solution. Thus, the modified method shows prospect for large-scale production of graphene oxide and its novel application, in addition to its derivative and market potential for solar cells.

Characterization of Graphite Oxide and Reduced Graphene Oxide Obtained from Different Graphite Precursors and Oxidized by Different Methods Using Raman Spectroscopy.

PubMed

Muzyka, Roksana; Drewniak, Sabina; Pustelny, Tadeusz; Chrubasik, Maciej; Gryglewicz, Grażyna

2018-06-21

In this paper, the influences of the graphite precursor and the oxidation method on the resulting reduced graphene oxide (especially its composition and morphology) are shown. Three types of graphite were used to prepare samples for analysis, and each of the precursors was oxidized by two different methods (all samples were reduced by the same method of thermal reduction). Each obtained graphite oxide and reduced graphene oxide was analysed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (RS).

Electrolytic oxidation of anthracite

USGS Publications Warehouse

Senftle, F.E.; Patton, K.M.; Heard, I.

1981-01-01

An anthracite slurry can be oxidized only with difficulty by electrolytic methods in which aqueous electrolytes are used if the slurry is confined to the region of the anode by a porous pot or diaphragm. However, it can be easily oxidized if the anthracite itself is used as the anode. No porous pot or diaphragm is needed. Oxidative consumption of the coal to alkali-soluble compounds is found to proceed preferentially at the edges of the aromatic planes. An oxidation model is proposed in which the chief oxidants are molecular and radical species formed by the electrolytic decomposition of water at the coal surface-electrolyte interface. The oxidation reactions proposed account for the opening of the aromatic rings and the subsequent formation of carboxylic acids. The model also explains the observed anisotropic oxidation and the need for the porous pot or diaphragm used in previous studies of the oxidation of coal slurries. ?? 1981.

Catalytic process for formaldehyde oxidation

NASA Technical Reports Server (NTRS)

Kielin, Erik J. (Inventor); Brown, Kenneth G. (Inventor); D'Ambrosia, Christine M. (Inventor)

1996-01-01

Disclosed is a process for oxidizing formaldehyde to carbon dioxide and water without the addition of energy. A mixture of formaldehyde and an oxidizing agent (e.g., ambient air containing formaldehyde) is exposed to a catalyst which includes a noble metal dispersed on a metal oxide which possesses more than one oxidation state. Especially good results are obtained when the noble metal is platinum, and the metal oxide which possesses more than one oxidation state is tin oxide. A promoter (i.e., a small amount of an oxide of a transition series metal) may be used in association with the tin oxide to provide very beneficial results.

Induction of melasma by 1064-nm Q-switched neodymium:yttrium-aluminum-garnet laser therapy for acquired bilateral nevus of Ota-like macules (Hori nevus): A study on related factors in the Chinese population.

PubMed

Wang, Ben; Xie, Hong-Fu; Tan, Jun; Xie, Hong-Ju; Xu, Lin-Yong; Ding, Rong; Liu, Fang-Fen; Chen, Xiang; Jian, Dan; Li, Ji

2016-06-01

Laser treatment has emerged as a common treatment modality for acquired bilateral nevus of Ota-like macules (ABNOM). To identify the ratio of melasma induction and exacerbation before and after laser therapy for ABNOM and to observe the risk factors related to the induction and exacerbation of melasma by laser therapy, we analyzed related factors of 1268 adult Chinese patients who underwent 1064-nm Q-switched neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (QNYL) treatment using case series and case-control studies. Overall, 24.0% of the ABNOM patients had mixed melasma. Among the ABNOM patients without melasma, after laser therapy the development of melasma was more frequently noted in patients older than 35 years (P < 0.0001), as well in patients whose ABNOM was less than 10 cm(2) (P = 0.027), ABNOM were light (similar to yellow-brown) in color (P = 0.021) and skin types were closer to type IV (P < 0.0001). New melasma lesions also appeared most frequently in the zygomatic region (P < 0.0001). Among the ABNOM patients with melasma, 89.5% experienced worsening of their melasma, irrespective of their related factors above. We concluded that the risk of inducing melasma is great after 1064-nm QNYL treatment in ABNOM patients, and particularly in the patients with both ABNOM and melasma. ABNOM patients should be treated as early as possible and before the age of 35 years. © 2016 Japanese Dermatological Association.

Ethylene Oxide

Cancer.gov

Learn about ethylene oxide, which can raise your risk of lymphoma and leukemia. Exposure may occur through industrial emissions, tobacco smoke, and the use of products sterilized with ethylene oxide, such as certain medical products or cosmetics.

Partial oxidation of methane (POM) assisted solid oxide co-electrolysis

DOEpatents

Chen, Fanglin; Wang, Yao

2017-02-21

Methods for simultaneous syngas generation by opposite sides of a solid oxide co-electrolysis cell are provided. The method can comprise exposing a cathode side of the solid oxide co-electrolysis cell to a cathode-side feed stream; supplying electricity to the solid oxide co-electrolysis cell such that the cathode side produces a product stream comprising hydrogen gas and carbon monoxide gas while supplying oxygen ions to an anode side of the solid oxide co-electrolysis cell; and exposing the anode side of the solid oxide co-electrolysis cell to an anode-side feed stream. The cathode-side feed stream comprises water and carbon dioxide, and the anode-side feed stream comprises methane gas such that the methane gas reacts with the oxygen ions to produce hydrogen and carbon monoxide. The cathode-side feed stream can further comprise nitrogen, hydrogen, or a mixture thereof.

Protective Effect of Adhesive Systems associated with Neodymium-doped Yttrium Aluminum Garnet Laser on Enamel Erosive/Abrasive Wear.

PubMed

Crastechini, Erica; Borges, Alessandra B; Becker, Klaus; Attin, Thomas; Torres, Carlos Rg

2017-10-01

This study evaluated the efficacy of self-etching adhesive systems associated or not associated with the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser on the protection against enamel erosive/abrasive wear. Bovine enamel specimens were demineralized with 0.3% citric acid (5 minutes). The samples were randomly assigned to eight groups (n = 20): SB - Single Bond Universal (3M/ESPE); SB+L - Single Bond Universal + laser (80 mJ/10 Hz); FB - Futurabond U (Voco); FB+L -Futurabond U + laser; GEN - G-aenial bond (GC); GEN+L -G-aenial bond + laser; L - laser irradiation; and C - no treatment. The laser was applied before light curing. The samples were subjected to erosive/abrasive challenges (0.3% citric acid - 2 minutes and tooth brushing four times daily for 5 days). Enamel surface loss was recovered profilometrically by comparison of baseline and final profiles. The adhesive layer thickness, retention percentage of the protective layer, and microhardness of cured adhesive were measured. Data were analyzed using one-way analysis of variance and Tukey's test (5%). There were significant differences for all parameters (p = 0.0001). Mean values ± SD and results of the Tukey's test were: Surface wear: GEN - 4.88 (±1.09)a, L - 5.04 ± 0.99)a, FB - 5.32 (±0.93)ab, GEN + L - 5.46 (±1.27)abc, SB + L - 5.78 (±1.12)abc, FB + L - 6.23 (±1.25)bc, SB - 6.35 (±1.11)c, and C - 6.46 (±0.61)c; layer thickness: GEN - 15.2 (±8.63)c, FB - 5.06 (±1.96)a, GEN + L - 13.96 (±7.07)bc, SB + L - 4.24 (±2.68)a, FB + L - 9.03 (±13.02)abc, and SB - 7.49 (±2.80)ab; retention: GEN - 68.89 (±20.62)c, FB - 54.53 (±24.80)abc, GEN + L - 59.90 (±19.79)abc, SB + L - 63.37 (±19.30)bc, FB + L - 42.23 (±17.68) a, and SB - 47.78 (±18.29)ab; microhardness: GEN - 9.27 (±1.75)c; FB - 6.99 (±0.89)b; GEN + L - 6.22 (±0.87)ab; SB + L - 15.48 (±2.51)d; FB + L - 10.67 (±1.58)c; SB - 5.00 (±1.60)a. The application of Futurabond U and G-aenial bond on enamel surface, as well as the Nd

Anaerobic ammonium oxidation mediated by Mn-oxides: from sediment to strain level.

PubMed

Javanaud, Cedric; Michotey, Valerie; Guasco, Sophie; Garcia, Nicole; Anschutz, Pierre; Canton, Mathieu; Bonin, Patricia

2011-11-01

Nitrite and (29)N(2) productions in slurry incubations of anaerobically sediment after (15)NO(3) or (15)NH(4) labelling in the presence of Mn-oxides suggested that anaerobic Mn-oxides mediated nitrification coupled with denitrification in muddy intertidal sediments of Arcachon Bay (SW Atlantic French coast). From this sediment, bacterial strains were isolated and physiologically characterized in terms of Mn-oxides and nitrate reduction as well as potential anaerobic nitrification. One of the isolated strain, identified as Marinobacter daepoensis strain M4AY14, was a denitrifier. Nitrous oxide production by this strain was demonstrated in the absence of nitrate and with Mn-oxides and NH(4) amendment, giving indirect proof of anaerobic nitrate or nitrite production. Anaerobic Mn-oxide-mediated nitrification was confirmed by (29)N(2) production in the presence of (15)NO(3) and (14)NH(4) under denitrifying conditions. Anaerobic nitrification by M4AY14 seemed to occur only in the absence of nitrate, or at nitrate levels lower than that of Mn-oxides. Most of the other isolates were affiliated with the Shewanella genus and were able to use both nitrate and Mn-oxides as electron acceptors. When both electron acceptors were present, whatever their concentrations, nitrate and Mn-oxide reduction co-occurred. These data indicate that bacterial Mn-oxide reduction could be an important process in marine sediments with low oxygen concentrations, and demonstrate for the first time the role of bacteria in anaerobic Mn-mediated nitrification. Copyright © 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Thermally exfoliated graphite oxide

NASA Technical Reports Server (NTRS)

Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Abdala, Ahmed (Inventor)

2011-01-01

A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

Kinetic and catalytic analysis of mesoporous metal oxides on the oxidation of Rhodamine B

NASA Astrophysics Data System (ADS)

Xaba, Morena S.; Noh, Ji-Hyang; Mokgadi, Keabetswe; Meijboom, Reinout

2018-05-01

In this study, we demonstrate the synthesis and catalytic activity of different mesoporous transition metal oxides, silica (SiO2), copper oxide (CuO), chromium oxide (Cr2O3), iron oxide (Fe2O3) cobalt oxide (Co3O4), cerium oxide (CeO2) and nickel oxide (NiO), on the oxidation of a pollutant dye, Rhodamine B (RhB). These metal oxides were synthesized by inverse micelle formation method and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), adsorption-desorption isotherms (BET) and H2-temperature programmed reduction (TPR). UV-vis spectrophotometry was used to monitor the time-resolved absorbance of RhB at λmax = 554 nm. Mesoporous copper oxide was calcined at different final heating temperatures of 250, 350, 450 and 550 °C, and each mesoporous copper oxide catalyst showed unique physical properties and catalytic behavior. Mesoporous CuO-550 with the smallest characteristic path length δ, proved to be the catalyst of choice for the oxidation of RhB in aqueous media. We observed that the oxidation of RhB in aqueous media is dependent on the crystallite size and characteristic path length of the mesoporous metal oxide. The Langmuir-Hinshelwood model was used to fit the experimental data and to prove that the reaction occurs on the surface of the mesoporous CuO. The thermodynamic parameters, EA, ΔH#, ΔS# and ΔG# were calculated and catalyst recycling and reusability were demonstrated.

An engineered polypeptide around nano-sized manganese-calcium oxide: copying plants for water oxidation.

PubMed

Najafpour, Mohammad Mahdi; Ghobadi, Mohadeseh Zarei; Sarvi, Bahram; Haghighi, Behzad

2015-09-14

Synthesis of new efficient catalysts inspired by Nature is a key goal in the production of clean fuel. Different compounds based on manganese oxide have been investigated in order to find their water-oxidation activity. Herein, we introduce a novel engineered polypeptide containing tyrosine around nano-sized manganese-calcium oxide, which was shown to be a highly active catalyst toward water oxidation at low overpotential (240 mV), with high turnover frequency of 1.5 × 10(-2) s(-1) at pH = 6.3 in the Mn(III)/Mn(IV) oxidation range. The compound is a novel structural and efficient functional model for the water-oxidizing complex in Photosystem II. A new proposed clever strategy used by Nature in water oxidation is also discussed. The new model of the water-oxidizing complex opens a new perspective for synthesis of efficient water-oxidation catalysts.

In vitro analysis of laser meniscectomy.

PubMed

Vangsness, C T; Akl, Y; Nelson, S J; Liaw, L H; Smith, C F; Marshall, G J

1995-01-01

Partial meniscectomies were performed on 32 fresh human meniscal autopsy specimens. The following laser systems were tested: carbon dioxide (CO2), neodymium:yttrium aluminum garnet (Nd:YAG), potassium titanyl phosphate (KTP), holmium:YAG (Ho:YAG), and excimer. Meniscectomies with these lasers were compared with scalpel, mechanical, and electrocautery meniscectomies. Lasers were applied to specimens in and out of normal saline. Routine hematoxylin and eosin and sirius red sections were prepared for each specimen, and the depths of thermal changes were analyzed. Scanning electron microscopy was used to visualize the meniscectomy interface. Among these specimens, the scalpel and mechanical meniscectomies showed the least extension of cellular changes (range, 10-15 nm). The excimer laser caused the least tissue changes of the lasers tested. Tissue changes were less extensive with the pulsed CO2 laser than with the holmium:YAG, neodymium:YAG, and KTP lasers. Scanning electron microscopy showed that use of the scalpel meniscectomy resulted in the smoothest meniscectomy edge, followed by use of the excimer, CO2, holmium:YAG, neodymium:YAG, and KTP lasers. The most surface disruption occurred with electrocautery. Meniscectomies under saline required more energy and took longer in each case, with the holmium:YAG, neodymium:YAG, and CO2 laser cutting the best. Saline meniscectomies showed less thermal change. The CO2 and KTP lasers cut best in air.

Treatment Outcomes of Long-Pulsed Nd: YAG Laser for Two Different Subtypes of Rosacea

PubMed Central

Say, Ekin Mese; Gökdemir, Gonca

2015-01-01

Background: A variety of lasers have been used for the treatment of rosacea. However, treatment of this condition with long-pulsed neodymium-doped yttrium aluminium garnet laser has not been reported yet. Objective: To assess the efficacy and safety of long-pulsed neodymium-doped yttrium aluminium garnet laser in two different subtypes (erythematotelangiectatic and papulopustular) of rosacea. Methods: A total of 66 patients were enrolled in the study. All of the patients were treated with long-pulsed neodymium-doped yttrium aluminium garnet laser with 3- to 4-week intervals. Rosacea severity score was assessed by using photographs. Improvement in severity was defined as the percentage reduction in severity scores from baseline to the end of treatment. Patients were also asked about their own opinions of improvement at the end of the treatment. Side effects were also documented. Results: Good to excellent improvement was achieved in up to 50 percent of the patients in the erythematotelangiectatic and papulopustular groups. Percent improvement of global severity was significantly greater in the erythematotelangiectatic patients than in the papulopustular patients. The majority of patients from both groups noted a significant improvement of the lesions. Hypopigmented atrophic scars were seen in two patients. Conclusion: The long-pulsed neodymium-doped yttrium aluminium garnet laser is a safe and effective treatment for vascular and inflammatory lesions of rosacea. PMID:26430486

Dual-step synthesis of 3-dimensional niobium oxide - Zinc oxide

NASA Astrophysics Data System (ADS)

Rani, Rozina Abdul; Zoolfakar, Ahmad Sabirin; Rusop, M.

2018-05-01

A facile fabrication process for constructing 3-dimensional (3D) structure of Niobium oxide - Zinc oxide (Nb2O5-ZnO) consisting of branched ZnO microrods on top of nanoporous Nb2O5 films was developed based on dual-step synthesis approach. The preliminary procedure was anodization of sputtered niobium metal on Fluorine doped Tin Oxide (FTO) to produce nanoporous Nb2O5, and continued with the growth of branched microrods of ZnO by hydrothermal process. This approach offers insight knowledge on the development of novel 3D metal oxide films via dual-step synthesis process, which might potentially use for multi-functional applications ranging from sensing to photoconversion.

Laccase-Functionalized Graphene Oxide Assemblies as Efficient Nanobiocatalysts for Oxidation Reactions

PubMed Central

Patila, Michaela; Kouloumpis, Antonios; Gournis, Dimitrios; Rudolf, Petra; Stamatis, Haralambos

2016-01-01

Multi-layer graphene oxide-enzyme nanoassemblies were prepared through the multi-point covalent immobilization of laccase from Trametes versicolor (TvL) on functionalized graphene oxide (fGO). The catalytic properties of the fGO-TvL nanoassemblies were found to depend on the number of the graphene oxide-enzyme layers present in the nanostructure. The fGO-TvL nanoassemblies exhibit an enhanced thermal stability at 60 °C, as demonstrated by a 4.7-fold higher activity as compared to the free enzyme. The multi-layer graphene oxide-enzyme nanoassemblies can efficiently catalyze the oxidation of anthracene, as well as the decolorization of an industrial dye, pinacyanol chloride. These materials retained almost completely their decolorization activity after five reaction cycles, proving their potential as efficient nano- biocatalysts for various applications. PMID:26927109

Platinum Electrodeposition at Unsupported Electrochemically Reduced Nanographene Oxide for Enhanced Ammonia Oxidation

PubMed Central

2015-01-01

The electrochemical reduction of highly oxidized unsupported graphene oxide nanosheets and its platinum electrodeposition was done by the rotating disk slurry electrode technique. Avoiding the use of a solid electrode, graphene oxide was electrochemically reduced in a slurry solution with a scalable process without the use of a reducing agent. Graphene oxide nanosheets were synthesized from carbon platelet nanofibers to obtain highly hydrophilic layers of less than 250 nm in width. The graphene oxide and electrochemically reduced graphene oxide/Pt (erGOx/Pt) hybrid materials were characterized through different spectroscopy and microscopy techniques. Pt nanoparticles with 100 facets, clusters, and atoms at erGOx were identified by high resolution transmission electron microscopy (HRTEM). Cyclic voltammetry was used to characterize the electrocatalytic activity of the highly dispersed erGOx/Pt hybrid material toward the oxidation of ammonia, which showed a 5-fold current density increase when compared with commercially available Vulcan/Pt 20%. This is in agreement with having Pt (100) facets present in the HRTEM images of the erGOx/Pt material. PMID:24417177

Mild Oxidation Promotes and Advanced Oxidation Impairs Remodeling of Human High-Density Lipoprotein in vitro

PubMed Central

Gao, Xuan; Jayaraman, Shobini; Gursky, Olga

2008-01-01

SUMMARY High-density lipoproteins (HDL) prevent atherosclerosis by removing cholesterol from macrophages and by exerting anti-oxidant and anti-inflammatory effects. Oxidation is thought to impair HDL functions, yet certain oxidative modifications may be advantageous; thus, mild oxidation reportedly enhances cell cholesterol uptake by HDL whereas extensive oxidation impairs it. To elucidate the underlying energetic and structural basis, we analyzed the effects of copper and hypochlorite (that preferentially oxidize lipids and proteins, respectively) on thermal stability of plasma spherical HDL. Circular dichroism, light scattering, calorimetry, gel electrophoresis and electron microscopy showed that mild oxidation destabilizes HDL and accelerates protein dissociation and lipoprotein fusion, while extensive oxidation inhibits these reactions; this inhibition correlates with massive protein cross-linking and lipolysis. We propose that mild oxidation lowers kinetic barriers for HDL remodeling due to diminished apolipoprotein affinity for lipids resulting from oxidation of methionine and aromatic residues in apolipoproteins A-I and A-II followed by protein cross-linking into dimers and/or trimers. In contrast, advanced oxidation inhibits protein dissociation and HDL fusion due to lipid re-distribution from core to surface upon lipolysis and to massive protein cross-linking. Our results help reconcile the apparent controversy in the studies of oxidized HDL and suggest that mild oxidation may benefit HDL functions. PMID:18190928

High Energy Solid State and Free Electron Laser Systems in Tactical Aviation

DTIC Science & Technology

2005-06-01

specifically neodymium and ytterbium doped yttrium aluminum garnet (Nd:YAG and Yb:YAG) have been shown to produce pump absorption efficiencies (i.e...Search Radar Dish Aluminum Alloy 2.71 10.0 0.91 321 932 300 22.1 SAM nosecone Ceramic* 3.0 1.0 0.9 1600 3300 250 12.1 T-72 Tank Armor Steel...development at Lawrence Livermore National Laboratory, is the solid-state heat capacity laser, which is an array of diode- pumped neodymium-doped gadolinium

Transition metal-catalyzed oxidation of sulfur(IV) oxides. Atmospheric-relevant processes and mechanisms

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

Brandt, C.; Eldik, R. van

1995-01-01

The transition metal-catalyzed oxidation of sulfur(IV) oxides has been known for more than 100 years. There is a significant lack of information on the actual role of the transition metal-catalyzed reactions, and much of the earlier work was performed without a detailed knowledge of the chemical system. For this reason attention is focused on the role of transition metal ions in the oxidation of sulfur(IV) oxides in terms of the coordination chemistry involved, as well as the stability and chemical behavior of the various participating species. The oxidation process of sulfur(IV) oxides plays an important role in atmospheric chemistry (e.g.more » acid rain formation) as well as industrial processes (e.g. desulfurization of plume gases and ore). The present report deals with the mechanism of the transition metal-catalyzed oxidation of sulfur(IV) oxides with the aim to discuss this in terms of atmospheric and chemical processes. In addition, the authors would like to emphasize the key role of oxygen in these processes. 1,076 refs.« less

Synthesis of Graphene Oxide by Oxidation of Graphite with Ferrate(VI) Compounds: Myth or Reality?

PubMed

Sofer, Zdeněk; Luxa, Jan; Jankovský, Ondřej; Sedmidubský, David; Bystroň, Tomáš; Pumera, Martin

2016-09-19

It is well established that graphene oxide can be prepared by the oxidation of graphite using permanganate or chlorate in an acidic environment. Recently, however, the synthesis of graphene oxide using potassium ferrate(VI) ions has been reported. Herein, we critically replicate and evaluate this new ferrate(VI) oxidation method. In addition, we test the use of potassium ferrate(VI) for the synthesis of graphene oxide under various experimental routes. The synthesized materials are analyzed by a number of analytical methods in order to confirm or disprove the possibility of synthesizing graphene oxide by the ferrate(VI) oxidation route. Our results confirm the unsuitability of using ferrate(VI) for the oxidation of graphite on graphene oxide because of its high instability in an acidic environment and low oxidation power in neutral and alkaline environments. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oxidation of Octopus vulgaris hemocyanin by nitrogen oxides

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

Salvato, B.; Giacometti, G.M.; Beltramini, M.

1989-01-24

The reaction of Octopus vulgaris hemocyanin with nitrite was studied under a variety of conditions in which the green half-met derivative is formed. Analytical evidence shows that the amount of chemically detectable nitrite in various samples of the derivative is not proportional to the cupric copper detected by EPR. The kinetics of oxidation of hemocyanin as a function of protein concentration and pH, in the presence of nitrite and ascorbate, is consistent with a scheme in which NO/sub 2/ is the reactive oxidant. We suggest that the green half-methemocyanin contains a metal center with one cuprous and one cupric coppermore » without an exogenous nitrogen oxide ligand.« less

SELECTIVE OXIDATION OF ALCOHOLS OVER VANADIUM PHOSPHORUS OXIDE CATALYST USING HYDROGEN PEROXIDE

EPA Science Inventory

Oxidation of various alcohols is studied in liquid phase under nitrogen atmosphere over vanadium phosphorus oxide catalyst in an environmentally friendly protocol using hydrogen peroxide. The catalyst and the method are found to be suitable for the selective oxidation of a variet...

Oxide surfaces and metal/oxide interfaces studied by grazing incidence X-ray scattering

NASA Astrophysics Data System (ADS)

Renaud, Gilles

Experimental determinations of the atomic structure of insulating oxide surfaces and metal/oxide interfaces are scarce, because surface science techniques are often limited by the insulating character of the substrate. Grazing incidence X-ray scattering (GIXS), which is not subject to charge effects, can provide very precise information on the atomic structure of oxide surfaces: roughness, relaxation and reconstruction. It is also well adapted to analyze the atomic structure, the registry, the misfit relaxation, elastic or plastic, the growth mode and the morphology of metal/oxide interfaces during their growth, performed in situ. GIXS also allows the analysis of thin films and buried interfaces, in a non-destructive way, yielding the epitaxial relationships, and, by variation of the grazing incidence angle, the lattice parameter relaxation along the growth direction. On semi-coherent interfaces, the existence of an ordered network of interfacial misfit dislocations can be demonstrated, its Burger's vector determined, its ordering during in situ annealing cycles followed, and sometimes even its atomic structure can be addressed. Careful analysis during growth allows the modeling of the dislocation nucleation process. This review emphasizes the new information that GIXS can bring to oxide surfaces and metal/oxide interfaces by comparison with other surface science techniques. The principles of X-ray diffraction by surfaces and interfaces are recalled, together with the advantages and properties of grazing angles. The specific experimental requirements are discussed. Recent results are presented on the determination of the atomic structure of relaxed or reconstructed oxide surfaces. A description of results obtained during the in situ growth of metal on oxide surfaces is also given, as well as investigations of thick metal films on oxide surfaces, with lattice parameter misfit relaxed by an array of dislocations. Recent work performed on oxide thin films having

Simultaneous effect of temperature, cyanide and ammonia-oxidizing bacteria concentrations on ammonia oxidation.

PubMed

Do, Hyojin; Lim, Juntaek; Shin, Seung Gu; Wu, Yi-Ju; Ahn, Johng-Hwa; Hwang, Seokhwan

2008-11-01

For biological nitrification, a set of experiments were carried out to approximate the response of lag period along with ammonia oxidation rate with respect to different concentrations of cyanide (CN-) and ammonia-oxidizing bacteria (AOB), and temperature variation in laboratory-scale batch reactors. The effects of simultaneous changes in these three factors on ammonia oxidation were quantitatively estimated and modeled using response surface analysis. The lag period and the ammonia oxidation rate responded differently to changes in the three factors. The lag period and the ammonia oxidation rate were significantly affected by the CN- and AOB concentrations, while temperature changes only affected the ammonia oxidation rate. The increase of AOB concentration and temperature alleviated the inhibition effect of cyanide on ammonia oxidation. The statistical method used in this study can be extended to estimate the quantitative effects of other environmental factors that can change simultaneously.

Actinide oxide photodiode and nuclear battery

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

Sykora, Milan; Usov, Igor

Photodiodes and nuclear batteries may utilize actinide oxides, such a uranium oxide. An actinide oxide photodiode may include a first actinide oxide layer and a second actinide oxide layer deposited on the first actinide oxide layer. The first actinide oxide layer may be n-doped or p-doped. The second actinide oxide layer may be p-doped when the first actinide oxide layer is n-doped, and the second actinide oxide layer may be n-doped when the first actinide oxide layer is p-doped. The first actinide oxide layer and the second actinide oxide layer may form a p/n junction therebetween. Photodiodes including actinide oxidesmore » are better light absorbers, can be used in thinner films, and are more thermally stable than silicon, germanium, and gallium arsenide.« less

In Situ Electrochemical Oxidation Tuning of Transition Metal Disulfides to Oxides for Enhanced Water Oxidation

DOE PAGES

Chen, Wei; Wang, Haotian; Li, Yuzhang; ...

2015-07-15

The development of catalysts with earth-abundant elements for efficient oxygen evolution reactions is of paramount significance for clean and sustainable energy storage and conversion devices. Our group demonstrated recently that the electrochemical tuning of catalysts via lithium insertion and extraction has emerged as a powerful approach to improve catalytic activity. Here we report a novel in situ electrochemical oxidation tuning approach to develop a series of binary, ternary, and quaternary transition metal (e.g., Co, Ni, Fe) oxides from their corresponding sulfides as highly active catalysts for much enhanced water oxidation. The electrochemically tuned cobalt–nickel–iron oxides grown directly on the three-dimensionalmore » carbon fiber electrodes exhibit a low overpotential of 232 mV at current density of 10 mA cm –2, small Tafel slope of 37.6 mV dec –1, and exceptional long-term stability of electrolysis for over 100 h in 1 M KOH alkaline medium, superior to most non-noble oxygen evolution catalysts reported so far. The materials evolution associated with the electrochemical oxidation tuning is systematically investigated by various characterizations, manifesting that the improved activities are attributed to the significant grain size reduction and increase of surface area and electroactive sites. This work provides a promising strategy to develop electrocatalysts for large-scale water-splitting systems and many other applications.« less

Highly Conductive One-Dimensional Manganese Oxide Wires by Coating with Graphene Oxides

NASA Astrophysics Data System (ADS)

Tojo, Tomohiro; Shinohara, Masaki; Fujisawa, Kazunori; Muramatsu, Hiroyuki; Hayashi, Takuya; Ahm Kim, Yoong; Endo, Morinobu

2012-10-01

Through coating with graphene oxides, we have developed a chemical route to the bulk production of long, thin manganese oxide (MnO2) nanowires that have high electrical conductivity. The average diameter of these hybrid nanowires is about 25 nm, and their average length is about 800 nm. The high electrical conductivity of these nanowires (ca. 189.51+/-4.51 µS) is ascribed to the homogeneous coating with conductive graphene oxides as well as the presence of non-bonding manganese atoms. The growth mechanism of the nanowires is theoretically supported by the initiation of morphological conversion from graphene oxide to wrapped structures through the formation of covalent bonds between manganese and oxygen atoms at the graphene oxide edge.

Factors controlling the size of graphene oxide sheets produced via the graphite oxide route.

PubMed

Pan, Shuyang; Aksay, Ilhan A

2011-05-24

We have studied the effect of the oxidation path and the mechanical energy input on the size of graphene oxide sheets derived from graphite oxide. The cross-planar oxidation of graphite from the (0002) plane results in periodic cracking of the uppermost graphene oxide layer, limiting its lateral dimension to less than 30 μm. We use an energy balance between the elastic strain energy associated with the undulation of graphene oxide sheets at the hydroxyl and epoxy sites, the crack formation energy, and the interaction energy between graphene layers to determine the cell size of the cracks. As the effective crack propagation rate in the cross-planar direction is an order of magnitude smaller than the edge-to-center oxidation rate, graphene oxide single sheets larger than those defined by the periodic cracking cell size are produced depending on the aspect ratio of the graphite particles. We also demonstrate that external energy input from hydrodynamic drag created by fluid motion or sonication, further reduces the size of the graphene oxide sheets through tensile stress buildup in the sheets.

Oxidative Stress and Nucleic Acid Oxidation in Patients with Chronic Kidney Disease

PubMed Central

Sung, Chih-Chien; Hsu, Yu-Chuan; Lin, Yuh-Feng

2013-01-01

Patients with chronic kidney disease (CKD) have high cardiovascular mortality and morbidity and a high risk for developing malignancy. Excessive oxidative stress is thought to play a major role in elevating these risks by increasing oxidative nucleic acid damage. Oxidative stress results from an imbalance between reactive oxygen/nitrogen species (RONS) production and antioxidant defense mechanisms and can cause vascular and tissue injuries as well as nucleic acid damage in CKD patients. The increased production of RONS, impaired nonenzymatic or enzymatic antioxidant defense mechanisms, and other risk factors including gene polymorphisms, uremic toxins (indoxyl sulfate), deficiency of arylesterase/paraoxonase, hyperhomocysteinemia, dialysis-associated membrane bioincompatibility, and endotoxin in patients with CKD can inhibit normal cell function by damaging cell lipids, arachidonic acid derivatives, carbohydrates, proteins, amino acids, and nucleic acids. Several clinical biomarkers and techniques have been used to detect the antioxidant status and oxidative stress/oxidative nucleic acid damage associated with long-term complications such as inflammation, atherosclerosis, amyloidosis, and malignancy in CKD patients. Antioxidant therapies have been studied to reduce the oxidative stress and nucleic acid oxidation in patients with CKD, including alpha-tocopherol, N-acetylcysteine, ascorbic acid, glutathione, folic acid, bardoxolone methyl, angiotensin-converting enzyme inhibitor, and providing better dialysis strategies. This paper provides an overview of radical production, antioxidant defence, pathogenesis and biomarkers of oxidative stress in patients with CKD, and possible antioxidant therapies. PMID:24058721

Nitric Oxide as a Mediator of Oxidant Lung Injury Due to Paraquat

NASA Astrophysics Data System (ADS)

Berisha, Hasan I.; Pakbaz, Hedayatollah; Absood, Afaf; Said, Sami I.

1994-08-01

At low concentrations, nitric oxide is a physiological transmitter, but in excessive concentrations it may cause cell and tissue injury. We report that in acute oxidant injury induced by the herbicide paraquat in isolated guinea pig lungs, nitric oxide synthesis was markedly stimulated, as evidenced by increased levels of cyclic GMP in lung perfusate and of nitrite and L-citrulline production in lung tissue. All signs of injury, including increased airway and perfusion pressures, pulmonary edema, and protein leakage into the airspaces, were dose-dependently attenuated or totally prevented by either N^G-nitro-L-arginine methyl ester or N^ω-nitro-L-arginine, selective and competitive inhibitors of nitric oxide synthase. Protection was reversed by excess L-arginine but not by its enantiomer D-arginine. When blood was added to the lung perfusate, the paraquat injury was moderated or delayed as it was when paraquat was given to anesthetized guinea pigs. The rapid onset of injury and its failure to occur in the absence of Ca2+ suggest that constitutive rather than inducible nitric oxide synthase was responsible for the stimulated nitric oxide synthesis. The findings indicate that nitric oxide plays a critical role in the production of lung tissue injury due to paraquat, and it may be a pathogenetic factor in other forms of oxidant tissue injury.

Global patterns of dust and bedrock nutrient supply to montane ecosystems

PubMed Central

Arvin, Lindsay J.; Riebe, Clifford S.; Aciego, Sarah M.; Blakowski, Molly A.

2017-01-01

A global compilation of erosion rates and modeled dust fluxes shows that dust inputs can be a large fraction of total soil inputs, particularly when erosion is slow and soil residence time is therefore long. These observations suggest that dust-derived nutrients can be vital to montane ecosystems, even when nutrient supply from bedrock is substantial. We tested this hypothesis using neodymium isotopes as a tracer of mineral phosphorus contributions to vegetation in the Sierra Nevada, California, where rates of erosion and dust deposition are both intermediate within the global compilation. Neodymium isotopes in pine needles, dust, and bedrock show that dust contributes most of the neodymium in vegetation at the site. Together, the global data sets and isotopic tracers confirm the ecological significance of dust in eroding mountain landscapes. This challenges conventional assumptions about dust-derived nutrients, expanding the plausible range of dust-reliant ecosystems to include many temperate montane regions, despite their relatively high rates of erosion and bedrock nutrient supply. PMID:29226246

Design and Implementation of a Hall Effect Sensor Array Applied to Recycling Hard Drive Magnets

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

Kisner, Roger; Lenarduzzi, Roberto; Killough, Stephen M

Rare earths are an important resource for many electronic components and technologies. Examples abound including Neodymium magnets used in mobile devices and computer hard drives (HDDs), and a variety of renewable energy technologies (e.g., wind turbines). Approximately 21,000 metric tons of Neodymium is processed annually with less than 1% being recycled. An economic system to assist in the recycling of magnet material from post-consumer goods, such as Neodymium Iron Boron magnets commonly found in hard drives is presented. A central component of this recycling measurement system uses an array of 128 Hall Effect sensors arranged in two columns to detectmore » the magnetic flux lines orthogonal to the HDD. Results of using the system to scan planar shaped objects such as hard drives to identify and spatially locate rare-earth magnets for removal and recycling from HDDs are presented. Applications of the sensor array in other identification and localization of magnetic components and assemblies will be presented.« less

Nitric oxide: a physiologic messenger.

PubMed

Lowenstein, C J; Dinerman, J L; Snyder, S H

1994-02-01

To review the physiologic role of nitric oxide, an unusual messenger molecule that mediates blood vessel relaxation, neurotransmission, and pathogen suppression. A MEDLINE search of articles published from 1987 to 1993 that addressed nitric oxide and the enzyme that synthesizes it, nitric oxide synthase. Animal and human studies were selected from 3044 articles to analyze the clinical importance of nitric oxide. Descriptions of the structure and function of nitric oxide synthase were selected to show how nitric oxide acts as a biological messenger molecule. Biochemical and physiologic studies were analyzed if the same results were found by three or more independent observers. Two major classes of nitric oxide synthase enzymes produce nitric oxide. The constitutive isoforms found in endothelial cells and neurons release small amounts of nitric oxide for brief periods to signal adjacent cells, whereas the inducible isoform found in macrophages releases large amounts of nitric oxide continuously to eliminate bacteria and parasites. By diffusing into adjacent cells and binding to enzymes that contain iron, nitric oxide plays many important physiologic roles. It regulates blood pressure, transmits signals between neurons, and suppresses pathogens. Excess amounts, however, can damage host cells, causing neurotoxicity during strokes and causing the hypotension associated with sepsis. Nitric oxide is a simple molecule with many physiologic roles in the cardiovascular, neurologic, and immune systems. Although the general principles of nitric oxide synthesis are known, further research is necessary to determine what role it plays in causing disease.

Improving Thermo-Oxidative Stability of Nitrile Rubber Composites by Functional Graphene Oxide.

PubMed

Zhong, Rui; Zhang, Zhao; Zhao, Hongguo; He, Xianru; Wang, Xin; Zhang, Rui

2018-05-30

Graphene oxide (GO), modified with anti-aging agent p -phenylenediamine (PPD), was added into nitrile rubber (NBR) in order to improve the thermo-oxidative stability of NBR. The modification of GO and the transformation of functional groups were characterized by Fourier transform infrared spectroscopy (FTIR), Raman, and X-ray diffraction (XRD). Mechanical performances of NBR composites before and after the thermo-oxidative aging were recorded. The results of dynamic mechanical analysis (DMA) show an increased storage modulus (G') and a decreased value of area of tan δ peak after introducing modified GO into NBR. It indicates that filler particles show positive interaction with molecular chains. The thermo-oxidative stability of composites was investigated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). Then, the thermo-oxidative aging kinetic parameters were obtained by the Flynn⁻Wall⁻Ozawa (FWO) equation. The results of aging tests show that the thermo-oxidative stability of rubber matrix increases obviously after introducing GO⁻PPD. In addition, mechanical properties (tensile strength and elongation at break) of both before and after aged NBR/GO⁻PPD composites were superior to that of NBR. This work provides meaningful guidance for achieving multifunction thermo-oxidative aging resistance rubber composites.

Oxidant/Antioxidant Balance in Animal Nutrition and Health: The Role of Protein Oxidation

PubMed Central

Celi, Pietro; Gabai, Gianfranco

2015-01-01

This review examines the role that oxidative stress (OS), and protein oxidation in particular, plays in nutrition, metabolism, and health of farm animals. The route by which redox homeostasis is involved in some important physiological functions and the implications of the impairment of oxidative status on animal health and diseases is also examined. Proteins have various and, at the same time, unique biological functions and their oxidation can result in structural changes and various functional modifications. Protein oxidation seems to be involved in pathological conditions, such as respiratory diseases and parasitic infection; however, some studies also suggest that protein oxidation plays a crucial role in the regulation of important physiological functions, such as reproduction, nutrition, metabolism, lactation, gut health, and neonatal physiology. As the characterization of the mechanisms by which OS may influence metabolism and health is attracting considerable scientific interest, the aim of this review is to present veterinary scientists and clinicians with various aspects of oxidative damage to proteins. PMID:26664975

Exceptionally Active and Stable Spinel Nickel Manganese Oxide Electrocatalysts for Urea Oxidation Reaction.

PubMed

Periyasamy, Sivakumar; Subramanian, Palaniappan; Levi, Elena; Aurbach, Doron; Gedanken, Aharon; Schechter, Alex

2016-05-18

Spinel nickel manganese oxides, widely used materials in the lithium ion battery high voltage cathode, were studied in urea oxidation catalysis. NiMn2O4, Ni1.5Mn1.5O4, and MnNi2O4 were synthesized by a simple template-free hydrothermal route followed by a thermal treatment in air at 800 °C. Rietveld analysis performed on nonstoichiometric nickel manganese oxide-Ni1.5Mn1.5O4 revealed the presence of three mixed phases: two spinel phases with different lattice parameters and NiO unlike the other two spinels NiMn2O4 and MnNi2O4. The electroactivity of nickel manganese oxide materials toward the oxidation of urea in alkaline solution is evaluated using cyclic voltammetric measurements. Ni1.5Mn1.5O4 exhibits excellent redox characteristics and lower charge transfer resistances in comparison with other compositions of nickel manganese oxides and nickel oxide prepared under similar conditions.The Ni1.5Mn1.5O4modified electrode oxidizes urea at 0.29 V versus Ag/AgCl with a corresponding current density of 6.9 mA cm(-2). At a low catalyst loading of 50 μg cm(-2), the urea oxidation current density of Ni1.5Mn1.5O4 in alkaline solution is 7 times higher than that of nickel oxide and 4 times higher than that of NiMn2O4 and MnNi2O4, respectively.

PREFACE: Semiconducting oxides Semiconducting oxides

NASA Astrophysics Data System (ADS)

Catlow, Richard; Walsh, Aron

2011-08-01

Semiconducting oxides are amongst the most widely studied and topical materials in contemporary condensed matter science, with interest being driven both by the fundamental challenges posed by their electronic and magnetic structures and properties, and by the wide range of applications, including those in catalysis and electronic devices. This special section aims to highlight recent developments in the physics of these materials, and to show the link between developing fundamental understanding and key application areas of oxide semiconductors. Several aspects of the physics of this wide and expanding range of materials are explored in this special section. Transparent semiconducting oxides have a growing role in several technologies, but challenges remain in understanding their electronic structure and the physics of charge carriers. A related problem concerns the nature of redox processes and the reactions which interconvert defects and charge carriers—a key issue which may limit the extent to which doping strategies may be used to alter electronic properties. The magnetic structures of the materials pose several challenges, while surface structures and properties are vital in controlling catalytic properties, including photochemical processes. The field profits from and exploits a wide range of contemporary physical techniques—both experimental and theoretical. Indeed, the interplay between experiment and computation is a key aspect of contemporary work. A number of articles describe applications of computational methods whose use, especially in modelling properties of defects in these materials, has a long and successful history. Several papers in this special section relate to work presented at a symposium within the European Materials Research Society (EMRS) meeting held in Warsaw in September 2010, and we are grateful to the EMRS for supporting this symposium. We would also like to thank the editorial staff of Journal of Physics: Condensed Matter for

Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction.

PubMed

Kim, Daejin; Powell, Lawrence E; Delmau, Lætitia H; Peterson, Eric S; Herchenroeder, Jim; Bhave, Ramesh R

2015-08-18

The rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acid solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. The resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets.

Facile Access to Graphene Oxide from Ferro-Induced Oxidation

NASA Astrophysics Data System (ADS)

Yu, Chao; Wang, Cai-Feng; Chen, Su

2016-01-01

Methods allowing the oxidation of graphite to graphene oxide (GO) are vital important for the production of graphene from GO. This oxidation reaction has mainly relied on strong acid strategy for 174 years, which circumvents issues associated with toxicity of reagent and product, complex post-treatment, high cost and waste generation. Here, we report a green route for performing this oxidization reaction via a ferro-induced strategy, with use of water, potassium ferrate (Fe(VI)) and hydrogen peroxide (H2O2) as reagents, to produce about 65% yield of GO (vs. 40% for Hummers’ method, the most commonly used concentrated acid strategy) and non-toxic by-products. Moreover, GO produced from this new method shows equivalent performance to those reported previously. This H2SO4-free strategy makes it possible to process graphite into GO in a safe, low-cost, time-saving, energy-efficient and eco-friendly pathway, opening a promising avenue for the large-scale production of GO and GO-based materials.

Facile Access to Graphene Oxide from Ferro-Induced Oxidation.

PubMed

Yu, Chao; Wang, Cai-Feng; Chen, Su

2016-01-28

Methods allowing the oxidation of graphite to graphene oxide (GO) are vital important for the production of graphene from GO. This oxidation reaction has mainly relied on strong acid strategy for 174 years, which circumvents issues associated with toxicity of reagent and product, complex post-treatment, high cost and waste generation. Here, we report a green route for performing this oxidization reaction via a ferro-induced strategy, with use of water, potassium ferrate (Fe(VI)) and hydrogen peroxide (H2O2) as reagents, to produce about 65% yield of GO (vs. 40% for Hummers' method, the most commonly used concentrated acid strategy) and non-toxic by-products. Moreover, GO produced from this new method shows equivalent performance to those reported previously. This H2SO4-free strategy makes it possible to process graphite into GO in a safe, low-cost, time-saving, energy-efficient and eco-friendly pathway, opening a promising avenue for the large-scale production of GO and GO-based materials.

Facile Access to Graphene Oxide from Ferro-Induced Oxidation

PubMed Central

Yu, Chao; Wang, Cai-Feng; Chen, Su

2016-01-01

Methods allowing the oxidation of graphite to graphene oxide (GO) are vital important for the production of graphene from GO. This oxidation reaction has mainly relied on strong acid strategy for 174 years, which circumvents issues associated with toxicity of reagent and product, complex post-treatment, high cost and waste generation. Here, we report a green route for performing this oxidization reaction via a ferro-induced strategy, with use of water, potassium ferrate (Fe(VI)) and hydrogen peroxide (H2O2) as reagents, to produce about 65% yield of GO (vs. 40% for Hummers’ method, the most commonly used concentrated acid strategy) and non-toxic by-products. Moreover, GO produced from this new method shows equivalent performance to those reported previously. This H2SO4-free strategy makes it possible to process graphite into GO in a safe, low-cost, time-saving, energy-efficient and eco-friendly pathway, opening a promising avenue for the large-scale production of GO and GO-based materials. PMID:26818784

Oxidation of Structural Fe(II) in Biotite by Lithotrophic Fe(II)-oxidizing microorganisms

NASA Astrophysics Data System (ADS)

Shelobolina, E.; Blöthe, M.; Xu, H.; Konishi, H.; Roden, E.

2008-12-01

The potential for microbial involvement in the oxidation of Fe(II)-bearing phyllosilicates is an understudied aspect of soil/sediment Fe biogeochemistry. An important property of structural Fe in Fe-bearing smectites is their ability to undergo multiple redox cycles without being mobilized. An obvious choice of mineral substrate for enumeration/isolation of Fe(II)-oxidizing microorganisms would be reduced smectite. But reduced smectite is readily oxidized by air. That is why biotite was chosen as a substrate for this study. In contrast to smectite, biotite is more stable in the presence of air, but incapable of redox cycling. Once Fe(II) is oxidized, biotite is weathered to expendable 2:1 phyllosilicates or kaolinite. First, we evaluated the ability of a neutral-pH lithoautotrophic nitrate-reducing enrichment culture (MPI culture), recovered by Straub et al (Appl. Environ. Microbiol., 1996, 62:1458-1460) from a freshwater ditch, to oxidize two different specimens of biotite. The culture was capable of multiple transfers in anaerobic nitrate-containing biotite suspensions. The growth of MPI culture resulted in decrease of 0.5 N HCl-extractable Fe(II) content and simultaneous nitrate reduction. Cell yields were comparable to those observed for other neutral-pH lithoautotrophic Fe(II)-oxidizing bacteria. High resolution TEM examination revealed structural and chemical changes at the edges of oxidized biotite and formation of reddish amorphous precipitates dominated by Si and Fe. To further evaluate efficiency of biotite for recovery of oxygen- and nitrate-dependent Fe(II) oxidizing cultures microbial enumeration study was performed using subsoil from a site near Madison, WI. The soil is rich in Fe-bearing smectite and shows evidence of redoximorphic features. The enumeration of Fe(II) oxidizing organisms from this sediment showed 10-fold higher efficiency of biotite over soluble Fe(II) for recovery of Fe(II)-oxidizers. Isolation and identification of both aerobic and

Proposed mechanisms for water oxidation by Photosystem II and nanosized manganese oxides.

PubMed

Najafpour, Mohamad Mahdi; Heidari, Sima; Balaghi, S Esmael; Hołyńska, Małgorzata; Sadr, Moayad Hossaini; Soltani, Behzad; Khatamian, Maasoumeh; Larkum, Anthony W; Allakhverdiev, Suleyman I

2017-02-01

Plants, algae and cyanobacteria capture sunlight, extracting electrons from H 2 O to reduce CO 2 into sugars while releasing O 2 in the oxygenic photosynthetic process. Because of the important role of water oxidation in artificial photosynthesis and many solar fuel systems, understanding the structure and function of this unique biological catalyst forms a requisite research field. Herein the structure of the water-oxidizing complex and its ligand environment are described with reference to the 1.9Å resolution X-ray-derived crystallographic model of the water-oxidizing complex from the cyanobacterium Thermosynechococcus vulcanus. Proposed mechanisms for water oxidation by Photosystem II and nanosized manganese oxides are also reviewed and discussed in the paper. Copyright © 2016 Elsevier B.V. All rights reserved.

Uranium oxidation: Characterization of oxides formed by reaction with water by infrared and sorption analyses

NASA Astrophysics Data System (ADS)

Fuller, E. L.; Smyrl, N. R.; Condon, J. B.; Eager, M. H.

1984-04-01

Three different uranium oxide samples have been characterized with respect to the different preparation techniques. The results show that the water reaction with uranium metal occurs cyclically forming laminar layers of oxide which spall off due to the strain at the oxide/metal interface. Single laminae are released if liquid water is present due to the prizing penetration at the reaction zone. The rate of reaction of water with uranium is directly proportional to the amount of adsorbed water on the oxide product. Rapid transport is effected through the open hydrous oxide product. Dehydration of the hydrous oxide irreversibly forms a more inert oxide which cannot be rehydrated to the degree that prevails in the original hydrous product of uranium oxidation with water. Inert gas sorption analyses and diffuse reflectance infrared studies combined with electron microscopy prove valuable in defining the chemistry and morphology of the oxidic products and hydrated intermediates.

Grain boundary oxidation and an analysis of the effects of oxidation on fatigue crack nucleation life

NASA Technical Reports Server (NTRS)

Oshida, Y.; Liu, H. W.

1988-01-01

The effects of preoxidation on subsequent fatigue life were studied. Surface oxidation and grain boundary oxidation of a nickel-base superalloy (TAZ-8A) were studied at 600 to 1000 C for 10 to 1000 hours in air. Surface oxides were identified and the kinetics of surface oxidation was discussed. Grain boundary oxide penetration and morphology were studied. Pancake type grain boundary oxide penetrates deeper and its size is larger, therefore, it is more detrimental to fatigue life than cone-type grain boundary oxide. Oxide penetration depth, a (sub m), is related to oxidation temperature, T, and exposure time, t, by an empirical relation of the Arrhenius type. Effects of T and t on statistical variation of a (sub m) were analyzed according to the Weibull distribution function. Once the oxide is cracked, it serves as a fatigue crack nucleus. Statistical variation of the remaining fatigue life, after the formation of an oxide crack of a critical length, is related directly to the statistical variation of grain boundary oxide penetration depth.

Oxidation mechanism of T91 steel in liquid lead-bismuth eutectic: with consideration of internal oxidation

PubMed Central

Ye, Zhongfei; Wang, Pei; Dong, Hong; Li, Dianzhong; Zhang, Yutuo; Li, Yiyi

2016-01-01

Clarification of the microscopic events that occur during oxidation is of great importance for understanding and consequently controlling the oxidation process. In this study the oxidation product formed on T91 ferritic/martensitic steel in oxygen saturated liquid lead-bismuth eutectic (LBE) at 823 K was characterized at the nanoscale using focused-ion beam and transmission electron microscope. An internal oxidation zone (IOZ) under the duplex oxide scale has been confirmed and characterized systematically. Through the microscopic characterization of the IOZ and the inner oxide layer, the micron-scale and nano-scale diffusion of Cr during the oxidation in LBE has been determined for the first time. The micron-scale diffusion of Cr ensures the continuous advancement of IOZ and inner oxide layer, and nano-scale diffusion of Cr gives rise to the typical appearance of the IOZ. Finally, a refined oxidation mechanism including the internal oxidation and the transformation of IOZ to inner oxide layer is proposed based on the discussion. The proposed oxidation mechanism succeeds in bridging the gap between the existing models and experimental observations. PMID:27734928

Grain boundary oxidation and an analysis of the effects of pre-oxidation on subsequent fatigue life

NASA Technical Reports Server (NTRS)

Oshida, Y.; Liu, H. W.

1986-01-01

The effects of preoxidation on subsequent fatigue life were studied. Surface oxidation and grain boundary oxidation of a nickel-base superalloy (TAZ-8A) were studied at 600 to 1000 C for 10 to 1000 hours in air. Surface oxides were identified and the kinetics of surface oxidation was discussed. Grain boundary oxide penetration and morphology were studied. Pancake type grain boundary oxide penetrates deeper and its size is larger, therefore, it is more detrimental to fatigue life than cone-type grain boundary oxide. Oxide penetration depth, a (sub m), is related to oxidation temperature, T, and exposure time, t, by an empirical relation of the Arrhenius type. Effects of T and t on statistical variation of a (sub m) were analyzed according to the Weibull distribution function. Once the oxide is cracked, it serves as a fatigue crack nucleus. Statistical variation of the remaining fatigue life, after the formation of an oxide crack of a critical length, is related directly to the statistical variation of grain boundary oxide penetration depth.

Evidence for extreme mantle fractionation in early Archaean ultramafic rocks from northern Labrador

NASA Technical Reports Server (NTRS)

Collerson, Kenneth D.; Campbell, Lisa M.; Weaver, Barry L.; Palacz, Zenon A.

1991-01-01

Samarium-neodymium isotope data for tectonically interleaved fragments of lithospheric mantle and meta-komatiite from the North Atlantic craton provide the first direct record of mantle differentiation before 3,800 Myr ago. The results confirm the magnitude of light-rare-earth-element depletion in the early mantle, and also its depleted neodymium isotope composition. The mantle fragments were able to retain these ancient geochemical signatures by virtue of having been tectonically incorporated in buoyant felsic crust, thus escaping recycling and homogenization by mantle convection.

LaF3 core/shell nanoparticles for subcutaneous heating and thermal sensing in the second biological-window

NASA Astrophysics Data System (ADS)

Ximendes, Erving Clayton; Rocha, Uéslen; Kumar, Kagola Upendra; Jacinto, Carlos; Jaque, Daniel

2016-06-01

We report on Ytterbium and Neodymium codoped LaF3 core/shell nanoparticles capable of simultaneous heating and thermal sensing under single beam infrared laser excitation. Efficient light-to-heat conversion is produced at the Neodymium highly doped shell due to non-radiative de-excitations. Thermal sensing is provided by the temperature dependent Nd3+ → Yb3+ energy transfer processes taking place at the core/shell interface. The potential application of these core/shell multifunctional nanoparticles for controlled photothermal subcutaneous treatments is also demonstrated.

Staged membrane oxidation reactor system

DOEpatents

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2014-05-20

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

Staged membrane oxidation reactor system

DOEpatents

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2013-04-16

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

Staged membrane oxidation reactor system

DOEpatents

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2012-09-11

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

METAL OXIDE NANOPARTICLES

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

FERNANDEZ-GARCIA,M.; RODGRIGUEZ, J.A.

2007-10-01

This chapter covers the fundamental science, synthesis, characterization, physicochemical properties and applications of oxide nanomaterials. Explains fundamental aspects that determine the growth and behavior of these systems, briefly examines synthetic procedures using bottom-up and top-down fabrication technologies, discusses the sophisticated experimental techniques and state of the art theory results used to characterize the physico-chemical properties of oxide solids and describe the current knowledge concerning key oxide materials with important technological applications.

The fate of arsenic adsorbed on iron oxides in the presence of arsenite-oxidizing bacteria.

PubMed

Zhang, Zhennan; Yin, Naiyi; Du, Huili; Cai, Xiaolin; Cui, Yanshan

2016-05-01

Arsenic (As) is a redox-active metalloid whose toxicity and mobility in soil depend on its oxidation state. Arsenite [As(III)] can be oxidized by microbes and adsorbed by minerals in the soil. However, the combined effects of these abiotic and biotic processes are not well understood. In this study, the fate of arsenic in the presence of an isolated As(III)-oxidizing bacterium (Pseudomonas sp. HN-1, 10(9) colony-forming units (CFUs)·ml(-1)) and three iron oxides (goethite, hematite, and magnetite at 1.6 g L(-1)) was determined using batch experiments. The total As adsorption by iron oxides was lower with bacteria present and was higher with iron oxides alone. The total As adsorption decreased by 78.6%, 36.0% and 79.7% for goethite, hematite and magnetite, respectively, due to the presence of bacteria. As(III) adsorbed on iron oxides could also be oxidized by Pseudomonas sp. HN-1, but the oxidation rate (1.3 μmol h(-1)) was much slower than the rate in the aqueous phase (96.2 μmol h(-1)). Therefore, the results of other studies with minerals only might overestimate the adsorptive capacity of solids in natural systems; the presence of minerals might hinder As(III) oxidation by microbes. Under aerobic conditions, in the presence of iron oxides and As(III)-oxidizing bacteria, arsenic is adsorbed onto iron oxides within the adsorption capacity, and As(V) is the primary form in the solid and aqueous phases. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nanoscale oxidation and complex oxide growth on single crystal iron surfaces and external electric field effects.

PubMed

Jeon, Byoungseon; Van Overmeere, Quentin; van Duin, Adri C T; Ramanathan, Shriram

2013-02-14

Oxidation of iron surfaces and oxide growth mechanisms have been studied using reactive molecular dynamics. Oxide growth kinetics on Fe(100), (110), and (111) surface orientations has been investigated at various temperatures and/or an external electric field. The oxide growth kinetics decreases in the order of (110), (111), and (100) surfaces at 300 K over 1 ns timescale while higher temperature increases the oxidation rate. The oxidation rate shows a transition after an initial high rate, implying that the oxide formation mechanism evolves, with iron cation re-ordering. In early stages of surface oxide growth, oxygen transport through iron interstitial sites is dominant, yielding non-stoichiometric wüstite characteristics. The dominant oxygen inward transport decreases as the oxide thickens, evolving into more stoichiometric oxide phases such as wüstite or hematite. This also suggests that cation outward transport increases correspondingly. In addition to oxidation kinetics simulations, formed oxide layers have been relaxed in the range of 600-1500 K to investigate diffusion characteristics, fitting these results into an Arrhenius relation. The activation energy of oxygen diffusion in oxide layers formed on Fe(100), (110), and (111) surfaces was estimated to be 0.32, 0.26, and 0.28 eV, respectively. Comparison between our modeling results and literature data is then discussed. An external electric field (10 MV cm(-1)) facilitates initial oxidation kinetics by promoting oxygen transport through iron lattice interstitial sites, but reaches self-limiting thickness, showing that similar oxide formation stages are maintained when cation transport increases. The effect of the external electric field on iron oxide structure, composition, and oxide activation energy is found to be minimal, whereas cation outward migration is slightly promoted.

Photo-electrochemical Oxidation of Organic C1 Molecules over WO3 Films in Aqueous Electrolyte: Competition Between Water Oxidation and C1 Oxidation.

PubMed

Reichert, Robert; Zambrzycki, Christian; Jusys, Zenonas; Behm, R Jürgen

2015-11-01

To better understand organic-molecule-assisted photo-electrochemical water splitting, photo-electrochemistry and on-line mass spectrometry measurements are used to investigate the photo-electrochemical oxidation of the C1 molecules methanol, formaldehyde, and formic acid over WO3 film anodes in aqueous solution and its competition with O2 evolution from water oxidation O2 (+) and CO2 (+) ion currents show that water oxidation is strongly suppressed by the organic species. Photo-electro-oxidation of formic acid is dominated by formation of CO2 , whereas incomplete oxidation of formaldehyde and methanol prevails, with the selectivity for CO2 formation increasing with increasing potential and light intensity. The mechanistic implications for the photo-electro-oxidation of the organic molecules and its competition with water oxidation, which could be derived from this novel approach, are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oxidation-resistant cermet

NASA Technical Reports Server (NTRS)

Phillips, W. M.

1977-01-01

Chromium metal alloys and chromium oxide ceramic are combined to produce cermets with oxidation-resistant properties. Application of cermets includes use in hot corrosive environments requiring strong resistive materials.

A Study of Oxides for Solid Oxide Cells

NASA Astrophysics Data System (ADS)

Comets, Olivier

As the world energy consumption increases, it is a question of global health to increase energy production efficiency and to reduce CO2 emissions. In that respect, solid oxide cells are solid state devices that convert directly fuel into electricity, or vice versa. In fact, when run in fuel cell mode, such devices produce electricity with efficiency up to twice that of current natural gas power plants. However, systems equipped with them have only seen limited commercialization owing to issues of cost, durability, and performance. In this thesis, three different aspects of solid oxide cells are studied. First, the effects of stress on the properties of mixed ionic electronic conducting oxides are considered. Such oxides can be used as electrode materials, where they are often subject to large stresses, which can, in turn, affect their performance. Hence, understanding the relationship between stress and properties in such materials is crucial. Non-stoichiometry in strontium substituted lanthanum cobaltite is found to increase under tension and to decrease under compression. Then, degradation taking place when the cell is run in electrolysis mode is discussed. A high current allows for a high production rate of hydrogen gas. However, this can also lead to oxygen bubble nucleating in the electrolyte and subsequent degradation of the cell. The analysis conducted here shows that such nucleation phenomenon can be avoided by keeping the overpotential at the oxygen electrode below a critical value. Finally, the growth and coarsening of catalyst nanoparticles at the surface of an oxide is studied. Scientists have developed new oxides for anodes in which a catalyst material is dissolved and exsolves under operating conditions. As the performance of the cell is controlled by the surface area of the catalyst phase, understanding the kinetics of the growth is critical to predict the performance of the cell. An approach is developed to study the growth of one particle, in the

OXIDATION-REDUCTION POTENTIAL MEASUREMENTS OF IMPORTANT OXIDANTS IN DRINKING WATER

EPA Science Inventory

Oxidation-reduction (redox) reactions are important in drinking water treatment and distribution. Oxidation-reduction potential (ORP) measurements of water reflect the tendency of major constituents in the water to accept or lose electrons. Although ORP measurements are valuable...

Design for Oxidation Resistance

NASA Technical Reports Server (NTRS)

Smialek, James L.; Schaeffer, Jon C.; Barrett, Charles A.

1997-01-01

Alloys intended for use in high-temperature environment rely on the formation of a continuous, compact, slow-growing oxide layer for oxidation and hot corrosion resistance. To be protective, this oxide layer must be chemically, thermodynamically stable. Successful alloy design for oxidative environment is best achieved by developing alloys that are capable of forming adherent scales of either alumina (Al2O3), chromia (Cr2O3), or silica (SiO2). In this article, emphasis has been placed on the issue related to high-temperature oxidation of superalloys used in gas turbine engine application. Despite the complexity of these alloys, optimal performance has been associated with protective alumina scale formation. As will be described below, both compositional makeup and protective coatings play key role in providing oxidation protection. Other high-temperature materials described include nickel and titanium aluminide intermetallics, refractory metal, and ceramics.

Microbial Hydrocarbon Co-oxidation

PubMed Central

Raymond, R. L.; Jamison, V. W.; Hudson, J. O.

1967-01-01

Nocardia cultures, isolated from soil by use of n-paraffins as the sole carbon source, have been shown to bring about significant oxidation of several methyl-substituted mono- and dicyclic aromatic hydrocarbons. Oxygen uptake by washed cell suspensions was not a reliable indicator of oxidation. Under co-oxidation conditions in shaken flasks, o- and p-xylenes were oxidized to their respective mono-aromatic acids, o-toluic and p-toluic acids. In addition, a new fermentation product, 2, 3-dihydroxy-p-toluic acid, was found in the p-xylene oxidation system. Of 10 methyl-substituted naphthalenes tested (1-methyl, 2-methyl, 1, 3-dimethyl, 1, 4-dimethyl, 1, 5-dimethyl, 1, 8-dimethyl, 1, 6-dimethyl, 2, 3-dimethyl, 2, 6-dimethyl, 2, 7-dimethyl), only those containing a methyl group in the β position were oxidized at this position to the mono acid. PMID:6049305

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

NASA Astrophysics Data System (ADS)

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

2007-05-01

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

A model for Cryogenian iron formation

NASA Astrophysics Data System (ADS)

Cox, Grant M.; Halverson, Galen P.; Poirier, André; Le Heron, Daniel; Strauss, Justin V.; Stevenson, Ross

2016-01-01

The Neoproterozoic Tatonduk (Alaska) and Holowilena (South Australia) iron formations share many characteristics including their broadly coeval (Sturtian) ages, intimate association with glaciogenic sediments, and mineralogy. We show that these shared characteristics extend to their neodymium (εNd) and iron isotope (δ56Fe) systematics. In both regions δ56Fe values display a distinct up-section trend to isotopically heavier values, while εNd values are primitive and similar to non-ferruginous mudstones within these successions. The δ56Fe profiles are consistent with oxidation of ferruginous waters during marine transgression, and the εNd values imply that much of this iron was sourced from the leaching of continental margin sediments largely derived from continental flood basalts. Rare earth element data indicate a secondary hydrothermal source for this iron.

Wet-cupping removes oxidants and decreases oxidative stress.

PubMed

Tagil, Suleyman Murat; Celik, Huseyin Tugrul; Ciftci, Sefa; Kazanci, Fatmanur Hacievliyagil; Arslan, Muzeyyen; Erdamar, Nazan; Kesik, Yunus; Erdamar, Husamettin; Dane, Senol

2014-12-01

Wet-cupping therapy is one of the oldest known medical techniques. Although it is widely used in various conditions such as acute\\chronic inflammation, infectious diseases, and immune system disorders, its mechanism of action is not fully known. In this study, we investigated the oxidative status as the first step to elucidate possible mechanisms of action of wet cupping. Wet cupping therapy is implemented to 31 healthy volunteers. Venous blood samples and Wet cupping blood samples were taken concurrently. Serum nitricoxide, malondialdehyde levels and activity of superoxide dismutase and myeloperoxidase were measured spectrophotometrically. Wet cupping blood had higher activity of myeloperoxidase, lower activity of superoxide dismutase, higher levels of malondialdehyde and nitricoxide compared to the venous blood. Wet cupping removes oxidants and decreases oxidative stress. Copyright © 2014 Elsevier Ltd. All rights reserved.

Low temperature processed complementary metal oxide semiconductor (CMOS) device by oxidation effect from capping layer.

PubMed

Wang, Zhenwei; Al-Jawhari, Hala A; Nayak, Pradipta K; Caraveo-Frescas, J A; Wei, Nini; Hedhili, M N; Alshareef, H N

2015-04-20

In this report, both p- and n-type tin oxide thin-film transistors (TFTs) were simultaneously achieved using single-step deposition of the tin oxide channel layer. The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase. The oxidation process can be realized by annealing at temperature as low as 190 °C in air, which is significantly lower than the temperature generally required to form tin dioxide. Based on this approach, CMOS inverters based entirely on tin oxide TFTs were fabricated. Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field.

FT-IR Spectroscopic Evidence Of Phase Transition For NaA-ROH-Kerosine-H2O Microemulsion System Containing Nd3+ Ions

NASA Astrophysics Data System (ADS)

Liao, Hua; Xu, Zhen-Hua; Shi, Nai; Wu, Jin-Guang; Xu, Guang-Xian

1989-12-01

In the previous investigation, the saponification of naphthenic acid extractant system has been proved to be a process of the formation of a microemulsion of 14/0 type, and its full extraction of rare earths is a process of destruction of the W/O microemulsion[1]. When NdCl3 is partially extracted with NaA (sodium naphthenate) secoctylalcohol-- kerosine-- water microemulsion system (ME), both the NdA3 and the NaA co-exist in the same organic phase. However,the formation mechanism of microemulsion containing neodymium has not been much studied. In this paper, 10 aliquots of fully saponificated extractants were equilibrated with various amounts of NdC13 solutions respectively, then ten organic phases with different extraction efficiencies of neodymium from 094 to 9094 were obtained. After extraction,the volume of neodymium containing organic phase increased by 5 to 4594, because of the transfer of water molecules. The appearance of these organic phase still remained clear and transparent. The average hydrodynamic radius of the drops were found to be 100-300 Angstrom by using light scattering techniques. The results give a direct evidence of the microemulsion formation in the organic phase. Their FT-IR spectra were measured with CaFa liquid cells utilizing a Nicolet 7199B FT-IR spectrometer. The presence of various amounts of water in the organic phases was clearly detected from the relative intensity changes of 1644 cm-I, which is assigned to the bending mode of 1110 molecules. Fig.1 shows the change of water contents to the percent extraction of neodymium. Comparsion with the FT-IR spectra, it is seen that the 1560 cm-1 peak of the full saponificated extractant is attributed to the asym. stretching vibration of COO''' group, it shifted to 1536 for 100% extration of Nd ions, indicating the formation of neodymium naphthenate (NdA ) from ionic sodium naphthenate. The sym. strethching vibration of COO''' located at 1406 cm-1, it shifted to 1408 cm in 45% Nd extration

Mediated electrochemical oxidation (MEO) process: a study on nonylphenol ethoxylates (NPE) oxidation in batch mode using cerium (IV) oxidant

NASA Astrophysics Data System (ADS)

Setiyanto, H.; Adyatmika, I. M.; Syaifullah, M. M.; Zulfikar, M. A.; Buchari

2018-05-01

Nonylphenol ethoxylate (NPE-10) is one type of non-ionic surfactants from the class of alkylphenol ethoxylate (APE). This compound is already tightened their use in European Union countries. However, these surfactants are still used widely in Indonesia because the price is relatively cheap. Consequently, these compounds can accumulate in aquatic environments. NPE-10 can disrupt aquatic ecosystems. This study aimed to describe the electro-oxidation process of NPE-10 based on the parameters of a potential difference, concentration of NPE-10, concentration of Ce (III), and oxidation time. The result of oxidation NPE-10 was measured by the amount of current generated from voltammetry technique. Studies of cyclic voltammetry using carbon paste electrodes illustrates the potential value of the oxidation of Ce (III) / Ce (IV) of 1.25 V and the reduction potential value of Ce (IV) / Ce (III) of 1.192 V. NPE-10 are electroactive irreversible because it only provides the potential value of oxidation at 1.44 V. Percent of total degradation of 84.96% was obtained at electro-oxidation of 500 ppm NPE-10 by the addition of 0.015 M Ce (III) for 90 minutes at 0.2 M H2SO4and the use of potential of 6 V.

Equilibrating metal-oxide cluster ensembles for oxidation reactions using oxygen in water

Treesearch

Ira A. Weinstock; Elena M. G. Barbuzzi; Michael W. Wemple; Jennifer J. Cowan; Richard S. Reiner; Dan M. Sonnen; Robert A. Heintz; James S. Bond; Craig L. Hill

2001-01-01

Although many enzymes can readily and selectively use oxygen in water--the most familiar and attractive of all oxidants and solvents, respectively–-the design of synthetic catalysts for selective water-based oxidation processes utilizing molecular oxygen remains a daunting task. Particularly problematic is the fact that oxidation of substrates by O2 involves radical...

RELATIONSHIPS BETWEEN OXIDATION-REDUCTION, OXIDANT, AND PH IN DRINKING WATER

EPA Science Inventory

Oxidation and reduction (redox) reactions are very important in drinking water. Oxidation-reduction potential (ORP) measurements reflect the redox state of water. Redox measurements are not widely made by drinking water utilities in part because they are not well understood. The ...

Fatty acid oxidation promotes reprogramming by enhancing oxidative phosphorylation and inhibiting protein kinase C.

PubMed

Lin, Zhaoyu; Liu, Fei; Shi, Peiliang; Song, Anying; Huang, Zan; Zou, Dayuan; Chen, Qin; Li, Jianxin; Gao, Xiang

2018-02-26

Changes in metabolic pathway preferences are key events in the reprogramming process of somatic cells to induced pluripotent stem cells (iPSCs). The optimization of metabolic conditions can enhance reprogramming; however, the detailed underlying mechanisms are largely unclear. By comparing the gene expression profiles of somatic cells, intermediate-phase cells, and iPSCs, we found that carnitine palmitoyltransferase (Cpt)1b, a rate-limiting enzyme in fatty acid oxidation, was significantly upregulated in the early stage of the reprogramming process. Mouse embryonic fibroblasts isolated from transgenic mice carrying doxycycline (Dox)-inducible Yamanaka factor constructs were used for reprogramming. Various fatty acid oxidation-related metabolites were added during the reprogramming process. Colony counting and fluorescence-activated cell sorting (FACS) were used to calculate reprogramming efficiency. Fatty acid oxidation-related metabolites were measured by liquid chromatography-mass spectrometry. Seahorse was used to measure the level of oxidative phosphorylation. We found that overexpression of cpt1b enhanced reprogramming efficiency. Furthermore, palmitoylcarnitine or acetyl-CoA, the primary and final products of Cpt1-mediated fatty acid oxidation, also promoted reprogramming. In the early reprogramming process, fatty acid oxidation upregulated oxidative phosphorylation and downregulated protein kinase C activity. Inhibition of protein kinase C also promoted reprogramming. We demonstrated that fatty acid oxidation promotes reprogramming by enhancing oxidative phosphorylation and inhibiting protein kinase C activity in the early stage of the reprogramming process. This study reveals that fatty acid oxidation is crucial for the reprogramming efficiency.

Neodymium, strontium and chromium isotopic studies of the LEW86010 and Angra dos Reis meteorites and the chronology of the angrite parent body

NASA Technical Reports Server (NTRS)

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

1994-01-01

Neodymium, stontium, and chromium isotopic studies of the LEW86010 angrite established its absolute age and the formation interval between its crystallization and condensation of Allende CAIs from the solar nebula. Pyroxene and phosphate were found to contain approximately 8% of its Sm and Nd inventory. A conventional Sm-147-Nd-143 isochron yielded an age of 4.53 +/- 0.04 Ga (2 sigma and Epsilon(sub Nd sup 143)) = 0.45 +/- 1.1. An Sm-146-Nd-142 isochron gives initial Sm-146/Sm-144 = 0.0076 +/- 0.0009 and Epsilon (sub Nd sup 142) = -2.5 +/- 0.4. The Rb-Sr analyses give initial Sr-87/Sr-86 Iota(sub Sr sup 87) = 0.698972 +/- 8 and 0.698970 +/- 18 for LEW and ADOR, respectively, relative to Sr-87/Sr-86 = 0.71025 for NBS987. The difference, Delta Iota(sub Sr Sup 87), between Iota (sub sr sup 87) for the angrites and literature values for Allende CAIs, corresponds to approximately Ma of growth in a solar nebula with a CI chondrite value of Rb-87/Sr-86 = 0.91, or approximately 5 Ma in a nebula with solar photospheric Rb-87/Sr-86 = 1.51. Excess Cr-53 from extinct Mn-53(t(sub 1/2) = 3.7 Ma)in LEW86010 corresponds to initial Mn-53/Mn-55 = 4.4 +/- 1.0 x 10(exp -5) for the inclusions as previously reported by the Paris group (Birck and Allegre, 1988). The Sm-146/Sm-144 value found for LEW86010 corresponds to solar system initial (Sm-146/Sm-144) = 0.0080 +/- 0.0009 for crystallization 8 Ma after Allende, the difference between Pb-Pb ages of angrites and Allende, or 0.0086 +/- 0.0009 for crystallation 18 Ma after Allende, using the Mn-Cr formation interval. The isotopic data are discussed in the context of a model in which an undifferentiated 'chondritic' parent body formed from the solar nebula approximately Ma after Allende CAIs and subsequently underwent differentiation accompanied by loss of volatiles. Parent bodies with Rb/Sr similar to that of CI, CM, or CO chondrites could satisfy the Cr and Sr isotopic systematics. If the angrite parent body had Rb/Sr similar to that of

In situ arsenic oxidation and sorption by a Fe-Mn binary oxide waste in soil.

PubMed

McCann, Clare M; Peacock, Caroline L; Hudson-Edwards, Karen A; Shrimpton, Thomas; Gray, Neil D; Johnson, Karen L

2018-01-15

The ability of a Fe-Mn binary oxide waste to adsorb arsenic (As) in a historically contaminated soil was investigated. Initial laboratory sorption experiments indicated that arsenite [As(III)] was oxidized to arsenate [As(V)] by the Mn oxide component, with concurrent As(V) sorption to the Fe oxide. The binary oxide waste had As(III) and As(V) adsorption capacities of 70mgg -1 and 32mgg -1 respectively. X-ray Absorption Near-Edge Structure and Extended X-ray Absorption Fine Structure at the As K-edge confirmed that all binary oxide waste surface complexes were As(V) sorbed by mononuclear bidentate corner-sharing, with 2 Fe at ∼3.27Ǻ. The ability of the waste to perform this coupled oxidation-sorption reaction in real soils was investigated with a 10% by weight addition of the waste to an industrially As contaminated soil. Electron probe microanalysis showed As accumulation onto the Fe oxide component of the binary oxide waste, which had no As innately. The bioaccessibility of As was also significantly reduced by 7.80% (p<0.01) with binary oxide waste addition. The results indicate that Fe-Mn binary oxide wastes could provide a potential in situ remediation strategy for As and Pb immobilization in contaminated soils. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Modeling Thin Film Oxide Growth

NASA Astrophysics Data System (ADS)

Sherman, Quentin

Thin film oxidation is investigated using two modeling techniques in the interest of better understanding the roles of space charge and non-equilibrium effects. An electrochemical phase-field model of an oxide-metal interface is formulated in one dimension and studied at equilibrium and during growth. An analogous sharp interface model is developed to validate the phase-field model in the thick film limit. Electrochemical profiles across the oxide are shown to deviate from the sharp interface prediction when the oxide film is thin compared to the Debye length, however no effect on the oxidation kinetics is found. This is attributed to the simple thermodynamic and kinetic models used therein. The phase-field model provides a framework onto to which additional physics can be added to better model thin film oxidation. A model for solute trapping during the oxidation of binary alloys is developed to study non-equilibrium effects during the early stages of oxide growth. The model is applied to NiCr alloys, and steady-state interfacial composition maps are presented for the growth of an oxide with the rock salt structure. No detailed experimental data is available to verify the predictions of the solute trapping model, however it is shown to be consistent with the trends observed during the early stages of NiCr oxidation. Lastly, experimental studies of the wet infiltration technique for decorating solid oxide fuel cell anodes with nickel nanoparticles are presented. The effect of nickel nitrate calcination parameters on the resulting nickel oxide microstructures are studied on both porous and planar substrates. Decreasing the calcination temperature and dwell time, as well as a dehydration step after nickel nitrate infiltration, are all shown to decrease the initial nickel oxide particle size, but other factors such as geometry and nickel loading per unit area also affected the final nickel particle size and morphology upon reduction.

Method of producing homogeneous mixed metal oxides and metal-metal oxide mixtures

DOEpatents

Quinby, Thomas C.

1978-01-01

Metal powders, metal oxide powders, and mixtures thereof of controlled particle size are provided by reacting an aqueous solution containing dissolved metal values with excess urea. Upon heating, urea reacts with water from the solution leaving a molten urea solution containing the metal values. The molten urea solution is heated to above about 180.degree. C. whereupon metal values precipitate homogeneously as a powder. The powder is reduced to metal or calcined to form oxide particles. One or more metal oxides in a mixture can be selectively reduced to produce metal particles or a mixture of metal and metal oxide particles.

Graphene-supported metal oxide monolith

DOEpatents

Worsley, Marcus A.; Baumann, Theodore F.; Biener, Juergen; Biener, Monika A.; Wang, Yinmin; Ye, Jianchao; Tylski, Elijah

2017-01-10

A composition comprising at least one graphene-supported metal oxide monolith, said monolith comprising a three-dimensional structure of graphene sheets crosslinked by covalent carbon bonds, wherein the graphene sheets are coated by at least one metal oxide such as iron oxide or titanium oxide. Also provided is an electrode comprising the aforementioned graphene-supported metal oxide monolith, wherein the electrode can be substantially free of any carbon-black and substantially free of any binder.

Mechanical properties of graphene oxides.

PubMed

Liu, Lizhao; Zhang, Junfeng; Zhao, Jijun; Liu, Feng

2012-09-28

The mechanical properties, including the Young's modulus and intrinsic strength, of graphene oxides are investigated by first-principles computations. Structural models of both ordered and amorphous graphene oxides are considered and compared. For the ordered graphene oxides, the Young's modulus is found to vary from 380 to 470 GPa as the coverage of oxygen groups changes, respectively. The corresponding variations in the Young's modulus of the amorphous graphene oxides with comparable coverage are smaller at 290-430 GPa. Similarly, the ordered graphene oxides also possess higher intrinsic strength compared with the amorphous ones. As coverage increases, both the Young's modulus and intrinsic strength decrease monotonically due to the breaking of the sp(2) carbon network and lowering of the energetic stability for the ordered and amorphous graphene oxides. In addition, the band gap of the graphene oxide becomes narrower under uniaxial tensile strain, providing an efficient way to tune the electronic properties of graphene oxide-based materials.

Zinc oxide varistors and/or resistors

DOEpatents

Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

1993-01-01

Varistors and/or resistors that includes doped zinc oxide gel microspheres. The doped zinc oxide gel microspheres preferably have from about 60 to about 95% by weight zinc oxide and from about 5 to about 40% by weight dopants based on the weight of the zinc oxide. The dopants are a plurality of dopants selected from silver salts, boron oxide, silicon oxide and hydrons oxides of aluminum, bismuth, cobalt, chromium, manganese, nickel, and antimony.

Supported versus colloidal zinc oxide for advanced oxidation processes

NASA Astrophysics Data System (ADS)

Laxman, Karthik; Al Rashdi, Manal; Al Sabahi, Jamal; Al Abri, Mohammed; Dutta, Joydeep

2017-07-01

Photocatalysis is a green technology which typically utilizes either supported or colloidal catalysts for the mineralization of aqueous organic contaminants. Catalyst surface area and surface energy are the primary factors determining its efficiency, but correlation between the two is still unclear. This work explores their relation and hierarchy in a photocatalytic process involving both supported and colloidal catalysts. In order to do this the active surface areas of supported zinc oxide nanorods (ZnO NR's) and colloidal zinc oxide nanoparticles (having different surface energies) were equalized and their phenol oxidation mechanism and capacity was analyzed. It was observed that while surface energy had subtle effects on the oxidation rate of the catalysts, the degradation efficiency was primarily a function of the surface area; which makes it a better parameter for comparison when studying different catalyst forms of the same material. Thus we build a case for the use of supported catalysts, wherein their catalytic efficiency was tested to be unaltered over several days under both natural and artificial light, suggesting their viability for practical applications.

Oxidative stress inhibition and oxidant activity by fibrous clays.

PubMed

Cervini-Silva, Javiera; Nieto-Camacho, Antonio; Gómez-Vidales, Virginia

2015-09-01

Fibrous clays (sepiolite, palygorskite) are produced at 1.2m tonnes per year and have a wide range of industrial applications needing to replace long-fibre length asbestos. However, information on the beneficial effects of fibrous clays on health remains scarce. This paper reports on the effect of sepiolite (Vallecas, Spain) and palygorskite (Torrejón El Rubio, Spain) on cell damage via oxidative stress (determined as the progress of lipid peroxidation, LP). The extent of LP was assessed using the Thiobarbituric Acid Reactive Substances assay. The oxidant activity by fibrous clays was quantified using Electron-Paramagnetic Resonance. Sepiolite and palygorskite inhibited LP, whereby corresponding IC50 values were 6557±1024 and 4250±289μgmL(-1). As evidenced by dose-response experiments LP inhibition by palygorskite was surface-controlled. Fibrous clay surfaces did not stabilize HO species, except for suspensions containing 5000μgmL(-1). A strong oxidant (or weak anti-oxidant) activity favours the inhibition of LP by fibrous clays. Copyright © 2015 Elsevier B.V. All rights reserved.

Low Temperature Processed Complementary Metal Oxide Semiconductor (CMOS) Device by Oxidation Effect from Capping Layer

PubMed Central

Wang, Zhenwei; Al-Jawhari, Hala A.; Nayak, Pradipta K.; Caraveo-Frescas, J. A.; Wei, Nini; Hedhili, M. N.; Alshareef, H. N.

2015-01-01

In this report, both p- and n-type tin oxide thin-film transistors (TFTs) were simultaneously achieved using single-step deposition of the tin oxide channel layer. The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase. The oxidation process can be realized by annealing at temperature as low as 190°C in air, which is significantly lower than the temperature generally required to form tin dioxide. Based on this approach, CMOS inverters based entirely on tin oxide TFTs were fabricated. Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field. PMID:25892711

Nitric oxide ameliorates the damaging effects of oxidative stress induced by iron deficiency in cyanobacterium Anabaena 7120.

PubMed

Kaushik, Manish Singh; Srivastava, Meenakshi; Srivastava, Alka; Singh, Anumeha; Mishra, Arun Kumar

2016-11-01

In cyanobacterium Anabaena 7120, iron deficiency leads to oxidative stress with unavoidable consequences. Nitric oxide reduces pigment damage and supported the growth of Anabaena 7120 in iron-deficient conditions. Elevation in nitric oxide accumulation and reduced superoxide radical production justified the role of nitric oxide in alleviating oxidative stress in iron deficiency. Increased activities of antioxidative enzymes and higher levels of ROS scavengers (ascorbate, glutathione and thiol) in iron deficiency were also observed in the presence of nitric oxide. Nitric oxide also supported the membrane integrity of Anabaena cells and reduces protein and DNA damage caused by oxidative stress induced by iron deficiency. Results suggested that nitric oxide alleviates the damaging effects of oxidative stress induced by iron deficiency in cyanobacterium Anabaena 7120.

HYDROCARBON OXIDATION OVER VANADIUM PHOSPHORUS OXIDE CATALYST USING HYDROGEN PEROXIDE

EPA Science Inventory

Selective oxidation of hydrocarbons is one of the very important and challenging areas in industrial chemistry due to the wide ranging utility of the resulting oxygenates in fine chemical synthesis. Most of the existing processes for their oxidations employ toxic and often stoich...

Effect of magnesium oxide content on oxidation behavior of some superalloy-base cermets

NASA Technical Reports Server (NTRS)

Zaplatynsky, I.

1975-01-01

The effect of increasing magnesium oxide (MgO) content on the cyclic oxidation resistance of hot-pressed cermets of MgO in NiCrAlY, MgO in Hoskins-875, MgO in Inconel-702, and MgO in Hastelloy-X was investigated. The cermets with magnesium oxide levels of 5, 10, 20, and 40 vol percent were examined. The cyclic oxidation behavior of these cermets at 1100 and 1200 C in still air was determined by a thermogravimetric method supplemented by X-ray diffraction analysis and light and electron microscopy. In all instances, MgO prevented grain growth in the metallic phase. No evidence of oxidation along interphase boundaries was detected. Cermets of MgO in NiCrAlY and MgO in Hoskins-875 were superior to cermets of MgO in Inconel-702 and MgO in Hastelloy-X. Their oxidation resistance was degraded only when the MgO content was 40 vol percent. The oxidation behavior of MgO-in-Inconel-702 powder cermets containing 5- and 10-vol percent MgO was approximately similar to that of pure Inconel-702 compacts. The 20- and 40-vol percent MgO content reduced the oxidation resistance of MgO-in-Inconel-702 powder cermets relative to that of pure Inconel-702.

A novel hydrogen oxidizer amidst the sulfur-oxidizing Thiomicrospira lineage

PubMed Central

Hansen, Moritz; Perner, Mirjam

2015-01-01

Thiomicrospira species are ubiquitously found in various marine environments and appear particularly common in hydrothermal vent systems. Members of this lineage are commonly classified as sulfur-oxidizing chemolithoautotrophs. Although sequencing of Thiomicrospira crunogena's genome has revealed genes that encode enzymes for hydrogen uptake activity and for hydrogenase maturation and assembly, hydrogen uptake ability has so far not been reported for any Thiomicrospira species. We isolated a Thiomicrospira species (SP-41) from a deep sea hydrothermal vent and demonstrated that it can oxidize hydrogen. We show in vivo hydrogen consumption, hydrogen uptake activity in partially purified protein extracts and transcript abundance of hydrogenases during different growth stages. The ability of this strain to oxidize hydrogen opens up new perspectives with respect to the physiology of Thiomicrospira species that have been detected in hydrothermal vents and that have so far been exclusively associated with sulfur oxidation. PMID:25226028

Influence of oxidation temperature on the oxide scale formation of NiCoCrAl coatings

NASA Astrophysics Data System (ADS)

Sugiarti, E.; Zaini, K. A.; Sundawa, R.; Wang, Y.; Ohnuki, S.; Hayashi, S.

2017-04-01

Intermetalic coatings of NiCoCrAl have been successfully developed on low carbon steel substrate to improve oxidation resistance in extreme environments. The influence of oxidation temperature on the oxide scale formation was studied in the temperature range of 600-1000 °C. The measurements were made in air under isothermal oxidation test for 100 h. The surface morphology showed that a cauliflower like structure developed entire the oxide scale of sample oxidized at 800 °C and 1000 °C, while partly distributed on the surface of sample oxidized at 600 °C. The XRD analysis identified Cr2O3 phase predominantly formed on the oxidized sample at 600 °C and meta-stable Al2O3 with several polymorphs crystalline structures: η, δ, θ, κ, and α-Al2O3 at relatively high temperatures, i.e. 800 °C and 1000 °C. A Cross-sectional microstructure showed that complex and porous structures formed on the top surface of 600 °C and 1000 °C samples. In contrast, a very thin oxide scale formed on 800 °C oxidized samples and it appeared to act as a diffusion barrier of oxygen to diffuse inward, hence could increase in the service life of carbon steel substrate.

Oxidation of anthracene using waste Mn oxide minerals: the importance of wetting and drying sequences.

PubMed

Clarke, Catherine; Tourney, Janette; Johnson, Karen

2012-02-29

PAHs are a common problem in contaminated urban soils due to their recalcitrance. This study presents results on the oxidation of anthracene on synthetic and natural Mn oxide surfaces. Evaporation of anthracene spiked Mn oxide slurries in air results in the oxidation of 30% of the anthracene to anthraquinone. Control minerals, quartz and calcite, also oxidised a small but significant proportion of the anthracene (4.5% and 14% conversion, respectively) when spiked mineral slurries were evaporated in air. However, only Mn oxide minerals showed significant anthracene oxidation (5-10%) when evaporation took place in the absence of oxygen (N2 atmosphere). In the fully hydrated systems where no drying took place, natural Mn oxides showed an increase in anthracene oxidation with decreasing pH, with a conversion of 75% anthracene at pH 4. These results show both acidification and drying favor the oxidation of anthracene on Mn oxide mineral surfaces. It has also been demonstrated that non-redox active mineral surfaces, such as calcite, may play a role in contaminant breakdown during wetting and drying sequences. Given that climate changes suggest that wetting and drying sequences are likely to become more significant these results have important implications for contaminated land remediation technologies. Copyright © 2012 Elsevier B.V. All rights reserved.

Zinc oxide overdose

MedlinePlus

Zinc oxide is an ingredient in many products. Some of these are certain creams and ointments used ... prevent or treat minor skin burns and irritation. Zinc oxide overdose occurs when someone eats one of ...

Zinc oxide varistors and/or resistors

DOEpatents

Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

1993-07-27

Varistors and/or resistors are described that include doped zinc oxide gel microspheres. The doped zinc oxide gel microspheres preferably have from about 60 to about 95% by weight zinc oxide and from about 5 to about 40% by weight dopants based on the weight of the zinc oxide. The dopants are a plurality of dopants selected from silver salts, boron oxide, silicon oxide and hydrons oxides of aluminum, bismuth, cobalt, chromium, manganese, nickel, and antimony.

Synergistic effect of graphene oxide on the methanol oxidation for fuel cell application

NASA Astrophysics Data System (ADS)

Siwal, Samarjeet; Ghosh, Sarit; Nandi, Debkumar; Devi, Nishu; Perla, Venkata K.; Barik, Rasmita; Mallick, Kaushik

2017-09-01

Aromatic polypyrene was synthesized by the oxidative polymerization of pyrene with potassium tetrachloropalladate (II), as oxidant. During the polymerization process the palladium salt was reduced to metallic palladium and forms the metal-polymer composite material. Polypyrene stabilized palladium nanoparticles showed electrocatalytic activity toward the oxidation of methanol. The performance of the electrocatalytic activity was substantially improved with the incorporation of graphene oxide to the palladium-polypyrene composite and the synergistic performance was attributed to the electronic and structural properties of the system.

Carbon monoxide oxidation over three different states of copper: Development of a model metal oxide catalyst

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

Jernigan, Glenn Geoffrey

1994-10-01

Carbon monoxide oxidation was performed over the three different oxidation states of copper -- metallic (Cu), copper (I) oxide (Cu 2O), and copper (II) oxide (CuO) as a test case for developing a model metal oxide catalyst amenable to study by the methods of modern surface science and catalysis. Copper was deposited and oxidized on oxidized supports of aluminum, silicon, molybdenum, tantalum, stainless steel, and iron as well as on graphite. The catalytic activity was found to decrease with increasing oxidation state (Cu > Cu 2O > CuO) and the activation energy increased with increasing oxidation state (Cu, 9 kcal/molmore » < Cu 2O, 14 kcal/mol < CuO, 17 kcal/mol). Reaction mechanisms were determined for the different oxidation states. Lastly, NO reduction by CO was studied. A Cu and CuO catalyst were exposed to an equal mixture of CO and NO at 300--350 C to observe the production of N 2 and CO 2. At the end of each reaction, the catalyst was found to be Cu 2O. There is a need to study the kinetics of this reaction over the different oxidation states of copper.« less

Iron oxides stimulate sulfate-driven anaerobic methane oxidation in seeps

DOE PAGES

Sivan, Orit; Antler, Gilad; Turchyn, Alexandra V.; ...

2014-09-22

Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with 13C-labeled methane showed co-occurring sulfate reduction, AOM, and methanogenesis. The isotope fractionation factors for sulfur and oxygen isotopes in sulfate were about 40‰ and 22‰, respectively, reinforcing the difference between microbial sulfate reduction in methane seeps versus other sedimentary environments (for example, sulfur isotope fractionation above 60‰ in sulfate reduction coupled to organicmore » carbon oxidation or in diffusive sedimentary sulfate–methane transition zone). The addition of hematite to these microcosm experiments resulted in significant microbial iron reduction as well as enhancing sulfate-driven AOM. The magnitude of the isotope fractionation of sulfur and oxygen isotopes in sulfate from these incubations was lowered by about 50%, indicating the involvement of iron oxides during sulfate reduction in methane seeps. The similar relative change between the oxygen versus sulfur isotopes of sulfate in all experiments (with and without hematite addition) suggests that oxidized forms of iron, naturally present in the sediment incubations, were involved in sulfate reduction, with hematite addition increasing the sulfate recycling or the activity of sulfur-cycling microorganisms by about 40%. Furthermore, these results highlight a role for natural iron oxides during bacterial sulfate reduction in methane seeps not only as nutrient but also as stimulator of sulfur recycling.« less

W-containing oxide layers obtained on aluminum and titanium by PEO as catalysts in thiophene oxidation

NASA Astrophysics Data System (ADS)

Rudnev, V. S.; Lukiyanchuk, I. V.; Vasilyeva, M. S.; Morozova, V. P.; Zelikman, V. M.; Tarkhanova, I. G.

2017-11-01

W-containing oxide layers fabricated on titanium and aluminum alloys by Plasma electrolytic oxidation (PEO) have been tested in the reaction of the peroxide oxidation of thiophene. Samples with two types of coatings have been investigated. Coatings I contained tungsten oxide in the matrix and on the surface of amorphous silica-titania or silica-alumina layers, while coatings II comprised crystalline WO3 and/or Al2(WO4)3. Aluminum-supported catalyst containing a smallest amount of transition metals in the form of tungsten oxides and manganese oxides in low oxidation levels showed high activity and stability.

Metal/oxide interfacial effects on the selective oxidation of primary alcohols

PubMed Central

Zhao, Guofeng; Yang, Fan; Chen, Zongjia; Liu, Qingfei; Ji, Yongjun; Zhang, Yi; Niu, Zhiqiang; Mao, Junjie; Bao, Xinhe; Hu, Peijun; Li, Yadong

2017-01-01

A main obstacle in the rational development of heterogeneous catalysts is the difficulty in identifying active sites. Here we show metal/oxide interfacial sites are highly active for the oxidation of benzyl alcohol and other industrially important primary alcohols on a range of metals and oxides combinations. Scanning tunnelling microscopy together with density functional theory calculations on FeO/Pt(111) reveals that benzyl alcohol enriches preferentially at the oxygen-terminated FeO/Pt(111) interface and undergoes readily O–H and C–H dissociations with the aid of interfacial oxygen, which is also validated in the model study of Cu2O/Ag(111). We demonstrate that the interfacial effects are independent of metal or oxide sizes and the way by which the interfaces were constructed. It inspires us to inversely support nano-oxides on micro-metals to make the structure more stable against sintering while the number of active sites is not sacrificed. The catalyst lifetime, by taking the inverse design, is thereby significantly prolonged. PMID:28098146

An experimental technique to repair cracked teeth using calcium phosphate, melted by a laser beam: an in vitro evaluation.

PubMed

Levy, G C; Koubi, G F

1993-11-01

Using a neodymium: yttrium-aluminum-garnet laser beam to seal vertical root fracture lines with tricalcium phosphate paste represents an alternative treatment for cracked teeth with noted clinical results. This article describes a study of the permeability of molten crystals of hydroxyapatite in the dentin of a cracked root after crack lines have been filled with a preparation of tricalcium phosphate melted by a neodymium: yttrium-aluminum-garnet laser beam. The morphology of the sealed cracks was analyzed under a scanning electron microscope that showed a deep fusion of tricalcium phosphate along crack lines.

Optical characterization of Nd (3+):AgBr.

PubMed

Bunimovich, D; Nagli, L; Katzir, A

1997-10-20

The luminescence of silver bromide crystals, doped with neodymium, was investigated over the visible and near-infrared spectral ranges. The emission, excitation, and absorption spectra were measured over a broad temperature range. The absolute luminescence quantum yield was estimated by comparing the luminescence with that of a neodymium-doped phosphate glass, for which the manufacturer gives a value of 0.4. The Judd-Ofelt analysis was applied to both materials, and transition rates, branching ratios, and quantum efficiencies were calculated for all the observed bands. Good agreement was obtained between theory and experiment.

Application of spark plasma sintering for fabricating Nd-Fe-B composite

NASA Astrophysics Data System (ADS)

Sivkov, A. A.; Ivashutenko, A. S.; Lomakina, A. A.

2015-10-01

Constant magnets are applied in such fields as electric equipment and electric generators with fixed rotor. Rare earth metal neodymium is well known as promising material. Production of magnets by sintering three elements (neodymium, iron and boron) is one the most promising methods. But there are difficulties in choosing the right temperature for sintering and further processing. Structure and properties of the product, consisted of rare earth metals, was analyzed. X-ray analysis of the resulting product and the finished constant magnet was performed. Vickers microhardness was obtained.

The influence of oxidation time on the properties of oxidized zinc films

NASA Astrophysics Data System (ADS)

Rambu, A. P.

2012-09-01

The effect of oxidation time on the structural characteristics and electronic transport mechanism of zinc oxide thin films prepared by thermal oxidation, have been investigated. Zinc metallic films were deposited by thermal evaporation under vacuum, the subsequent oxidation of Zn films being carried out in open atmosphere. XRD and AFM analysis indicate that obtained films posses a polycrystalline structure, the crystallites having a preferential orientation. Structural analysis reveals that microstructure of the films (crystallite size, surface roughness, internal stress) is depending on the oxidation time of metallic films. The electrical behavior of ZnO films was investigated, during a heat treatment (two heating/cooling cycles). It was observed that after the first heating, the temperature dependences of electrical conductivity become reversible. Mott variable range hopping model was proposed to analyze the temperature dependence of the electrical conductivity, in low temperature ranges. Values of some characteristic parameters were calculated.

Oxide film on metal substrate reduced to form metal-oxide-metal layer structure

NASA Technical Reports Server (NTRS)

Youngdahl, C. A.

1967-01-01

Electrically conductive layer of zirconium on a zirconium-oxide film residing on a zirconium substrate is formed by reducing the oxide in a sodium-calcium solution. The reduced metal remains on the oxide surface as an adherent layer and seems to form a barrier that inhibits further reaction.

Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation.

PubMed

Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H; Navrotsky, Alexandra

2013-05-28

Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn(3+)/Mn(4+) ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states.

Characterization of oxide nanoparticles in Al-free and Al-containing oxide dispersion strengthened ferritic steels.

PubMed

Lee, Jae Hoon; Kim, Jeoung Han

2013-09-01

Oxide nanoparticles in oxide dispersion strengthened (ODS) ferritic steels with and without Al have been characterized by transmission electron microscopy. It is confirmed that most of the complex oxide particles consist of Y2TiO5 for 18Cr-ODS steel and YAlO3 or YAl5O12 for 18Cr5Al-ODS steel, respectivley. The addition of 5% Al in 18Cr-ODS steel leads to the formation of larger oxide particles and the reduction in their number density. For 18Cr-ODS steel, 87% of the oxide particles are coherent. The misfit strain of the coherent particles and a few semi-coherent particles is about 0.034 and 0.056, respectively. For 18Cr5Al-ODS steel, 75% of the oxide particles are semi-coherent, of which the misfit strain is 0.091 and 0.125, respectively. These results suggest that for the Al-containing ODS steel the Al addition accelerates the formation of semi-coherent oxide particles and its larger coherent and semi-coherent particles result in the larger misfit strain between the oxide particle and alloy matrix, indicating that the coherence of oxide nanoparticles in ODS steels is size-dependent.

Is Oxidized Thioredoxin a Major Trigger for Cysteine Oxidation? Clues from a Redox Proteomics Approach

PubMed Central

García-Santamarina, Sarela; Boronat, Susanna; Calvo, Isabel A.; Rodríguez-Gabriel, Miguel; Ayté, José; Molina, Henrik

2013-01-01

Abstract Cysteine oxidation mediates oxidative stress toxicity and signaling. It has been long proposed that the thioredoxin (Trx) system, which consists of Trx and thioredoxin reductase (Trr), is not only involved in recycling classical Trx substrates, such as ribonucleotide reductase, but it also regulates general cytoplasmic thiol homeostasis. To investigate such a role, we have performed a proteome-wide analysis of cells expressing or not the two components of the Trx system. We have compared the reversibly oxidized thiol proteomes of wild-type Schizosaccharomyces pombe cells with mutants lacking Trx or Trr. Specific Trx substrates are reversibly-oxidized in both strain backgrounds; however, in the absence of Trr, Trx can weakly recycle its substrates at the expense of an alternative electron donor. A massive thiol oxidation occurs only in cells lacking Trr, with 30% of all cysteine-containing peptides being reversibly oxidized; this oxidized cysteine proteome depends on the presence of Trxs. Our observations lead to the hypothesis that, in the absence of its reductase, the natural electron donor Trx becomes a powerful oxidant and triggers general thiol oxidation. Antioxid. Redox Signal. 18, 1549–1556. PMID:23121505

Nitrate-Dependent Ferrous Iron Oxidation by Anaerobic Ammonium Oxidation (Anammox) Bacteria

PubMed Central

Oshiki, M.; Ishii, S.; Yoshida, K.; Fujii, N.; Ishiguro, M.; Satoh, H.

2013-01-01

We examined nitrate-dependent Fe2+ oxidation mediated by anaerobic ammonium oxidation (anammox) bacteria. Enrichment cultures of “Candidatus Brocadia sinica” anaerobically oxidized Fe2+ and reduced NO3− to nitrogen gas at rates of 3.7 ± 0.2 and 1.3 ± 0.1 (mean ± standard deviation [SD]) nmol mg protein−1 min−1, respectively (37°C and pH 7.3). This nitrate reduction rate is an order of magnitude lower than the anammox activity of “Ca. Brocadia sinica” (10 to 75 nmol NH4+ mg protein−1 min−1). A 15N tracer experiment demonstrated that coupling of nitrate-dependent Fe2+ oxidation and the anammox reaction was responsible for producing nitrogen gas from NO3− by “Ca. Brocadia sinica.” The activities of nitrate-dependent Fe2+ oxidation were dependent on temperature and pH, and the highest activities were seen at temperatures of 30 to 45°C and pHs ranging from 5.9 to 9.8. The mean half-saturation constant for NO3− ± SD of “Ca. Brocadia sinica” was determined to be 51 ± 21 μM. Nitrate-dependent Fe2+ oxidation was further demonstrated by another anammox bacterium, “Candidatus Scalindua sp.,” whose rates of Fe2+ oxidation and NO3− reduction were 4.7 ± 0.59 and 1.45 ± 0.05 nmol mg protein−1 min−1, respectively (20°C and pH 7.3). Co-occurrence of nitrate-dependent Fe2+ oxidation and the anammox reaction decreased the molar ratios of consumed NO2− to consumed NH4+ (ΔNO2−/ΔNH4+) and produced NO3− to consumed NH4+ (ΔNO3−/ΔNH4+). These reactions are preferable to the application of anammox processes for wastewater treatment. PMID:23624480

CATALYTIC OXIDATION OF ALCOHOLS AND EPOXIDATION OF OLEFINS WITH HYDROGEN PEROXIDE AS OXIDANT

EPA Science Inventory

Hydrogen peroxide (H2O2) is an ideal oxidant of choice for these oxidations due to economic and environmental reasons by giving water as a by-product. Two catalysts used are vanadium phosphorus oxide (VPO) and Fe3+/montmorillonite-K10 catalyst prepared by ion-exchange method at a...

Oxidative desulfurization of benzene fraction on transition metal oxides

NASA Astrophysics Data System (ADS)

Boikov, E. B.; Vishnetskaya, M. V.

2013-02-01

It is established that molecular oxygen is able to oxidize thiophene selectively in a mixture with benzene on V2O5 · MoO3. The introduction of thiophene inhibits the oxidation of benzene. It is shown that the conversion of thiophene during operation of the catalyst is reduced at first and then increases until it reaches its initial value.

Genetic resistance to malaria, oxidative stress and hemoglobin oxidation.

PubMed

Destro Bisol, G

1999-09-01

I describe a model which posits the molecular basis of some malaria-resistance genes in the interaction between oxidized hemoglobin and membrane components. The model is supported by a considerable body of evidence which indicates that erythrocytes of genetically protected individuals (carriers of sickle cell trait, alpha- and beta-thalassemia, and G6PD deficiency) are susceptible to the increase of oxidation of hemoglobin following H2O2 release in the host cell by Plasmodium falciparum. I suggest that the irreversible interaction between oxidized hemoglobin and the red cell membrane could trigger mechanisms that: (i) reduce invasion of erythrocytes by the falciparum parasite; (ii) impair parasite survival and development within the cell; (iii) accelerate infected erythrocyte clearance by phagocytosis.

Does oxidative stress shorten telomeres?

PubMed

Boonekamp, Jelle J; Bauch, Christina; Mulder, Ellis; Verhulst, Simon

2017-05-01

Oxidative stress shortens telomeres in cell culture, but whether oxidative stress explains variation in telomere shortening in vivo at physiological oxidative stress levels is not well known. We therefore tested for correlations between six oxidative stress markers and telomere attrition in nestling birds (jackdaws Corvus monedula ) that show a high rate of telomere attrition in early life. Telomere attrition was measured between ages 5 and 30 days, and was highly variable (average telomere loss: 323 bp, CV = 45%). Oxidative stress markers were measured in blood at age 20 days and included markers of oxidative damage (TBARS, dROMs and GSSG) and markers of antioxidant protection (GSH, redox state, uric acid). Variation in telomere attrition was not significantly related to these oxidative stress markers (| r | ≤ 0.08, n = 87). This finding raises the question whether oxidative stress accelerates telomere attrition in vivo The accumulation of telomere attrition over time depends both on the number of cell divisions and on the number of base pairs lost per DNA replication and, based on our findings, we suggest that in a growing animal cell proliferation, dynamics may be more important for explaining variation in telomere attrition than oxidative stress. © 2017 The Author(s).

Oxidative stress in Alzheimer disease

PubMed Central

Durany, Nuria

2009-01-01

Alzheimer disease (AD) is a progressive dementia affecting a large proportion of the aging population. The histopathological changes in AD include neuronal cell death, formation of amyloid plaques and neurofibrillary tangles. There is also evidence that brain tissue in patients with AD is exposed to oxidative stress (e.g., protein oxidation, lipid oxidation, DNA oxidation and glycoxidation) during the course of the disease. Advanced glycation endproducts (AGEs) are present in amyloid plaques in AD, and its extracellular accumulation may be caused by an accelerated oxidation of glycated proteins. AGEs participate in neuronal death causing direct (chemical) and indirect (cellular) free radical production and consequently increase oxidative stress. The development of drugs for the treatment of AD that breaks the vicious cycles of oxidative stress and neurodegeneration offer new opportunities. These approaches include AGE-inhibitors, antioxidants and anti-inflammatory substances, which prevent free radical production. PMID:19372765

Oxidative stress in Alzheimer disease.

PubMed

Gella, Alejandro; Durany, Nuria

2009-01-01

Alzheimer disease (AD) is a progressive dementia affecting a large proportion of the aging population. The histopathological changes in AD include neuronal cell death, formation of amyloid plaques and neurofibrillary tangles. There is also evidence that brain tissue in patients with AD is exposed to oxidative stress (e.g., protein oxidation, lipid oxidation, DNA oxidation and glycoxidation) during the course of the disease. Advanced glycation endproducts (AGEs) are present in amyloid plaques in AD, and its extracellular accumulation may be caused by an accelerated oxidation of glycated proteins. AGEs participate in neuronal death causing direct (chemical) and indirect (cellular) free radical production and consequently increase oxidative stress. The development of drugs for the treatment of AD that breaks the vicious cycles of oxidative stress and neurodegeneration offer new opportunities. These approaches include AGE-inhibitors, antioxidants and anti-inflammatory substances, which prevent free radical production.

The oxidative hypothesis of senescence.

PubMed

Gilca, M; Stoian, I; Atanasiu, V; Virgolici, B

2007-01-01

The oxidative hypothesis of senescence, since its origin in 1956, has garnered significant evidence and growing support among scientists for the notion that free radicals play an important role in ageing, either as "damaging" molecules or as signaling molecules. Age-increasing oxidative injuries induced by free radicals, higher susceptibility to oxidative stress in short-lived organisms, genetic manipulations that alter both oxidative resistance and longevity and the anti-ageing effect of caloric restriction and intermittent fasting are a few examples of accepted scientific facts that support the oxidative theory of senescence. Though not completely understood due to the complex "network" of redox regulatory systems, the implication of oxidative stress in the ageing process is now well documented. Moreover, it is compatible with other current ageing theories (e.g, those implicating the mitochondrial damage/mitochondrial-lysosomal axis, stress-induced premature senescence, biological "garbage" accumulation, etc). This review is intended to summarize and critically discuss the redox mechanisms involved during the ageing process: sources of oxidant agents in ageing (mitochondrial -electron transport chain, nitric oxide synthase reaction- and non-mitochondrial- Fenton reaction, microsomal cytochrome P450 enzymes, peroxisomal beta -oxidation and respiratory burst of phagocytic cells), antioxidant changes in ageing (enzymatic- superoxide dismutase, glutathione-reductase, glutathion peroxidase, catalase- and non-enzymatic glutathione, ascorbate, urate, bilirubine, melatonin, tocopherols, carotenoids, ubiquinol), alteration of oxidative damage repairing mechanisms and the role of free radicals as signaling molecules in ageing.

Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation

PubMed Central

Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H.; Navrotsky, Alexandra

2013-01-01

Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn3+/Mn4+ ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states. PMID:23667149

High temperature oxidation resistant cermet compositions

NASA Technical Reports Server (NTRS)

Phillips, W. M. (Inventor)

1976-01-01

Cermet compositions are designed to provide high temperature resistant refractory coatings on stainless steel or molybdenum substrates. A ceramic mixture of chromium oxide and aluminum oxide form a coating of chromium oxide as an oxidation barrier around the metal particles, to provide oxidation resistance for the metal particles.

Destruction of VX by aqueous-phase oxidation using peroxydisulfate (direct chemical oxidation)

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

Cooper, J.F.; Krueger, R.; Farmer, J.C.

1995-10-11

Chemical warfare agents may be completely destroyed (converted to H{sub 2}O, CO{sub 2}, salts) by oxidation at 90--100 C using acidified ammonium peroxydisulfate, with recycle of NH{sub 4}SO{sub 4} byproduct. The process requires no toxic or expended catalysts and produces no secondary wastes other than the precipitated inorganic content of the agents. To determine oxidative capability of peroxydisulfate at low reductant contents, we measured rate data for oxidation of 20 diverse compounds with diverse functional groups; 4 of these have bonds similar to those found in VX, HD, and GB. On an equivalence basis, integral first-order rate constants for 100more » C oxidation are 0.012{plus_minus}0.005 min{sup {minus}1} for di-isopropyl-methyl-phosphonate, methyl phosphonic acid, triethylamine, and 2,2{prime}-thiodiethanol at low initial concentrations of 50 ppM(as carbon) and pH 1.5. To provide scale-up equations for a bulk chemical agent destruction process, we measured time-dependent oxidation of bulk model chemicals at high concentrations (0.5 N) and developed and tested a quantitative model. A practical process for bulk VX destruction would begin with chemical detoxification by existing techniques (eg, hydrolysis or mild oxidation using oxone), followed by mineralization of the largely detoxified products by peroxydisulfate. Secondary wastes would be avoided by use of commercial electrolysis equipment to regenerate the oxidant. Reagent requirements, mass balance and scaleup parameters are given for VX destruction, using peroxydisulfate alone, or supplemented with hydrogen peroxide. For the use of 2.5 N peroxydisulfate as the oxidant, a 1 m{sup 3} digester will process about 200 kg (as C) per day. The process may be extended to total destruction of HD and hydrolysis products of G agents.« less

Rheological characterization of thermal, thermo-oxidative and photo-oxidative degradation of LDPE

NASA Astrophysics Data System (ADS)

Rolón-Garrido, Víctor Hugo; Wagner, Manfred Hermann

2015-04-01

Rheology has been used to study thermal degradation (V. H. Rolón-Garrido et al., Rheol. Acta 50, 519-535, 2011), thermo-oxidative degradation (V. H. Rolón-Garrido et al., Rheol. Acta 50, 519-535, 2011; V. H. Rolón-Garrido et al., J. Rheol. 57, 105-129, 2013) and photo-oxidative degradation (V. H. Rolón-Garrido and M. H. Wagner, Polym. Degrad. Stab. 99, 136-145, 2014; V. H. Rolón-Garrido and M. H. Wagner, J. Rheol. 58, 199-22 2, 2014; V. H. Rolón-Garrido et al., Polym. Degrad. Stab. 111, 46-54, 2015) of low-density polyethylene (LDPE). This contribution presents the analogies and differences between these types of degradations of LDPE on the linear (by use of van-Gurp Palmen plots) and non-linear viscoelastic properties (by use of the parameters of the MSF model, fmax2 and β), as well as on the failure mode of the samples (through the maximum strain and stress achieved experimentally). In contrast to thermal and thermo-oxidative degradation, the linear viscoelastic properties of photo-oxidated samples were more affected by degradation. In the non-linear regime, for thermal and thermo-oxidative treated samples, the elongational measurements elucidated the role of chain scission and long-chain branching (LCB) formation, while for photo-oxidated LDPE even the competition between chain scission, LCB formation, and gel formation was demonstrated. The failure behavior was found to be determined by a constant maximum strain in thermo-oxidative degradation, if the LDPE has high content in branching points, or in photo-oxidative degraded LDPE, if a considerable portion of gel structure is present. Otherwise, either the maximum strain or stress measured was found to be strain-rate dependent.

The Moraxella catarrhalis nitric oxide reductase is essential for nitric oxide detoxification.

PubMed

Wang, Wei; Kinkel, Traci; Martens-Habbena, Willm; Stahl, David A; Fang, Ferric C; Hansen, Eric J

2011-06-01

Moraxella catarrhalis is a Gram-negative obligate aerobe that is an important cause of human respiratory tract infections. The M. catarrhalis genome encodes a predicted truncated denitrification pathway that reduces nitrate to nitrous oxide. We have previously shown that expression of both the M. catarrhalis aniA (encoding a nitrite reductase) and norB (encoding a putative nitric oxide reductase) genes is repressed by the transcriptional regulator NsrR under aerobic conditions and that M. catarrhalis O35E nsrR mutants are unable to grow in the presence of low concentrations of nitrite (W. Wang, et al., J. Bacteriol. 190:7762-7772, 2008). In this study, we constructed an M. catarrhalis norB mutant and showed that planktonic growth of this mutant is inhibited by low levels of nitrite, whether or not an nsrR mutation is present. To determine the importance of NorB in this truncated denitrification pathway, we analyzed the metabolism of nitrogen oxides by norB, aniA norB, and nsrR norB mutants. We found that norB mutants are unable to reduce nitric oxide and produce little or no nitrous oxide from nitrite. Furthermore, nitric oxide produced from nitrite by the AniA protein is bactericidal for a Moraxella catarrhalis O35E norB mutant but not for wild-type O35E bacteria under aerobic growth conditions in vitro, suggesting that nitric oxide catabolism in M. catarrhalis is accomplished primarily by the norB gene product. Measurement of bacterial protein S-nitrosylation directly implicates nitrosative stress resulting from AniA-dependent nitric oxide formation as a cause of the growth inhibition of norB and nsrR mutants by nitrite.

Chromite oxidation by manganese oxides in subseafloor basalts and the presence of putative fossilized microorganisms.

PubMed

Ivarsson, Magnus; Broman, Curt; Holm, Nils G

2011-06-03

Chromite is a mineral with low solubility and is thus resistant to dissolution. The exception is when manganese oxides are available, since they are the only known naturally occurring oxidants for chromite. In the presence of Mn(IV) oxides, Cr(III) will oxidise to Cr(VI), which is more soluble than Cr(III), and thus easier to be removed. Here we report of chromite phenocrysts that are replaced by rhodochrosite (Mn(II) carbonate) in subseafloor basalts from the Koko Seamount, Pacific Ocean, that were drilled and collected during the Ocean Drilling Program (ODP) Leg 197. The mineral succession chromite-rhodochrosite-saponite in the phenocrysts is interpreted as the result of chromite oxidation by manganese oxides. Putative fossilized microorganisms are abundant in the rhodochrosite and we suggest that the oxidation of chromite has been mediated by microbial activity. It has previously been shown in soils and in laboratory experiments that chromium oxidation is indirectly mediated by microbial formation of manganese oxides. Here we suggest a similar process in subseafloor basalts.

Chromite oxidation by manganese oxides in subseafloor basalts and the presence of putative fossilized microorganisms

PubMed Central

2011-01-01

Chromite is a mineral with low solubility and is thus resistant to dissolution. The exception is when manganese oxides are available, since they are the only known naturally occurring oxidants for chromite. In the presence of Mn(IV) oxides, Cr(III) will oxidise to Cr(VI), which is more soluble than Cr(III), and thus easier to be removed. Here we report of chromite phenocrysts that are replaced by rhodochrosite (Mn(II) carbonate) in subseafloor basalts from the Koko Seamount, Pacific Ocean, that were drilled and collected during the Ocean Drilling Program (ODP) Leg 197. The mineral succession chromite-rhodochrosite-saponite in the phenocrysts is interpreted as the result of chromite oxidation by manganese oxides. Putative fossilized microorganisms are abundant in the rhodochrosite and we suggest that the oxidation of chromite has been mediated by microbial activity. It has previously been shown in soils and in laboratory experiments that chromium oxidation is indirectly mediated by microbial formation of manganese oxides. Here we suggest a similar process in subseafloor basalts. PMID:21639896

Characteristics of oxide scale formed on Cu-bearing austenitic stainless steel during early stages of high temperature oxidation

NASA Astrophysics Data System (ADS)

Swaminathan, Srinivasan; Krishna, Nanda Gopala; Kim, Dong-Ik

2015-10-01

Oxide scale evolution on Cu-bearing austenitic stainless steel 304H at 650 °C, in ambient air, for exposure times 100, 300, 500 and 1000 h, has been investigated. Surface morphology and chemistry of the oxide scale grown were examined using SEM/EDX and XPS. The oxidation kinetics was determined by measuring the weight change using an electronic balance. At the initial stage, up to 500 h of exposure time, the oxidation rate was rapid due to surface reactions governed primarily by oxygen ingress, and then, dropped to a low rate after prolonged oxidation for 1000 h. The diffusion of reactants through the initially formed oxide scale limits the oxidation rate at longer times, thus, the progress of reaction followed the parabolic kinetics. The formed oxide scale was enriched significantly with segregation and subsequent oxidation of Nb, and finely dispersed metallic Cu particles. Within the time frame of oxidation, the oxide scale was mainly composed of mixed oxides such as FeCr2O4 and MnCr2O4 along with the binary oxides of Fe, Cr and Mn. Moreover, the precipitation fraction of Cu-rich particles on the oxide scale increased markedly with increase of exposure times. The chemical heterogeneity of oxide scale suggests that the oxidation occurred in a non-selective manner.

Conduction mechanism change with transport oxide layer thickness in oxide hetero-interface diode

NASA Astrophysics Data System (ADS)

Nam, Bu-il; Park, Jong Seo; Lim, Keon-Hee; Ahn, Yong-keon; Lee, Jinwon; Park, Jun-woo; Cho, Nam-Kwang; Lee, Donggun; Lee, Han-Bo-Ram; Kim, Youn Sang

2017-07-01

An effective and facile strategy is proposed to demonstrate an engineered oxide hetero-interface of a thin film diode with a high current density and low operating voltage. The electrical characteristics of an oxide hetero-interface thin film diode are governed by two theoretical models: the space charge-limited current model and the Fowler-Nordheim (F-N) tunneling model. Interestingly, the dominant mechanism strongly depends on the insulator thickness, and the mechanism change occurs at a critical thickness. This paper shows that conduction mechanisms of oxide hetero-interface thin film diodes depend on thicknesses of transport oxide layers and that current densities of these can be exponentially increased through quantum tunneling in the diodes with the thicknesses less than 10 nm. These oxide hetero-interface diodes have great potential for low-powered transparent nanoscale applications.

Homology of vanadium oxide

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

Vasyutinskii, N.A.

1987-05-01

The authors examine the homology of vanadium oxide and note that data on the existence of phases and homogeneity limits in the V-O system are very contradictory. A graphical illustration shows the homologous series of vanadium oxides. The predominant part of the discrete formations in the system V-O is characterized by integral stoichiometry and forms six homologous series. It is found that homologous series of vanadium oxides are not only a basis for systematization of such oxides, but also may serve as a means for predicting the composition of new phases, limits of homogeneity, their structure, and properties.

Mixed oxide solid solutions

DOEpatents

Magno, Scott; Wang, Ruiping; Derouane, Eric

2003-01-01

The present invention is a mixed oxide solid solution containing a tetravalent and a pentavalent cation that can be used as a support for a metal combustion catalyst. The invention is furthermore a combustion catalyst containing the mixed oxide solid solution and a method of making the mixed oxide solid solution. The tetravalent cation is zirconium(+4), hafnium(+4) or thorium(+4). In one embodiment, the pentavalent cation is tantalum(+5), niobium(+5) or bismuth(+5). Mixed oxide solid solutions of the present invention exhibit enhanced thermal stability, maintaining relatively high surface areas at high temperatures in the presence of water vapor.

Photochemical water oxidation by crystalline polymorphs of manganese oxides: structural requirements for catalysis.

PubMed

Robinson, David M; Go, Yong Bok; Mui, Michelle; Gardner, Graeme; Zhang, Zhijuan; Mastrogiovanni, Daniel; Garfunkel, Eric; Li, Jing; Greenblatt, Martha; Dismukes, G Charles

2013-03-06

Manganese oxides occur naturally as minerals in at least 30 different crystal structures, providing a rigorous test system to explore the significance of atomic positions on the catalytic efficiency of water oxidation. In this study, we chose to systematically compare eight synthetic oxide structures containing Mn(III) and Mn(IV) only, with particular emphasis on the five known structural polymorphs of MnO2. We have adapted literature synthesis methods to obtain pure polymorphs and validated their homogeneity and crystallinity by powder X-ray diffraction and both transmission and scanning electron microscopies. Measurement of water oxidation rate by oxygen evolution in aqueous solution was conducted with dispersed nanoparticulate manganese oxides and a standard ruthenium dye photo-oxidant system. No Ru was absorbed on the catalyst surface as observed by XPS and EDX. The post reaction atomic structure was completely preserved with no amorphization, as observed by HRTEM. Catalytic activities, normalized to surface area (BET), decrease in the series Mn2O3 > Mn3O4 ≫ λ-MnO2, where the latter is derived from spinel LiMn2O4 following partial Li(+) removal. No catalytic activity is observed from LiMn2O4 and four of the MnO2 polymorphs, in contrast to some literature reports with polydispersed manganese oxides and electro-deposited films. Catalytic activity within the eight examined Mn oxides was found exclusively for (distorted) cubic phases, Mn2O3 (bixbyite), Mn3O4 (hausmannite), and λ-MnO2 (spinel), all containing Mn(III) possessing longer Mn-O bonds between edge-sharing MnO6 octahedra. Electronically degenerate Mn(III) has antibonding electronic configuration e(g)(1) which imparts lattice distortions due to the Jahn-Teller effect that are hypothesized to contribute to structural flexibility important for catalytic turnover in water oxidation at the surface.

The oxidation of carbon monoxide using tin oxide based catalysts

NASA Technical Reports Server (NTRS)

Sampson, Christopher F.; Jorgensen, Norman

1990-01-01

The preparation conditions for precious metal/tin oxide catalysts were optimized for maximum carbon monoxide/oxygen recombination efficiency. This was achieved by controlling the tin digestion, the peptization to form the sol, the calcination process and the method of adding the precious metals. Extensive studies of the tin oxide structure were carried out over the temperature range 20 to 500 C in air or hydrogen environments using Raman scattering and X ray diffraction. Adsorbed species on tin oxide, generated in an environment containing carbon monoxide, gave rise to a Raman band at about 1600 cm(exp -1) which was assigned to carbonaceous groups, possible carbonate.

Oxidative Weathering of Archean Sulfides: Implications for the Great Oxidation Event

NASA Astrophysics Data System (ADS)

Johnson, A.; Romaniello, S. J.; Reinhard, C.; Garcia-Robledo, E.; Revsbech, N. P.; Canfield, D. E.; Lyons, T. W.; Anbar, A. D.

2015-12-01

The first widely accepted evidence for oxidation of Earth's atmosphere and oceans occurs ~2.45 Ga immediately prior to the Great Oxidation Event (GOE). A major line of evidence for this transition includes the abundances and isotopic variations of redox-sensitive transition metals in marine sediments (e.g., Fe, Mo, Re, Cr, and U). It is often assumed that oxidative weathering is required to liberate these redox-sensitive elements from sulfide minerals in the crust, and hence that their presence in early Archean marine sediments signifies that oxidative weathering was stimulated by small and/or transient "whiffs" of O2 in the environment.1 However, studies of crustal sulfide reactivity have not been conducted at O2 concentrations as low as those that would have prevailed when O2 began its rise during the late Archean (estimated at <10-5 present atmospheric O2).2 As a result, it is difficult to quantify O2 concentrations implied by observed trace metal variations. As a first step toward providing more quantitative constraints on late Archean pO2, we conducted laboratory studies of pyrite and molybdenite oxidation kinetics at the nanomolar O2 concentrations that are relevant to late Archean environments. These measurements were made using recently developed, highly sensitive optical O2 sensors to monitor the rates at which the powdered minerals consumed dissolved O2 in a range of pH-buffered solutions.3Our data extend the range of experimental pyrite oxidation rates in the literature by three orders of magnitude from ~10-3 present atmospheric O2 to ~10-6. We find that molybdenite and pyrite oxidation continues to <1 nM O2 (4 x 10-6 present atmospheric O2). This implies that oxidative weathering of sulfides could occur under conditions which preserve MIF S fractionation. Furthermore, our results indicate that the rate law and reaction order of pyrite oxidation kinetics change significantly at nanomolar concentrations of O2 when compared to previous compilations.2 Our

Metal oxide nanorod arrays on monolithic substrates

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

Gao, Pu-Xian; Guo, Yanbing; Ren, Zheng

A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can includemore » a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod. Structures can be bonded to the surface of a substrate and resist erosion if exposed to high velocity flow rates.« less

Characterization of a transient +2 sulfur oxidation state intermediate from the oxidation of aqueous sulfide

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

Vairavmurthy, M.A.; Zhou, Weiqing

1995-04-01

The oxidation H{sub 2}S to sulfate involves a net transfer of eight electrons and occurs through the formation of several partially oxidized intermediates with oxidation states ranging from {minus}1 to +5. Known intermediates include elemental sulfur (oxidation state 0), polysulfides (outer sulfur: {minus}1, inner sulfur: 0), sulfite (+4) and thiosulfate (outer sulfur: {minus}1, inner sulfur: +5). A noticeable gap in this series of intermediates is that of a +2 sulfur oxidation state oxoacid/oxoanion species, which was never detected experimentally. Here, we present evidence of the transient existence of +2 oxidation state intermediate in the Ni(II)-catalyzed oxidation of aqueous sulfide. X-raymore » absorption near-edge structure (XANES) spectroscopy and Fourier-transform-infrared (FT-IR) spectroscopy were used to characterize this species; they suggest that it has a sulfoxylate ion (SO{sub 2}{sup 2{minus}}) structure.« less

Resistive and Capacitive Memory Effects in Oxide Insulator/ Oxide Conductor Hetero-Structures

NASA Astrophysics Data System (ADS)

Meyer, Rene; Miao, Maosheng; Wu, Jian; Chevallier, Christophe

2013-03-01

We report resistive and capacitive memory effects observed in oxide insulator/ oxide conductor hetero-structures. Electronic transport properties of Pt/ZrO2/PCMO/Pt structures with ZrO2 thicknesses ranging from 20A to 40A are studied before and after applying short voltage pulses of positive and negative polarity for set and reset operation. As processed devices display a non-linear IV characteristic which we attribute to trap assisted tunneling through the ZrO2 tunnel oxide. Current scaling with electrode area and tunnel oxide thickness confirms uniform conduction. The set/reset operation cause an up/down shift of the IV characteristic indicating that the conduction mechanism of both states is still dominated by tunneling. A change in the resistance is associated with a capacitance change of the device. An exponential relation between program voltages and set times is found. A model based on electric field mediated non-linear transport of oxygen ions across the ZrO2/PCMO interface is proposed. The change in the tunnel current is explained by ionic charge transfer between tunnel oxide and conductive metal oxide changing both tunnel barrier height and PCMO conductivity. DFT techniques are employed to explain the conductivity change in the PCMO interfacial layer observed through capacitance measurements.

Method of fabricating conducting oxide-silicon solar cells utilizing electron beam sublimation and deposition of the oxide

DOEpatents

Feng, Tom; Ghosh, Amal K.

1979-01-01

In preparing tin oxide and indium tin oxide-silicon heterojunction solar cells by electron beam sublimation of the oxide and subsequent deposition thereof on the silicon, the engineering efficiency of the resultant cell is enhanced by depositing the oxide at a predetermined favorable angle of incidence. Typically the angle of incidence is between 40.degree. and 70.degree. and preferably between 55.degree. and 65.degree. when the oxide is tin oxide and between 40.degree. and 70.degree. when the oxide deposited is indium tin oxide. gi The Government of the United States of America has rights in this invention pursuant to Department of Energy Contract No. EY-76-C-03-1283.

Reduction of graphene oxide by aniline with its concomitant oxidative polymerization.

PubMed

Xu, Li Qun; Liu, Yi Liang; Neoh, Koon-Gee; Kang, En-Tang; Fu, Guo Dong

2011-04-19

Graphene oxide (GO) nanosheets are readily reduced by aniline above room temperature in an aqueous acid medium, with the aniline simultaneously undergoing oxidative polymerization to produce the reduced graphene oxide-polyaniline nanofiber (RGO-PANi) composites. The resulting RGO-PANi composites and RGO (after dissolution of PANi) were characterized by XPS, XRD analysis, TGA, UV-visible absorption spectroscopy, and TEM. It was also found that the RGO-PANi composites exhibit good specific capacitance during galvanostatic charging-discharging when used as capacitor electrodes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lipid oxidation. Part 2. Oxidation products of olive oil methyl esters.

PubMed

Pokorný, J; Tài, P; Parízková, H; Smidrkalová, E; El-Tarras, M F; Janícek, G

1976-01-01

Olive oil was converted into methyl esters which were autoxidized at 60 degrees C. The composition of oxidized products was determined by the comparison of infrared spectra and NMR spectra of the original and acetylated samples, the sample reduced with potassium iodide and the acetylated reduced sample. Oxidized products were separated by preparative thin layer chromatography on silica gel and characterized by selective detection and by infrared spectrometry of the fractions. The oxidation products consisted of hydroperoxido butyl oleate, substituted hydroperoxides, mono- and disubstituted monomeric derivatives and a small amount of oligomers.

Pro-Oxidant Biological Effects of Inorganic Component of Petroleum: Vanadium and Oxidative Stress

DTIC Science & Technology

1996-08-01

independent existence. Pro-Oxidant Chemicals and Free Radicals Involved in Oxidative Stress Pro-Oxidant Chemicals Chemical and Metabolic Generation... metabolic reactions may generate primary free radicals (Fig. 1). Then, in an avalanche-type process, secondary free radicals and reactive oxygen species...vanadium absorption, distribution, metabolism , and disposition, and no pharmacokinetic model is available describing comparative kinetics and toxicity

Evolution of Near-Surface Internal and External Oxide Morphology During High-Temperature Selective Oxidation of Steels

NASA Astrophysics Data System (ADS)

Story, Mary E.; Webler, Bryan A.

2018-05-01

In this work we examine some observations made using high-temperature confocal scanning laser microscopy (HT-CSLM) during selective oxidation experiments. A plain carbon steel and advanced high-strength steel (AHSS) were selectively oxidized at high temperature (850-900°C) in either low oxygen or water vapor atmospheres. Surface evolution, including thermal grooving along grain boundaries and oxide growth, was viewed in situ during heating. Experiments investigated the influence of the microstructure and oxidizing atmosphere on selective oxidation behavior. Sequences of CSLM still frames collected during the experiment were processed with ImageJ to obtain histograms that showed a general darkening trend indicative of oxidation over time with all samples. Additional ex situ scanning electron microscopy and energy dispersive spectroscopy analysis supported in situ observations. Distinct oxidation behavior was observed for each case. Segregation, grain orientation, and extent of internal oxidation were all found to strongly influence surface evolution.

RELATIONSHIPS BETWEEN OXIDATION-REDUCTION POTENTIAL, OXIDANT, AND PH IN DRINKING WATER

EPA Science Inventory

Oxidation and reduction (redox) reactions are very important in drinking water. Oxidation-reduction potential (ORP) measurements reflect the redox state of water. Redox measurements are not widely made by drinking water utilities in part because they are not well understood. The ...

Reduction in the Band Gap of Manganese-Doped Zinc Oxide: Role of the Oxidation State

NASA Astrophysics Data System (ADS)

Sharma, Sonia; Ramesh, Pranith; Swaminathan, P.

2015-12-01

Manganese-doped zinc oxide powders were synthesized by solid state reaction of the respective oxides. The high-temperature conditions were chosen such that multiple valence states of manganese were doped in the host zinc oxide lattice. Structural characterization was carried out to confirm the doping and to find the maximum amount of manganese that can be incorporated. Diffuse reflectance spectroscopy was used to measure the optical band gap of the doped sample and the lowering with respect to pure ZnO was attributed to the presence of higher oxidation states of manganese. The presence of these oxidation states was confirmed using x-ray photoelectron spectroscopy. The study shows that a solid state reaction is a viable route for synthesizing doped metal oxides with desired optical properties.

Cordierite-supported metal oxide for non-methane hydrocarbon oxidation in cooking oil fumes.

PubMed

Huang, Yonghai; Yi, Honghong; Tang, Xiaolong; Zhao, Shunzheng; Gao, Fengyu; Wang, Jiangen; Yang, Zhongyu

2018-05-21

Cooking emission is an important reason for the air quality deterioration in the metropolitan area in China. Transition metal oxide and different loading of manganese oxide supported on cordierite were prepared by incipient wetness impregnation method and were used for non-methane hydrocarbon (NMHC) oxidation in cooking oil fumes (COFs). The effects of different calcination temperature and different Mn content were also studied. The SEM photographs and CO 2 temperature-programmed desorption revealed 5 wt% Mn/cordierite had the best pore structure and the largest number of the weak and moderate basic sites so it showed the best performance for NMHC oxidation. XRD analysis exhibited 5 wt% Mn/cordierite had the best dispersion of active phase and the active phase was MnO 2 when the calcination temperature was 400℃ which were good for the catalytic oxidation of NMHC.

Metal oxide composite enabled nanotextured Si photoanode for efficient solar driven water oxidation.

PubMed

Sun, Ke; Pang, Xiaolu; Shen, Shaohua; Qian, Xueqiang; Cheung, Justin S; Wang, Deli

2013-05-08

We present a study of a transition metal oxide composite modified n-Si photoanode for efficient and stable water oxidation. This sputter-coated composite functions as a protective coating to prevent Si from photodecomposition, a Schottky heterojunction, a hole conducting layer for efficient charge separation and transportation, and an electrocatalyst to reduce the reaction overpotential. The formation of mixed-valence oxides composed of Ni and Ru effectively modifies the optical, electrical, and catalytic properties of the coating material, as well as the interfaces with Si. The successful application of this oxide composite on nanotextured Si demonstrates improved conversion efficiency due to enhanced catalytic activity, minimized reflection, and increased surface reaction sites. Although the coated nanotextured Si shows a noticeable degradation from 500 cycles of operation, the oxide composite provides a simple method to enable unstable photoanode materials for solar fuel conversion.

Water Oxidation Mechanisms of Metal Oxide Catalysts by Vibrational Spectroscopy of Transient Intermediates.

PubMed

Zhang, Miao; Frei, Heinz

2017-05-05

Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements. Recent dynamic infrared and Raman studies reveal the molecular identity of transient surface intermediates of water oxidation on metal oxides. Combined with ultrafast infrared observations of how charges are delivered to active sites of the metal oxide catalyst and drive the multielectron reaction, spectroscopic advances are poised to play a key role in accelerating progress toward improved catalysts for artificial photosynthesis.

[Increasing oxidative stress in aging].

PubMed

Shimosawa, Tatsuo

2005-06-01

The balance between reactive oxigen species (ROS) production and degradation is important in defining oxidative stress. In aging process, ROS production increases and degradation is impaired and thus oxidative stress is accumulated. Oxidative stress damages organs both directly and indirectly. Protein, lipid, as well as DNA are directly react with ROS, more over, ROS interact with intracellular signaling system. It is reported that several transcription factors such as NF-kappaB, AP-1 and ASK-1 and also it interferes MAPK activity. Besides these signaling, we recently showed that insulin resistance is induced by accumulated oxidative stress in aged mice. Adrenomedullin deficient mice accumulate higher oxidative stress and insulin resistance developed in aging. Oxidative stress in aging relates not only direct organ damage but also induce risk factors for vascular damage such as metabolic syndrome.

Aspirin increases mitochondrial fatty acid oxidation

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

Uppala, Radha; Dudiak, Brianne; Beck, Megan E.

The metabolic effects of salicylates are poorly understood. This study investigated the effects of aspirin on fatty acid oxidation. Aspirin increased mitochondrial long-chain fatty acid oxidation, but inhibited peroxisomal fatty acid oxidation, in two different cell lines. Aspirin increased mitochondrial protein acetylation and was found to be a stronger acetylating agent in vitro than acetyl-CoA. However, aspirin-induced acetylation did not alter the activity of fatty acid oxidation proteins, and knocking out the mitochondrial deacetylase SIRT3 did not affect the induction of long-chain fatty acid oxidation by aspirin. Aspirin did not change oxidation of medium-chain fatty acids, which can freely traverse themore » mitochondrial membrane. Together, these data indicate that aspirin does not directly alter mitochondrial matrix fatty acid oxidation enzymes, but most likely exerts its effects at the level of long-chain fatty acid transport into mitochondria. The drive on mitochondrial fatty acid oxidation may be a compensatory response to altered mitochondrial morphology and inhibited electron transport chain function, both of which were observed after 24 h incubation of cells with aspirin. These studies provide insight into the pathophysiology of Reye Syndrome, which is known to be triggered by aspirin ingestion in patients with fatty acid oxidation disorders. - Highlights: • Aspirin increases mitochondrial—but inhibits peroxisomal—fatty acid oxidation. • Aspirin acetylates mitochondrial proteins including fatty acid oxidation enzymes. • SIRT3 does not influence the effect of aspirin on fatty acid oxidation. • Increased fatty acid oxidation is likely due to altered mitochondrial morphology and respiration.« less

OXIDATION OF TRANSURANIC ELEMENTS

DOEpatents

Moore, R.L.

1959-02-17

A method is reported for oxidizing neptunium or plutonium in the presence of cerous values without also oxidizing the cerous values. The method consists in treating an aqueous 1N nitric acid solution, containing such cerous values together with the trivalent transuranic elements, with a quantity of hydrogen peroxide stoichiometrically sufficient to oxidize the transuranic values to the hexavalent state, and digesting the solution at room temperature.

Oxidation of dimethylselenide by δMnO2: oxidation product and factors affecting oxidation rate

USGS Publications Warehouse

Wang, Bronwen; Burau, Richard G.

1995-01-01

Volatile dimethylselenide (DMSe) was transformed to a nonvolatile Se compound in a ??-MnO2 suspension. The nonvolatile product was a single compound identified as dimethylselenoxide based on its mass spectra pattern. After 24 h, 100% of the DMSe added to a ??-MnO2 suspension was converted to nonpurgable Se as opposed to 20%, 18%, and 4% conversion for chromate, permanganate, and the filtrate from the suspension, respectively. Manganese was found in solution after reaction. These results imply that the reaction between manganese oxide and DMSe was a heterogeneous redox reaction involving solid phase ??-MnO2 and solution phase DMSe. Oxidation of DMSe to dimethylselenoxide [OSe(CH3)2] by a ??-MnO2 suspension appears to be first order with respect to ??-MnO2, to DMSe, and to hydrogen ion with an overall rate law of d[OSe(CH3)2 ]/dt = 95 M-2 min-1 [MnO2]1[DMSe]1[H+]1 for the MnO2 concentration range of 0.89 ?? 10-3 - 2.46 ?? 10-3 M, the DMSe concentration range of 3.9 ?? 10-7 - 15.5 ?? 10-7 M Se, and a hydrogen ion concentation range of 7.4 ?? 10-6 -9.5 ?? 10-8 M. A general surface site adsorption model is consistent with this rate equation if the uncharged |OMnOH is the surface adsorption site. DMSe acts as a Lewis base, and the manganese oxide surface acts as a Lewis acid. DMSe adsorption to |OMnOH can be viewed as a Lewis acid/ base complex between the largely p orbitals of the DMSe lone pair and the unoccupied eg orbitals on manganese oxide. For such a complex, frontier molecular orbital theory predicts electron transfer to occur via an inner-sphere complex between the DMSe and the manganese oxide. ?? 1995 American Chemical Society.

The development of latent fingerprints by zinc oxide and tin oxide nanoparticles prepared by precipitation technique

NASA Astrophysics Data System (ADS)

Luthra, Deepali; Kumar, Sacheen

2018-05-01

Fingerprints are the very important evidence at the crime scene which must be developed clearly with shortest duration of time to solve the case. Metal oxide nanoparticles could be the mean to develop the latent fingerprints. Zinc oxide and Tin Oxide Nanoparticles were prepared by using chemical precipitation technique which were dried and characterized by X-ray diffraction, UV-Visible spectroscopy and FTIR. The size of zinc oxide crystallite was found to be 14.75 nm with minimum reflectance at 360 nm whereas tin oxide have the size of 90 nm and reflectance at minimum level 321 nm. By using these powdered samples on glass, plastic and glossy cardboard, latent fingerprints were developed. Zinc oxide was found to be better candidate than tin oxide for the fingerprint development on all the three types of substrates.

Understanding complete oxidation of methane on spinel oxides at a molecular level

DOE PAGES

Tao, Franklin Feng; Shan, Jun-jun; Nguyen, Luan; ...

2015-08-04

It is crucial to develop a catalyst made of earth-abundant elements highly active for a complete oxidation of methane at a relatively low temperature. NiCo 2O 4 consisting of earth-abundant elements which can completely oxidize methane in the temperature range of 350-550 °C. Being a cost-effective catalyst, NiCo 2O 4 exhibits activity higher than precious-metal-based catalysts. Here we report that the higher catalytic activity at the relatively low temperature results from the integration of nickel cations, cobalt cations and surface lattice oxygen atoms/oxygen vacancies at the atomic scale. Finally, in situ studies of complete oxidation of methane on NiCo 2Omore » 4 and theoretical simulations show that methane dissociates to methyl on nickel cations and then couple with surface lattice oxygen atoms to form -CH 3O with a following dehydrogenation to -CH 2O; a following oxidative dehydrogenation forms CHO; CHO is transformed to product molecules through two different sub-pathways including dehydrogenation of OCHO and CO oxidation.« less

Biogeochemistry of Fe(II) oxidation in a photosynthetic microbial mat: Implications for Precambrian Fe(II) oxidation

NASA Astrophysics Data System (ADS)

Trouwborst, Robert E.; Johnston, Anne; Koch, Gretchen; Luther, George W.; Pierson, Beverly K.

2007-10-01

We studied the role of microbial photosynthesis in the oxidation of Fe(II) to Fe(III) in a high Fe(II) and high Mn(II) hot spring devoid of sulfide and atmospheric oxygen in the source waters. In situ light and dark microelectrode measurements of Fe(II), Mn(II) and O 2 were made in the microbial mat consisting of cyanobacteria and anoxygenic photosynthetic Chloroflexus sp. We show that Fe(II) oxidation occurred when the mat was exposed to varying intensities of sunlight but not near infrared light. We did not observe any Mn(II) oxidation under any light or dark condition over the pH range 5-7. We observed the impact of oxygenic photosynthesis on Fe(II) oxidation, distinct from the influence of atmospheric O 2 and anoxygenic photosynthesis. In situ Fe(II) oxidation rates in the mats and cell suspensions exposed to light are consistent with abiotic oxidation by O 2. The oxidation of Fe(II) to form primary Fe(III) phases contributed to banded iron-formations (BIFs) during the Precambrian. Both oxygenic photosynthesis, which produces O 2 as an oxidizing waste product, and anoxygenic photosynthesis in which Fe(II) is used to fix CO 2 have been proposed as Fe(II) oxidation mechanisms. Although we do not know the specific mechanisms responsible for all Precambrian Fe(II) oxidation, we assessed the relative importance of both mechanisms in this modern hot spring environment. In this environment, cyanobacterial oxygen production accounted for all the observed Fe(II) oxidation. The rate data indicate that a modest population of cyanobacteria could have mediated sufficient Fe(II) oxidation for some BIFs.

Operation of staged membrane oxidation reactor systems

DOEpatents

Repasky, John Michael

2012-10-16

A method of operating a multi-stage ion transport membrane oxidation system. The method comprises providing a multi-stage ion transport membrane oxidation system with at least a first membrane oxidation stage and a second membrane oxidation stage, operating the ion transport membrane oxidation system at operating conditions including a characteristic temperature of the first membrane oxidation stage and a characteristic temperature of the second membrane oxidation stage; and controlling the production capacity and/or the product quality by changing the characteristic temperature of the first membrane oxidation stage and/or changing the characteristic temperature of the second membrane oxidation stage.

Nitrous oxide and perioperative outcomes.

PubMed

Ko, Hanjo; Kaye, Alan David; Urman, Richard D

2014-06-01

There is emerging evidence related to the effects of nitrous oxide on important perioperative patient outcomes. Proposed mechanisms include metabolic effects linked to elevated homocysteine levels and endothelial dysfunction, inhibition of deoxyribonucleic acid and protein formation, and depression of chemotactic migration by monocytes. Newer large studies point to possible risks associated with the use of nitrous oxide, although data are often equivocal and inconclusive. Cardiovascular outcomes such as stroke or myocardial infarction were shown to be unchanged in previous studies, but the more recent Evaluation of Nitrous Oxide in the Gas Mixture for Anesthesia I trial shows possible associations between nitrous oxide and increased cardiovascular and pulmonary complications. There are also possible effects on postoperative wound infections and neuropsychological function, although the multifactorial nature of these complications should be considered. Teratogenicity linked to nitrous oxide use has not been firmly established. The use of nitrous oxide for routine anesthetic care may be associated with significant costs if complications such as nausea, vomiting, and wound infections are taken into consideration. Overall, definitive data regarding the effect of nitrous oxide on major perioperative outcomes are lacking. There are ongoing prospective studies that may further elucidate its role. The use of nitrous oxide in daily practice should be individualized to each patient's medical conditions and risk factors.

Nanoparticle-induced oxidation of corona proteins initiates an oxidative stress response in cells†

PubMed Central

Jayaram, Dhanya T.; Runa, Sabiha; Kemp, Melissa L.

2017-01-01

Titanium dioxide nanoparticles (TiO2 NPs), used as pigments and photocatalysts, are ubiquitous in our daily lives. Previous work has observed cellular oxidative stress in response to the UV-excitation of photocatalytic TiO2 NPs. In comparison, most human exposure to TiO2 NPs takes place in the dark, in the lung following inhalation or in the gut following consumption of TiO2 NP food pigment. Our spectroscopic characterization shows that both photocatalytic and food grade TiO2 NPs, in the dark, generate low levels of reactive oxygen species (ROS), specifically hydroxyl radicals and superoxides. These ROS oxidize serum proteins that form a corona of proteins on the NP surface. This protein layer is the interface between the NP and the cell. An oxidized protein corona triggers an oxidative stress response, detected with PCR and western blotting. Surface modification of TiO2 NPs to increase or decrease surface defects correlates with ROS generation and oxidative stress, suggesting that NP surface defects, likely oxygen vacancies, are the underlying cause of TiO2 NP-induced oxidative stress. PMID:28537609

Mechanism for the oxidation of phenol by sulfatoferrate(VI): Comparison with various oxidants.

PubMed

Peings, Vanessa; Frayret, Jérôme; Pigot, Thierry

2015-07-01

The oxidative action of a solid and stable potassium sulfatoferrate(VI) material on phenol was studied in aqueous solution under different stoichiometries. The performance towards phenol and the total organic carbon is compared to that of potassium permanganate and calcium hypochlorite. The total mineralization of phenol is not completely achieved by the studied chemical oxidants, and some oxidation products have been identified by gas chromatography-mass spectrometry and gas chromatography-flame ionization detector analysis. A radical reaction pathway, involving the formation of oxidation intermediates or by-products such as benzoquinone, phenoxyphenol and ring opening products, is proposed for the decomposition of phenol by ferrate(VI). Phenoxyphenol is also involved in the oxidation mechanism for permanganate whereas chlorinated phenols are produced by hypochlorite. The role of the chloride anion impurity of the potassium sulfatoferrate(VI) material has been highlighted in this study; no negative impact on the removal of phenol and its mineralization is observed compared to the use of a pure commercial ferrate(VI). The efficiency of sulfatoferrate(VI) for the oxidative removal of phenol from industrial wastewater is also confirmed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Characterization of Rhenium Oxides Using ESCA

NASA Technical Reports Server (NTRS)

Panda, Binayak; Gentz, Steven J. (Technical Monitor)

2001-01-01

High melting point and inherent ductility (toughness) over a wide range of temperature has made Rhenium an engineering material of choice for several thrust chambers in propulsion systems. Although the material remains tough at high temperatures, it still can readily transform to several oxides. As many as eight different oxides have been reported in literature. When characterized using ESCA (Electron Spectroscopy for Chemical Analyses) these oxides show large shifts in the Re 4f line positions. While this unique property could be used as a tool for oxide characterization, literature indicates that only a few of these oxides have been characterized. Current work focuses on characterizing oxides of Rhenium using ESCA. Spectral line Re 4f have been measured for various oxides and the results have been compared with the Re 4f line positions of real-time oxidation products from space hardware.

Methods for synthesizing metal oxide nanowires

DOEpatents

Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

2016-08-09

A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

Method of removing oxides of sulfur and oxides of nitrogen from exhaust gases

DOEpatents

Walker, Richard J.

1986-01-01

A continuous method is presented for removing both oxides of sulfur and oxides of nitrogen from combustion or exhaust gases with the regeneration of the absorbent. Exhaust gas is cleaned of particulates and HCl by a water scrub prior to contact with a liquid absorbent that includes an aqueous solution of bisulfite and sulfite ions along with a metal chelate, such as, an iron or zinc aminopolycarboxylic acid. Following contact with the combustion gases the spent absorbent is subjected to electrodialysis to transfer bisulfite ions into a sulfuric acid solution while splitting water with hydroxide and hydrogen ion migration to equalize electrical charge. The electrodialysis stack includes alternate layers of anion selective and bipolar membranes. Oxides of nitrogen are removed from the liquid absorbent by air stripping at an elevated temperature and the regenerated liquid absorbent is returned to contact with exhaust gases for removal of sulfur oxides and nitrogen oxides.

Charge transfer in rectifying oxide heterostructures and oxide access elements in ReRAM

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

Stefanovich, G. B.; Pergament, A. L.; Boriskov, P. P.

2016-05-15

The main aspects of the synthesis and experimental research of oxide diode heterostructures are discussed with respect to their use as selector diodes, i.e., access elements in oxide resistive memory. It is shown that charge transfer in these materials differs significantly from the conduction mechanism in p–n junctions based on conventional semiconductors (Si, Ge, A{sup III}–B{sup V}), and the model should take into account the electronic properties of oxides, primarily the low carrier drift mobility. It is found that an increase in the forward current requires an oxide with a small band gap (<1.3 eV) in the heterostructure composition. Heterostructuresmore » with Zn, In–Zn (IZO), Ti, Ni, and Cu oxides are studied; it is found that the CuO–IZO heterojunction has the highest forward current density (10{sup 4} A/cm{sup 2}).« less

Oxidation of diesel soot on binary oxide CuCr(Co)-based monoliths.

PubMed

Soloviev, Sergiy O; Kapran, Andriy Y; Kurylets, Yaroslava P

2015-02-01

Binary oxide systems (CuCr2O4, CuCo2O4), deposited onto cordierite monoliths of honeycomb structure with a second support (finely dispersed Al2O3), were prepared as filters for catalytic combustion of diesel soot using internal combustion engine's gas exhausts (O2, NOx, H2O, CO2) and O3 as oxidizing agents. It is shown that the second support increases soot capacity of aforementioned filters, and causes dispersion of the particles of spinel phases as active components enhancing thereby catalyst activity and selectivity of soot combustion to CO2. Oxidants used can be arranged with reference to decreasing their activity in a following series: O3≫NO2>H2O>NO>O2>CO2. Ozone proved to be the most efficient oxidizing agent: the diesel soot combustion by O3 occurs intensively (in the presence of copper chromite based catalyst) even at closing to ambient temperatures. Results obtained give a basis for the conclusion that using a catalytic coating on soot filters in the form of aforementioned binary oxide systems and ozone as the initiator of the oxidation processes is a promising approach in solving the problem of comprehensive purification of automotive exhaust gases at relatively low temperatures, known as the "cold start" problem. Copyright © 2014. Published by Elsevier B.V.

Long-Term Stability of Oxide Nanowire Sensors via Heavily Doped Oxide Contact.

PubMed

Zeng, Hao; Takahashi, Tsunaki; Kanai, Masaki; Zhang, Guozhu; He, Yong; Nagashima, Kazuki; Yanagida, Takeshi

2017-12-22

Long-term stability of a chemical sensor is an essential quality for long-term collection of data related to exhaled breath, environmental air, and other sources in the Internet of things (IoT) era. Although an oxide nanowire sensor has shown great potential as a chemical sensor, the long-term stability of sensitivity has not been realized yet due to electrical degradation under harsh sensing conditions. Here, we report a rational concept to accomplish long-term electrical stability of metal oxide nanowire sensors via introduction of a heavily doped metal oxide contact layer. Antimony-doped SnO 2 (ATO) contacts on SnO 2 nanowires show much more stable and lower electrical contact resistance than conventional Ti contacts for high temperature (200 °C) conditions, which are required to operate chemical sensors. The stable and low contact resistance of ATO was confirmed for at least 1960 h under 200 °C in open air. This heavily doped oxide contact enables us to realize the long-term stability of SnO 2 nanowire sensors while maintaining the sensitivity for both NO 2 gas and light (photo) detections. The applicability of our method is confirmed for sensors on a flexible polyethylene naphthalate (PEN) substrate. Since the proposed fundamental concept can be applied to various oxide nanostructures, it will give a foundation for designing long-term stable oxide nanomaterial-based IoT sensors.

PREPARATION OF REFRACTORY OXIDE MICROSPHERE

DOEpatents

Haws, C.C. Jr.

1963-09-24

A method is described of preparing thorium oxide in the form of fused spherical particles about 1 to 2 microns in diameter. A combustible organic solution of thorium nitrate containing additive metal values is dispersed into a reflected, oxygen-fed flame at a temperature above the melting point of the resulting oxide. The metal additive is aluminum at a proportion such as to provide 1 to 10 weight per cent aluminum oxide in the product, silicon at the same proportion, or beryllium at a proportion of 12 to 25 weight per cent beryllium oxide in the product. A minor proportion of uranium values may also be provided in the solution. The metal additive lowers the oxide melting point and allows fusion and sphere formation in conventional equipment. The product particles are suitable for use in thorium oxide slurries for nuclear reactors. (AEC)