iron silicide nanoprecipitates: Topics by WorldWideScience.org

Sample records for iron silicide nanoprecipitates

Immobilization of Uranium Silicide in Sintered Iron-Phosphate Glass

International Nuclear Information System (INIS)

Mateos, Patricia; Russo, Diego; Rodriguez, Diego; Heredia, A; Sanfilippo, M.; Sterba, Mario

2003-01-01

This work is a continuation of a previous one performed in vitrification of uranium silicide in borosilicate and iron-silicate glasses, by sintering.We present the results obtained with an iron-phosphate glass developed at our laboratory and we compare this results with those obtained with the above mentioned glasses. The main objective was to develop a method as simple as possible, so as to get a monolithic glass block with the appropriate properties to be disposed in a deep geological repository.The thermal transformation of the uranium silicide was characterized by DTA/TG analysis and X-ray diffraction.We determined the evolution of the crystalline phases and the change in weight.Calcined uranium silicide was mixed with natural U 3 O 8 , the amount of U 3 O 8 was calculated to simulate an isotopic dilution of 4%.This material was mixed with powdered iron-phosphate glass (in wt.%: 64,9 P 2 O 5 ; 22,7 Fe 2 O 3 ; 8,1 Al 2 O 3 ; 4,3 Na 2 O) in different proportions (in wt%): 7%, 10% y 15%.The powders were pressed and sintered at temperatures between 585 y 670 °C. Samples of the sintered pellet were prepared for the lixiviation tests (MCC-1P: monolithic samples; deionised water; 90° C; 7, 14 and 28 days).The samples showed a quite good durability (0,6 g.m -2 .day -1 ), similar to borosilicate glasses.The microstructure of the glass samples showed that the uranium particles are much better integrated to the glass matrix in the iron-phosphate glasses than in the borosilicate or iron-silicate glasses.We can conclude that the sintered product obtained could be a good alternative for the immobilization of nuclear wastes with high content of uranium, as the ones arising from the conditioning of research reactors spent fuels
Self-organized patterns along sidewalls of iron silicide nanowires on Si(110) and their origin

Energy Technology Data Exchange (ETDEWEB)

Das, Debolina; Mahato, J. C.; Bisi, Bhaskar; Dev, B. N., E-mail: msbnd@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Kolkata 700032 (India); Satpati, B. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)

2014-11-10

Iron silicide (cubic FeSi{sub 2}) nanowires have been grown on Si(110) by reactive deposition epitaxy and investigated by scanning tunneling microscopy and scanning/transmission electron microscopy. On an otherwise uniform nanowire, a semi-periodic pattern along the edges of FeSi{sub 2} nanowires has been discovered. The origin of such growth patterns has been traced to initial growth of silicide nanodots with a pyramidal Si base at the chevron-like atomic arrangement of a clean reconstructed Si(110) surface. The pyramidal base evolves into a comb-like structure along the edges of the nanowires. This causes the semi-periodic structure of the iron silicide nanowires along their edges.
Quantitative EPMA of Nano-Phase Iron-Silicides in Apollo 16 Lunar Regolith

Science.gov (United States)

Gopon, P.; Fournelle, J.; Valley, J. W.; Pinard, P. T.; Sobol, P.; Horn, W.; Spicuzza, M.; Llovet, X.; Richter, S.

2013-12-01

Until recently, quantitative EPMA of phases under a few microns in size has been extremely difficult. In order to achieve analytical volumes to analyze sub-micron features, accelerating voltages between 5 and 8 keV need to be used. At these voltages the normally used K X-ray transitions (of higher Z elements) are no longer excited, and we must rely of outer shell transitions (L and M). These outer shell transitions are difficult to use for quantitative EPMA because they are strongly affected by different bonding environments, the error associated with their mass attenuation coefficients (MAC), and their proximity to absorption edges. These problems are especially prevalent for the transition metals, because of the unfilled M5 electron shell where the Lα transition originates. Previous studies have tried to overcome these limitations by using standards that almost exactly matched their unknowns. This, however, is cumbersome and requires accurate knowledge of the composition of your sample beforehand, as well as an exorbitant number of well characterized standards. Using a 5 keV electron beam and utilizing non-standard X-ray transitions (Ll) for the transition metals, we are able to conduct accurate quantitative analyses of phases down to ~300nm. The Ll transition in the transition metals behaves more like a core-state transition, and unlike the Lα/β lines, is unaffected by bonding effects and does not lie near an absorption edge. This allows for quantitative analysis using standards do not have to exactly match the unknown. In our case pure metal standards were used for all elements except phosphorus. We present here data on iron-silicides in two Apollo 16 regolith grains. These plagioclase grains (A6-7 and A6-8) were collected between North and South Ray Craters, in the lunar highlands, and thus are associated with one or more large impact events. We report the presence of carbon, nickel, and phosphorus (in order of abundance) in these iron-silicide phases
Ferromagnetic properties of manganese doped iron silicide

Science.gov (United States)

Ruiz-Reyes, Angel; Fonseca, Luis F.; Sabirianov, Renat

We report the synthesis of high quality Iron silicide (FeSi) nanowires via Chemical Vapor Deposition (CVD). The materials exhibits excellent magnetic response at room temperature, especially when doped with manganese showing values of 2.0 X 10-04 emu for the FexMnySi nanowires. SEM and TEM characterization indicates that the synthesized nanowires have a diameter of approximately 80nm. MFM measurements present a clear description of the magnetic domains when the nanowires are doped with manganese. Electron Diffraction and XRD measurements confirms that the nanowires are single crystal forming a simple cubic structure with space group P213. First-principle calculations were performed on (111) FeSi surface using the Vienna ab initio simulation package (VASP). The exchange correlations were treated under the Ceperley-Alder (CA) local density approximation (LDA). The Brillouin Zone was sampled with 8x8x1 k-point grid. A total magnetic moment of about 10 μB was obtained for three different surface configuration in which the Iron atom nearest to the surface present the higher magnetization. To study the effect of Mn doping, Fe atom was replaced for a Mn. Stronger magnetization is presented when the Mn atom is close to the surface. The exchange coupling constant have been evaluated calculating the energy difference between the ferromagnetic and anti-ferromagnetic configurations.
Morphological and electrical properties of self-assembled iron silicide nanoparticles on Si(0 0 1) and Si(1 1 1) substrates

International Nuclear Information System (INIS)

Molnár, G.; Dózsa, L.; Erdélyi, R.; Vértesy, Z.; Osváth, Z.

2015-01-01

Highlights: • Epitaxial iron silicide nanostructures were grown on Si(1 1 1) and Si(0 0 1) substrates. • The size and shape of the particles are the function of the thickness and annealing. • The local current–voltage characteristics were measured by conductive AFM. • The different size and shape nanoparticles show similar I–V characteristics. • The tip current is dominated in few nm size sites, visible in the AFM phase image. - Abstract: Epitaxial iron silicide nanostructures are grown by solid phase epitaxy on Si(0 0 1) and Si(1 1 1), and by reactive deposition epitaxy on Si(0 0 1) substrates. The formation process is monitored by reflection high-energy electron diffraction. The morphology, size, and electrical properties of the nanoparticles are investigated by scanning electron microscopy, by electrically active scanning probe microscopy, and by confocal Raman spectroscopy. The results show that the shape, size, orientation, and density of the nanoobjects can be tuned by self-assembly, controlled by the lattice misfit between the substrates and iron silicides. The size distribution and shape of the grown nanoparticles depend on the substrate orientation, on the initial thickness of the evaporated iron, on the temperature and time of the annealing, and on the preparation method. The so-called Ostwald ripening phenomena, which state that the bigger objects develop at the expense of smaller ones, controls the density of the nanoparticles. Raman spectra show the bigger objects do not contain β-FeSi 2 phase. The different shape nanoparticles exhibit small, about 100 mV barrier compared to the surrounding silicon. The local leakage current of the samples measured by conductive AFM using a Pt coated Si tip is localized in a few nanometers size sites, and the sites which we assume are very small silicide nanoparticles or point defects.
Aluminium alloyed iron-silicide/silicon solar cells: A simple approach for low cost environmental-friendly photovoltaic technology.

Science.gov (United States)

Kumar Dalapati, Goutam; Masudy-Panah, Saeid; Kumar, Avishek; Cheh Tan, Cheng; Ru Tan, Hui; Chi, Dongzhi

2015-12-03

This work demonstrates the fabrication of silicide/silicon based solar cell towards the development of low cost and environmental friendly photovoltaic technology. A heterostructure solar cells using metallic alpha phase (α-phase) aluminum alloyed iron silicide (FeSi(Al)) on n-type silicon is fabricated with an efficiency of 0.8%. The fabricated device has an open circuit voltage and fill-factor of 240 mV and 60%, respectively. Performance of the device was improved by about 7 fold to 5.1% through the interface engineering. The α-phase FeSi(Al)/silicon solar cell devices have promising photovoltaic characteristic with an open circuit voltage, short-circuit current and a fill factor (FF) of 425 mV, 18.5 mA/cm(2), and 64%, respectively. The significant improvement of α-phase FeSi(Al)/n-Si solar cells is due to the formation p(+-)n homojunction through the formation of re-grown crystalline silicon layer (~5-10 nm) at the silicide/silicon interface. Thickness of the regrown silicon layer is crucial for the silicide/silicon based photovoltaic devices. Performance of the α-FeSi(Al)/n-Si solar cells significantly depends on the thickness of α-FeSi(Al) layer and process temperature during the device fabrication. This study will open up new opportunities for the Si based photovoltaic technology using a simple, sustainable, and los cost method.
Influence of iron and beryllium additions on heat resistance of silicide coatings on TsMB-30 molybdenum alloy

International Nuclear Information System (INIS)

Zajtseva, A.L.; Fedorchuk, N.M.; Lazarev, Eh.M.; Korotkov, N.A.

1985-01-01

Alloying of titanium modified silicide coatings on TsMB-30 molybdenum alloy with iron or beryllium is stated to improve their protective properties. Coatings with low content of alloying elements have the best protective properties. Service life of coatings is determined by the formed oxide film and phase transformations taking place in the coating
Nanoprecipitation in bearing steels

International Nuclear Information System (INIS)

Barrow, A.T.W.; Rivera-Diaz-del-Castillo, P.E.J.

2011-01-01

θ-phase is the main hardening species in bearing steels and appears in both martensitically and bainitically hardened microstructures. This work presents a survey of the microstrucural features accompanying nanoprecipitation in bearing steels. Nanoprecipitate structures formed in 1C-1.5Cr wt.% with additions of Cr, Mn, Mo, Si and Ni are studied. The work is combined with thermodynamic calculations and neural networks to predict the expected matrix composition, and whether this will transform martensitically or bainitically. Martensite tetragonality, composition and the amount of retained austenite are related to hardness and the type of nanoprecipitate structures in martensitic grades. The θ-phase volume fraction, the duration of the bainite to austenite transformation and the amount of retained austenite are related to hardness and a detailed quantitative description of the precipitate nanostructures. Such description includes compositional studies using energy-dispersive spectroscopy, which shows that nanoprecipitate formation takes place under paraequilibrium. Special attention is devoted to a novel two-step bainite tempering process which shows maximum hardness; we prove that this is the most effective process for incorporating solute into the precipitates, which are finer than those resulting from one-step banitic transformation processes.
Nanoprecipitation process: From encapsulation to drug delivery.

Science.gov (United States)

Martínez Rivas, Claudia Janeth; Tarhini, Mohamad; Badri, Waisudin; Miladi, Karim; Greige-Gerges, Hélène; Nazari, Qand Agha; Galindo Rodríguez, Sergio Arturo; Román, Rocío Álvarez; Fessi, Hatem; Elaissari, Abdelhamid

2017-10-30

Drugs encapsulation is a suitable strategy in order to cope with the limitations of conventional dosage forms such as unsuitable bioavailability, stability, taste, and odor. Nanoprecipitation technique has been used in the pharmaceutical and agricultural research as clean alternative for other drug carrier formulations. This technique is based on precipitation mechanism. Polymer precipitation occurs after the addition of a non-solvent to a polymer solution in four steps mechanism: supersaturation, nucleation, growth by condensation, and growth by coagulation that leads to the formation of polymer nanoparticles or aggregates. The scale-up of laboratory-based nanoprecipitation method shows a good reproducibility. In addition, flash nanoprecipitation is a good strategy for industrial scale production of nanoparticles. Nanoprecipitation is usually used for encapsulation of hydrophobic or hydrophilic compounds. Nanoprecipitation was also shown to be a good alternative for the encapsulation of natural compounds. As a whole, process and formulation related parameters in nanoprecipitation technique have critical effect on nanoparticles characteristics. Biodegradable or non-biodegradable polymers have been used for the preparation of nanoparticles intended to in vivo studies. Literature studies have demonstrated the biodistribution of the active loaded nanoparticles in different organs after administration via various routes. In general, in vitro drug release from nanoparticles prepared by nanoprecipitation includes two phases: a first phase of "burst release" which is followed by a second phase of prolonged release. Moreover, many encapsulated active molecules have been commercialized in the pharmaceutical market. Copyright © 2017 Elsevier B.V. All rights reserved.
Magnesium silicide production and silane synthesis on its basis

International Nuclear Information System (INIS)

Taurbaev, T.I.; Mukashev, F.A.; Manakov, S.M.; Francev, U.V.; Kalblanbekov, B.M.; Akhter, P.; Abbas, M.; Hussain, A.

2003-01-01

We had developed an alternative method of production of magnesium silicide with use of ferroalloys of silicon. Magnesium silicide is raw material for silane synthesis. The essence of the method consist of sintering FS -75 (ferrosilicium with 75 % of silicon and 25 % of iron, made by ferroalloy factories) with metal magnesium at temperature of 650 deg. C. The X-ray analysis has shown formation of magnesium silicide. That is further used for synthesis of silane. The output of silane is 60 % in respect of the contents of silicon. After removing the water vapors the mass-spectrometer analysis has estimated the purity of silane as 99.95 % with no detection of phosphine and diborane. (author)
Refractory silicides for integrated circuits

International Nuclear Information System (INIS)

Murarka, S.P.

1980-01-01

Transition metal silicides have, in the past, attracted attention because of their usefulness as high temperature materials and in integrated circuits as Schottky barrier and ohmic contacts. More recently, with the increasing silicon integrated circuits (SIC) packing density, the line widths get narrower and the sheet resistance contribution to the RC delay increases. The possibility of using low resistivity silicides, which can be formed directly on the polysilicon, makes these silicides highly attractive. The usefulness of a silicide metallization scheme for integrated circuits depends, not only on the desired low resistivity, but also on the ease with which the silicide can be formed and patterned and on the stability of the silicides throughout device processing and during actual device usage. In this paper, various properties and the formation techniques of the silicides have been reviewed. Correlations between the various properties and the metal or silicide electronic or crystallographic structure have been made to predict the more useful silicides for SIC applications. Special reference to the silicide resistivity, stress, and oxidizability during the formation and subsequent processing has been given. Various formation and etching techniques are discussed
Edge energies and shapes of nanoprecipitates.

Energy Technology Data Exchange (ETDEWEB)

Hamilton, John C.

2006-01-01

In this report we present a model to explain the size-dependent shapes of lead nano-precipitates in aluminum. Size-dependent shape transitions, frequently observed at nanolength scales, are commonly attributed to edge energy effects. This report resolves an ambiguity in the definition and calculation of edge energies and presents an atomistic calculation of edge energies for free clusters. We also present a theory for size-dependent shapes of Pb nanoprecipitates in Al, introducing the concept of ''magic-shapes'' defined as precipitate shapes having near zero elastic strains when inserted into similarly shaped voids in the Al matrix. An algorithm for constructing a complete set of magic-shapes is presented. The experimental observations are explained by elastic strain energies and interfacial energies; edge energies play a negligible role. We replicate the experimental observations by selecting precipitates having magic-shapes and interfacial energies less than a cutoff value.
Surface morphology of erbium silicide

International Nuclear Information System (INIS)

Lau, S.S.; Pai, C.S.; Wu, C.S.; Kuech, T.F.; Liu, B.X.

1982-01-01

The surface of rare-earth silicides (Er, Tb, etc.), formed by the reaction of thin-film metal layers with a silicon substrate, is typically dominated by deep penetrating, regularly shaped pits. These pits may have a detrimental effect on the electronic performance of low Schottky barrier height diodes utilizing such silicides on n-type Si. This study suggests that contamination at the metal-Si or silicide-Si interface is the primary cause of surface pitting. Surface pits may be reduced in density or eliminated entirely through either the use of Si substrate surfaces prepared under ultrahigh vacuum conditions prior to metal deposition and silicide formation or by means of ion irradiation techniques. Silicide layers formed by these techniques possess an almost planar morphology
The formation of magnetic silicide Fe3Si clusters during ion implantation

Science.gov (United States)

Balakirev, N.; Zhikharev, V.; Gumarov, G.

2014-05-01

A simple two-dimensional model of the formation of magnetic silicide Fe3Si clusters during high-dose Fe ion implantation into silicon has been proposed and the cluster growth process has been computer simulated. The model takes into account the interaction between the cluster magnetization and magnetic moments of Fe atoms random walking in the implanted layer. If the clusters are formed in the presence of the external magnetic field parallel to the implanted layer, the model predicts the elongation of the growing cluster in the field direction. It has been proposed that the cluster elongation results in the uniaxial magnetic anisotropy in the plane of the implanted layer, which is observed in iron silicide films ion-beam synthesized in the external magnetic field.
The formation of magnetic silicide Fe3Si clusters during ion implantation

International Nuclear Information System (INIS)

Balakirev, N.; Zhikharev, V.; Gumarov, G.

2014-01-01

A simple two-dimensional model of the formation of magnetic silicide Fe 3 Si clusters during high-dose Fe ion implantation into silicon has been proposed and the cluster growth process has been computer simulated. The model takes into account the interaction between the cluster magnetization and magnetic moments of Fe atoms random walking in the implanted layer. If the clusters are formed in the presence of the external magnetic field parallel to the implanted layer, the model predicts the elongation of the growing cluster in the field direction. It has been proposed that the cluster elongation results in the uniaxial magnetic anisotropy in the plane of the implanted layer, which is observed in iron silicide films ion-beam synthesized in the external magnetic field
The formation of magnetic silicide Fe{sub 3}Si clusters during ion implantation

Energy Technology Data Exchange (ETDEWEB)

Balakirev, N. [Kazan National Research Technological University, K.Marx st. 68, Kazan 420015 (Russian Federation); Zhikharev, V., E-mail: valzhik@mail.ru [Kazan National Research Technological University, K.Marx st. 68, Kazan 420015 (Russian Federation); Gumarov, G. [Zavoiskii Physico-Technical Institute of Russian Academy of Sciences, 10/7 Sibirskii trakt st., Kazan 420029 (Russian Federation)

2014-05-01

A simple two-dimensional model of the formation of magnetic silicide Fe{sub 3}Si clusters during high-dose Fe ion implantation into silicon has been proposed and the cluster growth process has been computer simulated. The model takes into account the interaction between the cluster magnetization and magnetic moments of Fe atoms random walking in the implanted layer. If the clusters are formed in the presence of the external magnetic field parallel to the implanted layer, the model predicts the elongation of the growing cluster in the field direction. It has been proposed that the cluster elongation results in the uniaxial magnetic anisotropy in the plane of the implanted layer, which is observed in iron silicide films ion-beam synthesized in the external magnetic field.
Nanoprecipitation of polymers in a bad solvent

NARCIS (Netherlands)

Lebouille, J.G.J.L.; Stepanyan, R.; Slot, J.J.M.; Cohen Stuart, M.A.; Tuinier, R.

2014-01-01

Nanoparticles (NPs) composed of polymers are of great interest since they can add a functionality in many applications, ranging from food and pharma to plastics and electronics. A key factor that determines the functionality of NPs is their size. Nanoprecipitation [1] is a commonly used technique to
Self-assembling process of flash nanoprecipitation in a multi-inlet vortex mixer to produce drug-loaded polymeric nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Shen Hao [University of Illinois at Chicago, Department of Chemical Engineering (United States); Hong, Seungpyo [University of Illinois at Chicago, Department of Biopharmaceutical Sciences (United States); Prud' homme, Robert K. [Princeton University, Department of Chemical Engineering (United States); Liu Ying, E-mail: liuying@uic.edu [University of Illinois at Chicago, Department of Chemical Engineering (United States)

2011-09-15

We present an experimental study of self-assembled polymeric nanoparticles in the process of flash nanoprecipitation using a multi-inlet vortex mixer (MIVM). {beta}-Carotene and polyethyleneimine (PEI) are used as a model drug and a macromolecule, respectively, and encapsulated in diblock copolymers. Flow patterns in the MIVM are microscopically visualized by mixing iron nitrate (Fe(NO{sub 3}){sub 3}) and potassium thiocyanate (KSCN) to precipitate Fe(SCN){sub x}{sup (3-x)+}. Effects of physical parameters, including Reynolds number, supersaturation rate, interaction force, and drug-loading rate, on size distribution of the nanoparticle suspensions are investigated. It is critical for the nanoprecipitation process to have a short mixing time, so that the solvent replacement starts homogeneously in the reactor. The properties of the nanoparticles depend on the competitive kinetics of polymer aggregation and organic solute nucleation and growth. We report the existence of a threshold Reynolds number over which nanoparticle sizes become independent of mixing. A similar value of the threshold Reynolds number is confirmed by independent measurements of particle size, flow-pattern visualization, and our previous numerical simulation along with experimental study of competitive reactions in the MIVM.
Near surface silicide formation after off-normal Fe-implantation of Si(001) surfaces

Energy Technology Data Exchange (ETDEWEB)

Khanbabaee, B., E-mail: khanbabaee@physik.uni-siegen.de; Pietsch, U. [Solid State Physics, University of Siegen, D-57068 Siegen (Germany); Lützenkirchen-Hecht, D. [Fachbereich C - Physik, Bergische Universität Wuppertal, D-42097 Wuppertal (Germany); Hübner, R.; Grenzer, J.; Facsko, S. [Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden (Germany)

2014-07-14

We report on formation of non-crystalline Fe-silicides of various stoichiometries below the amorphized surface of crystalline Si(001) after irradiation with 5 keV Fe{sup +} ions under off-normal incidence. We examined samples prepared with ion fluences of 0.1 × 10{sup 17} and 5 × 10{sup 17} ions cm{sup −2} exhibiting a flat and patterned surface morphology, respectively. Whereas the iron silicides are found across the whole surface of the flat sample, they are concentrated at the top of ridges at the rippled surface. A depth resolved analysis of the chemical states of Si and Fe atoms in the near surface region was performed by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy (XAS) using synchrotron radiation. The chemical shift and the line shape of the Si 2p core levels and valence bands were measured and associated with the formation of silicide bonds of different stoichiometric composition changing from an Fe-rich silicides (Fe{sub 3}Si) close to the surface into a Si-rich silicide (FeSi{sub 2}) towards the inner interface to the Si(001) substrate. This finding is supported by XAS analysis at the Fe K-edge which shows changes of the chemical environment and the near order atomic coordination of the Fe atoms in the region close to surface. Because a similar Fe depth profile has been found for samples co-sputtered with Fe during Kr{sup +} ion irradiation, our results suggest the importance of chemically bonded Fe in the surface region for the process of ripple formation.
Mechanism of co-nanoprecipitation of organic actives and block copolymers in a microfluidic environment

International Nuclear Information System (INIS)

Capretto, Lorenzo; Cheng Wei; Carugo, Dario; Katsamenis, Orestis L; Zhang Xunli; Hill, Martyn

2012-01-01

Microreactors have been shown to be a powerful tool for the production of nanoparticles (NPs); however, there is still a lack of understanding of the role that the microfluidic environment plays in directing the nanoprecipitation process. Here we investigate the mechanism of nanoprecipitation of block copolymer stabilized organic NPs using a microfluidic-based reactor in combination with computational fluid dynamics (CFD) modelling of the microfluidic implementation. The latter also accounts for the complex interplay between molecular and hydrodynamic phenomena during the nanoprecipitation process, in order to understand the hydrodynamics and its influence on the NP formation process. It is demonstrated that the competitive reactions result in the formation of two types of NPs, i.e., either with or without loading organic actives. The obtained results are interpreted by taking into consideration a new parameter representing the mismatching between the aggregations of the polymers and actives, which plays a decisive role in determining the size and polydispersity of the prepared hybrid NPs. These results expand the current understanding of the co-nanoprecipitation mechanism of active and block copolymer stabilizer, and on the role exerted by the microfluidic environment, giving information that could be translated to the emerging fields of microfluidic formation of NPs and nanomedicine. (paper)

Irradiation behavior of miniature experimental uranium silicide fuel plates

International Nuclear Information System (INIS)

Hofman, G.L.; Neimark, L.A.; Mattas, R.F.

1983-01-01

Uranium silicides, because of their relatively high uranium density, were selected as candidate dispersion fuels for the higher fuel densities required in the Reduced Enrichment Research and Test Reactor (RERTR) Program. Irradiation experience with this type of fuel, however, was limited to relatively modest fission densities in the bulk from, on the order of 7 x 10 20 cm -3 , far short of the approximately 20 x 10 20 cm -3 goal established for the RERTR program. The purpose of the irradiation experiments on silicide fuels on the ORR, therefore, was to investigate the intrinsic irradiation behavior of uranium silicide as a dispersion fuel. Of particular interest was the interaction between the silicide particles and the aluminum matrix, the swelling behavior of the silicide particles, and the maximum volume fraction of silicide particles that could be contained in the aluminum matrix
Protein-Based Nanoparticle Preparation via Nanoprecipitation Method

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Mohamad Tarhini

2018-03-01

Full Text Available Nanoparticles are nowadays largely investigated in the field of drug delivery. Among nanoparticles, protein-based particles are of paramount importance since they are natural, biodegradable, biocompatible, and nontoxic. There are several methods to prepare proteins containing nanoparticles, but only a few studies have been dedicated to the preparation of protein- based nanoparticles. Then, the aim of this work was to report on the preparation of bovine serum albumin (BSA-based nanoparticles using a well-defined nanoprecipitation process. Special attention has been dedicated to a systematic study in order to understand separately the effect of each operating parameter of the method (such as protein concentration, solvent/non-solvent volume ratio, non-solvent injection rate, ionic strength of the buffer solution, pH, and cross-linking on the colloidal properties of the obtained nanoparticles. In addition, the mixing processes (batch or drop-wise were also investigated. Using a well-defined formulation, submicron protein-based nanoparticles have been obtained. All prepared particles have been characterized in terms of size, size distribution, morphology, and electrokinetic properties. In addition, the stability of nanoparticles was investigated using Ultraviolet (UV scan and electrophoresis, and the optimal conditions for preparing BSA nanoparticles by the nanoprecipitation method were concluded.
Recent Advances in Nb-silicide in-situ composites

International Nuclear Information System (INIS)

Bewlay, B.P.; Jackson, M.R.; Subramanian, P.R.; Briant, C.L.

2001-01-01

In-situ composites based on Nb silicides have great potential for future high-temperature applications. These Nb-silicide composites combine a ductile Nb-based matrix with high-strength silicides. With the appropriate combination of alloying elements, such as Ti, Hf, Cr, AI, it is possible to achieve a promising balance of fracture toughness, high-temperature creep performance, and oxidation resistance. This paper will describe the effect of volume fraction of silicide on microstructure, high-temperature creep performance, and oxidation resistance. The ratio of Nb:(W+Ti) is critical in determining both creep rate and oxidation performance. If this ratio goes below ∼1.5, the creep rate increases substantially. In more complex silicide-based systems, other intermetallics, such as laves phases and a boron-rich T-2 phase, are added for oxidation resistance. To understand the role of each phase on the creep resistance and oxidation performance of these composites, we determined the creep and oxidation behavior of the individual phases and composites at temperatures up to 1200 o C. These data allow quantification of the load-bearing capability of the individual phases in the Nb-silicide based in-situ composites. (author)
Thermodynamic Properties of Alloys of Iron and Silicon

International Nuclear Information System (INIS)

Vecher, R.A.; Gejderih, V.A.; Gerasimov, Ja.I.

1966-01-01

The Fe-Si phase diagram is complex. At 1000°K there are FeSi 2 (β) and FeSi phases and solid solutions of silicon in α and α' iron. EMF measurements were made on the electrochemical cells: Fe|Fe 2+ , KI + Nal|Fe-Si at 600-800°C molten The alloys were prepared from particularly pure components by powder metallurgy and protracted annealing. Studies were made of ten alloys with silicon content between 85 and 4% in all the phase fields in the diagram section at 1000°K. We calculated the integral thermodynamic quantities ΔG, ΔH and ΔS for the formation of the silicides FeSi 2 (β), FeSi and Fe 3 Si at the mean temperature for the experimental range (1000°K), and also (using the thermal capacity of the silicides, the iron and the silicon) at 298, 1188 and 1798°K. The heats of formation of the silicides mentioned at 298°K (kcal/mole) are -19.4, -17.6 and -22.4 respectively. The data existing in the literature enable us to calculate the heat of formation of FeSi 2.33 (α-leboite) at 298°K and this is found to be -14.4 kcal/mole. The heats calculated by us are 1.5-3 kcal higher than the experimental values of Corber and Olsen. The heats of mixing calculated by us for liquid alloys agree well with data in the literature. The data obtained can be regarded as due to the change in the character of the bond in silicides from metallic to covalent when the silicon content is increased. From the data for alloy solutions of silicon in a-iron, the iron activities were calculated. It was found that the α ⇌ α' transformation observed is a real phase transformation. The two-phase range is wider than shown in the phase diagram (from data in the literature). Conversion of the iron activities in solid solution to liquid solution gives good agreement with the data of Chipman. (author) [fr
TiSi2 integrity within a doped silicide process step

International Nuclear Information System (INIS)

Crean, G.M.; Cole, P.D.; Stoemenos, J.

1993-01-01

Degradation of arsenic implanted titanium silicide (TiSi 2 ) thin films as a result of thermal processing for shallow junction formation is investigated. Significant arsenic diffusion from the silicide overlayer into the silicon substrate has been detected by Rutherford Backscattering Spectrometry at drive-in temperatures > 1,050 C. Cross-sectional transmission electron micrographs have shown the silicide film become increasingly non-uniform as the thermal budget increases, ultimately leading to discontinuities forming in the silicide film. This observed degradation of the titanium silicide film is also supported by sheet resistance measurements which show the film to degrade significantly above a threshold thermal budget
Subsurface contributions in epitaxial rare-earth silicides

Energy Technology Data Exchange (ETDEWEB)

Luebben, Olaf; Shvets, Igor V. [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), School of Physics, Trinity College, Dublin (Ireland); Cerda, Jorge I. [Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Cantoblanco, Madrid (Spain); Chaika, Alexander N. [Institute of Solid State Physics, RAS, Chernogolovka (Russian Federation)

2015-07-01

Metallic thin films of heavy rare-earth silicides epitaxially grown on Si(111) substrates have been widely studied in recent years because of their appealing properties: unusually low values of the Schottky barrier height, an abrupt interface, and a small lattice mismatch. Previous studies also showed that these silicides present very similar atomic and electronic structures. Here, we examine one of these silicides (Gd{sub 3}Si{sub 5}) using scanning tunneling microscopy (STM) image simulations that go beyond the Tersoff-Hamann approach. These simulations strongly indicate an unusual STM depth sensitivity for this system.
Morphology of Si/tungsten-silicides/Si interlayers

International Nuclear Information System (INIS)

Theodore, N.; Secco d'Aragona, F.; Blackstone, S.

1992-01-01

Tungsten and tungsten-silicides are of interest for semiconductor technology because of their refractory nature, low electrical-resistivity and high electromigration-resistance. This paper presents the first formation of buried tungsten-silicide layers in silicon, by proximity adhesion. The interlayers, created by a combination of chemical vapor-deposition (CVD) and proximity-adhesion were studied using transmission electron-microscopy (TEM). The behavior of the layers in the presence and absence of an adjacent silicon-dioxide interlayer was also investigated. Buried silicide layers were successfully formed with or without the adjacent silicon-dioxide. The silicide formed continuous layers with single grains encompassing the width of the interlayer. Individual grains were globular, with cusps at grain boundaries. This caused interlayer-thicknesses to be non-uniform, with lower thickness values being present at the cusps. Occasional voids were observed at grain-boundary cusps. The voids were smaller and less frequent in the presence of an adjacent oxide-layer, due to flow of the oxide during proximity adhesion. Electron-diffraction revealed a predominance of tungsten-disilicide in the interlayers, with some free tungsten being present. Stresses in the silicide layers caused occasional glide dislocations to propagate into the silicon substrate beneath the interlayers. The dislocations propagate only ∼100 nm into the substrate and therefore should not be detrimental to use of the buried layers. Occasional precipitates were observed at the end of glide-loops. These possibly arise due to excess tungsten from the interlayer diffusion down the glide dislocation to finally precipitate out as tungsten-silicide
Analyses on Silicide Coating for LOCA Resistant Cladding

Energy Technology Data Exchange (ETDEWEB)

Sweidan, Faris B.; Lee, You Ho; Ryu, Ho Jin [KAIST, Daejeon (Korea, Republic of)

2015-10-15

A particular focus of accident-tolerant fuel has been cladding due to the rapid high-temperature oxidation of zirconium-based cladding with the evolution of H2 when steam is a reactant. Some key features of the coated cladding include high-temperature resistance to oxidation, lower processing temperatures, and a high melting point of the coating. Zirconium alloys exhibit a reasonably high melting temperature, so a coating for the cladding is appealing if the coating increases the high-temperature resistance to oxidation. In this case, the cladding is protected from complete oxidation. The cladding coating involves the application of zirconium silicide onto Zr-based cladding. Zirconium silicide coating is expected to produce a glassy layer that becomes more protective at elevated temperature. For this reason, silicide coatings on cladding offer the potential for improved reliability at normal operating temperatures and at the higher transient temperatures encountered during accidents. Although ceramic coatings are brittle and may have weak points to be used as coating materials, several ceramic coatings were successful and showed adherent behavior and high resistance to oxidation. In this study, the oxidation behavior of zirconium silicide and its oxidation kinetics are analyzed. Zirconium silicide is a new suggested material to be used as coatings on existing Zr-based cladding alloys, the aim of this study is to evaluate if zirconium silicide is applicable to be used, so they can be more rapidly developed using existing cladding technology with some modifications. These silicide coatings are an attractive alternative to the use of coatings on zirconium claddings or to the lengthy development of monolithic ceramic or ceramic composite claddings and coatings.
Analyses on Silicide Coating for LOCA Resistant Cladding

International Nuclear Information System (INIS)

Sweidan, Faris B.; Lee, You Ho; Ryu, Ho Jin

2015-01-01

A particular focus of accident-tolerant fuel has been cladding due to the rapid high-temperature oxidation of zirconium-based cladding with the evolution of H2 when steam is a reactant. Some key features of the coated cladding include high-temperature resistance to oxidation, lower processing temperatures, and a high melting point of the coating. Zirconium alloys exhibit a reasonably high melting temperature, so a coating for the cladding is appealing if the coating increases the high-temperature resistance to oxidation. In this case, the cladding is protected from complete oxidation. The cladding coating involves the application of zirconium silicide onto Zr-based cladding. Zirconium silicide coating is expected to produce a glassy layer that becomes more protective at elevated temperature. For this reason, silicide coatings on cladding offer the potential for improved reliability at normal operating temperatures and at the higher transient temperatures encountered during accidents. Although ceramic coatings are brittle and may have weak points to be used as coating materials, several ceramic coatings were successful and showed adherent behavior and high resistance to oxidation. In this study, the oxidation behavior of zirconium silicide and its oxidation kinetics are analyzed. Zirconium silicide is a new suggested material to be used as coatings on existing Zr-based cladding alloys, the aim of this study is to evaluate if zirconium silicide is applicable to be used, so they can be more rapidly developed using existing cladding technology with some modifications. These silicide coatings are an attractive alternative to the use of coatings on zirconium claddings or to the lengthy development of monolithic ceramic or ceramic composite claddings and coatings
Production of Mo-99 using low-enriched uranium silicide

International Nuclear Information System (INIS)

Hutter, J.C.; Srinivasan, B.; Vicek, M.; Vandegrift, G.F.

1994-01-01

Over the last several years, uranium silicide fuels have been under development as low-enriched uranium (LEU) targets for Mo-99. The use of LEU silicide is aimed at replacing the UAl x alloy in the highly-enriched uranium dissolution process. A process to recover Mo-99 from low-enriched uranium silicide is being developed at Argonne National Laboratory. The uranium silicide is dissolved in alkaline hydrogen peroxide. Experiments performed to determine the optimum dissolution procedure are discussed, and the results of dissolving a portion of a high-burnup (>40%) U 3 Si 2 miniplate are presented. Future work related to Mo-99 separation and waste disposal are also discussed
Room temperature ferromagnetic gadolinium silicide nanoparticles

Science.gov (United States)

Hadimani, Magundappa Ravi L.; Gupta, Shalabh; Harstad, Shane; Pecharsky, Vitalij; Jiles, David C.

2018-03-06

A particle usable as T1 and T2 contrast agents is provided. The particle is a gadolinium silicide (Gd5Si4) particle that is ferromagnetic at temperatures up to 290 K and is less than 2 .mu.m in diameter. An MRI contrast agent that includes a plurality of gadolinium silicide (Gd.sub.5Si.sub.4) particles that are less than 1 .mu.m in diameter is also provided. A method for creating gadolinium silicide (Gd5Si4) particles is also provided. The method includes the steps of providing a Gd5Si4 bulk alloy; grinding the Gd5Si4 bulk alloy into a powder; and milling the Gd5Si4 bulk alloy powder for a time of approximately 20 minutes or less.
Synthesis and characterization of β-phase iron silicide nano-particles by chemical reduction

International Nuclear Information System (INIS)

Sen, Sabyasachi; Gogurla, Narendar; Banerji, Pallab; Guha, Prasanta K.; Pramanik, Panchanan

2015-01-01

Graphical abstract: - Highlights: • β-FeSi 2 nano-particle was synthesized by reducing with Mg and by diluting with MgO. • XRD profile shows the iron di-silicide phase to be semiconducting β-FeSi 2 . • HRTEM and FESEM images indicate the β-FeSi 2 average particle size to be 60–70 nm. • Absorption, reflectance and PL spectroscopy show band gap to be direct 0.87 eV. • Nano-β-FeSi 2 is p-type with hole density of 4.38 × 10 18 cm −3 and mobility 8.9 cm 2 /V s. - Abstract: Nano-particles of β-FeSi 2 have been synthesized by chemical reduction of a glassy phase of [Fe 2 O 3 , 4SiO 2 ] by Mg-metal where MgO is used as diluent to prevent the agglomeration of nano crystallites into micro-particles and also act as a negative catalyst for the formation of other phases. The sample is characterized by XRD, FESEM, HRTEM, EDX, ultra-violet-visible-infrared and PL spectroscopy and electronic properties have been investigated by Hall measurement. XRD profile shows that the synthesized powder consists of purely β-FeSi 2 semiconducting phase. The average crystallite size of β-FeSi 2 is determined to be around 65.4 nm from XRD peaks as well as from FESEM also. The optical absorption and PL spectroscopy shows that synthesized β-FeSi 2 phase is a direct band gap semiconductor with a value of 0.87 eV. Hall measurements show that β-FeSi 2 nano-particles is p-type with hole concentration of 4.38 × 10 18 cm −3 and average hole mobility of 8.9 cm 2 /V s at 300 K
Precipitated iron. A limit on gettering efficacy in multicrystalline silicon

Energy Technology Data Exchange (ETDEWEB)

Fenning, D.P.; Hofstetter, J.; Bertoni, M.I.; Buonassisi, T. [Massachusetts Institute of Technology MIT, Cambridge, Massachusetts 02139 (United States); Coletti, G. [ECN Solar Energy, Westerduinweg 3, NL-1755 LE Petten (Netherlands); Lai, B. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Del Canizo, C. [Instituto de Energia Solar, Universidad Politecnica de Madrid, 28040 Madrid (Spain)

2013-01-31

A phosphorus diffusion gettering model is used to examine the efficacy of a standard gettering process on interstitial and precipitated iron in multicrystalline silicon. The model predicts a large concentration of precipitated iron remaining after standard gettering for most as-grown iron distributions. Although changes in the precipitated iron distribution are predicted to be small, the simulated post-processing interstitial iron concentration is predicted to depend strongly on the as-grown distribution of precipitates, indicating that precipitates must be considered as internal sources of contamination during processing. To inform and validate the model, the iron distributions before and after a standard phosphorus diffusion step are studied in samples from the bottom, middle, and top of an intentionally Fe-contaminated laboratory ingot. A census of iron-silicide precipitates taken by synchrotron-based X-ray fluorescence microscopy confirms the presence of a high density of iron-silicide precipitates both before and after phosphorus diffusion. A comparable precipitated iron distribution was measured in a sister wafer after hydrogenation during a firing step. The similar distributions of precipitated iron seen after each step in the solar cell process confirm that the effect of standard gettering on precipitated iron is strongly limited as predicted by simulation. Good agreement between the experimental and simulated data supports the hypothesis that gettering kinetics is governed by not only the total iron concentration but also by the distribution of precipitated iron. Finally, future directions based on the modeling are suggested for the improvement of effective minority carrier lifetime in multicrystalline silicon solar cells.
Palladium silicide - a new contact for semiconductor radiation detectors

International Nuclear Information System (INIS)

Totterdell, D.H.J.

1981-11-01

Silicide layers can be used as low resistance contacts in semiconductor devices. The formation of a metal rich palladium silicide Pd 2 Si is discussed. A palladium film 100A thick is deposited at 300 0 C and the resulting silicide layer used as an ohmic contact in an n + p silicon detector. This rugged contact has electrical characteristics comparable with existing evaporated gold contacts and enables the use of more reproducible bonding techniques. (author)
Reduction of chalcogen oxyanions and generation of nanoprecipitates by the photosynthetic bacterium Rhodobacter capsulatus

Energy Technology Data Exchange (ETDEWEB)

Borghese, Roberto, E-mail: roberto.borghese@unibo.it [Department of Pharmacy and Biotechnology, University of Bologna (Italy); Baccolini, Chiara; Francia, Francesco [Department of Pharmacy and Biotechnology, University of Bologna (Italy); Sabatino, Piera [Department of Chemistry G. Ciamician, University of Bologna (Italy); Turner, Raymond J. [Department of Biological Sciences, University of Calgary, Calgary, Alberta (Canada); Zannoni, Davide, E-mail: davide.zannoni@unibo.it [Department of Pharmacy and Biotechnology, University of Bologna (Italy)

2014-03-01

Graphical abstract: - Highlights: • R. capsulatus cells produce extracellular chalcogens nanoprecipitates when lawsone is present. • Lawsone acts as a redox mediator from reducing equivalents to tellurite and selenite. • Nanoprecipitates production depends on carbon source and requires metabolically active cells. • Te{sup 0} and Se{sup 0} nanoprecipitates are identified by X-ray diffraction (XRD) spectroscopy. - Abstract: The facultative photosynthetic bacterium Rhodobacter capsulatus is characterized in its interaction with the toxic oxyanions tellurite (Te{sup IV}) and selenite (Se{sup IV}) by a highly variable level of resistance that is dependent on the growth mode making this bacterium an ideal organism for the study of the microbial interaction with chalcogens. As we have reported in the past, while the oxyanion tellurite is taken up by R. capsulatus cells via acetate permease and it is reduced to Te{sup 0} in the cytoplasm in the form of splinter-like black intracellular deposits no clear mechanism was described for Se{sup 0} precipitation. Here, we present the first report on the biotransformation of tellurium and selenium oxyanions into extracellular Te{sup 0} and Se{sup 0}nanoprecipitates (NPs) by anaerobic photosynthetically growing cultures of R. capsulatus as a function of exogenously added redox-mediator lawsone, i.e. 2-hydroxy-1,4-naphthoquinone. The NPs formation was dependent on the carbon source used for the bacterial growth and the rate of chalcogen reduction was constant at different lawsone concentrations, in line with a catalytic role for the redox mediator. X-ray diffraction (XRD) analysis demonstrated the Te{sup 0} and Se{sup 0} nature of the nanoparticles.
A study of CoSix silicide formed by recoil implantation

International Nuclear Information System (INIS)

Kwok, H.L.

1989-01-01

This work investigated the formation of CoSi x silicides on n-Si by recoil implantation through a thin cobalt layer using an inert gas ion beam. The results suggest the formation of a very shallow (35 to 45 nm) silicide surface layer under the specific conditions of preparation. The surface layer resistivity was comparable to values reported for Co 2 Si and CoSi, although below the surface, the resistivity decreased. This appeared to suggest a change-over from cobalt-rich silicides near the surface to a more conducting silicide (CoSi 2 ) at the interface. (author)
Pb nanoprecipitates in Al: Magic-shape effects due to elastic strain

DEFF Research Database (Denmark)

Hamilton, J.C.; Leoard, F.; Johnson, Erik

2007-01-01

We present a theory for size-dependent shapes of Pb nanoprecipitates in Al, introducing the concept of "magic shapes," i.e., shapes having near-zero homogeneous elastic strains. Our quantitative atomistic calculations of edge energies show their effect on precipitate shape to be negligible, thus...
Analysis of reactivity accidents of the RSG-GAS core with silicide fuel

International Nuclear Information System (INIS)

Tukiran

2002-01-01

The fuels of RSG-GAS reactor is changed from uranium oxide to uranium silicide. For time being, the fuel of RSG-GAS core are mixed up between oxide and silicide fuels with 250 gr of loading and 2.96 g U/cm 3 of density, respectively. While, silicide fuel with 300 gr of loading is still under research. The advantages of silicide fuels are can be used in high density, so that, it can be stayed longer in the core at higher burn-up, therefore, the length of cycle is longer. The silicide fuel in RSG-GAS core is used in step-wise by using mixed up core. Firstly, it is used silicide fuel with 250 gr of loading and then, silicide fuel with 300 gr of loading (3.55 g U/cm 3 of density). In every step-wise of fuel loading must be analysed its safety margin. In this occasion, it is analysed the reactivity accident of RSG-GAS core with 300 gr of silicide fuel loading. The calculation was done by using POKDYN code which available at P2TRR. The calculation was done by reactivity insertion at start up and power rangers. From all cases which were have been done, the results of analysis showed that there is no anomaly and safety margin break at RSG-GAS core with 300 gr silicide fuel loading
Neutronic design of the RSG-GAS silicide core

Energy Technology Data Exchange (ETDEWEB)

Sembiring, T.M.; Kuntoro, I.; Hastowo, H. [Center for Development of Research Reactor Technology National Nuclear Energy Agency BATAN, PUSPIPTEK Serpong Tangerang, 15310 (Indonesia)

2002-07-01

The objective of core conversion program of the RSG-GAS multipurpose reactor is to convert the fuel from oxide, U{sub 3}O{sub 8}-Al to silicide, U{sub 3}Si{sub 2}-Al. The aim of the program is to gain longer operation cycle by having, which is technically possible for silicide fuel, a higher density. Upon constraints of the existing reactor system and utilization, an optimal fuel density in amount of 3.55 g U/cc was found. This paper describes the neutronic parameter design of the silicide equilibrium core and the design of its transition cores as well. From reactivity control point of view, a modification of control rod system is also discussed. All calculations are carried out by means of diffusion codes, Batan-EQUIL-2D, Batan-2DIFF and -3DIFF. The silicide core shows that longer operation cycle of 32 full power days can be achieved without decreasing the safety criteria and utilization capabilities. (author)
Room temperature ferromagnetic gadolinium silicide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Hadimani, Magundappa Ravi L.; Gupta, Shalabh; Harstad, Shane; Pecharsky, Vitalij; Jiles, David C.

2018-03-06

A particle usable as T₁ and T₂ contrast agents is provided. The particle is a gadolinium silicide (Gd₅Si₄) particle that is ferromagnetic at temperatures up to 290 K and is less than 2 .mu.m in diameter. An MRI contrast agent that includes a plurality of gadolinium silicide (Gd.sub.5Si.sub.4) particles that are less than 1 .mu.m in diameter is also provided. A method for creating gadolinium silicide (Gd₅Si₄) particles is also provided. The method includes the steps of providing a Gd₅Si₄ bulk alloy; grinding the Gd₅Si₄ bulk alloy into a powder; and milling the Gd₅Si₄ bulk alloy powder for a time of approximately 20 minutes or less.

Irradiation behavior of experimental miniature uranium silicide fuel plates

International Nuclear Information System (INIS)

Hofman, Gerard L.; Neimark, L.A.; Mattas, R.F.

1983-01-01

Uranium silicides, because of their relatively high uranium density, were selected as candidate dispersion fuels for the higher fuel densities required in the Reduced Enrichment Research and Test Reactor (RERTR) Program. Irradiation experience with this type of fuel, however, was limited to relatively modest fission densities in the bulk form, on the order of 7 x 10 20 cm -3 , far short of he approximately 20 x 10 20 cm -3 goal established for the RERTR Program. The purpose of the irradiation experiments on silicide fuels in the ORR, therefore, was to investigate the intrinsic irradiation behavior of uranium silicide as a dispersion fuel. Of particular interest was the interaction between the silicide particles and the aluminum matrix, the swelling behavior of the silicide particles, and the maximum volume fraction of silicide particles that could be contained in the aluminum matrix. The first group of experimental 'mini' fuel plates have recently reached the program's goal burnup and are in various stages of examination. Although the results to date indicate some limitations, it appears that within the range of parameters examined thus far the uranium silicide dispersion holds promise for satisfying most of the needs of the RERTR Program. The twelve experimental silicide dispersion fuel plates that were irradiated to approximately their goal exposure show the 30-vol % U 3 Si-Al plates to be in a stage of relatively rapid fission-gas-driven swelling at a fission density of 2 x 10 20 cm -3 . This fuel swelling will likely result in unacceptably large plate-thickness increases. The U 3 Si plates appear to be superior in this respect; however, they, too, are starting to move into the rapid fuel-swelling stage. Analysis of the currently available post irradiation data indicates that a 40-vol % dispersed fuel may offer an acceptable margin to the onset of unstable thickness changes at exposures of 2 x 10 21 fission/cm 3 . The interdiffusion between fuel and matrix
Determination of accurate metal silicide layer thickness by RBS

International Nuclear Information System (INIS)

Kirchhoff, J.F.; Baumann, S.M.; Evans, C.; Ward, I.; Coveney, P.

1995-01-01

Rutherford Backscattering Spectrometry (RBS) is a proven useful analytical tool for determining compositional information of a wide variety of materials. One of the most widely utilized applications of RBS is the study of the composition of metal silicides (MSi x ), also referred to as polycides. A key quantity obtained from an analysis of a metal silicide is the ratio of silicon to metal (Si/M). Although compositional information is very reliable in these applications, determination of metal silicide layer thickness by RBS techniques can differ from true layer thicknesses by more than 40%. The cause of these differences lies in how the densities utilized in the RBS analysis are calculated. The standard RBS analysis software packages calculate layer densities by assuming each element's bulk densities weighted by the fractional atomic presence. This calculation causes large thickness discrepancies in metal silicide thicknesses because most films form into crystal structures with distinct densities. Assuming a constant layer density for a full spectrum of Si/M values for metal silicide samples improves layer thickness determination but ignores the underlying physics of the films. We will present results of RBS determination of the thickness various metal silicide films with a range of Si/M values using a physically accurate model for the calculation of layer densities. The thicknesses are compared to scanning electron microscopy (SEM) cross-section micrographs. We have also developed supporting software that incorporates these calculations into routine analyses. (orig.)
Si-Ge Nano-Structured with Tungsten Silicide Inclusions

Science.gov (United States)

Mackey, Jon; Sehirlioglu, Alp; Dynys, Fred

2014-01-01

Traditional silicon germanium high temperature thermoelectrics have potential for improvements in figure of merit via nano-structuring with a silicide phase. A second phase of nano-sized silicides can theoretically reduce the lattice component of thermal conductivity without significantly reducing the electrical conductivity. However, experimentally achieving such improvements in line with the theory is complicated by factors such as control of silicide size during sintering, dopant segregation, matrix homogeneity, and sintering kinetics. Samples are prepared using powder metallurgy techniques; including mechanochemical alloying via ball milling and spark plasma sintering for densification. In addition to microstructural development, thermal stability of thermoelectric transport properties are reported, as well as couple and device level characterization.
Synthesis and design of silicide intermetallic materials

Energy Technology Data Exchange (ETDEWEB)

Petrovic, J.J.; Castro, R.G.; Butt, D.P. [Los Alamos National Lab., NM (United States)] [and others

1997-04-01

The overall objective of this program is to develop structural silicide-based materials with optimum combinations of elevated temperature strength/creep resistance, low temperature fracture toughness, and high temperature oxidation and corrosion resistance for applications of importance to the U.S. processing industry. A further objective is to develop silicide-based prototype industrial components. The ultimate aim of the program is to work with industry to transfer the structural silicide materials technology to the private sector in order to promote international competitiveness in the area of advanced high temperature materials and important applications in major energy-intensive U.S. processing industries. The program presently has a number of developing industrial connections, including a CRADA with Schuller International Inc. targeted at the area of MoSi{sub 2}-based high temperature materials and components for fiberglass melting and processing applications. The authors are also developing an interaction with the Institute of Gas Technology (IGT) to develop silicides for high temperature radiant gas burner applications, for the glass and other industries. Current experimental emphasis is on the development and characterization of MoSi{sub 2}-Si{sub 3}N{sub 4} and MoSi{sub 2}-SiC composites, the plasma spraying of MoSi{sub 2}-based materials, and the joining of MoSi{sub 2} materials to metals.
Thermal stability of Ni-Pt-Ta alloy silicides on epi-Si1-xCx

International Nuclear Information System (INIS)

Yoo, Jung-Ho; Chang, Hyun-Jin; Min, Byoung-Gi; Ko, Dae-Hong; Cho, Mann-Ho; Sohn, Hyunchul; Lee, Tae-Wan

2008-01-01

We investigated the silicide formation in Ni/epi-Si 1-x C x systems. Ni-Pt and Ni-Pt-Ta films were deposited on epi-Si 1-x C x /Si substrates by DC magnetron sputtering and processed at various temperatures. The sheet resistance of the silicide from the Ni alloy/epi-Si 1-x C x systems was maintained at low values compared to that from Ni/Si systems. By TEM and EDS analyses, we confirmed the presence of a Pt alloy layer at the top of the Ni-silicide layer. The stability of the silicide layer in the Ni alloy/epi-Si 1-x C x system is explained by not only the Pt rich layer on the top of the Ni-silicide layer, but also by the presence of a small amount of Pt in the Ni-silicide layer or at the grain boundaries. And both the thermal stability and the morphology of silicide were greatly improved by the addition of Ta in Ni-Pt films
Reprocessing of LEU silicide fuel at Dounreay

International Nuclear Information System (INIS)

Cartwright, P.

1996-01-01

UKAEA have recently reprocessed two LEU silicide fuel elements in their MTR fuel reprocessing plant at Dounreay. The reprocessing was undertaken to demonstrate UKAEA's commitment to the world-wide research reactor communities future needs. Reprocessing of LEU silicide fuel is seen as a waste treatment process, resulting in the production of a liquid feed suitable for conditioning in a stable form of disposal. The uranium product from the reprocessing can be used as a blending feed with the HEU to produce LEU for use in the MTR cycle. (author)
Mechanoactivation of chromium silicide formation in the SiC-Cr-Si system

Directory of Open Access Journals (Sweden)

Vlasova M.

2002-01-01

Full Text Available The processes of simultaneous grinding of the components of a SiC-Cr-Si mixture and further temperature treatment in the temperature range 1073-1793 K were studied by X-ray phase analysis, IR spectroscopy, electron microscopy, and X-ray microanalysis. It was established that, during grinding of the mixture, chromium silicides form. A temperature treatment completes the process. Silicide formation proceeds within the framework of the diffusion of silicon into chromium. In the presence of SiO2 in the mixture, silicide formation occurs also as a result of the reduction of silica by silicon and silicon carbide. The sintering of synthesized composite SiC-chromium silicides powders at a high temperature under a high pressure (T = 2073 K, P = 5 GPa is accompanied by the destruction of cc-SiC particles, the cc/3 transition in silicon carbide and deformation distortions of the lattices of chromium silicides.
Thermoelectric characteristics of Pt-silicide/silicon multi-layer structured p-type silicon

International Nuclear Information System (INIS)

Choi, Wonchul; Jun, Dongseok; Kim, Soojung; Shin, Mincheol; Jang, Moongyu

2015-01-01

Electric and thermoelectric properties of silicide/silicon multi-layer structured devices were investigated with the variation of silicide/silicon heterojunction numbers from 3 to 12 layers. For the fabrication of silicide/silicon multi-layered structure, platinum and silicon layers are repeatedly sputtered on the (100) silicon bulk substrate and rapid thermal annealing is carried out for the silicidation. The manufactured devices show ohmic current–voltage (I–V) characteristics. The Seebeck coefficient of bulk Si is evaluated as 195.8 ± 15.3 μV/K at 300 K, whereas the 12 layered silicide/silicon multi-layer structured device is evaluated as 201.8 ± 9.1 μV/K. As the temperature increases to 400 K, the Seebeck coefficient increases to 237.2 ± 4.7 μV/K and 277.0 ± 1.1 μV/K for bulk and 12 layered devices, respectively. The increase of Seebeck coefficient in multi-layered structure is mainly attributed to the electron filtering effect due to the Schottky barrier at Pt-silicide/silicon interface. At 400 K, the thermal conductivity is reduced by about half of magnitude compared to bulk in multi-layered device which shows the efficient suppression of phonon propagation by using Pt-silicide/silicon hetero-junctions. - Highlights: • Silicide/silicon multi-layer structured is proposed for thermoelectric devices. • Electric and thermoelectric properties with the number of layer are investigated. • An increase of Seebeck coefficient is mainly attributed the Schottky barrier. • Phonon propagation is suppressed with the existence of Schottky barrier. • Thermal conductivity is reduced due to the suppression of phonon propagation
Formation of iron disilicide on amorphous silicon

Science.gov (United States)

Erlesand, U.; Östling, M.; Bodén, K.

1991-11-01

Thin films of iron disilicide, β-FeSi 2 were formed on both amorphous silicon and on crystalline silicon. The β-phase is reported to be semiconducting with a direct band-gap of about 0.85-0.89 eV. This phase is known to form via a nucleation-controlled growth process on crystalline silicon and as a consequence a rather rough silicon/silicide interface is usually formed. In order to improve the interface a bilayer structure of amorphous silicon and iron was sequentially deposited on Czochralski silicon in an e-gun evaporation system. Secondary ion mass spectrometry profiling (SIMS) and scanning electron micrographs revealed an improvement of the interface sharpness. Rutherford backscattering spectrometry (RBS) and X-ray diffractiometry showed β-FeSi 2 formation already at 525°C. It was also observed that the silicide growth was diffusion-controlled, similar to what has been reported for example in the formation of NiSi 2 for the reaction of nickel on amorphous silicon. The kinetics of the FeSi 2 formation in the temperature range 525-625°C was studied by RBS and the activation energy was found to be 1.5 ± 0.1 eV.
Transport Measurements and Synchrotron-Based X-Ray Absorption Spectroscopy of Iron Silicon Germanide Grown by Molecular Beam Epitaxy

Science.gov (United States)

Elmarhoumi, Nader; Cottier, Ryan; Merchan, Greg; Roy, Amitava; Lohn, Chris; Geisler, Heike; Ventrice, Carl, Jr.; Golding, Terry

2009-03-01

Some of the iron-based metal silicide and germanide phases have been predicted to be direct band gap semiconductors. Therefore, they show promise for use as optoelectronic materials. We have used synchrotron-based x-ray absorption spectroscopy to study the structure of iron silicon germanide films grown by molecular beam epitaxy. A series of Fe(Si1-xGex)2 thin films (2000 -- 8000å) with a nominal Ge concentration of up to x = 0.04 have been grown. X-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) measurements have been performed on the films. The nearest neighbor co-ordination corresponding to the β-FeSi2 phase of iron silicide provides the best fit with the EXAFS data. Temperature dependent (20 coefficient was calculated. Results suggest semiconducting behavior of the films which is consistent with the EXAFS results.
Gas cluster ion beam assisted NiPt germano-silicide formation on SiGe

Energy Technology Data Exchange (ETDEWEB)

Ozcan, Ahmet S., E-mail: asozcan@us.ibm.com [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States); Lavoie, Christian; Jordan-Sweet, Jean [IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598 (United States); Alptekin, Emre; Zhu, Frank [IBM Semiconductor Research and Development Center, 2070 Route 52, Hopewell Junction, New York 12533 (United States); Leith, Allen; Pfeifer, Brian D.; LaRose, J. D.; Russell, N. M. [TEL Epion Inc., 900 Middlesex Turnpike, Bldg. 6, Billerica, Massachusetts 01821 (United States)

2016-04-21

We report the formation of very uniform and smooth Ni(Pt)Si on epitaxially grown SiGe using Si gas cluster ion beam treatment after metal-rich silicide formation. The gas cluster ion implantation process was optimized to infuse Si into the metal-rich silicide layer and lowered the NiSi nucleation temperature significantly according to in situ X-ray diffraction measurements. This novel method which leads to more uniform films can also be used to control silicide depth in ultra-shallow junctions, especially for high Ge containing devices, where silicidation is problematic as it leads to much rougher interfaces.
NMOS contact resistance reduction with selenium implant into NiPt silicide

Science.gov (United States)

Rao, K. V.; Khaja, F. A.; Ni, C. N.; Muthukrishnan, S.; Darlark, A.; Lei, J.; Peidous, I.; Brand, A.; Henry, T.; Variam, N.; Erokhin, Y.

2012-11-01

A 25% reduction in NMOS contact resistance (Rc) was achieved by Selenium implantation into NiPt silicide film in VIISta Trident high-current single-wafer implanter. The Trident implanter is designed for shallow high-dose implants with high beam currents to maintain high throughput (for low CoO), with improved micro-uniformity and no energy contamination. The integration of Se implant was realized using a test chip dedicated to investigating silicide/junction related electrical properties and testable after silicidation. The silicide module processes were optimized, including the pre-clean (prior to RF PVD NiPt dep) and pre- and post-implant anneals. A 270°C soak anneal was used for RTP1, whereas a msec laser anneal was employed for RTP2 with sufficient process window (800-850°C), while maintaining excellent junction characteristics without Rs degradation.
Technology CAD of silicided Schottky barrier MOSFET for elevated source-drain engineering

International Nuclear Information System (INIS)

Saha, A.R.; Chattopadhyay, S.; Bose, C.; Maiti, C.K.

2005-01-01

Technology CAD has been used to study the performance of a silicided Schottky barrier (SB) MOSFET with gate, source and drain contacts realized with nickel-silicide. Elevated source-drain structures have been used towards the S/D engineering of CMOS devices. A full process-to-device simulation has been employed to predict the performance of sub-micron SB n-MOSFETs for the first time. A model for the diffusion and alloy growth kinetics has been incorporated in SILVACO-ATLAS and ATHENA to explore the processing and design parameter space for the Ni-silicided MOSFETs. The temperature and concentration dependent diffusion model for NiSi have been developed and necessary material parameters for nickel-silicide and epitaxial-Si have been incorporated through the C-interpreter function. Two-dimensional (2D) process-to-device simulations have also been used to study the dc and ac (RF) performance of silicided Schottky barrier (SB) n-MOSFETs. The extracted sheet resistivity, as a function of annealing temperature of the silicided S/D contacts, is found to be lower than the conventional contacts currently in use. It is also shown that the Technology CAD has the full capability to predict the possible dc and ac performance enhancement of a MOSFET with elevated S/D structures. While the simulated dc performance shows a clear enhancement, the RF analyses show no performance degradation in the cut-off frequency/propagation delay and also improve the ac performance due to the incorporation of silicide contacts in the S/D region
Technology CAD of silicided Schottky barrier MOSFET for elevated source-drain engineering

Energy Technology Data Exchange (ETDEWEB)

Saha, A.R. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India)]. E-mail: ars.iitkgp@gmail.com; Chattopadhyay, S. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India); School of Electrical, Electronics and Computer Engineering, University of Newcastle, Newcastle upon Tyne (United Kingdom); Bose, C. [Department of Electronics and Telecommunication Engineering, Jadavpur University, Calcutta 700032 (India); Maiti, C.K. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India)

2005-12-05

Technology CAD has been used to study the performance of a silicided Schottky barrier (SB) MOSFET with gate, source and drain contacts realized with nickel-silicide. Elevated source-drain structures have been used towards the S/D engineering of CMOS devices. A full process-to-device simulation has been employed to predict the performance of sub-micron SB n-MOSFETs for the first time. A model for the diffusion and alloy growth kinetics has been incorporated in SILVACO-ATLAS and ATHENA to explore the processing and design parameter space for the Ni-silicided MOSFETs. The temperature and concentration dependent diffusion model for NiSi have been developed and necessary material parameters for nickel-silicide and epitaxial-Si have been incorporated through the C-interpreter function. Two-dimensional (2D) process-to-device simulations have also been used to study the dc and ac (RF) performance of silicided Schottky barrier (SB) n-MOSFETs. The extracted sheet resistivity, as a function of annealing temperature of the silicided S/D contacts, is found to be lower than the conventional contacts currently in use. It is also shown that the Technology CAD has the full capability to predict the possible dc and ac performance enhancement of a MOSFET with elevated S/D structures. While the simulated dc performance shows a clear enhancement, the RF analyses show no performance degradation in the cut-off frequency/propagation delay and also improve the ac performance due to the incorporation of silicide contacts in the S/D region.
Structural and electronic properties of rare-earth silicide thin films at Si(111)

Energy Technology Data Exchange (ETDEWEB)

Dues, Christof; Schmidt, Wolf Gero; Sanna, Simone [Lehrstuhl fuer Theoretische Physik, Universitaet Paderborn (Germany)

2016-07-01

Rare-earth (RE) silicides thin films on silicon surfaces are currently of high interest. They grow nearly defect-free because of the small lattice mismatch, and exhibit very low Schottky-barriers on n-type silicon. They even give rise to the self-organized formation of RE silicide nanowires on the Si(001) and vicinal surfaces. Depending on the amount of deposited RE atoms, a plethora of reconstructions are observed for the RE silicide. While one monolayer leads to the formation of a 1 x 1-reconstruction, several monolayer thick silicides crystallize in a √(3) x √(3) R30 {sup circle} superstructure. Submonolayer RE deposition leads to different periodicities. In this work we investigate the formation of RE silicides thin films on Si(111) within the density functional theory. The energetically favored adsorption site for RE adatoms is determined calculating the potential energy surface. As prototypical RE, Dysprosium is used. Additional calculations are performed for silicides formed by different RE elements. We calculate structural properties, electronic band structures and compare measured and simulated STM images. We consider different terminations for the 5 x 2 reconstruction occurring in the submonolayer regime and investigate their stability by means of ab initio thermodynamics. The same method is employed to predict the stable silicide structure as a function of the deposited RE atoms.
Silicide/Silicon Heterointerfaces, Reaction Kinetics and Ultra-short Channel Devices

Science.gov (United States)

Tang, Wei

Nickel silicide is one of the electrical contact materials widely used on very large scale integration (VLSI) of Si devices in microelectronic industry. This is because the silicide/silicon interface can be formed in a highly controlled manner to ensure reproducibility of optimal structural and electrical properties of the metal-Si contacts. These advantages can be inherited to Si nanowire (NW) field-effect transistors (FET) device. Due to the technological importance of nickel silicides, fundamental materials science of nickel silicides formation (Ni-Si reaction), especially in nanoscale, has raised wide interest and stimulate new insights and understandings. In this dissertation, in-situ transmission electron microscopy (TEM) in combination with FET device characterization will be demonstrated as useful tools in nano-device fabrication as well as in gaining insights into the process of nickel silicide formation. The shortest transistor channel length (17 nm) fabricated on a vapor-liquid-solid (VLS) grown silicon nanowire (NW) has been demonstrated by controlled reaction with Ni leads on an in-situ transmission electron microscope (TEM) heating stage at a moderate temperature of 400 ºC. NiSi2 is the leading phase, and the silicide-silicon interface is an atomically sharp type-A interface. At such channel lengths, high maximum on-currents of 890 (microA/microm) and a maximum transconductance of 430 (microS/microm) were obtained, which pushes forward the performance of bottom-up Si NW Schottky barrier field-effect transistors (SB-FETs). Through accurate control over the silicidation reaction, we provide a systematic study of channel length dependent carrier transport in a large number of SB-FETs with channel lengths in the range of (17 nm -- 3.6 microm). Our device results corroborate with our transport simulations and reveal a characteristic type of short channel effects in SB-FETs, both in on- and off-state, which is different from that in conventional MOSFETs
Neutronic Analysis and Radiological Safety of RSG-GAS Reactor on 300 Grams Uranium Silicide Core

International Nuclear Information System (INIS)

Pande Made Udiyani; Lily Suparlina; Rokhmadi

2007-01-01

As starting of usage silicide U 250 g fuel element in the core of RSG-GAS and will be continued with usage of silicide U 300 g fuel element, hence done beforehand neutronic analyse and radiological safety of RSG-GAS. Calculation done by ORIGEN2.1 code to calculate source term, and also by PC-COSYMA code to calculate radiological safety of radioactive dispersion from RSG-GAS. Calculation of radioactive dispersion done at condition of reactor is postulated be happened an accident of LOCA causing one fuel element to melt. Neutronic analysis indicate that silicide U 250 g full core shall to be operated beforehand during 625 MWD before converted to silicide U 300 g core. During operation of transition core with mixture of silicide U 250 g and 300 g, all parameter fulfill criterion of safety Designed Balance core of silicide U 300 g will be reached at the time of fifth full core. Result of calculation indicate that through mixture core of silicide U 250 and 300 g proposed can form silicide U 300 g balance core of reactor RSG-GAS safely. Calculation of radiology safety by deterministic for silicide U 300 g balance core, and accident postulation which is equal to core of silicide U 250 g yield output in the form of radiation activity (radionuclide concentration in the air and deposition on the ground), radiation dose (collective and individual), radiation effect (short- and long-range), which accepted by society in each perceived sector. Result of calculation indicated that dose accepted by society is not pass permitted boundary for public society if happened accident. (author)
Silicide Schottky Contacts to Silicon: Screened Pinning at Defect Levels

Energy Technology Data Exchange (ETDEWEB)

Drummond, T.J.

1999-03-11

Silicide Schottky contacts can be as large as 0.955 eV (E{sub v} + 0.165 eV) on n-type silicon and as large as 1.05 eV (E{sub c} {minus} 0.07 eV) on p-type silicon. Current models of Schottky barrier formation do not provide a satisfactory explanation of occurrence of this wide variation. A model for understanding Schottky contacts via screened pinning at defect levels is presented. In the present paper it is shown that most transition metal silicides are pinned approximately 0.48 eV above the valence band by interstitial Si clusters. Rare earth disilicides pin close to the divacancy acceptor level 0.41 eV below the conduction band edge while high work function silicides of Ir and Pt pin close to the divacancy donor level 0.21 eV above the valence band edge. Selection of a particular defect pinning level depends strongly on the relative positions of the silicide work function and the defect energy level on an absolute energy scale.
Quantitative measurement for the microstructural parameters of nano-precipitates in Al-Mg-Si-Cu alloys

Energy Technology Data Exchange (ETDEWEB)

Li, Kai [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Electron Microscopy for Materials Science (EMAT), University of Antwerp, Antwerp B-2020 (Belgium); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Idrissi, Hosni [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Antwerp B-2020 (Belgium); Institute of Mechanics, Materials and Civil Engineering (iMMC), Université catholique de Louvain, Place Sainte Barbe 2, B-1348 Louvain-la-Neuve (Belgium); Sha, Gang [Gleiter Institute of Nano-science, Nanjing University of Science and Technology, Nanjing 210094 (China); Song, Min, E-mail: msong@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Lu, Jiangbo [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Antwerp B-2020 (Belgium); Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi' an Jiaotong University, Xi' an 710049 (China); Shi, Hui [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Antwerp B-2020 (Belgium); ArcelorMittal Global R& D Gent, Pres. J.F. Kennedylaan 3 Zelzate, Ghent B-9060 (Belgium); Wang, Wanlin [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Ringer, Simon P. [Australian Institute for Nanoscale Science and Technology, The University of Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Du, Yong [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Schryvers, Dominique [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Antwerp B-2020 (Belgium)

2016-08-15

Size, number density and volume fraction of nano-precipitates are important microstructural parameters controlling the strengthening of materials. In this work a widely accessible, convenient, moderately time efficient method with acceptable accuracy and precision has been provided for measurement of volume fraction of nano-precipitates in crystalline materials. The method is based on the traditional but highly accurate technique of measuring foil thickness via convergent beam electron diffraction. A new equation is proposed and verified with the aid of 3-dimensional atom probe (3DAP) analysis, to compensate for the additional error resulted from the hardly distinguishable contrast of too short incomplete precipitates cut by the foil surface. The method can be performed on a regular foil specimen with a modern LaB{sub 6} or field-emission-gun transmission electron microscope. Precisions around ± 16% have been obtained for precipitate volume fractions of needle-like β″/C and Q precipitates in an aged Al-Mg-Si-Cu alloy. The measured number density is close to that directly obtained using 3DAP analysis by a misfit of 4.5%, and the estimated precision for number density measurement is about ± 11%. The limitations of the method are also discussed. - Highlights: •A facile method for measuring volume fraction of nano-precipitates based on CBED •An equation to compensate for small invisible precipitates, with 3DAP verification •Precisions around ± 16% for volume fraction and ± 11% for number density.
Kinetics of nickel silicide growth in silicon nanowires: From linear to square root growth

International Nuclear Information System (INIS)

Yaish, Y. E.; Beregovsky, M.; Katsman, A.; Cohen, G. M.

2011-01-01

The common practice for nickel silicide formation in silicon nanowires (SiNWs) relies on axial growth of silicide along the wire that is initiated from nickel reservoirs at the source and drain contacts. In the present work the silicide intrusions were studied for various parameters including wire diameter (25-50 nm), annealing time (15-120 s), annealing temperature (300-440 deg. C), and the quality of the initial Ni/Si interface. The silicide formation was investigated by high-resolution scanning electron microscopy, high-resolution transmission electron microscopy (TEM), and atomic force microscopy. The main part of the intrusion formed at 420 deg. C consists of monosilicide NiSi, as was confirmed by energy dispersive spectroscopy STEM, selected area diffraction TEM, and electrical resistance measurements of fully silicided SiNWs. The kinetics of nickel silicide axial growth in the SiNWs was analyzed in the framework of a diffusion model through constrictions. The model calculates the time dependence of the intrusion length, L, and predicts crossover from linear to square root time dependency for different wire parameters, as confirmed by the experimental data.

Evaluation of the oxide and silicide fuels reactivity in the RSG-GAS core

International Nuclear Information System (INIS)

S, Tukiran; M S, Tagor; S, Lily; Pinem, S.

2000-01-01

Fuel exchange of The RSG-GAS reactor core from uranium oxide to uranium silicide in the same loading, density, and enrichment, that is, 250 gr, 2.98 gr/cm 3 , and 19.75 % respectively, will be performed in-step wise. In every cycle of exchange with 5/l mode, it is needed to evaluate the parameter of reactor core operation. One of the important operation parameters is fuel reactivity that gives effect to the core reactivity. The experiment was performed at core no. 36, BOC, low power which exist 2 silicide fuels. The evaluation was done based on the RSG-GAS control rod calibration consisting of 40 fuels and 8 control rod.s. From 40 fuels in the core, there are 2 silicide fuels, RI-225/A-9 and RI-224/C-3. For inserting 2 silicide fuels, the reactivity effect to the core must be know. To know this effect , it was performed fuels reactivity experiment, which based on control rod calibration. But in this case the RSG-GAS has no other fresh oxide fuel so that configuration of the RSG-GAS core was rearranged by taking out the both silicide fuels and this configuration is used as reference core. Then silicide fuel RI-224 was inserted to position F-3 replacing the fresh oxide fuel RI-260 so the different reactivity of the fuels is obtained. The experiment result showed that the fuel reactivity change is in amount of 12.85 cent (0.098 % ) The experiment result was compared to the calculation result, using IAFUEL code which amount to 13.49 cent (0.103 %) The result showed that the reactivity change of oxide to silicide fuel is small so that the fuel exchange from uranium oxide to uranium silicide in the first step can be done without any significant change of the operation parameter
Neutronic design of mixed oxide-silicide cores for the core conversion of rsg-gas reactor

International Nuclear Information System (INIS)

Sembiring, Tagor Malem; Tukiran; Pinem surian; Febrianto

2001-01-01

The core conversion of rsg-gas reactor from an all-oxide (U 3 O 8 -Al) core, through a series of mixed oxide-silicide core, to an all-silicide (U 3 Si 2 -Al) core for the same meat density of 2.96 g U/cc is in progress. The conversion is first step of the step-wise conversion and will be followed by the second step that is the core conversion from low meat density of silicide core, through a series of mixed lower-higher density of silicide core, to an all-higher meat density of 3.55 g/cc core. Therefore, the objectives of this work is to design the mixed cores on the neutronic performance to achieve safety a first full-silicide core for the reactor with the low uranium meat density of 2.96gU/cc. The neutronic design of the mixed cores was performed by means of Batan-EQUIL-2D and Batan-3DIFF computer codes for 2 and 3 dimension diffusion calculation, respectively. The result shows that all mixed oxide-silicide cores will be feasible to achieve safety a fist full-silicide core. The core performs the same neutronic core parameters as those of the equilibrium silicide core. Therefore, the reactor availability and utilization during the core conversion is not changed
Influence of IR-laser irradiation on α-SiC-chromium silicides ceramics

International Nuclear Information System (INIS)

Vlasova, M.; Marquez Aguilar, P.A.; Resendiz-Gonzalez, M.C.; Kakazey, M.; Bykov, A.; Gonzalez Morales, I.

2005-01-01

This project investigated the influence of IR-laser irradiation (λ = 1064 nm, P = 240 mW) on composite ceramics SiC-chromium silicides (CrSi 2 , CrSi, Cr 5 Si 3 ) by methods of X-ray diffraction, electron microscopy, atomic force microscopy, and X-ray microanalysis. Samples were irradiated in air. It was established that a surface temperature of 1990 K was required to melt chromium silicides, evaporate silicon from SiC, oxidize chromium silicides, and enrich superficial layer by carbon and chromium oxide
Tailoring of SiC nanoprecipitates formed in Si

Energy Technology Data Exchange (ETDEWEB)

Velisa, G., E-mail: gihan.velisa@cea.fr [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, 077125 Magurele (Romania); Trocellier, P. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Thomé, L. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, UMR8609, Bât. 108, 91405 Orsay (France); Vaubaillon, S. [CEA, INSTN, UEPTN, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Miro, S.; Serruys, Y.; Bordas, É. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Meslin, E. [CEA, DEN, Service de Recherches de Métallurgie Physique, F-91191 Gif-sur-Yvette (France); Mylonas, S. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, UMR8609, Bât. 108, 91405 Orsay (France); Coulon, P.E. [Ecole Polytechnique, Laboratoire des Solides Irradiés, CEA/DSM/IRAMIS-CNRS, 91128 Palaiseau Cedex (France); Leprêtre, F.; Pilz, A.; Beck, L. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France)

2013-07-15

The SiC synthesis through single-beam of C{sup +}, and simultaneous-dual-beam of C{sup +} and Si{sup +} ion implantations into a Si substrate heated at 550 °C has been studied by means of three complementary analytical techniques: nuclear reaction analysis (NRA), Raman, and transmission electron microscopy (TEM). It is shown that a broad distribution of SiC nanoprecipitates is directly formed after simultaneous-dual-beam (520-keV C{sup +} and 890-keV Si{sup +}) and single-beam (520-keV C{sup +}) ion implantations. Their shape appear as spherical (average size ∼4–5 nm) and they are in epitaxial relationship with the silicon matrix.
Prediction of barrier inhomogeneities and carrier transport in Ni-silicided Schottky diode

International Nuclear Information System (INIS)

Saha, A.R.; Dimitriu, C.B.; Horsfall, A.B.; Chattopadhyay, S.; Wright, N.G.; O'Neill, A.G.; Maiti, C.K.

2006-01-01

Based on Quantum Mechanical (QM) carrier transport and the effects of interface states, a theoretical model has been developed to predict the anomalous current-voltage (I-V) characteristics of a non-ideal Ni-silicided Schottky diode at low temperatures. Physical parameters such as barrier height, ideality factor, series resistance and effective Richardson constant of a silicided Schottky diode were extracted from forward I-V characteristics and are subsequently used for the simulation of both forward and reverse I-V characteristics using a QM transport model in which the effects of interface state and bias dependent barrier reduction are incorporated. The present analysis indicates that the effects of barrier inhomogeneity caused by incomplete silicide formation at the junction and the interface states may change the conventional current transport process, leading to anomalous forward and reverse I-V characteristics for the Ni-silicided Schottky diode
Analysis Of Core Management For The Transition Cores Of RSG-GAS Reactor To Full-Silicide Core

International Nuclear Information System (INIS)

Malem Sembiring, Tagor; Suparlina, Lily; Tukiran

2001-01-01

The core conversion of RSG-GAS reactor from oxide to silicide core with meat density of 2.96 g U/cc is still doing. At the end of 2000, the reactor has been operated for 3 transition cores which is the mixed core of oxide-silicide. Based on previous work, the calculated core parameter for the cores were obtained and it is needed 10 transition cores to achieve a full-silicide core. The objective of this work is to acquire the effect of the increment of the number of silicide fuel on the core parameters such as excess reactivity and shutdown margin. The measurement of the core parameters was carried out using the method of compensation of couple control rods. The experiment shows that the excess reactivity trends lower with the increment of the number of silicide fuel in the core. However, the shutdown margin is not change with the increment of the number of silicide fuel. Therefore, the transition cores can be operated safety to a full-silicide core
Far-infrared spectroscopy of thermally annealed tungsten silicide films

International Nuclear Information System (INIS)

Amiotti, M.; Borghesi, A.; Guizzetti, G.; Nava, F.; Santoro, G.

1991-01-01

The far-infrared transmittance spectrum of tungsten silicide has been observed for the first time. WSi 2 polycrystalline films were prepared by coevaporation and chemical-vapour deposition on silicon wafers, and subsequently thermally annealed at different temperatures. The observed structures are interpreted, on the basis of the symmetry properties of the crystal, such as infrared-active vibrational modes. Moreover, the marked lineshape dependence on annealing temperature enables this technique to analyse the formation of the solid silicide phases
Texture in thin film silicides and germanides: A review

International Nuclear Information System (INIS)

De Schutter, B.; De Keyser, K.; Detavernier, C.; Lavoie, C.

2016-01-01

Silicides and germanides are compounds consisting of a metal and silicon or germanium. In the microelectronics industry, silicides are the material of choice for contacting silicon based devices (over the years, CoSi_2, C54-TiSi_2, and NiSi have been adopted), while germanides are considered as a top candidate for contacting future germanium based electronics. Since also strain engineering through the use of Si_1_−_xGe_x in the source/drain/gate regions of MOSFET devices is an important technique for improving device characteristics in modern Si-based microelectronics industry, a profound understanding of the formation of silicide/germanide contacts to silicon and germanium is of utmost importance. The crystallographic texture of these films, which is defined as the statistical distribution of the orientation of the grains in the film, has been the subject of scientific studies since the 1970s. Different types of texture like epitaxy, axiotaxy, fiber, or combinations thereof have been observed in such films. In recent years, it has become increasingly clear that film texture can have a profound influence on the formation and stability of silicide/germanide contacts, as it controls the type and orientation of grain boundaries (affecting diffusion and agglomeration) and the interface energy (affecting nucleation during the solid-state reaction). Furthermore, the texture also has an impact on the electrical characteristics of the contact, as the orientation and size of individual grains influences functional properties such as contact resistance and sheet resistance and will induce local variations in strain and Schottky barrier height. This review aims to give a comprehensive overview of the scientific work that has been published in the field of texture studies on thin film silicide/germanide contacts.
Texture in thin film silicides and germanides: A review

Science.gov (United States)

De Schutter, B.; De Keyser, K.; Lavoie, C.; Detavernier, C.

2016-09-01

Silicides and germanides are compounds consisting of a metal and silicon or germanium. In the microelectronics industry, silicides are the material of choice for contacting silicon based devices (over the years, CoSi2, C54-TiSi2, and NiSi have been adopted), while germanides are considered as a top candidate for contacting future germanium based electronics. Since also strain engineering through the use of Si1-xGex in the source/drain/gate regions of MOSFET devices is an important technique for improving device characteristics in modern Si-based microelectronics industry, a profound understanding of the formation of silicide/germanide contacts to silicon and germanium is of utmost importance. The crystallographic texture of these films, which is defined as the statistical distribution of the orientation of the grains in the film, has been the subject of scientific studies since the 1970s. Different types of texture like epitaxy, axiotaxy, fiber, or combinations thereof have been observed in such films. In recent years, it has become increasingly clear that film texture can have a profound influence on the formation and stability of silicide/germanide contacts, as it controls the type and orientation of grain boundaries (affecting diffusion and agglomeration) and the interface energy (affecting nucleation during the solid-state reaction). Furthermore, the texture also has an impact on the electrical characteristics of the contact, as the orientation and size of individual grains influences functional properties such as contact resistance and sheet resistance and will induce local variations in strain and Schottky barrier height. This review aims to give a comprehensive overview of the scientific work that has been published in the field of texture studies on thin film silicide/germanide contacts.
Texture in thin film silicides and germanides: A review

Energy Technology Data Exchange (ETDEWEB)

De Schutter, B., E-mail: bob.deschutter@ugent.be; De Keyser, K.; Detavernier, C. [Department of Solid State Sciences, Ghent University, Ghent (Belgium); Lavoie, C. [IBM Research Division, T.J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598 (United States)

2016-09-15

Silicides and germanides are compounds consisting of a metal and silicon or germanium. In the microelectronics industry, silicides are the material of choice for contacting silicon based devices (over the years, CoSi{sub 2}, C54-TiSi{sub 2}, and NiSi have been adopted), while germanides are considered as a top candidate for contacting future germanium based electronics. Since also strain engineering through the use of Si{sub 1−x}Ge{sub x} in the source/drain/gate regions of MOSFET devices is an important technique for improving device characteristics in modern Si-based microelectronics industry, a profound understanding of the formation of silicide/germanide contacts to silicon and germanium is of utmost importance. The crystallographic texture of these films, which is defined as the statistical distribution of the orientation of the grains in the film, has been the subject of scientific studies since the 1970s. Different types of texture like epitaxy, axiotaxy, fiber, or combinations thereof have been observed in such films. In recent years, it has become increasingly clear that film texture can have a profound influence on the formation and stability of silicide/germanide contacts, as it controls the type and orientation of grain boundaries (affecting diffusion and agglomeration) and the interface energy (affecting nucleation during the solid-state reaction). Furthermore, the texture also has an impact on the electrical characteristics of the contact, as the orientation and size of individual grains influences functional properties such as contact resistance and sheet resistance and will induce local variations in strain and Schottky barrier height. This review aims to give a comprehensive overview of the scientific work that has been published in the field of texture studies on thin film silicide/germanide contacts.
Development of Silicide Coating on Molybdenum Alloy Cladding

International Nuclear Information System (INIS)

Lim, Woojin; Ryu, Ho Jin

2015-01-01

The molybdenum alloy is considered as one of the accident tolerant fuel (ATF) cladding materials due to its high temperature mechanical properties. However, molybdenum has a weak oxidation resistance at elevated temperatures. To modify the oxidation resistance of molybdenum cladding, silicide coating on the cladding is considered. Molybdenum silicide layers are oxidized to SiO 2 in an oxidation atmosphere. The SiO 2 protective layer isolates the substrate from the oxidizing atmosphere. Pack cementation deposition technique is widely adopted for silicide coating for molybdenum alloys due to its simple procedure, homogeneous coating quality and chemical compatibility. In this study, the pack cementation method was conducted to develop molybdenum silicide layers on molybdenum alloys. It was found that the Mo 3 Si layer was deposited on substrate instead of MoSi 2 because of short holding time. It means that through the extension of holding time, MoSi 2 layer can be formed on molybdenum substrate to enhance the oxidation resistance of molybdenum. The accident tolerant fuel (ATF) concept is to delay the process following an accident by reducing the oxidation rate at high temperatures and to delay swelling and rupture of fuel claddings. The current research for Atf can be categorized into three groups: First, modification of existing zirconium-based alloy cladding by improving the high temperature oxidation resistance and strength. Second, replacing Zirconium based alloys with alternative metallic materials such as refractory elements with high temperature oxidation resistance and strength. Third, designing alternative fuel structures using ceramic and composite systems
Oxidation behavior of molybdenum silicides and their composites

International Nuclear Information System (INIS)

Natesan, K.; Deevi, S. C.

2000-01-01

A key materials issue associated with the future of high-temperature structural silicides is the resistance of these materials to oxidation at low temperatures. Oxidation tests were conducted on Mo-based silicides over a wide temperature range to evaluate the effects of alloy composition and temperature on the protective scaling characteristics and testing regime for the materials. The study included Mo 5 Si 3 alloys that contained several concentrations of B. In addition, oxidation characteristics of MoSi 2 -Si 3 N 4 composites that contained 20--80 vol.% Si 3 N 4 were evaluated at 500--1,400 C
Microstructure and mechanical properties of metal/oxide and metal/silicide interfaces

International Nuclear Information System (INIS)

Shaw, L.; Miracle, D.; Abbaschian, R.

1995-01-01

Fracture energies of Al 2 O 3 /Nb interfaces and MoSi 2 /Nb interfaces with and without Al 2 O 3 coating were measured using sandwich-type chevron-notched specimens. The relations between the mechanical properties, microstructures, types of bonds at the interface and processing routes were explored. The fracture energy of the Al 2 O 3 /Nb interface was determined to be 9 J/m 2 and changed to 16 J/m 2 when Nb was pre-oxidized before the formation of the Al 2 O 3 /Nb interface. The fracture energy of the MoSi 2 /Nb interface could not be determined directly because of the formation of the interfacial compounds. However, the fracture energy at the MoSi 2 /Nb interfacial region was found to depend on the interfacial bond strength, roughness of interfaces and microstructure of interfacial compounds. The interfacial fracture energies of Al 2 O 3 with silicides, MoSi 2 , Nb 5 Si 3 , or (Nb, Mo)Si 2 were estimated to be about 16 J/m 2 , while the interfacial fracture energies between two silicides or between Nb and a silicide were larger than 34 J/m 2 . The measured fracture energies between two silicides or between Nb and a silicide were larger than 34 J/m 2 . The measured fracture energies of the various interfaces are discussed in terms of the interfacial microstructures and types of bonds at the interfaces
Evaluation of In-Core Fuel Management for the Transition Cores of RSG-GAS Reactor to Full-Silicide Core

International Nuclear Information System (INIS)

S, Tukiran; MS, Tagor; P, Surian

2003-01-01

The core conversion of RSG-GAS reactor from oxide to silicide core with meat density of 2.96 gU/cc has been done. The core-of RSG-GAS reactor has been operated full core of silicide fuels which is started with the mixed core of oxide-silicide start from core 36. Based on previous work, the calculated core parameter for the cores were obtained and it is needed 9 transition cores (core 36 - 44) to achieve a full-silicide core (core 45). The objective of this work is to acquire the effect of the increment of the number of silicide fuel on the core parameters. Conversion core was achieved by transition cores mixed oxide-silicide fuels. Each transition core is calculated and measured core parameter such as, excess reactivity and shutdown margin. Calculation done by Batan-EQUIL-2D code and measurement of the core parameters was carried out using the method of compensation of couple control rods. The results of calculation and experiment shows that the excess reactivity trends lower with the increment of the number of silicide fuel in the core. However, the shutdown margin is not change with the increment of the number of silicide fuel. Therefore, the transition cores can be operated safely to a full-silicide core
Thermal stability of Ni-Pt-Ta alloy silicides on epi-Si{sub 1-x}C{sub x}

Energy Technology Data Exchange (ETDEWEB)

Yoo, Jung-Ho; Chang, Hyun-Jin [Department of Ceramic Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Min, Byoung-Gi [Department of Ceramic Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Jusung Engineering Co., Ltd., 49, Neungpyeong-ri, Opo-eup, Gwangju-Si, Kyunggi-do 464-892 (Korea, Republic of); Ko, Dae-Hong [Department of Ceramic Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)], E-mail: dhko@yonsei.ac.kr; Cho, Mann-Ho [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Sohn, Hyunchul [Department of Ceramic Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Lee, Tae-Wan [Jusung Engineering Co., Ltd., 49, Neungpyeong-ri, Opo-eup, Gwangju-Si, Kyunggi-do 464-892 (Korea, Republic of)

2008-12-05

We investigated the silicide formation in Ni/epi-Si{sub 1-x}C{sub x} systems. Ni-Pt and Ni-Pt-Ta films were deposited on epi-Si{sub 1-x}C{sub x}/Si substrates by DC magnetron sputtering and processed at various temperatures. The sheet resistance of the silicide from the Ni alloy/epi-Si{sub 1-x}C{sub x} systems was maintained at low values compared to that from Ni/Si systems. By TEM and EDS analyses, we confirmed the presence of a Pt alloy layer at the top of the Ni-silicide layer. The stability of the silicide layer in the Ni alloy/epi-Si{sub 1-x}C{sub x} system is explained by not only the Pt rich layer on the top of the Ni-silicide layer, but also by the presence of a small amount of Pt in the Ni-silicide layer or at the grain boundaries. And both the thermal stability and the morphology of silicide were greatly improved by the addition of Ta in Ni-Pt films.
Exploitation of a self-limiting process for reproducible formation of ultrathin Ni1-xPtx silicide films

International Nuclear Information System (INIS)

Zhang Zhen; Zhu Yu; Rossnagel, Steve; Murray, Conal; Jordan-Sweet, Jean; Yang, Bin; Gaudet, Simon; Desjardins, Patrick; Kellock, Andrew J.; Ozcan, Ahmet; Zhang Shili; Lavoie, Christian

2010-01-01

This letter reports on a process scheme to obtain highly reproducible Ni 1-x Pt x silicide films of 3-6 nm thickness formed on a Si(100) substrate. Such ultrathin silicide films are readily attained by sputter deposition of metal films, metal stripping in wet chemicals, and final silicidation by rapid thermal processing. This process sequence warrants an invariant amount of metal intermixed with Si in the substrate surface region independent of the initial metal thickness, thereby leading to a self-limiting formation of ultrathin silicide films. The crystallographic structure, thickness, uniformity, and morphological stability of the final silicide films depend sensitively on the initial Pt fraction.
High temperature chlorosilane corrosion of iron and AISI 316L stainless steel

Science.gov (United States)

Aller, Joshua Loren

Chlorosilane gas streams are used at high temperatures (>500°C) throughout the semiconductor, polycrystalline silicon, and fumed silica industries, primarily as a way to refine, deposit, and produce silicon and silicon containing materials. The presence of both chlorine and silicon in chlorosilane species creates unique corrosion environments due to the ability of many metals to form both metal-chlorides and metal-silicides, and it is further complicated by the fact that many metal-chlorides are volatile at high-temperatures while metal-silicides are generally stable. To withstand the uniquely corrosive environments, expensive alloys are often utilized, which increases the cost of final products. This work focuses on the corrosion behavior of iron, the primary component of low-cost alloys, and AISI 316L, a common low-cost stainless steel, in environments representative of industrial processes. The experiments were conducted using a customized high temperature chlorosilane corrosion system that exposed samples to an atmospheric pressure, high temperature, chlorosilane environment with variable input amounts of hydrogen, silicon tetrachloride, and hydrogen chloride plus the option of embedding samples in silicon during the exposure. Pre and post exposure sample analysis including scanning electron microscopy, x-ray diffraction, energy dispersive x-ray spectroscopy, and gravimetric analysis showed the surface corrosion products varied depending on the time, temperature, and environment that the samples were exposed to. Most commonly, a volatile chloride product formed first, followed by a stratified metal silicide layer. The chlorine and silicon activities in the corrosion environment were changed independently and were found to significantly alter the corrosion behavior; a phenomenon supported by computational thermodynamic equilibrium simulations. It was found that in comparable environments, the stainless steel corroded significantly less than the pure iron. This
Uranium silicide activities at Babcock and Wilcox

International Nuclear Information System (INIS)

Noel, W.W.; Freim, J.B.

1983-01-01

Babcock and Wilcox, Naval Nuclear Fuel Division (NNFD) in conjunction with Argonne National Laboratory (ANL) is actively involved in the Reduced Enrichment Research Test Reactor (RERTR) Program to produce low enriched fuel elements for research reactors. B and W and ANL have undertaken a joint effort in which NNFD will fabricate two low enriched uranium (LEU), Oak Ridge Reactor (ORR) elements with uranium silicide fuel furnished by ANL. These elements are being fabricated for irradiation testing at Oak Ridge National Laboratory (ORNL). Concurrently with this program, NNFD is developing and implementing the uranium silicide and uranium aluminide fuel fabrication technology. NNFD is fabricating the uranium silicide ORR elements in a two-phase program, Development and Production. To summarize: 1. Full size fuel plates can be made with U 3 SiAl but the fabricator must prevent oxidation of the compact prior to hot roll bonding; 2. Providing the ANL U 3 Si x irradiation results are successful, NNFD plans to provide two ORR elements during February 1983; 3. NNFD is developing and implementing U 3 Si x and UAI x fuel fabrication technology to be operational in 1983; 4. NNFD can supply U 3 O 8 high enriched uranium (HEU) or low enriched uranium (LEU) research reactor elements; 5. NNFD is capable of providing high quality, cost competitive LEU or HEU research reactor elements to meet the needs of the customer
Further data of silicide fuel for the LEU conversion of JMTR

International Nuclear Information System (INIS)

Saito, M.; Futamura, Y.; Nakata, H.; Ando, H.; Sakurai, F.; Ooka, N.; Sakakura, A.; Ugajin, M.; Shirai, E.

1990-01-01

Silicide fuel data for the safety assessment of the JMTR LEU fuel conversion are being measured. The data include fission product release, thermal properties, behaviour under accident conditions, and metallurgical characteristics. The methods used in the experiments are discussed. Results of fission products release at high temperature are described. The release of iodine from the silicide fuel is considerably lower than for U-Al alloy fuel
Evaluation Of Oxide And Silicide Mixed Fuels Of The RSG-GAS Core

International Nuclear Information System (INIS)

Tukiran; Sembiring, Tagor Malem; Suparlina, Lily

2000-01-01

Fuel exchange of the RSG-GAS reactor core from uranium oxide to uranium silicide in the same loading, density, and enrichment, that is 250 gr, 2.98 gr/cm 3 , and 19.75%, respectively, will be performed in-step wise. In every cycle of exchange with 5/1 mode, it is needed to evaluate the parameter of reactor core operation. The parameters of the reactor operation observed are criticality mass of fuels, reactivity balance, and fuel reactivity that give effect to the reactor operation. The evaluation was done at beginning of cycle of the first and second transition core with compared between experiment and calculation results. The experiments were performed at transition core I and II, BOC, and low power. At transition core I, there are 2 silicide fuels (RI-224 and R1-225) in the core and then, added five silicide fuels (R1-226, R1-252, R1-263, and R1-264) to the core, so that there are seven silicide fuels in the transition core II. The evaluation was done based on the experiment of criticality, control rod calibration, fuel reactivity of the RSG-GAS transition core. For inserting 2 silicide fuels in the transition core I dan 7 fuels in the transition core II, the operation of RSG-GAS core fulfilled the safety margin and the parameter of reactor operation change is not occur drastically in experiment and calculation results. So that, the reactor was operated during 36 days at 15 MW, 540 MWD at the first transition core. The general result showed that the parameter of reactor operation change is small so that the fuel exchange from uranium oxide to uranium silicide in the next step can be done

Design and screening of nanoprecipitates-strengthened advanced ferritic alloys

Energy Technology Data Exchange (ETDEWEB)

Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chen, Tianyi [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sridharan, K. [Univ. of Wisconsin, Madison, WI (United States); He, Li [Univ. of Wisconsin, Madison, WI (United States)

2016-12-30

Advanced nuclear reactors as well as the life extension of light water reactors require advanced alloys capable of satisfactory operation up to neutron damage levels approaching 200 displacements per atom (dpa). Extensive studies, including fundamental theories, have demonstrated the superior resistance to radiation-induced swelling in ferritic steels, primarily inherited from their body-centered cubic (bcc) structure. This study aims at developing nanoprecipitates strengthened advanced ferritic alloys for advanced nuclear reactor applications. To be more specific, this study aims at enhancing the amorphization ability of some precipitates, such as Laves phase and other types of intermetallic phases, through smart alloying strategy, and thereby promote the crystalline®amorphous transformation of these precipitates under irradiation.
Improvement of Silicide Coating Method as Diffusion Barrier for U-Mo Dispersion Fuel

Energy Technology Data Exchange (ETDEWEB)

Nam, Ji Min; Kim, Sunghwan; Lee, Kyu Hong; Park, Jong Man [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-10-15

The excessive interaction between the U-Mo alloys and their surrounding Al matrix lead to excessive local swelling called 'pillowing'. For this reason, KAERI suggested several remedies such as alloying U-Mo with Ti, or Al matrix with Si. In addition, silicide or nitride coatings on the surface of U-Mo particles have also been proposed to hinder the growth of the interaction layer. In this study, centrifugally atomized U-Mo-Ti alloy powders were coated with silicide layers. The coating process was improved when compared to the previous coating in terms of the ball milling and heat treatment conditions. Subsequently, silicide coated U-Mo-Ti powders and pure aluminum powders were mixed and made into a compact for the annealing test. The compacts were annealed at 550 .deg. C for 2hr, and characterized using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). 1. Uniform, homogeneous, thickness controllable silicide layers were successfully coated on the surface of U-7wt%Mo-1wt%Ti powders. 2. U{sub 3}Si, U{sub 3}Si{sub 2} silicide layers formed on the surface of U-7wt%Mo-1wt%Ti powders, and were identified by XRD and EDS analyses.
Rare earths in iron and steelmaking and gaseous desulphurisation

International Nuclear Information System (INIS)

Kay, D.A.R.; Subramanian, S.V.; Meng, V.; Kumar, R.V.

1985-01-01

Rare earth (RE) additions, either as mischmetal or rare earth silicide, are used in many ladle treatment processes in modern ferrous metallurgy. In ironmaking they provide the basis for the control of graphite morphology in cast irons and in steelmaking additions are made to aluminum-killed steels for desulphurisation and the control of inclusion composition and morphology. Rare earth oxides may also be used in the desulphurisation of medium calorific value gaseous fuels and stack gases. In this paper, Ce-S-O and La-S-O phase stability diagrams are used to determine the role of the rare earths in the external processing of iron and steel, and gaseous desulphurisation
Formation of silicides in a cavity applicator microwave system

International Nuclear Information System (INIS)

Thompson, D.C.; Kim, H.C.; Alford, T.L.; Mayer, J.W.

2003-01-01

Metal silicides of nickel and cobalt are formed in a cavity applicator microwave system with a magnetron power of 1200 W and a frequency of 2.45 GHz. X-ray diffraction, Rutherford backscattering spectrometry, and four-point-probe measurements are used to identify the silicide phase present and layer thicknesses. Additional processing confirmed that the products attained from heating by microwaves do not differ appreciably from those attained in heating by thermal processes. Materials properties are used to explain microwave power absorption and demonstrate how to tailor a robust process in which thin film reactions can be attained and specific products isolated
Effects of Silicide Coating on the Interdiffusion between U-7Mo and Al

Energy Technology Data Exchange (ETDEWEB)

Nam, Ji Min; Kim, Ji Hyun; Kim, Sunghwan; Lee, Kyu Hong; Park, Jong Man; Jeong, Yong Jin; Kim, Ki Nam [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

The excessive interaction between the U-Mo alloys and their surrounding Al matrix lead to and excessive local swelling called 'pillowing'. For this reason, KAERI suggested several remedies such as alloying U-Mo with Ti, or Al matrix with Si. In addition, silicide, or nitride coatings on the surface of U-Mo particles have also been proposed to hinder the growth of interaction layer. In this study, centrifugally atomized U-7Mo alloy powders were coated with silicide layers at varying T (T = 900 and 1000 .deg. C) for 30 min, respectively. U-Mo alloy powder was blended with Si powders and subsequently heat-treated to form uranium-silicide coating layers on the surface of U-Mo alloy particles. For an annealing test, silicide-coated U-Mo alloy powders were made into a compact, and Al powders were used as a matrix. From EDS results, transformed uranium aluminide intermetallic compounds were mainly U(Al,Si)3. U(Al,Si)3 phase left the silicide coating layer behind, and formed inside of U-7Mo particles, as shown in Fig. 3(a) and (b). In the case of sample B, Al could not penetrate the silicide coating layer and the coating layers were remained constant, as shown in Fig. 3(c) and (d). From the results, we made a comparison between the compacts of sample A and B, and it was shown that Al can easily diffuse into unreacted Si and U{sub 3}Si{sub 5} mixed layer while U{sub 3}Si{sub 2} acted as a good diffusion barrier at 550 .deg. C though those layers had the same thickness.
Effects of Silicide Coating on the Interdiffusion between U-7Mo and Al

International Nuclear Information System (INIS)

Nam, Ji Min; Kim, Ji Hyun; Kim, Sunghwan; Lee, Kyu Hong; Park, Jong Man; Jeong, Yong Jin; Kim, Ki Nam

2015-01-01

The excessive interaction between the U-Mo alloys and their surrounding Al matrix lead to and excessive local swelling called 'pillowing'. For this reason, KAERI suggested several remedies such as alloying U-Mo with Ti, or Al matrix with Si. In addition, silicide, or nitride coatings on the surface of U-Mo particles have also been proposed to hinder the growth of interaction layer. In this study, centrifugally atomized U-7Mo alloy powders were coated with silicide layers at varying T (T = 900 and 1000 .deg. C) for 30 min, respectively. U-Mo alloy powder was blended with Si powders and subsequently heat-treated to form uranium-silicide coating layers on the surface of U-Mo alloy particles. For an annealing test, silicide-coated U-Mo alloy powders were made into a compact, and Al powders were used as a matrix. From EDS results, transformed uranium aluminide intermetallic compounds were mainly U(Al,Si)3. U(Al,Si)3 phase left the silicide coating layer behind, and formed inside of U-7Mo particles, as shown in Fig. 3(a) and (b). In the case of sample B, Al could not penetrate the silicide coating layer and the coating layers were remained constant, as shown in Fig. 3(c) and (d). From the results, we made a comparison between the compacts of sample A and B, and it was shown that Al can easily diffuse into unreacted Si and U 3 Si 5 mixed layer while U 3 Si 2 acted as a good diffusion barrier at 550 .deg. C though those layers had the same thickness
Nanoscale investigation of the interface situation of plated nickel and thermally formed nickel silicide for silicon solar cell metallization

Energy Technology Data Exchange (ETDEWEB)

Mondon, A., E-mail: andrew.mondon@ise.fraunhofer.de [Fraunhofer ISE, Heidenhofst. 2, D-79110 Freiburg (Germany); Wang, D. [Karlsruhe Nano Micro Facility (KNMF), H.-von-Helmholz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Zuschlag, A. [Universität Konstanz FB Physik, Jacob-Burckhardt-Str. 27, D-78464 Konstanz (Germany); Bartsch, J.; Glatthaar, M.; Glunz, S.W. [Fraunhofer ISE, Heidenhofst. 2, D-79110 Freiburg (Germany)

2014-12-30

Highlights: • Adhesion of metallization of fully plated nickel–copper contacts on silicon solar cells can be achieved by formation of nickel silicide at the cost of degraded cell performance. • Understanding of silicide growth mechanisms and controlled growth may lead to high performance together with excellent adhesion. • Silicide formation is well known from CMOS production from PVD-Ni on flat surfaces. Yet the deposition methods and therefore layer characteristics and the surface topography are different for plated metallization. • TEM analysis is performed for differently processed samples. • A nickel silicide growth model is created for plated Ni on textured silicon solar cells. - Abstract: In the context of nickel silicide formation from plated nickel layers for solar cell metallization, there are several open questions regarding contact adhesion and electrical properties. Nanoscale characterization by transmission electron microscopy has been employed to support these investigations. Interfacial oxides and silicide phases were investigated on differently prepared samples by different analytical methods associated with transmission electron microscopy analysis. Processing variations included the pre-treatment of samples before nickel plating, the used plating solution and the thermal budget for the nickel–silicon solid-state reaction. It was shown that interface oxides of only few nm thickness on both silicon and nickel silicide are present on the samples, depending on the chosen process sequence, which have been shown to play an important role in adhesion of nickel on silicide in an earlier publication. From sample pretreatment variations, conclusions about the role of an interfacial oxide in silicide formation and its influence on phase formation were drawn. Such an oxide layer hinders silicide formation except for pinhole sites. This reduces the availability of Ni and causes a silicide with low Ni content to form. Without an interfacial oxide
Analysis of impurity effect on Silicide fuels of the RSG-GAS core

International Nuclear Information System (INIS)

Tukiran-Surbakti

2003-01-01

Simulation of impurity effect on silicide fuel of the RSG-GAS core has been done. The aim of this research is to know impurity effect of the U-234 and U-236 isotopes in the silicide fuels on the core criticality. The silicide fuels of 250 g U loading and 19.75 of enrichment is used in this simulation. Cross section constant of fuels and non-structure material of core are generated by WIMSD/4 computer code, meanwhile impurity concentration was arranged from 0.01% to 2%. From the result of analysis can be concluded that the isotopes impurity in the fuels could make trouble in the core and the core can not be operated at critical after a half of its cycle length (350 MW D)
The influence of alloying on the phase formation sequence of ultra-thin nickel silicide films and on the inheritance of texture

Science.gov (United States)

Geenen, F. A.; Solano, E.; Jordan-Sweet, J.; Lavoie, C.; Mocuta, C.; Detavernier, C.

2018-05-01

The controlled formation of silicide materials is an ongoing challenge to facilitate the electrical contact of Si-based transistors. Due to the ongoing miniaturisation of the transistor, the silicide is trending to ever-thinner thickness's. The corresponding increase in surface-to-volume ratio emphasises the importance of low-energetic interfaces. Intriguingly, the thickness reduction of nickel silicides results in an abrupt change in phase sequence. This paper investigates the sequence of the silicides phases and their preferential orientation with respect to the Si(001) substrate, for both "thin" (i.e., 9 nm) and "ultra-thin" (i.e., 3 nm) Ni films. Furthermore, as the addition of ternary elements is often considered in order to tailor the silicides' properties, additives of Al, Co, and Pt are also included in this study. Our results show that the first silicide formed is epitaxial θ-Ni2Si, regardless of initial thickness or alloyed composition. The transformations towards subsequent silicides are changed through the additive elements, which can be understood through solubility arguments and classical nucleation theory. The crystalline alignment of the formed silicides with the substrate significantly differs through alloying. The observed textures of sequential silicides could be linked through texture inheritance. Our study illustrates the nucleation of a new phase drive to reduce the interfacial energy at the silicide-substrate interface as well as at the interface with the silicide which is being consumed for these sub-10 nm thin films.
Nanoscale investigation of the interface situation of plated nickel and thermally formed nickel silicide for silicon solar cell metallization

Science.gov (United States)

Mondon, A.; Wang, D.; Zuschlag, A.; Bartsch, J.; Glatthaar, M.; Glunz, S. W.

2014-12-01

In the context of nickel silicide formation from plated nickel layers for solar cell metallization, there are several open questions regarding contact adhesion and electrical properties. Nanoscale characterization by transmission electron microscopy has been employed to support these investigations. Interfacial oxides and silicide phases were investigated on differently prepared samples by different analytical methods associated with transmission electron microscopy analysis. Processing variations included the pre-treatment of samples before nickel plating, the used plating solution and the thermal budget for the nickel-silicon solid-state reaction. It was shown that interface oxides of only few nm thickness on both silicon and nickel silicide are present on the samples, depending on the chosen process sequence, which have been shown to play an important role in adhesion of nickel on silicide in an earlier publication. From sample pretreatment variations, conclusions about the role of an interfacial oxide in silicide formation and its influence on phase formation were drawn. Such an oxide layer hinders silicide formation except for pinhole sites. This reduces the availability of Ni and causes a silicide with low Ni content to form. Without an interfacial oxide a continuous nickel silicide of greater depth, polycrystalline modification and expected phase according to thermal budget is formed. Information about the nature of silicide growth on typical solar cell surfaces could be obtained from silicide phase and geometric observations, which were supported by FIB tomography. The theory of isotropic NiSi growth and orientation dependent NiSi2 growth was derived. By this, a very well performing low-cost metallization for silicon solar cells has been brought an important step closer to industrial introduction.
A Study on Silicide Coatings as Diffusion barrier for U-7Mo Dispersion Fuel

Energy Technology Data Exchange (ETDEWEB)

Won, Ju Jin; Kim, Sung Hwan; Lee, Kyu Hong; Jeong, Yong Jin; Kim, Ki Nam; Park, Jong Man; Lee, Chong Tak [KAERI, Daejeon (Korea, Republic of)

2016-05-15

Gamma phase U-Mo alloys are regarded as one of the promising candidates for advanced research reactor fuel when it comes to the irradiation performance. However, it has been reported that interaction layer formation between the UMo alloys and Al matrix degrades the irradiation performance of U-Mo dispersion fuel. The excessive interaction between the U-Mo alloys and their surrounding Al matrix lead to excessive local swelling called 'pillowing'. For this reason, KAERI suggested several remedies such as alloying U-Mo with Al matrix with Si. In addition, silicide or nitride coatings on the surface of U-Mo particles have also been proposed to hinder the growth of the interaction layer. In this study, centrifugally atomized U-7Mo alloy powders were coated with silicide layers at 900 .deg. C for 1hr. U-Mo alloy powder was mixed with MoSi{sub 2}, Si and ZrSi{sub 2} powders and subsequently heat-treated to form uranium-silicide coating layers on the surface of U-Mo alloy particles. Silicide coated U-Mo powders and characterized using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and X-ray diffractometer (XRD). The ZrSi{sub 2} coating layers has a thickness of about 1∼ 2μm. The surface of a silicide coated particle was very rough and silicide powder attached to the surface of the coating layer. 3. The XRD analysis of the coating layers showed that, they consisted of compounds such as U3Si{sub 2}, USi{sub 2}.
The Accident Analysis Due to Reactivity Insertion of RSG GAS 3.55 g U/cc Silicide Core

International Nuclear Information System (INIS)

Endiah Puji-Hastuti; Surbakti, Tukiran

2004-01-01

The fuels of RSG-GAS reactor was changed from uranium oxide with 250 g U of loading or 2.96 g U/cc of fuel loading to uranium silicide with the same loading. The silicide fuels can be used in higher density, staying longer in the reactor core and hence having a longer cycle length. The silicide fuel in RSG-GAS core was made up in step-wise by using mixed up core Firstly, it was used silicide fuel with 250 g U of loading and then, silicide fuel with 300 g U of loading (3.55 g U/cc of fuel loading). In every step-wise of fuel loading, it must be analyzed its safety margin. In this occasion, the reactivity accident of RSG-GAS core with 300 g U of silicide fuel loading is analyzed. The calculation was done using EUREKA-2/RR code available at P2TRR. The calculation was done by reactivity insertion at start up and power rangers. The worst case accident is transient due to control rod with drawl failure at start up by means of lowest initial power (0.1 W), either in power range. From all cases which have been done, the results of analysis showed that there is no anomaly and safety margin break at RSG-GAS core with 300 g U silicide fuel loading. (author)
Evaluation of anomalies during nickel and titanium silicide formation using the effective heat of formation mode

CSIR Research Space (South Africa)

Pretorius, R

1993-11-01

Full Text Available , as well as the observed sequence of growth of different silicide phases, are not in agree- ment with thermodynamic considerations [26]. In the case of the nickel silicides Ni,Si is nearly always found to be the first... to determine how the oxygen content in the silicon affects phase formation. We also show how the anomalous behaviour of titanium and nickel silicide formation can be explained thermodynamically by using the ?effective heat...
Analysis of quadrupole splitting of multiple Fe sites intermixed in Si(111) with Mössbauer spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kawauchi, Taizo, E-mail: kawauchi@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Zhang, Xiaowei [Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1, Oho, Tsukuba, Ibaraki 305-0801 (Japan); Fukutani, Katsuyuki [Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

2016-12-01

The iron silicide has various interesting phases both fundamentally and technologically, which have acquired much attention to date. Iron silicides are often fabricated on a Si substrate by a solid phase epitaxy method, and the initial stage of intermixing of iron atoms with substrate Si is of crucial importance for silicide fabrication, which remains to be clarified. Here, we have investigated the initial stage of the iron-silicide formation before crystallization with Mössbauer spectroscopy suited to characterization of magnetic and chemical properties of {sup 57}Fe atoms in materials. The sample was prepared by deposition of {sup 57}Fe of 1 nm on a Si(111) surface at 450 K. Conventional Mössbauer spectroscopy in the energy domain revealed presence of two iron sites with similar quadrupole splits and isomer shifts, which hampered complete analysis of this system. By combining the time-domain spectroscopy using polarized synchrotron radiation, we have separately analyzed the quadrupole splits and isomer shifts for the two iron sites. By using the theoretical simulation, furthermore, we successfully reproduced the experimentally observed time spectrum of the nuclear resonant scattering on the assumption that iron atoms randomly occupy the substitutional sites for Si at the initial stage of intermixing before crystallization of an iron silicide. - Highlights: • Quadrupole split of Fe in an iron silicide is measured by Mossbauer spectroscopy. • Two components are separately analyzed with time- and energy-domain spectra. • The time spectrum is well reproduced by numerical simulation. • Results indicate that Fe atoms randomly occupy two possible sites in Fe silicide.
Pt silicide/poly-Si Schottky diodes as temperature sensors for bolometers

Energy Technology Data Exchange (ETDEWEB)

Yuryev, V. A., E-mail: vyuryev@kapella.gpi.ru; Chizh, K. V.; Chapnin, V. A.; Mironov, S. A.; Dubkov, V. P.; Uvarov, O. V.; Kalinushkin, V. P. [A. M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilov Street, Moscow 119991 (Russian Federation); Senkov, V. M. [P. N. Lebedev Physical Institute of the Russian Academy of Sciences, 53 Leninskiy Avenue, Moscow 119991 (Russian Federation); Nalivaiko, O. Y. [JSC “Integral” – “Integral” Holding Management Company, 121A, Kazintsa I. P. Street, Minsk 220108 (Belarus); Novikau, A. G.; Gaiduk, P. I. [Belarusian State University, 4 Nezavisimosti Avenue, 220030 Minsk (Belarus)

2015-05-28

Platinum silicide Schottky diodes formed on films of polycrystalline Si doped by phosphorus are demonstrated to be efficient and manufacturable CMOS-compatible temperature sensors for microbolometer detectors of radiation. Thin-film platinum silicide/poly-Si diodes have been produced by a CMOS-compatible process on artificial Si{sub 3}N{sub 4}/SiO{sub 2}/Si(001) substrates simulating the bolometer cells. Layer structure and phase composition of the original Pt/poly-Si films and the Pt silicide/poly-Si films synthesized by a low-temperature process have been studied by means of the scanning transmission electron microscopy; they have also been explored by means of the two-wavelength X-ray structural phase analysis and the X-ray photoelectron spectroscopy. Temperature coefficient of voltage for the forward current of a single diode is shown to reach the value of about −2%/ °C in the temperature interval from 25 to 50 °C.
Molecular and supramolecular characterization of Ni(II)/losartan hydrophobic nanoprecipitate

Science.gov (United States)

Nascimento, Lorrayne O.; Goulart, Pedro P.; Correa, Jéssyca L.; Abrishamkar, Afshin; Da Silva, Jeferson G.; Mangrich, Antonio S.; de França, Amanda A.; Denadai, Ângelo M. L.

2014-09-01

In this work, a contribution to understanding of the formation of metal(II)/losartan hydrophobic nanoprecipitate is reported. A Ni(II)/Los system was prepared and characterized in solid state and in solution. Solubility studies confirmed the formation of hydrophobic precipitate. Obtained spectroscopic data suggest a sort of coordination between tetrazolic ring as well as OH, and a D4h geometry around the nickel cation. Thermodynamic studies demonstrated that complexation is a stepwise process, with equal enthalpic and entropic contributions for free energy of complexation. DLS and zeta potential titrations indicate the formation of stable nanoparticles of size and charge dependent on the molar ratio. Finally, rheological studies demonstrate a Bingham plastic behavior for Ni(II)/Los suspension.
Molybdenum silicide based materials and their properties

International Nuclear Information System (INIS)

Yao, Z.; Stiglich, J.; Sudarshan, T.S.

1999-01-01

Molybdenum disilicide (MoSi 2 ) is a promising candidate material for high temperature structural applications. It is a high melting point (2030 C) material with excellent oxidation resistance and a moderate density (6.24 g/cm 3 ). However, low toughness at low temperatures and high creep rates at elevated temperatures have hindered its commercialization in structural applications. Much effort has been invested in MoSi 2 composites as alternatives to pure molybdenum disilicide for oxidizing and aggressive environments. Molybdenum disilicide-based heating elements have been used extensively in high-temperature furnaces. The low electrical resistance of silicides in combination with high thermal stability, electron-migration resistance, and excellent diffusion-barrier characteristics is important for microelectronic applications. Projected applications of MoSi 2 -based materials include turbine airfoils, combustion chamber components in oxidizing environments, missile nozzles, molten metal lances, industrial gas burners, diesel engine glow plugs, and materials for glass processing. On this paper, synthesis, fabrication, and properties of the monolithic and composite molybdenum silicides are reviewed
Post-pulse detail metallographic examinations of low-enriched uranium silicide plate-type miniature fuel

International Nuclear Information System (INIS)

Yanagisawa, Kazuaki

1991-10-01

Pulse irradiation at Nuclear Safety Research Reactor (NSRR) was performed using low-enriched (19.89 w% 235 U) unirradiated silicide plate-type miniature fuel which had a density of 4.8 gU/cm 3 . Experimental aims are to understand the dimensional stability and to clarify the failure threshold of the silicide plate-type miniature fuel under power transient conditions through post-pulse detail metallographic examinations. A silicide plate-type miniature fuel was loaded into an irradiation capsule and irradiated by a single pulse. Deposited energies given in the experiments were 62, 77, 116 and 154 cal/g·fuel, which lead to corresponding peak fuel plate temperatures, 201 ± 28degC, 187 ± 10degC, 418 ± 74degC and 871 ± 74degC, respectively. Below 400degC, reliability and dimensional stability of the silicide plate fuel was sustained, and the silicide plate fuel was intact. Up to 540degC, wall-through intergranular crackings occurred in the Al-3%Mg alloy cladding. With the increase of the temperature, the melting of the aluminum cladding followed by recrystallization, the denudation of fuel core and the plate-through intergranular cracking were observed. With the increase of the temperature beyond 400degC, the bowing of fuel plate became significant. Above the temperature of 640degC molten aluminum partially reacted with the fuel core, partially flowed downward under the influence of surface tension and gravity, and partially formed agglomerations. Judging from these experimental observations, the fuel-plate above 400degC tends to reduce its dimensional stability. Despite of the apparent silicide fuel-plate failure, neither generation of pressure pulse nor that of mechanical energy occurred at all. (J.P.N.)
RA-3 core with uranium silicide fuel elements

International Nuclear Information System (INIS)

Abbate, Maximo J.; Sbaffoni, Maria M.

2000-01-01

Following on with studies on uranium silicide fuel elements, this paper reports some comparisons between the use of standard ECN [U 3 O 8 ] fuel elements and type P-06 [from U 3 Si 2 ] fuel elements in the RA-3 core.The first results showed that the calculated overall mean burn up is in agreement with that reported for the facility, which gives more confidence to the successive ones. Comparing the mentioned cores, the silicide one presents several advantages such as: -) a mean burn up increase of 18 %; -) an extraction burn up increase of 20 %; -) 37.4 % increase in full power days, for mean burn up. All this is meritorious for this fuel. Moreover, grouped and homogenized libraries were prepared for CITVAP code that will be used for planning experiments and other bidimensional studies. Preliminary calculations were also performed. (author)
Dislocation pinning effects induced by nano-precipitates during warm laser shock peening: Dislocation dynamic simulation and experiments

Science.gov (United States)

Liao, Yiliang; Ye, Chang; Gao, Huang; Kim, Bong-Joong; Suslov, Sergey; Stach, Eric A.; Cheng, Gary J.

2011-07-01

Warm laser shock peening (WLSP) is a new high strain rate surface strengthening process that has been demonstrated to significantly improve the fatigue performance of metallic components. This improvement is mainly due to the interaction of dislocations with highly dense nanoscale precipitates, which are generated by dynamic precipitation during the WLSP process. In this paper, the dislocation pinning effects induced by the nanoscale precipitates during WLSP are systematically studied. Aluminum alloy 6061 and AISI 4140 steel are selected as the materials with which to conduct WLSP experiments. Multiscale discrete dislocation dynamics (MDDD) simulation is conducted in order to investigate the interaction of dislocations and precipitates during the shock wave propagation. The evolution of dislocation structures during the shock wave propagation is studied. The dislocation structures after WLSP are characterized via transmission electron microscopy and are compared with the results of the MDDD simulation. The results show that nano-precipitates facilitate the generation of highly dense and uniformly distributed dislocation structures. The dislocation pinning effect is strongly affected by the density, size, and space distribution of nano-precipitates.

Nickel silicide thin films as masking and structural layers for silicon bulk micro-machining by potassium hydroxide wet etching

International Nuclear Information System (INIS)

Bhaskaran, M; Sriram, S; Sim, L W

2008-01-01

This paper studies the feasibility of using titanium and nickel silicide thin films as mask materials for silicon bulk micro-machining. Thin films of nickel silicide were found to be more resistant to wet etching in potassium hydroxide. The use of nickel silicide as a structural material, by fabricating micro-beams of varying dimensions, is demonstrated. The micro-structures were realized using these thin films with wet etching using potassium hydroxide solution on (1 0 0) and (1 1 0) silicon substrates. These results show that nickel silicide is a suitable alternative to silicon nitride for silicon bulk micro-machining
Core conversion study from silicide to molybdenum fuel in the Indonesian 30 MW multipurpose reactor G.A. Siwabessy (RSG-GAS)

International Nuclear Information System (INIS)

Sembiring, T.M.; Kuntoro, I.

2005-01-01

This paper describes the core conversion from silicide to molybdenum core through a series of silicide (2.96 gU cm -3 ) - molybdenum (3.55 gUcm -3 ) mixed transition cores for the Indonesian 30 MW-Multipurpose G.A. Siwabessy (RSGGAS) reactor. The core calculations are carried out using the two-dimensional multigroup neutron diffusion method code of Batan-EQUIL-2D. The calculated results showed that the proposed silicide-molybdenum mixed transition cores, using the same refueling/reshuffling scheme, meet the safety criteria and it can be used in safely converting from an all-silicide core to an all-molybdenum core. (author)
Multi-layered silicides coating for vanadium alloys for generation IV reactors

International Nuclear Information System (INIS)

Mathieu, S.; Chaia, N.; Vilasi, M.; Le Flem, M.

2012-01-01

The halide-activated pack-cementation technique was employed to fabricate a diffusion coating that is resistant both to isothermal and to cyclic oxidation in air at 650 degrees C on the surface of the V-4Cr-4Ti vanadium alloy that is a potential core component of future nuclear systems. A thermodynamic assessment determined the deposit conditions in terms of master alloy, activator, filler and temperature. The partial pressures of the main gaseous species (SiCl 4 , SiCl 2 and VCl 2 ) in the pack were calculated with the master alloy Si and the mixture VSi 2 + Si. The VSi 2 + Si master alloy was used to limit vanadium loss from the surface. The obtained coating consisted of multi-layered V x Si y silicides with an outer layer of VSi 2 . This silicide developed a protective layer of silica at 650 degrees C in air and was not susceptible to the pest phenomenon, unlike other refractory silicides (MoSi 2 , NbSi 2 ). We suggest that VSi 2 exhibits no risk of rapid degradation in the gas fast reactor (GFR) conditions. (authors)
Fuel-cycle cost comparisons with oxide and silicide fuels

International Nuclear Information System (INIS)

Matos, J.E.; Freese, K.E.

1982-01-01

This paper addresses fuel cycle cost comparisons for a generic 10 MW reactor with HEU aluminide fuel and with LEU oxide and silicide fuels in several fuel element geometries. The intention of this study is to provide a consistent assessment of various design options from a cost point of view. Fuel cycle cost benefits could result if a number of reactors were to utilize fuel elements with the same number or different numbers of the same standard fuel plate. Data are presented to quantify these potential cost benefits. This analysis shows that there are a number of fuel element designs using LEU oxide or silicide fuels that have either the same or lower total fuel cycle costs than the HEU design. Use of these fuels with the uranium densities considered requires that they are successfully demonstrated and licensed
The Leakage Current Improvement of a Ni-Silicided SiGe/Si Junction Using a Si Cap Layer and the PAI Technique

International Nuclear Information System (INIS)

Chang Jian-Guang; Wu Chun-Bo; Ji Xiao-Li; Ma Hao-Wen; Yan Feng; Shi Yi; Zhang Rong

2012-01-01

We investigate the leakage current of ultra-shallow Ni-silicided SiGe/Si junctions for 45 nm CMOS technology using a Si cap layer and the pre-amorphization implantation (PAI) process. It is found that with the conventional Ni silicide method, the leakage current of a p + (SiGe)—n(Si) junction is large and attributed to band-to-band tunneling and the generation-recombination process. The two leakage contributors can be suppressed quite effectively when a Si cap layer is added in the Ni silicide method. The leakage reduction is about one order of magnitude and could be associated with the suppression of the agglomeration of the Ni germano-silicide film. In addition, the PAI process after the application of a Si cap layer has little effect on improving the junction leakage but reduces the sheet resistance of the silicide film. As a result, the novel Ni silicide method using a Si cap combined with PAI is a promising choice for SiGe junctions in advanced technology. (cross-disciplinary physics and related areas of science and technology)
Safeguarding subcriticality during loading and shuffling operations in the higher density of the RSG-GAS's silicide core

International Nuclear Information System (INIS)

Sembiring, T.M.; Kuntoro, I.

2003-01-01

The core conversion program of the RSG-GAS reactor is to convert the all-oxide to all-silicide core. The silicide equilibrium core with fuel meat density of 3.55 gU cm -3 is an optimal core for RSG-GAS reactor and it can significantly increase the operation cycle length from 25 to 32 full power days. Nevertheless, the subcriticality of the shutdown core and the shutdown margin are lower than of the oxide core. Therefore, the deviation of subcriticality condition in the higher silicide core caused by the fuel loading and shuffling error should be reanalysed. The objective of this work is to analyse the sufficiency of the subcriticality condition of the shutdown core to face the worst condition caused by an error during loading and shuffling operations. The calculations were carried out using the 2-dimensional multigroup neutron diffusion code of Batan-FUEL. In the fuel handling error, the calculated results showed that the subcriticality condition of the shutdown higher density silicide equilibrium core of RSG-GAS can be maintained. Therefore, all fuel management steps are fixed in the present reactor operation manual can be applied in the higher silicide equilibrium core of RSG-GAS reactor. (author)
Kinetics of low pressure chemical vapor deposition of tungsten silicide from dichlorocilane reduction of tungsten hexafluoride

International Nuclear Information System (INIS)

Srinivas, D.; Raupp, G.B.; Hillman, J.

1990-01-01

The authors report on experiments to determine the intrinsic surface reaction rate dependences and film properties' dependence on local reactant partial pressures and wafer temperature in low pressure chemical vapor deposition (LPCVD) of tungsten silicide from dichlorosilane reduction of tungsten hexafluoride. Films were deposited in a commercial-scale Spectrum CVD cold wall single wafer reactor under near differential, gradientless conditions. Over the range of process conditions investigated, deposition rate was found to be first order in dichlorosillane and negative second order in tungsten hexafluoride partial pressure. The apparent activation energy in the surface reaction limited regime was found to be 70-120 kcal/mol. The silicon to tungsten ratio of as deposited silicide films ranged from 1.1 to 2.4, and increased with increasing temperature and dichlorosillane partial pressure, and decreased with increasing tungsten hexafluoride pressure. These results suggest that the apparent silicide deposition rate and composition are controlled by the relative rates of at least two competing reactions which deposit stoichiometric tungsten silicides and/or silicon
High resolution SEM characterization of nano-precipitates in ODS steels.

Science.gov (United States)

Jóźwik, Iwona; Strojny-Nędza, Agata; Chmielewski, Marcin; Pietrzak, Katarzyna; Kurpaska, Łukasz; Nosewicz, Szymon

2018-05-01

The performance of the present-day scanning electron microscopy (SEM) extends far beyond delivering electronic images of the surface topography. Oxide dispersion strengthened (ODS) steel is on of the most promising materials for the future nuclear fusion reactor because of its good radiation resistance, and higher operation temperature up to 750°C. The microstructure of ODS should not exceed tens of nm, therefore there is a strong need in a fast and reliable technique for their characterization. In this work, the results of low-kV SEM characterization of nanoprecipitates formed in the ODS matrix are presented. Application of highly sensitive photo-diode BSE detector in SEM imaging allowed for the registration of single nm-sized precipitates in the vicinity of the ODS alloys. The composition of the precipitates has been confirmed by TEM-EDS. © 2018 Wiley Periodicals, Inc.
Tungsten silicide contacts to polycrystalline silicon and silicon-germanium alloys

International Nuclear Information System (INIS)

Srinivasan, G.; Bain, M.F.; Bhattacharyya, S.; Baine, P.; Armstrong, B.M.; Gamble, H.S.; McNeill, D.W.

2004-01-01

Silicon-germanium alloy layers will be employed in the source-drain engineering of future MOS transistors. The use of this technology offers advantages in reducing series resistance and decreasing junction depth resulting in reduction in punch-through and SCE problems. The contact resistance of metal or metal silicides to the raised source-drain material is a serious issue at sub-micron dimensions and must be minimised. In this work, tungsten silicide produced by chemical vapour deposition has been investigated as a contact metallization scheme to both boron and phosphorus doped polycrystalline Si 1- x Ge x , with 0 ≤x ≤ 0.3. Cross bridge Kelvin resistor (CKBR) structures were fabricated incorporating CVD WSi 2 and polycrystalline SiGe. Tungsten silicide contacts to control polysilicon CKBR structures have been shown to be of high quality with specific contact resistance ρ c values 3 x 10 -7 ohm cm 2 and 6 x 10 -7 ohm cm 2 obtained to boron and phosphorus implanted samples respectively. The SiGe CKBR structures show that the inclusion of Ge yields a reduction in ρ c for both dopant types. The boron doped SiGe exhibits a reduction in ρ c from 3 x 10 -7 to 5 x 10 -8 ohm cm 2 as Ge fraction is increased from 0 to 0.3. The reduction in ρ c has been shown to be due to (i) the lowering of the tungsten silicide Schottky barrier height to p-type SiGe resulting from the energy band gap reduction, and (ii) increased activation of the implanted boron with increased Ge fraction. The phosphorus implanted samples show less sensitivity of ρ c to Ge fraction with a lowest value in this work of 3 x 10 -7 ohm cm 2 for a Ge fraction of 0.3. The reduction in specific contact resistance to the phosphorus implanted samples has been shown to be due to increased dopant activation alone
Flux pinning properties of YBa2Cu3O7-δ thin films containing a high density of nanoprecipitates: A comparative study to reveal size effects

Science.gov (United States)

Yamasaki, Hirofumi; Yamada, Hiroshi

2017-11-01

Temperature dependence of critical current density Jc(H, T) was measured in moderate magnetic fields (H ⊥ film) in two thermally co-evaporated YBa2Cu3O7-δ (YBCO) thin films (A, B) and two YBCO films (C, D) deposited using a pulsed-laser deposition method. All sample films were grown epitaxially with the c-axis perpendicular to the surface of a single-crystalline substrate. Transmission electron microscopy observation revealed that these four films contained a high density of nanoprecipitates with typical sizes of 3.6 - 5.0 nm (A), 5.0 - 7.1 nm (B), 7.0 - 10.1 nm (C) and 8.7 - 14.3 nm (D). Films A and B contained very fine nanoprecipitates, whose typical diameters Dtyp are smaller than double the estimated Ginzburg-Landau coherence length 2ξab at T = 77 K, and exhibited a steep increase of Jc with decreasing temperature. Whereas, film D, which contained relatively large nanoprecipitates (Dtyp > 2ξab at T ≤ 70 K), exhibited a gradual increase in Jc. This led to a remarkable crossing of the Jc(T) curves. The temperature dependence of Jc(H//c) under a fixed magnetic field is approximated by Jc ∼ (1 - T/Tc)m(1 + T/Tc)2 where the index m is larger for films containing finer precipitates; that is, m(A) > m(B) > m(C) > m(D). This means that finer nanoprecipitates generally cause steeper Jc increase at low temperatures, which is the origin of the observed crossing phenomenon. The experimental results are reasonably explained by several theoretical models based on the direct summation of elementary pinning forces fp calculated by core pinning interactions.
Formation of copper silicides by high dose metal vapor vacuum arc ion implantation

International Nuclear Information System (INIS)

Rong Chun; Zhang Jizhong; Li Wenzhi

2003-01-01

Si(1 1 1) was implanted by copper ions with different doses and copper distribution in silicon matrix was obtained. The as-implanted samples were annealed at 300 and 540 deg. C, respectively. Formation of copper silicides in as-implanted and annealed samples were studied. Thermodynamics and kinetics of the reaction were found to be different from reaction at copper-silicon interface that was applied in conventional studies of copper-silicon interaction. The defects in silicon induced by implantation and formation of copper silicides were recognized by Si(2 2 2) X-ray diffraction (XRD)
High temperature structural silicides

International Nuclear Information System (INIS)

Petrovic, J.J.

1997-01-01

Structural silicides have important high temperature applications in oxidizing and aggressive environments. Most prominent are MoSi 2 -based materials, which are borderline ceramic-intermetallic compounds. MoSi 2 single crystals exhibit macroscopic compressive ductility at temperatures below room temperature in some orientations. Polycrystalline MoSi 2 possesses elevated temperature creep behavior which is highly sensitive to grain size. MoSi 2 -Si 3 N 4 composites show an important combination of oxidation resistance, creep resistance, and low temperature fracture toughness. Current potential applications of MoSi 2 -based materials include furnace heating elements, molten metal lances, industrial gas burners, aerospace turbine engine components, diesel engine glow plugs, and materials for glass processing
Local solid phase growth of few-layer graphene on silicon carbide from nickel silicide supersaturated with carbon

International Nuclear Information System (INIS)

Escobedo-Cousin, Enrique; Vassilevski, Konstantin; Hopf, Toby; Wright, Nick; O'Neill, Anthony; Horsfall, Alton; Goss, Jonathan; Cumpson, Peter

2013-01-01

Patterned few-layer graphene (FLG) films were obtained by local solid phase growth from nickel silicide supersaturated with carbon, following a fabrication scheme, which allows the formation of self-aligned ohmic contacts on FLG and is compatible with conventional SiC device processing methods. The process was realised by the deposition and patterning of thin Ni films on semi-insulating 6H-SiC wafers followed by annealing and the selective removal of the resulting nickel silicide by wet chemistry. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to confirm both the formation and subsequent removal of nickel silicide. The impact of process parameters such as the thickness of the initial Ni layer, annealing temperature, and cooling rates on the FLG films was assessed by Raman spectroscopy, XPS, and atomic force microscopy. The thickness of the final FLG film estimated from the Raman spectra varied from 1 to 4 monolayers for initial Ni layers between 3 and 20 nm thick. Self-aligned contacts were formed on these patterned films by contact photolithography and wet etching of nickel silicide, which enabled the fabrication of test structures to measure the carrier concentration and mobility in the FLG films. A simple model of diffusion-driven solid phase chemical reaction was used to explain formation of the FLG film at the interface between nickel silicide and silicon carbide.
Behavior of silicon in nitric media. Application to uranium silicides fuels reprocessing

International Nuclear Information System (INIS)

Cheroux, L.

2001-01-01

Uranium silicides are used in some research reactors. Reprocessing them is a solution for their cycle end. A list of reprocessing scenarios has been set the most realistic being a nitric dissolution close to the classic spent fuel reprocessing. This uranium silicide fuel contains a lot of silicon and few things are known about polymerization of silicic acid in concentrated nitric acid. The study of this polymerization allows to point out the main parameters: acidity, temperature, silicon concentration. The presence of aluminum seems to speed up heavily the polymerization. It has been impossible to find an analytical technique smart and fast enough to characterize the first steps of silicic acid polymerization. However the action of silicic species on emulsions stabilization formed by mixing them with an organic phase containing TBP has been studied, Silicon slows down the phase separation by means of oligomeric species forming complex with TBP. The existence of these intermediate species is short and heating can avoid any stabilization. When non irradiated uranium silicide fuel is attacked by a nitric solution, aluminum and uranium are quickly dissolved whereas silicon mainly stands in solid state. That builds a gangue of hydrated silica around the uranium silicide particulates without preventing uranium dissolution. A small part of silicon passes into the solution and polymerize towards the highly poly-condensed forms, just 2% of initial silicon is still in molecular form at the end of the dissolution. A thermal treatment of the fuel element, by forming inter-metallic phases U-Al-Si, allows the whole silicon to pass into the solution and next to precipitate. The behavior of silicon in spent fuels should be between these two situations. (author)
Information for irradiation and post-irradiation of the silicide fuel element prototype P-07

International Nuclear Information System (INIS)

Abbate, Maximo J.; Sbaffoni, Maria M.

2003-01-01

Included in the 'Silicides' Project, developed by the Nuclear Fuels Department of the National Atomic Energy Commission (CNEA), it is foreseen the qualification of this type of fuel for research reactors in order to be used in the Argentine RA-3 reactor and to confirm the CNEA as an international supplier. The paper presents basic information on several parameters corresponding to the new silicide prototype, called P-07, to be taken into account for its irradiation, postirradiation and qualification. (author)
Formation of (Nd,Y)-silicides by sequential channeled implantation of Y and Nd ions

International Nuclear Information System (INIS)

Jin, S.; Bender, H.; Wu, M.F.; Vantomme, A.; Langouche, G.

2000-01-01

A buried hexagonal Nd 0.32 Y 0.68 Si 1.7 layer is formed by a sequential implantation of Y and Nd ions into (1 1 1)-oriented silicon wafers. The orientation relationship between the epitaxial Nd 0.32 Y 0.68 Si 1.7 and the silicon is (0 0 0 1) Nd 0.32 Y 0.68 Si 1.7 //(1 1 1) Si with Nd 0.32 Y 0.68 Si 1.7 // Si . High temperature annealing (1000 deg. C) results in a gradual transition into an orthorhombic ternary (Nd,Y)-silicide. Between the orthorhombic (Nd,Y)-silicide and the Si a preferential orientation relationship exists: (1 1 0) orth //(1 1(bar) 0) Si with orth // Si . However, as not all orthorhombic silicide grains follow this epitaxial relationship, the minimum yield in the Rutherford backscattering spectrometry (RBS) spectrum increases compared to the results after a low temperature annealing
Formation of (Nd,Y)-silicides by sequential channeled implantation of Y and Nd ions

Science.gov (United States)

Jin, S.; Bender, H.; Wu, M. F.; Vantomme, A.; Langouche, G.

2000-03-01

A buried hexagonal Nd0.32Y0.68Si1.7 layer is formed by a sequential implantation of Y and Nd ions into (1 1 1)-oriented silicon wafers. The orientation relationship between the epitaxial Nd0.32Y0.68Si1.7 and the silicon is (0 0 0 1)Nd0.32Y0.68Si1.7//(1 1 1)Si with Nd0.32Y0.68Si1.7//Si. High temperature annealing (1000°C) results in a gradual transition into an orthorhombic ternary (Nd,Y)-silicide. Between the orthorhombic (Nd,Y)-silicide and the Si a preferential orientation relationship exists: (1 1 0)orth//(1 1¯ 0)Si with orth//Si. However, as not all orthorhombic silicide grains follow this epitaxial relationship, the minimum yield in the Rutherford backscattering spectrometry (RBS) spectrum increases compared to the results after a low temperature annealing.
Fracture of niobium-base silicide coated alloy

International Nuclear Information System (INIS)

Davydova, A.D.; Zotov, Yu.P.; Ivashchenko, O.V.; Kushnareva, N.P.; Yarosh, I.P.

1990-01-01

Mechanical properties and character of fracture of Nb-W-Mo-Zr-C alloy composition with complex by composition and structure silicide coating under different states of stage-by-stage coating are studied. Structural features, character of fracture from ductile to quasibrittle transcrystalline one and, respectively, the composition plasticity level are defined by interrelation of fracture processes in coating, matrix plastic flow and possibility and way of stress relaxation on their boundary
pH-Switch Nanoprecipitation of Polymeric Nanoparticles for Multimodal Cancer Targeting and Intracellular Triggered Delivery of Doxorubicin.

Science.gov (United States)

Herranz-Blanco, Bárbara; Shahbazi, Mohammad-Ali; Correia, Alexandra R; Balasubramanian, Vimalkumar; Kohout, Tomáš; Hirvonen, Jouni; Santos, Hélder A

2016-08-01

Theranostic nanoparticles are emerging as potent tools for noninvasive diagnosis, treatment, and monitoring of solid tumors. Herein, an advanced targeted and multistimuli responsive theranostic platform is presented for the intracellular triggered delivery of doxorubicin. The system consists of a polymeric-drug conjugate solid nanoparticle containing encapsulated superparamagnetic iron oxide nanoparticles (IO@PNP) and decorated with a tumor homing peptide, iRGD. The production of this nanosystem is based on a pH-switch nanoprecipitation method in organic-free solvents, making it ideal for biomedical applications. The nanosystem shows sufficient magnetization saturation for magnetically guided therapy along with reduced cytotoxicity and hemolytic effects. IO@PNP are largely internalized by endothelial and metastatic cancer cells and iRGD decorated IO@PNP moderately enhance their internalization into endothelial cells, while no enhancement is found for the metastatic cancer cells. Poly(ethylene glycol)-block-poly(histidine) with pH-responsive and proton-sponge properties promotes prompt lysosomal escape once the nanoparticles are endocyted. In addition, the polymer-doxorubicin conjugate solid nanoparticles show both intracellular lysosomal escape and efficient translocation of doxorubicin to the nuclei of the cells via cleavage of the amide bond. Overall, IO@PNP-doxorubicin and the iRGD decorated counterpart demonstrate to enhance the toxicity of doxorubicin in cancer cells by improving the intracellular delivery of the drug carried in the IO@PNP. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Depth profile investigation of the incorporated iron atoms during Kr{sup +} ion beam sputtering on Si (001)

Energy Technology Data Exchange (ETDEWEB)

Khanbabaee, B., E-mail: khanbabaee@physik.uni-siegen.de [Solid State Physics, University of Siegen, D-57068 Siegen (Germany); Arezki, B.; Biermanns, A. [Solid State Physics, University of Siegen, D-57068 Siegen (Germany); Cornejo, M.; Hirsch, D. [Leibniz-Institut für Oberflächenmodifizierung e. V. (IOM), Permoserstraße 15, D-04318 Leipzig (Germany); Lützenkirchen-Hecht, D. [Abteilung Physik, Bergische Universität Wuppertal, D-42097 Wuppertal (Germany); Frost, F. [Leibniz-Institut für Oberflächenmodifizierung e. V. (IOM), Permoserstraße 15, D-04318 Leipzig (Germany); Pietsch, U. [Solid State Physics, University of Siegen, D-57068 Siegen (Germany)

2013-01-01

We investigate the incorporation of iron atoms during nano-patterning of Si surfaces induced by 2 keV Kr{sup +} ion beam erosion under an off-normal incidence angle of 15°. Considering the low penetration depth of the ions, we have used X-ray reflectivity (XRR) and X-ray absorption near edge spectroscopy (XANES) under grazing-incidence angles in order to determine the depth profile and phase composition of the incorporated iron atoms in the near surface region, complemented by secondary ion mass spectrometry and atomic force microscopy. XRR analysis shows the accumulation of metallic atoms within a near surface layer of a few nanometer thickness. We verify that surface pattern formation takes place only when the co-sputtered Fe concentration exceeds a certain limit. For high Fe concentration, the ripple formation is accompanied by the enhancement of Fe close to the surface, whereas no Fe enhancement is found for low Fe concentration at samples with smooth surfaces. Modeling of the measured XANES spectra reveals the appearance of different silicide phases with decreasing Fe content from the top towards the volume. - Highlights: ► We investigate the incorporation of iron atoms during nano-patterning of Si surfaces. ► Pattern formation occurs when the areal density of Fe exceeds a certain threshold. ► X-ray reflectivity shows a layering at near surface due to incorporated Fe atoms. ► It is shown that the patterning is accompanied with the appearance of Fe-rich silicide.

Effect of Utilization of Silicide Fuel with the Density 4.8 gU/cc on the Kinetic Parameters of RSG-GAS Reactor

International Nuclear Information System (INIS)

Setiyanto; Sembiring, Tagor M.; Pinem, Surian

2007-01-01

Presently, the RSG-GAS reactor using silicide fuel element of 2.96 gU/cc. For increasing reactor operation time, its planning to change to higher density fuel. The kinetic calculation of silicide core with density 4.8 gU/cc has been carried out, since it has an influence on the reactor operation safety. The calculated kinetic parameters are the effective delayed neutron fraction, the delayed neutron decay constant, prompt neutron lifetime and feedback reactivity coefficient very important for reactor operation safety. the calculation is performed in 2-dimensional neutron diffusion-perturbation method using modified Batan-2DIFF code. The calculation showed that the effective delayed neutron fraction is 7. 03256x10 -03 , total delay neutron time constant is 7.85820x10 -02 s -1 and the prompt neutron lifetime is 55.4900 μs. The result of prompt neutron lifetime smaller 10 % compare with silicide fuel of 4.8 gU/cc. The calculated results showed that all of the feedback reactivity coefficient silicide core 4.8 gU/cc is negative. Totally, the feedback reactivity coefficient of silicide fuel of 4.8 gU/cc is 10% less than that of silicide fuel of 2.96 gU/cc. The results shown that kinetic parameters result decrease compared with the silicide core with density 2.96 gU/cc, but no significant influence in the RSG-GAS reactor operation. (author)
Tracking the path of dislocations across ordered Al3Zr nano-precipitates in three dimensions

International Nuclear Information System (INIS)

Lefebvre, W.; Masquelier, N.; Houard, J.; Patte, R.; Zapolsky, H.

2014-01-01

Graphical abstract: -- We report on the shear–bypassing transition of chemically ordered Al 3 Zr nanoprecipitates. Observation of complex combinations of lattice translations, revealed by scanning transmission electron microscopy, is used as the signature of precipitate shearing during cold deformation. A method is proposed to build a three-dimensional atomic model of sheared particles from a set of three atomic scale projections. An estimation of the antiphase boundary energy of the Al 3 Zr structure is achieved via the comparison of experimental findings to a model of precipitation hardening
Solvent extraction studies of RERTR silicide fuels

International Nuclear Information System (INIS)

Gouge, Anthony P.

1983-01-01

Uranium silicide fuels, which are candidate RERTR fuel compositions, may require special considerations in solvent extraction reprocessing. Since Savannah River Plant may be reprocessing RERTR fuels as early as 1985, studies have been conducted at Savannah River Laboratory to demonstrate the solvent extraction behavior of this fuel. Results of solvent extraction studies with both unirradiated and irradiated fuel are presented along with the preliminary RERTR solvent extraction reprocessing flow sheet for Savannah River Plant. (author)
Reinvestigating nanoprecipitation via Box-Behnken design: a systematic approach.

Science.gov (United States)

Singh, Yuvraj; Ojha, Preeti; Srivastava, Mukesh; Chourasia, Manish K

2015-01-01

This work demonstrates Box-Behnken design (BBD)'s capability in exploring scientific principles governing a process, different from its use in process optimisation. We have investigated nanoprecipitation (NP) of temozolomide with polycaprolactone. Five factors, surfactant, stirring speed (SS), dropping rate (DR), phase-volume ratio (PVR) and drug-polymer ratio (DPR) were varied over three levels. Corresponding particle size (238.9 ± 42.24 nm), zeta potential (ZP, -5.92 ± 3.15 mV), poly dispersity index (PDI, 0.176 ± 0.06) and entrapment efficiency (EE, 65.74 ± 9.83%) were put into different polynomial equations. Analysis of variance, lack of fit tests and regression analysis was applied on these equations to determine the one with best fit. This selected equation was subsequently adapted as the model to describe influence of factors on NP. 3D response surface plots corresponding to models and diagnostic plots relatable to normality of residuals were also constructed. In conclusion, application of BBD efficiently strategised experimental foray conducted to elucidate NP.
Phase transformations in Higher Manganese Silicides

Energy Technology Data Exchange (ETDEWEB)

Allam, A. [MADIREL, UMR 7246 CNRS - Universite Aix-Marseille, av Normandie-Niemen, 13397 Marseille Cedex 20 (France); IM2NP, UMR 7334 CNRS - Universite Aix-Marseille, av Normandie-Niemen, Case 142, 13397 Marseille Cedex 20 (France); Boulet, P. [MADIREL, UMR 7246 CNRS - Universite Aix-Marseille, av Normandie-Niemen, 13397 Marseille Cedex 20 (France); Nunes, C.A. [Departamento de Engenharia de Materiais (DEMAR), Escola de Engenharia de Lorena (EEL), Universidade de Sao Paulo - USP, Caixa Postal 116, 12600-970 Lorena, Sao Paulo (Brazil); Sopousek, J.; Broz, P. [Masaryk University, Faculty of Science, Department of Chemistry, Kolarska 2, 611 37 Brno (Czech Republic); Masaryk University, Central European Institute of Technology, CEITEC, Kamenice 753/5, 625 00 Brno (Czech Republic); Record, M.-C., E-mail: m-c.record@univ-cezanne.fr [IM2NP, UMR 7334 CNRS - Universite Aix-Marseille, av Normandie-Niemen, Case 142, 13397 Marseille Cedex 20 (France)

2013-02-25

Highlights: Black-Right-Pointing-Pointer The phase transitions of the Higher Manganese Silicides were investigated. Black-Right-Pointing-Pointer The samples were characterised by XRD, DTA and DSC. Black-Right-Pointing-Pointer Mn{sub 27}Si{sub 47} is the stable phase at room temperature and under atmospheric pressure. Black-Right-Pointing-Pointer At around 800 Degree-Sign C, Mn{sub 27}Si{sub 47} is transformed into Mn{sub 15}Si{sub 26}. Black-Right-Pointing-Pointer The phase transition is of a second order. - Abstract: This work is an investigation of the phase transformations of the Higher Manganese Silicides in the temperature range [100-1200 Degree-Sign C]. Several complementary experimental techniques were used, namely in situ X-ray Diffraction (XRD), Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC). The evolution of both the lattice parameters and the thermal expansion coefficients was determined from in situ XRD measurements. The stability of the samples was investigated by thermal analysis (DTA) and Cp measurements (DSC). This study shows that Mn{sub 27}Si{sub 47} which is the stable phase at room temperature and under atmospheric pressure undergoes a phase transformation at around 800 Degree-Sign C. Mn{sub 27}Si{sub 47} is transformed into Mn{sub 15}Si{sub 26}. This phase transformation seems to be of a second order one. Indeed it was not evidenced by DTA and by contrast it appears on the Cp curve.
The electronic structure of 4d and 5d silicides

NARCIS (Netherlands)

Speier, W.; Kumar, L.; Sarma, D.D.; Groot, R.A. de; Fuggle, J.C.

1989-01-01

A systematic experimental and theoretical study of the electronic structure of stoichiometric silicides with Nb, Mo, Ta and W is presented. We have employed x-ray photoemission and bremsstrahlung isochromat spectroscopy as experimental techniques and interpreted the measured data by calculation of
Babcock and Wilcox plate fabrication experience with uranium silicide spherical fuel

International Nuclear Information System (INIS)

Todd, Lawrence E.; Pace, Brett W.

1996-01-01

This report is written to present the fuel fabrication experience of Babcock and Wilcox using atomized spherical uranium silicide powder. The intent is to demonstrate the ability to fabricate fuel plates using spherical powder and to provide useful information proceeding into the next phase of work using this type of fuel. The limited quantity of resources- spherical powder and time, did not allow for much process optimizing in this work scope. However, the information contained within provides optimism for the future of spherical uranium silicide fuel plate fabrication at Babcock and Wilcox.The success of assembling fuel elements with spherical powder will enable Babcock and Wilcox to reduce overall costs to its customers while still maintaining our reputation for providing high quality research and test reactor products. (author)
Silicon-germanium and platinum silicide nanostructures for silicon based photonics

Science.gov (United States)

Storozhevykh, M. S.; Dubkov, V. P.; Arapkina, L. V.; Chizh, K. V.; Mironov, S. A.; Chapnin, V. A.; Yuryev, V. A.

2017-05-01

This paper reports a study of two types of silicon based nanostructures prospective for applications in photonics. The first ones are Ge/Si(001) structures forming at room temperature and reconstructing after annealing at 600°C. Germanium, being deposited from a molecular beam at room temperature on the Si(001) surface, forms a thin granular film composed of Ge particles with sizes of a few nanometers. A characteristic feature of these films is that they demonstrate signs of the 2 x 1 structure in their RHEED patterns. After short-term annealing at 600°C under the closed system conditions, the granular films reconstruct to heterostructures consisting of a Ge wetting layer and oval clusters of Ge. A mixed type c(4x2) + p(2x2) reconstruction typical to the low-temperature MBE (Tgr Ge. The other type of the studied nanostructures is based on Pt silicides. This class of materials is one of the friendliest to silicon technology. But as silicide film thickness reaches a few nanometers, low resistivity becomes of primary importance. Pt3Si has the lowest sheet resistance among the Pt silicides. However, the development of a process of thin Pt3Si films formation is a challenging task. This paper describes formation of a thin Pt3Si/Pt2Si structures at room temperature on poly-Si films. Special attention is paid upon formation of poly-Si and amorphous Si films on Si3N4 substrates at low temperatures.
Mechanochemical synthesis and spark plasma sintering of the cerium silicides

Energy Technology Data Exchange (ETDEWEB)

Alanko, Gordon A.; Jaques, Brian; Bateman, Allyssa [Department of Materials Science and Engineering, College of Engineering, Boise State University, 1910 University Drive, Boise, ID 83725 (United States); Butt, Darryl P., E-mail: darrylbutt@boisestate.edu [Department of Materials Science and Engineering, College of Engineering, Boise State University, 1910 University Drive, Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Boulevard, Idaho Falls, ID 83401 (United States)

2014-12-15

Highlights: • Ce{sub 5}Si{sub 3}, Ce{sub 3}Si{sub 2}, CeSi, CeSi{sub 2−x} and CeSi{sub 2} were mechanochemically synthesized. • Temperature and pressure were monitored to investigate reaction progress. • All syntheses proceeded through a MSR event followed by rapid solid-state diffusion. • Milling time before MSR correlates well with effective heat of formation. • Some synthesized material was densified by spark plasma sintering. - Abstract: The cerium silicides, Ce{sub 5}Si{sub 3}, Ce{sub 3}Si{sub 2}, CeSi, CeSi{sub 2−y}, and CeSi{sub 2−x}, have been prepared from the elements by mechanochemical processing in a planetary ball mill. Preparation of the cerium silicide Ce{sub 5}Si{sub 4} was unsuccessfully attempted and potential reasons for this are discussed. Temperature and pressure of the milling vial were monitored in situ to gain insight into the mechanochemical reaction kinetics, which include a mechanically-induced self-propagating reaction (MSR). Some prepared powders were consolidated by spark plasma sintering to high density. Starting materials, as-milled powders, and consolidated samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results obtained help elucidate key questions in mechanochemical processing of intermetallics, showing first phase formation similar to thin films, MSR ignition times that are composition- and milling speed-dependent, and sensitivity of stable compound formation on the impact pressure. The results demonstrate mechanochemical synthesis as a viable technique for rare earth silicides.
Towards the improvement of the oxidation resistance of Nb-silicides in situ composites: A solid state diffusion approach

International Nuclear Information System (INIS)

Mathieu, S.; Knittel, S.; François, M.; Portebois, L.; Mathieu, S.; Vilasi, M.

2014-01-01

Highlights: •Local equilibrium is attained during oxidation at phase boundaries (steady state conditions). •A solid state diffusion model explains the oxidation mechanism of Nb-silicides composites. •The Nb ss fraction is not the only parameters governing the oxidation rate of Nb-silicides. •Aluminium increases the thermodynamic activity of Si in the Nb-silicides composites. •The results indicate the need to develop a Nb–Ti–Hf–Al–Cr–Si thermodynamic database. -- Abstract: The present study focuses on the oxidation mechanism of Nb-silicide composites and on the effect of the composition on the oxidation rate at 1100 °C. A theoretical approach is proposed based on experimental results and used to optimise the oxidation resistance. The growth model based on multiphase diffusion was experimentally tested and confirmed by manufacturing seven composites with different compositions. It was also found that the effect of the composition has to be evaluated at 1100 °C within a short time duration (50 h), where the oxide scale and the internal oxidation zone both grow according to parabolic kinetics
Phase analyses of silicide or nitride coated U–Mo and U–Mo–Ti particle dispersion fuel after out-of-pile annealing

Energy Technology Data Exchange (ETDEWEB)

Kim, Woo Jeong [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong, Daejeon 305-353 (Korea, Republic of); Palancher, Hervé [CEA, DEN, DEC, F-13108 Saint Paul Lez Durance Cedex (France); Ryu, Ho Jin, E-mail: hojinryu@kaist.ac.kr [Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong, Daejeon 305-701 (Korea, Republic of); Park, Jong Man; Nam, Ji Min [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong, Daejeon 305-353 (Korea, Republic of); Bonnin, Anne [CEA, DEN, DEC, F-13108 Saint Paul Lez Durance Cedex (France); ESRF, 6, rue J. Horowitz, F-38000 Grenoble Cedex (France); Honkimäki, Veijo [ESRF, 6, rue J. Horowitz, F-38000 Grenoble Cedex (France); Charollais, François [CEA, DEN, DEC, F-13108 Saint Paul Lez Durance Cedex (France); Lemoine, Patrick [CEA, DEN, DISN, 91191 Gif sur Yvette (France)

2014-03-15

Highlights: • Silicide or nitride layers were coated on atomized U–Mo or U–Mo–Ti powder. • The constituent phases after annealing were identified through high-energy XRD. • U{sub 3}Si{sub 5} and U{sub 4}Mo(Mo{sub x}Si{sub 1−x})Si{sub 2} were identified in the silicide coating layers. • UN was identified for U–Mo particles and UN and U{sub 4}N{sub 7} formed on U–Mo–Ti particles. -- Abstract: The coating of silicide or nitride layers on U–7 wt%Mo or U–7 wt%Mo–1 wt%Ti particles has been proposed for the minimization of the interaction phase growth in U–Mo/Al dispersion fuel during irradiation. Out-of-pile annealing tests show reduced inter-diffusion by forming silicide or nitride protective layers on U–Mo and U–Mo–Ti particles. To characterize the constituent phases of the coated layers on U–Mo and U–Mo–Ti particles and the interaction phases of coated U–Mo and U–Mo–Ti particle dispersed Al matrix fuel, synchrotron X-ray diffraction experiments have been performed. It was identified that silicide coating layers consisted mainly of U{sub 3}Si{sub 5} and U{sub 4}Mo(Mo{sub x}Si{sub 1−x})Si{sub 2}, and nitride coating layers were composed of mainly UN and U{sub 4}N{sub 7}. The interaction phases obtained after annealing of coated U–Mo and U–Mo–Ti particle dispersion samples were identical to those found in U–Mo/Al–Si and U–Mo/Al systems. Nitride-coated particles showed less interaction formation than silicide-coated particles after annealing at 580 °C for 1 h owing to the higher susceptibility to breakage of the silicide coating layers during hot extrusion.
Optical anisotropy of quasi-1D rare-earth silicide nanostructures on Si(001)

Energy Technology Data Exchange (ETDEWEB)

Chandola, S., E-mail: sandhya.chandola@isas.de [Leibniz-Institut für Analytische Wissenschaften – ISAS – e.V., Schwarzschildstraße 8, 12489 Berlin (Germany); Speiser, E.; Esser, N. [Leibniz-Institut für Analytische Wissenschaften – ISAS – e.V., Schwarzschildstraße 8, 12489 Berlin (Germany); Appelfeller, S.; Franz, M.; Dähne, M. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin (Germany)

2017-03-31

Highlights: • Reflectance anisotropy spectroscopy (RAS) is capable of distinguishing optically between the semiconducting wetting layer and the metallic nanowires of rare earth (Tb and Dy) silicide nanostructures grown on vicinal Si(001). • The spectra of the wetting layer show a distinctive line shape with a large peak appearing at 3.8 eV, which is assigned to the formation of 2 × 3 and 2 × 4-like subunits of the 2 × 7 reconstruction. The spectra of the metallic nanowires show peaks at the E{sub 1} and E{sub 2} transitions of bulk Si which is assigned to strong substrate strain induced by the nanowires. • The optical anisotropy of the Tb nanowires is larger than for the Dy nanowires, which is related to the preferential formation of more strained bundles as well as larger areas of clean Si surfaces in the case of Tb. • RAS is shown to be a powerful addition to surface science techniques for studying the formation of rare-earth silicide nanostructures. Its surface sensitivity and rapidity of response make it an ideal complement to the slower but higher resolution of scanning probes of STM and AFM. - Abstract: Rare earth metals are known to interact strongly with Si(001) surfaces to form different types of silicide nanostructures. Using STM to structurally characterize Dy and Tb silicide nanostructures on vicinal Si(001), it will be shown that reflectance anisotropy spectroscopy (RAS) can be used as an optical fingerprint technique to clearly distinguish between the formation of a semiconducting two-dimensional wetting layer and the metallic one-dimensional nanowires. Moreover, the distinctive spectral features can be related to structural units of the nanostructures. RAS spectra of Tb and Dy nanostructures are found to show similar features.
Cross-Bridge Kelvin Resistor (CBKR) structures for silicide-semiconductor junctions characterization

NARCIS (Netherlands)

Stavitski, N.; van Dal, M.J.H.; Klootwijk, J.H.; Wolters, Robertus A.M.; Kovalgin, Alexeij Y.; Schmitz, Jurriaan

2006-01-01

Analyzing the contact geometry factors for the conventional CBKR structures, it appeared that the contact geometries conventionally used for the metal-to-silicide contact resistance measurements were not always satisfactory to reveal the specific contact resistance values. To investigate these
Synthesis of molybdenum borides and molybdenum silicides in molten salts and their oxidation behavior in an air-water mixture

NARCIS (Netherlands)

Kuznetsov, S.A.; Kuznetsova, S.V.; Rebrov, E.V.; Mies, M.J.M.; Croon, de M.H.J.M.; Schouten, J.C.

2005-01-01

The formation of various coatings in molybdenum-boron and molybdenum-silicon systems was investigated. Boronizing and siliciding treatments were conducted in molten salts under inert gas atm. in the 850-1050 DegC temp. range for 7 h. The presence of boride (e.g. Mo2B, MoB, Mo2B5) and silicide
Influence of impurities on silicide contact formation

International Nuclear Information System (INIS)

Kazdaev, Kh.R.; Meermanov, G.B.; Kazdaev, R.Kh.

2002-01-01

Research objectives of this work are to investigate the influence of light impurities implantation on peculiarities of the silicides formation in molybdenum monocrystal implanted by silicon, and in molybdenum films sputtered on silicon substrate at subsequent annealing. Implantation of the molybdenum samples was performed with silicon ions (90 keV, 5x10 17 cm -2 ). Phase identification was performed by X ray analysis with photographic method of registration. Analysis of the results has shown the formation of the molybdenum silicide Mo 3 Si at 900 deg. C. To find out the influence of impurities present in the atmosphere (C,N,O) on investigated processes we have applied combined implantation. At first, molybdenum was implanted with ions of the basic component (silicon) and then -- with impurities ions. Acceleration energies (40keV for C, 45 keV for N and 50 keV for O) were chosen to obtain the same distribution profiles for basic and impurities ions. Ion doses were 5x10 17 cm -2 for Si-ions and 5x10 16 cm -2 - for impurities. The most important results are reported here. The first, for all three kinds of impurities the decreased formation temperatures of the phase Mo 3 Si were observed; in the case of C and N it was ∼100 deg. and in the case of nitrogen - ∼200 deg. Further, simultaneously with the Mo 3 Si phase, the appearance of the rich-metal phase Mo 5 Si 3 was registered (not observed in the samples without additional implantation). In case of Mo/Si-structure, the implantation of the impurities (N,O) was performed to create the peak concentration (∼4at/%) located in the middle of the molybdenum film (∼ 150nm) deposited on silicon substrate. Investigation carried out on unimplanted samples showed the formation of the silicide molybdenum MoSi 2 , observed after annealing at temperatures 900/1000 deg. C, higher than values 500-600 deg. C reported in other works. It is discovered that electrical conductivity of Mo 5 Si 3 -films synthesized after impurities
Fuel cycle cost comparisons with oxide and silicide fuels

Energy Technology Data Exchange (ETDEWEB)

Matos, J E; Freese, K E [RERTR Program, Argonne National Laboratory (United States)

1983-09-01

This paper addresses fuel cycle cost comparisons for a generic 10 MW reactor with HEU aluminide fuel and with LEU oxide and silicide fuels in several fuel element geometries. The intention of this study is to provide a consistent assessment of various design options from a cost point of view. The status of the development and demonstration of the oxide and silicide fuels are presented in several papers in these proceedings. Routine utilization of these fuels with the uranium densities considered here requires that they are successfully demonstrated and licensed. Thermal-hydraulic safety margins, shutdown margins, mixed cores, and transient analyses are not addressed here, but analyses of these safety issues are in progress for a limited number of the most promising design options. Fuel cycle cost benefits could result if a number of reactors were to utilize fuel elements with the same number or different numbers of the same standard fuel plate. Data is presented to quantify these potential cost benefits. This analysis shows that there are a number of fuel element designs using LEU oxide or silicide fuels that have either the same or lower total fuel cycle costs than the HEU design. Use of these fuels with the uranium densities considered requires that they are successfully demonstrated and licensed. All safety criteria for the reactor with these fuel element designs need to be satisfied as well. With LEU oxide fuel, 31 g U/cm{sup 3} 1 and 0.76 mm--thick fuel meat, elements with 18-22 plates 320-391 g {sup 235}U) result in the same or lower total costs than with the HEU element 23 plates, 280 g {sup 235}U). Higher LEU loadings (more plates per element) are needed for larger excess reactivity requirements. However, there is little cost advantage to using more than 20 of these plates per element. Increasing the fuel meat thickness from 0.76 mm to 1.0 mm with 3.1 g U/cm{sup 3} in the design with 20 plates per element could result in significant cost reductions if the
Detailed analysis of uranium silicide dispersion fuel swelling

International Nuclear Information System (INIS)

Hofmann, G.L.; Ryu, Woo-Seog

1991-01-01

Swelling of U 3 Si and U 3 Si 2 is analyzed. The growth of fission gas bubbles appears to be affected by fission rate, fuel loading, and micro structural change taking place in the fuel compounds during irradiation. Several mechanisms are explored to explain the observations. The present work is aimed at a better understanding of the basic swelling phenomenon in order to accurately model irradiation behavior of uranium silicide dispersion fuel. (orig.)
Secondary neutral mass spectrometry depth profile analysis of silicides

International Nuclear Information System (INIS)

Beckmann, P.; Kopnarski, M.; Oechsner, H.

1985-01-01

The Direct Bombardment Mode (DBM) of Secondary Neutral Mass Spectrometry (SNMS) has been applied for depth profile analysis of two different multilayer systems containing metal silicides. Due to the extremely high depth resolution obtained with low energy SNMS structural details down to only a few atomic distances are detected. Stoichiometric information on internal oxides and implanted material is supplied by the high quantificability of SNMS. (Author)
Influence of Al addition on phase transformation and thermal stability of nickel silicides on Si(0 0 1)

International Nuclear Information System (INIS)

Huang, Shih-Hsien; Twan, Sheng-Chen; Cheng, Shao-Liang; Lee, Tu; Hu, Jung-Chih; Chen, Lien-Tai; Lee, Sheng-Wei

2014-01-01

Highlights: ► The presence of Al slows down the Ni 2 Si–NiSi phase transformation but significantly promotes the NiSi 2−x Al x formation. ► The behavior of phase transformation strongly depends on the Al concentration of the initial Ni 1−x Al x alloys. ► The Ni 0.91 Al 0.09 /Si system exhibits remarkably improved thermal stability, even after high temperature annealing for 1000 s. ► The relationship between microstructures, electrical property, and thermal stability of Ni(Al) silicides is discussed. -- Abstract: The influence of Al addition on the phase transformation and thermal stability of Ni silicides on (0 0 1)Si has been systematically investigated. The presence of Al atoms is found to slow down the Ni 2 Si–NiSi phase transformation but significantly promote the NiSi 2−x Al x formation during annealing. The behavior of phase transformation strongly depends on the Al concentration of the initial Ni 1−x Al x alloys. Compared to the Ni 0.95 Pt 0.05 /Si and Ni 0.95 Al 0.05 /Si system, the Ni 0.91 Al 0.09 /Si sample exhibits remarkably enhanced thermal stability, even after high temperature annealing for 1000 s. The relationship between microstructures, electrical property, and thermal stability of Ni silicides is discussed to elucidate the role of Al during the Ni 1−x Al x alloy silicidation. This work demonstrated that thermally stable Ni 1−x Al x alloy silicides would be a promising candidate as source/drain (S/D) contacts in advanced complementary metal–oxide-semiconductor (CMOS) devices
Making of fission 99Mo from LEU silicide(s): A radiochemists' view

International Nuclear Information System (INIS)

Kolar, Z.I.; Wolterbeek, H.Th.

2005-01-01

The present-day industrial scale production of 99 Mo is fission based and involves thermal-neutron irradiation in research reactors of highly enriched uranium (HEU, > 20 % 235 U) containing targets, followed by radiochemical processing of the irradiated targets resulting in the final product: a 99 Mo containing chemical compound of molybdenum. In 1978 a program (RERTR) was started to develop a substitute for HEU reactor fuel i.e. a low enriched uranium (LEU, 235 U) one. In the wake of that program studies were undertaken to convert HEU into LEU based 99 Mo production. Both new targets and radiochemical treatments leading to 99 Mo compounds were proposed. One of these targets is based on LEU silicide, U 3 Si 2 . Present paper aims at comparing LEU U 3 Si 2 and LEU U 3 Si with another LEU target i.e. target material and arriving at some preferences pertaining to 99 Mo production. (author)

Detailed analysis of uranium silicide dispersion fuel swelling

International Nuclear Information System (INIS)

Hofman, G.L.; Ryu, Woo-Seog.

1989-01-01

Swelling of U 3 Si and U 3 Si 2 is analyzed. The growth of fission gas bubbles appears to be affected by fission rate, fuel loading, and microstructural change taking place in the fuel compounds during irradiation. Several mechanisms are explored to explain the observations. The present work is aimed at a better understanding of the basic swelling phenomenon in order to accurately model irradiation behavior of uranium silicide disperson fuel. 5 refs., 10 figs
Enhancement of low temperature toughness of nanoprecipitates strengthened ferritic steel by delamination structure

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yu; Xu, Songsong; Li, Junpeng; Zhang, Jian [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, P R China (China); Sun, Liangwei; Chen, Liang; Sun, Guangai; Peng, Shuming [Key Laboratory of Neutron Physics and Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics (CAEP), Mianyang 621999 (China); Zhang, Zhongwu, E-mail: zwzhang@hrbeu.edu.cn [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, P R China (China)

2017-04-13

This study investigated the effects of aging and thermomechanical treatments on the microstructure evolution and mechanical properties of a nanoprecipitates strengthened ferritic steel. The toughness of steel at various temperatures was measured carefully and correlated with microstructural features. Tensile tests show that aging can improve the mechanical strength without scarifying the ductility. With high yield strength of ~1000 MPa, excellent low temperature Charpy impact energy more than 300 J at −80 °C can be obtained. The ductile brittle transition temperature (DBTT) is lower than −80 °C. The high strength can be contributed by the nanocluster precipitation as determined by small angle neutron scattering and transmission electron microscopy. The excellent low temperature toughness is attributed to the delamination structure of the steel, which blunts the cracks and restrains the crack propagation.
X-ray photoemission spectromicroscopy of titanium silicide formation in patterned microstructures

Energy Technology Data Exchange (ETDEWEB)

Singh, S.; Solak, H.; Cerrina, F. [Univ. of Wisconsin-Madison, Stoughton, WI (United States)] [and others

1997-04-01

Titanium silicide has the lowest resistivity of all the refractory metal silicides and has good thermal stability as well as excellent compatibility with Al metallization. It is used as an intermediate buffer layer between W vias and the Si substrate to provide good electrical contact in ULSI technology, whose submicron patterned features form the basis of the integrated circuits of today and tomorrow, in the self aligned silicide (salicide) formation process. TiSi{sub 2} exists in two phases: a metastable C49 base-centered orthorhombic phase with specific resistivity of 60-90 {mu}{Omega}-cm that is formed at a lower temperature (formation anneal) and the stable 12-15 {mu}{Omega}-cm resistivity face-centered orthorhombic C54 phase into which C49 is transformed with a higher temperature (conversion anneal) step. C54 is clearly the target for low resistivity VLSI interconnects. However, it has been observed that when dimensions shrink below 1/mic (or when the Ti thickness drops below several hundred angstroms), the transformation of C49 into C54 is inhibited and agglomeration often occurs in fine lines at high temperatures. This results in a rise in resistivity due to incomplete transformation to C54 and because of discontinuities in the interconnect line resulting from agglomeration. Spectromicroscopy is an appropriate tool to study the evolution of the TiSi2 formation process because of its high resolution chemical imaging ability which can detect bonding changes even in the absence of changes in the relative amounts of species and because of the capability of studying thick {open_quotes}as is{close_quotes} industrial samples.
X-ray photoemission spectromicroscopy of titanium silicide formation in patterned microstructures

International Nuclear Information System (INIS)

Singh, S.; Solak, H.; Cerrina, F.

1997-01-01

Titanium silicide has the lowest resistivity of all the refractory metal silicides and has good thermal stability as well as excellent compatibility with Al metallization. It is used as an intermediate buffer layer between W vias and the Si substrate to provide good electrical contact in ULSI technology, whose submicron patterned features form the basis of the integrated circuits of today and tomorrow, in the self aligned silicide (salicide) formation process. TiSi 2 exists in two phases: a metastable C49 base-centered orthorhombic phase with specific resistivity of 60-90 μΩ-cm that is formed at a lower temperature (formation anneal) and the stable 12-15 μΩ-cm resistivity face-centered orthorhombic C54 phase into which C49 is transformed with a higher temperature (conversion anneal) step. C54 is clearly the target for low resistivity VLSI interconnects. However, it has been observed that when dimensions shrink below 1/mic (or when the Ti thickness drops below several hundred angstroms), the transformation of C49 into C54 is inhibited and agglomeration often occurs in fine lines at high temperatures. This results in a rise in resistivity due to incomplete transformation to C54 and because of discontinuities in the interconnect line resulting from agglomeration. Spectromicroscopy is an appropriate tool to study the evolution of the TiSi2 formation process because of its high resolution chemical imaging ability which can detect bonding changes even in the absence of changes in the relative amounts of species and because of the capability of studying thick open-quotes as isclose quotes industrial samples
Electron microscopy study of Nb-rich nanoprecipitates in Ni–Ti–Nb and their influence on the martensitic transformation

International Nuclear Information System (INIS)

Shi, H.; Pourbabak, S.; Van Humbeeck, J.; Schryvers, D.

2012-01-01

Graphical abstract: -- Nb-rich nanoprecipitates in the matrix of an annealed commercial Ni–Ti–Nb alloy are investigated by scanning and transmission electron microscopy, including slice-and-view and chemical analysis. The precipitates have a diameter of around 100 nm, are faceted and have a cube-on-cube relation with the B2 matrix. In situ TEM cooling shows that the martensitic transformation is hampered by the presence of these precipitates. The latter could explain the increase in hysteresis when compared with the binary system.
Rare earth silicide nanowires on silicon surfaces

International Nuclear Information System (INIS)

Wanke, Martina

2008-01-01

The growth, structure and electronic properties of rare earth silicide nanowires are investigated on planar and vicinal Si(001) und Si(111) surfaces with scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and angle-resolved photoelectron spectroscopy (ARPES). On all surfaces investigated within this work hexagonal disilicides are grown epitaxially with a lattice mismatch of -2.55% up to +0.83% along the hexagonal a-axis. Along the hexagonal c-axis the lattice mismatch is essentially larger with 6.5%. On the Si(001)2 x 1 surface two types of nanowires are grown epitaxially. The socalled broad wires show a one-dimensional metallic valence band structure with states crossing the Fermi level. Along the nanowires two strongly dispersing states at the anti J point and a strongly dispersing state at the anti Γ point can be observed. Along the thin nanowires dispersing states could not be observed. Merely in the direction perpendicular to the wires an intensity variation could be observed, which corresponds to the observed spacial structure of the thin nanowires. The electronic properties of the broad erbium silicide nanowires are very similar to the broad dysprosium silicide nanowires. The electronic properties of the DySi 2 -monolayer and the Dy 3 Si 5 -multilayer on the Si(111) surface are investigated in comparison to the known ErSi 2 /Si(111) and Er 3 Si 5 /Si(111) system. The positions and the energetic locations of the observed band in the surface Brillouin zone will be confirmed for dysprosium. The shape of the electron pockets in the vector k parallel space is elliptical at the anti M points, while the hole pocket at the anti Γ point is showing a hexagonal symmetry. On the Si(557) surface the structural and electronic properties depend strongly on the different preparation conditions likewise, in particular on the rare earth coverage. At submonolayer coverage the thin nanowires grow in wide areas of the sample surface, which are oriented
Effect of nanoprecipitation and emulsion in polymeric matrices of Polycaprolactone to pharmaceutical applications

International Nuclear Information System (INIS)

Tavares, Marina R.; Menezes, Livia R.; Souza, Diego H.S.; Tavares, Maria Ines B.

2015-01-01

The development of controlled drug delivery systems (DDS) using polymers has been growing on the last years. Polymers used to obtain DDS to the central nervous system (CNS) must be biodegradable and biocompatible. In this context, Polycaprolactone (PCL) is a promising polymer because, besides it presents both characteristics, PCL is also slowly degraded in vivo into non-toxic products and it can last for months. This slow degradation can be a problem to the development of DDS to CNS as it requires that the polymer must present a short biodegradability, not to accumulate. In this study, systems with different PCL concentrations (30, 50 and 75 mg) were prepared by nanoprecipitation and emulsion, and were evaluated by XDR, TGA, FTIR and NMR. We can observe that there was a reduction in PCL crystallinity and an alteration on its crystal peaks positions. (author)
Aqueous PCDTBT:PC71 BM Photovoltaic Inks Made by Nanoprecipitation.

Science.gov (United States)

Prunet, Geoffrey; Parrenin, Laurie; Pavlopoulou, Eleni; Pecastaings, Gilles; Brochon, Cyril; Hadziioannou, Georges; Cloutet, Eric

2018-01-01

The fabrication of organic solar cells from aqueous dispersions of photoactive nanoparticles has recently attracted the interest of the photovoltaic community, since these dispersions offer an eco-friendly solution for the fabrication of solar cells, avoiding the use of toxic solvents. In this work, aqueous dispersions of pure poly[n-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) nanoparticles, as well as of composite PC 71 BM:PCDTBT nanoparticles, are prepared using the nanoprecipitation postpolymerization method. These dispersions are subsequently used to form the active layer of organic photovoltaic cells. Thin films of PC 71 BM and PCDTBT are obtained by spray deposition of the nanoparticles' dispersions, and are characterized using a combination of spectroscopic and microscopic techniques. Photovoltaics that incorporate these active layers are fabricated thereafter. The impact of the annealing temperature and of the composition of the active layer on the efficiency of the solar cells is studied. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Characterization of amylose nanoparticles prepared via nanoprecipitation: Influence of chain length distribution.

Science.gov (United States)

Chang, Yanjiao; Yang, Jingde; Ren, Lili; Zhou, Jiang

2018-08-15

The influence of chain length distribution of amylose on size and structure of the amylose nanoparticles (ANPs) prepared through nanoprecipitation was investigated. Amylose with different chain length distributions was obtained by β-amylase treating amylose paste for different times and measured by size exclusion chromatography (SEC) and fluorophore-assisted carbohydrate electrophoresis (FACE). ANPs prepared via precipitation were characterized by using dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results showed that the β-amylase treatments led to decrease in chain length of amylose, and it was the most important factor affecting size of ANPs. When hydrolysis degree of amylose was 52.8%, mean size of ANPs decreased from 206.4 nm to 102.7 nm. All the ANPs displayed a V-type crystalline structure and the effect of amylose chain length on crystallinity of the precipitated ANPs was negligible in the investigated range. Copyright © 2018 Elsevier Ltd. All rights reserved.
Oxidation-resistant Ge-doped silicide coating on Cr-Cr2Nb alloys by pack cementation

International Nuclear Information System (INIS)

He Yirong

1997-01-01

The halide-activated pack cementation process was modified to produce a Ge-doped silicide diffusion coating on Cr-Cr 2 Nb alloys in a single processing step. The morphology and composition of the coating depended both on the pack composition and processing schedule and also on the composition and microstructure of the substrate. Higher Ge content in the pack suppressed the formation of CrSi 2 and reduced the growth kinetics of the coating. Ge was not homogeneously distributed in the coatings. Under cyclic and isothermal oxidation conditions, the Ge-doped silicide coating protected the Cr-Nb alloys from significant oxidation and from pesting by the formation of a Ge-doped silica film. (orig.)
RA-3 reactor core with uranium silicide fuel elements P-07 type

International Nuclear Information System (INIS)

Abbate, Maximo J.; Sbaffoni, Maria M.

2003-01-01

Following the studies on the utilization of fuel elements (FE) containing uranium silicide, core of the RA-3 was analyzed with several calculation models. At first, the present situation, i.e. the core charged with normal FE (U 3 O 8 ), has been analyzed to validate the simulation methodology comparing with experimental results and to establish reference data to 5 and 10 MW able to be compared with future new situations. Also, CITVAP's nuclear data libraries to be used in irradiation experiment planning were completed. The results were satisfactory and were applied to the study of the core containing P-07 FE [U 3 Si 2 ], in face of a future core change. Comparing with the performance of the U 3 O 8 FE, the silicides ones show the following advantages: - average burnup: 45 % greater; -extraction burnup increase 12 %; and, -the residence time [in full power days] could be a 117 % greater. (author)
X-ray-emission studies of chemical bonding in transition-metal silicides

NARCIS (Netherlands)

Weijs, P.J.W.; Leuken, H. van; Groot, R.A. de; Fuggle, J.C.; Reiter, S.; Wiech, G.; Buschow, K.H.J.

1991-01-01

We present Si L2,3 emission-band spectra of a series of 3d and 4d transition-metal (TM) silicides, together wtih Si K emission-band spectra of four 3d TM disilicides. The data are compared with augmented-spherical-wave density-of-states (DOS) calculations, and good agreement is found. The trends we
High pressure studies on uranium and thorium silicide compounds: Experiment and theory

DEFF Research Database (Denmark)

Yagoubi, S.; Heathman, S.; Svane, A.

2013-01-01

The actinide silicides ThSi, USi and USi2 have been studied under high pressure using both theory and experiment. High pressure synchrotron X-ray diffraction experiments were performed on polycrystalline samples in diamond anvil cells at room temperature and for pressures up to 54, 52 and 26 GPa...
The fabrication and performance of Canadian silicide dispersion fuel for test reactors

International Nuclear Information System (INIS)

Sears, D.F.; Wood, J.C.; Berthiaume, L.C.; Herbert, L.N.; Schaefer, J.D.

1985-01-01

Fuel fabrication effort is now concentrated on the commissioning of large-scale process equipment, defining product specifications, developing a quality assurance plan, and setting up a mini-computer material accountancy system. In the irradiation testing program, full-size NRU assemblies containing 20% enriched silicide dispersion fuel have been Irradiated successfully to burnups in the range 65-80 atomic percent. Irradiations have also been conducted on mini-elements having 1.2 mm diameter holes In their mid-sections, some drilled before irradiation and others after irradiation to 22-83 atomic percent burnup. Uranium was lost to the coolant in direct proportion to the surface area of exposed core material. Pre-irradiation in the intact condition appeared to reduce in-reactor corrosion. Fuel cores developed for the NRU reactor are dimensionally very stable, swelling by only 6-8% at the very high burnup of 93 atomic percent. Two important factors contributing to this good performance are cylindrical clad restraint and coarse silicide particles. Thermal ramping tests were conducted on irradiated silicide aspersion fuels. Small segments of fuel cores released 85 Kr starting at about 520 deg. C and peaking at about 680 deg C. After a holding period of 1 hour at 720 deg. C a secondary 85 Kr peak occurred during cooling (at about 330 deg. C) probably due to thermal contraction cracking. Whole mini-elements irradiated to 93 atomic percent burnup were also ramped thermally, with encouraging results. After about 0.25 h at 530 deg. C the aluminum cladding developed very localized small blisters, some with penetrating pin-hole cracks preventing gross pillowing or ballooning. (author)
The fabrication and performance of Canadian silicide dispersion fuel for test reactors

Energy Technology Data Exchange (ETDEWEB)

Sears, D F; Wood, J C; Berthiaume, L C; Herbert, L N; Schaefer, J D

1985-07-01

Fuel fabrication effort is now concentrated on the commissioning of large-scale process equipment, defining product specifications, developing a quality assurance plan, and setting up a mini-computer material accountancy system. In the irradiation testing program, full-size NRU assemblies containing 20% enriched silicide dispersion fuel have been Irradiated successfully to burnups in the range 65-80 atomic percent. Irradiations have also been conducted on mini-elements having 1.2 mm diameter holes In their mid-sections, some drilled before irradiation and others after irradiation to 22-83 atomic percent burnup. Uranium was lost to the coolant in direct proportion to the surface area of exposed core material. Pre-irradiation in the intact condition appeared to reduce in-reactor corrosion. Fuel cores developed for the NRU reactor are dimensionally very stable, swelling by only 6-8% at the very high burnup of 93 atomic percent. Two important factors contributing to this good performance are cylindrical clad restraint and coarse silicide particles. Thermal ramping tests were conducted on irradiated silicide aspersion fuels. Small segments of fuel cores released {sup 85}Kr starting at about 520 deg. C and peaking at about 680 deg C. After a holding period of 1 hour at 720 deg. C a secondary {sup 85}Kr peak occurred during cooling (at about 330 deg. C) probably due to thermal contraction cracking. Whole mini-elements irradiated to 93 atomic percent burnup were also ramped thermally, with encouraging results. After about 0.25 h at 530 deg. C the aluminum cladding developed very localized small blisters, some with penetrating pin-hole cracks preventing gross pillowing or ballooning. (author)
Rare earth silicide nanowires on silicon surfaces

Energy Technology Data Exchange (ETDEWEB)

Wanke, Martina

2008-11-10

The growth, structure and electronic properties of rare earth silicide nanowires are investigated on planar and vicinal Si(001) und Si(111) surfaces with scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and angle-resolved photoelectron spectroscopy (ARPES). On all surfaces investigated within this work hexagonal disilicides are grown epitaxially with a lattice mismatch of -2.55% up to +0.83% along the hexagonal a-axis. Along the hexagonal c-axis the lattice mismatch is essentially larger with 6.5%. On the Si(001)2 x 1 surface two types of nanowires are grown epitaxially. The socalled broad wires show a one-dimensional metallic valence band structure with states crossing the Fermi level. Along the nanowires two strongly dispersing states at the anti J point and a strongly dispersing state at the anti {gamma} point can be observed. Along the thin nanowires dispersing states could not be observed. Merely in the direction perpendicular to the wires an intensity variation could be observed, which corresponds to the observed spacial structure of the thin nanowires. The electronic properties of the broad erbium silicide nanowires are very similar to the broad dysprosium silicide nanowires. The electronic properties of the DySi{sub 2}-monolayer and the Dy{sub 3}Si{sub 5}-multilayer on the Si(111) surface are investigated in comparison to the known ErSi{sub 2}/Si(111) and Er{sub 3}Si{sub 5}/Si(111) system. The positions and the energetic locations of the observed band in the surface Brillouin zone will be confirmed for dysprosium. The shape of the electron pockets in the (vector)k {sub parallel} space is elliptical at the anti M points, while the hole pocket at the anti {gamma} point is showing a hexagonal symmetry. On the Si(557) surface the structural and electronic properties depend strongly on the different preparation conditions likewise, in particular on the rare earth coverage. At submonolayer coverage the thin nanowires grow in wide areas
Reactivity And Neutron Flux At Silicide Fuel Element In The Core Of RSG-GAS

International Nuclear Information System (INIS)

Hamzah, Amir

2000-01-01

In order to 4.8 and 5.2 gr U/cm exp 3 loading of U 3 Si 2 --Al fuel plates characterization, he core reactivity change and neutron flux depression had been done. Control rod calibration method was used to reactivity change measurement and neutron flux distribution was measured using foil activation method. Measurement of insertion of A-type of testing fuel element with U-loading above cannot be done due to technical reason, so the measurement using full type silicide fuel element of 2.96 gr U/cm exp 3 loading. The reactivity change measurement result of insertion in A-9 and C-3 is + 2.67 cent. The flux depression at silicide fuel in A-9 is 1.69 times bigger than oxide and in C-3 is 0.68 times lower than oxide
A long-term ultrahigh temperature application of layered silicide coated Nb alloy in air

Science.gov (United States)

Sun, Jia; Fu, Qian-Gang; Li, Tao; Wang, Chen; Huo, Cai-Xia; Zhou, Hong; Yang, Guan-Jun; Sun, Le

2018-05-01

Nb-based alloy possessed limited application service life at ultrahigh temperature (>1400 °C) in air even taking the effective protective coating strategy into consideration for last decades. In this work a long duration of above 128 h at 1500 °C in air was successfully achieved on Nb-based alloy thanked to multi-layered silicide coating. Through optimizing interfaces, the MoSi2/NbSi2 silicide coating with Al2O3-adsorbed-particles layer exhibited three-times higher of oxidation resistance capacity than the one without it. In MoSi2-Al2O3-NbSi2 multilayer coating, the Al2O3-adsorbed-particles layer playing as an element-diffusion barrier role, as well as the formed porous Nb5Si3 layer as a stress transition zone, contributed to the significant improvement.
Electrical and optical properties of sub-10 nm nickel silicide films for silicon solar cells

International Nuclear Information System (INIS)

Brahmi, Hatem; Ravipati, Srikanth; Yarali, Milad; Wang, Weijie; Ryou, Jae-Hyun; Mavrokefalos, Anastassios; Shervin, Shahab

2017-01-01

Highly conductive and transparent films of ultra-thin p-type nickel silicide films have been prepared by RF magnetron sputtering of nickel on silicon substrates followed by rapid thermal annealing in an inert environment in the temperature range 400–600 °C. The films are uniform throughout the wafer with thicknesses in the range of 3–6 nm. The electrical and optical properties are presented for nickel silicide films with varying thickness. The Drude–Lorentz model and Fresnel equations were used to calculate the dielectric properties, sheet resistance, absorption and transmission of the films. These ultrathin nickel silicide films have excellent optoelectronic properties for p-type contacts with optical transparencies up to 80% and sheet resistance as low as ∼0.15 µΩ cm. Furthermore, it was shown that the use of a simple anti-reflection (AR) coating can recover most of the reflected light approaching the values of a standard Si solar cell with the same AR coating. Overall, the combination of ultra-low thickness, high transmittance, low sheet resistance and ability to recover the reflected light by utilizing standard AR coating makes them ideal for utilization in silicon based photovoltaic technologies as a p-type transparent conductor. (paper)
Electrical and optical properties of sub-10 nm nickel silicide films for silicon solar cells

Science.gov (United States)

Brahmi, Hatem; Ravipati, Srikanth; Yarali, Milad; Shervin, Shahab; Wang, Weijie; Ryou, Jae-Hyun; Mavrokefalos, Anastassios

2017-01-01

Highly conductive and transparent films of ultra-thin p-type nickel silicide films have been prepared by RF magnetron sputtering of nickel on silicon substrates followed by rapid thermal annealing in an inert environment in the temperature range 400-600 °C. The films are uniform throughout the wafer with thicknesses in the range of 3-6 nm. The electrical and optical properties are presented for nickel silicide films with varying thickness. The Drude-Lorentz model and Fresnel equations were used to calculate the dielectric properties, sheet resistance, absorption and transmission of the films. These ultrathin nickel silicide films have excellent optoelectronic properties for p-type contacts with optical transparencies up to 80% and sheet resistance as low as ~0.15 µΩ cm. Furthermore, it was shown that the use of a simple anti-reflection (AR) coating can recover most of the reflected light approaching the values of a standard Si solar cell with the same AR coating. Overall, the combination of ultra-low thickness, high transmittance, low sheet resistance and ability to recover the reflected light by utilizing standard AR coating makes them ideal for utilization in silicon based photovoltaic technologies as a p-type transparent conductor.

Flash NanoPrecipitation (FNP) for bioengineering nanoparticles to enhance the bioavailability

Science.gov (United States)

Feng, Jie; Zhang, Yingyue; McManus, Simone; Prud'Homme, Robert

2017-11-01

Nanoparticles for the delivery of therapeutics have been one of the successful areas in biomedical nanotechnology. Nanoparticles improve bioavailability by 1) the higher surface-to-volume ratios, enhancing dissolution rates, and 2) trapping drug molecules in higher energy, amorphous states for a higher solubility. However, conventional direct precipitation to prepare nanoparticles has the issues of low loading and encapsulation efficiency. Here we demonstrate a kinetically controlled and rapid-precipitation process called Flash NanoPrecipitation (FNP), to offer a multi-phase mixing platform for bioengineering nanoparticles. With the designed geometry in the micro-mixer, we can generate nanoparticles with a narrow size distribution, while maintaining high loading and encapsulation efficiency. By controlling the time scales in FNP, we can tune the nanoparticle size and the robustness of the process. Remarkably, the dissolution rates of the nanoparticles are significantly improved compared with crystalline drug powders. Furthermore, we investigate how to recover the drug-loaded nanoparticles from the aqueous dispersions. Regarding the maintenance of the bioavailability, we discuss the advantages and disadvantages of each drying process. These results suggest that FNP offers a versatile and scalable nano-fabrication platform for biomedical engineering.
Flash nano-precipitation of polymer blends: a role for fluid flow?

Science.gov (United States)

Grundy, Lorena; Mason, Lachlan; Chergui, Jalel; Juric, Damir; Craster, Richard V.; Lee, Victoria; Prudhomme, Robert; Priestley, Rodney; Matar, Omar K.

2017-11-01

Porous structures can be formed by the controlled precipitation of polymer blends; ranging from porous matrices, with applications in membrane filtration, to porous nano-particles, with applications in catalysis, targeted drug delivery and emulsion stabilisation. Under a diffusive exchange of solvent for non-solvent, prevailing conditions favour the decomposition of polymer blends into multiple phases. Interestingly, dynamic structures can be `trapped' via vitrification prior to thermodynamic equilibrium. A promising mechanism for large-scale polymer processing is flash nano-precipitation (FNP). FNP particle formation has recently been modelled using spinodal decomposition theory, however the influence of fluid flow on structure formation is yet to be clarified. In this study, we couple a Navier-Stokes equation to a Cahn-Hilliard model of spinodal decomposition. The framework is implemented using Code BLUE, a massively scalable fluid dynamics solver, and applied to flows within confined impinging jet mixers. The present method is valid for a wide range of mixing timescales spanning FNP and conventional immersion precipitation processes. Results aid in the fabrication of nano-scale polymer particles with tuneable internal porosities. EPSRC, UK, MEMPHIS program Grant (EP/K003976/1), RAEng Research Chair (OKM), PETRONAS.
Purification in the interaction between yttria mould and Nb-silicide-based alloy during directional solidification: A novel effect of yttrium

International Nuclear Information System (INIS)

Ma, Limin; Tang, Xiaoxia; Wang, Bin; Jia, Lina; Yuan, Sainan; Zhang, Hu

2012-01-01

Nb-silicide-based alloys were directionally solidified in yttria moulds. As a result of thermal dissociation of yttria, the alloys were slightly contaminated with oxygen, which caused a competitive oxidation between yttrium and hafnium. The addition of 0.15 at.% yttrium reduced the oxygen increment by 42%, because the buoyant inclusions concentrated around the top surface. The yttrium addition caused a significant purification of the interaction between the yttria mould and the Nb-silicide-based alloys during the directional solidification.
Thermoelectric Transport Properties of Cu Nanoprecipitates Embedded Bi2Te2.7Se0.3

Directory of Open Access Journals (Sweden)

Eunsil Lee

2015-01-01

Full Text Available We suggest a simple and scalable synthesis to prepare Cu-Bi2Te2.7Se0.3 (Cu-BTS nanocomposites. By precipitating Cu nanoparticle (NP in colloidal suspension of as-exfoliated BTS, homogeneous mixtures of Cu NP and BTS nanosheet were readily achieved, and then the sintered nanocomposites were fabricated by spark plasma sintering technique using the mixed powder as a raw material. The precipitated Cu NPs in the BTS matrix effectively generated nanograin (BTS and heterointerface (Cu/BTS structures. The maximum ZT of 0.90 at 400 K, which is 15% higher compared to that of pristine BTS, was obtained in 3 vol% Cu-BTS nanocomposite. The enhancement of ZT resulted from improved power factor by carrier filtering effect due to the Cu nanoprecipitates in the BTS matrix.
Thermal expansion and elastic moduli of the silicide based intermetallic alloys Ti5Si3(X) and Nb5Si3

International Nuclear Information System (INIS)

Zhang, L.; Wu, J.

1997-01-01

Silicides are among those potential candidates for high temperature application because of their high melting temperature, low density and good oxidation resistance. Recent interest is focused on molybdenum silicides and titanium silicides. Extensive investigation has been carried out on MoSi 2 , yet comparatively less work was performed on titanium silicides such as Ti 5 Si 3 and Ti 3 and TiSi 2 which are of lower density than MoSi 2 . Fundamental understanding of the titanium silicides' properties for further evaluation their potential for practical application are thus needed. The thermal expansion coefficients and elastic moduli of intermetallic compounds are two properties important for evaluation as a first step. The thermal expansion determines the possible stress that might arise during cooling for these high melting point compounds, which is crucial to the preparation of defect free specimens; and the elastic moduli are usually reflections of the cohesion in crystal. In Frommeyer's work and some works afterwards, the coefficients of thermal expansion were measured on both polycrystalline and single crystal Ti 5 Si 3 . The elastic modulus of polycrystalline Ti 5 Si 3 was measured by Frommeyer and Rosenkranz. However, in the above works, the referred Ti 5 Si 3 was the binary one, no alloying effect has been reported on this matter. Moreover, the above parameters (coefficient of thermal expansion and elastic modulus) of Nb 5 Si 3 remain unreported so far. In this paper, the authors try to extend the knowledge of alloyed Ti 5 Si 3 compounds with Nb and Cr additions. Results on the coefficients of thermal expansion and elastic moduli of Ti 5 Si 3 compounds and Nb 5 Si 3 are presented and the discussion is focused on the alloying effect
Core-hole effects in the x-ray-absorption spectra of transition-metal silicides

NARCIS (Netherlands)

WEIJS, PJW; CZYZYK, MT; VANACKER, JF; SPEIER, W; GOEDKOOP, JB; VANLEUKEN, H; HENDRIX, HJM; DEGROOT, RA; VANDERLAAN, G; BUSCHOW, KHJ; WIECH, G; FUGGLE, JC

1990-01-01

We report systematic differences between the shape of the Si K x-ray-absorption spectra of transition-metal silicides and broadened partial densities of Si p states. We use a variety of calculations to show that the origin of these discrepancies is the core-hole potential appropriate to the final
A Study on Characterization of Light-Induced Electroless Plated Ni Seed Layer and Silicide Formation for Solar Cell Application

Science.gov (United States)

Takaloo, Ashkan Vakilipour; Joo, Seung Ki; Es, Firat; Turan, Rasit; Lee, Doo Won

2018-03-01

Light-induced electroless plating (LIEP) is an easy and inexpensive method that has been widely used for seed layer deposition of Nickel/Copper (Ni/Cu)-based metallization in the solar cell. In this study, material characterization aspects of the Ni seed layer and Ni silicide formation at different bath conditions and annealing temperatures on the n-side of a silicon diode structure have been examined to achieve the optimum cell contacts. The effects of morphology and chemical composition of Ni film on its electrical conductivity were evaluated and described by a quantum mechanical model. It has been found that correlation exists between the theoretical and experimental conductivity of Ni film. Residual stress and phase transformation of Ni silicide as a function of annealing temperature were evaluated using Raman and XRD techniques. Finally, transmission line measurement (TLM) technique was employed to determine the contact resistance of Ni/Si stack after thermal treatment and to understand its correlation with the chemical-structural properties. Results indicated that low electrical resistive mono-silicide (NiSi) phase as low as 5 mΩ.cm2 was obtained.
Controlling the formation and stability of ultra-thin nickel silicides - An alloying strategy for preventing agglomeration

Science.gov (United States)

Geenen, F. A.; van Stiphout, K.; Nanakoudis, A.; Bals, S.; Vantomme, A.; Jordan-Sweet, J.; Lavoie, C.; Detavernier, C.

2018-02-01

The electrical contact of the source and drain regions in state-of-the-art CMOS transistors is nowadays facilitated through NiSi, which is often alloyed with Pt in order to avoid morphological agglomeration of the silicide film. However, the solid-state reaction between as-deposited Ni and the Si substrate exhibits a peculiar change for as-deposited Ni films thinner than a critical thickness of tc = 5 nm. Whereas thicker films form polycrystalline NiSi upon annealing above 450 ° C , thinner films form epitaxial NiSi2 films that exhibit a high resistance toward agglomeration. For industrial applications, it is therefore of utmost importance to assess the critical thickness with high certainty and find novel methodologies to either increase or decrease its value, depending on the aimed silicide formation. This paper investigates Ni films between 0 and 15 nm initial thickness by use of "thickness gradients," which provide semi-continuous information on silicide formation and stability as a function of as-deposited layer thickness. The alloying of these Ni layers with 10% Al, Co, Ge, Pd, or Pt renders a significant change in the phase sequence as a function of thickness and dependent on the alloying element. The addition of these ternary impurities therefore changes the critical thickness tc. The results are discussed in the framework of classical nucleation theory.
Study of optical and luminescence properties of silicon — semiconducting silicide — silicon multilayer nanostructures

International Nuclear Information System (INIS)

Galkin, N.G.; Galkin, K.N.; Dotsenko, S.A.; Goroshko, D.L.; Shevlyagin, A.V.; Chusovitin, E.A.; Chernev, I.M.

2017-01-01

By method of in situ differential spectroscopy it was established that at the formation of monolayer Fe, Cr, Ca, Mg silicide and Mg stannide islands on the atomically clean silicon surface an appearance of loss peaks characteristic for these materials in the energy range of 1.1-2.6 eV is observed. An optimization of growth processes permit to grow monolithic double nanoheterostructures (DNHS) with embedded Fe, Cr and Ca nanocrystals, and also polycrystalline DNHS with NC of Mg silicide and Mg stannide and Ca disilicide. By methods of optical spectroscopy and Raman spectroscopy it was shown that embedded NC form intensive peaks in the reflectance spectra at energies up to 2.5 eV and Raman peaks. In DNS with β-FeSi2 NC a photoluminescence and electroluminescence at room temperature were firstly observed.
Role of Ti 3 Al/silicides on tensile properties of Timetal 834 at ...

Indian Academy of Sciences (India)

Extremely fine coherent precipitates of ordered Ti3Al and relatively coarse incoherent precipitates of 2 silicide exist together in the near -titanium alloy, Timetal 834, in the dual phase matrix of primary and transformed . In order to assess the role of these precipitates, three heat treatments viz. WQ, WQ–A and WQ–OA, ...
Prospect of Uranium Silicide fuel element with hypostoichiometric (Si ≤3.7%)

International Nuclear Information System (INIS)

Suripto, A.; Sardjono; Martoyo

1996-01-01

An attempt to obtain high uranium-loading in silicide dispersion fuel element using the fabrication technology applicable nowadays can reach Uranium-loading slightly above 5 gU/cm 3 . It is difficult to achieve a higher uranium-loading than that because of fabricability constraints. To overcome those difficulties, the use of uranium silicide U 3 Si based is considered. The excess of U is obtained by synthesising U 3 Si 2 in Si-hypostoichiometric stage, without applying heat treatment to the ingot as it can generate undesired U 3 Si. The U U will react with the matrix to form U al x compound, that its pressure is tolerable. This experiment is to consider possibilities of employing the U 3 Si 2 as nuclear fuel element which have been performed by synthesising U 3 Si 2 -U with the composition of 3.7 % weigh and 3 % weigh U. The ingot was obtained and converted into powder form which then was fabricated into experimental plate nuclear fuel element. The interaction between free U and Al-matrix during heat-treatment is the rolling phase of the fuel element was observed. The study of the next phase will be conducted later
Neutronic study on conversion of SAFARI-1 to LEU silicide fuel

International Nuclear Information System (INIS)

Ball, G.; Pond, R.; Hanan, N.; Matos, J.

1995-01-01

This paper marks the initial study into the technical and economic feasibility of converting the SAFARI-1 reactor in South Africa to LEU silicide fuel. Several MTR assembly geometries and LEU uranium densities have been studied and compared with MEU and HEU fuels. Two factors of primary importance for conversion of SAFARI-1 to LEU fuel are the economy of the fuel cycle and the performance of the incore and excore irradiation positions
Techno-economic study on conversion of SAFARI-1 to LEU silicide fuel

International Nuclear Information System (INIS)

Ball, G.; Malherbe, F.J.

2004-01-01

This paper marks the conclusion of the techno-economic study into the conversion of SAFARI-1 reactor in South Africa to LEU silicide fuel. Several different fuel types were studied and their characteristics compared to the current HEU fuel. The technical feasibility of operating SAFARI-1 with the different fuels as well as the overall economic impact of the fuels is discussed and conclusions drawn.(author)
Neutronic calculations of PARR-1 cores using LEU silicide fuel

International Nuclear Information System (INIS)

Arshad, M.; Bakhtyar, S.; Hayat, T.; Salahuddin, A.

1991-08-01

Detailed neutronic calculations have been carried out for different PARR-1 cores utilizing low enriched uranium (LEU) silicide fuel and operating at an upgraded power of 9 MW. The calculations include the search for critical loadings in open and stall ends of the pool, neutronic analysis of the first full equilibrium core and calculations cores. The burnup study of inventory have also been carried out. Further, the reactivity coefficients of the first full power operation core are evaluated for use in the accident analysis. 14 figs. (author)
Moissanite (SiC) with metal-silicide and silicon inclusions from tuff of Israel: Raman spectroscopy and electron microscope studies

Science.gov (United States)

Dobrzhinetskaya, Larissa; Mukhin, Pavel; Wang, Qin; Wirth, Richard; O'Bannon, Earl; Zhao, Wenxia; Eppelbaum, Lev; Sokhonchuk, Tatiana

2018-06-01

Here, we present studies of natural SiC that occurs in situ in tuff related to the Miocene alkaline basalt formation deposited in northern part of Israel. Raman spectroscopy, SEM and FIB-assisted TEM studies revealed that SiC is primarily hexagonal polytypes 4H-SiC and 6H-SiC, and that the 4H-SiC polytype is the predominant phase. Both SiC polytypes contain crystalline inclusions of silicon (Sio) and inclusions of metal-silicide with varying compositions (e.g. Si58V25Ti12Cr3Fe2, Si41Fe24Ti20Ni7V5Zr3, and Si43Fe40Ni17). The silicides crystal structure parameters match Si2TiV5 (Pm-3m space group, cubic), FeSi2Ti (Pbam space group, orthorhombic), and FeSi2 (Cmca space group, orthorhombic) respectively. We hypothesize that SiC was formed in a local ultra-reduced environment at respectively shallow depths (60-100 km), through a reaction of SiO2 with highly reducing fluids (H2O-CH4-H2-C2H6) arisen from the mantle "hot spot" and passing through alkaline basalt magma reservoir. SiO2 interacting with the fluids may originate from the walls of the crustal rocks surrounding this magmatic reservoir. This process led to the formation of SiC and accompanied by the reducing of metal-oxides to native metals, alloys, and silicides. The latter were trapped by SiC during its growth. Hence, interplate "hot spot" alkali basalt volcanism can now be included as a geological environment where SiC, silicon, and silicides can be found.
Postirradiation analysis of experimental uranium-silicide dispersion fuel plates

International Nuclear Information System (INIS)

Hofman, G.L.; Neimark, L.A.

1985-01-01

Low-enriched uranium silicide dispersion fuel plates were irradiated to maximum burnups of 96% of 235 U. Fuel plates containing 33 v/o U 3 Si and U 3 Si 2 behaved very well up to this burnup. Plates containing 33 v/o U 3 Si-Al pillowed between 90 and 96% burnup of the fissile atoms. More highly loaded U 3 Si-Al plates, up to 50 v/o were found to pillow at lower burnups. Plates containing 40 v/o U 3 Si showed an increase swelling rate around 85% burnup. 5 refs., 10 figs
Impact of Nickel silicide Rear Metallization on Series Resistance of Crystalline Silicon Solar Cells

KAUST Repository

Bahabry, Rabab R; Hanna, Amir N; Kutbee, Arwa T; Gumus, Abdurrahman; Hussain, Muhammad Mustafa

2018-01-01

the electrical characteristics of nickel mono-silicide (NiSi)/Cu-Al ohmic contact on the rear side of c-Si solar cells. We observe a significant enhancement in the fill factor of around 6.5% for NiSi/Cu-Al rear contacts leading to increasing the efficiency by 1.2
Waste Photovoltaic Panels for Ultrapure Silicon and Hydrogen through the Low-Temperature Magnesium Silicide.

Czech Academy of Sciences Publication Activity Database

Dytrych, Pavel; Bumba, Jakub; Kaštánek, František; Fajgar, Radek; Koštejn, Martin; Šolcová, Olga

Roč. 56, č. 45 ( 2017 ), s. 12863-12869 ISSN 0888-5885 R&D Projects: GA ČR GA15-14228S Institutional support: RVO:67985858 Keywords : magnesium silicide * waste photovoltaic panels * ultrapure silicon Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 2.843, year: 2016
Progress in doping of ruthenium silicide (Ru2Si3)

International Nuclear Information System (INIS)

Vining, C.B.; Allevato, C.E.

1992-01-01

This paper reports that ruthenium silicide (Ru 2 Si 3 ) is currently under development as a promising thermoelectric material suitable for space power applications. Key to realizing the potentially high figure of merit values of this material is the development of appropriate doping techniques. In this study, manganese and iridium have been identified as useful p- and n-type dopants, respectively. Resistivity values have been reduced by more than 3 orders of magnitude. Anomalous Hall effect results, however, complicate interpretation of some of the results and further effort is required to achieve optimum doping levels
Optical metrology of Ni and NiSi thin films used in the self-aligned silicidation process

International Nuclear Information System (INIS)

Kamineni, V. K.; Bersch, E. J.; Diebold, A. C.; Raymond, M.; Doris, B. B.

2010-01-01

The thickness-dependent optical properties of nickel metal and nickel monosilicide (NiSi) thin films, used for self-aligned silicidation process, were characterized using spectroscopic ellipsometry. The thickness-dependent complex dielectric function of nickel metal films is shown to be correlated with the change in Drude free electron relaxation time. The change in relaxation time can be traced to the change in grain boundary (GB) reflection coefficient and grain size. A resistivity based model was used as the complementary method to the thickness-dependent optical model to trace the change in GB reflection coefficient and grain size. After silicidation, the complex dielectric function of NiSi films exhibit non-Drude behavior due to superimposition of interband absorptions arising at lower frequencies. The Optical models of the complete film stack were refined using x-ray photoelectron spectroscopy, Rutherford backscattered spectroscopy, and x-ray reflectivity (XRR).

Fuel element burnup measurements for the equilibrium LEU silicide RSG GAS (MPR-30) core under a new fuel management strategy

International Nuclear Information System (INIS)

Pinem, Surian; Liem, Peng Hong; Sembiring, Tagor Malem; Surbakti, Tukiran

2016-01-01

Highlights: • Burnup measurement of fuel elements comprising the new equilibrium LEU silicide core of RSG GAS. • The burnup measurement method is based on a linear relationship between reactivity and burnup. • Burnup verification was conducted using an in-house, in-core fuel management code BATAN-FUEL. • A good agreement between the measured and calculated burnup was confirmed. • The new fuel management strategy was confirmed and validated. - Abstract: After the equilibrium LEU silicide core of RSG GAS was achieved, there was a strong need to validate the new fuel management strategy by measuring burnup of fuel elements comprising the core. Since the regulatory body had a great concern on the safety limit of the silicide fuel element burnup, amongst the 35 burnt fuel elements we selected 22 fuel elements with high burnup classes i.e. from 20 to 53% loss of U-235 (declared values) for the present measurements. The burnup measurement method was based on a linear relationship between reactivity and burnup where the measurements were conducted under subcritical conditions using two fission counters of the reactor startup channel. The measurement results were compared with the declared burnup evaluated by an in-house in-core fuel management code, BATAN-FUEL. A good agreement between the measured burnup values and the calculated ones was found within 8% uncertainties. Possible major sources of differences were identified, i.e. large statistical errors (i.e. low fission counters’ count rates), variation of initial U-235 loading per fuel element and accuracy of control rod indicators. The measured burnup of the 22 fuel elements provided the confirmation of the core burnup distribution planned for the equilibrium LEU silicide core under the new fuel management strategy.
Understanding and Improving High-Temperature Structural Properties of Metal-Silicide Intermetallics

Energy Technology Data Exchange (ETDEWEB)

Bruce S. Kang

2005-10-10

The objective of this project was to understand and improve high-temperature structural properties of metal-silicide intermetallic alloys. Through research collaboration between the research team at West Virginia University (WVU) and Dr. J.H. Schneibel at Oak Ridge National Laboratory (ORNL), molybdenum silicide alloys were developed at ORNL and evaluated at WVU through atomistic modeling analyses, thermo-mechanical tests, and metallurgical studies. In this study, molybdenum-based alloys were ductilized by dispersing MgAl2O4 or MgO spinel particles. The addition of spinel particles is hypothesized to getter impurities such as oxygen and nitrogen from the alloy matrix with the result of ductility improvement. The introduction of fine dispersions has also been postulated to improve ductility by acting as a dislocation source or reducing dislocation pile-ups at grain boundaries. The spinel particles, on the other hand, can also act as local notches or crack initiation sites, which is detrimental to the alloy mechanical properties. Optimization of material processing condition is important to develop the desirable molybdenum alloys with sufficient room-temperature ductility. Atomistic analyses were conducted to further understand the mechanism of ductility improvement of the molybdenum alloys and the results showed that trace amount of residual oxygen may be responsible for the brittle behavior of the as-cast Mo alloys. For the alloys studied, uniaxial tensile tests were conducted at different loading rates, and at room and elevated temperatures. Thermal cycling effect on the mechanical properties was also studied. Tensile tests for specimens subjected to either ten or twenty thermal cycles were conducted. For each test, a follow-up detailed fractography and microstructural analysis were carried out. The test results were correlated to the size, density, distribution of the spinel particles and processing time. Thermal expansion tests were carried out using thermo
Synthesis of gold nanorod-embedded polymeric nanoparticles by a nanoprecipitation method for use as photothermal agents

Energy Technology Data Exchange (ETDEWEB)

Kim, Eunjung; Choi, Jihye; Haam, Seungjoo [Department of Chemical and Biomolecular Engineering, College of Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Yang, Jaemoon; Suh, Jin-Suck; Huh, Yong-Min, E-mail: ej.kim@yonsei.ac.k, E-mail: 177hum@yonsei.ac.k, E-mail: jjakji2@yonsei.ac.k, E-mail: jss@yuhs.a, E-mail: ymhuh@yuhs.a, E-mail: haam@yonsei.ac.k [Department of Radiology, College of Medicine, Yonsei University, Seoul 120-752 (Korea, Republic of)

2009-09-09

For the synthesis of biocompatible photothermal agents, gold nanorod-embedded polymeric nanoparticles (GPNs) were synthesized using a nanoprecipitation method. Uniform gold nanorods (GNRs), which are sensitive to a photothermal effect by near-infrared (NIR) light, with an aspect ratio of 4.0 were synthesized by a seed-mediated growth method. The hydroxyl groups of polycaprolactone diol (PCL diOH) were modified by esterification with mercaptopropionic acid to give a dithiol (polycaprolactone dithiol, PCL diSH) as a phase transfer and capping agent. Subsequently, hexadecyltrimethylammonium bromide (CTAB), a stabilizer of GNRs, was exchanged and/or removed by PCL diSH. PCL diSH-coated GNRs were further wrapped in a hydrophilic polymer, Pluronic F127, as a stabilizer. These newly formulated GPNs exhibit excellent stability in water and a maximum absorbance in the NIR region indicating a highly efficient surface plasmon resonance effect, phenomena useful for photothermal agents.
Development of molecular dynamics potential for uranium silicide fuels

Energy Technology Data Exchange (ETDEWEB)

Yu, Jianguo; Zhang, Yongfeng; Hales, Jason D.

2016-09-01

Use of uranium–silicide (U-Si) in place of uranium dioxide (UO2) is one of the promising concepts being proposed to increase the accident tolerance of nuclear fuels. This is due to a higher thermal conductivity than UO2 that results in lower centerline temperatures. U-Si also has a higher fissile density, which may enable some new cladding concepts that would otherwise require increased enrichment limits to compensate for their neutronic penalty. However, many critical material properties for U-Si have not been determined experimentally. For example, silicide compounds (U3Si2 and U3Si) are known to become amorphous under irradiation. There was clear independent experimental evidence to support a crystalline to amorphous transformation in those compounds. However, it is still not well understood how the amorphous transformation will affect on fuel behavior. It is anticipated that modeling and simulation may deliver guidance on the importance of various properties and help prioritize experimental work. In order to develop knowledge-based models for use at the engineering scale with a minimum of empirical parameters and increase the predictive capabilities of the developed model, inputs from atomistic simulations are essential. First-principles based density functional theory (DFT) calculations will provide the most reliable information. However, it is probably not possible to obtain kinetic information such as amorphization under irradiation directly from DFT simulations due to size and time limitations. Thus, a more feasible way may be to employ molecular dynamics (MD) simulation. Unfortunately, so far no MD potential is available for U-Si to discover the underlying mechanisms. Here, we will present our recent progress in developing a U-Si potential from ab initio data. This work is supported by the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program funded by the U.S. Department of Energy, Office of Nuclear Energy.
Organometallic Routes into the Nanorealms of Binary Fe-Si Phases

Directory of Open Access Journals (Sweden)

Teddy M. Keller

2010-02-01

Full Text Available The Fe-Si binary system provides several iron silicides that have varied and exceptional material properties with applications in the electronic industry. The well known Fe-Si binary silicides are Fe3Si, Fe5Si3, FeSi, a-FeSi2 and b-FeSi2. While the iron-rich silicides Fe3Si and Fe5Si3 are known to be room temperature ferromagnets, the stoichiometric FeSi is the only known transition metal Kondo insulator. Furthermore, Fe5Si3 has also been demonstrated to exhibit giant magnetoresistance (GMR. The silicon-rich b-FeSi2 is a direct band gap material usable in light emitting diode (LED applications. Typically, these silicides are synthesized by traditional solid-state reactions or by ion beam-induced mixing (IBM of alternating metal and silicon layers. Alternatively, the utilization of organometallic compounds with reactive transition metal (Fe-carbon bonds has opened various routes for the preparation of these silicides and the silicon-stabilized bcc- and fcc-Fe phases contained in the Fe-Si binary phase diagram. The unique interfacial interactions of carbon with the Fe and Si components have resulted in the preferential formation of nanoscale versions of these materials. This review will discuss such reactions.
On the interdiffusion in multilayered silicide coatings for the vanadium-based alloy V-4Cr-4Ti

Energy Technology Data Exchange (ETDEWEB)

Chaia, N., E-mail: nabil.chaia@usp.br [Escola de Engenharia de Lorena, Universidade de São Paulo, Pólo Urbo-Industrial Gleba AI-6, 12602-810 Lorena, SP (Brazil); Portebois, L., E-mail: leo.portebois@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour, UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy, Cedex (France); Mathieu, S., E-mail: stephane.mathieu@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour, UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy, Cedex (France); David, N., E-mail: nicolas.david@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour, UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy, Cedex (France); Vilasi, M., E-mail: michel.vilasi@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour, UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy, Cedex (France)

2017-02-15

To provide protection against corrosion at high temperatures, silicide diffusion coatings were developed for the V-4Cr-4Ti alloy, which can be used as the fuel cladding in next-generation sodium-cooled fast breeder reactors. The multilayered coatings were prepared by halide-activated pack cementation using MgF{sub 2} as the transport agent and pure silicon (high activity) as the master alloy. Coated pure vanadium and coated V-4Cr-4Ti alloy were studied and compared as substrates. In both cases, the growth of the silicide layers (V{sub 3}Si, V{sub 5}Si{sub 3}, V{sub 6}Si{sub 5} and VSi{sub 2}) was controlled exclusively by solid-state diffusion, and the growth kinetics followed a parabolic law. Wagner's analysis was adopted to calculate the integrated diffusion coefficients for all silicides. The estimated values of the integrated diffusion coefficients range from approximately 10{sup −9} to 10{sup −13} cm{sup 2} s{sup −1}. Then, a diffusion-based numerical approach was used to evaluate the growth and consumption of the layers when the coated substrates were exposed at critical temperatures. The estimated lifetimes of the upper VSi{sub 2} layer were 400 h and 280 h for pure vanadium and the V-4Cr-4Ti alloy, respectively. The result from the numeric simulation was in good agreement with the layer thicknesses measured after aging the coated samples at 1150 °C under vacuum. - Highlights: • The pack cementation technique is implemented to study interdiffusion in V/Si and V-4Cr-4Ti/Si couples. • Interdiffusion coefficients of vanadium silicides were experimentally determined within the range 1100–1250 °C. • For either V/Si or V-4Cr-4Ti/Si couples, the VSi{sub 2} layer has the highest growth rate. • The Cr and Ti alloying elements mainly modified the V{sub 5}Si{sub 3} and V{sub 6}Si{sub 5} growth rate. • Numerical simulation allows for a confident assessment of the VSi{sub 2} coating lifetime on V-4Cr-4Ti.
Microstructure of the irradiated U 3Si 2/Al silicide dispersion fuel

Science.gov (United States)

Gan, J.; Keiser, D. D.; Miller, B. D.; Jue, J.-F.; Robinson, A. B.; Madden, J. W.; Medvedev, P. G.; Wachs, D. M.

2011-12-01

The silicide dispersion fuel of U 3Si 2/Al is recognized as the best performance fuel for many nuclear research and test reactors with up to 4.8 gU/cm 3 fuel loading. An irradiated U 3Si 2/Al dispersion fuel ( 235U ˜ 75%) from the high-flux side of a fuel plate (U0R040) from the Reduced Enrichment for Research and Test Reactors (RERTR)-8 test was characterized using transmission electron microscopy (TEM). The fuel was irradiated in the Advanced Test Reactor (ATR) for 105 days. The average irradiation temperature and fission density of the U 3Si 2 fuel particles for the TEM sample are estimated to be approximately 110 °C and 5.4 × 10 27 f/m 3. The characterization was performed using a 200-kV TEM. The U/Si ratio for the fuel particle and (Si + Al)/U for the fuel-matrix-interaction layer are approximately 1.1 and 4-10, respectively. The estimated average diameter, number density and volume fraction for small bubbles (<1 μm) in the fuel particle are ˜94 nm, 1.05 × 10 20 m -3 and ˜11%, respectively. The results and their implication on the performance of the U 3Si 2/Al silicide dispersion fuel are discussed.
Steady-state thermal hydraulic analysis and flow channel blockage accident analysis of JRR-3 silicide core

International Nuclear Information System (INIS)

Kaminaga, Masanori

1997-03-01

JRR-3 is a light water moderated and cooled, beryllium and heavy water reflected pool type research reactor using low enriched uranium (LEU) plate-type fuels. Its thermal power is 20 MW. The core conversion program from uranium-aluminum (UAl x -Al) dispersion type fuel (aluminide fuel) to uranium-silicon-aluminum (U 3 Si 2 -Al) dispersion type fuel (silicide fuel) is currently conducted at the JRR-3. This report describes about the steady-state thermal hydraulic analysis results and the flow channel blockage accident analysis result. In JRR-3, there are two operation mode. One is high power operation mode up to 20 MW, under forced convection cooling using the primary and the secondary cooling systems. The other is low power operation mode up to 200 kW, under natural circulation cooling between the reactor core and the reactor pool without the primary and the secondary cooling systems. For the analysis of the flow channel blockage accident, COOLOD code was used. On the other hand, steady-state thermal hydraulic analysis for both of the high power operation mode under forced convection cooling and low power operation under natural convection cooling, COOLOD-N2 code was used. From steady-state thermal hydraulic analysis results of both forced and natural convection cooling, fuel temperature, minimum DNBR etc. meet the design criteria and JRR-3 LEU silicide core has enough safety margin under normal operation conditions. Furthermore, flow channel blockage accident analysis results show that one channel flow blockage accident meet the safety criteria for accident conditions which have been established for JRR-3 LEU silicide core. (author)
Impact of Nickel silicide Rear Metallization on Series Resistance of Crystalline Silicon Solar Cells

KAUST Repository

Bahabry, Rabab R

2018-01-11

The Silicon-based solar cell is one of the most important enablers toward high efficiency and low-cost clean energy resource. Metallization of silicon-based solar cells typically utilizes screen printed silver-Aluminium (Ag-Al) which affects the optimal electrical performance. To date, metal silicide-based ohmic contacts are occasionally used as an alternative candidate only to the front contact grid lines in crystalline silicon (c-Si) based solar cells. In this paper, we investigate the electrical characteristics of nickel mono-silicide (NiSi)/Cu-Al ohmic contact on the rear side of c-Si solar cells. We observe a significant enhancement in the fill factor of around 6.5% for NiSi/Cu-Al rear contacts leading to increasing the efficiency by 1.2% compared to Ag-Al. This is attributed to the improvement of the parasitic resistance in which the series resistance decreased by 0.737 Ω.cm². Further, we complement experimental observation with a simulation of different contact resistance values, which manifests NiSi/Cu-Al rear contact as a promising low-cost metallization for c-Si solar cells with enhanced efficiency.
High-Temperature Compatible Nickel Silicide Thermometer And Heater For Catalytic Chemical Microreactors

DEFF Research Database (Denmark)

Jensen, Søren; Quaade, U.J.; Hansen, Ole

2005-01-01

Integration of heaters and thermometers is important for agile and accurate control and measurement of the thermal reaction conditions in microfabricated chemical reactors (microreactors). This paper describes development and operation of nickel silicide heaters and temperature sensors...... for temperatures exceeding 700 °C. The heaters and thermometers are integrated with chemical microreactors for heterogeneous catalytic conversion of gasses, and thermally activated catalytic conversion of CO to CO2 in the reactors is demonstrated. The heaters and thermometers are shown to be compatible...
Pilot plant production at Riso of LEU silicide fuel for the Danish reactor DR3

International Nuclear Information System (INIS)

Toft, P.; Borring, J.; Adolph, E.

1988-01-01

A pilot plant for fabricating LEU silicide fuel elements has been established at Riso National Laboratory. Three test elements for the Danish reactor DR3 have been fabricated, based on 19.88% enriched U 3 Si 2 powder that has been purchased elsewhere. The pilot plant has been set up and 3 test elements fabricated without any major difficulties
Numerical modeling of turbulent swirling flow in a multi-inlet vortex nanoprecipitation reactor using dynamic DDES

Science.gov (United States)

Hill, James C.; Liu, Zhenping; Fox, Rodney O.; Passalacqua, Alberto; Olsen, Michael G.

2015-11-01

The multi-inlet vortex reactor (MIVR) has been developed to provide a platform for rapid mixing in the application of flash nanoprecipitation (FNP) for manufacturing functional nanoparticles. Unfortunately, commonly used RANS methods are unable to accurately model this complex swirling flow. Large eddy simulations have also been problematic, as expensive fine grids to accurately model the flow are required. These dilemmas led to the strategy of applying a Delayed Detached Eddy Simulation (DDES) method to the vortex reactor. In the current work, the turbulent swirling flow inside a scaled-up MIVR has been investigated by using a dynamic DDES model. In the DDES model, the eddy viscosity has a form similar to the Smagorinsky sub-grid viscosity in LES and allows the implementation of a dynamic procedure to determine its coefficient. The complex recirculating back flow near the reactor center has been successfully captured by using this dynamic DDES model. Moreover, the simulation results are found to agree with experimental data for mean velocity and Reynolds stresses.
Influence of layout parameters on snapback characteristic for a gate-grounded NMOS device in 0.13-μm silicide CMOS technology

International Nuclear Information System (INIS)

Jiang Yuxi; Li Jiao; Ran Feng; Cao Jialin; Yang Dianxiong

2009-01-01

Gate-grounded NMOS (GGNMOS) devices with different device dimensions and layout floorplans have been designed and fabricated in 0.13-μm silicide CMOS technology. The snapback characteristics of these GGNMOS devices are measured using the transmission line pulsing (TLP) measurement technique. The relationships between snapback parameters and layout parameters are shown and analyzed. A TCAD device simulator is used to explain these relationships. From these results, the circuit designer can predict the behavior of the GGNMOS devices under high ESD current stress, and design area-efficient ESD protection circuits to sustain the required ESD level. Optimized layout rules for ESD protection in 0.13-μm silicide CMOS technology are also presented. (semiconductor devices)
Characterization of tungsten silicides formed by rapid thermal annealing

International Nuclear Information System (INIS)

Siegal, M.; Santiago, J.J.; VanDerSpiegel, J.

1986-01-01

Tungsten silicide samples were formed by sputter depositing 80 nm W metal onto (100) oriented, 5 ohm-cm Si wafers. After deposition, the samples were fast radiatively processed in an RTA system using quartz-halogen tungsten lamps as radiation sources for time intervals ranging from 20 to 60s under high vacuum. Films processed at 22-25 W/cm 2 radiation with the film side of the samples oriented away from the lamps result in films which are metallic or cloudy in color, and have mixed composition as evidenced by x-ray diffraction (W, W 5 Si 3 and WSi 2 ). Films processed with the film side oriented toward the lamps show the occurrence of a phase transformation clearly nucleated at the film edge
In-pile test results of U-silicide or U-nitride coated U-7Mo particle dispersion fuel in Al

Science.gov (United States)

Kim, Yeon Soo; Park, J. M.; Lee, K. H.; Yoo, B. O.; Ryu, H. J.; Ye, B.

2014-11-01

U-silicide or U-nitride coated U-Mo particle dispersion fuel in Al (U-Mo/Al) was in-pile tested to examine the effectiveness of the coating as a diffusion barrier between the U-7Mo fuel kernels and Al matrix. This paper reports the PIE data and analyses focusing on the effectiveness of the coating in terms of interaction layer (IL) growth and general fuel performance. The U-silicide coating showed considerable success, but it also provided evidence for additional improvement for coating process. The U-nitride coated specimen showed largely inefficient results in reducing IL growth. From the test, important observations were also made that can be utilized to improve U-Mo/Al fuel performance. The heating process for coating turned out to be beneficial to suppress fuel swelling. The use of larger fuel particles confirmed favorable effects on fuel performance.
In-pile test results of U-silicide or U-nitride coated U-7Mo particle dispersion fuel in Al

Energy Technology Data Exchange (ETDEWEB)

Kim, Yeon Soo, E-mail: yskim@anl.gov [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Park, J.M.; Lee, K.H.; Yoo, B.O. [Korea Atomic Energy Research Institute, 989-111 Daedeokdaero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Ryu, H.J. [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Ye, B. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

2014-11-15

U-silicide or U-nitride coated U-Mo particle dispersion fuel in Al (U-Mo/Al) was in-pile tested to examine the effectiveness of the coating as a diffusion barrier between the U-7Mo fuel kernels and Al matrix. This paper reports the PIE data and analyses focusing on the effectiveness of the coating in terms of interaction layer (IL) growth and general fuel performance. The U-silicide coating showed considerable success, but it also provided evidence for additional improvement for coating process. The U-nitride coated specimen showed largely inefficient results in reducing IL growth. From the test, important observations were also made that can be utilized to improve U-Mo/Al fuel performance. The heating process for coating turned out to be beneficial to suppress fuel swelling. The use of larger fuel particles confirmed favorable effects on fuel performance.
Excess oxygen limited diffusion and precipitation of iron in amorphous silicon dioxide

Science.gov (United States)

Leveneur, J.; Langlois, M.; Kennedy, J.; Metson, James B.

2017-10-01

In micro- and nano- electronic device fabrication, and particularly 3D designs, the diffusion of a metal into sublayers during annealing needs to be minimized as it is usually detrimental to device performance. Diffusion also causes the formation and growth of nanoprecipitates in solid matrices. In this paper, the diffusion behavior of low energy, low fluence, ion implanted iron into a thermally grown silicon oxide layer on silicon is investigated. Different ion beam analysis and imaging techniques were used. Magnetization measurements were also undertaken to provide evidence of nanocrystalline ordering. While standard vacuum furnace annealing and electron beam annealing lead to fast diffusion of the implanted species towards the Si/SiO2 interface, we show that furnace annealing in an oxygen rich atmosphere prevents the diffusion of iron that, in turn, limits the growth of the nanoparticles. The diffusion and particle growth is also greatly reduced when oxygen atoms are implanted in the SiO2 prior to Fe implantation, effectively acting as a diffusion barrier. The excess oxygen is hypothesized to trap Fe atoms and reduce their mean free path during the diffusion. Monte-Carlo simulations of the diffusion process which consider the random walk of Fe, Fick's diffusion of O atoms, Fe precipitation, and desorption of the SiO2 layer under the electron beam annealing were performed. Simulation results for the three preparation conditions are found in good agreement with the experimental data.
Silicide induced surface defects in FePt nanoparticle fcc-to-fct thermally activated phase transition

International Nuclear Information System (INIS)

Chen, Shu; Lee, Stephen L.; André, Pascal

2016-01-01

Magnetic nanoparticles (MnPs) are relevant to a wide range of applications including high density information storage and magnetic resonance imaging to name but a few. Among the materials available to prepare MnPs, FePt is attracting growing attention. However, to harvest the strongest magnetic properties of FePt MnPs, a thermal annealing is often required to convert face-centered cubic as synthesized nPs into its tetragonal phase. Rarely addressed are the potential side effects of such treatments on the magnetic properties. In this study, we focus on the impact of silica shells often used in strategies aiming at overcoming MnP coalescence during the thermal annealing. While we show that this shell does prevent sintering, and that fcc-to-fct conversion does occur, we also reveal the formation of silicide, which can prevent the stronger magnetic properties of fct-FePt MnPs from being fully realised. This report therefore sheds lights on poorly investigated and understood interfacial phenomena occurring during the thermal annealing of MnPs and, by doing so, also highlights the benefits of developing new strategies to avoid silicide formation.
Mössbauer spectroscopy study of surfactant sputtering induced Fe silicide formation on a Si surface

Energy Technology Data Exchange (ETDEWEB)

Beckmann, C.; Zhang, K. [2nd Institute of Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany); Hofsäss, H., E-mail: hans.hofsaess@phys.uni-goettingen.de [2nd Institute of Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany); Brüsewitz, C.; Vetter, U. [2nd Institute of Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany); Bharuth-Ram, K. [Physics Department, Durban University of Technology, Durban 4001 (South Africa)

2015-12-01

Highlights: • We study the formation of self-organized nanoscale dot and ripple patterns on Si. • Patterns are created by keV noble gas ion irradiation and simultaneous {sup 57}Fe co-deposition. • Ion-induced phase separation and the formation of a-FeSi{sub 2} is identified as relevant process. - Abstract: The formation of Fe silicides in surface ripple patterns, generated by erosion of a Si surface with keV Ar and Xe ions and simultaneous co-deposition of Fe, was investigated with conversion electron Mössbauer spectroscopy, atomic force microscopy and Rutherford backscattering spectrometry. For the dot and ripple patterns studied, we find an average Fe concentration in the irradiated layer between 6 and 25 at.%. The Mössbauer spectra clearly show evidence of the formation of Fe disilicides with Fe content close to 33 at.%, but very little evidence of the formation of metallic Fe particles. The results support the process of ion-induced phase separation toward an amorphous Fe disilicide phase as pattern generation mechanism. The observed amorphous phase is in agreement with thermodynamic calculations of amorphous Fe silicides.
Silicide induced surface defects in FePt nanoparticle fcc-to-fct thermally activated phase transition

Energy Technology Data Exchange (ETDEWEB)

Chen, Shu; Lee, Stephen L. [School of Physics and Astronomy, SUPA, University of St Andrews, St Andrews KY16 9SS (United Kingdom); André, Pascal, E-mail: pjpandre@riken.jp [School of Physics and Astronomy, SUPA, University of St Andrews, St Andrews KY16 9SS (United Kingdom); RIKEN, Wako 351-0198 (Japan); Department of Physics, CNRS-Ewha International Research Center (CERC), Ewha W. University, Seoul 120-750 (Korea, Republic of)

2016-11-01

Magnetic nanoparticles (MnPs) are relevant to a wide range of applications including high density information storage and magnetic resonance imaging to name but a few. Among the materials available to prepare MnPs, FePt is attracting growing attention. However, to harvest the strongest magnetic properties of FePt MnPs, a thermal annealing is often required to convert face-centered cubic as synthesized nPs into its tetragonal phase. Rarely addressed are the potential side effects of such treatments on the magnetic properties. In this study, we focus on the impact of silica shells often used in strategies aiming at overcoming MnP coalescence during the thermal annealing. While we show that this shell does prevent sintering, and that fcc-to-fct conversion does occur, we also reveal the formation of silicide, which can prevent the stronger magnetic properties of fct-FePt MnPs from being fully realised. This report therefore sheds lights on poorly investigated and understood interfacial phenomena occurring during the thermal annealing of MnPs and, by doing so, also highlights the benefits of developing new strategies to avoid silicide formation.

Magnesium and Manganese Silicides For Efficient And Low Cost Thermo-Electric Power Generation

Energy Technology Data Exchange (ETDEWEB)

Trivedi, Sudhir B. [Brimrose Technology Corporation; Kutcher, Susan W. [Brimrose Technology Corporation; Rosemeier, Cory A. [Brimrose Technology Corporation; Mayers, David [Brimrose Technology Corporation; Singh, Jogender [Pennsylvania State University

2013-12-02

Thermoelectric Power Generation (TEPG) is the most efficient and commercially deployable power generation technology for harvesting wasted heat from such things as automobile exhausts, industrial furnaces, and incinerators, and converting it into usable electrical power. We investigated the materials magnesium silicide (Mg2Si) and manganese silicide (MnSi) for TEG. MgSi2 and MnSi are environmentally friendly, have constituent elements that are abundant in the earth's crust, non-toxic, lighter and cheaper. In Phase I, we successfully produced Mg2Si and MnSi material with good TE properties. We developed a novel technique to synthesize Mg2Si with good crystalline quality, which is normally very difficult due to high Mg vapor pressure and its corrosive nature. We produced n-type Mg2Si and p-type MnSi nanocomposite pellets using FAST. Measurements of resistivity and voltage under a temperature gradient indicated a Seebeck coefficient of roughly 120 V/K on average per leg, which is quite respectable. Results indicated however, that issues related to bonding resulted in high resistivity contacts. Determining a bonding process and bonding material that can provide ohmic contact from room temperature to the operating temperature is an essential part of successful device fabrication. Work continues in the development of a process for reproducibly obtaining low resistance electrical contacts.
Electron spectroscopy in the X-ray range for occupied and free levels and the application to transition metal silicides

International Nuclear Information System (INIS)

Speier, W.

1988-03-01

Intermetallic compounds of transition metals are investigated by means of XPS, Bremsstrahlung Isochromate Spectroscopy and XAS. Occupied and free levels are characterized and moreover a systematic overview over the electronic structure of the transition element silicides is given. (BHO)
The role of nitrogen in luminescent Si nanoprecipitate formation during annealing of Si ion-implanted SiO sub 2 layers

CERN Document Server

Kachurin, G A; Zhuravlev, K S; Ruault, M O

2001-01-01

SiO sub 2 layers were implanted with 25 keV Si sup + and 13 keV N sup + ions with the doses of (1-4) x 10 sup 1 sup 6 cm sup - sup 2 and (0.2-2) x 10 sup 1 sup 6 cm sup - sup 2 , respectively. Then the samples were annealed at 900-1100 deg C to form luminescent silicon nanoprecipitates. The nitrogen effect on the process is controlled by photoluminescence spectra. It is found out that the photoluminescence intensity increases considerably at the appropriate ratio between silicon and nitrogen. It has been concluded that the interaction of nitrogen with excessive silicon results in increasing the number of precipitation centers. This raises the nanocrystals number and reduces their mean size
Creation of Y2Ti2O7 nanoprecipitates to strengthen the Fe-14Cr-3Al-2W steels by adding Ti hydride and Y2O3 nanoparticles

International Nuclear Information System (INIS)

Wang, Linbo; Bai, Zhonglian; Shen, Hailong; Wang, Chenxi; Liu, Tong

2017-01-01

In order to prohibit the formation of large Y-Al-O precipitates, Ti hydride nanoparticles (NPs) were prepared and used to replace Ti as raw particles to fabricate the oxide dispersion strengthened (ODS) Fe-14Cr-3Al-2W-0.35Y 2 O 3 steels by mechanical alloying (MA) and hot isostatic pressing (HIP). As the content of Ti hydride increases from 0.1 to 0.5 and 1.0 wt%, the oxide nanoprecipitates in the ODS steels changes from Y 3 Al 5 O 12 phase to Y 2 Ti 2 O 7 phase (semicoherent with the matrix), and the particle size is successfully reduced. The tensile strength of the ODS steel increases remarkably with increasing Ti hydride content. The sample with 1.0 wt% Ti hydride exhibits a high strength of 1049 MPa at 25 °C and 278 MPa at 700 °C. The creation of Y 2 Ti 2 O 7 nanoprecipitates by adding Ti hydride NPs opens a new way to control the structure and size of the oxide precipitates in the ODS steels. - Graphical abstract: The creation of Y 2 Ti 2 O 7 nanoprecipitates by adding Ti hydride nanoparticles remarkably increases the mechanical properties of the Al-containing ODS steels. - Highlights: •TiH 1.971 reacts with Y 2 O 3 to form Y 2 Ti 2 O 7 in the Al-containing ODS steel. •Addition of TiH 1.971 nanoparticles can prevent the formation of Y-Al-O phases. •Y 2 Ti 2 O 7 nanoparticles share semicoherent interface with the ferrite matrix. •The mean size of oxide dispersion is reduced to 11.2 ± 7.1 nm with 1.0 wt% TiH 1.971 . •The tensile strength of the ODS steel enlarges with increasing TiH 1.971 content.
Microstructure and mechanical properties of molybdenum silicides with Al additions

International Nuclear Information System (INIS)

Rosales, I.; Bahena, D.; Colin, J.

2007-01-01

Several molybdenum silicides alloys with different aluminum additions were produced by the arc-cast method. Microstructure observed in the alloys presented a variation of the precipitated second phase respect to the aluminum content. Evaluation of the compressive behavior at high temperature of the alloys shows an important improvement in its ductility, approximately of 20%. Fracture toughness was increased proportionally with Al content. In addition at room temperature the alloys show a better mechanical behavior in comparison with the sample unalloyed. In general, Al additions result to be a good alternative to improve the resistance of these intermetallic alloys. The results are interpreted on the base of the analysis of second phase strengthening
Evaluation of powder metallurgical processing routes for multi-component niobium silicide-based high-temperature alloys

Energy Technology Data Exchange (ETDEWEB)

Seemueller, Hans Christoph Maximilian

2016-03-22

Niobium silicide-based composites are potential candidates to replace nickel-base superalloys for turbine applications. The goal of this work was to evaluate the feasibility and differences in ensuing properties of various powder metallurgical processing techniques that are capable of manufacturing net-shape turbine components. Two routes for powder production, mechanical alloying and gas atomization were combined with compaction via hot isostatic pressing and powder injection molding.
Capacitance-voltage characterization of fully silicided gated MOS capacitor

International Nuclear Information System (INIS)

Wang Baomin; Ru Guoping; Jiang Yulong; Qu Xinping; Li Bingzong; Liu Ran

2009-01-01

This paper investigates the capacitance-voltage (C-V) measurement on fully silicided (FUSI) gated metal-oxide-semiconductor (MOS) capacitors and the applicability of MOS capacitor models. When the oxide leakage current of an MOS capacitor is large, two-element parallel or series model cannot be used to obtain its real C-V characteristic. A three-element model simultaneously consisting of parallel conductance and series resistance or a four-element model with further consideration of a series inductance should be used. We employed the three-element and the four-element models with the help of two-frequency technique to measure the Ni FUSI gated MOS capacitors. The results indicate that the capacitance of the MOS capacitors extracted by the three-element model still shows some frequency dispersion, while that extracted by the four-element model is close to the real capacitance, showing little frequency dispersion. The obtained capacitance can be used to calculate the dielectric thickness with quantum effect correction by NCSU C-V program. We also investigated the influence of MOS capacitor's area on the measurement accuracy. The results indicate that the decrease of capacitor area can reduce the dissipation factor and improve the measurement accuracy. As a result, the frequency dispersion of the measured capacitance is significantly reduced, and real C-V characteristic can be obtained directly by the series model. In addition, this paper investigates the quasi-static C-V measurement and the photonic high-frequency C-V measurement on Ni FUSI metal gated MOS capacitor with a thin leaky oxide. The results indicate that the large tunneling current through the gate oxide significantly perturbs the accurate measurement of the displacement current, which is essential for the quasi-static C-V measurement. On the other hand, the photonic high-frequency C-V measurement can bypass the leakage problem, and get reliable low-frequency C-V characteristic, which can be used to
Hot wire chemical vapor deposition: limits and opportunities of protecting the tungsten catalyzer from silicide with a cavity

International Nuclear Information System (INIS)

Frigeri, P.A.; Nos, O.; Bengoechea, S.; Frevert, C.; Asensi, J.M.; Bertomeu, J.

2009-01-01

Hot Wire Chemical Vapor Deposition (HW-CVD) is one of the most promising techniques for depositing the intrinsic microcrystalline silicon layer for the production of micro-morph solar cells. However, the silicide formation at the colder ends of the tungsten wire drastically reduces the lifetime of the catalyzer, thus limiting its industrial exploitation. A simple but interesting strategy to decrease the silicide formation is to hide the electrical contacts of the catalyzer in a long narrow cavity which reduces the probability of the silane molecules to reach the colder ends of the wire. In this paper, the working mechanism of the cavity is elucidated. Measurements of the thickness profile of the silicon deposited in the internal walls of the cavity have been compared with those predicted using a simple diffusion model based on the assumption of Knudsen flow. A lifetime study of the protected and unprotected wires has been carried out. The different mechanisms which determine the deterioration of the catalyzer have been identified and discussed.
The heat capacity and entropy of the lithium silicides Li17Si4 and Li16.42Si4 in the temperature range from (2 to 873) K

International Nuclear Information System (INIS)

Thomas, Daniel; Zeilinger, Michael; Gruner, Daniel; Hüttl, Regina; Seidel, Jürgen; Wolter, Anja U.B.; Fässler, Thomas F.; Mertens, Florian

2015-01-01

Highlights: • High quality experimental heat capacities of the new lithium rich silicides Li 17 Si 4 and Li 16.42 Si 4 are reported. • Two different calorimeters have been used to cover the broad temperature range from (2 to 873) K. • Samples were prepared and characterized (XRD) by the original authors who firstly described these new silicide phases in 2013. • Supply of polynomial heat capacity functions for four temperature intervals. • Calculation of standard entropies and entropies of formation of the lithium silicides. - Abstract: This work presents the heat capacities and standard entropies of the recently described lithium rich silicide phases Li 17 Si 4 and Li 16.42 Si 4 as a function of temperature in the range from (2 to 873) K. The measurements were carried out using two different calorimeters. The heat capacities were determined in the range from T = (2 to 300) K by a relaxation technique using a Physical Properties Measurement System (PPMS) from Quantum Design, and in the range from T = (283 to 873) K by means of a Sensys DSC from Setaram applying the C p -by-step method. The experimental data are given with an accuracy of (1 to 2)% above T = 20 K and the error increases up to 7% below T = 20 K. The results of the measurements at low temperatures permit the calculation of additional thermodynamic parameters such as the standard entropy as well as the temperature coefficients of electronic and lattice contributions to the heat capacity. Additionally, differential scanning calorimetric (DSC) measurements were carried out to verify the phase transition temperatures of the studied lithium silicide phases. The results represent a significant contribution to the data basis for thermodynamic calculations (e.g. CALPHAD) and to the understanding of the phase equilibria in the (Li + Si) system, especially in the lithium rich region
Analysis Influence of Mixing Gd2O3 in the Silicide Fuel Element to Core Excess Reactivity of RSG-GAS

International Nuclear Information System (INIS)

Susilo, Jati

2004-01-01

Gadolinium (Gd 2 O 3 ) is a burnable poison material mixed in the pin fuel element of the LWR core used to decrease core excess reactivity. In this research, analysis influence of mixing Gd 2 O 3 in the silicide fuel element to excess reactivity of the RSG-GAS core had been done. Equivalent cell of the equilibrium core developed by L.E.Strawbridge from Westing House Co. burn-up calculation has been done using SRAC-PIJ computer code achieve infinite multiplication factor (k x ). Value of Gd 2 O 3 concentration in the fuel element (pcm) showed by mass ratio of Gd 2 O 3 (gram) to that U 3 Si 2 (gram) times 10 5 , that is 0 pcm ∼ 100 pcm. From the calculation results analysis showed that Gd 2 O 3 concentration added should be considered. because a large number of Gd 2 O 3 will result in not achieving criticality at the Beginning Of Cycle. The maximum concentration of Gd 2 O 3 for RSG-GAS equilibrium fueled silicide 2.96 grU/cc is 80 pcm or 52.02 mgram/fuel plate. Maximum reduction of core excess reactivity due to mixing of Gd 2 O 3 in the RSG-GAS silicide fuels was around 1.502 %Δk/k, and hence not achieving the standard nominal excess reactivity for RSG-GAS core using high density of U 3 Si 2 -Al fuel. (author)
Estimations on uranium silicide fuel prototypes for their irradiation and postirradiation

International Nuclear Information System (INIS)

Sbaffoni, Maria M.

2000-01-01

The 'Silicide' project includes the qualification of this type of research reactor fuel to be used i.e. in the Argentine RA-3 and to confirm CNEA's role as an international supplier. The present paper shows complementary basic information for P-04 prototype post-irradiation, which is already under way, and some parameter values related to the new P-06 prototype to be taken into account for planning its irradiation and post-irradiation. The reliability of these values has been evaluated through comparison with experimental results. The reported results contribute, also, to a parallel study on the nuclear data libraries used in calculations for this type of reactor. (author)
Anti-cancer evaluation of quercetin embedded PLA nanoparticles synthesized by emulsified nanoprecipitation.

Science.gov (United States)

Pandey, Sanjeev K; Patel, Dinesh K; Thakur, Ravi; Mishra, Durga P; Maiti, Pralay; Haldar, Chandana

2015-04-01

This study was carried out to synthesize quercetin (Qt) embedded poly(lactic acid) (PLA) nanoparticles (PLA-Qt) and to evaluate anti-cancer efficacy of PLA-Qt by using human breast cancer cells. PLA-Qt were synthesized by using novel emulsified nanoprecipitation technique with varying dimension of 32 ± 8 to 152 ± 9 nm of PLA-Qt with 62 ± 3% (w/w) entrapment efficiency by varying the concentration of polymer, emulsifier, drug and preparation temperature. The dimension of PLA-Qt was measured through transmission electron microscopy indicating larger particle size at higher concentration of PLA. The release rate of Qt from PLA-Qt was found to be more sustained for larger particle dimension (152 ± 9 nm) as compared to smaller particle dimension (32 ± 8 nm). Interaction between Qt and PLA was verified through spectroscopic and calorimetric methods. Delayed diffusion and stronger interaction in PLA-Qt caused the sustained delivery of Qt from the polymer matrix. In vitro cytotoxicity study indicate the killing of ∼ 50% breast cancer cells in two days at 100 μg/ml of drug concentration while the ∼ 40% destruction of cells require 5 days for PLA-Qt (46 ± 6 nm; 20mg/ml of PLA). Thus our results propose anticancer efficacy of PLA-Qt nanoparticles in terms of its sustained release kinetics revealing novel vehicle for the treatment of cancer. Copyright © 2015 Elsevier B.V. All rights reserved.
Intermetallic nickel silicide nanocatalyst-A non-noble metal-based general hydrogenation catalyst.

Science.gov (United States)

Ryabchuk, Pavel; Agostini, Giovanni; Pohl, Marga-Martina; Lund, Henrik; Agapova, Anastasiya; Junge, Henrik; Junge, Kathrin; Beller, Matthias

2018-06-01

Hydrogenation reactions are essential processes in the chemical industry, giving access to a variety of valuable compounds including fine chemicals, agrochemicals, and pharmachemicals. On an industrial scale, hydrogenations are typically performed with precious metal catalysts or with base metal catalysts, such as Raney nickel, which requires special handling due to its pyrophoric nature. We report a stable and highly active intermetallic nickel silicide catalyst that can be used for hydrogenations of a wide range of unsaturated compounds. The catalyst is prepared via a straightforward procedure using SiO 2 as the silicon atom source. The process involves thermal reduction of Si-O bonds in the presence of Ni nanoparticles at temperatures below 1000°C. The presence of silicon as a secondary component in the nickel metal lattice plays the key role in its properties and is of crucial importance for improved catalytic activity. This novel catalyst allows for efficient reduction of nitroarenes, carbonyls, nitriles, N-containing heterocycles, and unsaturated carbon-carbon bonds. Moreover, the reported catalyst can be used for oxidation reactions in the presence of molecular oxygen and is capable of promoting acceptorless dehydrogenation of unsaturated N-containing heterocycles, opening avenues for H 2 storage in organic compounds. The generality of the nickel silicide catalyst is demonstrated in the hydrogenation of over a hundred of structurally diverse unsaturated compounds. The wide application scope and high catalytic activity of this novel catalyst make it a nice alternative to known general hydrogenation catalysts, such as Raney nickel and noble metal-based catalysts.
Surface effect on the electronic and the magnetic properties of rock-salt alkaline-earth metal silicides

International Nuclear Information System (INIS)

Bialek, Beata; Lee, Jaeil

2011-01-01

An all electron ab-initio method was employed to study the electronic and the magnetic properties of the (001) surface of alkaline-earth metal silicides, CaSi, SrSi, and BaSi, in the rock-salt structure. The three compounds retain their ferromagnetic metallic properties at the surface. Due to the surface effects, the magnetism of the topmost layer is changed as compared with the bulk. This is a short-range effect. In CaSi, the magnetism of the surface layer is noticeably reduced, as compared with the bulk: magnetic moments (MMs) on both Ca and Si atoms are reduced. In SrSi (001), the polarization of electrons in the surface atoms is similar to that in the bulk atoms, and the values of MMs on the component atoms in the topmost layer do not change as much as in CaSi. In BaSi (001), the magnetic properties of Si surface atoms are enhanced slightly, and the magnetism of Ba atoms is not affected considerably by the surface effect. The calculated densities of states confirm the short-range effect of the surface on the electronic properties of the metal silicides.
High-temperature oxidation of silicide-aluminide layer on the TiAl6V4 alloy prepared by liquid-phase siliconizing

Czech Academy of Sciences Publication Activity Database

Kubatík, Tomáš František

2016-01-01

Roč. 50, č. 2 (2016), s. 257-261 ISSN 1580-2949 Institutional support: RVO:61389021 Keywords : TiAl6V4 * silicides * high-temperature oxidation * liquid-phase silicon izing Subject RIV: JG - Metallurgy Impact factor: 0.436, year: 2016
Attempt to produce silicide fuel elements in Indonesia

International Nuclear Information System (INIS)

Soentono, S.; Suripto, A.

1991-01-01

After the successful experiment to produce U 3 Si 2 powder and U 3 Si 2 -Al fuel plates using depleted U and Si of semiconductor quality, silicide fuel was synthesized using x -Al available at the Fuel Element Production Installation (FEPI) at Serpong, Indonesia. Two full-size U 3 Si 2 -Al fuel elements, having similar specifications to the ones of U 3 O 8 -Al for the RSG-GAS (formerly known as MPR-30), have been produced at the FEPI. All quality controls required have been imposed to the feeds, intermediate, as well as final products throughout the production processes of the two fuel elements. The current results show that these fuel elements are qualified from fabrication point of view, therefore it is expected that they will be permitted to be tested in the RSG-GAS, sometime by the end of 1989, for normal (∝50%) and above normal burn-up. (orig.)
Preliminary investigations on the use of uranium silicide targets for fission Mo-99 production

Energy Technology Data Exchange (ETDEWEB)

Cols, H.; Cristini, P.; Marques, R.

1997-08-01

The National Atomic Energy Commission (CNEA) of Argentine Republic owns and operates an installation for production of molybdenum-99 from fission products since 1985, and, since 1991, covers the whole national demand of this nuclide, carrying out a program of weekly productions, achieving an average activity of 13 terabecquerel per week. At present they are finishing an enlargement of the production plant that will allow an increase in the volume of production to about one hundred of terabecquerel. Irradiation targets are uranium/aluminium alloy with 90% enriched uranium with aluminium cladding. In view of international trends held at present for replacing high enrichment uranium (HEU) for enrichment values lower than 20 % (LEU), since 1990 the authors are in contact with the RERTR program, beginning with tests to adapt their separation process to new irradiation target conditions. Uranium silicide (U{sub 3}Si{sub 2}) was chosen as the testing material, because it has an uranium mass per volume unit, so that it allows to reduce enrichment to a value of 20%. CNEA has the technology for manufacturing miniplates of uranium silicide for their purposes. In this way, equivalent amounts of Molybdenum-99 could be obtained with no substantial changes in target parameters and irradiation conditions established for the current process with Al/U alloy. This paper shows results achieved on the use of this new target.
Current enhancement in crystalline silicon photovoltaic by low-cost nickel silicide back contact

KAUST Repository

Bahabry, R. R.; Gumus, A.; Kutbee, A. T.; Wehbe, N.; Ahmed, S. M.; Ghoneim, M. T.; Lee, K. -T.; Rogers, J. A.; Hussain, M. M.

2016-01-01

We report short circuit current (Jsc) enhancement in crystalline silicon (C-Si) photovoltaic (PV) using low-cost Ohmic contact engineering by integration of Nickel mono-silicide (NiSi) for back contact metallization as an alternative to the status quo of using expensive screen printed silver (Ag). We show 2.6 mA/cm2 enhancement in the short circuit current (Jsc) and 1.2 % increment in the efficiency by improving the current collection due to the low specific contact resistance of the NiSi on the heavily Boron (B) doped Silicon (Si) interface.
Current enhancement in crystalline silicon photovoltaic by low-cost nickel silicide back contact

KAUST Repository

Bahabry, R. R.

2016-11-30

We report short circuit current (Jsc) enhancement in crystalline silicon (C-Si) photovoltaic (PV) using low-cost Ohmic contact engineering by integration of Nickel mono-silicide (NiSi) for back contact metallization as an alternative to the status quo of using expensive screen printed silver (Ag). We show 2.6 mA/cm2 enhancement in the short circuit current (Jsc) and 1.2 % increment in the efficiency by improving the current collection due to the low specific contact resistance of the NiSi on the heavily Boron (B) doped Silicon (Si) interface.
Temperature and thickness dependence of the grain boundary scattering in the Ni–Si silicide films formed on silicon substrate at 500 °C by RTA

International Nuclear Information System (INIS)

Utlu, G.; Artunç, N.; Selvi, S.

2012-01-01

Highlights: ► It is a systematic study of various thicknesses (18–290 nm) of Ni–Si silicide films. ► The temperature-dependent resistivity measurements of the films are studied. ► Resistivity variation of the films with temperature exhibits an unusual behavior. ► Parallel-resistor formula is reduced to Matthiessen's rule in this study. ► Reflection coefficients have been found in a wide temperature and thickness range. - Abstract: The temperature-dependent resistivity measurements of Ni–Si silicide films with 18–290 nm thicknesses are studied as a function of temperature and film thickness over the temperature range of 100–900 K. The most striking behavior is that the variation of the resistivity of the films with temperature exhibits an unusual behavior. The total resistivity of the Ni–Si silicide films in this work increases linearly with temperature up to a T m temperature, thereafter decreases rapidly and finally reaches zero. Our analyses have shown that in the temperature range of 100 to T m (K), parallel-resistor formula reduces to Matthiessen's rule and θ D Debye temperature becomes independent of the temperature for the given thickness range, whereas at high temperatures (above T m ) it increases slightly with thickness. θ D Debye temperature have been found to be about 400–430 K for the films. We have also shown that for temperature range of 100 to T m (K), linear variation of the resistivity of the silicide films with temperature has been caused from both grain-boundary scattering and electron–phonon scattering. That is why, resistivity data could have been analyzed in terms of the Mayadas–Schatzkes (M–S) model successfully. Theoretical and experimental values of reflection coefficients have been calculated by analyzing resistivity data using M–S model. According to our analysis, R increases with decreasing film thickness for a given temperature, while it is almost constant for the thickness range of 200–67 nm and 47�

Measurements of turbulence in a microscale multi-inlet vortex nanoprecipitation reactor

International Nuclear Information System (INIS)

Shi, Yanxiang; Cheng, Janine Chungyin; Fox, Rodney O; Olsen, Michael G

2013-01-01

The microscale multi-inlet vortex reactor (MIVR) is designed for use in Flash NanoPrecipitation (FNP), a promising technique for producing nanoparticles within small particle size distribution. Fluid mixing is crucial in the FNP process, and due to mixing’s strong dependence upon fluid kinematics, investigating velocity and turbulence within the reactor is crucial to optimizing reactor design. To this end, microscopic particle image velocimetry has been used to investigate flow within the MIVR. Three Reynolds numbers are studied, namely, Re j = 53, 93 and 240. At Re j = 53, the flow is laminar and steady. Due to the strong viscous effects at this Reynolds number, distinct flow patterns are observed at different distances from the reactor top and bottom walls. The viscous effects also retard the tangential motions within the reactor, resulting in a weaker vortex than appears at the higher Reynolds numbers. As the Reynolds number is increased to 93, the flow becomes more homogeneous over the depth of the reactor due to weaker viscous effects, yet the flow is still steady. The diminishing effects of viscosity also result in a stronger vortex. At the highest Reynolds number investigated, the flow is turbulent. Turbulent statistics including tangential and radial velocity fluctuations and Reynolds shear stresses are analyzed for this case in addition to the mean velocity field. The tangential motions of the flow are strongest at Re j = 240. Both the tangential and radial velocity fluctuations increase as the flow spirals toward the center of the reactor. The magnitudes of the tangential and radial velocity fluctuations are similar, suggesting that the turbulence is locally isotropic. (paper)
Vertically grown multiwalled carbon nanotube anode and nickel silicide integrated high performance microsized (1.25 μl) microbial fuel cell

KAUST Repository

Mink, Justine E.

2012-02-08

Microbial fuel cells (MFCs) are an environmentally friendly method for water purification and self-sustained electricity generation using microorganisms. Microsized MFCs can also be a useful power source for lab-on-a-chip and similar integrated devices. We fabricated a 1.25 μL microsized MFC containing an anode of vertically aligned, forest type multiwalled carbon nanotubes (MWCNTs) with a nickel silicide (NiSi) contact area that produced 197 mA/m 2 of current density and 392 mW/m 3 of power density. The MWCNTs increased the anode surface-to-volume ratio, which improved the ability of the microorganisms to couple and transfer electrons to the anode. The use of nickel silicide also helped to boost the output current by providing a low resistance contact area to more efficiently shuttle electrons from the anode out of the device. © 2012 American Chemical Society.
The fabrication of metal silicide nanodot arrays using localized ion implantation

International Nuclear Information System (INIS)

Han, Jin; Kim, Tae-Gon; Min, Byung-Kwon; Lee, Sang Jo

2010-01-01

We propose a process for fabricating nanodot arrays with a pitch size of less than 25 nm. The process consists of localized ion implantation in a metal thin film on a Si wafer using a focused ion beam (FIB), followed by chemical etching. This process utilizes the etching resistivity changes of the ion beam irradiated region that result from metal silicide formation by ion implantation. To control the nanodot diameter, a threshold ion dose model is proposed using the Gaussian distribution of the ion beam intensities. The process is verified by fabricating nanodots with various diameters. The mechanism of etching resistivity is investigated via x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES).
Reclamation and reuse of LEU silicide fuel from manufacturing scrap

International Nuclear Information System (INIS)

Gale, G.R.; Pace, B.W.; Evans, R.S.

2004-01-01

In order to provide an understanding of the organization which is the sole supplier of United States plate type research and test reactor fuel and LEU core conversions, a brief description of the structure and history is presented. Babcock and Wilcox (B and W) is a part of McDermott International, Inc. which is a large diversified corporation employing over 20,000 people primarily in engineering and construction for the off-shore oil and power generation industries throughout the world. B and W provides many energy related products requiring precision machining and high quality systems. This is accomplished by using state-of-the-art equipment, technology and highly skilled people. The RTRFE group within B and W has the ability to produce various complexly shaped fuel elements with a wide variety of fuels and enrichments. B and W RTRFE has fabricated over 200,000 plates since 1981 and gained the diversified experience necessary to satisfy many customer requirements. This accomplishment was possible with the support of McDermott International and all of its resources. B and W has always had a commitment to high quality and integrity. This is apparent by the success and longevity (125 years) of the company. A lower cost to convert cores to LEU provides direct support to RERTR and demonstrates Babcock and Wilcox's commitment to the program. As a supporter of RERTR reactor conversion from HEU to LEU, B and W has contributed a significant amount of R and D money to improve the silicide fuel process which ultimately lowers the LEU core costs. In the most recent R and D project, B and W is constructing a LEU silicide reclamation facility to re-use the unirradiated fuel scrap generated from the production process. Remanufacturing use of this fuel completes the fuel cycle and provides a contribution to LEU cores by reducing scrap inventory and handling costs, lowering initial purchase of fuel due to increasing the process yields, and lowering the replacement costs. This
Status of the atomized uranium silicide fuel development at KAERI

Energy Technology Data Exchange (ETDEWEB)

Kim, C.K.; Kim, K.H.; Park, H.D.; Kuk, I.H. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1997-08-01

While developing KMRR fuel fabrication technology an atomizing technique has been applied in order to eliminate the difficulties relating to the tough property of U{sub 3}Si and to take advantage of the rapid solidification effect of atomization. The comparison between the conventionally comminuted powder dispersion fuel and the atomized powder dispersion fuel has been made. As the result, the processes, uranium silicide powdering and heat treatment for U{sub 3}Si transformation, become simplified. The workability, the thermal conductivity and the thermal compatibility of fuel meat have been investigated and found to be improved due to the spherical shape of atomized powder. In this presentation the overall developments of atomized U{sub 3}Si dispersion fuel and the planned activities for applying the atomizing technique to the real fuel fabrication are described.
Interaction of copper metallization with rare-earth metals and silicides

International Nuclear Information System (INIS)

Molnar, G. L.; Peto, G.; Zsoldos, E.; Horvath, Z. E.

2001-01-01

Solid-phase reactions of copper films with underlying gadolinium, erbium, and erbium - silicide layers on Si(100) substrates were investigated. For the phase analysis, x-ray diffraction and cross-sectional transmission electron microscopy were used. In the case of Cu/Gd/Si(100), an orthorhombic GdSi 2 formed, and, at higher temperatures, copper aggregated into islands. Annealed Cu/Er/Si(100) samples resulted in a hexagonal Er 5 Si 3 phase. In the Cu/ErSi 2-x /Si system, the copper catalyzes the transformation of the highly oriented hexagonal ErSi 2-x phase into hexagonal Er 5 Si 3 . Diverse phase developments of the samples with Gd and Er are based on reactivity differences of the two rare-earth metals. [copyright] 2001 American Institute of Physics
Characterization of uranium silicide powder using XRD

International Nuclear Information System (INIS)

Garcia, Rafael H.L.; Saliba-Silva, Adonis M.; Carvalho, Elita F.U.; Lima, Nelson B.; Ichikawa, Rodrigo U.; Martinez, Luiz G.

2013-01-01

Uranium silicide (U 3 Si 2 ) is an intermetallic used as nuclear fuel in most modern MTR - Materials Test Reactor. Dispersed in aluminum, this fuel allows high uranium densities, up to 4.8 gU/cm 3 . At IPEN, the fabrication of fuel elements based on U 3 Si 2 for the IEA-R1 reactor is carried out in the Nuclear Fuel Center (CCN), by vacuum induction melting of uranium and silicon, followed by grinding. Before employed in a nuclear reactor, U 3 Si 2 must be submitted to a strict quality control, which includes granulometry, density, X-ray radiography for dispersion homogeneity, chemical and crystallographic characterization. Concerning phase composition for a qualified fuel, the fraction of U 3 Si 2 should be higher than 80wt.%. Aiming at the development of a routine methodology for quantification of phases via analysis of XRD data using the Rietved method, six samples from two production baths of CCN were submitted to X-ray diffraction. The data were analyzed using software GSAS and line profile analysis methods. The results suggest that fusion product have preferred orientation and grinding step is important for a better refinement. (author)
Trace metal assay of uranium silicide fuel

International Nuclear Information System (INIS)

Kulkarni, M.J.; Argekar, A.A.; Thulasidas, S.K.; Dhawale, B.A.; Rajeswari, B.; Adya, V.C.; Purohit, P.J.; Neelam, G.; Bangia, T.R.; Page, A.G.; Sastry, M.D.; Iyer, R.H.

1994-01-01

A comprehensive trace metal assay of uranium silicide, a fuel for nuclear research reactors that employs low-enrichment uranium, is carried out by atomic spectrometry. Of the list of specification elements, 21 metallic elements are determined by a direct current (dc) arc carrier distillation technique; the rare earths yttrium and zirconium are chemically separated from the major matrix followed by a dc arc/inductively coupled argon plasma (ICP) excitation technique in atomic emission spectrometry (AES); silver is determined by electrothermal atomization-atomic absorption spectrometry (ETA-AAS) without prior chemical separation of the major matrix. Gamma radioactive tracers are used to check the recovery of rare earths during the chemical separation procedure. The detection limits for trace metallics vary in the 0.1- to 40-ppm range. The precision of the determinations as evaluated from the analysis of the synthetic sample with intermediate range analyte concentration is better than 25% relative standard deviation (RSD) for most of the elements employing dc arc-AES, while that for silver determination by ETS-AAS is 10% RSD. The precision of the determinations for four crucially important rare earths by ICP-AES is better than 3% RSD
Synthesis and properties of a high-capacity iron oxide adsorbent for fluoride removal from drinking water

Science.gov (United States)

Zhang, Chang; Li, Yingzhen; Wang, Ting-Jie; Jiang, Yanping; Fok, Jason

2017-12-01

A novel iron oxide adsorbent with a high fluoride adsorption capacity was prepared by a facile wet-chemical precipitation method and ethanol treatment. The ethanol-treated adsorbent was amorphous and had a high specific surface area. The adsorption capacity of the treated adsorbent was much higher than that of untreated adsorbent. The Langmuir maximum adsorption capacity of the adsorbent prepared at a low final precipitation pH (≤9.0) and treated with ethanol reached 60.8 mg/g. A fast adsorption rate was obtained, and 80% of the adsorption equilibrium capacity was achieved within 2 min. The adsorbent had high fluoride-removal efficiency for water in a wide initial pH range of 3.5-10.3 and had a high affinity for fluoride in the presence of common co-anions. The ethanol treatment resulted in structure transformation of the adsorbent by inhibiting the crystallization of the nano-precipitates. The adsorption was confirmed to be ion exchange between fluoride ions and the hydroxyl groups on the adsorbent surface.
The series production in a standardized fabrication line for silicide fuels and commercial aspects

International Nuclear Information System (INIS)

Wehner, E.L.; Hassel, H.W.

1987-01-01

NUKEM has been responsible for the development and fabrication of LEU fuel elements for MTR reactors under the frame of the German AF program since 1979. The AF program is part of the international RERTR efforts, which were initiated by the INFCE Group in 1978. This paper describes the actual status of development and the transition from the prototype to the series production in a standardized manufacturing line for silicide fuels at NUKEM. Technical provisions and a customer oriented standardized product range aim at an economized manufacturing. (Author)
Behavior of silicon in nitric media. Application to uranium silicides fuels reprocessing; Comportement du silicium en milieu nitrique. Application au retraitement des combustibles siliciures d'uranium

Energy Technology Data Exchange (ETDEWEB)

Cheroux, L

2001-07-01

Uranium silicides are used in some research reactors. Reprocessing them is a solution for their cycle end. A list of reprocessing scenarios has been set the most realistic being a nitric dissolution close to the classic spent fuel reprocessing. This uranium silicide fuel contains a lot of silicon and few things are known about polymerization of silicic acid in concentrated nitric acid. The study of this polymerization allows to point out the main parameters: acidity, temperature, silicon concentration. The presence of aluminum seems to speed up heavily the polymerization. It has been impossible to find an analytical technique smart and fast enough to characterize the first steps of silicic acid polymerization. However the action of silicic species on emulsions stabilization formed by mixing them with an organic phase containing TBP has been studied, Silicon slows down the phase separation by means of oligomeric species forming complex with TBP. The existence of these intermediate species is short and heating can avoid any stabilization. When non irradiated uranium silicide fuel is attacked by a nitric solution, aluminum and uranium are quickly dissolved whereas silicon mainly stands in solid state. That builds a gangue of hydrated silica around the uranium silicide particulates without preventing uranium dissolution. A small part of silicon passes into the solution and polymerize towards the highly poly-condensed forms, just 2% of initial silicon is still in molecular form at the end of the dissolution. A thermal treatment of the fuel element, by forming inter-metallic phases U-Al-Si, allows the whole silicon to pass into the solution and next to precipitate. The behavior of silicon in spent fuels should be between these two situations. (author)
Milling uranium silicide powder for dispersion nuclear fuels

Energy Technology Data Exchange (ETDEWEB)

Vieira, E.; Silva, D.G.; Souza, J.A.B.; Durazzo, M. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Riella, H.G. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

2009-07-01

Full text: Uranium silicide (U3Si2) is presently considered the best fuel qualified so far in terms of uranium loading and performance. Stability of the U3Si2 fuel with uranium density of 4.8 g/cm3 was confirmed by burnup stability tests performed during the Reduced Enrichment for Research and Test Reactors (RERTR) program. This fuel was chosen to compose the first core of the new Brazilian Multipurpose Research Reactor (RMB), planned to be constructed in the next years. This new reactor will consume bigger quantities of U3Si2 powder, when compared with the small consumption of the IEA-R1 research reactor of IPEN-CNEN/SP, the unique MTR type research reactor operating in the country. At the present time, the milling operation of U3Si2 ingots is made manually. In order to increase the powder production capacity, the manual milling must be replaced by an automated procedure. This paper describes a new milling machine and procedure developed to produce U3Si2 powder with higher efficiency. (author)
Simultaneous aluminizing and chromizing of steels to form (Fe,Cr){sub 3}Al coatings and Ge-doped silicide coatings of Cr-Zr base alloys

Energy Technology Data Exchange (ETDEWEB)

Zheng, M.; He, Y.R.; Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

1997-12-01

A halide-activated cementation pack involving elemental Al and Cr powders has been used to achieve surface compositions of approximately Fe{sub 3}Al plus several percent Cr for low alloy steels (T11, T2 and T22) and medium carbon steel (1045 steel). A two-step treatment at 925 C and 1150 C yields the codeposition and diffusion of aluminum and chromium to form dense and uniform ferrite coatings of about 400 {micro}m thickness, while preventing the formation of a blocking chromium carbide at the substrate surfaces. Upon cyclic oxidation in air at 700 C, the coated steel exhibits a negligible 0.085 mg/cm{sup 2} weight gain for 1900 one-hour cycles. Virtually no attack was observed on coated steels tested at ABB in simulated boiler atmospheres at 500 C for 500 hours. But coatings with a surface composition of only 8 wt% Al and 6 wt% Cr suffered some sulfidation attack in simulated boiler atmospheres at temperatures higher than 500 C for 1000 hours. Two developmental Cr-Zr based Laves phase alloys (CN129-2 and CN117(Z)) were silicide/germanide coated. The cross-sections of the Ge-doped silicide coatings closely mimicked the microstructure of the substrate alloys. Cyclic oxidation in air at 1100 C showed that the Ge-doped silicide coating greatly improved the oxidation resistance of the Cr-Zr based alloys.
Ytterbium silicide (YbSi{sub 2}). A promising thermoelectric material with a high power factor at room temperature

Energy Technology Data Exchange (ETDEWEB)

Tanusilp, Sora-at; Ohishi, Yuji; Muta, Hiroaki [Graduate School of Engineering, Osaka University, Suita, Osaka (Japan); Yamanaka, Shinsuke [Graduate School of Engineering, Osaka University, Suita, Osaka (Japan); Research Institute of Nuclear Engineering, University of Fukui, Tsuruga (Japan); Nishide, Akinori [Graduate School of Engineering, Osaka University, Suita, Osaka (Japan); Center for Exploratory Research, Research and Development Group, Hitachi, Ltd., Kokubunji, Tokyo (Japan); Hayakawa, Jun [Center for Exploratory Research, Research and Development Group, Hitachi, Ltd., Kokubunji, Tokyo (Japan); Kurosaki, Ken [Graduate School of Engineering, Osaka University, Suita, Osaka (Japan); Research Institute of Nuclear Engineering, University of Fukui, Tsuruga (Japan); JST, PRESTO, Kawaguchi, Saitama (Japan)

2018-02-15

Metal silicide-based thermoelectric (TE) materials have attracted attention in the past two decades, because they are less toxic, with low production cost and high chemical stability. Here, we study the TE properties of ytterbium silicide YbSi{sub 2} with a specific layered structure and the mixed valence state of Yb{sup 2+} and Yb{sup 3+}. YbSi{sub 2} exhibits large Seebeck coefficient, S, accompanied by high electrical conductivity, σ, leading to high power factor, S{sup 2}σ, of 2.2 mW m{sup -1} K{sup -2} at room temperature, which is comparable to those of state-of-the-art TE materials such as Bi{sub 2}Te{sub 3} and PbTe. Moreover, YbSi{sub 2} exhibits high Grueneisen parameter of 1.57, which leads to relatively low lattice thermal conductivity, κ{sub lat}, of 3.0 W m{sup -1} K{sup -1} at room temperature. The present study reveals that YbSi{sub 2} can be a good candidate of TE materials working near room temperature. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Rate Theory Modeling and Simulations of Silicide Fuel at LWR Conditions

Energy Technology Data Exchange (ETDEWEB)

Miao, Yinbin [Argonne National Lab. (ANL), Argonne, IL (United States); Ye, Bei [Argonne National Lab. (ANL), Argonne, IL (United States); Mei, Zhigang [Argonne National Lab. (ANL), Argonne, IL (United States); Hofman, Gerard [Argonne National Lab. (ANL), Argonne, IL (United States); Yacout, Abdellatif [Argonne National Lab. (ANL), Argonne, IL (United States)

2015-12-10

Uranium silicide (U₃Si₂) fuel has higher thermal conductivity and higher uranium density, making it a promising candidate for the accident-tolerant fuel (ATF) used in light water reactors (LWRs). However, previous studies on the fuel performance of U₃Si₂, including both experimental and computational approaches, have been focusing on the irradiation conditions in research reactors, which usually involve low operation temperatures and high fuel burnups. Thus, it is important to examine the fuel performance of U₃Si₂ at typical LWR conditions so as to evaluate the feasibility of replacing conventional uranium dioxide fuel with this silicide fuel material. As in-reactor irradiation experiments involve significant time and financial cost, it is appropriate to utilize modeling tools to estimate the behavior of U₃Si₂ in LWRs based on all those available research reactor experimental references and state-of-the-art density functional theory (DFT) calculation capabilities at the early development stage. Hence, in this report, a comprehensive investigation of the fission gas swelling behavior of U₃Si₂ at LWR conditions is introduced. The modeling efforts mentioned in this report was based on the rate theory (RT) model of fission gas bubble evolution that has been successfully applied for a variety of fuel materials at devious reactor conditions. Both existing experimental data and DFT-calculated results were used for the optimization of the parameters adopted by the RT model. Meanwhile, the fuel-cladding interaction was captured by the coupling of the RT model with simplified mechanical correlations. Therefore, the swelling behavior of U₃Si₂ fuel and its consequent interaction with cladding in LWRs was predicted by the rate theory modeling, providing valuable information for the development of U₃Si₂ fuel as an accident
CEMS Investigations of Fe-Silicide Phases Formed by the Method of Concentration Controlled Phase Selection

Energy Technology Data Exchange (ETDEWEB)

Moodley, M. K.; Bharuth-Ram, K. [University of Durban-Westville, Physics Department (South Africa); Waal, H. de; Pretorius, R. [University of Stellenbosch, Physics Department (South Africa)

2002-03-15

Conversion electron Moessbauer spectroscopy (CEMS) measurements have been made on Fe-silicide samples formed using the method of concentration controlled phase selection. To prepare the samples a 10 nm layer of Fe{sub 30}M{sub 70} (M=Cr, Ni) was evaporated onto Si(100) surfaces, followed by evaporation of a 60 nm Fe layer. Diffusion of the Fe into the Si substrate and the formation of different Fe-Si phases was achieved by subjecting the evaporated samples to a series of heating stages, which consisted of (a) a 10 min anneal at 800 deg. C plus etch of the residual surface layer, (b) a further 3 hr anneal at 800 deg. C, (c) a 60 mJ excimer laser anneal to an energy density of 0.8 J/cm{sup 2}, and (d) a final 3 hr anneal at 800 deg. C. CEMS measurements were used to track the Fe-silicide phases formed. The CEMS spectra consisted of doublets which, based on established hyperfine parameters, could be assigned to {alpha}- or {beta}-FeSi{sub 2} or cubic FeSi. The spectra showed that {beta}-FeSi{sub 2} had formed already at the first annealing stage. Excimer laser annealing resulted in the formation of a phase with hyperfine parameters consistent with those of {alpha}-FeSi{sub 2}. A further 3 hr anneal at 800 deg. C resulted in complete reversal to the semiconducting {beta}-FeSi{sub 2} phase.
Spent fuel from nuclear research reactors immobilized in sintered glass

International Nuclear Information System (INIS)

Mateos, P.; Russo, D.O.; Rodriguez, D.; Heredia, A.; Sanfilippo, M.; Sterba, M.

2002-01-01

Different kinds of glasses, borosilicates, Iron borosilicates and Iron phosphates, were tested in order to determine its capability to immobilize calcined uranium silicide in a sintering process. Iron phosphate glass developed in our laboratory showed the best results in SEM analysis. Also its gravimetric leaching rate is less than 0.45 g.m -2 .day -1 for 7 and 10% loading which is lower than any previously studied for us. (author)
Impurity Precipitation, Dissolution, Gettering and Passivation in PV Silicon: Final Technical Report, 30 January 1998--29 August 2001

Energy Technology Data Exchange (ETDEWEB)

Weber, E. R.

2002-02-01

This report describes the major progress in understanding the physics of transition metals in silicon and their possible impact on the efficiency of solar cells that was achieved during the three-year span of this subcontract. We found that metal-silicide precipitates and dissolved 3d transition metals can be relatively easily gettered. Gettering and passivating treatments must take into account the individuality of each transition metal. Our studies demonstrated how significant is the difference between defect reactions of copper and iron. Copper does not significantly affect the minority-carrier diffusion length in p-type silicon, at least as long as its concentration is low, but readily precipitates in n-type silicon. Therefore, copper precipitates may form in the area of p-n junctions and cause shunts in solar cells. Fortunately, copper precipitates are present mostly in the chemical state of copper-silicide and can relatively easily be dissolved. In contrast, iron was found to form clusters of iron-oxides and iron-silicates in the wafers. These clusters are thermodynamically stable even in high temperatures and are extremely difficult to remove. The formation of iron-silicates was observed at temperatures over 900C.
Submicron Features in Higher Manganese Silicide

Directory of Open Access Journals (Sweden)

Yatir Sadia

2013-01-01

Full Text Available The world energy crisis had increased the demand for alternative energy sources and as such is one of the topics at the forefront of research. One way for reducing energy consumption is by thermoelectricity. Thermoelectric effects enable direct conversion of thermal into electrical energy. Higher manganese silicide (HMS, MnSi1.75 is one of the promising materials for applications in the field of thermoelectricity. The abundance and low cost of the elements, combined with good thermoelectric properties and high mechanical and chemical stability at high temperatures, make it very attractive for thermoelectric applications. Recent studies have shown that Si-rich HMS has improved thermoelectric properties. The most interesting of which is the unusual reduction in thermal conductivity. In the current research, transmission (TEM and scanning (SEM electron microscopy as well as X-ray diffraction methods were applied for investigation of the govern mechanisms resulting in very low thermal conductivity values of an Si-rich HMS composition, following arc melting and hot-pressing procedures. In this paper, it is shown that there is a presence of sub-micron dislocations walls, stacking faults, and silicon and HMS precipitates inside each other apparent in the matrix, following a high temperature (0.9 Tm hot pressing for an hour. These are not just responsible for the low thermal conductivity values observed but also indicate the ability to create complicate nano-structures that will last during the production process and possibly during the application.
Development of Self-Healing Zirconium-Silicide Coatings for Improved Performance Zirconium-Alloy Fuel Cladding

Energy Technology Data Exchange (ETDEWEB)

Sridharan, Kumar [University of Wisconsin-Madison; Mariani, Robert [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bai, Xianming [Idaho National Lab. (INL), Idaho Falls, ID (United States); Xu, Peng [Westinghouse Electric Company; Lahoda, Ed [Westinghouse Electric Company

2018-03-31

Given the long-term goal of developing such coatings for use with nuclear reactor fuel cladding, this work describes results of oxidation and corrosion behavior of bulk zirconium-silicide and fabrication of zirconium-silicide coatings on zirconium-alloy test flats, tube configurations, and SiC test flats. In addition, boiling heat transfer of these modified surfaces (including ZrSi2 coating) during clad quenching experiments is discussed in detail. Oxidation of bulk ZrSi2 was found to be negligible compared to Zircaloy-4 (a common Zr-alloy cladding material) and mechanical integrity of ZrSi2 was superior to that of bulk Zr2Si at high temperatures in ambient air. Very interesting and unique multi-nanolayered composite of ZrO2 and SiO2 were observed. Physical model for the oxidation has been proposed wherein Zr–Si–O mixture undergoes a spinodal phase decomposition into ZrO2 and SiO2, which is manifested as a nanoscale assembly of alternating layer of the two oxides. Steam corrosion at high pressure (10.3 MPa) led to weight loss of ZrSi2 and produced oxide scale with depletion of silicon, possibly attributed to volatile silicon hydroxide, gaseous silicon monoxide, and a solubility of silicon dioxide in water. Only Zircon phase (ZrSiO4) formed during oxidation of ZrSi2 at 1400°C in air, and allowed for immobilization silicon species in oxide scale in the aqueous environments. Zirconium-silicide coatings (on zirconium-alloy substrates) investigated in this study were deposited primarily using magnetron sputter deposition method and slurry method, although powder spray deposition processes cold spray and thermal spray methods were also investigated. The optimized ZrSi2 sputtered coating exhibited a highly protective nature at elevated temperatures in ambient air by mitigating oxygen permeation to the underlying zirconium alloy substrate. The high oxidation resistance of the coating has been shown to be due to nanocrystalline SiO2 and ZrSiO4 phases in the amorphous

Safety analysis of RSG-GAS Silicide core using one line cooling system

International Nuclear Information System (INIS)

Endiah-Puji-Hastuti

2003-01-01

In the frame of minimizing the operation-cost, operation mode using one line cooling system is being evaluated. Maximum reactor has been determined and to continuing this program, steady state and transient analysis were done. The analysis was done by means of a core thermal hydraulic code, COOLOD-N, and PARET. The codes solves core thermal hydraulic equation at steady state conditions and transient, respectively. By using silicide core data and coast down flow rate as the input, thermal hydraulics parameters such as fuel cladding and fuel meat temperatures as well as safety margin against flow instability were calculated. Imposing the safety criteria to the results of steady state and transient analysis, maximum permissible power for this operation was obtained as much as 17.1 MW
X-ray absorption fine structure (XAFS) studies of cobalt silicide thin films

International Nuclear Information System (INIS)

Naftel, S.J.; Coulthard, I.; Hu, Y.; Sham, T.K.; Zinke-Allmang, M.

1998-01-01

Cobalt silicide thin films, prepared on Si(100) wafers, have been studied by X-ray absorption near edge structures (XANES) at the Si K-, L 2,3 - and Co K-edges utilizing both total electron (TEY) and fluorescence yield (FLY) detection as well as extended X-ray absorption fine structure (EXAFS) at the Co K-edge. Samples made using DC sputter deposition on clean Si surfaces and MBE were studied along with a bulk CoSi 2 sample. XANES and EXAFS provide information about the electronic structure and morphology of the films. It was found that the films studied have essentially the same structure as bulk CoSi 2 . Both the spectroscopy and materials characterization aspects of XAFS (X-ray absorption fine structures) are discussed
Study of surface segregation of Si on palladium silicide using Auger electron spectroscopy

International Nuclear Information System (INIS)

Abhaya, S; Amarendra, G; Gopalan, Padma; Reddy, G L N; Saroja, S

2004-01-01

The transformation of Pd/Si to Pd 2 Si/Si is studied using Auger electron spectroscopy over a wide temperature range of 370-1020 K. The Pd film gets totally converted to Pd 2 Si upon annealing at 520 K, and beyond 570 K, Si starts segregating on the surface of silicide. It is found that the presence of surface oxygen influences the segregation of Si. The time evolution study of Si segregation reveals that segregation kinetics is very fast and the segregated Si concentration increases as the temperature is increased. Scanning electron microscopy measurements show that Pd 2 Si is formed in the form of islands, which grow as the annealing temperature is increased
Program description for the qualification of CNEA - Argentina as a supplier of LEU silicide fuel and post-irradiation examinations plan for the first prototype irradiated in Argentina

International Nuclear Information System (INIS)

Rugirello, Gabriel; Adelfang, Pablo; Denis, Alicia; Zawerucha, Andres; Marco, Agustin di; Guillaume, Eduardo; Sbaffoni, Monica; Lacoste, Pablo

1998-01-01

In this report we present a description of the ongoing and future stages of the program for the qualification of CNEA, Argentina, as a supplier of low enriched uranium silicide fuel elements for research reactor. Particularly we will focus on the characteristics of the future irradiation experiment on a new detachable prototype, the post-irradiation examinations (PIE) plan for the already irradiated prototype PO4 and an overview of the recently implemented PIE facilities and equipment. The program is divided in several steps, some of which have been already completed. It concludes: development of the uranium silicide fissile material, irradiation and PIE of several full-scale prototypes. Important investments have been already carried out in the facilities for the FE production and PIE. (author)
Silicide formation by Ar/sup +/ ion bombardment of Pd/Si

Energy Technology Data Exchange (ETDEWEB)

Lee, R Y; Whang, C N; Kim, H K; Smith, R J

1988-08-01

Palladium films, 45 nm thick, evaporated on to Si(111) were irradiated to various doses with 78 keV Ar/sup +/ ions to promote silicide formation. Rutherford backscattering spectroscopy (RBS) shows that intermixing has occurred across the Pd/Si interface at room temperature. The mixing behaviour is increased with dose which coincides well with the theoretical model of cascade mixing. The absence of deep RBS tails for palladium and the small area of this for silicon spectra indicate that short-range mixing occurs. From the calculated damage profiles computed with TRIM code, the dominant diffusion species is found to be silicon atoms in the Pd/Si system. It is also found that the initial compound formed by Ar/sup +/ irradiation is Pd/sub 2/Si which increases with dose. At a dose of 1 x 10/sup 16/ Ar/sup +/ cm/sup -2/, a 48 nm thickness of Pd/sub 2/Si was formed by ion-beam mixing at room temperature.
Preparation and Optimization of Amorphous Ursodeoxycholic Acid Nano-suspensions by Nanoprecipitation based on Acid-base Neutralization for Enhanced Dissolution.

Science.gov (United States)

Xie, Yike; Chen, Zhongjian; Su, Rui; Li, Ye; Qi, Jianping; Wu, Wei; Lu, Yi

2017-01-01

Ursodeoxycholic acid, usually used to dissolve cholesterol gallstones in clinic, is a typical hydrophobic drug with poor oral bioavailability due to dissolution rate-limited performance. The objective of this study was to increase the dissolution of ursodeoxycholic acid by amorphous nanosuspensions. Nanoprecipitation based on acid-base neutralization was used to prepare the nanosuspensions with central composite design to optimize the formula. The nanosuspensions were characterized by particle size, morphology, crystallology and dissolution. The ursodeoxycholic acid nanosuspensions showed mean particle size around 380 nm with polydispersion index value about 0.25. Scanning electron microscope observed high coverage of HPMC-E50 onto the surface of the nanosuspensions. Differential scanning calorimetry and powder X-ray diffractometry revealed amorphous structure of the ursodeoxycholic acid nanosuspensions. A significant increase of dissolution in acidic media was achieved by the amorphous nanosuspensions compared with the physical mixture. It can be predicted that the amorphous nanosuspensions show great potential in improving the oral bioavailability of ursodeoxycholic acid. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.
The ability of silicide coating to delay the catastrophic oxidation of vanadium under severe conditions

Energy Technology Data Exchange (ETDEWEB)

Chaia, N., E-mail: nabil.chaia@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour – UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy Cedex (France); Mathieu, S., E-mail: stephane.mathieu@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour – UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy Cedex (France); Rouillard, F., E-mail: fabien.rouillard@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, F-91191 Gif-sur-Yvette (France); Vilasi, M., E-mail: michel.vilasi@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour – UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy Cedex (France)

2015-02-15

Highlights: • Oxidation protection is due to the formation of a pure silica layer. • V–4Cr–4Ti with V{sub x}Si{sub y} silicide coating withstands 400 1-h cycles (1100 °C-T{sub amb}) in air. • Three-point flexure testing at 950 °C and 75 MPa does not induce coating breakdown. • No delamination between coating and substrate is observed in any test. - Abstract: V–4Cr–4Ti vanadium alloy is a potential cladding material for sodium-cooled fast-neutron reactors (SFRs). However, its affinity for oxygen and the subsequent embrittlement that oxygen induces causes a need for an oxygen diffusion barrier, which can be obtained by manufacturing a multi-layered silicide coating. The present work aims to evaluate the effects of thermal cycling (using a cyclic oxidation device) and tensile and compressive stresses (using the three-point flexure test) on the coated alloy system. Tests were performed in air up to 1100 °C, which is 200 °C higher than the accidental temperature for SFR applications. The results showed that the VSi{sub 2} coating was able to protect the vanadium substrate from oxidation for more than 400 1-h cycles between 1100 °C and room temperature. The severe bending applied to the coated alloy at 950 °C using a load of 75 MPa did not lead to specimen breakage. It can be suggested that the VSi{sub 2} coating has mechanical properties compatible with the V–4Cr–4Ti alloy for SFR applications.
Technical report: technical development on the silicide plate-type fuel experiment at nuclear safety research reactor

International Nuclear Information System (INIS)

Yanagisawa, Kazuaki; Soyama, Kazuhiko; Ichikawa, Hiroki

1991-08-01

According to a reduction of fuel enrichment from 45 w/o 235 U to 20 w/o, an aluminide plate-type fuel used currently in the domestic research and material testing reactors will be replaced by a silicide plate-type one. One of the major concern arisen from this alternation is to understand the fuel behavior under simulated reactivity initiated accident (RIA) conditions, this is strongly necessary from the safety and licensing point of view. The in-core RIA experiments are, therefore, carried out at Nuclear Safety Research Reactor (NSRR) in Japan Atomic Energy Research Institute (JAERI). The silicide plate-type fuel consisted of the ternary alloy of U-Al-Si as a meat with uranium density up to 4.8 g/cm 3 having thickness by 0.51 mm and the binary alloy of Al-3%Mg as a cladding by thickness of 0.38 mm. Comparison of the physical properties of this metallic plate fuel with the UO 2 -zircaloy fuel rod used conventionally in commercial light water reactors shows that the heat conductivity of the former is of the order of about 13 times greater than the latter, however the melting temperature is only one-half (1570degC). Prior to in-core RIA experiments, there were some difficulties lay in our technical path. This report summarized the technical achievements obtained through our four years work. (J.P.N.)
First-principles investigations of the physical properties of binary uranium silicide alloys

International Nuclear Information System (INIS)

Yang, Jin; Long, Jianping; Yang, Lijun; Li, Dongmei

2013-01-01

Graphical abstract: Total density of states for USi 2 . Display Omitted -- Abstract: The structural, elastic properties and the Debye temperature of binary Uranium Silicide (U-Si) alloys are investigated by using the first-principles plane-wave pseudopotential density function theory within the generalized gradient approximation (GGA). The ground states properties are found to agree with the available experimental data. The mechanical properties like shear modulus, Young’s modulus, Poisson’s ratio σ and ratio B/G are also calculated. Finally, The averaged sound velocity (v m ), the longitudinal sound velocity (v l ), transverse sound velocity (v t ) and the Debye temperature (θ D ) are obtained. However, the theoretical values are slightly different from few existed experiment data because the latter was obtained at room temperature while the former one at 0 K
Creation of Y{sub 2}Ti{sub 2}O{sub 7} nanoprecipitates to strengthen the Fe-14Cr-3Al-2W steels by adding Ti hydride and Y{sub 2}O{sub 3} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wang, Linbo; Bai, Zhonglian; Shen, Hailong; Wang, Chenxi; Liu, Tong, E-mail: tongliu@buaa.edu.cn

2017-05-15

In order to prohibit the formation of large Y-Al-O precipitates, Ti hydride nanoparticles (NPs) were prepared and used to replace Ti as raw particles to fabricate the oxide dispersion strengthened (ODS) Fe-14Cr-3Al-2W-0.35Y{sub 2}O{sub 3} steels by mechanical alloying (MA) and hot isostatic pressing (HIP). As the content of Ti hydride increases from 0.1 to 0.5 and 1.0 wt%, the oxide nanoprecipitates in the ODS steels changes from Y{sub 3}Al{sub 5}O{sub 12} phase to Y{sub 2}Ti{sub 2}O{sub 7} phase (semicoherent with the matrix), and the particle size is successfully reduced. The tensile strength of the ODS steel increases remarkably with increasing Ti hydride content. The sample with 1.0 wt% Ti hydride exhibits a high strength of 1049 MPa at 25 °C and 278 MPa at 700 °C. The creation of Y{sub 2}Ti{sub 2}O{sub 7} nanoprecipitates by adding Ti hydride NPs opens a new way to control the structure and size of the oxide precipitates in the ODS steels. - Graphical abstract: The creation of Y{sub 2}Ti{sub 2}O{sub 7} nanoprecipitates by adding Ti hydride nanoparticles remarkably increases the mechanical properties of the Al-containing ODS steels. - Highlights: •TiH{sub 1.971} reacts with Y{sub 2}O{sub 3} to form Y{sub 2}Ti{sub 2}O{sub 7} in the Al-containing ODS steel. •Addition of TiH{sub 1.971} nanoparticles can prevent the formation of Y-Al-O phases. •Y{sub 2}Ti{sub 2}O{sub 7} nanoparticles share semicoherent interface with the ferrite matrix. •The mean size of oxide dispersion is reduced to 11.2 ± 7.1 nm with 1.0 wt% TiH{sub 1.971}. •The tensile strength of the ODS steel enlarges with increasing TiH{sub 1.971} content.
Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

Science.gov (United States)

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

2015-07-14

Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One system operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.
Bimetallic low thermal-expansion panels of Co-base and silicide-coated Nb-base alloys for high-temperature structural applications

International Nuclear Information System (INIS)

Rhein, R.K.; Novak, M.D.; Levi, C.G.; Pollock, T.M.

2011-01-01

Research highlights: → Low net thermal expansion bimetallic structural lattice constructed. → Temperatures on the order of 1000 deg. C reached. → Improved silicide coating for niobium alloy developed. - Abstract: The fabrication and high temperature performance of low thermal expansion bimetallic lattices composed of Co-base and Nb-base alloys have been investigated. A 2D sheet lattice with a coefficient of thermal expansion (CTE) lower than the constituent materials of construction was designed for thermal cycling to 1000 deg. C with the use of elastic-plastic finite element analyses. The low CTE lattice consisted of a continuous network of the Nb-base alloy C-103 with inserts of high CTE Co-base alloy Haynes 188. A new coating approach wherein submicron alumina particles were incorporated into (Nb, Cr, Fe) silicide coatings was employed for oxidation protection of the Nb-base alloy. Thermal gravimetric analysis results indicate that the addition of submicron alumina particles reduced the oxidative mass gain by a factor of four during thermal cycling, increasing lifetime. Bimetallic cells with net expansion of 6 x 10 -6 /deg. C and 1 x 10 -6 /deg. C at 1000 deg. C were demonstrated and their measured thermal expansion characteristics were consistent with analytical models and finite element analysis predictions.
Mixing of Al into uranium silicides reactor fuels

International Nuclear Information System (INIS)

Ding, F.R.; Birtcher, R.C.; Kestel, B.J.; Baldo, P.M.

1996-11-01

SEM observations have shown that irradiation induced interaction of the aluminum cladding with uranium silicide reactor fuels strongly affects both fission gas and fuel swelling behaviors during fuel burn-up. The authors have used ion beam mixing, by 1.5 MeV Kr, to study this phenomena. RBS and the 27 Al(p, γ) 28 Si resonance nuclear reaction were used to measure radiation induced mixing of Al into U 3 Si and U 3 Si 2 after irradiation at 300 C. Initially U mixes into the Al layer and Al mixes into the U 3 Si. At a low dose, the Al layer is converted into UAl 4 type compound while near the interface the phase U(Al .93 Si .07 ) 3 grows. Under irradiation, Al diffuses out of the UAl 4 surface layer, and the lower density ternary, which is stable under irradiation, is the final product. Al mixing into U 3 Si 2 is slower than in U 3 Si, but after high dose irradiation the Al concentration extends much farther into the bulk. In both systems Al mixing and diffusion is controlled by phase formation and growth. The Al mixing rates into the two alloys are similar to that of Al into pure uranium where similar aluminide phases are formed
Formation of ferromagnetic interface between β-FeSi2 and Si(111) substrate

International Nuclear Information System (INIS)

Hattori, Azusa N.; Hattori, Ken; Kodama, Kenji; Hosoito, Nobuyoshi; Daimon, Hiroshi

2007-01-01

Epitaxial β-FeSi 2 thin films were grown on Si(111)7x7 clean surfaces by solid phase epitaxy in ultrahigh vacuum: iron deposition at low temperature and subsequent annealing. We found that a ferromagnetic interface layer of iron-rich silicides forms between a β-FeSi 2 surface layer and a Si(111) substrate spontaneously from transmission electron microscopy observations and magnetization measurements
Shock Melting of Iron Silicide as Determined by In Situ X-ray Diffraction.

Science.gov (United States)

Newman, M.; Kraus, R. G.; Wicks, J. K.; Smith, R.; Duffy, T. S.

2016-12-01

The equation of state of core alloys at pressures and temperatures near the solid-liquid coexistence curve is important for understanding the dynamics at the inner core boundary of the Earth and super-Earths. Here, we present a series of laser driven shock experiments on textured polycrystalline Fe-15Si. These experiments were conducted at the Omega and Omega EP laser facilities. Particle velocities in the Fe-15Si samples were measured using a line VISAR and were used to infer the thermodynamic state of the shocked samples. In situ x-ray diffraction measurements were used to probe the melting transition and investigate the potential decomposition of Fe-15Si in to hcp and B2 structures. This work examines the kinetic effects of decomposition due to the short time scale of dynamic compression experiments. In addition, the thermodynamic data collected in these experiments adds to a limited body of information regarding the equation of state of Fe-15Si, which is a candidate for the composition in Earth's outer core. Our experimental results show a highly textured solid phase upon shock compression to pressures ranging from 170 to 300 GPa. Below 320 GPa, we observe diffraction peaks consistent with decomposition of the D03 starting material in to an hcp and a cubic (potentially B2) structure. Upon shock compression above 320 GPa, the intense and textured solid diffraction peaks give way to diffuse scattering and loss of texture, consistent with melting along the Hugoniot. When comparing these results to that of pure iron, we can ascertain that addition of 15 wt% silicon increases the equilibrium melting temperature significantly, or that the addition of silicon significantly increases the metastability of the solid phase, relative to the liquid. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Nickel silicide formation in silicon implanted nickel

Science.gov (United States)

Rao, Z.; Williams, J. S.; Pogany, A. P.; Sood, D. K.; Collins, G. A.

1995-04-01

Nickel silicide formation during the annealing of very high dose (≥4.5×1017 ions/cm2) Si implanted Ni has been investigated, using ion beam analytical techniques, electron microscopy, and x-ray diffraction analysis. An initial amorphous Si-Ni alloy, formed as a result of high dose ion implantation, first crystallized to Ni2Si upon annealing in the temperature region of 200-300 °C. This was followed by the formation of Ni5Si2 in the temperature region of 300-400 °C and then by Ni3Si at 400-600 °C. The Ni3Si layer was found to have an epitaxial relationship with the substrate Ni, which was determined as Ni3Si∥Ni and Ni3Si∥Ni for Ni(100) samples. The minimum channeling yield in the 2 MeV He Rutherford backscattering and channeling spectra of this epitaxial layer improved with higher annealing temperatures up to 600 °C, and reached a best value measured at about 8%. However, the epitaxial Ni3Si dissolved after long time annealing at 600 °C or annealing at higher temperatures to liberate soluble Si into the Ni substrate. The epitaxy is attributed to the excellent lattice match between the Ni3Si and the Ni. The annealing behavior follows the predictions of the Ni-Si phase diagram for this nickel-rich binary system.
Irradiation of an uranium silicide prototype in RA-3 reactor

International Nuclear Information System (INIS)

Calabrese, R.; Estrik, G.; Notari, C.

1996-01-01

The factibility of irradiation of an uranium silicide (U 3 Si 2 ) prototype in the RA-3 reactor was studied. The standard RA-3 fuel element uses U 3 O 8 as fissible material. The enrichment of both standard and prototype is the same: 20% U 235 and also the frame geometry and number of plates is identical. The differences are in the plate dimensions and the fissile content which is higher in the prototype. The cooling conditions of the core allow the insertion of the prototype in any core position, even near the water trap, if the overall power is kept below 5Mw. Nevertheless, the recommendation was to begin irradiation near the periphery and later on move the prototype towards more central positions in order to increase the burnup rate. The prototype was effectively introduced in a peripheral position and the thermal fluxes were measured between plates with the foil activation technique. These were also evaluated with the fuel management codes and a reasonable agreement was found. (author). 5 refs., 3 figs., 3 tabs
Iron and stony-iron meteorites

DEFF Research Database (Denmark)

Ruzicka, Alex M.; Haack, Henning; Chabot, Nancy L.

2017-01-01

By far most of the melted and differentiated planetesimals that have been sampled as meteorites are metal-rich iron meteorites or stony iron meteorites. The parent asteroids of these meteorites accreted early and differentiated shortly after the solar system formed, producing some of the oldest...... and interpretations for iron and stony iron meteorites (Plate 13.1). Such meteorites provide important constraints on the nature of metal-silicate separation and mixing in planetesimals undergoing partial to complete differentiation. They include iron meteorites that formed by the solidification of cores...... (fractionally crystallized irons), irons in which partly molten metal and silicates of diverse types were mixed together (silicate-bearing irons), stony irons in which partly molten metal and olivine from cores and mantles were mixed together (pallasites), and stony irons in which partly molten metal...
Evaluation Of Radioactivity Concentration In The Primary Cooling Water System Of The RSG-GAS During Operation With 30% Silicide Fuels

International Nuclear Information System (INIS)

Hartoyo, Unggul; Udiyani, P.M.; Setiawanto, Anto

2001-01-01

The evaluating radioactivity concentration in the primary cooling water of the RSG-GAS during operation with 30% silicide fuels has been performed. The method of the research is sampling of primary cooling water during operation of the reactor and calculation of its radioactivity concentration. Based on the data obtained from calculation, the identified nuclides in the water are, Mn-56, Sb-124, Sb-122 and Na-24, under the limit of safety value
A study of strain in thin epitaxial films of yttrium silicide on Si(111)

Science.gov (United States)

Siegal, Michelle F.; Martínez-Miranda, L. J.; Santiago-Avilés, J. J.; Graham, W. R.; Siegal, M. P.

1994-02-01

We present the results of an x-ray diffraction analysis of epitaxial yttrium silicide films grown on Si(111), with thicknesses ranging from 14 to 100 Å. The macroscopic strain along the out-of-plane direction for films containing pits or pinholes follows the trend observed previously in films of thicknesses up to 510 Å. The out-of-plane lattice parameter decreases linearly with film thickness. We show preliminary evidence that pinhole-free films do not follow the above trend, and that strain in these films has the opposite sign than in films with pinholes. Finally, our results also indicate that the mode of growth, coupled to the interfacial thermal properties of the films, affects the observed value for the strain in the films.

A study of strain in thin epitaxial films of yttrium silicide on Si(111)

International Nuclear Information System (INIS)

Siegal, M.F.; Martinez-Miranda, L.J.; Santiago-Aviles, J.J.; Graham, W.R.; Siegal, M.P.

1994-01-01

We present the results of an x-ray diffraction analysis of epitaxial yttrium silicide films grown on Si(111), with thicknesses ranging from 14 to 100 A. The macroscopic strain along the out-of-plane direction for films containing pits or pinholes follows the trend observed previously in films of thicknesses up to 510 A. The out-of-plane lattice parameter decreases linearly with film thickness. We show preliminary evidence that pinhole-free films do not follow the above trend, and that strain in these films has the opposite sign than in films with pinholes. Finally, our results also indicate that the mode of growth, coupled to the interfacial thermal properties of the films, affects the observed value for the strain in the films
Construction of a four tip scanning tunneling microscope/scanning electron microscope combination and conductivity measurements of silicide nanowires

International Nuclear Information System (INIS)

Zubkov, Evgeniy

2013-01-01

In this work the combination of a four-tip scanning tunneling microscope with a scanning electron microscope is presented. By means of this apparatus it is possible to perform the conductivity measurements on the in-situ prepared nanostructures in ultra-high vacuum. With the aid of a scanning electron microscope (SEM), it becomes possible to position the tunneling tips of the four-tip scanning tunneling microscope (STM), so that an arrangement for a four-point probe measurement on nanostructures can be obtained. The STM head was built according to the novel coaxial Beetle concept. This concept allows on the one hand, a very compact arrangement of the components of the STM and on the other hand, the new-built STM head has a good mechanical stability, in order to achieve atomic resolution with all four STM units. The atomic resolution of the STM units was confirmed by scanning a Si(111)-7 x 7 surface. The thermal drift during the STM operation, as well as the resonant frequencies of the mechanical structure of the STM head, were determined. The scanning electron microscope allows the precise and safe navigation of the tunneling tips on the sample surface. Multi tip spectroscopy with up to four STM units can be performed synchronously. To demonstrate the capabilities of the new-built apparatus the conductivity measurements were carried out on metallic yttrium silicide nanowires. The nanowires were prepared by the in-situ deposition of yttrium on a heated Si(110) sample surface. Current-voltage curves were recorded on the nanowires and on the wetting layer in-between. The curves indicate an existence of the Schottky barrier between the yttrium silicide nanowires and the silicon bulk. By means of the two-tip measurements with a gate, the insulating property of the Schottky barrier has been confirmed. Using this Schottky barrier, it is possible to limit the current to the nanowire and to prevent it from flowing through the silicon bulk. A four-tip resistance measurement
Iron and stony-iron meteorites

DEFF Research Database (Denmark)

Benedix, Gretchen K.; Haack, Henning; McCoy, T. J.

2014-01-01

Without iron and stony-iron meteorites, our chances of ever sampling the deep interior of a differentiated planetary object would be next to nil. Although we live on a planet with a very substantial core, we will never be able to sample it. Fortunately, asteroid collisions provide us with a rich...... sampling of the deep interiors of differentiated asteroids. Iron and stony-iron meteorites are fragments of a large number of asteroids that underwent significant geological processing in the early solar system. Parent bodies of iron and some stony-iron meteorites completed a geological evolution similar...... to that continuing on Earth – although on much smaller length- and timescales – with melting of the metal and silicates; differentiation into core, mantle, and crust; and probably extensive volcanism. Iron and stony-iron meteorites are our only available analogues to materials found in the deep interiors of Earth...
Contributions to the preparation of 241americium metal and a few 241americium silicides

International Nuclear Information System (INIS)

Wittmann, F.D.

1980-01-01

In order to take a closer look at the americium-silicon system, three further silicides of americium: Am 5 Si 3 , Am 2 Si 3 and AmSi 2 were prepared in addition to the already known americium monosilicide and starting from the knowledge gained from the latters preparation. Radiographic investigations were carried out into the temperature region of 900 0 C. They showed no change of structure in the three compounds. It was possible to prepare residue-free americium metal by reducing AmF 3 with Si, whereby the SiF 4 formed can be easily separated off as volatile compound, and the Am metal is brought into a very pure form by sublimation suitable for spectrochemical investigations. Attempts to prepare binary germanides and gallides of 241 americium were unsuccessful. (RB) [de
Burn-up analysis of uranium silicide fuels 20% 235U, in the LFR facility

International Nuclear Information System (INIS)

Amor, Ricardo A.; Bouza, Edgardo; Cabrejas, Julian L.; Devida, Claudio A.; Gil, Daniel A.; Stankevicius, Alejandro; Gautier, Eduardo; Garavaglia, Ricardo N.; Lobo, Alfredo

2003-01-01

The LFR Facility is a laboratory designed and constructed with a Hot-Cells line, a Globe-Box and a Fume-Hood, all of them suited to work with radioactive materials such as samples of irradiated silicide MTR fuel elements. A series of dissolutions of this material was performed. From the resulting solutions, two fractions were separated by HPLC. One contained U + Pu, and other the fission product Nd. The concentrations of these elements were obtained by isotopic dilution and mass spectrometry (IDMS). It is concluded that this technique is very powerful and accurate when properly applied, and makes the validation of burn-up calculation codes possible. It is worth remarking the Lfr capacity to carry on different Research and Development (R + D) tasks in the Nuclear Fuel Cycle field. (author)
Characterization of titanium silicide thin films by X-ray diffraction techniques

International Nuclear Information System (INIS)

Morimoto, N.J.

1987-01-01

This thesis deals with characterization techniques of thin films by means of X-ray diffraction. This includes phase identification and residual stress, microstress and crystallite size calculations. The techniques developed were applied on the study of the titanium silicide formation obtained by means of Rapidy Thermal Processing (RTP) pf Ti films deposited on silicon substratum. The different phases were studied in relation with processing temperature and time in one and two anneling steps. The low resistivity TiSi 2 phase was observed for temperature of 700 0 C and higher. The experimental results indicate that the residual stress of TiSi 2 films doesn't vary significantly with the annealing conditions. On the other hand, the microstress is reduced with annealing time at 800 0 C, while the crystallite size is almost not affected. For the microstress and the crystallite size determination technique, two methods were implemented and compared. The Riella's method appeared to be very efficient, while the Gangulle's method seemed to be inadequate, because the results oscillate too much [pt
In situ atomic-level observation of the formation of platinum silicide at platinum-silicon oxide interfaces under electron irradiation

Directory of Open Access Journals (Sweden)

Takeshi Nagase

2018-05-01

Full Text Available In situ atomic-level observation of the formation of Pt2Si at Pt/SiOx interface by electronic excitation under electron irradiation was performed by using scanning transmission electron microscopy. Scanning of an electron-beam probe stimulates silicide formation at the Pt/SiOx interface; the change in the Pt column corresponding to Pt2Si formation with a crystallographic orientation of (001Pt//(001Pt2Si and [110]Pt//[110]Pt2Si was observed in high-angle annular dark-field images.
Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

Energy Technology Data Exchange (ETDEWEB)

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

2017-12-19

Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.
Threshold Switchable Particles (TSP) to Control Internal Hemorrhage

Science.gov (United States)

2014-12-01

particle size. One method of preparing biocompatible iron oxide was to add poly( acrylic ) acid (PAA) to the particles’ surface. However, addition of...dense granules, and their resulting X-Ray microspectrum is quasi-identical, except for the presence of a small K peak. However, potassium was not...microspectrum is quasi-identical, except for the presence of a small K peak.18 However, potassium was not used here for PolyP nanoprecipitation
Iron Refractory Iron Deficiency Anaemia: A Rare Cause of Iron Deficiency Anaemia

LENUS (Irish Health Repository)

McGrath, T

2018-01-01

We describe the case of a 17-month-old boy with a hypochromic microcytic anaemia, refractory to oral iron treatment. After exclusion of dietary and gastrointestinal causes of iron deficiency, a genetic cause for iron deficiency was confirmed by finding two mutations in the TMPRSS6 gene, consistent with a diagnosis of iron-refractory iron deficiency anaemia (IRIDA).
The whole-core LEU silicide fuel demonstration in the JMTR

Energy Technology Data Exchange (ETDEWEB)

Aso, Tomokazu; Akashi, Kazutomo; Nagao, Yoshiharu [Japan Atomic Energy Research Institute, Ibaraki-ken (Japan)] [and others

1997-08-01

The JMTR was fully converted to LEU silicide (U{sub 3}Si{sub 2}) fuel with cadmium wires as burnable absorber in January, 1994. The reduced enrichment program for the JMTR was initiated in 1979, and the conversion to MEU (enrichment ; 45%) aluminide fuel was carried out in 1986 as the first step of the program. The final goal of the program was terminated by the present LEU conversion. This paper describes the results of core physics measurement through the conversion phase from MEU fuel core to LEU fuel core. Measured excess reactivities of the LEU fuel cores are mostly in good agreement with predicted values. Reactivity effect and burnup of cadmium wires, therefore, were proved to be well predicted. Control rod worth in the LEU fuel core is mostly less than that in the MEU fuel core. Shutdown margin was verified to be within the safety limit. There is no significant difference in temperature coefficient of reactivity between the MEU and LEU fuel cores. These results verified that the JMTR was successfully and safely converted to LEU fuel. Extension of the operating cycle period was achieved and reduction of spend fuel elements is expected by using the fuel with high uranium density.
Irradiation behavior of uranium-silicide dispersion fuels

International Nuclear Information System (INIS)

Hofman, G.L.; Neimark, L.A.

1984-01-01

This paper describes and analyzes the irradiation behavior of experimental fuel plates containing U 3 Si, U 3 Si-1.5 w/o Al, and U 3 Si 2 particulate fuel dispersed and clad in aluminum. The fuel is nominally 19.9%-enriched 235 U and the fuel volume fraction in the central ''meat'' section of the plates is approximately 33%. Sets of fuel plates were removed from the Oak Ridge Research reactor at burnup levels of 35, 83, and 94% 235 U depletion and examined at the Alpha-Gamma Hot-Cell Facility at Argonne National Laboratory. The results of the examination may be summarized as follows. The dimensional stability of the U 3 Si 2 and pure U 3 Si fuel was excellent throughout the entire burnup range, with uniform plate thickness increases up to a maximum of 4 mils at the highest burnup level (94% 235 U depletion). This corresponds to a meat volume increase of 11%. The swelling was partially due to solid fission products but to a larger extent to fission gas bubbles. The fission gas bubbles in U 3 Si 2 were small (submicrometer size) and very uniformly distributed, indicating great stability. To a large extent this was also the case for U 3 Si; however, larger bubbles ( 3 Si-1.5 w/o Al fuel became unstable at the higher burnup levels. Fission gas bubbles were larger than in the other two fuels and were present throughout the fuel particles. At 94% 235 U depletion, the formation of fission gas bubbles with diameters up to 20 mils caused the plates to pillow. It is proposed that aluminum in U 3 Si destabilizes fission gas bubble formation to the point of severe breakaway swelling in the prealloyed silicide fuel. (author)
Neutron irradiated uranium silicides studied by neutron diffraction and Rietveld analysis

International Nuclear Information System (INIS)

Birtcher, R.C.; Mueller, M.H.; Richardson, J.W. Jr.; Faber, J. Jr.

1989-11-01

Uranium silicides have been considered for use as reactor fuels in both high power and low enrichment applications. However, U 3 Si was found to become amorphous under irradiation and to become mechanically unstable to rapid growth by plastic flow. U 2 Si 2 appears to be stable against amorphization at low displacement rates, but the extent of this stability is uncertain. Although the mechanisms responsible for plastic flow in U 3 Si and other amorphous systems are unknown, as is the importance of crystal structure for amorphization, it may not be surprising that these materials amorphize, in light of the fact that many radioactive nuclide - containing minerals are known to metaminctize (lose crystallinity) under irradiation. The present experiment follows the detailed changes in the crystal structures of U 3 Si and U 3 Si 2 introduced by neutron bombardment and subsequent uranium fission at room temperature. U-Si seems the ideal system for a neutron diffraction investigation since the crystallographic and amorphous forms can be studied simultaneously by combining conventional Rietveld refinement of the crystallographic phases with Fourier-filtering of the non-crystalline scattering component
Prompt Neutron Decay Constant Determination Of Silicide Transition Core Using Noise Method

International Nuclear Information System (INIS)

Jujuratisbela, Uju; Yulianto, Yusi Eko; Cahyana

2001-01-01

Chairman of BATAN had decided to replace the Oxide fuel element type of RSG-GAS into silicide element type step by step. The replacement will create core transitions. Kinetic characteristic of the transition cores have to be monitored in order to know the deviation of core behavior. For that reason, the kinetic parameters have to be measured. Prompt neutron decay constant (alpha) is one of the kinetic parameters that has to be monitored continuously in the transition cores. In order not to disturb the normal operation of reactor, alpha parameter should be measured by using noise analysis method. The voltage of neutron flux at power of 15 MW is connected to preamplifier and filter then to the Dynamic Signal Analyzer Version-2 and then the auto power spectral density (APSD) was determined by using Fast Fourier transform. From the APSD curve of each channel of JKT03, the cut off frequency of each channel can be determined by using linear regression technique such that the prompt neutron decay constant can be estimated
Genetics Home Reference: iron-refractory iron deficiency anemia

Science.gov (United States)

... refractory iron deficiency anemia Iron-refractory iron deficiency anemia Printable PDF Open All Close All Enable Javascript ... expand/collapse boxes. Description Iron-refractory iron deficiency anemia is one of many types of anemia , which ...
Effect of dietary iron source and iron status on iron bioavailability tests in the rat

International Nuclear Information System (INIS)

Zhang, D.; Hendricks, D.G.; Mahoney, A.W.

1986-01-01

Weanling male rats were made anemic in 7 days by feeding a low iron diet and bleeding. Healthy rats were fed the low iron diet supplemented with ferrous sulfate (29 ppm Fe). Each group was subdivided and fed for 10 days on test diets containing about 29 ppm iron that were formulated with meat:spinach mixtures or meat:soy mixtures to provided 100:0, 75:25, 50:50, 25:75, or 0:100% of the dietary iron from these sources or from a ferrous sulfate diet. After 3 days on the diets all rats were dosed orally with 2 or 5 micro curries of 59 Fe after a 18 hour fast and refeeding for 1.5 hours. Iron status influenced liver iron, carcass iron, liver radio activity and percent of radioactive dose retained. Diet influenced fecal iron and apparent absorption of iron. In iron bioavailability studies assessment methodology and iron status of the test subject greatly influences the estimates of the value of dietary sources of iron
Iron absorption in relation to iron status

International Nuclear Information System (INIS)

Magnusson, B.; Bjoern-Rasmussen, E.; Hallberg, L.; Rossander, L.

1981-01-01

The absorption from a 3 mg dose of ferrous iron was measured in 250 male subjects. The absorption was related to the log concentration of serum ferritin in 186 subjects of whom 99 were regular blood donors (r= -0.76), and to bone marrow haemosiderin grading in 52 subjects with varying iron status. The purpose was to try and establish a percentage absorption from such a dose that is representative of subjects who are borderline iron deficient. This information is necessary for food iron absorption studies in order (1) to calculate the absorption of iron from the diet at a given iron status and (2) compare the absorption of iron from different meals studied in different groups of subjects by different investigarors. The results suggest that an absorption of about 40% of a 3 mg reference dose of ferrous iron is given in a fasting state, roughly corresponds to the absorption in borderline-iron-deficient subjects. The results indicate that this 40% absorption value corresponds to a serum ferritin level of 30 μg/l and that food iron absorption in a group of subjects should be expressed preferably as the absorption corresponding to a reference-dose absorption of 45%, or possibly a serum ferritin level of 30 μg/l. (author)
An iron-57 Moessbauer spectroscopic study of titania-supported iron- and iron-iridium catalysts

International Nuclear Information System (INIS)

Berry, F.J.; Jobson, S.

1992-01-01

57 Fe Moessbauer spectroscopy shows that titania-supported iron is reduced by treatment in hydrogen at significantly lower temperatures than corresponding silica- and alumina-supported catalysts. The metallic iron formed under hydrogen at 600deg C is partially converted to carbide by treatment in carbon monoxide and hydrogen. In contrast to its alumina- and silica-supported counterparts, the remainder of the titania-supported iron is unchanged by this gaseous mixture. The 57 Fe Moessbauer spectra of EXAFS show that iron and iridium in the titania-supported iron-iridium catalysts are reduced in hydrogen at even lower temperatures and, after treatment at 600deg C, are predominantly present as the iron-iridium alloy. The treatment of these reduced catalysts in carbon monoxide and hydrogen is shown by Moessbauer spectroscopy and EXAFS to induce the segregation of iron from the iron-iridium alloy and its conversion to iron oxide. (orig.)
Simulated Fission Gas Behavior in Silicide Fuel at LWR Conditions

Energy Technology Data Exchange (ETDEWEB)

Miao, Yinbin [Argonne National Lab. (ANL), Argonne, IL (United States); Mo, Kun [Argonne National Lab. (ANL), Argonne, IL (United States); Yacout, Abdellatif [Argonne National Lab. (ANL), Argonne, IL (United States); Harp, Jason [Argonne National Lab. (ANL), Argonne, IL (United States)

2016-09-15

As a promising candidate for the accident tolerant fuel (ATF) used in light water reactors (LWRs), the fuel performance of uranium silicide (U₃Si₂) at LWR conditions needs to be well-understood. However, existing experimental post-irradiation examination (PIE) data are limited to the research reactor conditions, which involve lower fuel temperature compared to LWR conditions. This lack of appropriate experimental data significantly affects the development of fuel performance codes that can precisely predict the microstructure evolution and property degradation at LWR conditions, and therefore evaluate the qualification of U₃Si₂ as an AFT for LWRs. Considering the high cost, long timescale, and restrictive access of the in-pile irradiation experiments, this study aims to utilize ion irradiation to simulate the inpile behavior of the U₃Si₂ fuel. Both in situ TEM ion irradiation and ex situ high-energy ATLAS ion irradiation experiments were employed to simulate different types of microstructure modifications in U₃Si₂. Multiple PIE techniques were used or will be used to quantitatively analyze the microstructure evolution induced by ion irradiation so as to provide valuable reference for the development of fuel performance code prior to the availability of the in-pile irradiation data.
Higher iron bioavailability of a human-like collagen iron complex.

Science.gov (United States)

Zhu, Chenhui; Yang, Fan; Fan, Daidi; Wang, Ya; Yu, Yuanyuan

2017-07-01

Iron deficiency remains a public health problem around the world due to low iron intake and/or bioavailability. FeSO 4 , ferrous succinate, and ferrous glycinate chelate are rich in iron but have poor bioavailability. To solve the problem of iron deficiency, following previous research studies, a thiolated human-like collagen-ironcomplex supplement with a high iron content was prepared in an anaerobic workstation. In addition, cell viability tests were evaluated after conducting an MTT assay, and a quantitative analysis of the thiolated human-like collagen-iron digesta samples was performed using the SDS-PAGE method coupled with gel filtration chromatography. The iron bioavailability was assessed using Caco-2 cell monolayers and iron-deficiency anemia mice models. The results showed that (1) one mole of thiolated human-like collagen-iron possessed approximately 35.34 moles of iron; (2) thiolated human-like collagen-iron did not exhibit cytotoxity and (3) thiolated human-like collagen- iron digesta samples had higher bioavailability than other iron supplements, including FeSO 4 , ferrous succinate, ferrous glycine chelate and thiolated human-like collagen-Fe iron. Finally, the iron bioavailability was significantly enhanced by vitamin C. These results indicated that thiolated human-like collagen-iron is a promising iron supplement for use in the future.

Status of core conversion with LEU silicide fuel in JRR-4

Energy Technology Data Exchange (ETDEWEB)

Nakajima, Teruo; Ohnishi, Nobuaki; Shirai, Eiji [Japan Atomic Energy Research Institute, Ibaraki-ken (Japan)

1997-08-01

Japan Research Reactor No.4 (JRR-4) is a light water moderated and cooled, 93% enriched uranium ETR-type fuel used and swimming pool type reactor with thermal output of 3.5MW. Since the first criticality was achieved on January 28, 1965, JRR-4 has been used for shielding experiments, radioisotope production, neutron activation analyses, training for reactor engineers and so on for about 30 years. Within the framework of the RERTR Program, the works for conversion to LEU fuel are now under way, and neutronic and thermal-hydraulic calculations emphasizing on safety and performance aspects are being carried out. The design and evaluation for the core conversion are based on the Guides for Safety Design and Evaluation of research and testing reactor facilities in Japan. These results show that the JRR-4 will be able to convert to use LEU fuel without any major design change of core and size of fuel element. LEU silicide fuel (19.75%) will be used and maximum neutron flux in irradiation hole would be slightly decreased from present neutron flux value of 7x10{sup 13}(n/cm{sup 2}/s). The conversion works are scheduled to complete in 1998, including with upgrade of the reactor building and utilization facilities.
Status of core conversion with LEU silicide fuel in JRR-4

International Nuclear Information System (INIS)

Nakajima, Teruo; Ohnishi, Nobuaki; Shirai, Eiji

1997-01-01

Japan Research Reactor No.4 (JRR-4) is a light water moderated and cooled, 93% enriched uranium ETR-type fuel used and swimming pool type reactor with thermal output of 3.5MW. Since the first criticality was achieved on January 28, 1965, JRR-4 has been used for shielding experiments, radioisotope production, neutron activation analyses, training for reactor engineers and so on for about 30 years. Within the framework of the RERTR Program, the works for conversion to LEU fuel are now under way, and neutronic and thermal-hydraulic calculations emphasizing on safety and performance aspects are being carried out. The design and evaluation for the core conversion are based on the Guides for Safety Design and Evaluation of research and testing reactor facilities in Japan. These results show that the JRR-4 will be able to convert to use LEU fuel without any major design change of core and size of fuel element. LEU silicide fuel (19.75%) will be used and maximum neutron flux in irradiation hole would be slightly decreased from present neutron flux value of 7x10 13 (n/cm 2 /s). The conversion works are scheduled to complete in 1998, including with upgrade of the reactor building and utilization facilities
Oxidation behavior of niobium aluminide intermetallics protected by aluminide and silicide diffusion coatings

International Nuclear Information System (INIS)

Li, Y.; Soboyejo, W.; Rapp, R.A.

1999-01-01

The isothermal and cyclic oxidation behavior of a new class of damage-tolerant niobium aluminide (Nb 3 Al-xTi-yCr) intermetallics is studied between 650 C and 850 C. Protective diffusion coatings were deposited by pack cementation to achieve the siliciding or aluminizing of substrates with or without intervening Mo or Ni layers, respectively. The compositions and microstructures of the resulting coatings and oxidized surfaces were characterized. The isothermal and cyclic oxidation kinetics indicate that uncoated Nb-40Ti-15Al-based intermetallics may be used up to ∼750 C. Alloying with Cr improves the isothermal oxidation resistance between 650 C and 850 C. The most significant improvement in oxidation resistance is achieved by the aluminization of electroplated Ni interlayers. The results suggest that the high-temperature limit of niobium aluminide-based alloys may be increased to 800 C to 850 C by aluminide-based diffusion coatings on ductile Ni interlayers. Indentation fracture experiments also indicate that the ductile nickel interlayers are resistant to crack propagation in multilayered aluminide-based coatings
FY 1997 report on the improvement of toughness of silicide system intermetallic compounds by complex texture; 1997 nendo chosa hokokusho (fukugo soshikika ni yoru silicide kei kinzokukan kagobutsu no kyojinsei kaizen)

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

In order to develop new materials superior in both room- temperature ductility and high-temperature strength, the basic data on MoSi2 intermetallic compounds with complex texture were stored. Intermetallic compound is one of the promising candidates of new super heat-resistant materials superior to conventional super heat-resistant alloys, however, it is extremely poor in ductility at room temperature. Based on available information on isothermal sectional phase diagrams of ternary system (Mo-Si-X system) composed of Mo silicide and the third element (X), some alloy systems were selected in consideration of use of carbide and nitride stably existing as dispersed phase of deposits at high temperature. A knowledge on phase diagrams of ternary system specimens with various compositions was obtained through arc melting, X-ray diffraction and texture observation, and heat treatment conditions for obtaining target complex textures were also determined. Storage of the basic data suggested that improvement of the ductility is possible by forming fine texture through addition of the third element and teat treatment. 21 refs., 58 figs., 15 tabs.
Iron

Science.gov (United States)

Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...
A cascade of iron-containing proteins governs the genetic iron starvation response to promote iron uptake and inhibit iron storage in fission yeast.

Directory of Open Access Journals (Sweden)

Javier Encinar del Dedo

2015-03-01

Full Text Available Iron is an essential cofactor, but it is also toxic at high levels. In Schizosaccharomyces pombe, the sensor glutaredoxin Grx4 guides the activity of the repressors Php4 and Fep1 to mediate a complex transcriptional response to iron deprivation: activation of Php4 and inactivation of Fep1 leads to inhibition of iron usage/storage, and to promotion of iron import, respectively. However, the molecular events ruling the activity of this double-branched pathway remained elusive. We show here that Grx4 incorporates a glutathione-containing iron-sulfur cluster, alone or forming a heterodimer with the BolA-like protein Fra2. Our genetic study demonstrates that Grx4-Fra2, but not Fep1 nor Php4, participates not only in iron starvation signaling but also in iron-related aerobic metabolism. Iron-containing Grx4 binds and inactivates the Php4 repressor; upon iron deprivation, the cluster in Grx4 is probably disassembled, the proteins dissociate, and Php4 accumulates at the nucleus and represses iron consumption genes. Fep1 is also an iron-containing protein, and the tightly bound iron is required for transcriptional repression. Our data suggest that the cluster-containing Grx4-Fra2 heterodimer constitutively binds to Fep1, and upon iron deprivation the disassembly of the iron cluster between Grx4 and Fra2 promotes reverse metal transfer from Fep1 to Grx4-Fra2, and de-repression of iron-import genes. Our genetic and biochemical study demonstrates that the glutaredoxin Grx4 independently governs the Php4 and Fep1 repressors through metal transfer. Whereas iron loss from Grx4 seems to be sufficient to release Php4 and allow its nuclear accumulation, total or partial disassembly of the Grx4-Fra2 cluster actively participates in iron-containing Fep1 activation by sequestering its iron and decreasing its interaction with promoters.
Surface structure and electronic states of epitaxial β-FeSi.sub.2./sub.(100)/Si(001) thin films: Combined quantitative LEED, ab initio DFT, and STM study

Czech Academy of Sciences Publication Activity Database

Romanyuk, Olexandr; Hattori, K.; Someta, M.; Daimon, H.

2014-01-01

Roč. 90, č. 15 (2014), "155305-1"-"155305-9" ISSN 1098-0121 Grant - others:AVČR(CZ) M100101201; Murata Science Foundation(JP) Project n. 00295 Institutional support: RVO:68378271 Keywords : iron silicide * LEED I-V * DFT * STM * surface reconstruction * surface states Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014
Dietary iron intake, iron status, and gestational diabetes.

Science.gov (United States)

Zhang, Cuilin; Rawal, Shristi

2017-12-01

Pregnant women are particularly vulnerable to iron deficiency and related adverse pregnancy outcomes and, as such, are routinely recommended for iron supplementation. Emerging evidence from both animal and population-based studies, however, has raised potential concerns because significant associations have been observed between greater iron stores and disturbances in glucose metabolism, including increased risk of type 2 diabetes among nonpregnant individuals. Yet, the evidence is uncertain regarding the role of iron in the development of gestational diabetes mellitus (GDM), a common pregnancy complication which has short-term and long-term adverse health ramifications for both women and their children. In this review, we critically and systematically evaluate available data examining the risk of GDM associated with dietary iron, iron supplementation, and iron status as measured by blood concentrations of several indicators. We also discuss major methodologic concerns regarding the available epidemiologic studies on iron and GDM. © 2017 American Society for Nutrition.
Studies on the pathogenesis in iron deficiency anemia Part 1. Urinary iron excretion in iron deficiency anemia patients and rats in various iron states

OpenAIRE

中西,徳彦

1991-01-01

In the "iron excretion test" , urinary iron excretion after injection of saccharated iron oxide has been reported to be accelerated in relapsing idiopathic iron deficiency anemia. To determine the relevance of urinary iron excretion to clinical factors other than iron metabolism, 15 clinical parameters were evaluated. The serum creatinine level was positively and the serum albumin level was negatively correlated with urinary iron excretion, showing coefficients of r＝0.97,－0.86 respectively, a...
Development of new ORIGEN2 data library sets for research reactors with light water cooled oxide and silicide LEU (20 w/o) fuels based on JENDL-3.3 nuclear data

International Nuclear Information System (INIS)

Liem, Peng Hong; Sembiring, Tagor Malem

2013-01-01

Highlights: • We developed new ORIGEN2 data library sets for research reactors based on JENDL-3.3. • The sets cover oxide and silicide LEU fuels with meat density up to 4.74 g U/cm 3 . • Two kinds of data library sets are available: fuel region and non-fuel regions. • We verified the new data library sets with other codes. • We validated the new data library against a non-destructive test. -- Abstract: New sets of ORIGEN2 data library dedicated to research/testing reactors with light water cooled oxide and silicide LEU fuel plates based on JENDL-3.3 nuclear data were developed, verified and validated. The new sets are considered to be an extension of the most recent release of ORIGEN2.2UPJ code, i.e. the ORLIBJ33 library sets. The newly generated ORIGEN2 data library sets cover both oxide and silicide LEU fuels with fuel meat density range from 2.96 to 4.74 g U/cm 3 used in the present and future operation of the Indonesian 30 MWth RSG GAS research reactor. The new sets are expected applicable also for other research/testing reactors which utilize similar fuels or have similar neutron spectral indices. In addition to the traditional ORIGEN2 library sets for fuel depletion analyses in fuel regions, in the new data library sets, new ORIGEN2 library sets for irradiation/activation analyses were also prepared which cover all representative non-fuel regions of RSG GAS such as reflector elements, irradiation facilities, etc. whose neutron spectra are significantly softer than fuel regions. Verification with other codes as well as validation with a non-destructive test result showed promising results where a good agreement was confirmed
Iron from Zealandic bog iron ore -

DEFF Research Database (Denmark)

Lyngstrøm, Henriette Syrach

2011-01-01

og geologiske materiale, metallurgiske analyser og eksperimentel arkæologiske forsøg - konturerne af en jernproduktion med udgangspunkt i den sjællandske myremalm. The frequent application by archaeologists of Werner Christensen’s distribution map for the occurrence of bog iron ore in Denmark (1966...... are sketched of iron production based on bog iron ore from Zealand....
Radiation Re-solution Calculation in Uranium-Silicide Fuels

International Nuclear Information System (INIS)

Matthews, Christopher; Andersson, Anders David Ragnar; Unal, Cetin

2017-01-01

The release of fission gas from nuclear fuels is of primary concern for safe operation of nuclear power plants. Although the production of fission gas atoms can be easily calculated from the fission rate in the fuel and the average yield of fission gas, the actual diffusion, behavior, and ultimate escape of fission gas from nuclear fuel depends on many other variables. As fission gas diffuses through the fuel grain, it tends to collect into intra-granular bubbles, as portrayed in Figure 1.1. These bubbles continue to grow due to absorption of single gas atoms. Simultaneously, passing fission fragments can cause collisions in the bubble that result in gas atoms being knocked back into the grain. This so called ''re-solution'' event results in a transient equilibrium of single gas atoms within the grain. As single gas atoms progress through the grain, they will eventually collect along grain boundaries, creating inter-granular bubbles. As the inter-granular bubbles grow over time, they will interconnect with other grain-face bubbles until a pathway is created to the outside of the fuel surface, at which point the highly pressurized inter-granular bubbles will expel their contents into the fuel plenum. This last process is the primary cause of fission gas release. From the simple description above, it is clear there are several parameters that ultimately affect fission gas release, including the diffusivity of single gas atoms, the absorption and knockout rate of single gas atoms in intra-granular bubbles, and the growth and interlinkage of intergranular bubbles. Of these, the knockout, or re-solution rate has an particularly important role in determining the transient concentration of single gas atoms in the grain. The re-solution rate will be explored in the following sections with regards to uranium-silicide fuels in order to support future models of fission gas bubble behavior.
Response to parenteral iron therapy distinguish unexplained refractory iron deficiency anemia from iron-refractory iron deficiency anemia.

Science.gov (United States)

Akin, M; Sarbay, H; Guler, S; Balci, Y I; Polat, A

2016-04-01

We evaluated that response to parenteral iron therapy could be helpful in distinguishing the types of iron deficiency anemia. This study analyzed responses to IV iron sucrose therapy of 15 children with unexplained refractory iron deficiency anemia (URIDA). We compared the results at diagnosis, 6 weeks and 6 months after the therapy. Results were compared with responses of 11 patients' results with iron-refractory iron deficiency anemia (IRIDA) from our previous study. Six weeks after the start of treatment, ferritin, MCV, MCH and Hb values were in normal range in 10 patients. The increase in Hb, MCH, MCV, and ferritin values ranged 2.6-3.5 g/dL, 1.7-4.2 pg, 2-9 fL, and 13-25 ng/mL, respectively. In five patients, Hb, MCH, and MCV mean (range) values [11.2 g/dL (11-12.2), 24.5 pg (24-25.6), and 67 fL (65-70)] were nearly normal but ferritin mean (range) values [9.8 ng/mL (8-11)] were below normal. Six weeks after the start of treatment, Hb, MCH, MCV and ferritin values of patients with IRIDA were increased. The increase in Hb, MCH, MCV, and ferritin values ranged 0.8-2.7 g/dL, 1.7-4.2 pg, 2-9 fL, and 13-25 ng/mL, respectively. IRIDA is only partially responsive to parenteral iron supplementation. In conclusion, this study demonstrated that the response to intravenous iron therapy for the URIDA cases improved blood parameters more effectively than hereditary IRIDA. Response to parenteral iron therapy would be helpful to distinguish unexplained refractory IDA from hereditary IRIDA for clinicians who do not have access to hepcidin or TMPRS6 mutation analysis. © 2016 John Wiley & Sons Ltd.
Leaching of aluminum and iron from boiler slag generated from a typical Chinese Steel Plant.

Science.gov (United States)

Li, Jinping; Gan, Jinhua; Li, Xianwang

2009-07-30

This paper presents a new way of recycling aluminum and iron in boiler slag derived from coal combustion plants, which integrates efficient extraction and reuse of the leached pellets together. The boiler slag was pelletized together with washed coal and lime prior to sintering and then was sintered at 800-1200 degrees C for different periods to produce sintered pellets for the leaching test. An elemental analysis of aqueous solutions leached by sulfuric acid was determined by EDTA-Na(2)-ZnCl(2) titration method. The components and microstructures of the samples, sintered pellets and leached residue were examined by means of XRF, XRD and SEM. XRD analysis indicates that predominate minerals such as kaolinite, quartz, calcium silicide, hematate and metakoalin exist in the boiler slag. An aluminum extraction efficiency of 86.50% was achieved. The maximum extraction efficiency of Fe was 94.60% in the same conditions of that for the maximum extraction efficiency of Al. The extraction efficiencies of Al and Fe increased with an increase in temperature, leaching time and acidity. High Al extraction efficiency was obtained for pellets with high CaO content. The final product of alumina would be used directly for the production of metallic aluminum.
Iron isomaltoside 1000: a new intravenous iron for treating iron deficiency in chronic kidney disease

DEFF Research Database (Denmark)

Wikström, Björn; Bhandari, Sunil; Barany, Peter

2011-01-01

Patients with chronic kidney disease (CKD) often suffer from iron deficiency anemia necessitating treatment with intravenous iron. This study was designed to assess the safety of iron isomaltoside 1000 (Monofer) in CKD patients. The secondary objective was to assess its effect on iron deficiency...... anemia....
The Effect Of Local Coal And Smelting Sponge Iron On Iron Content Of Pig Iron

Science.gov (United States)

Oediyani, Soesaptri; Juwita Sari, Pramita; Hadi P, Djoko

2018-03-01

The new regulation on mineral resources was announced by Ministry of Energy and Mineral resources (ESDM) of Indonesia at 2014 which it called Permen ESDM No 1/2014. Therefore, this research was conducted to add the value of local iron ores by using smelting technology. The objective of the research is to produce pig iron that meet the requirement of the new regulation of mineral resources such as 90% Fe. First, iron ores and coal mixed together with lime as a flux, then smelted in a Electric Arc Furnace at 1800°C. The process variables are (1; 1.25; 1.5; 1.75; 2.0) and the composition of coal (0.8%, 1.6%, 3.0%). The type of coal that used in this research was bituminous coal from Kalimantan and also the iron ores from Kalimantan. The products of the smelting technology are Pig iron and slag. Both pig iron and slag then analyzed by SEM-EDS to measure the iron content. The result shows that the maximum iron content on pig iron is about 95.04% meanwhile the minimum iron content on slag is about 3.66%. This result achieved at 1.6% coal and 2.0.
Iron biomineralization by anaerobic neutrophilic iron-oxidizing bacteria

DEFF Research Database (Denmark)

Miot, Jennyfer; Benzerara, Karim; Morin, Guillaume

2009-01-01

Minerals formed by bio-oxidation of ferrous iron (Fe(II)) at neutral pH, their association with bacterial ultrastructures as well as their impact on the metabolism of iron-oxidizing bacteria remain poorly understood. Here, we investigated iron biomineralization by the anaerobic nitrate-dependent ......Minerals formed by bio-oxidation of ferrous iron (Fe(II)) at neutral pH, their association with bacterial ultrastructures as well as their impact on the metabolism of iron-oxidizing bacteria remain poorly understood. Here, we investigated iron biomineralization by the anaerobic nitrate...... precipitation in the periplasm (in a few tens of minutes), followed by the formation of surface-bound globules. Moreover, we frequently observed an asymmetric mineral thickening at the cell poles. In parallel, the evolution of iron oxidation was quantified by STXM: iron both contained in the bacteria...... and in the extracellular precipitates reached complete oxidation within 6 days. While a progressive oxidation of Fe in the bacteria and in the medium could be observed, spatial redox (oxido-reduction state) heterogeneities were detected at the cell poles and in the extracellular precipitates after 1 day. All...
Microstructural characterization of atom clusters in irradiated pressure vessel steels and model alloys

International Nuclear Information System (INIS)

Auger, P.; Pareige, P.; Akamatsu, M.; Van Duysen, J.C.

1993-01-01

In order to characterize the microstructural evolution of iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions, and, for comparison, low copper model alloys irradiated with neutrons and electrons, have been studied through small angle neutron scattering and atom probe experiments. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex; solute atoms such as Ni, Mn and Si, sometimes associated with Cu, segregate as ''clouds'' more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs
Microstructural characterization of atom clusters in irradiated pressure vessel steels and model alloys

Energy Technology Data Exchange (ETDEWEB)

Auger, P; Pareige, P [Rouen Univ., 76 - Mont-Saint-Aignan (France); Akamatsu, M; Van Duysen, J C [Electricite de France (EDF), 77 - Ecuelles (France)

1994-12-31

In order to characterize the microstructural evolution of iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions, and, for comparison, low copper model alloys irradiated with neutrons and electrons, have been studied through small angle neutron scattering and atom probe experiments. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex; solute atoms such as Ni, Mn and Si, sometimes associated with Cu, segregate as ``clouds`` more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs.
46 CFR 56.60-10 - Cast iron and malleable iron.

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Cast iron and malleable iron. 56.60-10 Section 56.60-10... APPURTENANCES Materials § 56.60-10 Cast iron and malleable iron. (a) The low ductility of cast iron and malleable iron should be recognized and the use of these metals where shock loading may occur should be...

Multivariate analysis for the optimization of microfluidics-assisted nanoprecipitation method intended for the loading of small hydrophilic drugs into PLGA nanoparticles.

Science.gov (United States)

Chiesa, E; Dorati, R; Modena, T; Conti, B; Genta, I

2018-01-30

Design of Experiment-assisted evaluation of critical process (total flow rate, TFR, flow rate ratio, FRR) and formulation (polymer concentration and structure, drug:polymer ratio) variables in a novel microfluidics-based device, a staggered herringbone micromixer (SHM), for poly(lactic-co-glycolic acid) copolymer (PLGA) nanoparticles (NPs) manufacturing was performed in order to systematically evaluate and mathematically describe their effects on NPs sizes and drug encapsulation; a small hydrophilic moiety, N-acetylcysteine, was chosen as challenging model drug. SHM-assisted nanoprecipitation method consistently yielded NPs with tailor made sizes (in the range of 100-900 nm) and polydispersity index range from 0.061 to 0.286. Significant effects on NPs sizes were highlighted for TFR and FRR: increasing TFR (from 5 to 15 mL/min) and decreasing FRR (from 1:1 to 1:5 v/v, acetonitrile: buffer) NPs with mean diameter <200 nm were obtained. SHM technique allowed for flexible, application-specific tuning of PLGA NPs size using organic solvents with relatively low toxicity (acetone, acetonitrile), varying aqueous phase composition (Tris buffer vs PVA aqueous solution) and PLGA characteristics (Mw ranging from 25-90 kDa, capped or un-capped PLGA, different lactide:glycolide molar ratio). A very satisfactory N-Ac encapsulation efficiency (more than 67%) and a prolonged release (by 168 h) were achieved. Copyright © 2017 Elsevier B.V. All rights reserved.
Quantification of body iron and iron absorption in the REDS-II Donor Iron Status Evaluation (RISE) study.

Science.gov (United States)

Kiss, Joseph E; Birch, Rebecca J; Steele, Whitney R; Wright, David J; Cable, Ritchard G

2017-07-01

Repeated blood donation alters the iron balance of blood donors. We quantified these effects by analyzing changes in body iron as well as calculating iron absorbed per day for donors enrolled in a prospective study. For 1308 donors who completed a final study visit, we calculated total body iron at the enrollment and final visits and the change in total body iron over the course of the study. Taking into account iron lost from blood donations during the study and obligate losses, we also calculated the average amount of iron absorbed per day. First-time/reactivated donors at enrollment had iron stores comparable to previous general population estimates. Repeat donors had greater donation intensity and greater mean iron losses than first-time/reactivated donors, yet they had little change in total body iron over the study period, whereas first-time/reactivated donors had an average 35% drop. There was higher estimated iron absorption in the repeat donors (men: 4.49 mg/day [95% confidence interval [CI], 4.41-4.58 mg/day]; women: 3.75 mg/day [95% CI, 3.67-3.84 mg/day]) compared with estimated iron absorption in first-time/reactivated donors (men: 2.89 mg/day [95% CI, 2.75-3.04 mg/day]; women: 2.76 mg/day [95% CI, 2.64-2.87 mg/day]). The threshold for negative estimated iron stores (below "0" mg/kg stores) was correlated with the development of anemia at a plasma ferritin value of 10 ng/mL. These analyses provide quantitative data on changes in estimated total body iron for a broad spectrum of blood donors. In contrast to using ferritin alone, this model allows assessment of the iron content of red blood cells and the degree of both iron surplus and depletion over time. © 2017 AABB.
The Comparison Of Silicon Analysis For The Uranium Silicide Fuel Using Spectrophotometrical And Gravimetrical Methods

International Nuclear Information System (INIS)

Putro, P. K.; Suripto, A.; Putra, S.; Gunanjar

1996-01-01

The analysis of silicon content in the uranium silicide fuel spectro-photometrical and gravimetrical method have been performed. The nitrous oxide-acetylene was used in the atomic absorption spectrophotometry (AAS) on the wave length of 251.6 nm, and the mixture of ammonium hepta molybdate complexes and SnC1 2 as reductor were applied during analysis by UV-VIS spectrophotometry (UV-VIS) on the wave length of 757.5 mm. The reagent of HCLO 4 and HNO 3 were used for determining Si content by gravimetrical methods. The results of this comparison is as follows: the accuracy result is around 96.37 % + 0.24 % for the Si concentration up to 300 ppm (the AAS), is 138.60 % = 0.43 % for the Si concentration range between 0.1-1.5 ppm (UV-VIS), and is 51.13 % + 0.8 % for 1 gram of Si (gravimetry). The results also show that the lowest analytical error is obtained by AAS method
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... Research Home / < Back To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español Iron-deficiency ... iron-deficiency anemia. Blood tests to screen for iron-deficiency anemia To screen for iron-deficiency anemia, your doctor ...
49 CFR 192.373 - Service lines: Cast iron and ductile iron.

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Cast iron and ductile iron. 192.373... Regulators, and Service Lines § 192.373 Service lines: Cast iron and ductile iron. (a) Cast or ductile iron... cast iron pipe or ductile iron pipe is installed for use as a service line, the part of the service...
Analysis of gamma dose for 4,8 gU/cm3 density silicide core at the RSG-GAS reactor using MCNP code

International Nuclear Information System (INIS)

Ardani

2011-01-01

Radiation safety analysis should be done following of substitution of fuel density of 2.96 gU/cc to density of 4,8 gU/cc silicide fuels for the RSG-GAS reactor. MCNP-5 code has been used to perform gamma dose calculation of the RSG-GAS reactor. Gamma radiation source at reactor consists of capture gamma rays, prompt fission gamma rays, and gamma rays of decay of fission and activation products. The strength of the prompt fission gamma rays is obtained by gamma releases of fission process of U-235 and reactor power of 30 MWt., during 46,6 days operation. Radiation dose is calculated at the experimental hall by detection point at the surface of outer of biological shielding and the operation hall by detection point at the top of the pool. The calculation is conducted at reactor on the normal operation and on the worst postulated accident causing the water level at the pool decreases. Calculation result shows that the biggest source strength of gamma rays come from the decay process. The highest calculated dose at the experiment hall is 4,07x10 -3 μSv/h, far from the maximum external dose permitted 25 μSv/h. The highest calculated dose at the operation hall is 19.98 μSv/h. Even though the calculated dose is still acceptable but this is close to the maximum permitted dose for worker. It concluded that loading of 4,8 gU/cc silicide fuel for the RSG-GAS still safe. (author)
Comparative study of efficacy, tolerability and compliance of oral iron preparations (iron edetate, iron polymatose complex) and intramuscular iron sorbitol in iron deficiency anaemia in children

International Nuclear Information System (INIS)

Afzal, M.; Qureshi, S.M.; Lutafullah, M.

2009-01-01

To compare the efficacy, tolerability and compliance of oral iron preparations(iron edetate and Iron polymaltose complex) with each other and with intramuscular iron sorbitol in iron deficiency anaemia in children. A Randomized Controlled Trial (RCT) was carried out at the Paediatric Department of Combined Military Hospital (CMH) from January 2006 to December 2007. In total 146 children, up to 12 years age having haemoglobin (Hb%) less than 8 gm% were included. They were randomly distributed into three groups. Group A(64 cases) received oral sodium iron edetate (SIE), Group B (40 cases) received oral iron polymaltose complex (IPC) and group C (42 cases) received intramuscular iron sorbitol (IS) in recommended dosages. Rise in Hb%>10 gm% was kept as desired target. Maximum duration of treatment planned was 2 weeks for parenteral iron (group C) and 12 weeks for oral iron (groups A and B). Haematological parameters- Hb%, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) were measured at induction followed at 2 weeks, 4 weeks, 8 weeks and 12 weeks after start of treatment. Compliance and drop out rates were determined on each visit. Data was analyzed using SPSS version 10. ANOVA was used to analyze difference in rise in Hb% at various intervals. Statistically significant increase in mean Hb%, MCV, MCHC after 02 weeks was observed in group C (IS). Rise in these parameters became significant in group A (SIE) and B (IPC) after 04 weeks. Persistent rise was observed in oral groups at 08 and 12 weeks. Rise in Hb% was much faster in group C (IS). It took 2 weeks to achieve mean Hb% > 10 gm% and compliance rate was 40.5%, while to achieve same target, duration required was 8 weeks in group A (SIE) and 12 weeks in group B (IPC) and compliance rate was 39% and 30% respectively. Adverse effects were much more common with group A (SIE) as compared to other two groups. Intramuscular iron sorbitol is a reliable and
Results of the First American Prospective Study of Intravenous Iron in Oral Iron-Intolerant Iron-Deficient Gravidas.

Science.gov (United States)

Auerbach, Michael; James, Stephanie E; Nicoletti, Melissa; Lenowitz, Steven; London, Nicola; Bahrain, Huzefa F; Derman, Richard; Smith, Samuel

2017-12-01

Anemia affects up to 42% of gravidas. Neonatal iron deficiency is associated with low birth weight, delayed growth and development, and increased cognitive and behavioral abnormalities. While oral iron is convenient, up to 70% report significant gastrointestinal toxicity. Intravenous iron formulations allowing replacement in one visit with favorable side-effect profiles decrease rates of anemia with improved hemoglobin responses and maternal fetal outcomes. Seventy-four oral iron-intolerant, second- and third-trimester iron-deficient gravidas were questioned for oral iron intolerance and treated with intravenous iron. All received 1000 mg of low-molecular-weight iron dextran in 250 mL normal saline. Fifteen minutes after a test dose, the remainder was infused over the balance of 1 hour. Subjects were called at 1, 2, and 7 days to assess delayed reactions. Four weeks postinfusion or postpartum, hemoglobin levels and iron parameters were measured. Paired t test was used for hemoglobin and iron; 58/73 women were questioned about interval growth and development of their babies. Seventy-three of 74 enrolled subjects completed treatment. Sixty had paired pre- and posttreatment data. The mean pre- and posthemoglobin concentrations were 9.7 and 10.8 g/dL (P iron deficiency anemia. Intravenous iron has less toxicity and is more effective, supporting moving it closer to frontline therapy. Copyright © 2017 Elsevier Inc. All rights reserved.
Studying Irony Detection Beyond Ironic Criticism: Let's Include Ironic Praise

Directory of Open Access Journals (Sweden)

Richard Bruntsch

2017-04-01

Full Text Available Studies of irony detection have commonly used ironic criticisms (i.e., mock positive evaluation of negative circumstances as stimulus materials. Another basic type of verbal irony, ironic praise (i.e., mock negative evaluation of positive circumstances is largely absent from studies on individuals' aptitude to detect verbal irony. However, it can be argued that ironic praise needs to be considered in order to investigate the detection of irony in the variety of its facets. To explore whether the detection ironic praise has a benefit beyond ironic criticism, three studies were conducted. In Study 1, an instrument (Test of Verbal Irony Detection Aptitude; TOVIDA was constructed and its factorial structure was tested using N = 311 subjects. The TOVIDA contains 26 scenario-based items and contains two scales for the detection of ironic criticism vs. ironic praise. To validate the measurement method, the two scales of the TOVIDA were experimentally evaluated with N = 154 subjects in Study 2. In Study 3, N = 183 subjects were tested to explore personality and ability correlates of the two TOVIDA scales. Results indicate that the co-variance between the ironic TOVIDA items was organized by two inter-correlated but distinct factors: one representing ironic praise detection aptitude and one representing ironic criticism detection aptitude. Experimental validation showed that the TOVIDA items truly contain irony and that item scores reflect irony detection. Trait bad mood and benevolent humor (as a facet of the sense of humor were found as joint correlates for both ironic criticism and ironic praise detection scores. In contrast, intelligence, trait cheerfulness, and corrective humor were found as unique correlates of ironic praise detection scores, even when statistically controlling for the aptitude to detect ironic criticism. Our results indicate that the aptitude to detect ironic praise can be seen as distinct from the aptitude to detect ironic
Large-format platinum silicide microwave kinetic inductance detectors for optical to near-IR astronomy.

Science.gov (United States)

Szypryt, P; Meeker, S R; Coiffard, G; Fruitwala, N; Bumble, B; Ulbricht, G; Walter, A B; Daal, M; Bockstiegel, C; Collura, G; Zobrist, N; Lipartito, I; Mazin, B A

2017-10-16

We have fabricated and characterized 10,000 and 20,440 pixel Microwave Kinetic Inductance Detector (MKID) arrays for the Dark-speckle Near-IR Energy-resolved Superconducting Spectrophotometer (DARKNESS) and the MKID Exoplanet Camera (MEC). These instruments are designed to sit behind adaptive optics systems with the goal of directly imaging exoplanets in a 800-1400 nm band. Previous large optical and near-IR MKID arrays were fabricated using substoichiometric titanium nitride (TiN) on a silicon substrate. These arrays, however, suffered from severe non-uniformities in the TiN critical temperature, causing resonances to shift away from their designed values and lowering usable detector yield. We have begun fabricating DARKNESS and MEC arrays using platinum silicide (PtSi) on sapphire instead of TiN. Not only do these arrays have much higher uniformity than the TiN arrays, resulting in higher pixel yields, they have demonstrated better spectral resolution than TiN MKIDs of similar design. PtSi MKIDs also do not display the hot pixel effects seen when illuminating TiN on silicon MKIDs with photons with wavelengths shorter than 1 µm.
Analysis Of Temperature Effects On Reactivity Of The Rsg-Gas Core Using Silicide Fuels

International Nuclear Information System (INIS)

Surbakti, Tukiran; Pinem, Surian

2001-01-01

RSG-GAS has been operating using new silicide fuels so that it is necessary to estimate and to measure the effect of temperature on reactivity of the core. The parameters to be determined due to temperature effect are reactivity coefficient of moderator temperature, temperature coefficient of fuel element and power reactivity coefficient. By doing a couple compensation method, determination of reactivity coefficient as well as the reactivity coefficient of moderator temperature can be obtained. Furthermore, coefficient of the reactivity was successfully estimated using the combination of WIMS-D4 and Batan-2DIFF. The cell calculation was done by using WIMS-D4 code to get macroscopic cross section and Batan-2DIFF code is used for core calculation. The calculation and experimental results of reactivity coefficient do not show any deviation from RSG-GAS safety margin. The results are -2,84 sen/ o C, -1,29 sen/MW and -0,64 sen/ o C for reactivity coefficients of temperature, power, fuel element and moderator temperature, respectively. All of 3 parameters are absolutely met with safety criteria
Absorption of medicamental iron and iron from food

International Nuclear Information System (INIS)

Reizenstein, P.; Carlmark, B.; Ehn, L.; Forsberg, K.; Hoeglund, S.; Terpstra, T.

1976-01-01

Methods are reviewed for the measurement of iron absorption. The chemical balance method has been almost entirely supplanted by radioisotope methods, which include notably whole-body counting and measurement of incorporation of radioiron into red cells. A survey is also given of the various conditions that influence iron absorption, including chemical form of iron, amount of iron, accompanying diet. Absorption tests must be conducted under relevant conditions. (author)
Iron-Deficiency Anemia

Science.gov (United States)

... To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español Iron-deficiency ... anemia. Blood tests to screen for iron-deficiency anemia To screen for iron-deficiency anemia, your doctor ...
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... risk for iron-deficiency anemia, including: Vegetarian or vegan eating patterns. Not eating enough iron-rich foods, ... iron-fortified foods that have iron added. Vegetarian diets can provide enough iron if you choose nonmeat ...
Reactivity management and burn-up management on JRR-3 silicide-fuel-core

International Nuclear Information System (INIS)

Kato, Tomoaki; Araki, Masaaki; Izumo, Hironobu; Kinase, Masami; Torii, Yoshiya; Murayama, Yoji

2007-08-01

On the conversion from uranium-aluminum-dispersion-type fuel (aluminide fuel) to uranium-silicon-aluminum-dispersion-type fuel (silicide fuel), uranium density was increased from 2.2 to 4.8 g/cm 3 with keeping uranium-235 enrichment of 20%. So, burnable absorbers (cadmium wire) were introduced for decreasing excess reactivity caused by the increasing of uranium density. The burnable absorbers influence reactivity during reactor operation. So, the burning of the burnable absorbers was studied and the influence on reactor operation was made cleared. Furthermore, necessary excess reactivity on beginning of operation cycle and the time limit for restart after unplanned reactor shutdown was calculated. On the conversion, limit of fuel burn-up was increased from 50% to 60%. And the fuel exchange procedure was changed from the six-batch dispersion procedure to the fuel burn-up management procedure. The previous estimation of fuel burn-up was required for the planning of fuel exchange, so that the estimation was carried out by means of past operation data. Finally, a new fuel exchange procedure was proposed for effective use of fuel elements. On the procedure, burn-up of spent fuel was defined for each loading position. The average length of fuel's staying in the core can be increased by two percent on the procedure. (author)
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español Iron-deficiency anemia is a ... address the cause of your iron deficiency, such as any underlying bleeding. If undiagnosed or untreated, iron- ...
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español Iron-deficiency ... anemia. Blood tests to screen for iron-deficiency anemia To screen for iron-deficiency anemia, your doctor ...
Serum iron and total iron binding capacity levels among the abo ...

African Journals Online (AJOL)

Iron deficiency anaemia is a common tropical disease. Iron plays a very important role in the human body. The understanding of the different blood groups ability to retain iron in their system can give an insight into their ability to handle the disease Iron deficiency anaemia. Serum Iron, Total Iron Binding Capacity (TIBC) and ...
Zinc deficiency-induced iron accumulation, a consequence of alterations in iron regulatory protein-binding activity, iron transporters, and iron storage proteins.

Science.gov (United States)

Niles, Brad J; Clegg, Michael S; Hanna, Lynn A; Chou, Susan S; Momma, Tony Y; Hong, Heeok; Keen, Carl L

2008-02-22

One consequence of zinc deficiency is an elevation in cell and tissue iron concentrations. To examine the mechanism(s) underlying this phenomenon, Swiss 3T3 cells were cultured in zinc-deficient (D, 0.5 microM zinc), zinc-supplemented (S, 50 microM zinc), or control (C, 4 microM zinc) media. After 24 h of culture, cells in the D group were characterized by a 50% decrease in intracellular zinc and a 35% increase in intracellular iron relative to cells in the S and C groups. The increase in cellular iron was associated with increased transferrin receptor 1 protein and mRNA levels and increased ferritin light chain expression. The divalent metal transporter 1(+)iron-responsive element isoform mRNA was decreased during zinc deficiency-induced iron accumulation. Examination of zinc-deficient cells revealed increased binding of iron regulatory protein 2 (IRP2) and decreased binding of IRP1 to a consensus iron-responsive element. The increased IRP2-binding activity in zinc-deficient cells coincided with an increased level of IRP2 protein. The accumulation of IRP2 protein was independent of zinc deficiency-induced intracellular nitric oxide production but was attenuated by the addition of the antioxidant N-acetylcysteine or ascorbate to the D medium. These data support the concept that zinc deficiency can result in alterations in iron transporter, storage, and regulatory proteins, which facilitate iron accumulation.
Mammalian iron metabolism and its control by iron regulatory proteins☆

Science.gov (United States)

Anderson, Cole P.; Shen, Lacy; Eisenstein, Richard S.; Leibold, Elizabeth A.

2013-01-01

Cellular iron homeostasis is maintained by iron regulatory proteins 1 and 2 (IRP1 and IRP2). IRPs bind to iron-responsive elements (IREs) located in the untranslated regions of mRNAs encoding protein involved in iron uptake, storage, utilization and export. Over the past decade, significant progress has been made in understanding how IRPs are regulated by iron-dependent and iron-independent mechanisms and the pathological consequences of IRP2 deficiency in mice. The identification of novel IREs involved in diverse cellular pathways has revealed that the IRP–IRE network extends to processes other than iron homeostasis. A mechanistic understanding of IRP regulation will likely yield important insights into the basis of disorders of iron metabolism. This article is part of a Special Issue entitled: Cell Biology of Metals. PMID:22610083

Iron-binding haemerythrin RING ubiquitin ligases regulate plant iron responses and accumulation

Science.gov (United States)

Kobayashi, Takanori; Nagasaka, Seiji; Senoura, Takeshi; Itai, Reiko Nakanishi; Nakanishi, Hiromi; Nishizawa, Naoko K.

2013-01-01

Iron is essential for most living organisms. Plants transcriptionally induce genes involved in iron acquisition under conditions of low iron availability, but the nature of the deficiency signal and its sensors are unknown. Here we report the identification of new iron regulators in rice, designated Oryza sativa Haemerythrin motif-containing Really Interesting New Gene (RING)- and Zinc-finger protein 1 (OsHRZ1) and OsHRZ2. OsHRZ1, OsHRZ2 and their Arabidopsis homologue BRUTUS bind iron and zinc, and possess ubiquitination activity. OsHRZ1 and OsHRZ2 are susceptible to degradation in roots irrespective of iron conditions. OsHRZ-knockdown plants exhibit substantial tolerance to iron deficiency, and accumulate more iron in their shoots and grains irrespective of soil iron conditions. The expression of iron deficiency-inducible genes involved in iron utilization is enhanced in OsHRZ-knockdown plants, mostly under iron-sufficient conditions. These results suggest that OsHRZ1 and OsHRZ2 are iron-binding sensors that negatively regulate iron acquisition under conditions of iron sufficiency. PMID:24253678
Extracting phosphoric iron under laboratorial conditions smelting bog iron ores

International Nuclear Information System (INIS)

Török, B; Thiele, A

2013-01-01

In recent years it has been indicated by archaeometric investigations that phosphoric-iron (P-iron, low carbon steel with 0,5-1,5wt% P), which is an unknown and unused kind of steel in the modern industry, was widely used in different parts of the world in medieval times. In this study we try to explore the role of phosphorus in the arhaeometallurgy of iron and answer some questions regarding the smelting bog iron ores with high P-content. XRF analyses were performed on bog iron ores collected in Somogy county. Smelting experiments were carried out on bog iron ores using a laboratory model built on the basis of previously conducted reconstructed smelting experiments in copies of excavated furnaces. The effect of technological parameters on P-content of the resulted iron bloom was studied. OM and SEM-EDS analyses were carried out on the extracted iron and slag samples. On the basis of the material analyses it can be stated that P-iron is usually extracted but the P-content is highly affected by technological parameters. Typical microstructures of P-iron and of slag could also be identified. It could also be established that arsenic usually solved in high content in iron as well
Iron Therapy in Patients with Heart Failure and Iron Deficiency: Review of Iron Preparations for Practitioners.

Science.gov (United States)

Drozd, Marcin; Jankowska, Ewa A; Banasiak, Waldemar; Ponikowski, Piotr

2017-06-01

In patients with heart failure (HF), iron deficiency (ID) correlates with decreased exercise capacity and poor health-related quality of life, and predicts worse outcomes. Both absolute (depleted iron stores) and functional (where iron is unavailable for dedicated tissues) ID can be easily evaluated in patients with HF using standard laboratory tests (assessment of serum ferritin and transferrin saturation). Intravenous iron therapy in iron-deficient patients with HF and reduced ejection fraction has been shown to alleviate HF symptoms and improve exercise capacity and quality of life. In this paper, we provide information on how to diagnose ID in HF. Further we discuss pros and cons of different iron preparations and discuss the results of major trials implementing iron supplementation in HF patients, in order to provide practical guidance for clinicians on how to manage ID in patients with HF.
Siderophore-mediated iron trafficking in humans is regulated by iron

Science.gov (United States)

Liu, Zhuoming; Lanford, Robert; Mueller, Sebastian; Gerhard, Glenn S.; Luscieti, Sara; Sanchez, Mayka; Devireddy, L.

2013-01-01

Siderophores are best known as small iron binding molecules that facilitate microbial iron transport. In our previous study we identified a siderophore-like molecule in mammalian cells and found that its biogenesis is evolutionarily conserved. A member of the short chain dehydrogenase family of reductases, 3-OH butyrate dehydrogenase (BDH2) catalyzes a rate-limiting step in the biogenesis of the mammalian siderophore. We have shown that depletion of the mammalian siderophore by inhibiting expression of bdh2 results in abnormal accumulation of cellular iron and mitochondrial iron deficiency. These observations suggest that the mammalian siderophore is a critical regulator of cellular iron homeostasis and facilitates mitochondrial iron import. By utilizing bioinformatics, we identified an iron-responsive element (IRE; a stem-loop structure that regulates genes expression post-transcriptionally upon binding to iron regulatory proteins or IRPs) in the 3′-untranslated region (3′-UTR) of the human BDH2 (hBDH2) gene. In cultured cells as well as in patient samples we now demonstrate that the IRE confers iron-dependent regulation on hBDH2 and binds IRPs in RNA electrophoretic mobility shift assays. In addition, we show that the hBDH2 IRE associates with IRPs in cells and that abrogation of IRPs by RNAi eliminates the iron-dependent regulation of hBDH2 mRNA. The key physiologic implication is that iron-mediated post-transcriptional regulation of hBDH2 controls mitochondrial iron homeostasis in human cells. These observations provide a new and an unanticipated mechanism by which iron regulates its intracellular trafficking. PMID:22527885
New insights into iron deficiency and iron deficiency anemia.

Science.gov (United States)

Camaschella, Clara

2017-07-01

Recent advances in iron metabolism have stimulated new interest in iron deficiency (ID) and its anemia (IDA), common conditions worldwide. Absolute ID/IDA, i.e. the decrease of total body iron, is easily diagnosed based on decreased levels of serum ferritin and transferrin saturation. Relative lack of iron in specific organs/tissues, and IDA in the context of inflammatory disorders, are diagnosed based on arbitrary cut offs of ferritin and transferrin saturation and/or marker combination (as the soluble transferrin receptor/ferritin index) in an appropriate clinical context. Most ID patients are candidate to traditional treatment with oral iron salts, while high hepcidin levels block their absorption in inflammatory disorders. New iron preparations and new treatment modalities are available: high-dose intravenous iron compounds are becoming popular and indications to their use are increasing, although long-term side effects remain to be evaluated. Copyright © 2017 Elsevier Ltd. All rights reserved.
Iron absorption studies

International Nuclear Information System (INIS)

Ekenved, G.

1976-01-01

The main objective of the present work was to study iron absorption from different iron preparations in different types of subjects and under varying therapeutic conditions. The studies were performed with different radioiron isotope techniques and with a serum iron technique. The preparations used were solutions of ferrous sulphate and rapidly-disintegrating tablets containing ferrous sulphate, ferrous fumarate and ferrous carbonate and a slow-release ferrous sulphate tablet of an insoluble matrix type (Duroferon Durules). The serum iron method was evaluated and good correlation was found between the serum iron response and the total amount of iron absorbed after an oral dose of iron given in solution or in tablet form. New technique for studying the in-vivo release properties of tablets was presented. Iron tablets labelled with a radio-isotope were given to healthy subjects. The decline of the radioactivity in the tablets was followed by a profile scanning technique applied to different types of iron tablets. The release of iron from the two types of tablets was shown to be slower in vivo than in vitro. It was found that co-administration of antacids and iron tablets led to a marked reduction in the iron absorption and that these drugs should not be administered sumultaneously. A standardized meal markedly decreased the absorbability of iron from iron tablets. The influence of the meal was more marked with rapidly-disintegrating than with slow-release ferrous sulphate tablets. The absorption from rapidly-disintegrating and slow-release ferrous sulphate tablets was compared under practical clinical conditions during an extended treatment period. The studies were performed in healthy subjects, blood donors and patients with iron deficiency anaemia and it was found that the absorption of iron from the slow-release tablets was significantly better than from the rapidly-disintegrating tablets in all three groups of subjects. (author)
Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

Science.gov (United States)

Scholz, Florian; Löscher, Carolin R.; Fiskal, Annika; Sommer, Stefan; Hensen, Christian; Lomnitz, Ulrike; Wuttig, Kathrin; Göttlicher, Jörg; Kossel, Elke; Steininger, Ralph; Canfield, Donald E.

2016-11-01

Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface. Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations >300 nM. At the boundary between sulfidic and nitrogenous conditions, iron concentrations dropped sharply to <20 nM coincident with a maximum in particulate iron concentration. Within the iron gradient, we found an increased expression of the key functional marker gene for nitrate reduction (narG). Part of this upregulation was related to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen fixation, photosynthesis and respiration, nitrate-dependent iron oxidation likely represents a key-link between the marine biogeochemical cycles of nitrogen, oxygen and carbon.
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... and severity. Treatments may include iron supplements, procedures, surgery, and dietary ... iron supplements, also called iron pills or oral iron, by mouth once or several times a ...
Efficacy of iron fortification compared to iron supplementation among Vietnamese schoolchildren.

Science.gov (United States)

Thi Le, Huong; Brouwer, Inge D; Burema, Jan; Nguyen, Khan Cong; Kok, Frans J

2006-12-05

The effect of iron fortification is generally assumed to be less than iron supplementation; however, the magnitude of difference in effects is not known. The present study aims to compare the efficacy of these two strategies on anaemia and iron status. After screening on low Hb, 425 anaemic children in six primary schools in Tam Nong district of Phu Tho province were included in a randomized, placebo-controlled trial comparing two groups receiving iron fortified instant noodles or iron supplementation for 6 months and a control group, with children in all groups having been dewormed. Blood samples were collected before and after intervention for haemoglobin, serum ferritin (SF), serum transferrin receptor (TfR), C-reactive protein (CRP), and haemoglobinopathies analysis. Regression analysis was used to assess the effect of iron fortification and iron supplementation on haemoglobin concentration, SF, TfR, body iron, and anaemic status as outcome variables. The improvement of haemoglobin, SF, and body iron level in the group receiving iron fortification was 42% (2.6 g/L versus 6.2 g/L), 20% (23.5 microg/L versus 117.3 microg/L), and 31.3% (1.4 mg/kg versus 4.4 mg/kg) of that in the iron supplementation group. The prevalence of anaemia dropped to 15.1% in the control group, with an additional reduction of anaemia of 8.5% in the iron supplementation group. The additional reduction due to iron fortification was 5.4%, which amounts to well over 50% of the impact of supplementation. In conclusion, the efficacy of iron fortification based on reduction of prevalence of anaemia, and on the change in haemoglobin level, is about half of the maximum impact of supplementation in case of optimal compliance. Thus, in a population of anaemic children with mild iron deficiency, iron fortification should be the preferred strategy to combat anaemia.
Iron-Deficiency Anemia

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Full Text Available ... iron-rich foods, especially during certain stages of life when more iron is needed, such as childhood and pregnancy. Good sources of iron are meat, poultry, fish, and iron- ...
Measurement of iron absorption from meals contaminated with iron

International Nuclear Information System (INIS)

Hallberg, L.; Bjoern-Rasmussen, E.

1981-01-01

A method is described to measure in vitro the extent of isotopic exchange between the native nonheme food iron and added inorganic reduction to radioiron tracer. The food is digested with pepsin and trypsin in the presence of radioiron. The exchangeability of food iron is calculated from the specific activity in the food and in an extract of bathophenantroline in isoamyl alcohol obtained after digesting this food. The precision and accuracy of the method is illustrated by two kinds of studies, those in which different amounts of contamination iron are added to a meal and those evaluating contamination iron in natural meals. The present method will make it possible to measure validly iron absorption from meals contaminated with unknown amounts of iron of unknown exchangeability with the extrinsic radioiron tracer
Immobilization of Uranium Silicides in Sintered Glass

International Nuclear Information System (INIS)

Mateos, P.; Russo, D.O.; Heredia, A.D.; Sanfilippo, M.

2003-01-01

High activity nuclear spent fuels vitrification by fusion is a well known technology which has industrial scale in France, England, Japan, EEUU. Borosilicates glasses are used in this process.Sintered glasses are an alternative to the immobilization task in which there is also a wide experience around the world.The available technics are: cold pressing and sintering , hot-pressing and hot isostatic pressing.This work compares Borosilicates and Iron silicates sintered glasses behaviour when different ammounts of nuclear simulated waste is added
Iron in diet

Science.gov (United States)

... Reasonable amounts of iron are also found in lamb, pork, and shellfish. Iron from vegetables, fruits, grains, ... strawberries, tomatoes, and potatoes) also increase iron absorption. Cooking foods in a cast-iron skillet can also ...
49 CFR 192.489 - Remedial measures: Cast iron and ductile iron pipelines.

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Remedial measures: Cast iron and ductile iron... for Corrosion Control § 192.489 Remedial measures: Cast iron and ductile iron pipelines. (a) General graphitization. Each segment of cast iron or ductile iron pipe on which general graphitization is found to a...
Iron status in Danish women, 1984-1994: a cohort comparison of changes in iron stores and the prevalence of iron deficiency and iron overload

DEFF Research Database (Denmark)

Milman, N.; Byg, K.E.; Ovesen, Lars

2003-01-01

Background and objectives: From 1954 to 1986, flour in Denmark was fortified with 30 mg carbonyl iron per kilogram. This mandatory enrichment of cereal products was abolished in 1987. The aim was to evaluate iron status in the Danish female population before and after abolishment of iron...... fortification. Methods: Iron status, serum ferritin and haemoglobin, was assessed in population surveys in 1983-1984 comprising 1221 Caucasian women (1089 non-blood-donors, 130 donors) and in 1993-1994 comprising 1261 women (1155 non-blood-donors, 104 donors) equally distributed in age cohorts of 40, 50, 60......, postmenopausal women had median ferritin of 75 mug/L and in 1994 of 93 mug/L (P iron stores (ferritin iron stores (ferritin less...
Iron Dextran Injection

Science.gov (United States)

Iron dextran injection is used to treat iron-deficiency anemia (a lower than normal number of red blood cells ... treated with iron supplements taken by mouth. Iron dextran injection is in a class of medications called ...
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... to moderate iron-deficiency anemia, or red blood cell transfusion for severe iron-deficiency anemia. You may ... body needs iron to make healthy red blood cells. Iron-deficiency anemia usually develops over time because ...
Iron-Deficiency Anemia

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Full Text Available ... you are diagnosed with iron-deficiency anemia. Risk Factors You may have an increased risk for iron- ... iron-deficiency anemia if you have certain risk factors , including pregnancy. To prevent iron-deficiency anemia, your ...
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... from developing iron-deficiency anemia. Foods that are good sources of iron include dried beans, dried fruits, ... iron is needed, such as childhood and pregnancy. Good sources of iron are meat, poultry, fish, and ...
Iron-Deficiency Anemia

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Full Text Available ... enough iron-rich foods, such as meat and fish, may result in you getting less than the ... pregnancy. Good sources of iron are meat, poultry, fish, and iron-fortified foods that have iron added. ...

Iron-Deficiency Anemia

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Full Text Available ... that are good sources of iron include dried beans, dried fruits, eggs, lean red meat, salmon, iron- ... of iron, including iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach and other dark ...
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... developing iron-deficiency anemia. Foods that are good sources of iron include dried beans, dried fruits, eggs, ... is needed, such as childhood and pregnancy. Good sources of iron are meat, poultry, fish, and iron- ...
Iron-Deficiency Anemia

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Full Text Available ... iron in your body is low. For this reason, other iron tests are also done. Ferritin measure ... iron is needed, such as childhood and pregnancy. Good sources of iron are meat, poultry, fish, and ...
Iron-Deficiency Anemia

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Full Text Available ... develop new therapies for conditions that affect the balance of iron in the body and lead to ... Disease Control and Prevention) Iron - Health Professional Fact Sheet (NIH) Iron Dietary Supplement Fact Sheet (NIH) Iron- ...
Mineralogy and geochemistry of banded iron formation and iron ...

Indian Academy of Sciences (India)

The geological complexities of banded iron formation (BIF) and associated iron ores of Jilling–. Langalata iron ore ...... sure to sea water. Uranium in these samples varies ..... Ce oxidation and removal (Elderfield and Greaves. 1982; De Baar et ...
Efficacy of iron fortification compared to iron supplementation among Vietnamese schoolchildren

Directory of Open Access Journals (Sweden)

Nguyen Khan

2006-12-01

Full Text Available Abstract The effect of iron fortification is generally assumed to be less than iron supplementation; however, the magnitude of difference in effects is not known. The present study aims to compare the efficacy of these two strategies on anaemia and iron status. After screening on low Hb, 425 anaemic children in six primary schools in Tam Nong district of Phu Tho province were included in a randomized, placebo-controlled trial comparing two groups receiving iron fortified instant noodles or iron supplementation for 6 months and a control group, with children in all groups having been dewormed. Blood samples were collected before and after intervention for haemoglobin, serum ferritin (SF, serum transferrin receptor (TfR, C-reactive protein (CRP, and haemoglobinopathies analysis. Regression analysis was used to assess the effect of iron fortification and iron supplementation on haemoglobin concentration, SF, TfR, body iron, and anaemic status as outcome variables. The improvement of haemoglobin, SF, and body iron level in the group receiving iron fortification was 42% (2.6 g/L versus 6.2 g/L, 20% (23.5 μg/L versus 117.3 μg/L, and 31.3% (1.4 mg/kg versus 4.4 mg/kg of that in the iron supplementation group. The prevalence of anaemia dropped to 15.1% in the control group, with an additional reduction of anaemia of 8.5% in the iron supplementation group. The additional reduction due to iron fortification was 5.4%, which amounts to well over 50% of the impact of supplementation. In conclusion, the efficacy of iron fortification based on reduction of prevalence of anaemia, and on the change in haemoglobin level, is about half of the maximum impact of supplementation in case of optimal compliance. Thus, in a population of anaemic children with mild iron deficiency, iron fortification should be the preferred strategy to combat anaemia.
Iron-Deficiency Anemia

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Full Text Available ... for your body to absorb iron from the gastrointestinal tract (GI tract). Blood loss When you lose blood, ... iron deficiency. Endurance athletes lose iron through their gastrointestinal tracts. They also lose iron through the breakdown of ...
Iron-Deficiency Anemia

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Full Text Available ... Home / < Back To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español ... bleeding Consuming less than recommended daily amounts of iron Iron-deficiency anemia can be caused by getting ...
Iron homeostasis and its disruption in mouse lung in iron deficiency and overload.

Science.gov (United States)

Giorgi, Gisela; D'Anna, María Cecilia; Roque, Marta Elena

2015-10-01

What is the central question of this study? The aim was to explore the role and hitherto unclear mechanisms of action of iron proteins in protecting the lung against the harmful effects of iron accumulation and the ability of pulmonary cells to mobilize iron in iron deficiency. What is the main finding and its importance? We show that pulmonary hepcidin appears not to modify cellular iron mobilization in the lung. We propose pathways for supplying iron to the lung in iron deficiency and for protecting the lung against iron excess in iron overload, mediated by the co-ordinated action of iron proteins, such as divalent metal transporter 1, ZRT-IRE-like-protein 14, transferrin receptor, ferritin, haemochromatosis-associated protein and ferroportin. Iron dyshomeostasis is associated with several forms of chronic lung disease, but its mechanisms of action remain to be elucidated. The aim of the present study was to determine the role of the lung in whole-animal models with iron deficiency and iron overload, studying the divalent metal transporter 1 (DMT1), ZRT-IRE-like protein 14 (ZIP14), transferrin receptor (TfR), haemochromatosis-associated protein (HFE), hepcidin, ferritin and ferroportin (FPN) expression. In each model, adult CF1 mice were divided into the following groups (six mice per group): (i) iron-overload model, iron saccharate i.p. and control group (iron adequate), 0.9% NaCl i.p.; and (ii) iron-deficiency model, induced by repeated bleeding, and control group (sham operated). Proteins were assessed by immunohistochemistry and Western blot. In control mice, DMT1 was localized in the cytoplasm of airway cells, and in iron deficiency and overload it was in the apical membrane. Divalent metal transporter 1 and TfR increased in iron deficiency, without changes in iron overload. ZRT-IRE-like protein 14 decreased in airway cells in iron deficiency and increased in iron overload. In iron deficiency, HFE and FPN were immunolocalized close to the apical membrane
Iron-Deficiency Anemia

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Full Text Available ... blocks the intestine from taking up iron. Other medical conditions Other medical conditions that may lead to iron-deficiency anemia ... daily amount of iron. If you have other medical conditions that cause iron-deficiency anemia , such as ...
Serum iron test

Science.gov (United States)

Fe+2; Ferric ion; Fe++; Ferrous ion; Iron - serum; Anemia - serum iron; Hemochromatosis - serum iron ... A blood sample is needed. Iron levels are highest in the morning. Your health care provider will likely have you do this test in the morning.
Liver Iron Contents in Rats after Administration of Certain Iron ...

African Journals Online (AJOL)

The effect of consumption of certain iron compounds on liver iron deposition was ... extra iron probably depends on the type of food prepared, .... main groups. Each main group consisted of 4 subgroups. (8 rats per subgroup) which received the same basic diet but differing amounts of iron of a specific type. Each animal was ...
Iron Homeostasis in Mycobacterium tuberculosis: Mechanistic Insights into Siderophore-Mediated Iron Uptake

Science.gov (United States)

2016-01-01

Mycobacterium tuberculosis requires iron for normal growth but faces a limitation of the metal ion due to its low solubility at biological pH and the withholding of iron by the mammalian host. The pathogen expresses the Fe3+-specific siderophores mycobactin and carboxymycobactin to chelate the metal ion from insoluble iron and the host proteins transferrin, lactoferrin, and ferritin. Siderophore-mediated iron uptake is essential for the survival of M. tuberculosis, as knockout mutants, which were defective in siderophore synthesis or uptake, failed to survive in low-iron medium and inside macrophages. But as excess iron is toxic due to its catalytic role in the generation of free radicals, regulation of iron uptake is necessary to maintain optimal levels of intracellular iron. The focus of this review is to present a comprehensive overview of iron homeostasis in M. tuberculosis that is discussed in the context of mycobactin biosynthesis, transport of iron across the mycobacterial cell envelope, and storage of excess iron. The clinical significance of the serum iron status and the expression of the iron-regulated protein HupB in tuberculosis (TB) patients is presented here, highlighting the potential of HupB as a marker, notably in extrapulmonary TB cases. PMID:27402628
IRON CONTENT OF FOOD COOKED IN IRON UTENSILS: A TRADITIONAL INDIAN WAY

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Bibifatima Bawakhan

2016-08-01

Full Text Available BACKGROUND Since most of the Indian population depends on vegetarian diet, prevalence of iron deficiency status is higher in India compared to other developing countries. In spite of many national programs and treatment options available in correcting this, the incidence is increasing due to poor patient compliance and intolerance to treatment. This study was an effort to show how iron content of Indian food can be increased just by following the traditional way of cooking. OBJECTIVE To compare the iron levels in the Jowar roti cooked in iron and non-iron utensils. METHODOLOGY A cross-sectional study was conducted at KIMS, Hubli. Jowar rotis were prepared from equal quantity of jowar flour in iron and non-iron tawa. Another sample of roti was prepared in iron tawa after treating with lemon juice. Six samples were homogenised and filtered. The filtrates were replicated and analysed for iron levels by FerroZine method. RESULTS In the present study, we found no change in iron levels in the roti prepared in non-iron utensil, 1.45 and 1.94 fold increase in the roti prepared in new iron tawa without water boiled in it and with water boiled in it for dough preparation respectively when compared with iron levels of plain jowar flour. There was 5.77 fold rise in iron levels in lemon juice treated roti which signifies the bioavailability of iron in food. The study showed statistical significance at ‘p’- value < 0.05. CONCLUSION Several studies have shown the similar results and this was done to strengthen the findings in our staple food. Hence, the daily iron requirement can be met easily and effectively by taking the food cooked with lemon juice in iron utensils.
Nutritional iron deficiency

NARCIS (Netherlands)

Zimmermann, M.B.; Hurrell, R.F.

2007-01-01

Iron deficiency is one of the leading risk factors for disability and death worldwide, affecting an estimated 2 billion people. Nutritional iron deficiency arises when physiological requirements cannot be met by iron absorption from diet. Dietary iron bioavailability is low in populations consuming
Compacted graphite iron: Cast iron makes a comeback

Science.gov (United States)

Dawson, S.

1994-08-01

Although compacted graphite iron has been known for more than four decades, the absence of a reliable mass-production technique has resulted in relatively little effort to exploit its operational benefits. However, a proven on-line process control technology developed by SinterCast allows for series production of complex components in high-quality CGI. The improved mechanical properties of compacted graphite iron relative to conventional gray iron allow for substantial weight reduction in gasoline and diesel engines or substantial increases in horsepower, or an optimal combination of both. Concurrent with these primary benefits, CGI also provides significant emissions and fuel efficiency benefits allowing automakers to meet legislated performance standards. The operational and environmental benefits of compacted graphite iron together with its low cost and recyclability reinforce cast iron as a prime engineering material for the future.
Colour Metallography of Cast Iron - Chapter 2: Grey Iron (Ⅱ

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Zhou Jiyang

2009-08-01

Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour
Iron-Deficiency Anemia

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Full Text Available ... peas, tofu, dried fruits, and dark green leafy vegetables. Foods rich in vitamin C, such as oranges, strawberries, ... iron are meat, poultry, fish, and iron-fortified foods that have iron ... green leafy vegetables. You can also take an iron supplement. Follow ...
Iron deficiency anemia

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Anemia - iron deficiency ... iron from old red blood cells. Iron deficiency anemia develops when your body's iron stores run low. ... You may have no symptoms if the anemia is mild. Most of the time, ... slowly. Symptoms may include: Feeling weak or tired more often ...
Iron metabolism and toxicity

International Nuclear Information System (INIS)

Papanikolaou, G.; Pantopoulos, K.

2005-01-01

Iron is an essential nutrient with limited bioavailability. When present in excess, iron poses a threat to cells and tissues, and therefore iron homeostasis has to be tightly controlled. Iron's toxicity is largely based on its ability to catalyze the generation of radicals, which attack and damage cellular macromolecules and promote cell death and tissue injury. This is lucidly illustrated in diseases of iron overload, such as hereditary hemochromatosis or transfusional siderosis, where excessive iron accumulation results in tissue damage and organ failure. Pathological iron accumulation in the liver has also been linked to the development of hepatocellular cancer. Here we provide a background on the biology and toxicity of iron and the basic concepts of iron homeostasis at the cellular and systemic level. In addition, we provide an overview of the various disorders of iron overload, which are directly linked to iron's toxicity. Finally, we discuss the potential role of iron in malignant transformation and cancer

Oral sucrosomial iron versus intravenous iron in anemic cancer patients without iron deficiency receiving darbepoetin alfa: a pilot study.

Science.gov (United States)

Mafodda, Antonino; Giuffrida, D; Prestifilippo, A; Azzarello, D; Giannicola, R; Mare, M; Maisano, R

2017-09-01

Erythropoiesis-stimulating agents (ESAs) are often used in treatment of patients with chemotherapy-induced anemia. Many studies have demonstrated an improved hemoglobin (Hb) response when ESA is combined with intravenous iron supplementation and a higher effectiveness of intravenous iron over traditional oral iron formulations. A new formulation of oral sucrosomial iron featuring an increased bioavailability compared to traditional oral formulations has recently become available and could provide a valid alternative to those by intravenous (IV) route. Our study evaluated the performance of sucrosomial iron versus intravenous iron in increasing hemoglobin in anemic cancer patients receiving chemotherapy and darbepoetin alfa, as well as safety, need of transfusion, and quality of life (QoL). The present study considered a cohort of 64 patients with chemotherapy-related anemia (Hb >8 g/dL iron deficiency, scheduled to receive chemotherapy and darbepoetin. All patients received darbepoetin alfa 500 mcg once every 3 weeks and were randomly assigned to receive 8 weeks of IV ferric gluconate 125 mg weekly or oral sucrosomial iron 30 mg daily. The primary endpoint was to demonstrate the performance of oral sucrosomial iron in improving Hb response, compared to intravenous iron. The Hb response was defined as the Hb increase ≥2 g/dL from baseline or the attainment Hb ≥ 12 g/dL. There was no difference in the Hb response rate between the two treatment arms. Seventy one percent of patients treated with IV iron achieved an erythropoietic response, compared to 70% of patients treated with oral iron. By conventional criteria, this difference is considered to be not statistically significant. There were also no differences in the proportion of patients requiring red blood cell transfusions and changes in QoL. Sucrosomial oral iron was better tolerated. In cancer patients with chemotherapy-related anemia receiving darbepoetin alfa, sucrosomial oral iron provides
Preparation and chemical stability of iron-nitride-coated iron microparticles

International Nuclear Information System (INIS)

Luo Xin; Liu Shixiong

2007-01-01

Iron-nitride-coated iron microparticles were prepared by nitridation of the surface of iron microparticles with ammonia gas at a temperature of 510 deg. C. The phases, composition, morphology, magnetic properties, and chemical stability of the particles were studied. The phases were α-Fe, ε-Fe 3 N, and γ-Fe 4 N. The composition varied from the core to the surface, with 99.8 wt% Fe in the core, and 93.8 wt% Fe and 6 wt% N in the iron-nitride coating. The thickness of the iron-nitride coating was about 0.28 μm. The chemical stability of the microparticles was greatly improved, especially the corrosion resistance in corrosive aqueous media. The saturation magnetization and the coercive force were 17.1x10 3 and 68 kA/m, respectively. It can be concluded that iron-nitride-coated iron microparticles will be very useful in many fields, such as water-based magnetorheological fluids and polishing fluids
Obesity alters adipose tissue macrophage iron content and tissue iron distribution.

Science.gov (United States)

Orr, Jeb S; Kennedy, Arion; Anderson-Baucum, Emily K; Webb, Corey D; Fordahl, Steve C; Erikson, Keith M; Zhang, Yaofang; Etzerodt, Anders; Moestrup, Søren K; Hasty, Alyssa H

2014-02-01

Adipose tissue (AT) expansion is accompanied by the infiltration and accumulation of AT macrophages (ATMs), as well as a shift in ATM polarization. Several studies have implicated recruited M1 ATMs in the metabolic consequences of obesity; however, little is known regarding the role of alternatively activated resident M2 ATMs in AT homeostasis or how their function is altered in obesity. Herein, we report the discovery of a population of alternatively activated ATMs with elevated cellular iron content and an iron-recycling gene expression profile. These iron-rich ATMs are referred to as MFe(hi), and the remaining ATMs are referred to as MFe(lo). In lean mice, ~25% of the ATMs are MFe(hi); this percentage decreases in obesity owing to the recruitment of MFe(lo) macrophages. Similar to MFe(lo) cells, MFe(hi) ATMs undergo an inflammatory shift in obesity. In vivo, obesity reduces the iron content of MFe(hi) ATMs and the gene expression of iron importers as well as the iron exporter, ferroportin, suggesting an impaired ability to handle iron. In vitro, exposure of primary peritoneal macrophages to saturated fatty acids also alters iron metabolism gene expression. Finally, the impaired MFe(hi) iron handling coincides with adipocyte iron overload in obese mice. In conclusion, in obesity, iron distribution is altered both at the cellular and tissue levels, with AT playing a predominant role in this change. An increased availability of fatty acids during obesity may contribute to the observed changes in MFe(hi) ATM phenotype and their reduced capacity to handle iron.
Iron-biofortified rice improves the iron stores of nonanemic Filipino women.

Science.gov (United States)

Haas, Jere D; Beard, John L; Murray-Kolb, Laura E; del Mundo, Angelita M; Felix, Angelina; Gregorio, Glenn B

2005-12-01

Iron deficiency is endemic in much of the world, and food system-based approaches to eradication may be viable with new plant breeding approaches to increase the micronutrient content in staple crops. It is thought that conventional plant breeding approaches provide varieties of rice that have 400-500% higher iron contents than varieties commonly consumed in much of Asia. The efficacy of consuming high-iron rice was tested during a 9-mo feeding trial with a double-blind dietary intervention in 192 religious sisters living in 10 convents around metro Manila, the Philippines. Subjects were randomly assigned to consume either high-iron rice (3.21 mg/kg Fe) or a local variety of control rice (0.57 mg/kg Fe), and daily food consumption was monitored. The high-iron rice contributed 1.79 mg Fe/d to the diet in contrast to 0.37 mg Fe/d from the control rice. The 17% difference in total dietary iron consumption compared with controls (10.16 +/- 1.06 vs. 8.44 +/- 1.82 mg/d) resulted in a modest increase in serum ferritin (P = 0.10) and total body iron (P = 0.06) and no increase in hemoglobin (P = 0.59). However, the response was greater in nonanemic subjects for ferritin (P = 0.02) and body iron (P = 0.05), representing a 20% increase after controlling for baseline values and daily rice consumption. The greatest improvements in iron status were seen in those nonanemic women who had the lowest baseline iron status and in those who consumed the most iron from rice. Consumption of biofortified rice, without any other changes in diet, is efficacious in improving iron stores of women with iron-poor diets in the developing world.
Iron Supplementation, Response in Iron-Deficiency Anemia: Analysis of Five Trials.

Science.gov (United States)

Okam, Maureen M; Koch, Todd A; Tran, Minh-Ha

2017-08-01

Oral iron-replacement therapy is the mainstay of treatment for iron-deficiency anemia, but it is often poorly tolerated or ineffective. Hemoglobin response at day 14 of oral iron may be useful in assessing whether and when to transition patients from oral to intravenous (IV) iron. Pooled data from 5 randomized trials were analyzed to compare oral and IV iron-replacement therapy for iron-deficiency anemia. Treatment criteria and assignment to oral versus IV iron were defined per protocol; this analysis included only subjects receiving oral iron. Responders were subjects with ≥1.0-g/dL increases in hemoglobin at day 14, and nonresponders were those with smaller increases. Demographic and clinical characteristics were evaluated for association with hemoglobin response at multiple timepoints. Most subjects (72.8%) were classified as responders. The proportion of subjects with hemoglobin increases ≥1.0, ≥2.0, and ≥3.0 g/dL was greatest among those with postpartum anemia, intermediate among those with heavy uterine bleeding or gastrointestinal-related causes of anemia, and lowest among those with other causes; this proportion was also significantly greater among responders than nonresponders. A ≥1.0-g/dL increase in hemoglobin on day 14 most accurately predicted satisfactory overall hemoglobin response to oral iron on day 42/56 (sensitivity 90.1%; specificity 79.3%; positive and negative predictive values of 92.9% and 72.7%, respectively). Iron-replacement therapy improved quality of life and reduced fatigue. Hemoglobin responses <1.0 g/dL at day 14 of oral iron identify subjects with iron-deficiency anemia who should be transitioned to IV iron supplementation. Copyright © 2017 Elsevier Inc. All rights reserved.
Iron homeostasis during pregnancy.

Science.gov (United States)

Fisher, Allison L; Nemeth, Elizabeta

2017-12-01

During pregnancy, iron needs to increase substantially to support fetoplacental development and maternal adaptation to pregnancy. To meet these iron requirements, both dietary iron absorption and the mobilization of iron from stores increase, a mechanism that is in large part dependent on the iron-regulatory hormone hepcidin. In healthy human pregnancies, maternal hepcidin concentrations are suppressed in the second and third trimesters, thereby facilitating an increased supply of iron into the circulation. The mechanism of maternal hepcidin suppression in pregnancy is unknown, but hepcidin regulation by the known stimuli (i.e., iron, erythropoietic activity, and inflammation) appears to be preserved during pregnancy. Inappropriately increased maternal hepcidin during pregnancy can compromise the iron availability for placental transfer and impair the efficacy of iron supplementation. The role of fetal hepcidin in the regulation of placental iron transfer still remains to be characterized. This review summarizes the current understanding and addresses the gaps in knowledge about gestational changes in hematologic and iron variables and regulatory aspects of maternal, fetal, and placental iron homeostasis. © 2017 American Society for Nutrition.
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... also are hoping to determine which iron supplements work best to treat iron-deficiency anemia in children who do not consume the daily recommended amount of iron. Read less Participate in NHLBI Clinical Trials We lead or sponsor many studies related to iron-deficiency anemia. See if you ...
Comparison of response between food supplemented with powdered iron and iron in syrup form for iron deficiency anemia

International Nuclear Information System (INIS)

Ahmed, P.

2003-01-01

Objective: To evaluate and compare the response between food supplemented with iron in powdered and iron in syrup forms for the treatment of iron deficiency anemia in children aged 1-5 years. Results: Over half (51 %) of the patients were between 1-2 years of age. One hundred thirty-two were males and 68 females. Most of the patients belonged to poor socioeconomic class. The iron in powder form was better tolerated than iron syrup as this group witnessed fewer episodes of gastrointestinal disturbances. The rise in mean Hb level after 6 weeks of treatment in group A and B was 1.6 g/dl and 1.9 g/dl respectively. Hemoglobin rise in group B was more than group A but this was statistically non-significant (p>0.05). There was small but significant (p<0.05) rise in serum ferritin in both the groups. There was no significant difference between the two groups for response to the two forms of iron administration. Conclusion: The powdered form of iron is a cost-effective and better tolerated method of iron administration in children and can be considered as an alternate option for the treatment of iron deficiency anemia in children. (author)
Potentiometric determination of hexavalent uranium in uranium silicide samples

International Nuclear Information System (INIS)

Arlegui, Oscar

1999-01-01

The Chilean Nuclear Energy Commission's Department of Nuclear Materials has among its projects the production of fuels elements for nuclear reactors, and, therefore, the Chemical Analysis Laboratory must have a rapid and reliable method for uranium analysis, to control the uranium concentration during each stage of the production process. For this reason the Chilean Nuclear Energy Commission's Chemical Analysis Laboratory has validated a potentiometric method, which is a modification of the Davies and Gray method proposed by A.R. Eberle. This method uses the Potentiometric Titration Technique and is based on the direct and rapid reduction of uranium (VI) to Uranium (IV), in a concentrated phosphoric acid medium, with excess iron (II) used as a reducing agent. In this medium the excess iron (II) selectively oxidizes to iron (III) with nitric acid, using molybdenum (IV) as a catalyzer, the nitrous acid that is produced is eliminated by adding amidosulfuric acid. The solution is diluted with 1M sulfuric acid and the uranium (IV) obtained is titrated potentiometrically with potassium dichromate in the presence of vanadilic sulfate to obtain a better defined final titration point. The samples were softened with hydrochloric acid and nitric acid and later 50 ml were estimated in a 20% sulfuric acid medium. The analytical method was validated by comparing it with Certified Reference Material (C.R.M.) from the New Brunswick Laboratory (NBL), Metallic Uranium, CRM 112-A. The F Test and the T Test show that the value calculated is less than the tabulated value so the result is traceable to the reference material. The quantification limit, sensitivity, precision and accuracy were quantified for the method
Dietary Factors Modulate Iron Uptake in Caco-2 Cells from an Iron Ingot Used as a Home Fortificant to Prevent Iron Deficiency

Directory of Open Access Journals (Sweden)

Ildefonso Rodriguez-Ramiro

2017-09-01

Full Text Available Iron deficiency is a major public health concern and nutritional approaches are required to reduce its prevalence. The aim of this study was to examine the iron bioavailability of a novel home fortificant, the “Lucky Iron Fish™” (LIF (www.luckyironfish.com/shop, Guelph, Canada and the impact of dietary factors and a food matrix on iron uptake from LIF in Caco-2 cells. LIF released a substantial quantity of iron (about 1.2 mM at pH 2 but this iron was only slightly soluble at pH 7 and not taken up by cells. The addition of ascorbic acid (AA maintained the solubility of iron released from LIF (LIF-iron at pH 7 and facilitated iron uptake by the cells in a concentration-dependent manner. In vitro digestion of LIF-iron in the presence of peas increased iron uptake 10-fold. However, the addition of tannic acid to the digestion reduced the cellular iron uptake 7.5-fold. Additionally, LIF-iron induced an overproduction of reactive oxygen species (ROS, similar to ferrous sulfate, but this effect was counteracted by the addition of AA. Overall, our data illustrate the major influence of dietary factors on iron solubility and bioavailability from LIF, and demonstrate that the addition of AA enhances iron uptake and reduces ROS in the intestinal lumen.
In vitro evaluation of iron solubility and dialyzability of various iron fortificants and of iron-fortified milk products targeted for infants and toddlers.

Science.gov (United States)

Kapsokefalou, Maria; Alexandropoulou, Isidora; Komaitis, Michail; Politis, Ioannis

2005-06-01

The objectives of the present study were: to compare the solubility and dialyzability of various iron fortificants (iron pyrophosphate, ferrous bis-glycinate, ferrous gluconate, ferrous lactate, ferrous sulfate) added, in the presence of ascorbic acid, to pasteurized milk samples produced under laboratory conditions; and to compare the solubility and dialyzability of iron in commercial pasteurized, UHT and condensed milk products available in the Greek market fortified with various vitamins and minerals including iron and targeted towards infants (6-12 months old) and toddlers. Iron solubility and dialyzability were determined using a simulated gastrointestinal digestive system. Ferrous dialyzable iron (molecular weight lower than 8000) was used as an index for prediction of iron bioavailability. Ferrous dialyzable iron in pasteurized milk samples fortified with iron pyrophosphate, ferrous lactate and ferrous bis-glycinate was higher (P iron in products fortified with ferrous lactate was not different (P > 0.05) from those fortified with ferrous sulfate. Ferrous dialyzable iron in four condensed commercial milk products was higher (P iron was higher (P iron source, milk processing and the overall product composition affect formation of ferrous dialyzable iron and may determine the success and effectiveness of iron fortification of milk.
Intravenous Iron Therapy in Patients with Iron Deficiency Anemia: Dosing Considerations

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Todd A. Koch

2015-01-01

Full Text Available Objective. To provide clinicians with evidence-based guidance for iron therapy dosing in patients with iron deficiency anemia (IDA, we conducted a study examining the benefits of a higher cumulative dose of intravenous (IV iron than what is typically administered. Methods. We first individually analyzed 5 clinical studies, averaging the total iron deficit across all patients utilizing a modified Ganzoni formula; we then similarly analyzed 2 larger clinical studies. For the second of the larger studies (Study 7, we also compared the efficacy and retreatment requirements of a cumulative dose of 1500 mg ferric carboxymaltose (FCM to 1000 mg iron sucrose (IS. Results. The average iron deficit was calculated to be 1531 mg for patients in Studies 1–5 and 1392 mg for patients in Studies 6-7. The percentage of patients who were retreated with IV iron between Days 56 and 90 was significantly (p<0.001 lower (5.6% in the 1500 mg group, compared to the 1000 mg group (11.1%. Conclusions. Our data suggests that a total cumulative dose of 1000 mg of IV iron may be insufficient for iron repletion in a majority of patients with IDA and a dose of 1500 mg is closer to the actual iron deficit in these patients.
Structural and functional intermetallics - an overview

International Nuclear Information System (INIS)

Varin, R.A.

2000-01-01

This overview presents the current status of the research and development of both structural and functional intermetallics. On the one hand, the discussion is focused on commercialization and existing industrial applications of intermetallics. Within this frame the applications of titanium aluminides (TiAl) for turbocharger rotors and exhaust valves in automotive industry are being discussed. Advances in the applications of TiAl alloys for the next generation of turbine blades in aerospace/aircraft segment are also presented. The entire spectrum of nickel and iron aluminide alloys developed commercially by the Oak Ridge national Laboratory (USA) and the examples of their application in various segments of industry are thoroughly discussed. Some inroads made in the application of directionally solidified (DS) multiphase niobium silicides (Nb 3 Si+Nb 5 Si 3 ) in situ intermetallic composites with the goal of pushing the service temperature envelope of turbine blades to ∼ 1200-1300 o C are also discussed. On the other hand, various topics in basic or curiosity driven research of titanium aluminides and trialuminides, iron aluminides and high temperature structural silicides are discussed. Some very recent findings on the improvements in fracture toughness and strength of titanium trialuminides and magnetic behaviour of unconventionally cold - worked iron aluminides are highlighted. The topic of functional intermetallics is limited to the systems must suitable for hydrogen storage applications. A perspective on the directions of future research and development of intermetallics is also provided. (author)
Anti frictional materials iron-pig iron-brass manufacture using shaving waste products of pig-iron

International Nuclear Information System (INIS)

Nasamov, S. N.; Krivij, N.; Gudenau, H. W.; Babich, A. I.; Garcia, L. L.; Formoso, A.; Cores, A.

2003-01-01

Parts based on iron and steel powders are widely used in the manufacture of automobile and domestic equipment. This work was done to study the anti-friction properties of iron-pig iron-brass compositions of materials which were obtained by pressing and sintering from a mix of iron powders and industrial by products of cast-iron turnings, brass, talc and technical sulphur. Experiments were performed using cold pressure technology in the flowing matrix of the powder composite without solid lubricants. The subsequent sintering was carried out at 1200 degree centigree under isothermal conditions in a nitrogen atmosphere in the sintering zone during 1 h. The physical-mechanical and anti-friction properties were almost double by the active drainage of the gases from the compression mould. The study of the microstructure of the sintered materials showed that free cementite existed between the particle limits and around the pores. large agglomerations of dark inclusions could be observed, consisting of graphite, zinc and iron oxides, which were points of tension in the materials that reduce its durability and, therefore, its wear resistance to dry friction. (Author) 34 refs
Assessment of polyphase sintered iron-cobalt-iron boride cermets

International Nuclear Information System (INIS)

Nowacki, J.; Pieczonka, T.

2004-01-01

Sintering of iron, cobalt and boron powders has been analysed. As a result iron-iron boride, Fe-Fe 2 B and iron/cobalt boride with a slight admixture of molybdenum, Fe - Co - (FeMoCo) 2 B cermets have been produced. Iron was introduced to the mixture as the Astalloy Mo Hoeganaes grade powder. Elemental amorphous boron powder was used, and formation of borides occurred both during heating and isothermal sintering periods causing dimensional changes of the sintered body. Dilatometry was chosen to control basic phenomena taking place during multiphase sintering of investigated systems. The microstructure and phase constituents of sintered compacts were controlled as well. The cermets produced were substituted to: metallographic tests, X-ray analysis, measurements of hardness and of microhardness, and of wear in the process of sliding dry friction. Cermets are made up of two phases; hard grains of iron - cobalt boride, (FeCo) 2 B (1800 HV) constituting the reinforcement and a relatively soft and plastic eutectic mixture Fe 2 B - Co (400-500 HV) constituting the matrix. (author)
Core-shell iron-iron oxide nanoparticles

DEFF Research Database (Denmark)

Kuhn, Luise Theil; Bojesen, A.; Timmermann, L.

2004-01-01

We present studies of the magnetic properties of core-shell iron-iron oxide nanoparticles. By combining Mossbauer and X-ray absorption spectroscopy we have been able to measure the change from a Fe3O4-like to a gamma-Fe2O3-like composition from the interface to the surface. Furthermore, we have...
Assessment of iron deficiency in pregnant women by determining iron status

International Nuclear Information System (INIS)

Raza, N.; Munazza, B.; Ayub, M.; Sarwar, I

2011-01-01

Background: Pregnant women constitute a high risk group for iron deficiency. Maternal iron deficiency and particularly iron deficiency anaemia may be associated with detrimental effects on maternal and infant function and particularly with a higher risk of preterm delivery and delivery of low birth weight neonates. Objective of this study was to assess and compare the iron status of normal healthy non-pregnant women with that of pregnant women of Hazara Division. Methods: This study was conducted at Faculty of Health Sciences, Hazara University, and Ayub Medical College, Abbottabad from first March to /31 August 2006. Altogether 120 women, 90 pregnant at various stages of pregnancy and 30 non-pregnant women as control group were included in this study by convenience sampling. Their iron status was assessed by determination of haemoglobin (Hb), Serum ferritin, Serum-iron, Total Iron Binding Capacity (TIBC), Unsaturated Iron Binding Capacity (UIBC), and Percentage saturation of transferrin. Data generated on these variables were subjected to ANOVA and correlation analysis. Results: The salient finding of this study is a significant decrease in Hb, Serum ferritin, Serum iron, percentage saturation of transferrin and a significant increase in values of TIBC and a pronounced increase in UIBC in second and third trimester compared to first trimester in iron deficient pregnant women. The mean values of Hb, SF, and Fe/TIBC% were significantly lower in the cases than in the control and significantly higher values of TIBC and UIBC were observed in the cases compared to controls. Significant correlations were observed for TIBC, UIBC and Fe/TIBC% against serum iron in different trimesters of pregnancy. Conclusion: A high percentage of the pregnant women are iron deficient due to factors such as high parity, poor dietary habits and socioeconomic status. (author)
Iron

DEFF Research Database (Denmark)

Hansen, Jakob Bondo; Moen, I W; Mandrup-Poulsen, T

2014-01-01

and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation by activation...... of transcription factors, activation of the mitochondrial apoptotic machinery or of other cell death mechanisms. The pro-inflammatory cytokine IL-1β facilitates divalent metal transporter 1 (DMT1)-induced β-cell iron uptake and consequently ROS formation and apoptosis, and we propose that this mechanism provides...
Composites having an intermetallic containing matrix

International Nuclear Information System (INIS)

Nagle, D.C.; Brupbacher, J.M.; Christodoulou, L.

1990-01-01

This paper describes a composite material. It comprises: a dispersion of in-situ precipitated second phase particles selected from the group consisting of borides, carbides, nitrides, and sulfides, in an intermetallic containing matrix selected from the group consisting of the aluminides, silicides, and beryllides of nickel, copper, titanium, cobalt, iron, platinum, gold, silver, niobium, tantalum, zinc, molybdenum, hafnium, tin, tungsten, lithium, magnesium, thorium, chromium, vanadium, zirconium, and manganese
Current understanding of iron homeostasis.

Science.gov (United States)

Anderson, Gregory J; Frazer, David M

2017-12-01

Iron is an essential trace element, but it is also toxic in excess, and thus mammals have developed elegant mechanisms for keeping both cellular and whole-body iron concentrations within the optimal physiologic range. In the diet, iron is either sequestered within heme or in various nonheme forms. Although the absorption of heme iron is poorly understood, nonheme iron is transported across the apical membrane of the intestinal enterocyte by divalent metal-ion transporter 1 (DMT1) and is exported into the circulation via ferroportin 1 (FPN1). Newly absorbed iron binds to plasma transferrin and is distributed around the body to sites of utilization with the erythroid marrow having particularly high iron requirements. Iron-loaded transferrin binds to transferrin receptor 1 on the surface of most body cells, and after endocytosis of the complex, iron enters the cytoplasm via DMT1 in the endosomal membrane. This iron can be used for metabolic functions, stored within cytosolic ferritin, or exported from the cell via FPN1. Cellular iron concentrations are modulated by the iron regulatory proteins (IRPs) IRP1 and IRP2. At the whole-body level, dietary iron absorption and iron export from the tissues into the plasma are regulated by the liver-derived peptide hepcidin. When tissue iron demands are high, hepcidin concentrations are low and vice versa. Too little or too much iron can have important clinical consequences. Most iron deficiency reflects an inadequate supply of iron in the diet, whereas iron excess is usually associated with hereditary disorders. These disorders include various forms of hemochromatosis, which are characterized by inadequate hepcidin production and, thus, increased dietary iron intake, and iron-loading anemias whereby both increased iron absorption and transfusion therapy contribute to the iron overload. Despite major recent advances, much remains to be learned about iron physiology and pathophysiology. © 2017 American Society for Nutrition.

Iron and iron-related proteins in asbestosis.

Science.gov (United States)

ABSTRACT: We tested the postulate that iron homeostasis is altered among patients diagnosed to have asbestosis. Lung tissue from six individuals diagnosed to have had asbestosis at autopsy was stained for iron, ferritin, divalent metal transporter 1 (DMT1), and ferroportin 1 (FP...
Electronic structure and bonding in the ternary silicide YNiSi3

International Nuclear Information System (INIS)

Sung, Gi Hong; Kang, Dae Bok

2003-01-01

An analysis of the electronic structure and bonding in the ternary silicide YNiSi 3 is made, using extended Hueckel tight-binding calculations. The YNiSi 3 structure consists of Ni-capped Si 2 dimer layers and Si zigzag chains. Significant bonding interactions are present between the silicon atoms in the structure. The oxidation state formalism of (Y 3+ )(Ni 0 )(Si 3 ) 3- for YNiSi 3 constitutes a good starting point to describe its electronic structure. Si atoms receive electrons form the most electropositive Y in YNiSi 3 , and Ni 3d and Si 3p states dominate below the Fermi level. There is an interesting electron balance between the two Si and Ni sublattices. Since the π orbitals in the Si chain and the Ni d and s block levels are almost completely occupied, the charge balance for YNiSi 3 can be rewritten as (Y 3+ )(Ni 2- )(Si 2- )(Si-Si) + , making the Si 2 layers oxidized. These results suggest that the Si zigzag chain contains single bonds and the Si 2 double layer possesses single bonds within a dimer with a partial double bond character. Stronger Si-Si and Ni-Si bonding interactions are important for giving stability to the structure, while essentially no metal-metal bonding exists at all. The 2D metallic behavior of this compound is due to the Si-Si interaction leading to dispersion of the several Si 2 π bands crossing the Fermi level in the plane perpendicular to the crystallographic b axis
Rate Theory Modeling and Simulation of Silicide Fuel at LWR Conditions

Energy Technology Data Exchange (ETDEWEB)

Miao, Yinbin [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Ye, Bei [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Hofman, Gerard [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Yacout, Abdellatif [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Gamble, Kyle [Idaho National Lab. (INL), Idaho Falls, ID (United States). Fuel Modeling and Simulation; Mei, Zhi-Gang [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division

2016-08-29

As a promising candidate for the accident tolerant fuel (ATF) used in light water reactors (LWRs), the fuel performance of uranium silicide (U₃Si₂) at LWR conditions needs to be well understood. In this report, rate theory model was developed based on existing experimental data and density functional theory (DFT) calculations so as to predict the fission gas behavior in U₃Si₂ at LWR conditions. The fission gas behavior of U₃Si₂ can be divided into three temperature regimes. During steady-state operation, the majority of the fission gas stays in intragranular bubbles, whereas the dominance of intergranular bubbles and fission gas release only occurs beyond 1000 K. The steady-state rate theory model was also used as reference to establish a gaseous swelling correlation of U₃Si₂ for the BISON code. Meanwhile, the overpressurized bubble model was also developed so that the fission gas behavior at LOCA can be simulated. LOCA simulation showed that intragranular bubbles are still dominant after a 70 second LOCA, resulting in a controllable gaseous swelling. The fission gas behavior of U₃Si₂ at LWR conditions is benign according to the rate theory prediction at both steady-state and LOCA conditions, which provides important references to the qualification of U₃Si₂ as a LWR fuel material with excellent fuel performance and enhanced accident tolerance.
Glutathione, Glutaredoxins, and Iron.

Science.gov (United States)

Berndt, Carsten; Lillig, Christopher Horst

2017-11-20

Glutathione (GSH) is the most abundant cellular low-molecular-weight thiol in the majority of organisms in all kingdoms of life. Therefore, functions of GSH and disturbed regulation of its concentration are associated with numerous physiological and pathological situations. Recent Advances: The function of GSH as redox buffer or antioxidant is increasingly being questioned. New functions, especially functions connected to the cellular iron homeostasis, were elucidated. Via the formation of iron complexes, GSH is an important player in all aspects of iron metabolism: sensing and regulation of iron levels, iron trafficking, and biosynthesis of iron cofactors. The variety of GSH coordinated iron complexes and their functions with a special focus on FeS-glutaredoxins are summarized in this review. Interestingly, GSH analogues that function as major low-molecular-weight thiols in organisms lacking GSH resemble the functions in iron homeostasis. Since these iron-related functions are most likely also connected to thiol redox chemistry, it is difficult to distinguish between mechanisms related to either redox or iron metabolisms. The ability of GSH to coordinate iron in different complexes with or without proteins needs further investigation. The discovery of new Fe-GSH complexes and their physiological functions will significantly advance our understanding of cellular iron homeostasis. Antioxid. Redox Signal. 27, 1235-1251.
Second international round robin for the quantification of serum non-transferrin-bound iron and labile plasma iron in patients with iron-overload disorders

NARCIS (Netherlands)

de Swart, Louise; Hendriks, Jan C. M.; van der Vorm, Lisa N.; Cabantchik, Z. Ioav; Evans, Patricia J.; Hod, Eldad A.; Brittenham, Gary M.; Furman, Yael; Wojczyk, Boguslaw; Janssen, Mirian C. H.; Porter, John B.; Mattijssen, Vera E. J. M.; Biemond, Bart J.; MacKenzie, Marius A.; Origa, Raffaella; Galanello, Renzo; Hider, Robert C.; Swinkels, Dorine W.

2016-01-01

Non-transferrin-bound iron and its labile (redox active) plasma iron component are thought to be potentially toxic forms of iron originally identified in the serum of patients with iron overload. We compared ten worldwide leading assays (6 for non-transferrin-bound iron and 4 for labile plasma iron)
Iron prophylaxis during pregnancy -- how much iron is needed? A randomized dose- response study of 20-80 mg ferrous iron daily in pregnant women

DEFF Research Database (Denmark)

Milman, Nils; Bergholt, Thomas; Eriksen, Lisbeth

2005-01-01

To determine the lowest dose of iron preventative of iron deficiency and iron deficiency anemia in pregnancy.......To determine the lowest dose of iron preventative of iron deficiency and iron deficiency anemia in pregnancy....
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... from developing iron-deficiency anemia. Foods that are good sources of iron include dried beans, dried fruits, eggs, lean red meat, ... signs of iron-deficiency anemia include: Brittle nails ...
Cast irons

CERN Document Server

1996-01-01

Cast iron offers the design engineer a low-cost, high-strength material that can be easily melted and poured into a wide variety of useful, and sometimes complex, shapes. This latest handbook from ASM covers the entire spectrum of one of the most widely used and versatile of all engineered materials. The reader will find the basic, but vital, information on metallurgy, solidification characteristics, and properties. Extensive reviews are presented on the low-alloy gray, ductile, compacted graphite, and malleable irons. New and expanded material has been added covering high-alloy white irons used for abrasion resistance and high-alloy graphitic irons for heat and corrosion resistance. Also discussed are melting furnaces and foundry practices such as melting, inoculation, alloying, pouring, gating and rising, and molding. Heat treating practices including stress relieving, annealing, normalizing, hardening and tempering, autempering (of ductile irons), and surface-hardening treatments are covered, too. ASM Spec...
BASIC program to compute uranium density and void volume fraction in laboratory-scale uranium silicide aluminum dispersion plate-type fuel

International Nuclear Information System (INIS)

Ugajin, Mitsuhiro

1991-05-01

BASIC program simple and easy to operate has been developed to compute uranium density and void volume fraction for laboratory-scale uranium silicide aluminum dispersion plate-type fuel, so called miniplate. An example of the result of calculation is given in order to demonstrate how the calculated void fraction correlates with the microstructural distribution of the void in a miniplate prepared in our laboratory. The program is also able to constitute data base on important parameters for miniplates from experimentally-determined values of density, weight of each constituent and dimensions of miniplates. Utility programs pertinent to the development of the BASIC program are also given which run in the popular MS-DOS environment. All the source lists are attached and brief description for each program is made. (author)
Comparison of food habits, iron intake and iron status in adolescents before and after the withdrawal of the general iron fortification in Sweden.

Science.gov (United States)

Sjöberg, A; Hulthén, L

2015-04-01

Sifted flour was fortified with carbonyl iron for 50 years in Sweden. This study evaluates changes in food habits, intake of iron, factors affecting iron absorption and iron status after the discontinuation of the general iron fortification in adolescents with the highest requirements. A total of 2285 15- to 16-year-old students in 1994 (634 girls and 611 boys) and in 2000 (534 girls and 486 boys) in 13 schools in Gothenburg, Sweden, were included in two cross-sectional surveys assessing food habits with diet history interviews and iron deficiency defined with serum ferritin stores ⩽ 15 μg/l and no preceding infection. In girls, iron deficiency increased from 37 to 45%, while in boys, it was stable at 23%. Total iron intake decreased from 15.7 to 9.5 mg/day and 22.5 to 13.9 mg/day in girls and boys, respectively. Cereals were the main iron source. Among girls, the increase of fish and decrease of calcium intake may not counteract the effect of decreased intake of fortification iron. Among boys, more meat, less calcium and more vitamin C may have favoured the bioavailability of iron. The discontinuation of the general iron fortification resulted in a 39% decrease in total iron intake and iron deficiency increased substantially in girls. However, in boys no change in iron deficiency was observed. Whether this was a result of changed bioavailability of dietary iron or simultaneous changes of non-dietary factors remains to be explored.
Iron-Deficiency Anemia

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Full Text Available ... for iron-deficiency anemia. Lifestyle habits Certain lifestyle habits may increase your risk for iron-deficiency anemia, including: Vegetarian or vegan eating patterns. Not eating enough iron-rich foods, such ...
Use of radionuclides in the study of iron metabolism in iron deficient states

International Nuclear Information System (INIS)

Anatkov, A.; Karakostov, K.; Iliev, Z.; Dimitrov, L.

1977-01-01

A study of erythropoiesis in iron deficient anemias by simultaneous labelling with the radionuclides iron 59 and chromium 51 revealed accelerated iron circuit, higher percentage of daily hemolysis, severely reduced or even absent labile reserves, decreased volume of packed red cells with no decrease of blood volume. Adequate iron 59 utilization was observed after administration of large doses of iron (500 mg) in the treatment of iron deficient anemias. (author)
Prediction of reducible soil iron content from iron extraction data

NARCIS (Netherlands)

Bodegom, van P.M.; Reeven, van J.; Denier van der Gon, H.A.C.

2003-01-01

Soils contain various iron compounds that differ in solubility, reducibility and extractability. Moreover, the contribution of the various iron compounds to total iron (Fe) and total Fe concentrations differs highly among soils. As a result, the total reducible Fe content can also differ among
Taking iron supplements

Science.gov (United States)

... medlineplus.gov/ency/article/007478.htm Taking iron supplements To use the sharing features on this page, ... levels. You may also need to take iron supplements as well to rebuild iron stores in your ...
Iron deficiency anaemia: with the conclusion of a need for iron reader

Science.gov (United States)

Lim, Wai Feng; Yap, Boon Kar; Lai, Mei I.; Talik, Noorazrina; Nasser, Ammar Ahmed; Al-Haiqi, Ahmed Mubarak Ahmed; Sankar Krishnan, Prajindra

2017-10-01

In our bloodstream, there are plenty of red blood cells (RBC), which function as an important oxygen carrier in our bodies. Each RBC consists of millions of haemoglobin (Hb), which is made up from globin and iron. If any deficiency/malfunction of any globin, it will lead to anaemia as indicated in low Hb level while iron deficiency anaemia (IDA) is anaemic due to the lacking of iron as indicated in low Hb and ferritin levels. IDA affects almost two billion people globally while anaemia without iron deficiency, such as thalassaemia, affects almost 4.5% in Malaysian population. These anaemic conditions have similar clinical symptoms like fatigue, dizziness, in which disturb their cognitive development and productivity in workplace. In areas without proper medical access, many anaemic individuals were misdiagnosed and treated with iron tablets because they were thought to have iron deficiency anaemia due to low Hb content. But, excess iron is toxic to the body. Misdiagnosis can be avoided by iron status assessment. We hereby review the currently available iron status parameters in laboratory and field study with the conclusion of demonstrating the importance of a need for iron reader, in the effort to reduce the prevalence of IDA globally.
Iron-Deficiency Anemia

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Full Text Available ... making new blood cells. Visit our Aplastic Anemia Health Topic to learn more. ... recommend that you take iron supplements, also called iron pills or oral iron, by mouth once or several times a ...
Iron-Deficiency Anemia

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Full Text Available ... ESAs are usually used with iron therapy or IV iron, or when iron therapy alone is not enough. Look for Living With will discuss what your doctor may recommend, including lifelong lifestyle changes ...
A kinetic Monte Carlo study of coarsening resistance of novel core/shell precipitates

International Nuclear Information System (INIS)

Zhang, Xuan; Gao, Wenpei; Bellon, Pascal; Averback, Robert S.; Zuo, Jian-Min

2014-01-01

A novel approach towards the design of coarsening-resistant nanoprecipitates in structural alloys was investigated by kinetic Monte Carlo (KMC) simulation. The approach is motivated by recent experimental results in Cu–Nb–W alloys showing that room temperature ion irradiation resulted in W nanoprecipitation, leading to exceptional stability of W-rich-core/Nb-rich-shell nanoprecipitates formed following thermal annealing (Zhang et al., 2013 [11]). Here, image simulations of atomically resolved scanning transmission electron microscopy are performed to establish that these W nanoprecipitates are highly ramified. Thermal precipitate coarsening in an A–B–C ternary alloy similar to Cu–Nb–W is then studied by KMC simulations, where the highly immiscible and refractory C solute atoms are initially distributed into fractal nanoprecipitates, or cores, which become coated by a shell of B atoms during elevated temperature annealing. Compared with nanoprecipitates generated by compact C cores, the ramified nanoprecipitates result in exceptionally high trapping efficiency of B solute atoms during thermal coarsening, and the efficiency increases with the cluster size. The KMC results are analyzed and rationalized by noting that, owing to the Gibbs–Thomson effect, when the curvatures of the shell of the precipitates are zero or negative, the microstructure is coarsening-resistant. Such morphology can be realized by facets, or by dynamic balance within positive, negative and zero curvatures
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... breastfeeding. Recommended daily iron intake for children and adults. The table lists the recommended amounts of iron, ... increased need for iron during growth spurts. Older adults, especially those over age 65. Unhealthy environments Children ...
Iron-Deficiency Anemia

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Full Text Available ... red meat, salmon, iron-fortified breads and cereals, peas, tofu, dried fruits, and dark green leafy vegetables. ... stored iron has been used. Ferritin is a protein that helps store iron in your body. Reticulocyte ...

Iron-Deficiency Anemia

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Full Text Available ... heart failure . Increased risk of infections Motor or cognitive development delays in children Pregnancy complications, such as ... iron-deficiency anemia may require intravenous (IV) iron therapy or a blood transfusion . Iron supplements Your doctor ...
Iron-Deficiency Anemia

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Full Text Available ... drinking black tea, which reduces iron absorption. Other treatments If you have chronic kidney disease and iron- ... and lifestyle changes to avoid complications. Follow your treatment plan Do not stop taking your prescribed iron ...
Iron-Deficiency Anemia

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Full Text Available ... diagnoses you with iron-deficiency anemia, your treatment will depend on the cause and severity of the ... of iron. The recommended daily amounts of iron will depend on your age, sex, and whether you ...
Iron-Deficiency Anemia

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Full Text Available ... girls. From birth to 6 months, babies need 0.27 mg of iron. This number goes up ... screen blood donors for low iron stores. Reliable point-of-care testing may help identify iron deficiency ...
Iron-Deficiency Anemia

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Full Text Available ... you do not have enough iron in your body. People with mild or moderate iron-deficiency anemia ... and where to find more information. Causes Your body needs iron to make healthy red blood cells. ...
Iron-Deficiency Anemia

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Full Text Available ... starch. Restless legs syndrome Shortness of breath Weakness Complications Undiagnosed or untreated iron-deficiency anemia may cause ... as complete blood count and iron studies. Prevent complications over your lifetime To prevent complications from iron- ...
Iron-Deficiency Anemia

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Full Text Available ... lean red meat, salmon, iron-fortified breads and cereals, peas, tofu, dried fruits, and dark green leafy ... sources of iron, including iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach and other ...
Iron-Deficiency Anemia

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Full Text Available ... amount of iron, and medical conditions that make it hard for your body to absorb iron from ... hepcidin. Hepcidin prevents iron from leaving cells where it is stored or from being absorbed in the ...
Iron-Deficiency Anemia

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Full Text Available ... iron-fortified foods that have iron added. Vegetarian diets can provide enough iron if you choose nonmeat ... Anemia in Chronic Kidney Disease (National Institute of Diabetes and Digestive and Kidney Diseases) Avoiding Anemia (National ...
Iron-Deficiency Anemia

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Full Text Available ... bleeding. If undiagnosed or untreated, iron-deficiency anemia can cause serious complications, including heart failure and development ... iron is too low. Low intake of iron can happen because of blood loss, consuming less than ...
Iron-Deficiency Anemia

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Full Text Available ... fruits, eggs, lean red meat, salmon, iron-fortified breads and cereals, peas, tofu, dried fruits, and dark ... choose nonmeat sources of iron, including iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach ...
Iron-Deficiency Anemia

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Full Text Available ... and pregnancy. Good sources of iron are meat, poultry, fish, and iron-fortified foods that have iron ... Anemia Restless Legs Syndrome Von Willebrand Disease Other Resources NHLBI resources Your Guide to Anemia [PDF, 1. ...
Whole-body iron-59 retention measurements for estimating the iron status of piglets

International Nuclear Information System (INIS)

Pfau, A.; Rudolphi, K.; Heinrich, H.C.; Gabbe, E.E.

1976-01-01

A large-volume, 4π whole-body liquid scintillation detector was used to determine 59 Fe absorption in 173 one-to-six-weeks-old piglets with normal and depleted iron stores. Values of intestinal absorption from a 10 μmole (corresponds to 0.558 mg) 59 Fe 2+ test dose were compared with levels of haemoglobin, haematocrit, and serum iron as well as with stainable diffuse iron of bone marrow reticuloendothelial cells, and the dose relationship of intestinal iron absorption from 59 Fe-labelled FeSO 4 and methaemoglobin was measured. The investigations indicated that neither blood parameters, cytochemical gradings nor absorption levels from the 59 Fe test dose alone were sufficient to describe quantitatively the various stages of iron deficiency in piglets. A synopsis of all parameters appeared to be necessary for defining normal iron status and prelatent, latent and manifest iron deficiency. Piglets fed on sows' milk only developed manifest iron deficiency within the first three weeks of age. After an access to soil and/or creep feed from the eighth day of age, or intramuscular injections of 200 mg Fe as iron-dextran at three days of age, or injections of 200 or 400 mg Fe combined with access to creep feed, stages of manifest, latent or prelatent iron deficiency could be observed. For an iron-dextran dose of 800 mg Fe injected in amounts of 400 mg Fe at 3 and 10 days of age, a normal iron status was obtained in three-week-old piglets. The iron dose relationship indicated that 20 mg Fe administered orally as FeSO 4 or 40 mg Fe as methaemoglobin-Fe daily should cover the iron requirement of piglets for the first three weeks of life, whereas a three-week total of iron given orally in a single dose would lead to unphysiological or fatal conditions in nursing pigs. (author)
Cellular iron transport.

Science.gov (United States)

Garrick, Michael D; Garrick, Laura M

2009-05-01

Iron has a split personality as an essential nutrient that also has the potential to generate reactive oxygen species. We discuss how different cell types within specific tissues manage this schizophrenia. The emphasis in enterocytes is on regulating the body's supply of iron by regulating transport into the blood stream. In developing red blood cells, adaptations in transport manage the body's highest flux of iron. Hepatocytes buffer the body's stock of iron. Macrophage recycle the iron from effete red cells among other iron management tasks. Pneumocytes provide a barrier to prevent illicit entry that, when at risk of breaching, leads to a need to handle the dangers in a fashion essentially shared with macrophage. We also discuss or introduce cell types including renal cells, neurons, other brain cells, and more where our ignorance, currently still vast, needs to be removed by future research.
Iron-Deficiency Anemia

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Full Text Available ... because your body’s intake of iron is too low. Low intake of iron can happen because of blood ... delivery or giving birth to a baby with low birth weight In people with chronic conditions, iron- ...
Iron-Deficiency Anemia

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Full Text Available ... for iron-deficiency anemia if you have certain risk factors , including pregnancy. To prevent iron-deficiency anemia, your doctor may recommend you eat heart-healthy foods or control other conditions that can cause iron-deficiency anemia. ...
Iron-Deficiency Anemia

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Full Text Available ... blood cells. Iron-deficiency anemia usually develops over time because your body’s intake of iron is too ... clamping of your newborn’s umbilical cord at the time of delivery. This may help prevent iron-deficiency ...
Iron-Deficiency Anemia

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Full Text Available ... severity of the condition. Your doctor may recommend healthy eating changes, iron supplements, intravenous iron therapy for mild ... you: Adopt healthy lifestyle changes such as heart-healthy eating patterns. Increase your daily intake of iron-rich ...
Iron-Deficiency Anemia

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Full Text Available ... different ages and stages of life. Until the teen years, the recommended amount of iron is the ... cow’s milk. Cow’s milk is low in iron. Teens, who have increased need for iron during growth ...
Experimental studies of thermal and chemical interactions between oxide and silicide nuclear fuels with water

Energy Technology Data Exchange (ETDEWEB)

farahani, A.A.; Corradini, M.L. [Univ. of Wisconsi, Madison, WI (United States)

1995-09-01

Given some transient power/cooling mismatch is a nuclear reactor and its inability to establish the necessary core cooling, energetic fuel-coolant interactions (FCI`s commonly called `vapor explosions`) could occur as a result of the core melting and coolant contact. Although a large number of studies have been done on energetic FCI`s, very few experiments have been performed with the actual fuel materials postulated to be produced in severe accidents. Because of the scarcity of well-characterized FCI data for uranium allows in noncommercial reactors (cermet and silicide fuels), we have conducted a series of experiments to provide a data base for the foregoing materials. An existing 1-D shock-tube facility was modified to handle depleted radioactive materials (U{sub 3}O{sub 8}-Al, and U{sub 3}Si{sub 2}-Al). Our objectives have been to determine the effects of the initial fuel composition and temperature and the driving pressure (triggering) on the explosion work output, dynamic pressures, transient temperatures, and the hydrogen production. Experimental results indicate limited energetics, mainly thermal interactions, for these fuel materials as compared to aluminum where more chemical reactions occur between the molten aluminum and water.

Iron-Deficiency Anemia

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Full Text Available ... iron, in milligrams (mg) at different ages and stages of life. Until the teen years, the recommended amount of ... and choosing iron-rich foods, especially during certain stages of life when more iron is needed, such as childhood ...
Iron-Deficiency Anemia

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Full Text Available ... because your body’s intake of iron is too low. Low intake of iron can happen because of blood ... a lot of cow’s milk. Cow’s milk is low in iron. Teens, who have increased need for ...
Iron-Deficiency Anemia

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Full Text Available ... for iron-deficiency anemia. Lifestyle habits Certain lifestyle habits may increase your risk for iron-deficiency anemia, including: Vegetarian or vegan eating patterns. Not eating enough iron-rich foods, such as meat and fish, may result in ...
Iron-Deficiency Anemia

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Full Text Available ... bleeding or other abnormalities, such as growths or cancer of the lining of the colon. For this test, a ... that you take iron supplements, also called iron pills or oral iron, by mouth once or several times a ...
Iron-57 and iridium-193 Moessbauer spectroscopic studies of supported iron-iridium catalysts

International Nuclear Information System (INIS)

Berry, F.J.; Jobson, S.

1988-01-01

57 Fe and 193 Ir Moessbauer spectroscopy shows that silica- and alumina-supported iron-iridium catalysts formed by calcination in air contain mixtures of small particle iron(III) oxide and iridium(IV) oxide. The iridium dioxide in both supported catalysts is reduced in hydrogen to metallic iridium. The α-Fe 2 O 3 in the silica supported materials is predominantly reduced in hydrogen to an iron-iridium alloy whilst in the alumina-supported catalyst the iron is stabilised by treatment in hydrogen as iron(II). Treatment of a hydrogen-reduced silica-supported iron catalyst in hydrogen and carbon monoxide is accompanied by the formation of iron carbides. Carbide formation is not observed when the iron-iridium catalysts are treated in similar atmospheres. The results from the bimetallic catalysts are discussed in terms of the hydrogenation of associatively adsorbed carbon monoxide and the selectivity of supported iron-iridium catalysts to methanol formation. (orig.)
Nicotianamine synthase overexpression positively modulates iron homeostasis-related genes in high iron rice

Directory of Open Access Journals (Sweden)

Meng eWang

2013-05-01

Full Text Available Nearly one-third of the world population, mostly women and children, suffer from iron malnutrition and its consequences, such as anemia or impaired mental development. Biofortification of rice, which is a staple crop for nearly half of the world’s population, can significantly contribute in alleviating iron deficiency. NFP rice (transgenic rice expressing nicotianamine synthase, ferritin and phytase genes has a more than six-fold increase in iron content in polished rice grains, resulting from the synergistic action of nicotianamine synthase (NAS and ferritin transgenes. We investigated iron homeostasis in NFP plants by analyzing the expression of 28 endogenous rice genes known to be involved in the homeostasis of iron and other metals, in iron-deficient and iron-sufficient conditions. RNA was collected from different tissues (roots, flag leaves, grains and at three developmental stages during grain filling. NFP plants showed increased sensitivity to iron-deficiency conditions and changes in the expression of endogenous genes involved in nicotianamine (NA metabolism, in comparison to their non-transgenic siblings. Elevated transcript levels were detected in NFP plants for several iron transporters. In contrast, expression of OsYSL2, which encodes a member of Yellow Stripe-like protein family, and a transporter of the NA-Fe(II complex was reduced in NFP plants under low iron conditions, indicating that expression of OsYSL2 is regulated by the endogenous iron status. Expression of the transgenes did not significantly affect overall iron homeostasis in NFP plants, which establishes the engineered push-pull mechanism as a suitable strategy to increase rice endosperm iron content.
Ternary silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and quaternary derivatives RERh{sub 4}Si{sub 2-x}Sn{sub x} (RE = Y, Nd, Sm, Gd-Lu) - structure, chemical bonding, and solid state NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Vosswinkel, Daniel; Benndorf, Christopher; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Sao Paulo Univ., Sao Carlos (Brazil). Inst. of Physics; Matar, Samir F. [Bordeaux Univ., CNRS, ICMCB, UPR 9048, Pessac (France)

2016-11-01

The silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and silicide stannides RERh{sub 4}Si{sub 2-x}Sn{sub x}(RE = Y, Nd, Sm, Gd-Lu) were synthesized from the elements by arc-melting and subsequent annealing. The new compounds crystallize with the orthorhombic YRh{sub 4}Ge{sub 2} type structure, space group Pnma. They were characterized by X-ray powder patterns and several structures were refined from single crystal X-ray diffractometer data. The main structural motifs of this series of silicides are tricapped trigonal prisms formed by the transition metal and rare earth atoms. One of the two crystallographically independent silicon sites allows for formation of solid solutions with tin, exemplarily studied for ErRh{sub 4}Si{sub 2-x}Sn{sub x}. Electronic structure calculations reveal strong covalent Rh-Si bonding as the main stability factor. Multinuclear ({sup 29}Si, {sup 45}Sc, and {sup 89}Y) magic-angle spinning (MAS) NMR spectra of the structure representatives with diamagnetic rare-earth elements (Sc, Y, Lu) are found to be consistent with the crystallographic data and specifically confirm the selective substitution of Sn in the Si2 sites in the quaternary compounds YRh{sub 4}SiSn and LuRh{sub 4}SiSn.
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... anemia, your doctor may order the following blood tests to diagnose iron-deficiency anemia: Complete blood count (CBC) to ... than normal when viewed under a microscope. Different tests help your doctor diagnose iron-deficiency anemia. In iron-deficiency anemia, blood ...
Efficacy of iron supplementation may be misinterpreted using conventional measures of iron status in iron-depleted, nonanemic women undergoing aerobic exercise training.

Science.gov (United States)

Pompano, Laura M; Haas, Jere D

2017-12-01

Background: Despite its known detrimental effects, iron deficiency remains the most common micronutrient deficiency in the world. Many interventions that aim to improve iron status involve physically active populations. Intense aerobic exercise training negatively affects iron status; however, the impact of regular moderate aerobic exercise on the effectiveness of iron supplementation remains unclear. Objective: This study aimed to determine whether aerobic training modifies the assessment of the effectiveness of iron supplementation in improving conventional iron status measures. Design: Seventy-two iron-depleted, nonanemic Chinese women [serum ferritin (sFer) 110 g/L] were included in an 8-wk, partially blinded, randomized controlled trial with a 2 × 2 factorial design including iron supplements (42 mg elemental Fe/d) or placebo and aerobic training (five 25-min sessions/wk at 75-85% of maximum heart rate) or no training. Linear mixed models were used to evaluate the relation between supplement type, training, and changes in iron status over time, measured by sFer, hemoglobin, soluble transferrin receptor (sTfR), and estimated total body iron. Results: After treatment, both the iron-supplemented trained and untrained groups showed significantly improved sFer, sTfR, and body iron values compared with either of the placebo groups. Similarly, trained participants had significantly higher aerobic fitness measures than untrained participants. Training modified the sFer response to supplementation (training by supplement interaction, P = 0.07), with the iron-supplemented trained group having significantly lower sFer than the iron-supplemented untrained group at week 8 (mean ± SD: 31.8 ± 13.5 and 47.6 ± 15.7 μg/L, respectively; P = 0.042), whereas there was no significant difference between the placebo trained and untrained groups (21.3 ± 12.2 and 20.3 ± 7.0 μg/L, respectively; P = 1.00). Conclusions: Regular aerobic training reduces the apparent effectiveness
Changes in serum iron, total iron binding capacity and transferrin ...

African Journals Online (AJOL)

Background: Iron is a vital constituent of cells but in excess may be harmful and is associated with a raised risk for some malignant diseases including breast cancer. We aimed to study changes in iron profile in Sudanese females newly diagnosed with breast cancer. Methods: A case- control study in which serum iron, Total ...
49 CFR 192.487 - Remedial measures: Distribution lines other than cast iron or ductile iron lines.

Science.gov (United States)

2010-10-01

... cast iron or ductile iron lines. 192.487 Section 192.487 Transportation Other Regulations Relating to... iron or ductile iron lines. (a) General corrosion. Except for cast iron or ductile iron pipe, each... the purpose of this paragraph. (b) Localized corrosion pitting. Except for cast iron or ductile iron...
The role of mitochondria in cellular iron-sulfur protein biogenesis and iron metabolism.

Science.gov (United States)

Lill, Roland; Hoffmann, Bastian; Molik, Sabine; Pierik, Antonio J; Rietzschel, Nicole; Stehling, Oliver; Uzarska, Marta A; Webert, Holger; Wilbrecht, Claudia; Mühlenhoff, Ulrich

2012-09-01

Mitochondria play a key role in iron metabolism in that they synthesize heme, assemble iron-sulfur (Fe/S) proteins, and participate in cellular iron regulation. Here, we review the latter two topics and their intimate connection. The mitochondrial Fe/S cluster (ISC) assembly machinery consists of 17 proteins that operate in three major steps of the maturation process. First, the cysteine desulfurase complex Nfs1-Isd11 as the sulfur donor cooperates with ferredoxin-ferredoxin reductase acting as an electron transfer chain, and frataxin to synthesize an [2Fe-2S] cluster on the scaffold protein Isu1. Second, the cluster is released from Isu1 and transferred toward apoproteins with the help of a dedicated Hsp70 chaperone system and the glutaredoxin Grx5. Finally, various specialized ISC components assist in the generation of [4Fe-4S] clusters and cluster insertion into specific target apoproteins. Functional defects of the core ISC assembly machinery are signaled to cytosolic or nuclear iron regulatory systems resulting in increased cellular iron acquisition and mitochondrial iron accumulation. In fungi, regulation is achieved by iron-responsive transcription factors controlling the expression of genes involved in iron uptake and intracellular distribution. They are assisted by cytosolic multidomain glutaredoxins which use a bound Fe/S cluster as iron sensor and additionally perform an essential role in intracellular iron delivery to target metalloproteins. In mammalian cells, the iron regulatory proteins IRP1, an Fe/S protein, and IRP2 act in a post-transcriptional fashion to adjust the cellular needs for iron. Thus, Fe/S protein biogenesis and cellular iron metabolism are tightly linked to coordinate iron supply and utilization. This article is part of a Special Issue entitled: Cell Biology of Metals. Copyright © 2012 Elsevier B.V. All rights reserved.
Ironing Out the Unconventional Mechanisms of Iron Acquisition and Gene Regulation in Chlamydia

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Nick D. Pokorzynski

2017-09-01

Full Text Available The obligate intracellular pathogen Chlamydia trachomatis, along with its close species relatives, is known to be strictly dependent upon the availability of iron. Deprivation of iron in vitro induces an aberrant morphological phenotype termed “persistence.” This persistent phenotype develops in response to various immunological and nutritional insults and may contribute to the development of sub-acute Chlamydia-associated chronic diseases in susceptible populations. Given the importance of iron to Chlamydia, relatively little is understood about its acquisition and its role in gene regulation in comparison to other iron-dependent bacteria. Analysis of the genome sequences of a variety of chlamydial species hinted at the involvement of unconventional mechanisms, being that Chlamydia lack many conventional systems of iron homeostasis that are highly conserved in other bacteria. Herein we detail past and current research regarding chlamydial iron biology in an attempt to provide context to the rapid progress of the field in recent years. We aim to highlight recent discoveries and innovations that illuminate the strategies involved in chlamydial iron homeostasis, including the vesicular mode of acquiring iron from the intracellular environment, and the identification of a putative iron-dependent transcriptional regulator that is synthesized as a fusion with a ABC-type transporter subunit. These recent findings, along with the noted absence of iron-related homologs, indicate that Chlamydia have evolved atypical approaches to the problem of iron homeostasis, reinvigorating research into the iron biology of this pathogen.
A comparison of the metallurgical behaviour of dispersion fuels with uranium silicides and U6Fe as dispersants

International Nuclear Information System (INIS)

Nazare, S.

1984-01-01

In the past few years metallurgical studies have been carried out to develop fuel dispersions with U-densities up to 7.0 Mg U m -3 . Uranium silicides have been considered to be the prime candidates as dispersants; U 6 Fe being a potential alternative on account of its higher U-density. The objective of this paper is to compare the metallurgical behaviour of these two material combinations with regard to the following aspects: (1) preparation of the compounds U 3 Si, U 3 Si 2 and U 6 Fe; (2) powder metallurgical processing to miniature fuel element plates; (3) reaction behaviour under equilibrium conditions in the relevant portions of the ternary U-Si-Al and U-Fe-Al systems; (4) dimensional stability of the fuel plates after prolonged thermal treatment; (5) thermochemical behaviour of fuel plates at temperatures near the melting point of the cladding. Based on this data, the possible advantages of each fuel combination are discussed. (author)
Synthesis, Characterization, and Mechanism of Formation of Janus-Like Nanoparticles of Tantalum Silicide-Silicon (TaSi2/Si

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Andrey V. Nomoev

2014-12-01

Full Text Available Metal-semiconductor Janus-like nanoparticles with the composition tantalum silicide-silicon (TaSi2/Si were synthesized for the first time by means of an evaporation method utilizing a high-power electron beam. The composition of the synthesized particles were characterized using high-resolution transmission electron microscopy (HRTEM, X-ray diffraction (XRD, selective area electron diffraction (SAED, and energy dispersive X-ray fluorescence (EDX analysis. The system is compared to previously synthesized core-shell type particles in order to show possible differences responsible for the Janus-like structure forming instead of a core-shell architecture. It is proposed that the production of Janus-like as opposed to core-shell or monophase particles occurs due to the ability of Ta and Si to form compounds and the relative content of Ta and Si atoms in the produced vapour. Based on the results, a potential mechanism of formation for the TaSi2/Si nanoparticles is discussed.
Iron-Air Rechargeable Battery

Science.gov (United States)

Narayan, Sri R. (Inventor); Prakash, G.K. Surya (Inventor); Kindler, Andrew (Inventor)

2014-01-01

Embodiments include an iron-air rechargeable battery having a composite electrode including an iron electrode and a hydrogen electrode integrated therewith. An air electrode is spaced from the iron electrode and an electrolyte is provided in contact with the air electrode and the iron electrodes. Various additives and catalysts are disclosed with respect to the iron electrode, air electrode, and electrolyte for increasing battery efficiency and cycle life.
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... supplements. Iron supplements can change how certain medicines work. Your doctor may suggest check-ups to make sure your ... To prevent complications from iron-deficiency anemia, your doctor may ... during certain stages of life when more iron is needed, such as childhood ...
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... if you are diagnosed with iron-deficiency anemia. Risk Factors You may have an increased risk for iron-deficiency anemia because of your age, ... or sex. Age You may be at increased risk for iron deficiency at certain ages: Infants between ...
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... normally stores but has used up. Increase your intake of vitamin C to help your body absorb iron. Avoid drinking black tea, which reduces iron absorption. Other treatments If you have chronic kidney disease and iron-deficiency anemia, your doctor may recommend ...
Determination of Iron Content in Iron Deficiency Drugs by UV-Visible Spectrophotometer

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Isam Eldin Hussein Elgailani

2017-07-01

Full Text Available The objective of this work was to validate a simple, precise and accurate spectrophotometric method for the determination of iron in the iron deficiency drugs, namely are Feroglobin B12, Ferose-F and Ferose. The proposed method is based on the reaction of iron with ammonium thiocyanate after the wet digestion of the drugs under study with HNO3 and H2O2. Effects of pH, temperature, standing time and thiocyanate concentration on the determination of iron in drugs containing iron have been investigated. The λmax was 430 nm and the molar absorptivity of 0.0399 L mol-1 cm-1. The linear regression was in the range 0.5 - 60 μg/mL for iron content in hemoglobin. The detection limit and the limit of quantification were found to be 0.040 and 0.122 µg mL-1 for the iron respectively, and with a linear regression correlation coefficient of 0.998. Recovery measurements ranged from 99.63-100.20%. This method is simple and fast can be used for the determination of iron in the iron deficiency drugs in pharmaceutical laboratories. DOI: http://dx.doi.org/10.17807/orbital.v9i3.953

On iron radionuclide interactions and in situ measurement of iron corrosion products

International Nuclear Information System (INIS)

Puranen, A.; Jonsson, M.; Cui, D.; Scheidegger, A.M.; Wersin, P.; Spahiu, K.

2005-01-01

Full text of publication follows: In performance assessments of hard rock repositories, it is conservatively assumed that waste canisters are breached and that the spent fuel will get into contact with groundwater after 1000 years. When the canister eventually fails to protect HLW from groundwater, dissolved radionuclides from HLW will react with iron canister materials. The reactivity will depend on the conditions in solution and at the iron-water interface. To improve our understanding on the redox chemistry at near field conditions, batch experiments are conducted by contacting polished iron foils with a synthetic groundwater solution containing 10 mM NaCl, 2 mM NaHCO 3 and 5 ppm Se(IV), Se(VI), Tc(VII) and U(VI) in a glove box filled with Ar + 0.03% CO 2 gas mixture. The reaction rates are measured by analysing Se, Tc and U concentrations by ICP-MS. Iron corrosion products formed during the reaction(s) is monitored in-situ by a Layer Raman spectrometer through an optical window. The corrosion potential of the iron foil as well as the Eh and pH values of the bulk solution are recorded continuously during the experiment. The reacted iron foil is embedded with EPOXY resin, and the cross section will be analysed by SEM-EDS and XAS. The preliminary experimental results shows that with the formation of iron green rust FeII 4 FeIII 2 (OH) 12 CO 3 on iron foil, the rates of redox reactions between iron and the negatively charged radionuclides species are increased. The observation is explained by the fact that radionuclide anionic species can be first adsorbed then reduced on the positively charged outer surface of iron green rust. The positive charge is a result of the electrical balance of the negative charges of carbonate contained between the layered iron hydroxides in the green rust. Reduced forms of radionuclides are identified in the iron corrosion products. The results suggest that the formation of iron green rust as a corrosion product on the surface of iron
Colour Metallography of Cast Iron - Chapter 3: Spheroidal Graphite Cast Iron (Ⅳ

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Zhou Jiyang

2010-11-01

Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour
Colour Metallography of Cast Iron - Chapter 3: Spheroidal Graphite Cast Iron (Ⅰ

Directory of Open Access Journals (Sweden)

Zhou Jiyang

2010-02-01

Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour
Colour Metallography of Cast Iron - Chapter 4: Vermicular Graphite Cast Iron (Ⅱ

Directory of Open Access Journals (Sweden)

Zhou Jiyang

2011-05-01

Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour
The obtaining of iron acetate from processed iron comprising catalyst of ammonia synthesis

International Nuclear Information System (INIS)

Mansurov, M.M.; Lugovenko, A.N.; Mirzoeva, M.M.

1993-01-01

Present article is devoted to obtaining of iron acetate from processed iron comprising catalyst of ammonia synthesis. The method of synthesis of iron acetate from processed iron comprising catalyst of ammonia synthesis was elaborated. The structure of complex was determined.
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... Topics News & Resources Intramural Research Home / < Back To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer ... and symptoms as well as complications from iron-deficiency anemia. Research for Your Health The NHLBI is part of the U.S. Department ...
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... iron-deficiency anemia, including: Vegetarian or vegan eating patterns. Not eating enough iron-rich foods, such as meat and fish, may result in you getting less than the recommended daily amount of iron. Frequent blood donation. Individuals who donate blood often may be ...
Characterization of atom clusters in irradiated pressure vessel steels and model alloys

International Nuclear Information System (INIS)

Auger, P.; Pareige, P.; Akamatsu, M.; Van Duysen, J.C.

1993-12-01

In order to characterize the microstructural evolution of the iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions and, for comparison, low copper model alloys irradiated with neutrons and electrons have been studied. The characterization has been carried out mainly thanks to small angle neutron scattering and atom probe experiments. Both techniques lead to the conclusion that clusters develop with irradiations. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex. Solute atoms like Ni, Mn and Si, sometimes associated with Cu, segregate as ''clouds'' more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs
Cytosolic iron chaperones: Proteins delivering iron cofactors in the cytosol of mammalian cells.

Science.gov (United States)

Philpott, Caroline C; Ryu, Moon-Suhn; Frey, Avery; Patel, Sarju

2017-08-04

Eukaryotic cells contain hundreds of metalloproteins that are supported by intracellular systems coordinating the uptake and distribution of metal cofactors. Iron cofactors include heme, iron-sulfur clusters, and simple iron ions. Poly(rC)-binding proteins are multifunctional adaptors that serve as iron ion chaperones in the cytosolic/nuclear compartment, binding iron at import and delivering it to enzymes, for storage (ferritin) and export (ferroportin). Ferritin iron is mobilized by autophagy through the cargo receptor, nuclear co-activator 4. The monothiol glutaredoxin Glrx3 and BolA2 function as a [2Fe-2S] chaperone complex. These proteins form a core system of cytosolic iron cofactor chaperones in mammalian cells. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.
Iron absorption from beans with different contents of iron, evaluated by stable isotopes.

Science.gov (United States)

Junqueira-Franco, Márcia Varella Morandi; Dutra de Oliveira, José Eduardo; Nutti, Marilia Regini; Pereira, Helton Santos; Carvalho, José Luiz Vianna de; Abrams, Steven A; Brandão, Camila Fernanda Cunha; Marchini, Júlio Sérgio

2018-06-01

The introduction of biofortified foods such as beans with higher iron content may be a useful tool in preventing iron deficiency. The biofortification aims to reach the root of the problem of malnutrition, targets the neediest population, uses embedded distribution mechanisms, is scientifically feasible and effective in terms of cost, and complements other ongoing interventions to control micronutrient deficiency. However, to ensure effectiveness, measurement of the absorption of minerals is essential. The objective of this study was to evaluate the iron bioavailability of common bean BRS Pontal (PO), targeted for biofortification, compared with common bean BRS Estilo in man through reliable techniques that have not been previously used in Brazil. The study included 29 young adult volunteers divided into 2 groups: Group CB (13 subjects) received 100 g of common beans (BRS-Estilo) cooked labeled with iron-58 ( 58 Fe) and Group TBB (16 patients) received 100 g common bean target for iron biofortification (BRS-Pontal), cooked and labeled with iron58 ( 58 Fe). The next day they received the reference dose of ferrous sulfate enriched iron-57 ( 57 Fe). Isotopic evaluation of iron for measurement of iron incorporation into erythrocytes was performed 14 days after consumption. The beans used, were produced, through conventional breeding program, by EMBRAPA/Rice and Beans. The iron absorption was evaluated by assessing the isotopic enrichment of the stable isotope. Mean iron absorption from the meal with common beans was 0.409% (±0.040%) and mean iron incorporation from the meal with target beans for biofortification 0.407% (±0.038%) and did not differ between the groups. This study tested the iron absorption from a single bean meal in healthy volunteers or non anemics, In the present study the iron absorption ratio from common bean Pontal (PO), targeted for biofortification and compared with common bean BRS Estilo was not significantly different. The iron concentration
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... This is sometimes used to deliver iron through a blood vessel to increase iron levels in the blood. One benefit of IV iron ... over 65 years of age had low hemoglobin levels. This was associated with a greater risk of death even with mild anemia. ...
Iron and Immunity

NARCIS (Netherlands)

Verbon, E.H.|info:eu-repo/dai/nl/413534049; Trapet, P.L.; Stringlis, I.|info:eu-repo/dai/nl/41185206X; Kruijs, Sophie; Bakker, P.A.H.M.|info:eu-repo/dai/nl/074744623; Pieterse, C.M.J.|info:eu-repo/dai/nl/113115113

2017-01-01

Iron is an essential nutrient for most life on Earth because it functions as a crucial redox catalyst in many cellular processes. However, when present in excess iron can lead to the formation of harmful hydroxyl radicals. Hence, the cellular iron balance must be tightly controlled. Perturbation of
49 CFR 192.369 - Service lines: Connections to cast iron or ductile iron mains.

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Connections to cast iron or ductile iron mains. 192.369 Section 192.369 Transportation Other Regulations Relating to Transportation... ductile iron mains. (a) Each service line connected to a cast iron or ductile iron main must be connected...
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... iron-fortified breads and cereals, peas, tofu, dried fruits, and dark green leafy vegetables. Foods rich in vitamin C, such as oranges, ... iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach and other dark green leafy vegetables. You can also take an iron supplement. Follow ...
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... Topics section only, or the News and Resources section. NHLBI Entire Site NHLBI Entire Site Health ... español Iron-deficiency anemia is a common type of anemia that occurs if you do not have enough iron in your body. People with mild or moderate iron-deficiency anemia ...
Effect of treatment with single total-dose intravenous iron versus daily oral iron(III-hydroxide polymaltose on moderate puerperal iron-deficiency anemia

Directory of Open Access Journals (Sweden)

Iyoke CA

2017-05-01

Full Text Available Chukwuemeka Anthony Iyoke,1 Fausta Chioma Emegoakor,1 Euzebus Chinonye Ezugwu,1 Lucky Osaheni Lawani,2 Leonard Ogbonna Ajah,1 Jude Anazoeze Madu,3 Hyginus Uzo Ezegwui,1 Frank Okechukwu Ezugwu4 1Department of Obstetrics and Gynaecology, University of Nigeria, Enugu Campus, 2Department of Obstetrics and Gynaecology, Federal Teaching Hospital, Abakaliki, 3Department of Haematology, University of Nigeria, Nsukka, 4Department of Obstetrics and Gynaecology, College of Medicine, Enugu State University, Enugu, Nigeria Background: Iron-deficiency anemia is the most common nutritional cause of anemia in pregnancy and is often responsible for puerperal anemia. Puerperal anemia can impair postpartum maternal and neonatal well-being. Objective: To determine the effect of treatment of moderate puerperal iron-deficiency anemia using a single intravenous total-dose iron dextran versus daily single dose oral iron(III-hydroxide polymaltose. Methodology: A randomized controlled study in which postpartum women with moderate iron-deficiency anemia were randomized into treatment with either a single total-dose intravenous iron dextran or with daily single doses of oral iron(III-hydroxide polymaltose tablets for 6 weeks. Effects on hemoglobin concentration using either method were compared at 6 weeks postpartum. Analysis was per protocol using SPSS version 17 for windows. P-values ≤0.05 were considered significant. Results: Two hundred eighty-four women were recruited for the study: 142 women received single total dose intravenous infusion of iron dextran while 142 received daily oral iron(III-hydroxide polymaltose tablets. Approximately 84.0% (237/282 completed the study and were analyzed including 81% (115/142 of those randomized to injectable iron therapy compared to 85.9% (122/142 of those randomized to oral treatment. The proportions of women who had attained hemoglobin concentration of at least 10 g/dL by the 6 weeks postpartum visit did not differ
The effect of nutrition knowledge and dietary iron intake on iron status in young women.

Science.gov (United States)

Leonard, Alecia J; Chalmers, Kerry A; Collins, Clare E; Patterson, Amanda J

2014-10-01

Previous research on the relationships between general nutrition knowledge and dietary intake, and dietary iron intake and iron status has produced inconsistent results. Currently, no study has focused on knowledge of dietary iron and its effect on dietary iron intake. This study aimed to determine whether nutrition knowledge of iron is related to dietary iron intake in young women, and subsequently whether greater knowledge and intake translates into better iron status. A cross-sectional assessment of nutrition knowledge of iron, dietary iron intake and iron status was conducted in women aged 18-35 years living in Newcastle, NSW, Australia. Iron status was assessed by serum ferritin, haemoglobin, soluble transferrin receptor and alpha-1-glycoprotein. One hundred and seven women (27.8 ± 4.7 years) completed the nutrition knowledge questionnaire and FFQ. Of these, 74 (70%) also had biomarkers of iron status measured. Mean iron intake was 11.2 ± 3.8 mg/day. There was no association between nutrition knowledge score and whether the women met the RDI for iron (F (1, 102) = .40, P = .53). A positive correlation was shown between nutrition knowledge score and iron intake (mg/day) (r = 0.25, P = .01). Serum ferritin was positively associated with the frequency of flesh food intake (r = .27 P = .02). Vegetarians (including partial vegetarians) had significantly lower serum ferritin levels than non-vegetarians (F (1, 71) = 7.44, P = .01). Significant positive correlations found between higher flesh food intake and biomarkers of iron status suggest that educating non-vegetarians about the benefits of increased flesh food consumption and vegetarians about dietary iron enhancers and inhibitors may have potential for addressing the high rates of iron deficiency among young women. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.
Combined Therapy of Iron Chelator and Antioxidant Completely Restores Brain Dysfunction Induced by Iron Toxicity

Science.gov (United States)

Sripetchwandee, Jirapas; Pipatpiboon, Noppamas; Chattipakorn, Nipon; Chattipakorn, Siriporn

2014-01-01

Background Excessive iron accumulation leads to iron toxicity in the brain; however the underlying mechanism is unclear. We investigated the effects of iron overload induced by high iron-diet consumption on brain mitochondrial function, brain synaptic plasticity and learning and memory. Iron chelator (deferiprone) and antioxidant (n-acetyl cysteine) effects on iron-overload brains were also studied. Methodology Male Wistar rats were fed either normal diet or high iron-diet consumption for 12 weeks, after which rats in each diet group were treated with vehicle or deferiprone (50 mg/kg) or n-acetyl cysteine (100 mg/kg) or both for another 4 weeks. High iron-diet consumption caused brain iron accumulation, brain mitochondrial dysfunction, impaired brain synaptic plasticity and cognition, blood-brain-barrier breakdown, and brain apoptosis. Although both iron chelator and antioxidant attenuated these deleterious effects, combined therapy provided more robust results. Conclusion In conclusion, this is the first study demonstrating that combined iron chelator and anti-oxidant therapy completely restored brain function impaired by iron overload. PMID:24400127
Intravenous iron treatments for iron deficiency anemia in inflammatory bowel disease: a budget impact analysis of iron isomaltoside 1000 (Monofer) in the UK.

Science.gov (United States)

Pollock, R F; Muduma, G

2017-12-01

Iron deficiency is the leading cause of anemia in patients with inflammatory bowel disease (IBD). Intravenous iron is the first-line treatment for clinically active IBD or previous oral iron intolerance. The aim of the present study was to develop a comparative model of iron deficiency and delivery for iron isomaltoside (IIM), ferric carboxymaltose (FCM), low molecular weight iron dextran (LMWID), and iron sucrose (IS) in the treatment of iron deficiency anemia associated with IBD. Areas covered: A model was developed to evaluate iron delivery characteristics, resource use and costs associated with IIM, FCM, LMWID and IS. Iron deficiency was modeled using dosing tables and retreatments were modeled based on a pooled retrospective analysis. The analyses were conducted over 5 years in patients with IBD with mean bodyweight of 75.4 kg and hemoglobin levels of 10.77 g/dL based on observational data. Expert opinion: The modeling analysis showed that using IIM required 1.2 infusions (per treatment) to correct the mean iron deficit, compared with 1.6, 1.2, and 7.1 with FCM, LMWID and IS, respectively. Costs were estimated to be 2,518 pounds sterling (GBP) per patient with IIM or LMWID, relative to GBP 3,309 with FCM or GBP 14,382 with IS.
Bioavailability & absorption of Iron and Anemia

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Radhika Kapil

2018-01-01

Full Text Available Humans derive iron from their everyday diet, predominantly from plant foods and the rest from foods of animal origin. Iron is found in food as either haem or non-haem iron. Haem iron, which is about up to 40 per cent of the iron in meat, poultry, and fish, is well absorbed. All the iron in plants (fruits, vegetables, grains, nuts is in the form of non-haem iron and is relatively poorly absorbed. Non-haem iron contributes about 90-95 per cent of total daily iron in vegan diets. In western countries,the intake of haem iron from meat and meat products accounts for bulk of the dietary iron. The haem iron consumption is minimal in developing countries with majority obtaining non-haem iron from cereals, pulses, vegetables and fruits'. The diets is plagued by low iron content and poor absorption. Major sources of non-haem iron are plant foods. The iron is chemically diverse, ranging from simple iron oxides and salts to more complex organic chelates such as hydroxyphosphates in phytoferritin(1.

Bioavailability & absorption of Iron and Anemia

Directory of Open Access Journals (Sweden)

Radhika Kapil

2017-12-01

Full Text Available Humans derive iron from their everyday diet, predominantly from plant foods and the rest from foods of animal origin. Iron is found in food as either haem or non-haem iron. Haem iron, which is about up to 40 per cent of the iron in meat, poultry, and fish, is well absorbed. All the iron in plants (fruits, vegetables, grains, nuts is in the form of non-haem iron and is relatively poorly absorbed. Non-haem iron contributes about 90-95 per cent of total daily iron in vegan diets. In western countries,the intake of haem iron from meat and meat products accounts for bulk of the dietary iron. The haem iron consumption is minimal in developing countries with majority obtaining non-haem iron from cereals, pulses, vegetables and fruits'. The diets is plagued by low iron content and poor absorption. Major sources of non-haem iron are plant foods. The iron is chemically diverse, ranging from simple iron oxides and salts to more complex organic chelates such as hydroxyphosphates in phytoferritin(1.
Efficacy of iron fortification compared to iron supplementation among Vietamese schoolchildren

NARCIS (Netherlands)

Le, Huong T.; Brouwer, I.D.; Burema, J.; NGuyen, K.C.; Kok, F.J.

2006-01-01

The effect of iron fortification is generally assumed to be less than iron supplementation; however, the magnitude of difference in effects is not known. The present study aims to compare the efficacy of these two strategies on anaemia and iron status. After screening on low Hb, 425 anaemic children
Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

DEFF Research Database (Denmark)

Scholz, Florian; Löscher, Carolin; Fiskal, Annika

2016-01-01

Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface...
Roentgenoelectronic investigation into oxidation of iron-chromium and iron-chromium-nickel alloys

International Nuclear Information System (INIS)

Akimov, A.G.; Rozenfel'd, I.L.; Kazanskij, L.P.; Machavariani, G.V.

1978-01-01

Kinetics of iron-chromium and iron-chromium-nickel alloy oxidation (of the Kh13 and Kh18N10T steels) in oxygen was investigated using X-ray electron spectroscopy. It was found that according to X-ray electron spectra chromium oxidation kinetics in the iron-chromium alloy differs significantly from oxidation kinetics of chromium pattern. Layer by layer X-ray electron analysis showed that chromium is subjected to a deeper oxidation as compared to iron, and accordingly, Cr 2 O 3 layer with pure iron impregnations is placed between the layer of mixed oxide (Fe 3 O 4 +Cr 2 O 3 ) and metal. A model of the iron-chromium alloy surface is suggested. The mixed oxide composition on the steel surface is presented as spinel Fesub(2+x)Crsub(1-x)Osub(y)
Iron, Anemia, and Iron Deficiency Anemia among Young Children in the United States

OpenAIRE

Gupta, Priya M.; Perrine, Cria G.; Mei, Zuguo; Scanlon, Kelley S.

2016-01-01

Iron deficiency and anemia are associated with impaired neurocognitive development and immune function in young children. Total body iron, calculated from serum ferritin and soluble transferrin receptor concentrations, and hemoglobin allow for monitoring of the iron and anemia status of children in the United States. The purpose of this analysis is to describe the prevalence of iron deficiency (ID), anemia, and iron deficiency anemia (IDA) among children 1–5 years using data from the 2007–201...
Therapeutic iron : Evaluation of methods to assess intravenous iron safety profiles and the development of a novel formulation for oral iron delivery

NARCIS (Netherlands)

Span, K.|info:eu-repo/dai/nl/357800842

2018-01-01

Iron treatment is necessary to replenish iron deficit due to several clinical conditions such as chronic diseases. However, as an excess of iron can result in redox imbalance resulting in oxidative stress and thus severe damage to tissue and organs, it is of utmost importance to develop iron
Proteomic analysis of iron acquisition, metabolic and regulatory responses of Yersinia pestis to iron starvation

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Fleischmann Robert D

2010-01-01

Full Text Available Abstract Background The Gram-negative bacterium Yersinia pestis is the causative agent of the bubonic plague. Efficient iron acquisition systems are critical to the ability of Y. pestis to infect, spread and grow in mammalian hosts, because iron is sequestered and is considered part of the innate host immune defence against invading pathogens. We used a proteomic approach to determine expression changes of iron uptake systems and intracellular consequences of iron deficiency in the Y. pestis strain KIM6+ at two physiologically relevant temperatures (26°C and 37°C. Results Differential protein display was performed for three Y. pestis subcellular fractions. Five characterized Y. pestis iron/siderophore acquisition systems (Ybt, Yfe, Yfu, Yiu and Hmu and a putative iron/chelate outer membrane receptor (Y0850 were increased in abundance in iron-starved cells. The iron-sulfur (Fe-S cluster assembly system Suf, adapted to oxidative stress and iron starvation in E. coli, was also more abundant, suggesting functional activity of Suf in Y. pestis under iron-limiting conditions. Metabolic and reactive oxygen-deactivating enzymes dependent on Fe-S clusters or other iron cofactors were decreased in abundance in iron-depleted cells. This data was consistent with lower activities of aconitase and catalase in iron-starved vs. iron-rich cells. In contrast, pyruvate oxidase B which metabolizes pyruvate via electron transfer to ubiquinone-8 for direct utilization in the respiratory chain was strongly increased in abundance and activity in iron-depleted cells. Conclusions Many protein abundance differences were indicative of the important regulatory role of the ferric uptake regulator Fur. Iron deficiency seems to result in a coordinated shift from iron-utilizing to iron-independent biochemical pathways in the cytoplasm of Y. pestis. With growth temperature as an additional variable in proteomic comparisons of the Y. pestis fractions (26°C and 37°C, there was
Modelling Systemic Iron Regulation during Dietary Iron Overload and Acute Inflammation: Role of Hepcidin-Independent Mechanisms.

Science.gov (United States)

Enculescu, Mihaela; Metzendorf, Christoph; Sparla, Richard; Hahnel, Maximilian; Bode, Johannes; Muckenthaler, Martina U; Legewie, Stefan

2017-01-01

Systemic iron levels must be maintained in physiological concentrations to prevent diseases associated with iron deficiency or iron overload. A key role in this process plays ferroportin, the only known mammalian transmembrane iron exporter, which releases iron from duodenal enterocytes, hepatocytes, or iron-recycling macrophages into the blood stream. Ferroportin expression is tightly controlled by transcriptional and post-transcriptional mechanisms in response to hypoxia, iron deficiency, heme iron and inflammatory cues by cell-autonomous and systemic mechanisms. At the systemic level, the iron-regulatory hormone hepcidin is released from the liver in response to these cues, binds to ferroportin and triggers its degradation. The relative importance of individual ferroportin control mechanisms and their interplay at the systemic level is incompletely understood. Here, we built a mathematical model of systemic iron regulation. It incorporates the dynamics of organ iron pools as well as regulation by the hepcidin/ferroportin system. We calibrated and validated the model with time-resolved measurements of iron responses in mice challenged with dietary iron overload and/or inflammation. The model demonstrates that inflammation mainly reduces the amount of iron in the blood stream by reducing intracellular ferroportin transcription, and not by hepcidin-dependent ferroportin protein destabilization. In contrast, ferroportin regulation by hepcidin is the predominant mechanism of iron homeostasis in response to changing iron diets for a big range of dietary iron contents. The model further reveals that additional homeostasis mechanisms must be taken into account at very high dietary iron levels, including the saturation of intestinal uptake of nutritional iron and the uptake of circulating, non-transferrin-bound iron, into liver. Taken together, our model quantitatively describes systemic iron metabolism and generated experimentally testable predictions for additional
Rethinking Iron Regulation and Assessment in Iron Deficiency, Anemia of Chronic Disease, and Obesity: Introducing Hepcidin

Science.gov (United States)

Tussing-Humphreys, Lisa; Pustacioglu, Cenk; Nemeth, Elizabeta; Braunschweig, Carol

2012-01-01

Adequate iron availability is essential to human development and overall health. Iron is a key component of oxygen-carrying proteins, has a pivotal role in cellular metabolism, and is essential to cell growth and differentiation. Inadequate dietary iron intake, chronic and acute inflammatory conditions, and obesity are each associated with alterations in iron homeostasis. Tight regulation of iron is necessary because iron is highly toxic and human beings can only excrete small amounts through sweat, skin and enterocyte sloughing, and fecal and menstrual blood loss. Hepcidin, a small peptide hormone produced mainly by the liver, acts as the key regulator of systemic iron homeostasis. Hepcidin controls movement of iron into plasma by regulating the activity of the sole known iron exporter ferroportin-1. Downregulation of the ferroportin-1 exporter results in sequestration of iron within intestinal enterocytes, hepatocytes, and iron-storing macrophages reducing iron bioavailability. Hepcidin expression is increased by higher body iron levels and inflammation and decreased by anemia and hypoxia. Importantly, existing data illustrate that hepcidin may play a significant role in the development of several iron-related disorders, including the anemia of chronic disease and the iron dysregulation observed in obesity. Therefore, the purpose of this article is to discuss iron regulation, with specific emphasis on systemic regulation by hepcidin, and examine the role of hepcidin within several disease states, including iron deficiency, anemia of chronic disease, and obesity. The relationship between obesity and iron depletion and the clinical assessment of iron status will also be reviewed. PMID:22717199
Prenatal Iron Supplementation Reduces Maternal Anemia, Iron Deficiency, and Iron Deficiency Anemia in a Randomized Clinical Trial in Rural China, but Iron Deficiency Remains Widespread in Mothers and Neonates.

Science.gov (United States)

Zhao, Gengli; Xu, Guobin; Zhou, Min; Jiang, Yaping; Richards, Blair; Clark, Katy M; Kaciroti, Niko; Georgieff, Michael K; Zhang, Zhixiang; Tardif, Twila; Li, Ming; Lozoff, Betsy

2015-08-01

Previous trials of prenatal iron supplementation had limited measures of maternal or neonatal iron status. The purpose was to assess effects of prenatal iron-folate supplementation on maternal and neonatal iron status. Enrollment occurred June 2009 through December 2011 in Hebei, China. Women with uncomplicated singleton pregnancies at ≤20 wk gestation, aged ≥18 y, and with hemoglobin ≥100 g/L were randomly assigned 1:1 to receive daily iron (300 mg ferrous sulfate) or placebo + 0.40 mg folate from enrollment to birth. Iron status was assessed in maternal venous blood (at enrollment and at or near term) and cord blood. Primary outcomes were as follows: 1) maternal iron deficiency (ID) defined in 2 ways as serum ferritin (SF) iron (BI) anemia [ID + anemia (IDA); hemoglobin 118 μmol/mol). A total of 2371 women were randomly assigned, with outcomes for 1632 women or neonates (809 placebo/folate, 823 iron/folate; 1579 mother-newborn pairs, 37 mothers, 16 neonates). Most infants (97%) were born at term. At or near term, maternal hemoglobin was significantly higher (+5.56 g/L) for iron vs. placebo groups. Anemia risk was reduced (RR: 0.53; 95% CI: 0.43, 0.66), as were risks of ID (RR: 0.74; 95% CI: 0.69, 0.79 by SF; RR: 0.65; 95% CI: 0.59, 0.71 by BI) and IDA (RR: 0.49; 95% CI: 0.38, 0.62 by SF; RR: 0.51; 95% CI: 0.40, 0.65 by BI). Most women still had ID (66.8% by SF, 54.7% by BI). Adverse effects, all minor, were similar by group. There were no differences in cord blood iron measures; >45% of neonates in each group had ID. However, dose-response analyses showed higher cord SF with more maternal iron capsules reported being consumed (β per 10 capsules = 2.60, P iron supplementation reduced anemia, ID, and IDA in pregnant women in rural China, but most women and >45% of neonates had ID, regardless of supplementation. This trial was registered at clinicaltrials.gov as NCT02221752. © 2015 American Society for Nutrition.
Moessbauer study on the distribution of iron vacancies in iron sulfide Fe sub(1-x)S

International Nuclear Information System (INIS)

Igaki, Kenzo; Sato, Masaki; Shinohara, Takeshi.

1982-01-01

The distribution of iron vacancies in iron sulfide Fe sub(1-x)S with the controlled compositions was investigated by Moessbauer spectroscopy at room temperature. Moessbauer spectrum was composed of several component spectra. These component spectra were assigned to the iron atoms with different configurations of neighboring iron vacancies. Judging from the composition dependence of intensity of each component, iron vacancies are considered to lie in every second iron layer for specimens with x between 0.125 and 0.10. For specimens with x between 0.10 and 0.09, this arrangement is nearly kept in the sample quenched from a higher temperature than 473 K, but after annealing at a lower temperature than 473 K iron vacancies are considered to lie not only in every second iron layer but also in every third iron layer or in adjacent iron layers. The iron vacancy arrangement lying in every third iron layer or in adjacent iron layers tends to dominate for specimens with x below 0.09. (author)
Facile and sustainable synthesis of shaped iron oxide nanoparticles: effect of iron precursor salts on the shapes of iron oxides.

Science.gov (United States)

Sayed, Farheen N; Polshettiwar, Vivek

2015-05-05

A facile and sustainable protocol for synthesis of six different shaped iron oxides is developed. Notably, all the six shapes of iron oxides can be synthesised using exactly same synthetic protocol, by simply changing the precursor iron salts. Several of the synthesised shapes are not reported before. This novel protocol is relatively easy to implement and could contribute to overcome the challenge of obtaining various shaped iron oxides in economical and sustainable manner.
Oxidation of Dodecanoate Intercalated Iron(II)–Iron(III) Layered Double Hydroxide to Form 2D Iron(III) (Hydr)oxide Layers

DEFF Research Database (Denmark)

Huang, Li‐Zhi; Ayala‐Luis, Karina B.; Fang, Liping

2013-01-01

hydroxide planar layer were preserved during the oxidation, as shown by FTIR spectroscopy. The high positive charge in the hydroxide layer produced by the oxidation of iron(II) to iron(III) is partially compensated by the deprotonation of hydroxy groups, as shown by X‐ray photoelectron spectroscopy...... between the alkyl chains of the intercalated dodecanoate anions play a crucial role in stabilizing the structure and hindering the collapse of the iron(II)–iron(III) (hydr)oxide structure during oxidation. This is the first report describing the formation of a stable planar layered octahedral iron......(III) (hydr)oxide. oxGRC12 shows promise as a sorbent and host for hydrophobic reagents, and as a possible source of single planar layers of iron(III) (hydr)oxide....
Iron contents of Malawian foods when prepared in iron cooking pots

NARCIS (Netherlands)

Prinsen Geerligs, P. D.; Brabin, B. J.; Hart, D. J.; Fairweather-Tait, S. J.

2004-01-01

The aim of this study was to determine the iron content of Malawian foods prepared in iron pots and to examine the effects of continuous cooking time and added oil on the iron content of the food prepared. Foods prepared, which included a staple (Nsima), relish vegetables, and beans, had an
Co-regulation of Iron Metabolism and Virulence Associated Functions by Iron and XibR, a Novel Iron Binding Transcription Factor, in the Plant Pathogen Xanthomonas.

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Sheo Shankar Pandey

2016-11-01

Full Text Available Abilities of bacterial pathogens to adapt to the iron limitation present in hosts is critical to their virulence. Bacterial pathogens have evolved diverse strategies to coordinately regulate iron metabolism and virulence associated functions to maintain iron homeostasis in response to changing iron availability in the environment. In many bacteria the ferric uptake regulator (Fur functions as transcription factor that utilize ferrous form of iron as cofactor to regulate transcription of iron metabolism and many cellular functions. However, mechanisms of fine-tuning and coordinated regulation of virulence associated function beyond iron and Fur-Fe2+ remain undefined. In this study, we show that a novel transcriptional regulator XibR (named Xanthomonas iron binding regulator of the NtrC family, is required for fine-tuning and co-coordinately regulating the expression of several iron regulated genes and virulence associated functions in phytopathogen Xanthomonas campestris pv. campestris (Xcc. Genome wide expression analysis of iron-starvation stimulon and XibR regulon, GUS assays, genetic and functional studies of xibR mutant revealed that XibR positively regulates functions involved in iron storage and uptake, chemotaxis, motility and negatively regulates siderophore production, in response to iron. Furthermore, chromatin immunoprecipitation followed by quantitative real-time PCR indicated that iron promoted binding of the XibR to the upstream regulatory sequence of operon's involved in chemotaxis and motility. Circular dichroism spectroscopy showed that purified XibR bound ferric form of iron. Electrophoretic mobility shift assay revealed that iron positively affected the binding of XibR to the upstream regulatory sequences of the target virulence genes, an effect that was reversed by ferric iron chelator deferoxamine. Taken together, these data revealed that how XibR coordinately regulates virulence associated and iron metabolism functions in
Co-regulation of Iron Metabolism and Virulence Associated Functions by Iron and XibR, a Novel Iron Binding Transcription Factor, in the Plant Pathogen Xanthomonas

Science.gov (United States)

Pandey, Sheo Shankar; Patnana, Pradeep Kumar; Lomada, Santosh Kumar; Tomar, Archana; Chatterjee, Subhadeep

2016-01-01

Abilities of bacterial pathogens to adapt to the iron limitation present in hosts is critical to their virulence. Bacterial pathogens have evolved diverse strategies to coordinately regulate iron metabolism and virulence associated functions to maintain iron homeostasis in response to changing iron availability in the environment. In many bacteria the ferric uptake regulator (Fur) functions as transcription factor that utilize ferrous form of iron as cofactor to regulate transcription of iron metabolism and many cellular functions. However, mechanisms of fine-tuning and coordinated regulation of virulence associated function beyond iron and Fur-Fe2+ remain undefined. In this study, we show that a novel transcriptional regulator XibR (named X anthomonas iron binding regulator) of the NtrC family, is required for fine-tuning and co-coordinately regulating the expression of several iron regulated genes and virulence associated functions in phytopathogen Xanthomonas campestris pv. campestris (Xcc). Genome wide expression analysis of iron-starvation stimulon and XibR regulon, GUS assays, genetic and functional studies of xibR mutant revealed that XibR positively regulates functions involved in iron storage and uptake, chemotaxis, motility and negatively regulates siderophore production, in response to iron. Furthermore, chromatin immunoprecipitation followed by quantitative real-time PCR indicated that iron promoted binding of the XibR to the upstream regulatory sequence of operon’s involved in chemotaxis and motility. Circular dichroism spectroscopy showed that purified XibR bound ferric form of iron. Electrophoretic mobility shift assay revealed that iron positively affected the binding of XibR to the upstream regulatory sequences of the target virulence genes, an effect that was reversed by ferric iron chelator deferoxamine. Taken together, these data revealed that how XibR coordinately regulates virulence associated and iron metabolism functions in Xanthomonads in
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... Heart and Vascular Diseases Precision Medicine Activities Obesity, Nutrition, and Physical Activity Population and Epidemiology Studies Women’s ... making new blood cells. Visit our Aplastic Anemia Health Topic to learn more. ... recommend that you take iron supplements, also called iron pills or oral iron, by mouth once or several times a ...
Construction of a four tip scanning tunneling microscope/scanning electron microscope combination and conductivity measurements of silicide nanowires; Aufbau einer Vierspitzen-Rastertunnelmikroskop/Rasterelektronenmikroskop-Kombination und Leitfaehigkeitsmessungen an Silizid Nanodraehten

Energy Technology Data Exchange (ETDEWEB)

Zubkov, Evgeniy

2013-09-01

In this work the combination of a four-tip scanning tunneling microscope with a scanning electron microscope is presented. By means of this apparatus it is possible to perform the conductivity measurements on the in-situ prepared nanostructures in ultra-high vacuum. With the aid of a scanning electron microscope (SEM), it becomes possible to position the tunneling tips of the four-tip scanning tunneling microscope (STM), so that an arrangement for a four-point probe measurement on nanostructures can be obtained. The STM head was built according to the novel coaxial Beetle concept. This concept allows on the one hand, a very compact arrangement of the components of the STM and on the other hand, the new-built STM head has a good mechanical stability, in order to achieve atomic resolution with all four STM units. The atomic resolution of the STM units was confirmed by scanning a Si(111)-7 x 7 surface. The thermal drift during the STM operation, as well as the resonant frequencies of the mechanical structure of the STM head, were determined. The scanning electron microscope allows the precise and safe navigation of the tunneling tips on the sample surface. Multi tip spectroscopy with up to four STM units can be performed synchronously. To demonstrate the capabilities of the new-built apparatus the conductivity measurements were carried out on metallic yttrium silicide nanowires. The nanowires were prepared by the in-situ deposition of yttrium on a heated Si(110) sample surface. Current-voltage curves were recorded on the nanowires and on the wetting layer in-between. The curves indicate an existence of the Schottky barrier between the yttrium silicide nanowires and the silicon bulk. By means of the two-tip measurements with a gate, the insulating property of the Schottky barrier has been confirmed. Using this Schottky barrier, it is possible to limit the current to the nanowire and to prevent it from flowing through the silicon bulk. A four-tip resistance measurement
Development of silicide coating over molybdenum based refractory alloy and its characterization

International Nuclear Information System (INIS)

Chakraborty, S.P.; Banerjee, S.; Sharma, I.G.; Suri, A.K.

2010-01-01

Molybdenum based refractory alloys are potential candidate materials for structural applications in high temperature compact nuclear reactors and fusion reactors. However, these alloys being highly susceptible to oxidation in air or oxygen at elevated temperature, undergoes severe losses from highly volatile molybdenum trioxide species. Present investigation, therefore, examines the feasibility of development of silicide type of coating over molybdenum base TZM alloy shape (Mo > 99 wt.%) using pack cementation coating technique. TZM alloy was synthesized in this laboratory from oxide intermediates of MoO 2 , TiO 2 and ZrO 2 in presence of requisite amount of carbon, by alumino-thermic reduction smelting technique. The arc melted and homogenized samples of TZM alloy substrate was then embedded in the chosen and intimately mixed pack composition consisting of inert matrix (Al 2 O 3 ), coating powder (Si) and activator (NH 4 Cl) taken in the judicious proportion. The sealed charge packs contained in an alumina crucible were heated at temperatures of 1000 o C for 8-16 h heating cycle to develop the coating. The coating phase was confirmed to be of made of MoSi 2 by XRD analysis. The morphology of the coating was studied by SEM characterization. It had revealed that the coating was diffusion bonded where Si from coating diffused inward and Mo from TZM substrate diffused outward to form the coating. The coating was found to be resistant to oxidation when tested in air up to 1200 o C. A maximum 100 μm of coating thickness was achieved on each side of the substrate.
Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

Science.gov (United States)

Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

2016-05-03

A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

Direct Iron Coating onto Nd-Fe-B Powder by Thermal Decomposition of Iron Pentacarbonyl

International Nuclear Information System (INIS)

Yamamuro, S; Okano, M; Tanaka, T; Sumiyama, K; Nozawa, N; Nishiuchi, T; Hirosawa, S; Ohkubo, T

2011-01-01

Iron-coated Nd-Fe-B composite powder was prepared by thermal decomposition of iron pentacarbonyl in an inert organic solvent in the presence of alkylamine. Though this method is based on a modified solution-phase process to synthesize highly size-controlled iron nanoparticles, it is in turn featured by a suppressed formation of iron nanoparticles to achieve an efficient iron coating solely onto the surfaces of rare-earth magnet powder. The Nd-Fe-B magnetic powder was successfully coated by iron shells whose thicknesses were of the order of submicrometer to micrometer, being tuneable by the amount of initially loaded iron pentacarbonyl in a reaction flask. The amount of the coated iron reached to more than 10 wt.% of the initial Nd-Fe-B magnetic powder, which is practically sufficient to fabricate Nd-Fe-B/α-Fe nanocomposite permanent magnets.
Corrosion behavior of austempered ductile iron (ADI) in iron ore slurry

African Journals Online (AJOL)

Corrosion behavior of austempered ductile iron (ADI) in iron ore slurry was studied as a function of the microstructure developed by austempering at 380 and 300°C for different exposure time in the slurry. The corrosion rates of the ADI balls immersed in the iron ore slurry was determined using weight loss method.
Iron replacement therapy

DEFF Research Database (Denmark)

Nielsen, Ole Haagen; Coskun, Mehmet; Weiss, Günter

2016-01-01

PURPOSE OF REVIEW: Approximately, one-third of the world's population suffers from anemia, and at least half of these cases are because of iron deficiency. With the introduction of new intravenous iron preparations over the last decade, uncertainty has arisen when these compounds should...... be administered and under which circumstances oral therapy is still an appropriate and effective treatment. RECENT FINDINGS: Numerous guidelines are available, but none go into detail about therapeutic start and end points or how iron-deficiency anemia should be best treated depending on the underlying cause...... of iron deficiency or in regard to concomitant underlying or additional diseases. SUMMARY: The study points to major issues to be considered in revisions of future guidelines for the true optimal iron replacement therapy, including how to assess the need for treatment, when to start and when to stop...
Females Are Protected From Iron-Overload Cardiomyopathy Independent of Iron Metabolism: Key Role of Oxidative Stress.

Science.gov (United States)

Das, Subhash K; Patel, Vaibhav B; Basu, Ratnadeep; Wang, Wang; DesAulniers, Jessica; Kassiri, Zamaneh; Oudit, Gavin Y

2017-01-23

Sex-related differences in cardiac function and iron metabolism exist in humans and experimental animals. Male patients and preclinical animal models are more susceptible to cardiomyopathies and heart failure. However, whether similar differences are seen in iron-overload cardiomyopathy is poorly understood. Male and female wild-type and hemojuvelin-null mice were injected and fed with a high-iron diet, respectively, to develop secondary iron overload and genetic hemochromatosis. Female mice were completely protected from iron-overload cardiomyopathy, whereas iron overload resulted in marked diastolic dysfunction in male iron-overloaded mice based on echocardiographic and invasive pressure-volume analyses. Female mice demonstrated a marked suppression of iron-mediated oxidative stress and a lack of myocardial fibrosis despite an equivalent degree of myocardial iron deposition. Ovariectomized female mice with iron overload exhibited essential pathophysiological features of iron-overload cardiomyopathy showing distinct diastolic and systolic dysfunction, severe myocardial fibrosis, increased myocardial oxidative stress, and increased expression of cardiac disease markers. Ovariectomy prevented iron-induced upregulation of ferritin, decreased myocardial SERCA2a levels, and increased NCX1 levels. 17β-Estradiol therapy rescued the iron-overload cardiomyopathy in male wild-type mice. The responses in wild-type and hemojuvelin-null female mice were remarkably similar, highlighting a conserved mechanism of sex-dependent protection from iron-overload-mediated cardiac injury. Male and female mice respond differently to iron-overload-mediated effects on heart structure and function, and females are markedly protected from iron-overload cardiomyopathy. Ovariectomy in female mice exacerbated iron-induced myocardial injury and precipitated severe cardiac dysfunction during iron-overload conditions, whereas 17β-estradiol therapy was protective in male iron-overloaded mice. �
Neutronic Analysis of the RSG-GAS Compact Core without CIP Silicide 3.55 g U/cc and 4.8 g U/cc

International Nuclear Information System (INIS)

Jati S; Lily S; Tukiran S

2004-01-01

Fuel conversion from U 3 O 8 -Al to U 3 Si 2 -Al 2.96 g U/cc density in the RSG-GAS core had done successfully step by step since 36 th core until 44 th core. So that, since the 45 th core until now (48 th core) had been using full of silicide 2.96 g U/cc. Even though utilization program of silicide fuel with high density (3.55 g U/cc and 4.8 g U/cc) and optimize operation of RSG-GAS core under research. Optimalitation of core with increasing operation cycle have been analyzing about compact core. The mean of compact core is the RSG-GAS core with decrease number of IP or CIP position irradiation. In this research, the neutronic calculation to cover RSG-GAS core and RSG-GAS core without CIP that are using U 3 Si 2 -Al 2.96 g U/cc, 3.55 g U/cc and 4.8 g U/cc had done. Two core calculation done at 15 MW power using SRAC-ASMBURN code. The calculation result show that fuel conversion from 2.96 g U/cc density to 3.55 g U/cc and 4.8 g U/cc will increasing cycle length for both RSG-GAS core and RSG-GAS compact core without CIP. However, increasing of excess reactivity exceeded from nominal value of first design that 9.2%. Change of power peaking factor is not show significant value and still less than 1.4. Core fuelled with U 3 Si 2 -Al 4.8 g U/cc density have maximum discharge burn-up which exceeded from licensing value (70%). RSG-GAS compact core without CIP fuelled U 3 Si 2 -Al 2.96 g U/cc have longer cycle operation then RSG-GAS core and fulfil limitation neutronic parameter at the first design value. (author)
A budget impact analysis of parenteral iron treatments for iron deficiency anemia in the UK: reduced resource utilization with iron isomaltoside 1000

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Pollock RF

2017-08-01

Full Text Available Richard F Pollock,1 Gorden Muduma2 1Ossian Health Economics and Communications GmbH, Basel, Switzerland; 2Pharmacosmos A/S, Holbaek, Denmark Background and aims: The reported prevalence of iron deficiency anemia (IDA varies widely but estimates suggest that 3% of men and 8% of women have IDA in the UK. Parenteral iron is indicated for patients intolerant or unresponsive to oral iron or requiring rapid iron replenishment. This study evaluated differences in the cost of treating these patients with iron isomaltoside (Monofer®, IIM relative to other intravenous iron formulations. Methods: A budget impact model was developed to evaluate the cost of using IIM relative to ferric carboxymaltose (Ferinject®, FCM, low molecular weight iron dextran (Cosmofer®, LMWID, and iron sucrose (Venofer®, IS in patients with IDA. To establish iron need, iron deficits were modeled using a simplified dosing table. The base case analysis was conducted over 1 year in patients with IDA with mean bodyweight of 82.4 kg (SD 22.5 kg and hemoglobin levels of 9.99 g/dL (SD 1.03 g/dL based on an analysis of patient characteristics in IDA trials. Costs were modeled using UK health care resource groups. Results: Using IIM required 1.3 infusions to correct the mean iron deficit, compared with 1.3, 1.8, and 7.7 with LMWID, FCM, and IS, respectively. Patients using IIM required multiple infusions in 35% of cases, compared with 35%, 77%, and 100% of patients with LMWID, FCM, and IS, respectively. Total costs were estimated to be GBP 451 per patient with IIM or LMWID, relative to GBP 594 with FCM (a GBP 143 or 24% saving with IIM or GBP 2,600 with IS (a GBP 2,149 or 83% saving with IIM. Conclusion: Using IIM or LMWID in place of FCM or IS resulted in a marked reduction in the number of infusions required to correct iron deficits in patients with IDA. The reduction in infusions was accompanied by substantial reductions in cost relative to FCM and IS over 1 year. Keywords: iron
Iron deficiency and cognitive functions

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Jáuregui-Lobera I

2014-11-01

Full Text Available Ignacio Jáuregui-Lobera Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain Abstract: Micronutrient deficiencies, especially those related to iodine and iron, are linked to different cognitive impairments, as well as to potential long-term behavioral changes. Among the cognitive impairments caused by iron deficiency, those referring to attention span, intelligence, and sensory perception functions are mainly cited, as well as those associated with emotions and behavior, often directly related to the presence of iron deficiency anemia. In addition, iron deficiency without anemia may cause cognitive disturbances. At present, the prevalence of iron deficiency and iron deficiency anemia is 2%–6% among European children. Given the importance of iron deficiency relative to proper cognitive development and the alterations that can persist through adulthood as a result of this deficiency, the objective of this study was to review the current state of knowledge about this health problem. The relevance of iron deficiency and iron deficiency anemia, the distinction between the cognitive consequences of iron deficiency and those affecting specifically cognitive development, and the debate about the utility of iron supplements are the most relevant and controversial topics. Despite there being methodological differences among studies, there is some evidence that iron supplementation improves cognitive functions. Nevertheless, this must be confirmed by means of adequate follow-up studies among different groups. Keywords: iron deficiency, anemia, cognitive functions, supplementation
Milk iron content in breast-feeding mothers after administration of intravenous iron sucrose complex.

Science.gov (United States)

Breymann, Christian; von Seefried, Bettina; Stahel, Michele; Geisser, Peter; Canclini, Camillo

2007-01-01

To study the transfer of parenteral iron sucrose into maternal milk in the postpartum period. Ten healthy lactating mothers with functional iron deficiency 2-3 days after delivery received 100 mg intravenous iron sucrose and were observed together with a control group (n=5) without iron treatment during four days. Milk samples were taken before the treatment and every day afterwards. Mean milk iron levels at baseline were 0.43 and 0.46 mg/kg in the treatment and control group and decreased until the end of observation in both groups by 0.11 mg/kg. No significant difference between the groups was found on any study day as well as in the mean change from baseline over all four days. We could not show transfer of iron-sucrose into maternal milk for the given dosage. Since parenteral iron sucrose is widely used in obstetrics, the results provide information about safety of parenteral iron sucrose in the lactation period. The findings are also in agreement with other reports on active biological mammary gland regulation of milk iron concentration.
Iron-Deficiency Anemia

Medline Plus

Full Text Available ... amounts of iron, in milligrams (mg) at different ages and stages of life. Until the teen years, the recommended amount of iron is the same for boys and girls. From birth to 6 months, babies need 0.27 mg of iron. This number goes up to 11 mg for children ages 7 to 12 months, and down to 7 ...
Iron nutrition and premenopausal women: effects of poor iron status on physical and neuropsychological performance.

Science.gov (United States)

McClung, James P; Murray-Kolb, Laura E

2013-01-01

Iron is a nutritionally essential trace element that functions through incorporation into proteins and enzymes, many of which contribute to physical and neuropsychological performance. Poor iron status, including iron deficiency (ID; diminished iron stores) and iron deficiency anemia (IDA; poor iron stores and diminished hemoglobin), affects billions of people worldwide. This review focuses on physical and neuropsychological outcomes associated with ID and IDA in premenopausal women, as the prevalence of ID and IDA is often greater in premenopausal women than other population demographics. Recent studies addressing the physiological effects of poor iron status on physical performance, including work productivity, voluntary activity, and athletic performance, are addressed. Similarly, the effects of iron status on neurological performance, including cognition, affect, and behavior, are summarized. Nutritional countermeasures for the prevention of poor iron status and the restoration of decrements in performance outcomes are described.
Adiposity in women and children from transition countries predicts decreased iron absorption, iron deficiency and a reduced response to iron fortification

NARCIS (Netherlands)

Zimmermann, M.B.; Zeder, C.; Muthayya, S.; Winichagoon, P.; Chaouki, N.; Aeberli, I.; Hurrell, R.F.

2008-01-01

Background: Overweight is increasing in transition countries, while iron deficiency remains common. In industrialized countries, greater adiposity increases risk of iron deficiency. Higher hepcidin levels in obesity may reduce dietary iron absorption. Therefore, we investigated the association
One step paired electrochemical synthesis of iron and iron oxide nanoparticles

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Ordoukhanian Juliet

2016-09-01

Full Text Available In this study, a new one step paired electrochemical method is developed for simultaneous synthesis of iron and iron oxide nanoparticles. iron and iron oxide are prepared as cathodic and anodic products from iron (ii sulfate aqueous solution in a membrane divided electrolytic cell by the pulsed current electrosynthesis. Because of organic solvent-free and electrochemical nature of the synthesis, the process could be considered as green and environmentally friendly. The reduction of energy consumption and low cost are the other significant advantages of this new method that would have a great application potential in the chemical industry. The nanostructure of prepared samples was characterized by Fourier transform infrared spectroscopy (FT-IR, X-ray diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The magnetic properties were studied by vibrating sample magnetometer (VsM.
Intestinal Iron Homeostasis and Colon Tumorigenesis

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Yatrik M. Shah

2013-06-01

Full Text Available Colorectal cancer (CRC is the third most common cause of cancer-related deaths in industrialized countries. Understanding the mechanisms of growth and progression of CRC is essential to improve treatment. Iron is an essential nutrient for cell growth. Iron overload caused by hereditary mutations or excess dietary iron uptake has been identified as a risk factor for CRC. Intestinal iron is tightly controlled by iron transporters that are responsible for iron uptake, distribution, and export. Dysregulation of intestinal iron transporters are observed in CRC and lead to iron accumulation in tumors. Intratumoral iron results in oxidative stress, lipid peroxidation, protein modification and DNA damage with consequent promotion of oncogene activation. In addition, excess iron in intestinal tumors may lead to increase in tumor-elicited inflammation and tumor growth. Limiting intratumoral iron through specifically chelating excess intestinal iron or modulating activities of iron transporter may be an attractive therapeutic target for CRC.
Iron metabolism in experimental rickets. I. Intestinal absorption of iron in rat rickets

Energy Technology Data Exchange (ETDEWEB)

Pronicka, E [Pomorska Akademia Medyczna, Szczecin (Poland)

1975-01-01

Investigations were carried out on iron /sup 59/Fe absorption in rats with experimental rickets. It was found that rats with rickets as compared with controls do not show any significant differences in the degree of iron absorption in fasting state. The percent of absorbed iron increases when it is administered after previous feeding of rats. A greater rise in iron absorption after feeding was shown also by rats with rickets. On the other hand, administration of a shock dose of vitamin D at the time of rickets development causes after 7 days a significant decrease in total iron absorption given to fed rats. An excess of calcium in the diet of rats does not seem to impair directly the absorption of iron. The possibility of the causative effect of vitamin D deficiency on the composition of intestinal contents on changes in the degree of iron absorption observed after feeding of rats with rickets, is discussed.
Banded Iron Formations

DEFF Research Database (Denmark)

Posth, Nicole R; Konhauser, Kurt O; Kappler, Andreas

2011-01-01

Sedimentary deposits of alternating iron-rich (20–40% Fe) and iron-poor, siliceous (40–50% SiO2) mineral layers that primarily precipitated throughout much of the late Archean (2.7–2.5 Ga) and Paleoproterozoic (2.5– 1.8 Ga), but then remerged in the Neoproterozoic (0.8 Ga).......Sedimentary deposits of alternating iron-rich (20–40% Fe) and iron-poor, siliceous (40–50% SiO2) mineral layers that primarily precipitated throughout much of the late Archean (2.7–2.5 Ga) and Paleoproterozoic (2.5– 1.8 Ga), but then remerged in the Neoproterozoic (0.8 Ga)....
Daily versus weekly iron supplementation and prevention of iron ...

African Journals Online (AJOL)

Objective: To demonstrate the effectiveness and social feasibility of weekly versus daily iron supplementation in preventing and treating iron deficiency anaemia among anaemic mothers. Design: A longitudinal in nature. Setting: Seven urban slum communities in Teklehaimanot Wereda, Addis Ababa, Ethiopia. Subjects: ...
Evaluation of Ferric and Ferrous Iron Therapies in Women with Iron Deficiency Anaemia

Science.gov (United States)

Berber, Ilhami; Erkurt, Mehmet Ali; Aydogdu, Ismet; Kuku, Irfan

2014-01-01

Introduction. Different ferric and ferrous iron preparations can be used as oral iron supplements. Our aim was to compare the effects of oral ferric and ferrous iron therapies in women with iron deficiency anaemia. Methods. The present study included 104 women diagnosed with iron deficiency anaemia after evaluation. In the evaluations performed to detect the aetiology underlying the iron deficiency anaemia, it was found and treated. After the detection of the iron deficiency anaemia aetiology and treatment of the underlying aetiology, the ferric group consisted of 30 patients treated with oral ferric protein succinylate tablets (2 × 40 mg elemental iron/day), and the second group consisted of 34 patients treated with oral ferrous glycine sulphate tablets (2 × 40 mg elemental iron/day) for three months. In all patients, the following laboratory evaluations were performed before beginning treatment and after treatment. Results. The mean haemoglobin and haematocrit increases were 0.95 g/dL and 2.62% in the ferric group, while they were 2.25 g/dL and 5.91% in the ferrous group, respectively. A significant difference was found between the groups regarding the increase in haemoglobin and haematocrit values (P < 0.05). Conclusion. Data are submitted on the good tolerability, higher efficacy, and lower cost of the ferrous preparation used in our study. PMID:25006339
Electron Spectroscopy Studies of Iron, Iron Sulfides and Supported Iron Surfaces: Chemisorption of Simple Gases.

Science.gov (United States)

Lee, Yiu Chung

EELS was used to investigate the chemisorption of oxygen and carbon on iron. The EELS spectra of oxidized iron show characteristic features with strong enhancement of the interband transitions involving the Fe 3d band (4.6 and 7.5 eV) and moderate enhancement of the M(,2,3) transition doublet (54.4 and 58.2 eV). The changes in the electron energy loss structures with an overlayer of graphitic or carbidic carbon were investigated. The adsorption and growth of iron on Ni(100) has been studied using the combined techniques of LEED and EELS. Initially iron grows by a layer-by-layer mechanism for the first few layers. High iron coverages result in the observation of complex LEED patterns with satellites around the main (1 x 1) diffraction sports. This is due to the formation of b.c.c. Fe(110) crystallites arranged in domains with different orientations. EELS studies show the presence of three stages in the growth of iron on Ni(100): low-coverage, film-like and bulk-like. Auger and EELS were used to study the iron sulfide (FeS(,2), Fe(,7)S(,8) and FeS) surfaces. A characteristic M(,2,3) VV Auger doublet with a separation of 5.0 eV was observed on the sulfides. An assignment of the electron energy loss peaks was made based on the energy dependence of the loss peaks and previous photoemission results. The effect of argon ion bombardment was studied. Peaks with strong iron and sulfur character were observed. Heating the damaged sulfides results in reconstruction of the sulfide surfaces. The reactions of the sulfides with simple gases, such as H(,2), CO, CH(,4), C(,2)H(,4), NH(,3) and O(,2) were also studied. Using XPS, the chemisorption of SO(,2) on CaO(100) has been studied. The chemical state of sulfur has been identified as that of sulfate. The kinetics of SO(,2) chemisorption on CaO are discussed. The binding states of Fe and Na on CaO were determined to be Fe('2+) and Na('+) respectively. At low Fe or Na coverages (< 0.5 ML), there is a large increase in the rate of
Iron, Oxidative Stress and Gestational Diabetes

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Taifeng Zhuang

2014-09-01

Full Text Available Both iron deficiency and hyperglycemia are highly prevalent globally for pregnant women. Iron supplementation is recommended during pregnancy to control iron deficiency. The purposes of the review are to assess the oxidative effects of iron supplementation and the potential relationship between iron nutrition and gestational diabetes. High doses of iron (~relative to 60 mg or more daily for adult humans can induce lipid peroxidation in vitro and in animal studies. Pharmaceutical doses of iron supplements (e.g., 10× RDA or more for oral supplements or direct iron supplementation via injection or addition to the cell culture medium for a short or long duration will induce DNA damage. Higher heme-iron intake or iron status measured by various biomarkers, especially serum ferritin, might contribute to greater risk of gestational diabetes, which may be mediated by iron oxidative stress though lipid oxidation and/or DNA damage. However, information is lacking about the effect of low dose iron supplementation (≤60 mg daily on lipid peroxidation, DNA damage and gestational diabetes. Randomized trials of low-dose iron supplementation (≤60 mg daily for pregnant women are warranted to test the relationship between iron oxidative stress and insulin resistance/gestational diabetes, especially for iron-replete women.
The effects of metamorphism on iron mineralogy and the iron speciation redox proxy

Science.gov (United States)

Slotznick, Sarah P.; Eiler, John M.; Fischer, Woodward W.

2018-03-01

As the most abundant transition metal in the Earth's crust, iron is a key player in the planetary redox budget. Observations of iron minerals in the sedimentary record have been used to describe atmospheric and aqueous redox environments over the evolution of our planet; the most common method applied is iron speciation, a geochemical sequential extraction method in which proportions of different iron minerals are compared to calibrations from modern sediments to determine water-column redox state. Less is known about how this proxy records information through post-depositional processes, including diagenesis and metamorphism. To get insight into this, we examined how the iron mineral groups/pools (silicates, oxides, sulfides, etc.) and paleoredox proxy interpretations can be affected by known metamorphic processes. Well-known metamorphic reactions occurring in sub-chlorite to kyanite rocks are able to move iron between different iron pools along a range of proxy vectors, potentially affecting paleoredox results. To quantify the effect strength of these reactions, we examined mineralogical and geochemical data from two classic localities where Silurian-Devonian shales, sandstones, and carbonates deposited in a marine sedimentary basin with oxygenated seawater (based on global and local biological constraints) have been regionally metamorphosed from lower-greenschist facies to granulite facies: Waits River and Gile Mountain Formations, Vermont, USA and the Waterville and Sangerville-Vassalboro Formations, Maine, USA. Plotting iron speciation ratios determined for samples from these localities revealed apparent paleoredox conditions of the depositional water column spanning the entire range from oxic to ferruginous (anoxic) to euxinic (anoxic and sulfidic). Pyrrhotite formation in samples highlighted problems within the proxy as iron pool assignment required assumptions about metamorphic reactions and pyrrhotite's identification depended on the extraction techniques

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