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Sample records for 316l uns s31603

  1. Dissimilar Friction Stir Welding Between UNS S31603 Austenitic Stainless Steel and UNS S32750 Superduplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Theodoro, Maria Claudia; Pereira, Victor Ferrinho; Mei, Paulo Roberto; Ramirez, Antonio Jose

    2015-02-01

    In order to verify the viability of dissimilar UNS S31603 austenitic and UNS S32750 superduplex stainless steels joined by friction stir welding, 6-mm-thick plates were welded using a PCBN-WRe tool. The welded joints were performed in position control mode at rotational speeds of 100 to 300 rpm and a feed rate of 100 mm/min. The joints performed with 150 and 200 rpm showed good appearance and no defects. The metallographic analysis of both joints showed no internal defects and that the material flow pattern is visible only in the stirred zone (SZ) of the superduplex steel. On the SZ top, these patterns are made of regions of different phases (ferrite and austenite), and on the bottom and central part of the SZ, these patterns are formed by alternated regions of different grain sizes. The ferrite grains in the superduplex steel are larger than those in the austenitic ones along the SZ and thermo-mechanically affected zone, explained by the difference between austenite and ferrite recrystallization kinetics. The amount of ferrite islands present on the austenitic steel base metal decreased near the SZ interface, caused by the dissolving of the ferrite in austenitic matrix. No other phases were found in both joints. The best weld parameters were found to be 200 rpm rotation speed, 100 mm/min feed rate, and tool position control.

  2. Effect of exposure time on corrosion resistance of prepassivated UNS S31603 SS in the Gulf of Mexico

    SciTech Connect

    Acuiia, N.; Herniindet-Duque, G.

    1998-12-31

    The effect of exposure time, in the Gulf of Mexico, on the UNS S3 1603 stainless steel (SS) pitting corrosion resistance (PCR), was studied for 30 days using both open circuit potential (OCP) and potentiodynamic polarization (PP) techniques. Biofilm formation and corrosion attack were subsequently observed using scanning electron microscope (SEM) and atomic force microscopy (AFM). It was found that microorganisms colonizing the steel specimen`s surface during the first three days of testing, modified the OCP towards electropositive values, increasing the risk of pitting corrosion. It was also observed, that the SS specimens were most sensitive to pitting corrosion within the first fifteen days of exposure in seawater, decreasing this sensitivity during the last week, probably due to a decay in the biological activity and better behavior of the passive film.

  3. Fabrication of antibacterial and hydrophilic electroless Ni-B coating on 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Bülbül, Ferhat; Bülbül, Leman Elif

    2016-01-01

    Biomaterial-associated bacterial infection is one of the most common complications with medical vehicles and implants made of stainless steel. A surface coating treatment like electroless Ni-B deposition, a new candidate to be used in a broad range of engineering applications owing to many advantages such as low cost, thickness uniformity, good wear resistance, may improve the antibacterial activity and physical properties of biomedical devices made of stainless steel. In this study, the antibacterial property of the electroless Ni-B film coated on AISI 316L (UNS S31603) stainless steel is basically investigated. Inhibition halo diameter measurement after incubation at 37 °C and 24 h demonstrates the existence of antimicrobial activity of the electroless Ni-B coating deposited on 316L stainless steel over the Escherichia coli test bacteria. The results of X-ray diffraction, scanning electron microscopy, atomic force microscopy and microhardness measurement studies confirms that the coating deposited on the substrate has an uniform amorphous and a harder structure. Besides, the wettability property of the uncoated substrate and the coating was measured as the contact angle of water. The water contact angle reduced about from 97.7 to 69.25°.

  4. Electron Backscatter Diffraction Analysis of Joints Between AISI 316L Austenitic/UNS S32750 Dual-Phase Stainless Steel

    NASA Astrophysics Data System (ADS)

    Shamanian, Morteza; Mohammadnezhad, Mahyar; Amini, Mahdi; Zabolian, Azam; Szpunar, Jerzy A.

    2015-08-01

    Stainless steels are among the most economical and highly practicable materials widely used in industrial areas due to their mechanical and corrosion resistances. In this study, a dissimilar weld joint consisting of an AISI 316L austenitic stainless steel (ASS) and a UNS S32750 dual-phase stainless steel was obtained under optimized welding conditions by gas tungsten arc welding technique using AWS A5.4:ER2594 filler metal. The effect of welding on the evolution of the microstructure, crystallographic texture, and micro-hardness distribution was also studied. The weld metal (WM) was found to be dual-phased; the microstructure is obtained by a fully ferritic solidification mode followed by austenite precipitation at both ferrite boundaries and ferrite grains through solid-state transformation. It is found that welding process can affect the ferrite content and grain growth phenomenon. The strong textures were found in the base metals for both steels. The AISI 316L ASS texture is composed of strong cube component. In the UNS S32750 dual-phase stainless steel, an important difference between the two phases can be seen in the texture evolution. Austenite phase is composed of a major cube component, whereas the ferrite texture mainly contains a major rotated cube component. The texture of the ferrite is stronger than that of austenite. In the WM, Kurdjumov-Sachs crystallographic orientation relationship is found in the solidification microstructure. The analysis of the Kernel average misorientation distribution shows that the residual strain is more concentrated in the austenite phase than in the other phase. The welding resulted in a significant hardness increase in the WM compared to initial ASS.

  5. Re-weldability tests of irradiated 316L(N) stainless steel using laser welding technique

    NASA Astrophysics Data System (ADS)

    Yamada, Hirokazu; Kawamura, Hiroshi; Tsuchiya, Kunihiko; Kalinin, George; Kohno, Wataru; Morishima, Yasuo

    2002-12-01

    SS316L(N)-IG is the candidate material for the in-vessel and ex-vessel components of fusion reactors such as ITER (International Thermonuclear Experimental Reactor). This paper describes a study on re-weldability of un-irradiated and/or irradiated SS316L(N)-IG and the effect of helium generation on the mechanical properties of the weld joint. The laser welding process is used for re-welding of the water cooling branch pipeline repairs. It is clarified that re-welding of SS316L(N)-IG irradiated up to about 0.2 dpa (3.3 appm He) can be carried out without a serious deterioration of tensile properties due to helium accumulation. Therefore, repair of the ITER blanket cooling pipes can be performed by the laser welding process.

  6. Étude expérimentale du comportement cyclique d'un acier du type 316 L sous chargement multiaxial complexe en traction-torsion-pressions interne et externe

    NASA Astrophysics Data System (ADS)

    Bocher, L.; Delobelle, P.

    1997-09-01

    This paper is concerned with the experimental determination of the behaviour of a 316 L austenitic stainless steel at room temperature and under non proportional cyclic strainings in tension-torsion- internal and external pressures. The two or three sinusoïdal strains were applied both in and out-of-phase and the main investigations deal with the additional hardening due to multiaxiality of the loadings. Typical stabilized hysteresis loops are presented. With respect to the maximum additional hardening the different tests can be classified as follows : in phase tests, out-of-phase internal-external pressures tests, out-of-phase tension-torsion tests and finally tension-torsion-pressure with significant phase angles A device is presented which allows cyclic tests to be performed on tubes for loadings in tension-torsion-internal and external pressures. It is composed of a medium pressure chamber enclosing the gage length of the test specimen, directly fixed on the specimen and connected to two pressure regulators. The specimen is also fastened to the jaws of a hydraulic tensile-torsion machine through two extension rods. The entire device is controlled with the help of strain gauges set directly on the gage zone of the test specimen. Different tests have been performed at ambient temperature on an austenitic stainless steel which has the particularity of presenting a strong supplementary hardening connected to the non-radiality of the loadings. The influence of the phase shift parameters, namely the angles δ and \\varphi (δ: tension-torsion, \\varphi: tension-pressures) for two or three cyclic sinusoïdal components and for a total equivalent strain amplitude level imposed at 0.4% was studied. The ratios of the maximum strain amplitudes were respectively fixed at r_2 = 1 and r_1 = ± 1 (r_2: tension-torsion and r_1: tension-pressures). These tests allowed both the hypotheses made in stress calculations and the whole of the experimental set up to be validated. They

  7. Surface modification of investment cast-316L implants: microstructure effects.

    PubMed

    El-Hadad, Shimaa; Khalifa, Waleed; Nofal, Adel

    2015-03-01

    Artificial femur stem of 316L stainless steel was fabricated by investment casting using vacuum induction melting. Different surface treatments: mechanical polishing, thermal oxidation and immersion in alkaline solution were applied. Thicker hydroxyapatite (HAP) layer was formed in the furnace-oxidized samples as compared to the mechanically polished ones. The alkaline treatment enhanced the precipitation of HAP on the samples. It was also observed that the HAP precipitation responded differently to the different phases of the microstructure. The austenite phase was observed to have more homogeneous and smoother layer of HAP. In addition, the growth of HAP was sometimes favored on the austenite phase rather than on ferrite phase.

  8. Corrosion protection performance of porous strontium hydroxyapatite coating on polypyrrole coated 316L stainless steel.

    PubMed

    Gopi, D; Ramya, S; Rajeswari, D; Kavitha, L

    2013-07-01

    Polypyrrole/strontium hydroxyapatite bilayer coatings were achieved on 316L stainless steel (316L SS) by the electropolymerisation of pyrrole from sodium salicylate solution followed by the electrodeposition of porous strontium hydroxyapatite. The formation and the morphology of the bilayer coatings were characterised by Fourier transform infrared spectroscopy (FT-IR) and high resolution scanning electron microscopy (HRSEM), respectively. The corrosion resistance of the coated 316L SS specimens was investigated in Ringer's solution by electrochemical techniques and the results were substantiated with inductively coupled plasma atomic emission spectrometry (ICP-AES). The passive film underneath the polypyrrole layer is effective in protecting 316L SS against corrosion in Ringer's solution. Moreover, we believe that the top porous strontium hydroxyapatite layer can provide potential bioactivity to the 316L SS.

  9. Corrosion protection performance of porous strontium hydroxyapatite coating on polypyrrole coated 316L stainless steel.

    PubMed

    Gopi, D; Ramya, S; Rajeswari, D; Kavitha, L

    2013-07-01

    Polypyrrole/strontium hydroxyapatite bilayer coatings were achieved on 316L stainless steel (316L SS) by the electropolymerisation of pyrrole from sodium salicylate solution followed by the electrodeposition of porous strontium hydroxyapatite. The formation and the morphology of the bilayer coatings were characterised by Fourier transform infrared spectroscopy (FT-IR) and high resolution scanning electron microscopy (HRSEM), respectively. The corrosion resistance of the coated 316L SS specimens was investigated in Ringer's solution by electrochemical techniques and the results were substantiated with inductively coupled plasma atomic emission spectrometry (ICP-AES). The passive film underneath the polypyrrole layer is effective in protecting 316L SS against corrosion in Ringer's solution. Moreover, we believe that the top porous strontium hydroxyapatite layer can provide potential bioactivity to the 316L SS. PMID:23475060

  10. Intragranular cellular segregation network structure strengthening 316L stainless steel prepared by selective laser melting

    NASA Astrophysics Data System (ADS)

    Zhong, Yuan; Liu, Leifeng; Wikman, Stefan; Cui, Daqing; Shen, Zhijian

    2016-03-01

    A feasibility study was performed to fabricate ITER In-Vessel components by Selective Laser Melting (SLM) supported by Fusion for Energy (F4E). Almost fully dense 316L stainless steel (SS316L) components were prepared from gas-atomized powder and with optimized SLM processing parameters. Tensile tests and Charpy-V tests were carried out at 22 °C and 250 °C and the results showed that SLM SS316L fulfill the RCC-MR code. Microstructure characterization reveals the presence of hierarchical macro-, micro- and nano-structures in as-built samples that were very different from SS316L microstructures prepared by other established methods. The formation of a characteristic intragranular cellular segregation network microstructure appears to contribute to the increase of yield strength without losing ductility. Silicon oxide nano-inclusions were formed during the SLM process that generated a micro-hardness fluctuation in the building direction. The combined influence of a cellular microstructure and the nano-inclusions constraints the size of ductile dimples to nano-scale. The crack propagation is hindered by a pinning effect that improves the defect-tolerance of the SLM SS316L. This work proves that it was possible to manufacture SS316L with properties suitable for ITER First Wall panels. Further studies on irradiation properties of SLM SS316L and manufacturing of larger real-size components are needed.

  11. Electrochemical properties of 316L stainless steel with culturing L929 fibroblasts

    PubMed Central

    Hiromoto, Sachiko; Hanawa, Takao

    2005-01-01

    Potentiodynamic polarization and impedance tests were carried out on 316L stainless steel with culturing murine fibroblast L929 cells to elucidate the corrosion behaviour of 316L steel with L929 cells and to understand the electrochemical interface between 316L steel and cells, respectively. Potential step test was carried out on 316L steel with type I collagen coating and culturing L929 cells to compare the effects of collagen and L929 cells. The open-circuit potential of 316L steel slightly shifted in a negative manner and passive current density increased with cells, indicating a decrease in the protective ability of passive oxide film. The pitting potential decreased with cells, indicating a decrease in the pitting corrosion resistance. In addition, a decrease in diffusivity at the interface was indicated from the decrease in the cathodic current density and the increase in the diffusion resistance parameter in the impedance test. The anodic peak current in the potential step test decreased with cells and collagen. Consequently, the corrosion resistance of 316L steel decreases with L929 cells. In addition, collagen coating would provide an environment for anodic reaction similar to that with culturing cells. PMID:16849246

  12. Effect of the La alloying addition on the antibacterial capability of 316L stainless steel.

    PubMed

    Yuan, J P; Li, W; Wang, C

    2013-01-01

    316L stainless steel is widely used for fashion jewelry but it can carry a large number of bacteria and cause the potential risk of infection since it has no antimicrobial ability. In this paper, La is used as an alloying addition. The antibacterial capability, corrosion resistance and processability of the La-modified 316L are investigated by microscopic observation, thin-film adhering quantitative bacteriostasis, electrochemical measurement and mechanical test. The investigations reveal that the La-containing 316L exhibits the Hormesis effect against Staphylococcus aureus ATCC 25923 and Escherichia coli DH5α, 0.05 wt.% La stimulates their growth, as La increases, the modified 316L exhibits the improved antibacterial effect. The more amount of La is added, the better antibacterial ability is achieved, and 0.42 wt.% La shows excellent antibacterial efficacy. No more than 0.11 wt.% La addition improves slightly the corrosion resistance in artificial sweat and has no observable impact on the processability of 316L, while a larger La content degrades them. Therefore, the addition of La alone in 316L is difficult to obtain the optimal combination of corrosion resistance, antibacterial capability and processability. In spite of that, 0.15 wt.% La around is inferred to be the trade-off for the best overall performance.

  13. Highly porous, low elastic modulus 316L stainless steel scaffold prepared by selective laser melting.

    PubMed

    Čapek, Jaroslav; Machová, Markéta; Fousová, Michaela; Kubásek, Jiří; Vojtěch, Dalibor; Fojt, Jaroslav; Jablonská, Eva; Lipov, Jan; Ruml, Tomáš

    2016-12-01

    Recently, porous metallic materials have been extensively studied as candidates for use in the fabrication of scaffolds and augmentations to repair trabecular bone defects, e.g. in surroundings of joint replacements. Fabricating these complex structures by using common approaches (e.g., casting and machining) is very challenging. Therefore, rapid prototyping techniques, such as selective laser melting (SLM), have been investigated for these applications. In this study, we characterized a highly porous (87 vol.%) 316L stainless steel scaffold prepared by SLM. 316L steel was chosen because it presents a biomaterial still widely used for fabrication of joint replacements and, from the practical point of view, use of the same material for fabrication of an augmentation and a joint replacement is beneficial for corrosion prevention. The results are compared to the reported properties of two representative nonporous 316L stainless steels prepared either by SLM or casting and subsequent hot forging. The microstructural and mechanical properties and the surface chemical composition and interaction with the cells were investigated. The studied material exhibited mechanical properties that were similar to those of trabecular bone (compressive modulus of elasticity ~0.15GPa, compressive yield strength ~3MPa) and cytocompatibility after one day that was similar to that of wrought 316L stainless steel, which is a commonly used biomaterial. Based on the obtained results, SLM is a suitable method for the fabrication of porous 316L stainless steel scaffolds with highly porous structures.

  14. Highly porous, low elastic modulus 316L stainless steel scaffold prepared by selective laser melting.

    PubMed

    Čapek, Jaroslav; Machová, Markéta; Fousová, Michaela; Kubásek, Jiří; Vojtěch, Dalibor; Fojt, Jaroslav; Jablonská, Eva; Lipov, Jan; Ruml, Tomáš

    2016-12-01

    Recently, porous metallic materials have been extensively studied as candidates for use in the fabrication of scaffolds and augmentations to repair trabecular bone defects, e.g. in surroundings of joint replacements. Fabricating these complex structures by using common approaches (e.g., casting and machining) is very challenging. Therefore, rapid prototyping techniques, such as selective laser melting (SLM), have been investigated for these applications. In this study, we characterized a highly porous (87 vol.%) 316L stainless steel scaffold prepared by SLM. 316L steel was chosen because it presents a biomaterial still widely used for fabrication of joint replacements and, from the practical point of view, use of the same material for fabrication of an augmentation and a joint replacement is beneficial for corrosion prevention. The results are compared to the reported properties of two representative nonporous 316L stainless steels prepared either by SLM or casting and subsequent hot forging. The microstructural and mechanical properties and the surface chemical composition and interaction with the cells were investigated. The studied material exhibited mechanical properties that were similar to those of trabecular bone (compressive modulus of elasticity ~0.15GPa, compressive yield strength ~3MPa) and cytocompatibility after one day that was similar to that of wrought 316L stainless steel, which is a commonly used biomaterial. Based on the obtained results, SLM is a suitable method for the fabrication of porous 316L stainless steel scaffolds with highly porous structures. PMID:27612756

  15. Laser surface modification of 316 L stainless steel with bioactive hydroxyapatite.

    PubMed

    Balla, Vamsi Krishna; Das, Mitun; Bose, Sreyashree; Ram, G D Janaki; Manna, Indranil

    2013-12-01

    Laser-engineered net shaping (LENS™), a commercial additive manufacturing process, was used to modify the surfaces of 316 L stainless steel with bioactive hydroxyapatite (HAP). The modified surfaces were characterized in terms of their microstructure, hardness and apatite forming ability. The results showed that with increase in laser energy input from 32 J/mm(2) to 59 J/mm(2) the thickness of the modified surface increased from 222±12 μm to 355±6 μm, while the average surface hardness decreased marginally from 403±18 HV0.3 to 372±8 HV0.3. Microstructural studies showed that the modified surface consisted of austenite dendrites with HAP and some reaction products primarily occurring in the inter-dendritic regions. Finally, the surface-modified 316 L samples immersed in simulated body fluids showed significantly higher apatite precipitation compared to unmodified 316 L samples.

  16. Resistance of superhydrophobic and oleophobic surfaces to varied temperature applications on 316L SS

    NASA Astrophysics Data System (ADS)

    Shams, Hamza; Basit, Kanza; Saleem, Sajid; Siddiqui, Bilal A.

    316L SS also called Marine Stainless Steel is an important material for structural and marine applications. When superhydrophobic and oleophobic coatings are applied on 316L SS it shows significant resistance to wear and corrosion. This paper aims to validate the coatings manufacturer's information on optimal temperature range and test the viability of coating against multiple oil based cleaning agents. 316L SS was coated with multiple superhydrophic and oleohobic coatings and observed under SEM for validity of adhesion and thickness and then scanned under FFM to validate the tribological information. The samples were then dipped into multiple cleaning agents maintained at the range of operating temperatures specified by the manufacturer. Coating was observed for deterioration over a fixed time intervals through SEM and FFM. A comparison was drawn to validate the most critical cleaning agent and the most critical temperature at which the coating fails to leave the base substrate exposed to the environment.

  17. An evaluation of microbial growth and corrosion of 316L SS in glycol/seawater mixtures

    NASA Technical Reports Server (NTRS)

    Lee, Jason S.; Ray, Richard I.; Lowe, Kristine L.; Jones-Meehan, Joanne; Little, Brenda J.

    2003-01-01

    Glycol/seawater mixtures containing > 50% glycol inhibit corrosion of 316L stainless steel and do not support bacterial growth. The results indicate bacteria are able to use low concentrations of glycol (10%) as a growth medium, but bacterial growth decreased with increasing glycol concentration. Pitting potential, determined by anodic polarization, was used to evaluate susceptibility of 316L SS to corrosion in seawater-contaminated glycol. Mixture containing a minimum concentration of 50% propylene glycol-based coolant inhibited pitting corrosion. A slightly higher minimum concentration (55%) was needed for corrosion protection in ethylene glycol mixtures.

  18. Development of nanostructured SUS316L-2%TiC with superior tensile properties

    NASA Astrophysics Data System (ADS)

    Sakamoto, T.; Kurishita, H.; Matsuo, S.; Arakawa, H.; Takahashi, S.; Tsuchida, M.; Kobayashi, S.; Nakai, K.; Terasawa, M.; Yamasaki, T.; Kawai, M.

    2015-11-01

    Structural materials used in radiation environments require radiation tolerance and sufficient mechanical properties in the controlled state. In order to offer SUS316L austenitic stainless steel with the assumed requirements, nanostructured SUS316L with TiC addition of 2% (SUS316L-2TiC) that is capable of exhibiting enhanced tensile ductility and flow strength sufficient for structural applications was fabricated by advanced powder metallurgical methods. The methods include MA (Mechanical Alloying), HIP (Hot Isostatic Pressing), GSMM (Grain boundary Sliding Microstructural Modification) for ductility enhancement, cold rolling at temperatures below Md (the temperature where the martensite phase occurs by plastic deformation) for phase transformation from austenite to martensite and heat treatment for reverse transformation from martensite to austenite. It is shown that the developed SUS316L-2TiC exhibits ultrafine grains with sizes of 90-270 nm, accompanied by TiC precipitates with 20-50 nm in grain interior and 70-110 nm at grain boundaries, yield strengths of 1850 to 900 MPa, tensile strengths of 1920 to 1100 MPa and uniform elongations of 0.6-21%, respectively, depending on the heat treatment temperature after rolling at -196 °C.

  19. Microstructure and Corrosion Resistance of Laser Additively Manufactured 316L Stainless Steel

    NASA Astrophysics Data System (ADS)

    Trelewicz, Jason R.; Halada, Gary P.; Donaldson, Olivia K.; Manogharan, Guha

    2016-03-01

    Additive manufacturing (AM) of metal alloys to produce complex part designs via powder bed fusion methods such as laser melting promises to be a transformative technology for advanced materials processing. However, effective implementation of AM processes requires a clear understanding of the processing-structure-properties-performance relationships in fabricated components. In this study, we report on the formation of micro and nanoscale structures in 316L stainless steel samples printed by laser AM and their implications for general corrosion resistance. A variety of techniques including x-ray diffraction, optical, scanning and transmission electron microscopy, x-ray fluorescence, and energy dispersive x-ray spectroscopy were employed to characterize the microstructure and chemistry of the laser additively manufactured 316L stainless steel, which are compared with wrought 316L coupons via electrochemical polarization. Apparent segregation of Mo has been found to contribute to a loss of passivity and an increased anodic current density. While porosity will also likely impact the environmental performance (e.g., facilitating crevice corrosion) of AM alloys, this work demonstrates the critical influence of microstructure and heterogeneous solute distributions on the corrosion resistance of laser additively manufactured 316L stainless steel.

  20. Corrosive Metabolic Activity of Desulfovibrio sp. on 316L Stainless Steel

    NASA Astrophysics Data System (ADS)

    Arkan, Simge; Ilhan-Sungur, Esra; Cansever, Nurhan

    2016-10-01

    The present study investigated the effects of chemical parameters (SO4 2-, PO4 3-, Cl-, pH) and the contents of extracellular polymeric substances (EPS) regarding the growth of Desulfovibrio sp. on the microbiologically induced corrosion of 316L stainless steel (SS). The experiments were carried out in laboratory-scaled test and control systems. 316L SS coupons were exposed to Desulfovibrio sp. culture over 720 h. The test coupons were removed at specific sampling times for enumeration of Desulfovibrio sp., determination of the corrosion rate by the weight loss measurement method and also for analysis of carbohydrate and protein in the EPS. The chemical parameters of the culture were also established. Biofilm/film formation and corrosion products on the 316L SS surfaces were investigated by scanning electron microscopy and energy-dispersive x-ray spectrometry analyses in the laboratory-scaled systems. It was found that Desulfovibrio sp. led to the corrosion of 316L SS. Both the amount of extracellular protein and chemical parameters (SO4 2- and PO4 3-) of the culture caused an increase in the corrosion of metal. There was a significantly positive relationship between the sessile and planktonic Desulfovibrio sp. counts (p < 0.01). It was detected that the growth phases of the sessile and planktonic Desulfovibrio sp. were different from each other and the growth phases of the sessile Desulfovibrio sp. vary depending on the subspecies of Desulfovibrio sp. and the type of metal when compared with the other published studies.

  1. Structure and Long-Term Stability of Alkylphosphonic Acid Monolayers on SS316L Stainless Steel.

    PubMed

    Kosian, Medea; Smulders, Maarten M J; Zuilhof, Han

    2016-02-01

    Surface modification of stainless steel (SS316L) to improve surface properties or durability is an important avenue of research, as SS316L is widely used in industry and science. We studied, therefore, the formation and stability of a series of organic monolayers on SS316L under industrially relevant conditions. These included acidic (pH 3), basic (pH 11), neutral (Milli-Q water), and physiological conditions [10 mM phosphate-buffered saline (PBS)], as well as dry heating (120 °C). SS316L was modified with alkylphosphonic acids of chain length (CH2)n with n varying between 3 and 18. While alkylphosphonic acids of all chain lengths formed self-assembled monolayers with hydrophobic properties, only monolayers of chain lengths 12-18 formed ordered monolayers, as evidenced by static water contact angle (SCA), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and infrared reflection absorption spectroscopy (IRRAS). A long-term stability study revealed the excellent stability of monolayers with chain lengths 12-18 for up to 30 days in acid, neutral, and physiological solutions, and for up to 7 days under dry heating. Under strong basic conditions a partial breakdown of the monolayer was observed, especially for the shorter chain lengths. Finally, the effect of multivalent surface attachment on monolayer stability was explored by means of a series of divalent bisphosphonic acids. PMID:26771302

  2. [Corrosion of stainless steel 201, 304 and 316L in the simulated sewage pipes reactor].

    PubMed

    Bao, Guo-Dong; Zuo, Jian-E; Wang, Ya-Jiao; Gan, Li-Li

    2014-08-01

    The corrosion behavior of stainless steel 201, 304 and 316L which would be used as sewer in-situ rehabilitation materials was studied in the simulated sewage pipes reactor. The corrosion potential and corrosion rate of these three materials were studied by potentiodynamic method on the 7th, 14th, 21st, 56th day under two different conditions which were full immersion condition or batch immersion condition with a 2-day cycle. The electrode process was studied by Electrochemical Impedance Spectroscopy (EIS) on the 56th day. The microstructure and composition of the corrosion pitting were analyzed by Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) on the 56th day. The results showed that 304 and 316L had much better corrosion resistance than 201 under both conditions. 304 and 316L had much smaller corrosion rate than 201 under both conditions. The corrosion resistance of all three kinds of stainless steel under the batch immersion condition was much better than those under the full immersion condition. The corrosion rate of all three kinds of stainless steel under the batch immersion condition was much smaller than those under the full immersion condition. Point pitting corrosion was formed on the surfaces of 304 and 316L. In comparison, a large area of corrosion was formed in the surface of 201.

  3. Hydrothermal calcium modification of 316L stainless steel and its apatite forming ability in simulated body fluid.

    PubMed

    Valanezahad, Alireza; Ishikawa, Kunio; Tsuru, Kanji; Maruta, Michito; Matsuya, Shigeki

    2011-01-01

    To understand the feasibility of calcium (Ca) modification of type 316L stainless steel (316L SS) surface using hydrothermal treatment, 316L SS plates were treated hydrothermally in calcium chloride (CaCl(2)) solution. X-ray photoelectron spectroscopic analysis revealed that the surface of 316L SS plate was modified with Ca after hydrothermal treatment at 200°C. And the immobilized Ca increased with CaCl(2) concentration. However no Ca-modification was occurred for 316L SS plates treated at 100°C. When Ca-modified 316L SS plate was immersed in simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma, low crystalline apatite was precipitated on its surface whereas no precipitate was observed on non Ca-modified 316L SS. The results obtained in the present study indicated that hydrothermal treatment at 200°C in CaCl(2) solution is useful for Ca-modification of 316L SS, and Ca-modification plays important role for apatite precipitation in SBF.

  4. In vitro biocompatibility of plasma-aided surface-modified 316L stainless steel for intracoronary stents.

    PubMed

    Bayram, Cem; Mizrak, Alpay Koray; Aktürk, Selçuk; Kurşaklioğlu, Hurkan; Iyisoy, Atila; Ifran, Ahmet; Denkbaş, Emir Baki

    2010-10-01

    316L-type stainless steel is a raw material mostly used for manufacturing metallic coronary stents. The purpose of this study was to examine the chemical, wettability, cytotoxic and haemocompatibility properties of 316L stainless steel stents which were modified by plasma polymerization. Six different polymeric compounds, polyethylene glycol, 2-hydroxyethyl methacrylate, ethylenediamine, acrylic acid, hexamethyldisilane and hexamethyldisiloxane, were used in a radio frequency glow discharge plasma polymerization system. As a model antiproliferative drug, mitomycin-C was chosen for covalent coupling onto the stent surface. Modified SS 316L stents were characterized by water contact angle measurements (goniometer) and x-ray photoelectron spectroscopy. C1s binding energies showed a good correlation with the literature. Haemocompatibility tests of coated SS 316L stents showed significant latency (t-test, p < 0.05) with respect to SS 316L and control groups in each test. PMID:20844318

  5. Pitting corrosion behavior of 316L stainless steels in tropical seawater

    SciTech Connect

    Zaragoza-Ayala, A.E.; Acuna, N.; Solis, W.; Aldana, J.; Festy, D.

    1996-10-01

    The open circuit potential (OCP) and the pitting potential of 316L stainless steel (SS) have been determined as a function of the immersion time in tropical seawater. An increase in the noble direction of the OCP for short exposures was observed. After certain time occasional fall and rise of the OCP values was observed. Pitting potentials measurements shows that a relatively small increase in the seawater temperature can increase the susceptibility to localized corrosion of this alloy. Little or no effect of the exposure time on the pitting potential was observed. SEM observation shows that the steel surface was colonized by bacteria an microalgae which forms an heterogeneous biofilm on the steel surface which probably have an influence on the corrosion behavior of 316 L SS in seawater.

  6. Re-weldability of neutron irradiated Type 304 and 316L stainless steels

    NASA Astrophysics Data System (ADS)

    Morishima, Y.; Koshiishi, M.; Kashiwakura, K.; Hashimoto, T.; Kawano, S.

    2004-08-01

    Weldability of irradiated stainless steel (SS) has been studied to develop the technical guideline regarding the repair-welding of reactor internals. Type 304 and 316L SSs were irradiated at ambient temperature in the US Advanced Test Reactor. The multi-pass bead-on-plate TIG (GTA) and YAG laser welding with heat input levels less than 1 MJ/m were performed on specimens containing helium up to 18 appm. In this paper, results of cross-sectional micrograph observations of the heat affected zone were considered in light of helium bubble properties. The tendency for weld crack formation of irradiated Type 316L SS was compared with that of irradiated Type 304 SS.

  7. Damage mechanism at different transpassive potentials of solution-annealed 316 and 316l stainless steels

    NASA Astrophysics Data System (ADS)

    Morshed Behbahani, K.; Pakshir, M.; Abbasi, Z.; Najafisayar, P.

    2015-01-01

    Electrochemical impedance spectroscopy (EIS), anodic polarization and scanning electron microscopy techniques were used to investigate the damage mechanism in the transpassive potential region of AISI 316 and AISI 316L solution-annealed stainless steels (SS) with different degrees of sensitization. Depending on the DC potential applied during EIS tests, the AC responses in the transpassive region included three different regions: the first one associated with anodic dissolution of the passive layer, the second one contributed to the dissolution at the area near grain boundaries, and the last one attributed to pitting corrosion. In addition, the fitting results to experimental data showed that as the DC bias during the EIS test increases the charge transfer resistance ( R ct) decreases. Moreover, the R ct values decreased as the sensitization temperature increases but the AISI 316L SS samples exhibited a higher resistance to intergranular corrosion than 316 SS samples.

  8. Improving endothelialization on 316L stainless steel through wettability controllable coating by sol-gel technology

    NASA Astrophysics Data System (ADS)

    Wang, Mingqi; Wang, Yao; Chen, Yijie; Gu, Hongchen

    2013-03-01

    Rapid endothelialization by surface coverage is considered as a way to increase blood compatibility of the vascular stent and reduce smooth muscle cell (SMC) mediated restenosis. Coatings on 316L stainless steels with different wettabilities and similar topographies were obtained through sol-gel process by regulating the proportions of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES). Adhesion and proliferation of vascular endothelial cells (EC) and SMC on these substrates have been evaluated by cell numbers, cell morphology, and expression of cytoskeletal protein. Results showed that EC and SMC responded differently to the coated surfaces. Enhanced endothelialization of bare 316L was found at the moderately hydrophilic coating (contact angle 45.3°) which exhibited effective inhibition of SMC and negligible influence on EC. These results are expected to lay foundation for the solution of the vascular restenosis which was mainly derived from the hyperplasia of SMC.

  9. Creep rupture strength of activated-TIG welded 316L(N) stainless steel

    NASA Astrophysics Data System (ADS)

    Sakthivel, T.; Vasudevan, M.; Laha, K.; Parameswaran, P.; Chandravathi, K. S.; Mathew, M. D.; Bhaduri, A. K.

    2011-06-01

    316L(N) stainless steel plates were joined using activated-tungsten inert gas (A-TIG) welding and conventional TIG welding process. Creep rupture behavior of 316L(N) base metal, and weld joints made by A-TIG and conventional TIG welding process were investigated at 923 K over a stress range of 160-280 MPa. Creep test results showed that the enhancement in creep rupture strength of weld joint fabricated by A-TIG welding process over conventional TIG welding process. Both the weld joints fractured in the weld metal. Microstructural observation showed lower δ-ferrite content, alignment of columnar grain with δ-ferrite along applied stress direction and less strength disparity between columnar and equiaxed grains of weld metal in A-TIG joint than in MP-TIG joint. These had been attributed to initiate less creep cavitation in weld metal of A-TIG joint leading to improvement in creep rupture strength.

  10. Effect of Surface Treatment on the Surface Characteristics of AISI 316L Stainless Steel

    NASA Technical Reports Server (NTRS)

    Trigwell, Steve; Selvaduray, Guna

    2005-01-01

    The ability of 316L stainless steel to maintain biocompatibility, which is dependent upon the surface characteristics, is critical to its effectiveness as an implant material. The surfaces of mechanically polished (MP), electropolished (EP) and plasma treated 316L stainless steel coupons were characterized by X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) for chemical composition, Atomic Force Microscopy for surface roughness, and contact angle measurements for critical surface tension. All surfaces had a Ni concentration that was significantly lower than the bulk concentration of -43%. The Cr content of the surface was increased significantly by electropolishing. The surface roughness was also improved significantly by electropolishing. Plasma treatment had the reverse effect - the surface Cr content was decreased. It was also found that the Cr and Fe in the surface exist in both the oxide and hydroxide states, with the ratios varying according to surface treatment.

  11. Microstructure of Au-ion irradiated 316L and FeNiCr austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Jublot-Leclerc, S.; Li, X.; Legras, L.; Lescoat, M.-L.; Fortuna, F.; Gentils, A.

    2016-11-01

    Thin foils of 316L were irradiated in situ in a Transmission Electron Microscope with 4 MeV Au ions at 450 °C and 550 °C. Similar irradiations were performed at 450 °C in FeNiCr. The void and dislocation microstructure of 316L is found to depend strongly on temperature. At 450 °C, a dense network of dislocation lines is observed in situ to grow from black dot defects by absorption of other black dots and interstitial clusters whilst no Frank loops are detected. At 550 °C, no such network is observed but large Frank loops and perfect loops whose sudden appearance is concomitant with a strong increase in void density as a result of a strong coupling between voids and dislocations. Moreover, differences in both alloys microstructure show the major role played by the minor constituents of 316L, increasing the stacking fault formation energy, and possibly leading to significant differences in swelling behaviour.

  12. Laser-driven shock waves to improve the corrosion properties of 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Peyre, Patrice; Berthe, Laurent; Fabbro, Remy; Carboni, Christelle; Bartnicki, Eric; Beranger, Gerard; Lemaitre, Christian

    1999-06-01

    Different laser pulses ranging between 0.6 and 10 ns were used to generate up to 10 GPa amplitude shock waves in an aluminum-coated 316L stainless steel with application to modify its surface behavior, especially its pitting corrosion behavior in NaCl 30g/l medium. Laser shock waves (LSW) characterizations (Hugoniot limits, Shock wave attenuations) were carried out with a VISAR system and compared with 1D simulations using Shylac Lagrangian code. Treated surfaces were analyzed through chemical spectroscopies (GDS, XPS), metallurgical characterizations (deformation bands, twins...) and residual stress measurements. Laser-induced surface modifications were also compared with the classical effects of a shot-peening at high coverage rate. Lastly, rest potential recordings, anodic polarization tests and statistical treatments of the pitting potentials were carried out to estimate the influence of a laser peening on the pitting corrosion resistance of a passive 316L alloy. It was clearly demonstrated that LSW could improve the corrosion behavior of 316L by pure mechanical effects such as compressive residual stresses which tend to reduce the nocivity of surface inclusions.

  13. Investigation on 316L/W functionally graded materials fabricated by mechanical alloying and spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Tan, Chao; Wang, Guoyu; Ji, Lina; Tong, Yangang; Duan, Xuan-Ming

    2016-02-01

    316L-W (Tungsten) composite materials were fabricated by spark plasma sintering (SPS) of mechanically alloyed 316L-W powders for the development of functionally graded materials (FGMs). The effect of milling parameters on the morphology of the blended 316L/W powders and its subsequent effect on the transition between 316L and W particles during the SPS process were investigated. Samples were characterized by SEM, EDS and XRD analyses. The results so obtained show that with the increase of milling time, the mechanically activated W powder particles become thinner and smoother, with some broken fragments aggregated or inserted in the severely deformed 316L particles. A further SPS process under the conditions of 1050 °C × 45.5 MPa × 5 min leads to the densification of the powder compact and the formation of a distinguishable gray belt surrounding the retained W particles. Such a belt, which has a width of about 2-8 μm depending on different milling parameters and mainly contains Fe7W6, Fe3W3C and Fe2W phases, is bound to be a transitional region between the retained W particles and the 316L matrix. This favorable behavior with regards to the formation of a transitional belt, is accompanied by a substantial increase in the hardness values of the composite.

  14. Optimization of Process Parameters of Hybrid Laser-Arc Welding onto 316L Using Ensemble of Metamodels

    NASA Astrophysics Data System (ADS)

    Zhou, Qi; Jiang, Ping; Shao, Xinyu; Gao, Zhongmei; Cao, Longchao; Yue, Chen; Li, Xiongbin

    2016-08-01

    Hybrid laser-arc welding (LAW) provides an effective way to overcome problems commonly encountered during either laser or arc welding such as brittle phase formation, cracking, and porosity. The process parameters of LAW have significant effects on the bead profile and hence the quality of joint. This paper proposes an optimization methodology by combining non-dominated sorting genetic algorithm (NSGA-II) and ensemble of metamodels (EMs) to address multi-objective process parameter optimization in LAW onto 316L. Firstly, Taguchi experimental design is adopted to generate the experimental samples. Secondly, the relationships between process parameters ( i.e., laser power ( P), welding current ( A), distance between laser and arc ( D), and welding speed ( V)) and the bead geometries are fitted using EMs. The comparative results show that the EMs can take advantage of the prediction ability of each stand-alone metamodel and thus decrease the risk of adopting inappropriate metamodels. Then, the NSGA-II is used to facilitate design space exploration. Besides, the main effects and contribution rates of process parameters on bead profile are analyzed. Eventually, the verification experiments of the obtained optima are carried out and compared with the un-optimized weld seam for bead geometries, weld appearances, and welding defects. Results illustrate that the proposed hybrid approach exhibits great capability of improving welding quality in LAW.

  15. 316L stainless steel tubes corrosion influenced by SRB in sea water

    SciTech Connect

    Yoffe, P.

    1997-08-01

    A tube made from SS316L was attacked by stagnated sea water. The typical onion form of the pits were obscured in welded and unwelded sectors of the tube. Iron sulfides FeS{sub 1{minus}x} and FeS{sub 2} (in pyrite form) were observed on effected surface of the tube, in addition to iron chloride and oxide/hydroxide. Theoretical investigation was based on cluster model of alloy and thermodynamic/kinetic characterization of possible reactions. It was concluded that microbially influenced sulfidizing played an accelerating role in the failure that exhibited the typical characteristics for stagnated sea water effect to chromium-nickel stainless steel.

  16. Fine structure analysis of biocompatible ceramic materials based hydroxyapatite and metallic biomaterials 316L

    NASA Astrophysics Data System (ADS)

    Anghelina, F. V.; Ungureanu, D. N.; Bratu, V.; Popescu, I. N.; Rusanescu, C. O.

    2013-11-01

    The aim of this paper was to obtain and characterize (surface morphology and fine structure) two types of materials: Ca10(PO4)6(OH)2 hydroxyapatite powder (HAp) as biocompatible ceramic materials and AISI 316L austenitic stainless steels as metallic biomaterials, which are the components of the metal-ceramic composites used for medical implants in reconstructive surgery and prosthetic treatment. The HAp was synthesized by coprecipitation method, heat treated at 200 °C, 800 °C and 1200 °C for 4 h, analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The stainless steel 316L type was made by casting, annealing and machined with a low speed (100 mm/s) in order to obtain a smooth surface and after that has been studied from residual stresses point of view in three polishing regimes conditions: at low speed polishing (150 rpm), at high speed polishing (1500 rpm) and high speed-vibration contact polishing (1500 rpm) using wide angle X-ray diffractions (WAXD). The chemical compositions of AISI 316 steel samples were measured using a Foundry Master Spectrometer equipped with CCD detector for spectral lines and the sparking spots of AISI 316L samples were analyzed using SEM. By XRD the phases of HAp powders have been identified and also the degree of crystallinity and average size of crystallites, and with SEM, we studied the morphology of the HAp. It has been found from XRD analysis that we obtained HAp with a high degree of crystallinity at 800 °C and 1200 °C, no presence of impurity and from SEM analysis we noticed the influence of heat treatment on the ceramic particles morphology. From the study of residual stress profiles of 316L samples were observed that it differs substantially for different machining regimes and from the SEM analysis of sparking spots we revealed the rough surfaces of stainless steel rods necessary for a better adhesion of HAp on it.

  17. Upset welded 304L and 316L vessels for storage tests

    SciTech Connect

    Kanne, W.R. Jr.

    1996-04-01

    Two sets of vessels for tritium storage tests were fabricated using upset welding. A solid-state resistance upset weld was used to join the two halves of each vessel at the girth. The vessels differ from production reservoirs in design, material, and fabrication process. One set was made from forged 304L stainless steel and the other from forged 316L stainless steel. Six vessels of each type were loaded with a tritium mix in November 1995 and placed in storage at 71 C. This memo describes and documents the fabrication of the twelve vessels.

  18. Mechanical and physical behavior of newly developed functionally graded materials and composites of stainless steel 316L with calcium silicate and hydroxyapatite.

    PubMed

    Ataollahi Oshkour, Azim; Pramanik, Sumit; Mehrali, Mehdi; Yau, Yat Huang; Tarlochan, Faris; Abu Osman, Noor Azuan

    2015-09-01

    This study aimed to investigate the structural, physical and mechanical behavior of composites and functionally graded materials (FGMs) made of stainless steel (SS-316L)/hydroxyapatite (HA) and SS-316L/calcium silicate (CS) employing powder metallurgical solid state sintering. The structural analysis using X-ray diffraction showed that the sintering at high temperature led to the reaction between compounds of the SS-316L and HA, while SS-316L and CS remained intact during the sintering process in composites of SS-316L/CS. A dimensional expansion was found in the composites made of 40 and 50 wt% HA. The minimum shrinkage was emerged in 50 wt% CS composite, while the maximum shrinkage was revealed in samples with pure SS-316L, HA and CS. Compressive mechanical properties of SS-316L/HA decreased sharply with increasing of HA content up to 20 wt% and gradually with CS content up to 50 wt% for SS-316L/CS composites. The mechanical properties of the FGM of SS-316L/HA dropped with increase in temperature, while it was improved for the FGM of SS-316L/CS with temperature enhancement. It has been found that the FGMs emerged a better compressive mechanical properties compared to both the composite systems. Therefore, the SS-316L/CS composites and their FGMs have superior compressive mechanical properties to the SS-316L/HA composites and their FGMs and also the newly developed FGMs of SS-316L/CS with improved mechanical and enhanced gradation in physical and structural properties can potentially be utilized in the components with load-bearing application.

  19. Simulations of spall experiments in 316L stainless steel conducted with square and triangular waves

    NASA Astrophysics Data System (ADS)

    Seaman, Lynn; Gray, G. T.(Rusty), III

    2005-07-01

    Triangular stress waves are more like those from applications (laser, explosives, nuclear) but laboratory experiments for studying spall damage generally provide square-topped waves. Gray et al (2003) performed four impact experiments in 316L stainless steel, two with square waves and two with triangular, achieving void damage in all but the lower-stress (6.6 GPa) triangular-wave sample. Simulations with the nucleation-and-growth model DFRACT exhibit fair correspondence with the damage in those tests showing damage, but also indicate damage in the triangular-wave test showing no damage. We are examining mechanisms which may delay the initiation of void damage or otherwise alter the expected damage processes in the model. Reference: G.T. (Rusty) Gray III, N. K. Bourne, B.L. Henrie, and J.C.F. Millet, Influence of Shock-Wave Profile Shape (Triangular ``Taylor-Wave'' versus Square-Topped) on the Spallation Response of 316L Stainless Steel, J. Phys. IV France 110 (2003), page 773-778,

  20. Hydrogen transport and solubility in 316L and 1.4914 steels for fusion reactor applications

    NASA Astrophysics Data System (ADS)

    Forcey, K. S.; Ross, D. K.; Simpson, J. C. B.; Evans, D. S.

    1988-12-01

    Equations are given which describe the permeation rate, diffusivity and solubility of hydrogen over the range 250-600°C at pressures up to 10 5Pa for the 316L stainless and modified 1.4914 martensitic candidate steels proposed for the construction of the Next European Torus (NET). For heat-treated 316L steel, the permeation rates measured agreed well with previous work and did not vary significantly from specimen to specimen or from batch to batch. Measurements of the permeation rate of hydrogen and deuterium through the modified 1.4914 steel, believed to be the first made, show that the martensitic steel is significantly more permeable than the austenitic steel, by an order of magnitude at 250°C and a factor of five at 600°C. This difference could make it necessary to use permeation barriers on critical components made from the martensitic steel in order to reduce the tritium permeation rate to acceptable levels.

  1. Corrosion of type 316L stainless steel in a mercury thermal convection loop

    SciTech Connect

    DiStefano, J.R.; Manneschmidt, E.T.; Pawel, S.J.

    1999-04-01

    Two thermal convection loops fabricated from 316L stainless steel containing mercury (Hg) and Hg with 1000 wppm gallium (Ga), respectively, were operated continuously for about 5000 h. In each case, the maximum loop temperature was constant at about 305 degrees C and the minimum temperature was constant at about 242 degrees C. Coupons in the hot leg of the Hg-loop developed a posous surface layer substantially depleted of nickel and chromium, which resulted in a transformation to ferrite. The coupon exposed at the top of the hot leg in the Hg-loop experienced the maximum degradation, exhibiting a surface layer extending an average of 9-10 mu m after almost 5000 h. Analysis of the corrosion rate data as a function of temperature (position) in the Hg-loop suggests wetting by the mer cury occurred only above about 255 degrees C and that the rate limiting step in the corrosion process above 255 degrees C is solute diffusion through the saturated liquid boundary layer adjacent to the corroding surface. The latter factor suggests that the corrosion of 316L stainless steel in a mercury loop may be velocity dependent. No wetting and no corrosion were observed on the coupons and wall specimens removed from the Hg/Ga loop after 5000 h of operation.

  2. The effect of surface roughness on the fretting corrosion of 316L stainless steel biomaterial surfaces

    NASA Astrophysics Data System (ADS)

    Shenoy, Aarti

    The medical device industry is still seeking answers to the mechanically-assisted corrosion (MAC) problem, which becomes increasingly important due to modularity in design. MAC manifests in various forms, some of which are fretting corrosion, crevice corrosion and stress corrosion. Several studies have been conducted to understand the causes and the factors that affect fretting corrosion. Some of the factors are the applied load, surface potential, oxide film characteristics and solution chemistry near the interface. Surface properties such as surface roughness determine the topography of the surface and the nature of asperity-asperity contact, which is a factor that would determine the mechanically assisted corrosion behavior of the interface, like the stem-neck and head-neck taper junctions in modular hip replacement devices. This study aims to understand the correlation between surface roughness of 316L stainless steel samples and fretting corrosion behavior using a variable load pin-on-disc test. It was found that the smoother surfaces are associated with lower fretting currents. However, smoother surfaces also created the conditions for fretting initiated crevice corrosion to occur more readily. Fretting corrosion regimes and the severity are thus dependent upon the surface roughness. A possible explanation could be due to the inverse relationship between the interasperity distance parameter, Delta, and fretting currents. The coefficient of friction between the two surfaces in contact however remained unaffected by surface roughness, but decreased with increasing load. Smoother surfaces, while lowering fretting corrosion reactions can enhance crevice corrosion reactions in 316L stainless steel interfaces.

  3. Strain rate dependence of impact properties of sintered 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Lee, Woei-Shyan; Lin, Chi-Feng; Liu, Tsung-Ju

    2006-12-01

    This paper uses a material testing system (MTS) and a compressive split-Hopkinson bar to investigate the impact behaviour of sintered 316L stainless steel at strain rates ranging from 10 -3 s -1 to 7.5 × 10 3 s -1. It is found that the true stress, the rate of work hardening and the strain rate sensitivity vary significantly as the strain rate increases. The flow behaviour of the sintered 316L stainless steel can be accurately predicted using a constitutive law based on Gurson's yield criterion and the flow rule proposed by Khan, Huang and Liang (KHL). Microstructural observations reveal that the degree of localized grain deformation increases, but the pore density and the grain size decrease, with increasing strain rate. Adiabatic shear bands associated with cracking are developed at strain rates higher than 5.6 × 10 3 s -1. The fracture surfaces exhibit ductile dimples. The depth and density of these dimples decrease with increasing strain rate.

  4. Inhalation toxicity of 316L stainless steel powder in relation to bioaccessibility.

    PubMed

    Stockmann-Juvala, H; Hedberg, Y; Dhinsa, N K; Griffiths, D R; Brooks, P N; Zitting, A; Wallinder, I Odnevall; Santonen, T

    2013-11-01

    The Globally Harmonized System for Classification and Labelling of Chemicals (GHS) considers metallic alloys, such as nickel (Ni)-containing stainless steel (SS), as mixtures of substances, without considering that alloys behave differently compared to their constituent metals. This study presents an approach using metal release, explained by surface compositional data, for the prediction of inhalation toxicity of SS AISI 316L. The release of Ni into synthetic biological fluids is >1000-fold lower from the SS powder than from Ni metal, due to the chromium(III)-rich surface oxide of SS. Thus, it was hypothesized that the inhalation toxicity of SS is significantly lower than what could be predicted based on Ni metal content. A 28-day inhalation study with rats exposed to SS 316L powder (<4 µm, mass median aerodynamic diameter 2.5-3.0 µm) at concentrations up to 1.0 mg/L showed accumulation of metal particles in the lung lobes, but no signs of inflammation, although Ni metal caused lung toxicity in a similar published study at significantly lower concentrations. It was concluded that the bioaccessible (released) fraction, rather than the elemental nominal composition, predicts the toxicity of SS powder. The study provides a basis for an approach for future validation, standardization and risk assessment of metal alloys.

  5. Partially degradable friction-welded pure iron-stainless steel 316L bone pin.

    PubMed

    Nasution, A K; Murni, N S; Sing, N B; Idris, M H; Hermawan, H

    2015-01-01

    This article describes the development of a partially degradable metal bone pin, proposed to minimize the occurrence of bone refracture by avoiding the creation of holes in the bone after pin removal procedure. The pin was made by friction welding and composed of two parts: the degradable part that remains in the bone and the nondegradable part that will be removed as usual. Rods of stainless steel 316L (nondegradable) and pure iron (degradable) were friction welded at the optimum parameters: forging pressure = 33.2 kPa, friction time = 25 s, burn-off length = 15 mm, and heat input = 4.58 J/s. The optimum tensile strength and elongation was registered at 666 MPa and 13%, respectively. A spiral defect formation was identified as the cause for the ductile fracture of the weld joint. A 40-µm wide intermetallic zone was identified along the fusion line having a distinct composition of Cr, Ni, and Mo. The corrosion rate of the pin gradually decreased from the undeformed zone of pure iron to the undeformed zone of stainless steel 316L. All metallurgical zones of the pin showed no toxic effect toward normal human osteoblast cells, confirming the ppb level of released Cr and Ni detected in the cell media were tolerable.

  6. Effect of Mercury Velocity on Corrosion of Type 316L Stainless Steel in a Thermal Convection Loop

    SciTech Connect

    Pawel, SJ

    2001-03-23

    Two 316L thermal convection loops (TCLs) containing several types of 316L specimens circulated mercury continuously for 2000 h at a maximum temperature of 300 C. Each TCL was fitted with a venturi-shaped reduced section near the top of the hot leg for the purpose of locally increasing the Hg velocity. Results suggest that an increase in velocity from about 1.2 m/min (bulk flow) to about 5 mmin (reduced section) had no significant impact on compatibility of 316L with Hg. In addition, various surface treatments such as gold-plating, chemical etching, polishing, and steam cleaning resulted in little or no influence on compatibility of 316L with Hg when compared to nominal mill-annealed/surface-ground material. A sensitizing heat treatment also had little/no effect on compatibility of 316L with Hg for the bulk specimen, although intergranular attack was observed around the specimen holes in each case. It was determined that carburization of the hole area had occurred as a result of the specimen fabrication process potentially rendering the specimens susceptible to corrosion by Hg at these locations. To avoid sensitization-related compatibility issues for SNS components, selection of low carbon grades of stainless steel and control of the fabrication process is recommended.

  7. The tensile properties of AISI 316L and OPTIFER in various conditions irradiated in a spallation environment

    NASA Astrophysics Data System (ADS)

    Chen, J.; Rödig, M.; Carsughi, F.; Dai, Y.; Bauer, G. S.; Ullmaier, H.

    2005-08-01

    Tensile specimens, prepared from AISI 316L austenitic stainless steel in three conditions (solution-annealed, cold-worked and electron-beam welded) and from OPTIFER martensitic stainless steel in tempered condition, were irradiated in the Swiss spallation neutron source (SINQ) at 90-400 °C to displacement doses from 3 dpa to 11 dpa. The mechanical properties were measured by tensile testing at room temperature and 250 °C, respectively, and subsequent metallographic analysis was employed. The tensile results indicated that the strength of AISI 316L-SA is quite similar or a little higher than in 316L-EBW but elongation of SA 316L is somewhat larger than EBW for both unirradiated and irradiated samples. The cold-worked specimens revealed much higher strength but almost zero strain-to-necking after irradiation. The results from OPTIFER samples showed that irradiation hardening increases with dose, which is accompanied by a dramatic reduction of uniform elongation beginning at very low dose. The metallographic analysis showed that the samples of AISI 316L-EBW failed in the welded zone.

  8. Effect of surface passivation on corrosion resistance and antibacterial properties of Cu-bearing 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Zhao, Jinlong; Xu, Dake; Shahzad, M. Babar; Kang, Qiang; Sun, Ying; Sun, Ziqing; Zhang, Shuyuan; Ren, Ling; Yang, Chunguang; Yang, Ke

    2016-11-01

    The resistance for pitting corrosion, passive film stability and antibacterial performance of 316L-Cu SS passivated by nitric acid solution containing certain concentration of copper sulfate, were studied by electrochemical cyclic polarization, electrochemical impedance spectroscopy (EIS) and co-culture with bacteria. Inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze the Cu2+ ions release from 316L-Cu SS surface. XPS analysis proved that the enrichment of CuO, Cr2O3 and Cr(OH)3 on the surface of specimen could simultaneously guarantee a better corrosion resistance and stable antibacterial properties. The biocompatibility evaluation determined by RTCA assay also indicated that the 316L-Cu SS after antibacterial passivation was completely biocompatible.

  9. Rapid heating tensile tests of hydrogen-charged high-energy-rate-forged 316L stainless steel

    SciTech Connect

    Mosley, W.C.

    1989-05-19

    316L stainless steel is a candidate material for construction of equipment that will be exposed to tritium. Proper design of the equipment will require an understanding of how tritium and its decay product helium affect mechanical properties. This memorandum describes results of rapid heating tensile testing of hydrogen-charged specimens of high-energy-rate-forged (HERF) 316L stainless steel. These results provide a data base for comparison with uncharged and tritium-charged-and-aged specimens to distinguish the effects of hydrogen and helium. Details of the experimental equipment and procedures and results for uncharged specimens were reported previously. 3 refs., 10 figs.

  10. Improved corrosion resistance of 316L stainless steel by nanocrystalline and electrochemical nitridation in artificial saliva solution

    NASA Astrophysics Data System (ADS)

    Lv, Jinlong; Liang, Tongxiang

    2015-12-01

    The fluoride ion in artificial saliva significantly changed semiconductor characteristic of the passive film formed on the surface of 316L stainless steels. The electrochemical results showed that nanocrystalline α‧-martensite improved corrosion resistance of the stainless steel in a typical artificial saliva compared with coarse grained stainless steel. Moreover, comparing with nitrided coarse grained stainless steel, corrosion resistance of the nitrided nanocrystalline stainless steel was also improved significantly, even in artificial saliva solution containing fluoride ion. The present study showed that the cryogenic cold rolling and electrochemical nitridation improved corrosion resistance of 316L stainless steel for the dental application.

  11. Fatigue life assessment of 316L stainless steel and DIN-1.4914 martensitic steel before and after TEXTOR exposure

    NASA Astrophysics Data System (ADS)

    Shakib, J. I.; Ullmaier, H.; Little, E. A.; Schmitz, W.; Faulkner, R. G.; Chung, T. E.

    1992-09-01

    The effects of plasma exposure in the TEXTOR tokomak on elevated temperature fatigue lifetime and failure micromechanisms of 316L austenitic stainless steel and DIN 1.4914 martensitic steel (NET reference heats) have been evaluated. Fatigue tests were carried out in vacuum in the temperature range 150°-450°C and compared with data from reference specimens.Plasma-induced surface modifications lead to significant deterioration in fatigue life of 316L steel, whereas the lifetime of 1.4914 steel is unaffected. Fatigue in the 1.4914 steel is surface-initiated only at high stresses. At low stress amplitudes internal fatigue initiation at inclusions was observed.

  12. Material Corrosion and Plate-Out Test of Types 304L and 316L Stainless Steel

    SciTech Connect

    Zapp, P.E.

    2001-02-06

    Corrosion and plate-out tests were performed on 304L and 316L stainless steel in pretreated Envelope B and Envelope C solutions. Flat coupons of the two stainless steels were exposed to 100 degrees C liquid and to 74 degrees C and 88 degrees C vapor above the solutions for 61 days. No significant corrosion was observed either by weight-loss measurements or by microscopic examination. Most coupons had small weight gains due to plate-out of solids, which remained to some extent even after 24-hour immersion in 1 N nitric acid at room temperature. Plate-out was more significant in the Envelope B coupons, with film thickness from less than 0.001 in. to 0.003-inches.

  13. Roughness Reduction in AISI 316L Stainless Steel after Surface Mechanical Attrition Treatment (SMAT)

    NASA Astrophysics Data System (ADS)

    Arifvianto, B.; Suyitno, Suyitno; Mahardika, M.

    2011-12-01

    Surface mechanical attrition treatment (SMAT) enhances the strength of metals by generating nanocrystallites at the surface layer. During the treatment, multiple impacts of milling balls are subjected to the treated surface. Consequently, the structure and roughness of the treated surface are also modified. In this paper, the effect of SMAT on the surface structure and roughness of an initially rough AISI 316L stainless steel is investigated. The SMAT was conducted for 0-20 minutes. The surface morphology, roughness, and volume loss due to the SMAT were studied. The result shows a decreasing roughness by the SMAT. An apparently deformed structure is also observed after 15 minutes of the treatment. However, no significant change in the volume loss is reported due to this treatment. Deformation by the multiple impacts is proposed to be the mechanism of the roughness reduction instead of microcutting by the milling balls during the SMAT.

  14. Dissolution of a 316L stainless steel vessel by a pool of molten aluminum

    SciTech Connect

    Tutu, N.K.; Finfrock, C.C.; Lara, J.D.; Schwarz, C.E.; Greene, G.A.

    1993-01-01

    Two experiments to study the dissolution of a torospherical stainless steel vessel by an isothermal pool of molten aluminum have been performed. The test vessels consisted of 24 inch diameter 316L stainless steel ``ASME Flanged and Dished Heads.`` The nominal values of the average melt temperatures for the two tests were: 977{degree}C and 1007{degree}C. The measurements of the dissolution depth as a function of the position along the vessel surface showed the dissolution to be spatially highly non-uniform. Large variations in the dissolution depth with respect to the azimuthal coordinate were also observed. The maximum value of the measured time averaged dissolution rate was found to be 5.05 mm/hr, and this occurred near the edge of the molten pool. The concentration measurements indicated that the molten pool was highly stratified with respect to the concentration of stainless steel in the melt (molten aluminum-stainless steel solution).

  15. Cytocompatibility and mechanical properties of novel porous 316 L stainless steel.

    PubMed

    Kato, Komei; Yamamoto, Akiko; Ochiai, Shojiro; Wada, Masahiro; Daigo, Yuzo; Kita, Koichi; Omori, Kenichi

    2013-07-01

    Novel 316 L stainless steel (SS) foam with 85% porosity and an open pore diameter of 70-440 μm was developed for hard tissue application. The foam sheet with a 200-μm diameter had superior cell proliferation and penetration as identified through in vitro experiments. Calcification of human osteosarcoma cells in the SS foam was observed. Multi-layered foam preparation is a potential alternative technique that satisfies multi-functional requirements such as cell penetration and binding strength to the solid metal. In tensile tests, Young's modulus and the strength of the SS foam were 4.0 GPa and 11.2 MPa respectively, which is comparable with human cancellous bone. PMID:23623090

  16. Anticoagulant surface of 316 L stainless steel modified by surface-initiated atom transfer radical polymerization.

    PubMed

    Guo, Weihua; Zhu, Jian; Cheng, Zhenping; Zhang, Zhengbiao; Zhu, Xiulin

    2011-05-01

    Polished 316 L stainless steel (SS) was first treated with air plasma to enhance surface hydrophilicity and was subsequently allowed to react with 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane to introduce an atom transfer radical polymerization (ATRP) initiator. Accordingly, the surface-initiated atom transfer radical polymerization of polyethylene glycol methacrylate (PEGMA) was carried out on the surface of the modified SS. The grafting progress was monitored by water contact angle measurements, X-ray photoelectron spectroscopy and atomic force microscopy. The polymer thickness as a function different polymerization times was characterized using a step profiler. The anticoagulative properties of the PEGMA modified SS surface were investigated. The results showed enhanced anticoagulative to acid-citrate-dextrose (ACD) blood after grafting PEGMA on the SS surface. PMID:21528878

  17. Mechanical and Electrochemical Characterization of Super-Solidus Sintered Austenitic Stainless Steel (316L)

    NASA Astrophysics Data System (ADS)

    Muthuchamy, A.; Raja Annamalai, A.; Ranka, Rishabh

    2016-08-01

    The present study compares the mechanical and electrochemical behaviour of austenitic (AISI 316L) stainless steel compacted at various pressures (200, 400 and 600 MPa) and conventionally sintered at super-solidus temperature of 1,400°C. The electrochemical behaviour was investigated in 0.1 N H2SO4 solution by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The shrinkage decreased and densification has been increased with increasing pressure. The mechanical and electrochemical behaviour with pressure has been correlated with densification response and microstructure (pore type, volume and morphology). Highest densification (~92% theoretical) achieved at 600 MPa (compaction pressure) and 1,400°C (sintering temperature) resulted in excellent combination of tensile strength and ductility (456 ± 40 MPa, 25 ± 1.1%), while showing excellent corrosion resistance (0.1 mmpy or 4.7 mpy).

  18. A Shear Strain Route Dependency of Martensite Formation in 316L Stainless Steel.

    PubMed

    Kang, Suk Hoon; Kim, Tae Kyu; Jang, Jinsung; Oh, Kyu Hwan

    2015-06-01

    In this study, the effect of simple shearing on microstructure evolution and mechanical properties of 316L austenitic stainless steel were investigated. Two different shear strain routes were obtained by twisting cylindrical specimens in the forward and backward directions. The strain-induced martensite phase was effectively obtained by alteration of the routes. Formation of the martensite phase clearly resulted in significant hardening of the steel. Grain-size reduction and strain-induced martensitic transformation within the deformed structures of the strained specimens were characterized by scanning electron microscopy - electron back-scattered diffraction, X-ray diffraction, and the TEM-ASTAR (transmission electron microscopy - analytical scanning transmission atomic resolution, automatic crystal orientation/phase mapping for TEM) system. Significant numbers of twin networks were formed by alteration of the shear strain routes, and the martensite phases were nucleated at the twin interfaces.

  19. Controlling the electrodeposition, morphology and structure of hydroxyapatite coating on 316L stainless steel.

    PubMed

    Thanh, Dinh Thi Mai; Nam, Pham Thi; Phuong, Nguyen Thu; Que, Le Xuan; Anh, Nguyen Van; Hoang, Thai; Lam, Tran Dai

    2013-05-01

    Hydroxyapatite (HAp) coatings were prepared on 316L stainless steel (316LSS) substrates by electrochemical deposition in the solutions containing Ca(NO3)2·4H2O and NH4H2PO4 at different electrolyte concentrations. Along with the effect of precursor concentration, the influence of temperature and H2O2 content on the morphology, structure and composition of the coating was thoroughly discussed with the help of X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectra. The in vitro tests in simulated body fluids (SBF) were carried out and then the morphological and structural changes were estimated by SEM and electrochemical techniques (open circuit potential, polarization curves, Nyquist and Bode spectra measurements). Being simple and cost-effective, this method is advantageous for producing HAp implant materials with good properties/characteristics, aiming towards in vivo biomedical applications.

  20. Relative Defect Density Measurements of Laser Shock Peened 316L Stainless Steel Using Positron Annihilation Spectroscopy

    SciTech Connect

    Marcus A. Gagliardi; Bulent H. Sencer; A. W. Hunt; Stuart A. Maloy; George T. Gray III

    2011-12-01

    The surface of an annealed 316L stainless steel coupon was laser shock peened and Vickers hardness measurements were subsequently taken of its surface. This Vickers hardness data was compared with measurements taken using the technique of positron annihilation Doppler broadening spectroscopy. When compared, a correlation was found between the Vickers hardness data measurements and those made using Doppler broadening spectroscopy. Although materials with a high defect density can cause the S-parameter measurements to saturate, variations in the Sparameter measurements suggest that through further research the Doppler broadening technique could be used as a viable alternative to measuring a material's hardness. In turn, this technique, could be useful in industrial settings where surface hardness and surface defects are used to predict lifetime of components.

  1. Effect of Laser Peening without Coating on 316L austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Sathyajith, S.; kalainathan, S.

    2015-02-01

    Laser Peening without Coating (LPwC) is an innovative surface modification technique used for the in-suit preventive maintenance of nuclear reactor components using frequency doubled (green) laser. The advantage of LPwC is that the laser required for this technique is in milli joule range and the processes can perform in aqueous environment. This paper discussed the effect of LPwC on 316L austenitic stainless steel using low energy Nd: YAG laser with various laser pulse density. The base specimen and laser peened specimen were subjected to surface residual stress, surface morphology, micro hardness and potentiodynamic polarization studies. The laser peened surface exhibit significant improvement in surface compressive residual stress. The depth profile of micro hardness revealed higher strain hardening on laser peened specimens. Though corrosion potential reported an anodic shift,current density is found to be increased after LPwC for the specimen peened with higher pulse density.

  2. Effects of dissolved oxygen on electrochemical and semiconductor properties of 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Feng, Zhicao; Cheng, Xuequn; Dong, Chaofang; Xu, Lin; Li, Xiaogang

    2010-12-01

    The effects of dissolved oxygen on the electrochemical behavior and semiconductor properties of passive film formed on 316L SS in three solutions with different dissolved oxygen were studied by using polarization curve, Mott-Schottky analysis and the point defect model (PDM). The results show that higher dissolved oxygen accelerates both anodic and cathodic process. Based on Mott-Schottky analysis and PDM, the key parameters for passive film, donor density Nd, flat-band potential Efb and diffusivity of defects D0 were calculated. The results display that Nd(1-7 × 10 27 m -3) and D0(1-18 × 10 -16 cm 2/s) increase and Efb value reduces with the dissolved oxygen in solution.

  3. Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings

    PubMed Central

    Jones, John Eric; Chen, Meng; Yu, Qingsong

    2015-01-01

    To improve their corrosion resistance and thus long-term biocompatibility, 316L stainless steel coronary artery stents were coated with trimethylsilane (TMS) plasma coatings of 20–25 nm in thickness. Both direct current (DC) and radio-frequency (RF) glow discharges were utilized for TMS plasma coatings and additional NH3/O2 plasma treatment to tailor the surface properties. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that both DC and RF TMS plasma coatings had Si- and C-rich composition, and the O-and N-contents on the surfaces were substantially increased after NH3/O2 plasma treatment. Surface contact angle measurements showed that DC TMS plasma nanocoating with NH3/O2 plasma treatment generated very hydrophilic surface. The corrosion resistance of TMS plasma coated stents was evaluated through potentiodynamic polarization and electro-chemical impedance spectroscopy (EIS) techniques. The potentiodynamic polarization demonstrated that the TMS plasma coated stents imparted higher corrosion potential and pitting potential, as well as lower corrosion current densities as compared with uncoated controls. The surface morphology of stents before and after potentiodynamic polarization testing was analyzed with scanning electron microscopy, which indicated less corrosion on coated stents than uncoated controls. It was also noted that, from EIS data, the hydrophobic TMS plasma nanocoatings showed stable impedance modulus at 0.1 Hz after 21 day immersion in an electrolyte solution. These results suggest improved corrosion resistance of the 316L stainless steel stents by TMS plasma nanocoatings and great promise in reducing and blocking metallic ions releasing into the bloodstream. PMID:24500866

  4. Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings.

    PubMed

    Eric Jones, John; Chen, Meng; Yu, Qingsong

    2014-10-01

    To improve their corrosion resistance and thus long-term biocompatibility, 316L stainless steel coronary artery stents were coated with trimethylsilane (TMS) plasma coatings of 20-25 nm in thickness. Both direct current (DC) and radio-frequency (RF) glow discharges were utilized for TMS plasma coatings and additional NH₃/O₂ plasma treatment to tailor the surface properties. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that both DC and RF TMS plasma coatings had Si- and C-rich composition, and the O- and N-contents on the surfaces were substantially increased after NH₃/O₂ plasma treatment. Surface contact angle measurements showed that DC TMS plasma nanocoating with NH₃/O₂ plasma treatment generated very hydrophilic surface. The corrosion resistance of TMS plasma coated stents was evaluated through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The potentiodynamic polarization demonstrated that the TMS plasma coated stents imparted higher corrosion potential and pitting potential, as well as lower corrosion current densities as compared with uncoated controls. The surface morphology of stents before and after potentiodynamic polarization testing was analyzed with scanning electron microscopy, which indicated less corrosion on coated stents than uncoated controls. It was also noted that, from EIS data, the hydrophobic TMS plasma nanocoatings showed stable impedance modulus at 0.1 Hz after 21 day immersion in an electrolyte solution. These results suggest improved corrosion resistance of the 316L stainless steel stents by TMS plasma nanocoatings and great promise in reducing and blocking metallic ions releasing into the bloodstream.

  5. Electrochemical and in vitro bioactivity of polypyrrole/ceramic nanocomposite coatings on 316L SS bio-implants.

    PubMed

    Madhan Kumar, A; Nagarajan, S; Ramakrishna, Suresh; Sudhagar, P; Kang, Yong Soo; Kim, Hyongbum; Gasem, Zuhair M; Rajendran, N

    2014-10-01

    The present investigation describes the versatile fabrication and characterization of a novel composite coating that consists of polypyrrole (PPy) and Nb2O5 nanoparticles. Integration of the two materials is achieved by electrochemical deposition on 316L stainless steel (SS) from an aqueous solution of oxalic acid containing pyrrole and Nb2O5 nanoparticles. Fourier transform infrared spectral (FTIR) and X-ray diffraction (XRD) studies revealed that the existence of Nb2O5 nanoparticles in PPy matrix with hexagonal structure. Surface morphological analysis showed that the presence of Nb2O5 nanoparticles strongly influenced the surface nature of the nanocomposite coated 316L SS. Micro hardness results revealed the enhanced mechanical properties of PPy nanocomposite coated 316L SS due to the addition of Nb2O5 nanoparticles. The electrochemical studies were carried out using cyclic polarization and electrochemical impedance spectroscopy (EIS) measurements. In order to evaluate the biocompatibility, contact angle measurements and in vitro characterization were performed in simulated body fluid (SBF) and on MG63 osteoblast cells. The results showed that the nanocomposite coatings exhibit superior biocompatibility and enhanced corrosion protection performance over 316L SS than pure PPy coatings.

  6. Effect of thermal exposure in helium on mechanical properties and microstructure of 316L and P91

    NASA Astrophysics Data System (ADS)

    Kunzova, Klara; Berka, Jan; Siegl, Jan; Hausild, Petr

    2016-04-01

    In this paper, the effects of high temperature exposure in air as well as in impure He on mechanical properties of 316L and P91 steels were investigated. The experimental programme was part of material design of new experimental facility - high temperature helium loop. Some of the specimens were exposed in air at 750 °C for up to 1000 h. Another set of specimens were exposed in impure helium containing 1 ppmv CO2, 2 ppmv O2, 35 ppmv CH4, 250 ppmv CO and 400 ppmv H2 at 750 °C for up to 1000 h. Metalographical analysis, tensile tests, fracture toughness and hardness tests of exposed and non-exposed specimens were carried out. After the exposure both in air and He, the ultimate tensile strength of P91 decreased significantly more than that of 316L. After the exposure in He, the fracture toughness of 316L was reduced to 60% while fracture toughness of P91 showed no significant changes. The hardness of P91 decreased with exposure time in air. The measurement of the hardness of 316L was very scattered the most probably due to the heterogeneities in microstructure, the trend was not possible to evaluate.

  7. A novel silica nanotube reinforced ionic incorporated hydroxyapatite composite coating on polypyrrole coated 316L SS for implant application.

    PubMed

    Prem Ananth, K; Joseph Nathanael, A; Jose, Sujin P; Oh, Tae Hwan; Mangalaraj, D

    2016-02-01

    An attempt has been made to deposit a novel smart ion (Sr, Zn, Mg) substituted hydroxyapatite (I-HAp) and silica nanotube (SiNTs) composite coatings on polypyrrole (PPy) coated surgical grade 316L stainless steel (316L SS) to improve its biocompatibility and corrosion resistance. The I-HAp/SiNTS/PPy bilayer coating on 316L SS was prepared by electrophoretic deposition technique. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies were carried out. These results confirmed the significant improvement of the corrosion resistance of the 316L SS alloy by the I-HAp/SiNTs/PPy bilayer composite coating. The adhesion strength and hardness test confirmed the anticipated mechanical properties of the composite. A low contact angle value revealed the hydrophilic nature. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) was used for the leach out analysis of the samples. Added to this, the bioactivity of the composite was analyzed by observing the apatite formation in the SBF solution for 7, 14, 21 and 28days of incubation. An enhancement of in vitro osteoblast attachment and cell viability was observed, which could lead to the optimistic orthopedic and dental applications.

  8. Effects of Heat Treatments on Microstructure Changes in The Interface of Cu/SS316L Joint Materials

    SciTech Connect

    Xu, Q.; Yoshiie, T.; Edwards, Danny J.

    2000-09-01

    In both joints iron and chromium diffused from the stainless steel into the copper alloy, producing a narrow zone of about a 15 ?m containing FeCr precipitates and small voids. Failure in some bending tests occurred by a crack propagating through this zone in a direction parallel to the interface, indicating that the formation of these precipitates may not be conducive to good joint properties. The results of annealing experiments showed that temperatures # 673 K did not change the initial microstructure or composition of CuAl25/SS316L and CuNiBe/SS316L joints. Although there are no data from annealing experiments longer than 100 hours, it is expected that the microstructure and composition of CuAl25/SS316L and CuNiBe/SS316L are stable under the thermal operating conditions of fusion reactors. However, irradiation may lead to significant changes because of radiation-enhanced segregation, precipitation or dissolution near and at the interface that could alter the properties. In addition, the preexisting voids near the interface of the joints may coarsen under irradiation and enhance the sensitivity of joints to failure. Given the uncertainties in the response to irradiation, neutron irradiation experiments should be performed at appropriate temperatures to investigate the response of the different materials.

  9. Characterization of irradiated AISI 316L stainless steel disks removed from the Spallation Neutron Source

    SciTech Connect

    Vevera, Bradley J; Hyres, James W; McClintock, David A; Riemer, Bernie

    2014-01-01

    Irradiated AISI 316L stainless steel disks were removed from the Spallation Neutron Source (SNS) for post-irradiation examination (PIE) to assess mechanical property changes due to radiation damage and erosion of the target vessel. Topics reviewed include high-resolution photography of the disk specimens, cleaning to remove mercury (Hg) residue and surface oxides, profile mapping of cavitation pits using high frequency ultrasonic testing (UT), high-resolution surface replication, and machining of test specimens using wire electrical discharge machining (EDM), tensile testing, Rockwell Superficial hardness testing, Vickers microhardness testing, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The effectiveness of the cleaning procedure was evident in the pre- and post-cleaning photography and permitted accurate placement of the test specimens on the disks. Due to the limited amount of material available and the unique geometry of the disks, machine fixturing and test specimen design were critical aspects of this work. Multiple designs were considered and refined during mock-up test runs on unirradiated disks. The techniques used to successfully machine and test the various specimens will be presented along with a summary of important findings from the laboratory examinations.

  10. Reduced graphene oxide growth on 316L stainless steel for medical applications

    NASA Astrophysics Data System (ADS)

    Cardenas, L.; MacLeod, J.; Lipton-Duffin, J.; Seifu, D. G.; Popescu, F.; Siaj, M.; Mantovani, D.; Rosei, F.

    2014-07-01

    We report a new method for the growth of reduced graphene oxide (rGO) on the 316L alloy of stainless steel (SS) and its relevance for biomedical applications. We demonstrate that electrochemical etching increases the concentration of metallic species on the surface and enables the growth of rGO. This result is supported through a combination of Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), density functional theory (DFT) calculations and static water contact angle measurements. Raman spectroscopy identifies the G and D bands for oxidized species of graphene at 1595 cm-1 and 1350 cm-1, respectively, and gives an ID/IG ratio of 1.2, indicating a moderate degree of oxidation. XPS shows -OH and -COOH groups in the rGO stoichiometry and static contact angle measurements confirm the wettability of rGO. SEM and AFM measurements were performed on different substrates before and after coronene treatment to confirm rGO growth. Cell viability studies reveal that these rGO coatings do not have toxic effects on mammalian cells, making this material suitable for biomedical and biotechnological applications.

  11. Reduced graphene oxide growth on 316L stainless steel for medical applications.

    PubMed

    Cardenas, L; MacLeod, J; Lipton-Duffin, J; Seifu, D G; Popescu, F; Siaj, M; Mantovani, D; Rosei, F

    2014-08-01

    We report a new method for the growth of reduced graphene oxide (rGO) on the 316L alloy of stainless steel (SS) and its relevance for biomedical applications. We demonstrate that electrochemical etching increases the concentration of metallic species on the surface and enables the growth of rGO. This result is supported through a combination of Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), density functional theory (DFT) calculations and static water contact angle measurements. Raman spectroscopy identifies the G and D bands for oxidized species of graphene at 1595 cm(-1) and 1350 cm(-1), respectively, and gives an ID/IG ratio of 1.2, indicating a moderate degree of oxidation. XPS shows -OH and -COOH groups in the rGO stoichiometry and static contact angle measurements confirm the wettability of rGO. SEM and AFM measurements were performed on different substrates before and after coronene treatment to confirm rGO growth. Cell viability studies reveal that these rGO coatings do not have toxic effects on mammalian cells, making this material suitable for biomedical and biotechnological applications.

  12. SCC crack growth rate of cold worked 316L stainless steel in PWR environment

    NASA Astrophysics Data System (ADS)

    Du, Donghai; Chen, Kai; Yu, Lun; lu, Hui; Zhang, Lefu; Shi, Xiuqiang; Xu, Xuelian

    2015-01-01

    Many component failures in nuclear power plants were found to be caused by stress corrosion cracking (SCC) of cold worked austenitic steels. Some of the pressure boundary component materials are even cold worked up to 35% plastic deformation, leaving high residual stress and inducing high growth rate of corrosion crack. Controlling water chemistry is one of the best counter measure to mitigate this problem. In this work, the effects of temperature (200 up to 325 °C) and dissolved oxygen (0 up to 2000 μg/L) on SCC crack growth rates of cold worked austenitic stainless steel type 316L have been tested by using direct current potential drop (DCPD) method. The results showed that temperature affected SCC crack growth rates more significantly in oxygenated water than in deaerated water. In argon deaerated water, the crack growth rate exhibited a peak at about 250 °C, which needs further verification. At 325 °C, the SCC crack growth rate increased rapidly with the increase of dissolved oxygen concentration within the range from 0 up to 200 μg/L, while when dissolved oxygen was above 200 μg/L, the crack growth rate followed a shallower dependence on dissolved oxygen concentration.

  13. Electrophoretic deposition of bioactive glass coating on 316L stainless steel and electrochemical behavior study

    NASA Astrophysics Data System (ADS)

    Mehdipour, Mehrad; Afshar, Abdollah; Mohebali, Milad

    2012-10-01

    In this research, submicron bioactive glass (BG) particles were synthesized by a sol-gel process and were then coated on a 316L stainless steel substrate using an electrophoretic deposition (EPD) technique. Stable suspension of bioactive glass powders in ethanol solvent was prepared by addition of triethanol amine (TEA), which increased zeta potential from 16.5 ± 1.6 to 20.3 ± 1.4 (mv). Thickness, structure and electrochemical behavior of the coating were characterized. SEM studies showed that increasing EPD voltage leads to a coating with more agglomerated particles, augmented porosity and micro cracks. The results of Fourier transformed infrared (FTIR) spectroscopy revealed the adsorption of TEA via methyl and amid groups on bioactive glass particles. Presence of bioactive glass coating reduced corrosion current density (icorr) and shifted corrosion potential (Ecorr) toward more noble values in artificial saliva at room temperature. Percent porosity of the coating measured by potentiodynamic polarization technique increased as EPD voltage was raised. The results of impedance spectroscopic studies demonstrated that the coating acts as a barrier layer in artificial saliva.

  14. Corrosion Resistance of Ti-O Film Modified 316L Stainless Steel Coronary Stents In Vitro

    NASA Astrophysics Data System (ADS)

    Liu, Hengquan; Leng, Yongxiang; Huang, Nan

    2012-03-01

    This article dealt with improving corrosion resistance of stent modified using Ti-O film. Ti-O films of various thicknesses were grown on the surface of 316L stainless steel (SS) stents by metal vacuum arc source deposition technology, and the phase composition, the thickness and the adhesion between films and substance were investigated by micro-x-ray diffraction (Micro-XRD), surface profilometer, and scanning electron microscopy (SEM) separately. The corrosion resistance of modified stent was assessed by polarization test in phosphate buffered solution (37 ± 1 °C). The result shows that the Ti-O films were very smooth and uniform. There were not any cracks and delaminations after dilation by angioplasty, the adhesion between Ti-O film and stent is satisfactory. The open circuit potential (OCP) of the Ti-O film modified stents was higher than that of the bare stents; it shows that the electrochemical stability of modified stents was more than bare stents. The polarization test result indicates that the passivation stability and anti-breakdown performance of Ti-O film stents had better than bare stents, and no pitting was observed on the surface of both modified stents, but the local film striations were found on the stent surface of the thicker film, which indicated that the Ti-O film stents with certain thickness has good corrosion resistance.

  15. Computaional Modeling of the Stability of Crevice Corrosion of Wetted SS316L

    SciTech Connect

    F. Cui; F.J. Presuel-Moreno; R.G. Kelly

    2006-04-17

    The stability of localized corrosion sites on SS 316L exposed to atmospheric conditions was studied computationally. The localized corrosion system was decoupled computationally by considering the wetted cathode and the crevice anode separately and linking them via a constant potential boundary condition at the mouth of the crevice. The potential of interest for stability was the repassivation potential. The limitations on the ability of the cathode that are inherent due to the restricted geometry were assessed in terms of the dependence on physical and electrochemical parameters. Physical parameters studied include temperature, electrolyte layer thickness, solution conductivity, and the size of the cathode, as well as the crevice gap for the anode. The current demand of the crevice was determined considering a constant crevice solution composition that simulates the critical crevice solution as described in the literature. An analysis of variance showed that the solution conductivity and the length of the cathode were the most important parameters in determining the total cathodic current capacity of the external surface. A semi-analytical equation was derived for the total current from a restricted geometry held at a constant potential at one end. The equation was able to reproduce all the model computation results both for the wetted external cathode and the crevice and give good explanation on the effects of physicochemical and kinetic parameters.

  16. Microbiological test results using three urine pretreatment regimes with 316L stainless steel

    NASA Technical Reports Server (NTRS)

    Huff, Timothy L.

    1993-01-01

    Three urine pretreatments, (1) Oxone (Dupont) and sulfuric acid, (2) sodium hypochlorite and sulfuric acid, (3) and ozone, were studied for their ability to reduce microbial levels in urine and minimize surface attachment to 316L stainless steel coupons. Urine samples inoculated with Bacillus insolitus and a filamentous mold, organisms previously recovered from the vapor compression distillation subsystem of NASA Space Station Freedom water recovery test were tested in glass corrosion cells containing base or weld metal coupons. Microbial levels, changes in pH, color, turbidity, and odor of the fluid were monitored over the course of the 21-day test. Specimen surfaces were examined by scanning electron microscopy at completion of the test for microbial attachment. Ozonated urine samples were less turbid and had lower microbial levels than controls or samples receiving other pretreatments. Base metal coupons receiving pretreatment were relatively free of attached bacteria. However, well-developed biofilms were found in the heat-affected regions of welded coupons receiving Oxone and hypochlorite pretreatments. Few bacteria were observed in the same regions of the ozone pretreatment sample.

  17. Structural analysis and intergranular corrosion tests of AISI 316L steel.

    PubMed

    Stonawská, Z; Svoboda, M; Sozańska, M; Krístková, M; Sojka, J; Dagbert, C; Hyspecká, L

    2006-10-01

    Pure AISI 316L steel is investigated after solution heat treatment (1050 degrees C/H(2)O) and structural sensitization (650 degrees C). Two quite different intergranular corrosion tests are used to determine the degree of structural sensitization due to the precipitation of secondary phases along the grain boundaries (mainly the M(23)C(6) and sigma-phase): the oxalic acid etch test and the electrochemical potentio-kinetic reactivation test. Generally, the dissolution of chromium-rich carbides (M(23)C(6)) is provoked by oxalic acid etch tests, whereas the chromium-depleted zones, in the vicinity of chromium-rich carbides (M(23)C(6)), are attacked by electrochemical potentio-kinetic reactivation tests. Both intergranular corrosion tests are used to determine the maximum degree of structural sensitization. Thus structural analysis by carbon replicas reveals the Laves phase, and both the M(23)C(6) and (Cr,Mo)(x)(Fe,Ni)(y) phases. The results of intergranular corrosion tests are related to the findings of the structural analysis.

  18. Spinodal decomposition in AISI 316L stainless steel via high-speed laser remelting

    NASA Astrophysics Data System (ADS)

    Chikarakara, Evans; Naher, Sumsun; Brabazon, Dermot

    2014-05-01

    A 1.5 kW CO2 pulsed laser was used to melt the surface of AISI 316L stainless steel with a view to enhancing the surface properties for engineering applications. A 90 μm laser beam spot size focused onto the surface was used to provide high irradiances (up to 23.56 MW/cm2) with low residence times (as low as 50 μs) in order to induce rapid surface melting and solidification. Variations in microstructure at different points within the laser treated region were investigated. From this processing refined lamellar and nodular microstructures were produced. These sets of unique microstructures were produced within the remelted region when the highest energy densities were selected in conjunction with the lowest residence times. The transformation from the typical austenitic structure to much finer unique lamellar and nodular structures was attributed to the high thermal gradients achieved using these selected laser processing parameters. These structures resulted in unique characteristics including elimination of cracks and a reduction of inclusions within the treated region. Grain structure reorientation between the bulk alloy and laser-treated region occurred due to the induced thermal gradients. This present article reports on microstructure forms resulting from the high-speed laser surface remelting and corresponding underlying kinetics.

  19. Welding of 316L Austenitic Stainless Steel with Activated Tungsten Inert Gas Process

    NASA Astrophysics Data System (ADS)

    Ahmadi, E.; Ebrahimi, A. R.

    2015-02-01

    The use of activating flux in TIG welding process is one of the most notable techniques which are developed recently. This technique, known as A-TIG welding, increases the penetration depth and improves the productivity of the TIG welding. In the present study, four oxide fluxes (SiO2, TiO2, Cr2O3, and CaO) were used to investigate the effect of activating flux on the depth/width ratio and mechanical property of 316L austenitic stainless steel. The effect of coating density of activating flux on the weld pool shape and oxygen content in the weld after the welding process was studied systematically. Experimental results indicated that the maximum depth/width ratio of stainless steel activated TIG weld was obtained when the coating density was 2.6, 1.3, 2, and 7.8 mg/cm2 for SiO2, TiO2, Cr2O3, and CaO, respectively. The certain range of oxygen content dissolved in the weld, led to a significant increase in the penetration capability of TIG welds. TIG welding with active fluxes can increase the delta-ferrite content and improves the mechanical strength of the welded joint.

  20. Galvanic deposition and characterization of brushite/hydroxyapatite coatings on 316L stainless steel.

    PubMed

    Blanda, Giuseppe; Brucato, Valerio; Pavia, Francesco Carfì; Greco, Silvia; Piazza, Salvatore; Sunseri, Carmelo; Inguanta, Rosalinda

    2016-07-01

    In this work, brushite and brushite/hydroxyapatite (BS, CaHPO4·H2O; HA, Ca10(PO4)6(OH)2) coatings were deposited on 316L stainless steel (316LSS) from a solution containing Ca(NO3)2·4H2O and NH4H2PO4 by a displacement reaction based on a galvanic contact, where zinc acts as sacrificial anode. Driving force for the cementation reaction arises from the difference in the electrochemical standard potentials of two different metallic materials (316LSS and Zn) immersed in an electrolyte, so forming a galvanic contact leading to the deposition of BS/HA on nobler metal. We found that temperature and deposition time affect coating features (morphology, structure, and composition). Deposits were characterized by means of several techniques. The morphology was investigated by scanning electron microscopy, the elemental composition was obtained by X-ray energy dispersive spectroscopy, whilst the structure was identified by Raman spectroscopy and X-ray diffraction. BS was deposited at all investigated temperatures covering the 316LSS surface. At low and moderate temperature, BS coatings were compact, uniform and with good crystalline degree. On BS layers, HA crystals were obtained at 50°C for all deposition times, while at 25°C, its presence was revealed only after long deposition time. Electrochemical studies show remarkable improvement in corrosion resistance. PMID:27127032

  1. Preliminary histological study of connective tissue response to Zinalco and stainless steel 316L implants after 120 days.

    PubMed

    Piña, C; Torres, C K; Guzmán, J

    1998-02-01

    Circular plates of Zinalco alloy (80 wt% Zn, 1.5 wt% Cu, 18.5 wt% Al) and stainless steel (SS) 316L were implanted in 12 female Wistar rats subcutaneously and intramuscularly to compare organism response, 120 days after implantation. The tissues surrounding the implants were analysed employing hematoxilin and eosin (H-E) and Gallego's trichromic techniques (GTT). Findings indicate that the reaction to Zinalco alloy was similar to the reaction to SS 316L. The Zn, Al and Cu concentrations in blood were measured, without evidence of any alteration due to implants. The presence and distribution of Zn, Al and Cu components of Zinalco alloy were detected in tissues by energy dispersive X-ray microanalysis.

  2. Result of International Round Robin Test on Young's Modulus Measurement of 304L and 316L Steels at Cryogenic Temperatures

    NASA Astrophysics Data System (ADS)

    Shibata, K.; Ogata, T.; Nyilas, A.; Walsh, R. P.; Millet, M. F.; Shindo, Y.; Fujii, H.; Ishio, K.; Nakajima, H.; Mitterbacher, H.; Toplosky, V. J.; Ohmiya, S.; Takano, K.; Gigante, P.

    2006-03-01

    Ogata et al. reported in 1996 results of international Round Robin tests on mechanical property measurement of several metals at cryogenic temperatures. Following the report, the standard deviation of Young's modulus of 316L steel is much larger than those of yield and tensile strengths, that is, 4.6 % of the mean value for Young's modulus, while 1.4 % and 1.6 % of the mean values for yield and for tensile strengths, respectively. Therefore, an international Round Robin test on Young's modulus of two austenitic stainless steels at cryogenic temperatures under the participation often institutes from four nations has been initiated within these two years. As a result, the ratios of standard deviation to the mean values are 4.2 % for 304L and 3.6 % for 316L. Such a drop in the standard deviation is attributable to the decrease in the number of institute owing to the application of single extensometer or direct strain gage technique.

  3. Structural, electrical and magnetic measurements on oxide layers grown on 316L exposed to liquid lead-bismuth eutectic

    NASA Astrophysics Data System (ADS)

    Hosemann, Peter; Hofer, Christian; Hlawacek, Gregor; Li, Ning; Maloy, Stuart A.; Teichert, Christian

    2012-02-01

    Fast reactors and spallation neutron sources may use lead-bismuth eutectic (LBE) as a coolant. Its physical, chemical, and irradiation properties make it a safe coolant compared to Na cooled designs. However, LBE is a corrosive medium for most steels and container materials. The present study was performed to evaluate the corrosion behavior of the austenitic steel 316L (in two different delivery states). Detailed atomic force microscopy, magnetic force microscopy, conductive atomic force microscopy, and scanning transmission electron microscopy analyses have been performed on the oxide layers to get a better understanding of the corrosion and oxidation mechanisms of austenitic and ferritic/martensitic stainless steel exposed to LBE. The oxide scale formed on the annealed 316L material consisted of multiple layers with different compositions, structures, and properties. The innermost oxide layer maintained the grain structure of what used to be the bulk steel material and shows two phases, while the outermost oxide layer possessed a columnar grain structure.

  4. Effect of forming technique BixSiyOz coatings obtained by sol- gel and supported on 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Bautista Ruiz, J.; Olaya Flórez, J.; Aperador, W.

    2016-02-01

    BixSiyOz type coatings via sol-gel synthesized from bismuth nitrate pentahydrate, and tetraethyl orthosilicate as precursors; glacial acetic acid and 2-ethoxyethanol as solvents, and ethanolamine as complexing. The coatings were supported on AISI 316L stainless steel substrate through dip-coating and spin-coating techniques. The study showed that the spin-coating technique is efficient than dip-coating because it allows more dense and homogeneous films.

  5. CORROSION STUDY FOR THE EFFLUENT TREATMENT FACILITY CHROME (VI) REDUCTANT SOLUTION USING 304 AND 316L STAINLESS STEEL

    SciTech Connect

    DUNCAN JB; WYRAS RB

    2007-10-08

    This report documents the laboratory testing and analyses as directed under the test plan, RPP PLAN-34065, and documented in laboratory notebooks HNF 2742 and HNF-N-473-1. The purpose of this study was to evaluate and compare the electrochemical corrosion and pitting susceptibility of the 304 and 316L stainless steel in the acidified reducing solution that will be contained in either the secondary waste receiving tank or concentrate tank.

  6. Creep deformation and fracture behavior of types 316 and 316L(N) stainless steels and their weld metals

    NASA Astrophysics Data System (ADS)

    Sasikala, G.; Mannan, S. L.; Mathew, M. D.; Rao, K. Bhanu

    2000-04-01

    The creep properties of a nuclear-grade type 316(L) stainless steel (SS) alloyed with nitrogen (316L(N) SS) and its weld metal were studied at 873 and 923 K in the range of applied stresses from 100 to 335 MPa. The results were compared with those obtained on a nuclear-grade type 316 SS, which is lean in nitrogen. The creep rupture lives of the weld metals were found to be lower than those of the respective base metals by a factor of 5 to 10. Both the base and weld metals of 316L(N) SS exhibited better resistance to creep deformation compared to their 316 SS counterparts at identical test conditions. A power-law relationship between the minimum creep rate and applied stress was found to be obeyed for both the base and weld metals. Both the weld metals generally exhibited lower rupture elongation than the respective base metals; however, at 873 K, the 316 SS base and weld metals had similar rupture elongation at identical applied stresses. Comparison of the rupture lives of the two steels to the ASME curves for the expected minimum stress to rupture for 316 SS base and weld metals showed that, for 316L(N) SS, the specifications for maximum allowable stresses based on data for 316 SS could prove overconservative. The influence of nitrogen on the creep deformation and fracture behavior, especially in terms of its modifying the precipitation kinetics, is discussed in light of the microstructural observations. In welds containing δ ferrite, the kinetics of its transformation and the nature of the transformation products control the deformation and fracture behavior. The influence of nitrogen on the δ ferrite transformation behavior and coarsening kinetics is also discussed, on the basis of extensive characterization by metallographic techniques.

  7. The effect of hydrogen peroxide on uranium oxide films on 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Wilbraham, Richard J.; Boxall, Colin; Goddard, David T.; Taylor, Robin J.; Woodbury, Simon E.

    2015-09-01

    For the first time the effect of hydrogen peroxide on the dissolution of electrodeposited uranium oxide films on 316L stainless steel planchets (acting as simulant uranium-contaminated metal surfaces) has been studied. Analysis of the H2O2-mediated film dissolution processes via open circuit potentiometry, alpha counting and SEM/EDX imaging has shown that in near-neutral solutions of pH 6.1 and at [H2O2] ⩽ 100 μmol dm-3 the electrodeposited uranium oxide layer is freely dissolving, the associated rate of film dissolution being significantly increased over leaching of similar films in pH 6.1 peroxide-free water. At H2O2 concentrations between 1 mmol dm-3 and 0.1 mol dm-3, formation of an insoluble studtite product layer occurs at the surface of the uranium oxide film. In analogy to corrosion processes on common metal substrates such as steel, the studtite layer effectively passivates the underlying uranium oxide layer against subsequent dissolution. Finally, at [H2O2] > 0.1 mol dm-3 the uranium oxide film, again in analogy to common corrosion processes, behaves as if in a transpassive state and begins to dissolve. This transition from passive to transpassive behaviour in the effect of peroxide concentration on UO2 films has not hitherto been observed or explored, either in terms of corrosion processes or otherwise. Through consideration of thermodynamic solubility product and complex formation constant data, we attribute the transition to the formation of soluble uranyl-peroxide complexes under mildly alkaline, high [H2O2] conditions - a conclusion that has implications for the design of both acid minimal, metal ion oxidant-free decontamination strategies with low secondary waste arisings, and single step processes for spent nuclear fuel dissolution such as the Carbonate-based Oxidative Leaching (COL) process.

  8. COMPUTATIONAL MODELING OF CATHODIC LIMITATIONS ON LOCALIZED CORROSION OF WETTED SS 316L, AT ROOM TEMPERATURE

    SciTech Connect

    F. Cui; F.J. Presuel-Moreno; R.G. Kelly

    2005-10-13

    The ability of a SS316L surface wetted with a thin electrolyte layer to serve as an effective cathode for an active localized corrosion site was studied computationally. The dependence of the total net cathodic current, I{sub net}, supplied at the repassivation potential E{sub rp} (of the anodic crevice) on relevant physical parameters including water layer thickness (WL), chloride concentration ([Cl{sup -}]) and length of cathode (Lc) were investigated using a three-level, full factorial design. The effects of kinetic parameters including the exchange current density (i{sub o,c}) and Tafel slope ({beta}{sub c}) of oxygen reduction, the anodic passive current density (i{sub p}) (on the cathodic surface), and E{sub rp} were studied as well using three-level full factorial designs of [Cl{sup -}] and Lc with a fixed WL of 25 {micro}m. The study found that all the three parameters WL, [Cl{sup -}] and Lc as well as the interactions of Lc x WL and Lc x [Cl{sup -}] had significant impact on I{sub net}. A five-factor regression equation was obtained which fits the computation results reasonably well, but demonstrated that interactions are more complicated than can be explained with a simple linear model. Significant effects on I{sub net} were found upon varying either i{sub o,c}, {beta}{sub c}, or E{sub rp}, whereas i{sub p} in the studied range was found to have little impact. It was observed that I{sub net} asymptotically approached maximum values (I{sub max}) when Lc increased to critical minimum values. I{sub max} can be used to determine the stability of coupled localized corrosion and the critical Lc provides important information for experimental design and corrosion protection.

  9. Effects of tritium on corrosion of welded type 316L stainless steel

    SciTech Connect

    Bellanger, G.

    1995-01-01

    An attempt was undertaken to investigate the localized corrosion susceptibility of tritiated oxidized weldments of Type 316L austenitic stainless steel made by the tungsten inert gas process. For this, the distribution of tritium at the surface was determined using a scintillation spectrophotometer. Depending on the values, the amounts of tritium are high enough to degrade the oxide. The polarization curves show a corrosion potential lower than that of a nontritiated weld. This means that tritiated welds have a less {open_quotes}noble{close_quotes}behavior. It is observed by voltammetry that the reduction of corrosion products always occurs during the cathodic scans, meaning less passivity for tritiated welds. Using electro-chemical impedance spectroscopy, the values of electron and ionic diffusion within the passive oxide were deduced. The tritiated oxide layer is thinner, and a higher concentration of electron carriers is observed; this indicates a less insulating oxide. The difference in electron carriers may come from ionization and breakdowns of the oxide layer by tritium and the energy released. The scanning electron microscopy (SEM) examinations show a complex microstructure of the tritiated surface that could be attributed both to the welding process and a severe degradation by tritium and energy released from the decay. It is well known that the ferrite is formed in the austenite during welding; this currently leads to corrosion of ferrite/austenite surface borders. This corrosion may be facilitated by the presence of tritium trapped at these surface borders, and the microcracks would nucleate leading to no cohesion of austenite. This mechanism is difficult to verify by SEM for stainless steel highly degraded by tritium and the energy released, but the visual examinations would appear to well support the results obtained by electrochemical methods, where the oxide is damaged. 28 refs., 15 figs., 3 tabs.

  10. Laser Surface Treatment of Stellite 6 Coating Deposited by HVOF on 316L Alloy

    NASA Astrophysics Data System (ADS)

    Shoja-Razavi, Reza

    2016-07-01

    This research aimed to study the effects of laser glazing treatment on microstructure, hardness, and oxidation behavior of Stellite 6 coating deposited by high velocity oxygen fuel (HVOF) spraying. The as-sprayed Stellite 6 coating (ST-HVOF) was subjected to single-pass and multiple-pass laser treatments to achieve the optimum glazing parameters. Microstructural characterizations were performed by x-ray diffractometry and field emission scanning electron microscopy equipped with energy-dispersive spectroscopy. Two-step optimization showed that laser treatment at the power of 200 W with a scan rate of 4 mm/s causes a surface layer with a thickness of 208 ± 32 µm to be remelted, while the underlying layers retain the original ST-HVOF coating structure. The obtained sample (ST-Glazing) exhibited a highly dense and uniform structure with an extremely low porosity of ~0.3%, much lower than that of ST-HVOF coating (2.3%). The average microhardness of ST-Glazing was measured to be 519 Hv0.3 indicating a 17% decrease compared to ST-HVOF (625 Hv0.3) due to the residual stress relief and dendrite coarsening from submicron size to ~3.4 µm after laser treatment. The lowest oxidation mass gain was obtained for ST-Glazing by 2 mg/cm2 after 8 cycles at 900 °C indicating 52 and 84% improvement in oxidation resistance in comparison to ST-HVOF and bare 316L steel substrates, respectively.

  11. Repassivation behavior of 316L stainless steel in borate buffer solution: Kinetics analysis of anodic dissolution and film formation

    NASA Astrophysics Data System (ADS)

    Xu, Haisong; Sun, Dongbai; Yu, Hongying

    2015-12-01

    The repassivation behavior of metals or alloys after oxide film damage determines the development of local corrosion and corrosion resistance. In this work, the repassivation kinetics of 316L stainless steel (316L SS) are investigated in borate buffer solution (pH 9.1) by using the abrading electrode technique. The current densities flowing from bare 316L SS surface are measured by potentiostatic method and analyzed to characterize repassivation kinetics. The initial stages of current decay (t < 500 ms) are discussed according to a film growth model, which describes the initial current transient should be divided into substrate dissolution current and passive film formation current based on Avrami kinetics. Then the two independent components are analyzed individually. The film formation rate and the thickness of film are compared in different applied potential. It is shown that anodic dissolution dominates the repassivation for a short time during the early times, and a higher applied potential will promote the anodic dissolution of metal. The film growth rate increases slightly with increasing in potential. Correspondingly, increase in applied potential from 0 VSCE to 0.8 VSCE results in thicker monolayer, which covers the whole bare surface at the time of θ = 1. The electric field strengths through the thin passive film could reach 3.97 × 106 V cm-1.

  12. Formation of Expanded Austenite on a Cold-Sprayed AISI 316L Coating by Low-Temperature Plasma Nitriding

    NASA Astrophysics Data System (ADS)

    Adachi, Shinichiro; Ueda, Nobuhiro

    2015-12-01

    Low-temperature plasma nitriding at temperatures below 450 °C is commonly applied to austenitic stainless steels to enhance wear resistance, while maintaining corrosion resistance, by forming expanded austenite (known as the S-phase). In this work, low-temperature plasma nitriding of cold-sprayed AISI 316L coatings was examined. A cold-spray technique was developed to produce metal coatings with less oxidation. However, the cold-sprayed AISI 316L coating obtained by use of nitrogen gas as propellant contained many interconnected pores and cracks, and was, consequently, unsuitable as an anticorrosive coating. Therefore, laser post-treatment was used to modify the coating and increase its density to similar to that of bulk steel. The anticorrosive performance of this coating on a carbon steel substrate in NaCl solution was substantially improved. Subsequent low-temperature plasma nitriding enhanced the wear resistance by two orders of magnitude. It is concluded that cold-sprayed AISI 316L coatings treated by laser post-treatment and subsequent low-temperature plasma nitriding could be used as protective coatings under severe wear and corrosion conditions.

  13. Electrochemical study of Type 304 and 316L stainless steels in simulated body fluids and cell cultures.

    PubMed

    Tang, Yee-Chin; Katsuma, Shoji; Fujimoto, Shinji; Hiromoto, Sachiko

    2006-11-01

    The electrochemical corrosion behaviour of Type 304 and 316L stainless steels was studied in Hanks' solution, Eagle's minimum essential medium (MEM), serum containing medium (MEM with 10% of fetal bovine serum) without cells, and serum containing medium with cells over a 1-week period. Polarization resistance measurements indicated that the stainless steels were resistant to Hanks' and MEM solutions. Type 304 was more susceptible to pitting corrosion than Type 316L in Hanks' and MEM solutions. The uniform corrosion resistance of stainless steels, determined by R(p), was lower in culturing medium than in Hanks' and MEM. The low corrosion resistance was due to surface passive film with less protective to reveal high anodic dissolution rate. When cells were present, the initial corrosion resistance was low, but gradually increased after 3 days, consistent with the trend of cell coverage. The presence of cells was found to suppress the cathodic reaction, that is, oxygen reduction, and increase the uniform corrosion resistance as a consequence. On the other hand, both Type 304 and 316L stainless steels became more susceptible to pitting corrosion when they were covered with cells.

  14. Nanohardness, corrosion and protein adsorption properties of CuAlO2 films deposited on 316L stainless steel for biomedical applications

    NASA Astrophysics Data System (ADS)

    Chang, Shih-Hang; Chen, Jian-Zhang; Hsiao, Sou-Hui; Lin, Guan-Wei

    2014-01-01

    This study preliminarily assesses the biomedical applications of CuAlO2 coatings according to nanoindentation, electrochemical, and protein adsorption tests. Nanoindentation results revealed that the surface hardness of 316L stainless steel increased markedly after coating with CuAlO2 films. Electrochemical tests of corrosion potential, breakdown potential, and corrosion current density showed that the corrosion resistance properties of 316L stainless steel are considerably improved by CuAlO2 coatings. Bicinchoninic acid (BCA) protein assay results revealed that the protein adsorption behavior of 316L stainless steel did not exhibit notable differences with or without CuAlO2 coatings. A CuAlO2 coating of 100 nm thickness improved the surface nanohardness and corrosion resistance ability of 316L stainless steel. CuAlO2 is a potential candidate for biomaterial coating applications, particularly for surface modification of fine, delicate implants.

  15. Effect of grain refinement and electrochemical nitridation on corrosion resistance of the 316L stainless steel for bipolar plates in PEMFCs environment

    NASA Astrophysics Data System (ADS)

    Jinlong, Lv; Tongxiang, Liang; Hongyun, Luo

    2015-10-01

    The stain-induced nanocrystalline α'-martensite was obtained by cryogenic cold rolling at liquid-nitrogen temperature for 316L stainless steel. The electrochemical results showed nanocrystalline 316L stainless steel deteriorated its corrosion resistance in a typical proton exchange membrane fuel cell environment compared with coarse grained one. However, comparing with electrochemically nitrided coarse grained stainless steel, electrochemically nitrided nanocrystalline stainless steel improved significantly corrosion resistance in the same environment, which was supported further by Mott-Shottky analysis. X-ray photoelectron spectroscopy analysis revealed that the nanocrystalline promoted the enrichment of nitrogen and chromium and inhibited form of NH3 on the surface, which could significantly improve the corrosion resistance of the 316L stainless steel. The present study showed that the electrochemically nitrided 316L stainless steel was more suitable for the bipolar plates in proton exchange membrane fuel cell environment than the untreated one, especially for nanocrystalline stainless steel.

  16. Study of the surface roughness evolution in fatigued 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Wang, Ye

    life. Scanning Whitelight Interferometric Microscope (SWLI) was applied to quantitatively study the surface roughness evolution of polycrystalline 316L stainless steel fatigue specimen. We demonstrated that the surface roughness increased with fatigue cycles during the entire fatigue process. In addition, we discovered that surface roughness increases at early fatigue stage were contributed by slip band formation while surface roughness increases at later-stage fatigue were due to the out-of-plane displacement of adjacent grains. Crack initiation and development has also been identified.

  17. Effects of AISI 316L corrosion products in in vitro bone formation.

    PubMed

    Morais, S; Sousa, J P; Fernandes, M H; Carvalho, G S; de Bruijn, J D; van Blitterswijk, C A

    1998-06-01

    Rat bone marrow cells were cultured in experimental conditions that favour the proliferation and differentiation of osteoblastic cells (i.e., 2.52 x 10(-4) mol l(-1) ascorbic acid, 10(-2) mol l(-1) beta-glycerophosphate and 10(-8) mol l(-1) dexamethasone) in the absence and in the presence of stainless-steel corrosion products, for a period of 18 days. An AISI 316L stainless-steel slurry (SS) was obtained by electrochemical means and the concentrations of the major metal ions, determined by atomic absorption spectrometry, were 8.78 x 10(-3) mol l(-1) of Fe, 4.31 x 10(-3) mol l(-1) of Cr and 2.56 x 10(-3) mol l(-1) of Ni. Bone marrow cells were exposed to 0.01, 0.1 and 1% of the SS and at the end of the incubation period, control and treated cultures were evaluated by histochemical assays for the identification of the presence of alkaline phosphatase and also calcium and phosphate deposition. Cultures were further observed by scanning electron microscopy. Levels of total and ionised calcium and phosphorus in the culture media collected from control and metal exposed cell cultures were also quantified. Histochemical staining showed that control cultures presented a strong reaction for the presence of alkaline phosphatase and exhibited formation of calcium and phosphates deposits. The presence of 0.01% SS caused no detectable biological effects in these cultures, 0.1% SS impaired osteoblastic behaviour and, 1% SS resulted in cell death. In the absence of bone cells, levels of total and ionised calcium and phosphorus in the control and metal added culture medium were similar throughout the incubation period. A significant decrease in the levels of ionised calcium and phosphorus were observed in the culture medium of control cultures and also in cultures exposed to 0.01% SS after two weeks of incubation, an event related with the formation of mineral calcium phosphate deposits in these cultures. In cultures grown in the presence of 0.1 and 1% SS corrosion products

  18. A mechanism for the enhanced attachment and proliferation of fibroblasts on anodized 316L stainless steel with nano-pit arrays.

    PubMed

    Ni, Siyu; Sun, Linlin; Ercan, Batur; Liu, Luting; Ziemer, Katherine; Webster, Thomas J

    2014-08-01

    In this study, 316L stainless steel with tunable nanometer pit sizes (0, 25, 50, and 60 nm) were fabricated by an anodization procedure in an ethylene glycol electrolyte solution containing 5 vol % perchloric acid. The surface morphology and elemental composition of the 316L stainless steel were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The nano-pit arrays on all of the 316L stainless steel samples were in a regular arrangement. The surface properties of the 316L stainless steel nano-pit surface showed improved wettability properties as compared with the untreated 316L stainless steel, as demonstrated by the lower contact angles which dropped from 83.0° to 28.6 to 45.4°. The anodized 316L stainless steel surfaces with 50 nm and 60 nm diameter pits were also more rough at the nanoscale. According to MTT assays, compared with unanodized (that is, nano-smooth) surfaces, the 50 and 60 nm diameter nano-pit surfaces dramatically enhanced initial human dermal fibroblast attachment and growth for up to 3 days in culture. Mechanistically, this study also provided the first evidence of greater select protein adsorption (specifically, vitronectin and fibronectin which have been shown to enhance fibroblast adhesion) on the anodized 316L stainless steel compared with unanodized stainless steel. Such nano-pit surfaces can be designed to support fibroblast growth and, thus, improve the use of 316L stainless steel for various implant applications (such as for enhanced skin healing for amputee devices and for percutaneous implants).

  19. Interfacial characterization of SLM parts in multi-material processing: Metallurgical diffusion between 316L stainless steel and C18400 copper alloy

    SciTech Connect

    Liu, Z.H. Zhang, D.Q. Sing, S.L. Chua, C.K. Loh, L.E.

    2014-08-15

    Multi-material processing in selective laser melting using a novel approach, by the separation of two different materials within a single dispensing coating system was investigated. 316L stainless steel and UNS C18400 Cu alloy multi-material samples were produced using selective laser melting and their interfacial characteristics were analyzed using focused ion beam, scanning electron microscopy, energy dispersive spectroscopy and electron back scattered diffraction techniques. A substantial amount of Fe and Cu element diffusion was observed at the bond interface suggesting good metallurgical bonding. Quantitative evidence of good bonding at the interface was also obtained from the tensile tests where the fracture was initiated at the copper region. Nevertheless, the tensile strength of steel/Cu SLM parts was evaluated to be 310 ± 18 MPa and the variation in microhardness values was found to be gradual along the bonding interface from the steel region (256 ± 7 HV{sub 0.1}) to the copper region (72 ± 3 HV{sub 0.1}). - Highlights: • Multi-material processing was successfully implemented and demonstrated in SLM. • Bi-metallic laminates of steel/Cu were successfully produced with the SLM process. • A substantial amount of Fe and Cu diffusion was observed at the bond interface. • Good metallurgical bonding was obtained at the interface of the steel/Cu laminates. • Highly refined microstructure was obtained due to rapid solidification in SLM.

  20. One-dimensional migration of interstitial clusters in SUS316L and its model alloys at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Satoh, Y.; Abe, H.; Matsukawa, Y.; Matsunaga, T.; Kano, S.; Arai, S.; Yamamoto, Y.; Tanaka, N.

    2015-05-01

    For self-interstitial atom (SIA) clusters in various concentrated alloys, one-dimensional (1D) migration is induced by electron irradiation around 300 K. But at elevated temperatures, the 1D migration frequency decreases to less than one-tenth of that around 300 K in iron-based bcc alloys. In this study, we examined mechanisms of 1D migration at elevated temperatures using in situ observation of SUS316L and its model alloys with high-voltage electron microscopy. First, for elevated temperatures, we examined the effects of annealing and short-term electron irradiation of SIA clusters on their subsequent 1D migration. In annealed SUS316L, 1D migration was suppressed and then recovered by prolonged irradiation at 300 K. In high-purity model alloy Fe-18Cr-13Ni, annealing or irradiation had no effect. Addition of carbon or oxygen to the model alloy suppressed 1D migration after annealing. Manganese and silicon did not suppress 1D migration after annealing but after short-term electron irradiation. The suppression was attributable to the pinning of SIA clusters by segregated solute elements, and the recovery was to the dissolution of the segregation by interatomic mixing under electron irradiation. Next, we examined 1D migration of SIA clusters in SUS316L under continuous electron irradiation at elevated temperatures. The 1D migration frequency at 673 K was proportional to the irradiation intensity. It was as high as half of that at 300 K. We proposed that 1D migration is controlled by the competition of two effects: induction of 1D migration by interatomic mixing and suppression by solute segregation.

  1. Comparative study of mechanical properties of 316L stainless steel between traditional production methods and selective laser melting

    NASA Astrophysics Data System (ADS)

    Lackey, Alton Dale

    Additive manufacturing, also known as 3D printing, is a technology which has recently seen expanding use, as well as expansion of the materials and methods able to be used. This thesis looks at the comparison of mechanical properties of 316L stainless steel manufactured by both traditional methods and selective laser melting found by tensile testing. The traditional method used here involved cold rolled 316L steel being machined to the desired part geometry. Selective laser melting used additive manufacturing to produce the parts from powdered 316L stainless steel, doing so in two different build orientations, flat and on edge with regards to the build plate. Solid test specimens, as well as specimens containing a circular stress concentration in the center of the parts, were manufactured and tensile tested. The tensile tests of the specimens were used to find the mechanical properties of the material; including yield strength, ultimate tensile strength (UTS), and Young's modulus of elasticity; where statistical analyses were performed to determine if the different manufacturing processes caused significant differences in the mechanical properties of the material. These analysis consisting of f-tests, to test for variance, and t-test, testing for significant difference of means. Through this study it was found that there were statistically significant differences existing between the mechanical properties of selective laser melting, and its orientations, and cold roll forming of production of parts. Even with a statistical difference, it was found that the results were reasonably close between flat oriented SLM parts and purchased parts. So it can be concluded that, with regards to strength, SLM methods produce parts similar to traditional production methods.

  2. Study of scale formation on AISI 316L in simulated solid oxide fuel cell bi-polar environments

    SciTech Connect

    Ziomek-Moroz, M.; Covino, Bernard S., Jr.; Cramer, Stephen D.; Holcomb, Gordon R.; Bullard, Sophie J.; Singh , P.; Windisch, C.F., Jr.

    2004-01-01

    Significant progress made towards reducing the operating temperature of solid oxide fuel cells (SOFC) from {approx}1000 C to {approx}600 C is expected to permit the use of metallic materials with substantial cost reduction. One of the components in a SOFC stack to be made of metallic materials is a bipolar separator, also called an interconnect. It provides electrical connection between individual cells and serves as a gas separator to prevent mixing of the fuel and air. At operating temperature, the material selected for interconnects should possess good chemical and mechanical stability in complex fuel and oxidant gaseous environments, good electrical conductivity, and a coefficient of thermal expansion (CTE) that matches that of the cathode, anode, and electrolyte components. Cr2O3 scale-forming alloys appear to be the most promising candidates. There appears to be a mechanism whereby the environment on the fuel side of a stainless steel interconnect changes the corrosion behavior of the metal on the air side. The corrosion behavior of 316L stainless steel simultaneously exposed to air on one side and H2+3%H2O on the other at 907 K was studied using X-ray diffraction (XRD) and Raman spectroscopy. The electrical property of the investigated material was determined in terms of area-specific resistance (ASR). The chemical and electrical properties of 316L exposed to a dual environment of air/ (H2+H2O) were compared to those of 316L exposed to a single environment of air/air.

  3. Crack growth behavior of warm-rolled 316L austenitic stainless steel in high-temperature hydrogenated water

    NASA Astrophysics Data System (ADS)

    Choi, Kyoung Joon; Yoo, Seung Chang; Jin, Hyung-Ha; Kwon, Junhyun; Choi, Min-Jae; Hwang, Seong Sik; Kim, Ji Hyun

    2016-08-01

    To investigate the effects of warm rolling on the crack growth of 316L austenitic stainless steel, the crack growth rate was measured and the oxide structure was characterized in high-temperature hydrogenated water. The warm-rolled specimens showed a higher crack growth rate compared to the as-received specimens because the slip bands and dislocations produced during warm rolling served as paths for corrosion and cracking. The crack growth rate increased with the dissolved hydrogen concentration. This may be attributed to the decrease in performance and stability of the protective oxide layer formed on the surface of stainless steel in high-temperature water.

  4. Surface modification of 316L stainless steel with magnetron sputtered TiN/VN nanoscale multilayers for bio implant applications.

    PubMed

    Subramanian, B; Ananthakumar, R; Kobayashi, Akira; Jayachandran, M

    2012-02-01

    Nanoscale multilayered TiN/VN coatings were developed by reactive dc magnetron sputtering on 316L stainless steel substrates. The coatings showed a polycrystalline cubic structure with (111) preferential growth. XPS analysis indicated the presence of peaks corresponding to Ti2p, V2p, N1s, O1s, and C1s. Raman spectra exhibited the characteristic peaks in the acoustic range of 160-320 cm(-1) and in the optic range between 480 and 695 cm(-1). Columnar structure of the coatings was observed from TEM analysis. The number of adherent platelets on the surface of the TiN/VN multilayer, VN, TiN single layer coating exhibit fewer aggregation and pseudopodium than on substrates. The wear resistance of the multilayer coatings increases obviously as a result of their high hardness. Tafel plots in simulated bodily fluid showed lower corrosion rate for the TiN/VN nanoscale multilayer coatings compared to single layer and bare 316L SS substrate.

  5. Cross-sectional transmission electron microscopy of ultra-fine wires of AISI 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Wang, H. S.; Wei, R. C.; Huang, C. Y.; Yang, J. R.

    2006-01-01

    Starting with 190?µm diameter wire of 316L stainless steel, ultra-thin wire just 8?µm in diameter has been made and characterized. There was no intermediate heat treatment used in the process of drawing, and the amount of true stain was about 6.3. A specimen preparation method for the cross-sectional transmission electron microscopy (TEM) of ultra-fine wires of 316L stainless steel has been developed. The ultra-fine wire was sandwiched between silicon chips and the bonded assembly then sliced to produce longitudinal and transverse sections of the wire in a form suitable for further processing into electron transparent samples. TEM reveals that the heavily deformed wire consists of nanoscale fine elongated structures along the drawing direction. The diffraction patterns indicate that a substantial amount of austenite has transformed into martensite. The TEM dark field images show nanosized patches of martensite distributed among the debris of austenite along the drawing direction. The evidence strongly suggests that severe deformation leads to mechanical stabilization of austenite against the growth of martensite.

  6. Effect of Filler Metals on the Weldability and Mechanical Properties of Multi-pass PCGTA Weldments of AISI 316L

    NASA Astrophysics Data System (ADS)

    Devendranath Ramkumar, K.; Maruthi Mohan Reddy, P.; Raja Arjun, B.; Choudhary, Ayush; Srivastava, Anubhav; Arivazhagan, N.

    2015-04-01

    The influence of filler metals on the microstructure, mechanical properties, and corrosion behavior of AISI 316L welds was investigated. Pulsed current gas tungsten arc welding was employed to join the AISI 316L plates using two different fillers ER2553 and ERNiCr-3. Microstructures studies showed the presence of different forms of austenite on employing ER2553 filler and formation of migrated grain boundaries at the weld zone while using ERNiCr-3 filler. Tensile studies corroborated that the tensile strength was greater for the weldments employing ER2553 filler. Charpy V-notch studies ascertained that the impact toughness was greater for ER2553 weldments as compared to the parent metal. Potentiodynamic polarization curves clearly inferred that the weld zone of ER2553 exhibited better corrosion resistance among the various coupons tested. It was concluded from the study that ER2553 exhibited better mechanical and corrosion properties and could be adopted to achieve optimal properties compared to over-alloyed filler.

  7. Liquid Metal Corrosion of 316L Stainless Steel, 410 Stainless Steel, and 1015 Carbon Steel in a Molten Zinc Bath

    NASA Astrophysics Data System (ADS)

    Xu, Jing; Bright, Mark A.; Liu, Xingbo; Barbero, Ever

    2007-11-01

    Corrosion tests of 1015 low-carbon steel and two stainless steels (410 and 316L) were conducted in a pure zinc bath (99.98 wt pct Zn) in order to better understand the reaction mechanisms that occur during the degradation of submerged hardware at industrial general (batch) galvanizing operations. Through this testing, it was found that, in general, 316L stainless steel showed the best dissolution resistance among these three alloys, while 1015 carbon steel provided a lower solubility than 410 stainless steel. Investigating the failure mechanisms, both metallurgical composition and lattice structure played important roles in the molten metal corrosion behaviors of these alloys. High contents of nickel combined with the influence of chromium improved the resistance to molten zinc corrosion. Moreover, a face-centered-cubic (fcc) structure was more corrosion resistant than body-centered-cubic (bcc) possibly due to the compactness of the atomic structure. Analogously, the body-centered-tetragonal (bct) martensite lattice structure possessed enhanced susceptibility to zinc corrosion as a result of the greater atomic spacing and high strain energy. Finally, an increased bath temperature played an important role in molten metal corrosion by accelerating the dissolution process and changing the nature of intermetallic layers.

  8. Corrosion-erosion test of SS316L grain boundary engineering material (GBEM) in lead bismuth flowing loop

    NASA Astrophysics Data System (ADS)

    Saito, Shigeru; Kikuchi, Kenji; Hamaguchi, Dai; Tezuka, Masao; Miyagi, Masanori; Kokawa, Hiroyuki; Watanabe, Seiichi

    2012-12-01

    To evaluate the lifetime of structural materials utilized in a spallation neutron source, corrosion tests in lead-bismuth eutectic (LBE) have been done at JAEA. Austenitic steels are preferable as the structural material for ADS. However, previous studies have revealed that austenitic steel SS316 shows severe corrosion-erosion in LBE because of LBE penetration through grain boundaries and separation of grains. So it was considered that GBE (grain-boundary engineered) materials may be effective to improve the corrosion resistance of austenitic steels in LBE. In this study, the results of corrosion tests on austenitic steel SS316L-BM (base metal) and SS316L-GBEM (grain-boundary-engineered material) under flowing LBE conditions will be reported. The corrosion test was performed using the JAEA lead-bismuth material corrosion loop (JLBL-1). The experimental conditions were as follows: The high and low temperature parts of the loop were 450 °C and 350 °C, respectively. The flow velocity at the test specimens was about 0.7 m/s. The oxygen concentration in LBE was not controlled and was estimated to have been very low. After the 3600 h of operation, macroscopic, SEM, and SIM observations and EDX analysis were carried out. The results showed that the corrosion depth and LBE penetration through the grain boundaries of the 316SS-GBEM were smaller than those of the 316SS-BM.

  9. Evaluation of in-pile and out-of-pile stress relaxation in 316L stainless steel under uniaxial loading

    NASA Astrophysics Data System (ADS)

    Kaji, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi; Kikuchi, Masahiko; Kita, Satoshi; Yonekawa, Minoru; Nakano, Junichi; Tsuji, Hirokazu; Nakajima, Hajime

    2002-12-01

    Stress relaxation of tensile type specimens under fast neutron irradiation at 288 °C has been studied for 316L stainless steel (SS) in the Japan Materials Testing Reactor. In-pile stress-relaxation tests were carried out at fast neutron fluence levels of 1.3×10 24, 5.5×10 24 and 1.5×10 25 n/m 2 ( E>1 MeV). These tests were carried out at the applied total strain levels of 0.06%, 0.1%, 0.3% and 0.75%. In order to evaluate the thermal stress-relaxation behavior and to distinguish it from the irradiation induced stress-relaxation behavior, out-of-pile stress-relaxation tests were also performed at 288 °C in air using an electric furnace. This paper describes results of in-pile and out-of-pile stress-relaxation tests on 316L SS tensile specimens. These results are compared with the literature data by Foster et al. [J. Nucl. Mater. 252 (1998) 89] which were mainly obtained from bend beam specimens. Moreover, these experimental results are compared with analytical results obtained using Nagakawa's model [J. Nucl. Mater. 212-215 (1994) 541].

  10. Improving the Adhesion Resistance of the Boride Coatings to AISI 316L Steel Substrate by Diffusion Annealing

    NASA Astrophysics Data System (ADS)

    Campos-Silva, I.; Bernabé-Molina, S.; Bravo-Bárcenas, D.; Martínez-Trinidad, J.; Rodríguez-Castro, G.; Meneses-Amador, A.

    2016-07-01

    In this study, new results about the practical adhesion resistance of boride coating/substrate system formed at the surface of AISI 316 L steel and improved by means of a diffusion annealing process are presented. First, the boriding of AISI 316 L steel was performed by the powder-pack method at 1173 K with different exposure times (4-8 h). The diffusion annealing process was conducted on the borided steels at 1273 K with 2 h of exposure using a diluent atmosphere of boron powder mixture. The mechanical behavior of the boride coating/substrate system developed by both treatments was established using Vickers and Berkovich tests along the depth of the boride coatings, respectively. Finally, for the entire set of experimental conditions, the scratch tests were performed with a continuously increasing normal force, in which the practical adhesion resistance of the boride coating/substrate system was represented by the critical load. The failure mechanisms developed over the surface of the scratch tracks were analyzed; the FeB-Fe2B/substrate system exhibited an adhesive mode, while the Fe2B/substrate system obtained by the diffusion annealing process showed predominantly a cohesive failure mode.

  11. Hydrophilic property of 316L stainless steel after treatment by atmospheric pressure corona streamer plasma using surface-sensitive analyses

    NASA Astrophysics Data System (ADS)

    Al-Hamarneh, Ibrahim; Pedrow, Patrick; Eskhan, Asma; Abu-Lail, Nehal

    2012-10-01

    Surgical-grade 316L stainless steel (SS 316L) had its surface hydrophilic property enhanced by processing in a corona streamer plasma reactor using O2 gas mixed with Ar at atmospheric pressure. Reactor excitation was 60 Hz ac high-voltage (0-10 kVRMS) applied to a multi-needle-to-grounded screen electrode configuration. The treated surface was characterized with a contact angle tester. Surface free energy (SFE) for the treated stainless steel increased measurably compared to the untreated surface. The Ar-O2 plasma was more effective in enhancing the SFE than Ar-only plasma. Optimum conditions for the plasma treatment system used in this study were obtained. X-ray photoelectron spectroscopy (XPS) characterization of the chemical composition of the treated surfaces confirms the existence of new oxygen-containing functional groups contributing to the change in the hydrophilic nature of the surface. These new functional groups were generated by surface reactions caused by reactive oxidation of substrate species. Atomic force microscopy (AFM) images were generated to investigate morphological and roughness changes on the plasma treated surfaces. The aging effect in air after treatment was also studied.

  12. Complexation- and ligand-induced metal release from 316L particles: importance of particle size and crystallographic structure.

    PubMed

    Hedberg, Yolanda; Hedberg, Jonas; Liu, Yi; Wallinder, Inger Odnevall

    2011-12-01

    Iron, chromium, nickel, and manganese released from gas-atomized AISI 316L stainless steel powders (sized <45 and <4 μm) were investigated in artificial lysosomal fluid (ALF, pH 4.5) and in solutions of its individual inorganic and organic components to determine its most aggressive component, elucidate synergistic effects, and assess release mechanisms, in dependence of surface changes using atomic absorption spectroscopy, Raman, XPS, and voltammetry. Complexation is the main reason for metal release from 316L particles immersed in ALF. Iron was mainly released, while manganese was preferentially released as a consequence of the reduction of manganese oxide on the surface. These processes resulted in highly complexing media in a partial oxidation of trivalent chromium to hexavalent chromium on the surface. The extent of metal release was partially controlled by surface properties (e.g., availability of elements on the surface and structure of the outermost surface) and partially by the complexation capacity of the different metals with the complexing agents of the different media. In general, compared to the coarse powder (<45 μm), the fine (<4 μm) powder displayed significantly higher released amounts of metals per surface area, increased with increased solution complexation capacity, while less amounts of metals were released into non-complexing solutions. Due to the ferritic structure of lower solubility for nickel of the fine powder, more nickel was released into all solutions compared with the coarser powder.

  13. Improving the Adhesion Resistance of the Boride Coatings to AISI 316L Steel Substrate by Diffusion Annealing

    NASA Astrophysics Data System (ADS)

    Campos-Silva, I.; Bernabé-Molina, S.; Bravo-Bárcenas, D.; Martínez-Trinidad, J.; Rodríguez-Castro, G.; Meneses-Amador, A.

    2016-09-01

    In this study, new results about the practical adhesion resistance of boride coating/substrate system formed at the surface of AISI 316 L steel and improved by means of a diffusion annealing process are presented. First, the boriding of AISI 316 L steel was performed by the powder-pack method at 1173 K with different exposure times (4-8 h). The diffusion annealing process was conducted on the borided steels at 1273 K with 2 h of exposure using a diluent atmosphere of boron powder mixture. The mechanical behavior of the boride coating/substrate system developed by both treatments was established using Vickers and Berkovich tests along the depth of the boride coatings, respectively. Finally, for the entire set of experimental conditions, the scratch tests were performed with a continuously increasing normal force, in which the practical adhesion resistance of the boride coating/substrate system was represented by the critical load. The failure mechanisms developed over the surface of the scratch tracks were analyzed; the FeB-Fe2B/substrate system exhibited an adhesive mode, while the Fe2B/substrate system obtained by the diffusion annealing process showed predominantly a cohesive failure mode.

  14. Effect of Zr, Nb and Ti addition on injection molded 316L stainless steel for bio-applications: Mechanical, electrochemical and biocompatibility properties.

    PubMed

    Gulsoy, H Ozkan; Pazarlioglu, Serdar; Gulsoy, Nagihan; Gundede, Busra; Mutlu, Ozal

    2015-11-01

    The research investigated the effect of Zr, Nb and Ti additions on mechanical, electrochemical properties and biocompatibility of injection molded 316L stainless steel. Addition of elemental powder is promoted to get high performance of sintered 316L stainless steels. The amount of additive powder plays a role in determining the sintered microstructure and all properties. In this study, 316L stainless steel powders used with the elemental Zr, Nb and Ti powders. A feedstock containing 62.5 wt% powders loading was molded at different injection molded temperature. The binders were completely removed from molded components by solvent and thermal debinding at different temperatures. The debinded samples were sintered at 1350°C for 60 min. Mechanical, electrochemical property and biocompatibility of the sintered samples were performed mechanical, electrochemical, SBF immersion tests and cell culture experiments. Results of study showed that sintered 316L and 316L with additives samples exhibited high corrosion properties and biocompatibility in a physiological environment. PMID:26275484

  15. On the corrosion resistance of AISI 316L-type stainless steel coated with manganese and annealed with flow of oxygen

    NASA Astrophysics Data System (ADS)

    Savaloni, Hadi; Agha-Taheri, Ensieh; Abdi, Fateme

    2016-06-01

    AISI 316L-type stainless steel was coated with 300-nm-thick Mn thin films and post-annealed at 673 K with a constant flow of oxygen (250 cm3/min). The films crystallographic and morphological structures were analyzed using X-ray diffraction (XRD) and atomic force microscopy (AFM) before corrosion test and scanning electron microscopy (SEM) after corrosion test. Corrosion behavior of the samples in 0.3, 0.5 and 0.6 M NaCl solutions was investigated by means of potentiodynamic and electrochemical impedance spectroscopy (EIS) techniques. Results showed that the corrosion inhibition of annealed Mn/SS316L in all NaCl solutions with different concentrations is higher than that of bare SS316L. A correlation is achieved between the structural variation of the films with the potentiodynamic and EIS corrosion results.

  16. The Effect of Constant and Pulsed Current Gas Tungsten Arc Welding on Joint Properties of 2205 Duplex Stainless Steel to 316L Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Neissi, R.; Shamanian, M.; Hajihashemi, M.

    2016-05-01

    In this study, dissimilar 316L austenitic stainless steel/2205 duplex stainless steel (DSS) joints were fabricated by constant and pulsed current gas tungsten arc welding process using ER2209 DSS as a filler metal. Microstructures and joint properties were characterized using optical and electron scanning microscopy, tensile, Charpy V-notch impact and micro-hardness tests, and cyclic polarization measurements. Microstructural observations confirmed the presence of chromium nitride and delta ferrite in the heat-affected zone of DSS and 316L, respectively. In addition, there was some deviation in the austenite/ferrite ratio of the surface welding pass in comparison to the root welding pass. Besides having lower pitting potential, welded joints produced by constant current gas tungsten arc welding process, consisted of some brittle sigma phase precipitates, which resulted in some impact energy reduction. The tensile tests showed high tensile strength for the weld joints in which all the specimens were broken in 316L base metal.

  17. Effects of Ti-C:H coating and plasma nitriding treatment on tribological, electrochemical, and biocompatibility properties of AISI 316L.

    PubMed

    Kao, W H; Su, Y L; Horng, J H; Zhang, K X

    2016-08-01

    Ti-C:H coatings were deposited on original, nitrided, and polished-nitrided AISI 316L stainless steel substrates using a closed field unbalanced magnetron sputtering system. Sliding friction wear tests were performed in 0.89 wt.% NaCl solution under a load of 30 N against AISI 316L stainless steel, Si3N4, and Ti6Al4V balls, respectively. The electrochemical properties of the various specimens were investigated by means of corrosion tests performed in 0.89 wt.% NaCl solution at room temperature. Finally, the biocompatibility properties of the specimens were investigated by performing cell culturing experiments using purified mouse leukemic monocyte macrophage cells (Raw264.7). In general, the results showed that plasma nitriding followed by Ti-C:H coating deposition provides an effective means of improving the wear resistance, anti-corrosion properties, and biocompatibility performance of AISI 316L stainless steel.

  18. Effect of relative humidity in high temperature oxidation of ceria nanoparticles coating on 316L austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Giraldez Pizarro, Luis Miguel

    A solution of 20 wt. % colloidal dispersion of Cerium Oxide (CeO2) in 2.5% of acetic acid, was used for depositing a coating film on an austenitic stainless steel 316L. Cerium compounds have been distinguished as potential corrosion inhibitors in coatings over several alloys. The oxidation behavior of the cerium oxide coating on 316L austenitic stainless steel alloy was evaluated in dry and humid environments, the weight changes (W/A) was monitored as a function of time using a custom built Thermogravimetrical Analysis (TGA) instrument at temperatures of 750°C, 800°C and 850°C, and different relative humidity levels (0%, 10% and 20%) respectively. The parabolic oxidation rate and activation energy is calculated experimentally for each relative humidity level. A measurement of the effective diameter size of the ceria nanoparticles was performed using a Light Scattering technique. A characterization of the film morphology and thickness before the oxidation was executed using Atomic Force Microscopy (AFM). Microstructure and chemical composition of the oxidized coated substrates were analyzed using Scanning Electronic Microscopy (SEM) with energy dispersive spectroscopy (EDS). X-Ray Diffractometer (XRD) was used to characterize oxides formed in the surface upon isothermal treatment. A comparison of activation energy values obtained to identify the influence of relative humidity in the oxidation process at high temperature was conducted. Cerium oxides coating may prevent crevice corrosion and increase pitting resistance of 316L relative to the uncoated substrate at high temperatures and different levels of relative humidity acting as a protective oxidation barrier. The calculated parabolic rate constants, kp, at the experimental temperatures tend to increase as a function of humidity levels. The activation energy tends to increase proportionally to higher level of humidity exposures. At 0% relative humidity a value of 319.29 KJ/mol of activation energy is being

  19. Diffusion Bonding Behavior and Characterization of Joints Made Between 316L Stainless Steel Alloy and AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Elthalabawy, Waled Mohamed

    The 316L austenitic stainless steel and AZ31 magnesium alloy have physical and mechanical properties which makes these alloys suitable in a number of high technology based industries such as the aerospace and automotive sectors. However, for these alloys to be used in engineering applications, components must be fabricated and joined successfully. The differences in the physical and metallurgical properties between these two alloys prevents the use of conventional fusion welding processes commonly employed in aerospace and transport industry. Therefore, alternative techniques need to be developed and diffusion bonding technology is a process that has considerable potential to join these two dissimilar alloys. In this research work both solid-state and transient liquid phase (TLP) bonding processes were applied. The solid-state bonding of 316L steel to AZ31 magnesium alloy was possible at a bonding temperature of 550°C for 120 minutes using a pressure of 1.3 MPa. The interface characterization of the joint showed a thin intermetallic zone rich in Fe-Al was responsible for providing a metallurgical bond. However, low joint shear strengths were recorded and this was attributed to the poor surface to surface contact. The macro-deformation of the AZ31 alloy prevented the use of higher bonding pressures and longer bonding times. In order to overcome these problems, the TLP bonding process was implemented using pure Cu and Ni foils as interlayers which produced a eutectic phase at the bonding temperature. This research identified the bonding mechanism through microstructural and differential scanning calorimetry investigations. The microstructural characterization of the TLP joints identified intermetallics which became concentrated along the 316L steel/AZ31 bond interface due to the "pushing effect" of the solid/liquid interface during isothermal solidification stage of bonding. The size and concentration of the intermetallics had a noticeable effect on the final joint

  20. Localized corrosion of 316L stainless steel with SiO2-CaO films obtained by means of sol-gel treatment.

    PubMed

    Vallet-Regí, M; Izquierdo-Barba, I; Gil, F J

    2003-11-01

    Sol-gel films on austenitic stainless steel (AISI 316L) polished wafer were prepared from sono-sols obtained from tetraethylorthosilane and hydrated calcium nitrate. However, pitting was observed in different places on the stainless steel surfaces. The corrosion resistance was evaluated by the polarization resistance in simulated body fluid environment at 37 degrees C. The critical current density, the passive current density, the corrosion potential, and the critical pitting potential were studied. The austenitic stainless steel 316L treated presents important electrochemical corrosion and consequently its application as endosseous implants is not possible. PMID:14566812

  1. Microstructural examination of the effect of surface machining on stress corrosion cracking in core shroud made of 316L

    SciTech Connect

    Sueishi, Y.; Kohyama, A.; Narui, M.; Asano, K.

    2006-07-01

    Cracks exhibited on the hardened surface region of the boiling water reactor (BWR) core shroud made of 316L were examined. The sample was removed from the circumference ring of a commercial power plant after about 9 years in service. On the surface with mechanical milling followed by grinding during the manufacturing process, micro-crack was found to propagate nearly perpendicular to the grinding direction. Cross-sectional transmission electron microscopy (TEM) observation of the micro-crack indicates that the crack has been initiated along the boundary of [111[<112> type deformation twins and the shear bands in Goss position [110]<001>. Along the crack wall, the Cr-Fe spinel and the grained magnetite were identified in inner and outer layer of the oxide thin film, respectively. The results suggest one potential mechanism of the cracking that the heavily deformed structure by surface machining is the origin or the factor for acceleration of the cracking. (authors)

  2. Performance Optimization of Cold Rolled Type 316L Stainless Steel by Sand Blasting and Surface Linishing Treatment

    NASA Astrophysics Data System (ADS)

    Krawczyk, B.; Heine, B.; Engelberg, D. L.

    2016-03-01

    Sand blasting followed by a surface linishing treatment was applied to optimize the near-surface microstructure of cold rolled type 316L stainless steel. The introduction of cold rolling led to the formation of α-martensite. Specimens with large thickness reductions (40, 53%) were more susceptible to localized corrosion. The application of sand blasting produced a near-surface deformation layer containing compressive residual stresses with significantly increased surface roughness, resulting in reduced corrosion resistance. The most resistant microstructure was obtained with the application of a final linishing treatment after sand blasting. This treatment produced microstructures with compressive near-surface residual stresses, reduced surface roughness, and increased resistance to localized corrosion.

  3. CORROSION STUDY FOR THE EFFLUENT TREATMENT FACILITY (ETF) CHROME (VI) REDUCTANT SOLUTION USING 304 & 316L STAINLESS STEEL

    SciTech Connect

    DUNCAN, J.B.

    2007-06-27

    The Effluent Treatment Facility has developed a method to regenerate spent resin from the groundwater pump and treat intercepting chrome(VI) plumes (RPP-RPT-32207, Laboratory Study on Regeneration of Spent DOWEX 21K 16-20 Mesh Ion Exchange Resin). Subsequent laboratory studies have shown that the chrome(VI) may be reduced to chrome(III) by titrating with sodium metabisulfite to an oxidation reduction potential (ORP) of +280 mV at a pH of 2. This test plan describes the use of cyclic potentiodynamic polarization and linear polarization techniques to ascertain the electrochemical corrosion and pitting propensity of the 304 and 316L stainless steel in the acidified reducing the solution that will be contained in either the secondary waste receiver tank or concentrate tank.

  4. Effect of Different Degrees of Sensitization on the EIS Response of 316L and 316 SS in Transpassive Region

    NASA Astrophysics Data System (ADS)

    Morshed Behbahani, K.; Pakshir, M.

    2014-06-01

    Different heat treatments were conducted on 316L and 316 stainless steels, and the sensitized specimens were characterized using anodic polarization and EIS tests in 0.5 M H2SO4 containing 0.01 molar KSCN. The potential ranges related to the transpassive region related to each specimen were determined. The EIS experiments were conducted at different potentials in that region, and the results showed the presence of three different regions, namely the anodic dissolution of the passive layer, dissolution of the grain boundaries, and the occurrence of pitting corrosion owing to the variations in the anodic potential. The higher the applied sensitization temperature, the lower the obtained charge-transfer resistance ( R ct) values, but healing effect was observed at the temperatures above 600 °C for these alloys.

  5. Corrosion resistance of multilayer hybrid sol-gel coatings deposited on the AISI 316L austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Caballero, Y. T.; Rondón, E. A.; Rueda, L.; Hernández Barrios, C. A.; Coy, A.; Viejo, F.

    2016-02-01

    In the present work multilayer hybrid sol-gel coatings were synthesized on the AISI 316L austenitic stainless steel employed in the fabrication of orthopaedic implants. Hybrid sols were obtained from a mixture of inorganic precursor, TEOS, and organic, GPTMS, using ethanol as solvent, and acetic acid as catalyst. The characterization of the sols was performed using pH measurements, rheological tests and infrared spectroscopy (FTIR) for different ageing times. On the other hand, the coatings were characterized by scanning electron microscopy (SEM), while the corrosion resistance was evaluated using anodic potentiodynamic polarization in SBF solution at 37±2°C. The results confirmed that sol-gel synthesis employing TEOS-GPTMS systems produces uniform and homogeneous coatings, which enhanced the corrosion resistance with regard to the parent alloy. Moreover, corrosion performance was retained after applying more than one layer (multilayer coatings).

  6. Effect of Temperature on Galling Behavior of SS 316, 316 L and 416 Under Self-Mated Condition

    NASA Astrophysics Data System (ADS)

    Harsha, A. P.; Limaye, P. K.; Tyagi, Rajnesh; Gupta, Ankit

    2016-10-01

    Galling behavior of three different stainless steels (SS 316, 316 L and 416) was evaluated at room temperature and 300 °C under a self-mated condition. An indigenously fabricated galling tester was used to evaluate the galling performance of mated materials as per ASTM G196-08 standard. The variation in frictional torque was recorded online during the test to assess the onset of galling. The galling50 (G50) stress value was used to compare the galling resistance of a combination of materials, and the results indicate a significant influence of temperature on the galling resistance of the materials tested. This has been attributed to the decrease in hardness and yield strength at elevated temperature which results in softening of the steel and limits its ability to resist severe deformation. Scanning electron micrographs of the galled surface reflected a severe plastic deformation in sliding direction, and a typical adhesive wear mechanism is prevalent during the galling process.

  7. Effect of laser shot peening without coating on the surface properties and corrosion behavior of 316L steel

    NASA Astrophysics Data System (ADS)

    Kalainathan, S.; Sathyajith, S.; Swaroop, S.

    2012-12-01

    This paper discusses the results of laser peening without coating on low carbon austenitic stainless steel 316L. Unlike typical experiments on laser peening without coating (LPwC) performed with frequency doubled (green) laser and underwater irradiation, the present study reports LPwC with infrared radiation using thin layer of water as confinement medium. The dependence of laser pulse density on properties such as surface roughness, surface residual stress, microhardness, and corrosion behavior of LPwC specimen were investigated. The magnitude of surface compressive residual stress on laser peened specimen showed appreciable improvement compared to unpeened base material. Microhardness of the specimen improved by 30-40% after LPwC. However, the potentiodynamic polarization study indicated that though there is an enhancement of corrosion potential (Ecorr), the corrosion current density (Icorr) increased with increase in laser pulse density.

  8. Laser surface alloying of 316L stainless steel coated with a bioactive hydroxyapatite-titanium oxide composite.

    PubMed

    Ghaith, El-Sayed; Hodgson, Simon; Sharp, Martin

    2015-02-01

    Laser surface alloying is a powerful technique for improving the mechanical and chemical properties of engineering components. In this study, laser surface irradiation process employed in the surface modification off 316L stainless steel substrate using hydroxyapatite-titanium oxide to provide a composite ceramic layer for the suitability of applying this technology to improve the biocompatibility of medical alloys and implants. Fusion of the metal surface incorporating hydroxyapatite-titania ceramic particles using a 30 W Nd:YAG laser at different laser powers, 40, 50 and 70% power and a scan speed of 40 mm s(-1) was observed to adopt the optimum condition of ceramic deposition. Coatings were evaluated in terms of microstructure, surface morphology, composition biocompatibility using XRD, ATR-FTIR, SEM and EDS. Evaluation of the in vitro bioactivity by soaking the treated metal in SBF for 10 days showed the deposition of biomimetic apatite.

  9. Effect of bicarbonate ion additives on pitting corrosion of type 316L stainless steel in aqueous 0.5 M sodium chloride solution

    SciTech Connect

    Park, J.J.; Pyun, S.I.; Lee, W.J.; Kim, H.P.

    1999-04-01

    The effect of bicarbonate ions (HCO{sub 3}{sup {minus}}) on pitting corrosion of type 316L stainless steel (SS, UNS S3 1603) was investigated in aqueous 0.5 M sodium chloride (NaCl) solution using potentiodynamic polarization, the abrading electrode technique, alternating current (AC) impedance spectroscopy combined with x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Addition of HCO{sub 3}{sup {minus}} ions to NaCl solutions extended the passive potential region in width and, at the same time, raised the pitting potential in value on the potentiodynamic polarization curve. Potentiostatic current transients obtained from the moment just after interrupting the abrading action showed the repassivation rate of propagating pits increased and that the pit growth rate decreased with increasing HCO{sub 3}{sup {minus}} ion concentration. Over the whole applied potential, the oxide film resistance was higher in the presence of HCO{sub 3}{sup {minus}} ions. The pit number density decreased with increasing HCO{sub 3}{sup {minus}} ion concentration. Moreover, addition of HCO{sub 3}{sup {minus}} ions to NaCl solutions retarded lateral pit growth, while promoting downward pit growth from the surface. The bare surface of the specimen repassivated preferentially along the pit mouth and walls, compared to the pit bottom, as a result of formation of a surface film with a high content of protective mixed ferrous-chromous carbonate ([Fe,Cr]CO{sub 3}) that formed from preferential adsorption of HCO{sub 3}{sup {minus}} ions.

  10. Effects of Thermal Aging on Material Properties, Stress Corrosion Cracking, and Fracture Toughness of AISI 316L Weld Metal

    NASA Astrophysics Data System (ADS)

    Lucas, Timothy; Forsström, Antti; Saukkonen, Tapio; Ballinger, Ronald; Hänninen, Hannu

    2016-08-01

    Thermal aging and consequent embrittlement of materials are ongoing issues in cast stainless steels, as well as duplex, and high-Cr ferritic stainless steels. Spinodal decomposition is largely responsible for the well-known "748 K (475 °C) embrittlement" that results in drastic reductions in ductility and toughness in these materials. This process is also operative in welds of either cast or wrought stainless steels where δ-ferrite is present. While the embrittlement can occur after several hundred hours of aging at 748 K (475 °C), the process is also operative at lower temperatures, at the 561 K (288 °C) operating temperature of a boiling water reactor (BWR), for example, where ductility reductions have been observed after several tens of thousands of hours of exposure. An experimental program was carried out in order to understand how spinodal decomposition may affect changes in material properties in Type 316L BWR piping weld metals. The study included material characterization, nanoindentation hardness, double-loop electrochemical potentiokinetic reactivation (DL-EPR), Charpy-V, tensile, SCC crack growth, and in situ fracture toughness testing as a function of δ-ferrite content, aging time, and temperature. SCC crack growth rates of Type 316L stainless steel weld metal under simulated BWR conditions showed an approximate 2 times increase in crack growth rate over that of the unaged as-welded material. In situ fracture toughness measurements indicate that environmental exposure can result in a reduction of toughness by up to 40 pct over the corresponding at-temperature air-tested values. Material characterization results suggest that spinodal decomposition is responsible for the degradation of material properties measured in air, and that degradation of the in situ properties may be a result of hydrogen absorbed during exposure to the high-temperature water environment.

  11. The influence of nanostructured features on bacterial adhesion and bone cell functions on severely shot peened 316L stainless steel.

    PubMed

    Bagherifard, Sara; Hickey, Daniel J; de Luca, Alba C; Malheiro, Vera N; Markaki, Athina E; Guagliano, Mario; Webster, Thomas J

    2015-12-01

    Substrate grain structure and topography play major roles in mediating cell and bacteria activities. Severe plastic deformation techniques, known as efficient metal-forming and grain refining processes, provide the treated material with novel mechanical properties and can be adopted to modify nanoscale surface characteristics, possibly affecting interactions with the biological environment. This in vitro study evaluates the capability of severe shot peening, based on severe plastic deformation, to modulate the interactions of nanocrystallized metallic biomaterials with cells and bacteria. The treated 316L stainless steel surfaces were first investigated in terms of surface topography, grain size, hardness, wettability and residual stresses. The effects of the induced surface modifications were then separately studied in terms of cell morphology, adhesion and proliferation of primary human osteoblasts (bone forming cells) as well as the adhesion of multiple bacteria strains, specifically Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and ampicillin-resistant Escherichia coli. The results indicated a significant enhancement in surface work hardening and compressive residual stresses, maintenance of osteoblast adhesion and proliferation as well as a remarkable decrease in the adhesion and growth of gram-positive bacteria (S. aureus and S. epidermidis) compared to non-treated and conventionally shot peened samples. Impressively, the decrease in bacteria adhesion and growth was achieved without the use of antibiotics, for which bacteria can develop a resistance towards anyway. By slightly grinding the surface of severe shot peened samples to remove differences in nanoscale surface roughness, the effects of varying substrate grain size were separated from those of varying surface roughness. The expression of vinculin focal adhesions from osteoblasts was found to be singularly and inversely related to grain size, whereas the attachment of gram

  12. The influence of nanostructured features on bacterial adhesion and bone cell functions on severely shot peened 316L stainless steel.

    PubMed

    Bagherifard, Sara; Hickey, Daniel J; de Luca, Alba C; Malheiro, Vera N; Markaki, Athina E; Guagliano, Mario; Webster, Thomas J

    2015-12-01

    Substrate grain structure and topography play major roles in mediating cell and bacteria activities. Severe plastic deformation techniques, known as efficient metal-forming and grain refining processes, provide the treated material with novel mechanical properties and can be adopted to modify nanoscale surface characteristics, possibly affecting interactions with the biological environment. This in vitro study evaluates the capability of severe shot peening, based on severe plastic deformation, to modulate the interactions of nanocrystallized metallic biomaterials with cells and bacteria. The treated 316L stainless steel surfaces were first investigated in terms of surface topography, grain size, hardness, wettability and residual stresses. The effects of the induced surface modifications were then separately studied in terms of cell morphology, adhesion and proliferation of primary human osteoblasts (bone forming cells) as well as the adhesion of multiple bacteria strains, specifically Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and ampicillin-resistant Escherichia coli. The results indicated a significant enhancement in surface work hardening and compressive residual stresses, maintenance of osteoblast adhesion and proliferation as well as a remarkable decrease in the adhesion and growth of gram-positive bacteria (S. aureus and S. epidermidis) compared to non-treated and conventionally shot peened samples. Impressively, the decrease in bacteria adhesion and growth was achieved without the use of antibiotics, for which bacteria can develop a resistance towards anyway. By slightly grinding the surface of severe shot peened samples to remove differences in nanoscale surface roughness, the effects of varying substrate grain size were separated from those of varying surface roughness. The expression of vinculin focal adhesions from osteoblasts was found to be singularly and inversely related to grain size, whereas the attachment of gram

  13. Microstructural characterization of an SA508–309L/308L–316L domestic dissimilar metal welded safe-end joint

    SciTech Connect

    Ming, Hongliang; Zhang, Zhiming; Wang, Jianqiu Han, En-Hou; Ke, Wei

    2014-11-15

    The microstructure of an SA508–309L/308L–316L domestic dissimilar metal welded safe-end joint was characterized in this work by optical microscopy, scanning electron microscopy (with electron back scattering diffraction) and micro-hardness testing. Epitaxial growth and competitive growth are evident in the 308L–316L fusion boundary regions. A martensite layer, carbon-depleted zones, and type-II and type-I boundaries are found in the SA508–309L fusion boundary regions, while only martensite and austenite mixed zones are observed in the SA508–308L fusion boundary regions. The microstructure near the fusion boundary and the microstructure transition in the SA508 heat affected zone are quite complex. Both for SA508–309L/308L and 308L–316L, the highest residual strain is located on the outside of the weldment. The residual strain and the grain boundary character distribution change with increasing distance from the fusion boundary in the heat affected zone of 316L. Micro-hardness measurements also reveal non-uniform mechanical properties across the weldment. - Highlights: • The microstructure of SA508 HAZ, especially near the FB, is very complex. • The outside of the dissimilar metal welded joint has the highest residual. • The micro-hardness distributions along the DMWJ are non-uniform.

  14. The covalent immobilization of heparin to pulsed-plasma polymeric allylamine films on 316L stainless steel and the resulting effects on hemocompatibility.

    PubMed

    Yang, Zhilu; Wang, Jin; Luo, Rifang; Maitz, Manfred F; Jing, Fengjuan; Sun, Hong; Huang, Nan

    2010-03-01

    For an improved hemocompatibility of 316L stainless steel (SS), we develop a facile and effective approach to fabricating a pulsed-plasma polymeric allylamine (P-PPAm) film that possesses a high cross-linking degree and a high density of amine groups, which is used for subsequent bonding of heparin. The P-PPAm film as a stent coating shows good resistance to the deformation behavior of compression and expansion of a stent. Using deionized water as an aging medium, it is demonstrated that the heparin-immobilized P-PPAm (Hep-P-PPAm) surface has a good retention of heparin. The systematic in vitro hemocompatibility evaluation reveals lower platelet adhesion, platelet activation and fibrinogen activation on the Hep-P-PPAm surface, and the activated partial thromboplastin time prolongs for about 15 s compared with 316L SS. The P-PPAm surface significantly promotes adhesion and proliferation of endothelial cells (ECs). For the Hep-P-PPAm, although EC adhesion and proliferation is slightly suppressed initially, after cultivation for 3 days, the growth behavior of ECs is remarkably improved over 316L SS. In vivo results indicate that the Hep-P-PPAm surface successfully restrain thrombus formation by growing a homogeneous and intact shuttle-like endothelium on its surface. The Hep-P-PPAm modified 316L SS shows a promising application for vascular devices.

  15. Effect of dissolved oxygen content on stress corrosion cracking of a cold worked 316L stainless steel in simulated pressurized water reactor primary water environment

    NASA Astrophysics Data System (ADS)

    Zhang, Litao; Wang, Jianqiu

    2014-03-01

    Stress corrosion crack growth tests of a cold worked nuclear grade 316L stainless steel were conducted in simulated pressurized water reactor (PWR) primary water environment containing various dissolved oxygen (DO) contents but no dissolved hydrogen. The crack growth rate (CGR) increased with increasing DO content in the simulated PWR primary water. The fracture surface exhibited typical intergranular stress corrosion cracking (IGSCC) characteristics.

  16. Biofilm initiation and growth of Pseudomonas aeruginosa on 316L stainless steel in low gravity in orbital space flight

    NASA Astrophysics Data System (ADS)

    Todd, Paul; Pierson, Duane L.; Allen, Britt; Silverstein, JoAnn

    The formation of biofilms by water microorganisms such as Pseudomonas aeruginosa in spacecraft water systems has been a matter of concern for long-duration space flight. Crewed spacecraft plumbing includes internal surfaces made of 316L stainless steel. Experiments were therefore undertaken to compare the ability of P. aeruginosa to grow in suspension, attach to stainless steel and to grow on stainless steel in low gravity on the space shuttle. Four categories of cultures were studied during two space shuttle flights (STS-69 and STS-77). Cultures on the ground were held in static horizontal or vertical cylindrical containers or were tumbled on a clinostat and activated under conditions identical to those for the flown cultures. The containers used on the ground and in flight were BioServe Space Technologies’ Fluid Processing Apparatus (FPA), an open-ended test tube with rubber septa that allows robotic addition of bacteria to culture media to initiate experiments and the addition of fixative to conclude experiments. Planktonic growth was monitored by spectrophotometry, and biofilms were characterized quantitatively by epifluorescence and scanning electron microscopy. In these experiments it was found that: (1) Planktonic growth in flown cultures was more extensive than in static cultures, as seen repeatedly in the history of space microbiology, and closely resembled the growth of tumbled cultures. (2) Conversely, the attachment of cells in flown cultures was as much as 8 times that in tumbled cultures but not significantly different from that in static horizontal and vertical cultures, consistent with the notion that flowing fluid reduces microbial attachment. (3) The final surface coverage in 8 days was the same for flown and static cultures but less by a factor of 15 in tumbled cultures, where coverage declined during the preceding 4 days. It is concluded that cell attachment to 316L stainless steel in the low gravity of orbital space flight is similar to that

  17. Effect of thermal treatment on the corrosion resistance of Type 316L stainless steel exposed in supercritical water

    NASA Astrophysics Data System (ADS)

    Jiao, Y.; Zheng, W.; Guzonas, D. A.; Cook, W. G.; Kish, J. R.

    2015-09-01

    There are still unknown aspects about the growth mechanism of oxide scales formed on candidate stainless steel fuel cladding materials during exposure in supercritical water (SCW) under the conditions relevant to the Canadian supercritical water-cooled reactor (SCWR). The tendency for intermetallic precipitates to form within the grains and on grain boundaries during prolonged exposure at high temperatures represents an unknown factor to corrosion resistance, since they tend to bind alloyed Cr. The objective of this study was to better understand the extent to which intermetallic precipitates affects the mode and extent of corrosion in SCW. Type 316L stainless steel, used as a model Fe-Cr-Ni-Mo alloy, was exposed to 25 MPa SCW at 550 °C for 500 h in a static autoclave for this purpose. Mechanically-abraded samples were tested in the mill-annealed (MA) and a thermally-treated (TT) condition. The thermal treatment was conducted at 815 °C for 1000 h to precipitate the carbide (M23C6), chi (χ), laves (η) and sigma (σ) phases. It was found that although relatively large intermetallic precipitates formed at the scale/alloy interface locally affected the oxide scale formation, their discontinuous formation did not affect the short-term overall apparent corrosion resistance.

  18. The Effect of Post-Heat Treatment on Microstructure of 316L Cold-Sprayed Coatings and Their Corrosion Performance

    NASA Astrophysics Data System (ADS)

    Dikici, B.; Yilmazer, H.; Ozdemir, I.; Isik, M.

    2016-04-01

    The combined effects of process gases and post-heat treatment temperature on the microstructure of 316L cold-sprayed coatings on Al5052 substrates have been investigated in this study. The stainless steel coatings were subjected to heat treatment at four different temperatures (250, 500, 750, and 1000 °C) to study the effect of heat treatment. In addition, the corrosion performances of the coatings at different process temperatures have been compared using the potentiodynamic scanning technique. Microstructural characterization of the coatings was carried out using scanning and transmission electron microscopy and x-ray diffraction. The results of present study showed that cold-sprayed stainless steel coatings processed with helium exhibited higher corrosion resistance than those of coatings sprayed with nitrogen process gas. This could partially be attributed to the reduction in porosity level (4.9%) and improvement of particle-particle bonding. In addition, evaluation of the mechanical and microstructural properties of the coatings demonstrated that subsequent heat treatment has major influence on the deposited layers sprayed with He process gas.

  19. An EBSD investigation on flow localization and microstructure evolution of 316L stainless steel for Gen IV reactor applications

    NASA Astrophysics Data System (ADS)

    Wu, Xianglin; Pan, Xiao; Mabon, James C.; Li, Meimei; Stubbins, James F.

    2007-09-01

    Type 316L stainless steel has been selected as a candidate structural material in a series of current accelerator driven systems and Generation IV reactor conceptual designs. The material is sensitive to irradiation damage in the temperature range of 150-400 °C: even low levels of irradiation exposure, as small as 0.1 dpa, can cause severe loss of ductility during tensile loading. This process, where the plastic flow becomes highly localized resulting in extremely low overall ductility, is referred as flow localization. The process controlling this confined flow is related to the difference between the yield and ultimate tensile strengths such that large irradiation-induced increases in the yield strength result in very limited plastic flow leading to necking after very small levels of uniform elongation. In this study, the microstructural evolution controlling flow localization is examined. It is found that twinning is an important deformation mechanism at lower temperatures since it promotes the strain hardening process. At higher temperatures, twinning becomes energetically impossible since the activation of twinning is determined by the critical twinning stress, which increases rapidly with temperature. Mechanical twinning and dislocation-based planar slip are competing mechanisms for plastic deformation.

  20. Radiation-induced stress relaxation in high temperature water of type 316L stainless steel evaluated by neutron diffraction

    NASA Astrophysics Data System (ADS)

    Ishiyama, Y.; Rogge, R. B.; Obata, M.

    2011-01-01

    Weld beads on plate specimens made of type 316L stainless steel were neutron-irradiated up to about 2.5 × 10 25 n/m 2 ( E > 1 MeV) at 561 K in the Japan Material Testing Reactor (JMTR). Residual stresses of the specimens were measured by the neutron diffraction method, and the radiation-induced stress relaxation was evaluated. The values of σ x residual stress (transverse to the weld bead) and σ y residual stress (longitudinal to the weld bead) decreased with increasing neutron dose. The tendency of the stress relaxation was almost the same as previously published data, which were obtained for type 304 stainless steel. From this result, it was considered that there was no steel type dependence on radiation-induced stress relaxation. The neutron irradiation dose dependence of the stress relaxation was examined using an equation derived from the irradiation creep equation. The coefficient of the stress relaxation equation was obtained, and the value was 1.4 (×10 -6/MPa/dpa). This value was smaller than that of nickel alloy.

  1. Influence of flowing sodium on creep deformation and rupture behaviour of 316L(N) austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Ravi, S.; Laha, K.; Mathew, M. D.; Vijayaraghavan, S.; Shanmugavel, M.; Rajan, K. K.; Jayakumar, T.

    2012-08-01

    The influence of flowing sodium on creep deformation and rupture behaviour of AISI 316L(N) austenitic stainless steel has been investigated at 873 K over a stress range of 235-305 MPa. The results were compared with those obtained from testing in air environment. The steady state creep rates of the material were not influenced appreciably by the testing environments. The time to onset of tertiary stage of creep deformation was delayed in sodium environment. The creep-rupture lives of the material increased in sodium environment, which became more pronounced at lower applied stresses. The increase in rupture life of the material in flowing sodium was accompanied by an increase in rupture ductility. The creep damage on specimen surface as well as inside the specimen was less in specimen tested in sodium. SEM fractographic investigation revealed predominantly transgranular dimple failure for the specimen tested in sodium, whereas predominantly intergranular creep failure was observed in the air tested specimens. Almost no oxidation was observed in the specimens creep tested in the sodium environment. Absence of oxidation and less creep damage cavitation extended the secondary state in liquid sodium tests and lead to increase in creep rupture life and ductility of the material as compared to in air.

  2. Electrochemical and In Vitro Behavior of Nanostructure Sol-Gel Coated 316L Stainless Steel Incorporated with Rosemary Extract

    NASA Astrophysics Data System (ADS)

    Motalebi, Abolfazl; Nasr-Esfahani, Mojtaba

    2013-06-01

    The corrosion resistance of AISI 316L stainless steel for biomedical applications, was significantly enhanced by means of hybrid organic-inorganic sol-gel thin films deposited by spin-coating. Thin films of less than 100 nm with different hybrid characters were obtained by incorporating rosemary extract as green corrosion inhibitor. The morphology, composition, and adhesion of hybrid sol-gel coatings have been examined by SEM, EDX, and pull-off test, respectively. Addition of high additive concentrations (0.1%) did not disorganize the sol-gel network. Direct pull-off test recorded a mean coating-substrate bonding strength larger than 21.2 MPa for the hybrid sol-gel coating. The effect of rosemary extract, with various added concentrations from 0.012 to 0.1%, on the anticorrosion properties of sol-gel films have been characterized by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in simulated body fluid (SBF) solution and has been compared to the bare metal. Rosemary extract additions (0.05%) have significantly increased the corrosion protection of the sol-gel thin film to higher than 90%. The in vitro bioactivity of prepared films indicates that hydroxyapatite nuclei can form and grow on the surface of the doped sol-gel thin films. The present study shows that due to their excellent anticorrosion properties, bioactivity and bonding strength to substrate, doped sol-gel thin films are practical hybrid films in biomedical applications.

  3. Influence of the 316 L stainless steel interface on the stability and barrier properties of plasma fluorocarbon films.

    PubMed

    Lewis, François; Cloutier, Maxime; Chevallier, Pascale; Turgeon, Stéphane; Pireaux, Jean-Jacques; Tatoulian, Michael; Mantovani, Diego

    2011-07-01

    Coatings are known to be one of the more suited strategies to tailor the interface between medical devices and the surrounding cells and tissues once implanted. The development of coatings and the optimization of their adhesion and stability are of major importance. In this work, the influence of plasma etching of the substrate on a plasma fluorocarbon ultrathin coating has been investigated with the aim of improving the stability and the corrosion properties of coated medical devices. The 316 L stainless steel interface was subjected to two different etching sequences prior to the plasma deposition. These plasma etchings, with H(2) and C(2)F(6) as gas precursors, modified the chemical composition and the thickness of the oxide layer and influenced the subsequent polymerization. The coating properties were evaluated using flat substrates submitted to deformation, aging into aqueous medium and corrosion tests. X-ray photoelectron spectroscopy (XPS), time of flight-secondary ion mass spectrometry (ToF-SIMS), ellipsometry, and atomic force microscopy (AFM) were performed to determine the effects of the deformation and the aging on the chemistry and morphology of the coated samples. Analyses showed that plasma etchings were essential to promote reproducible polymerization and film growth. However, the oxide layer thinning due to the etching lowered the corrosion resistance of the substrate and affected the stability of the interface. Still, the deformed samples did not exhibited adhesion and cohesion failure before and after the aging.

  4. Microstructural Variations Across a Dissimilar 316L Austenitic: 9Cr Reduced Activation Ferritic Martensitic Steel Weld Joint

    NASA Astrophysics Data System (ADS)

    Thomas Paul, V.; Karthikeyan, T.; Dasgupta, Arup; Sudha, C.; Hajra, R. N.; Albert, S. K.; Saroja, S.; Jayakumar, T.

    2016-03-01

    This paper discuss the microstructural variations across a dissimilar weld joint between SS316 and 9Cr-RAFM steel and its modifications on post weld heat treatments (PWHT). Detailed characterization showed a mixed microstructure of austenite and martensite in the weld which is in agreement with the phases predicted using Schaeffler diagram based on composition measurements. The presence of very low volume fraction of δ-ferrite in SS316L has been identified employing state of the art electron back-scattered diffraction technique. PWHT of the ferritic steel did not reduce the hardness in the weld metal. Thermal exposure at 973 K (700 °C) showed a progressive reduction in hardness of weld joint with duration of treatment except in austenitic base metal. However, diffusion annealing at 1073 K (800 °C) for 100 hours resulted in an unexpected increase in hardness of weld metal, which is a manifestation of the dilution effects and enrichment of Ni on the transformation characteristics of the weld zone. Migration of carbon from ferritic steel aided the precipitation of fine carbides in the austenitic base metal on annealing at 973 K (700 °C); but enhanced diffusion at 1073 K (880 °C) resulted in coarsening of carbides and thereby reduction of hardness.

  5. Summary of recommended correlations for ITER-grade type 316L(N) for the ITER materials properties handbook

    SciTech Connect

    Billone, M.C.; Pawel, J.E.

    1996-04-01

    The focus of this effort is the effects of irradiation on the ultimate tensile strengths (UTS), the yield strength (YS), the uniform elongation (UE), the total elongation (TE) and the reduction in area (RA) in the ITER-relevant temperature range of 100-400{degrees}C. For the purpose of this summary, data for European heats of 316 with 0.020.08 wt.% are referred to as E316L(N) data and grouped together. Other heats of 316 and Ti-modified 316 are also included in the data base. For irradiation and postirradiation-test temperatures in the range of 200-400{degrees}C, the common behavior of these heats of stainless steel is a yield strength approaching the ultimate tensile strength approaching 800 MPa, a uniform elongation approaching 0.3%, a total elongation approaching 3-9%, and a high (about 60%) reduction in area as the neutron damage approaches 10 dpa.

  6. Reduced platelet adhesion and improved corrosion resistance of superhydrophobic TiO₂-nanotube-coated 316L stainless steel.

    PubMed

    Huang, Qiaoling; Yang, Yun; Hu, Ronggang; Lin, Changjian; Sun, Lan; Vogler, Erwin A

    2015-01-01

    Superhydrophilic and superhydrophobic TiO2 nanotube (TNT) arrays were fabricated on 316L stainless steel (SS) to improve corrosion resistance and hemocompatibility of SS. Vertically-aligned superhydrophilic amorphous TNTs were fabricated on SS by electrochemical anodization of Ti films deposited on SS. Calcination was carried out to induce anatase phase (superhydrophilic), and fluorosilanization was used to convert superhydrophilicity to superhydrophobicity. The morphology, structure and surface wettability of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and contact angle goniometry. The effects of surface wettability on corrosion resistance and platelet adhesion were investigated. The results showed that crystalline phase (anatase vs. amorphous) and wettability strongly affected corrosion resistance and platelet adhesion. The superhydrophilic amorphous TNTs failed to protect SS from corrosion whereas superhydrophobic amorphous TNTs slightly improved corrosion resistance of SS. Both superhydrophilic and superhydrophobic anatase TNTs significantly improved corrosion resistance of SS. The superhydrophilic amorphous TNTs minimized platelet adhesion and activation whereas superhydrophilic anatase TNTs activated the formation of fibrin network. On the contrary, both superhydrophobic TNTs (superhydrophobic amorphous TNTs and superhydrophobic anatase TNTs) reduced platelet adhesion significantly and improved corrosion resistance regardless of crystalline phase. Superhydrophobic anatase TNTs coating on SS surface offers the opportunity for the application of SS as a promising permanent biomaterial in blood contacting biomedical devices, where both reducing platelets adhesion/activation and improving corrosion resistance can be effectively combined. PMID:25481855

  7. TEM study of the nucleation of bubbles induced by He implantation in 316L industrial austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Jublot-Leclerc, S.; Lescoat, M.-L.; Fortuna, F.; Legras, L.; Li, X.; Gentils, A.

    2015-11-01

    10 keV He ions were implanted in-situ in a TEM into thin foils of 316L industrial austenitic stainless steel at temperatures ranging from 200 to 550 °C. As a result, overpressurized nanometric bubbles are created with density and size depending strongly on both the temperature and fluence of implantation. An investigation on their nucleation and growth is reported through a rigorous statistical analysis whose procedure, including the consideration of free surface effects, is detailed. In the parameter range considered, the results show that an increase of fluence promotes both the nucleation and growth of the bubbles whilst an increase of temperature enhances the growth of the bubbles at the expense of their nucleation. The confrontation of resulting activation energies with existing models for bubble nucleation enables the identification of the underlying mechanisms. In spite of slight differences resulting from different conditions of implantation among which the He concentration, He production rate and He/dpa ratio, it appears that the dominating mechanisms are the same as those obtained in metals in previous studies, which, in addition to corroborating literature results, shows the suitability of in-situ TEM experiments to simulate the production of helium in nuclear materials.

  8. Stress corrosion cracking and corrosion fatigue on 316L stainless steel in boric acid concentrated media at 320 C

    SciTech Connect

    Herms, E.; Olive, J.M.; Puiggali, M.; Boursier, J.M.

    1999-07-01

    Stress Corrosion Cracking (SCC) and Corrosion-Fatigue (CF) tests were performed in autoclave at 320 C in concentrated boric acid chlorinated media in presence of oxygen or hydrogen on type 316L austenitic stainless steel. Crack Growth Rates (CGR) are higher in non deaerated solutions for both SCC and CF than in hydrogenated solutions. CGR are relatively similar in CF and in SCC, excepted for high load ratio in CF where CGR are higher than in SCC. Detailed analysis of the fracture surface shows some distinct features between SCC and CF. Intergranular and transgranular mode of fracture are observed on SCC and CF. Fracture modes depend on the chemistry of solution in SCC and on frequency in CF. Traces of slip bands and crack front marking associated with oxide scale present on fracture surfaces exist in SCC and CF. Fatigue striations appear for low load ratio and high frequency. Secondary intergranular and transgranular cracking is observed only on SCC fracture surfaces and ligament morphology can be different in SCC relative to FC.

  9. MC3T3-E1 cell response to stainless steel 316L with different surface treatments.

    PubMed

    Zhang, Hongyu; Han, Jianmin; Sun, Yulong; Huang, Yongling; Zhou, Ming

    2015-11-01

    In the present study, stainless steel 316L samples with polishing, aluminum oxide blasting, and hydroxyapatite (HA) coating were prepared and characterized through a scanning electron microscope (SEM), optical interferometer (surface roughness, Sq), contact angle, surface composition and phase composition analyses. Osteoblast-like MC3T3-E1 cell adhesion on the samples was investigated by cell morphology using a SEM (4h, 1d, 3d, 7d), and cell proliferation was assessed by MTT method at 1d, 3d, and 7d. In addition, adsorption of bovine serum albumin on the samples was evaluated at 1h. The polished sample was smooth (Sq: 1.8nm), and the blasted and HA coated samples were much rougher (Sq: 3.2μm and 7.8μm). Within 1d of incubation, the HA coated samples showed the best cell morphology (e.g., flattened shape and complete spread), but there was no significant difference after 3d and 7d of incubation for all the samples. The absorbance value for the HA coated samples was the highest after 1d and 3d of incubation, indicating better cell viability. However, it reduced to the lowest value at 7d. Protein adsorption on the HA coated samples was the highest at 1h. The results indicate that rough stainless steel surface improves cell adhesion and morphology, and HA coating contributes to superior cell adhesion, but inhibits cell proliferation.

  10. Reduced platelet adhesion and improved corrosion resistance of superhydrophobic TiO₂-nanotube-coated 316L stainless steel.

    PubMed

    Huang, Qiaoling; Yang, Yun; Hu, Ronggang; Lin, Changjian; Sun, Lan; Vogler, Erwin A

    2015-01-01

    Superhydrophilic and superhydrophobic TiO2 nanotube (TNT) arrays were fabricated on 316L stainless steel (SS) to improve corrosion resistance and hemocompatibility of SS. Vertically-aligned superhydrophilic amorphous TNTs were fabricated on SS by electrochemical anodization of Ti films deposited on SS. Calcination was carried out to induce anatase phase (superhydrophilic), and fluorosilanization was used to convert superhydrophilicity to superhydrophobicity. The morphology, structure and surface wettability of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and contact angle goniometry. The effects of surface wettability on corrosion resistance and platelet adhesion were investigated. The results showed that crystalline phase (anatase vs. amorphous) and wettability strongly affected corrosion resistance and platelet adhesion. The superhydrophilic amorphous TNTs failed to protect SS from corrosion whereas superhydrophobic amorphous TNTs slightly improved corrosion resistance of SS. Both superhydrophilic and superhydrophobic anatase TNTs significantly improved corrosion resistance of SS. The superhydrophilic amorphous TNTs minimized platelet adhesion and activation whereas superhydrophilic anatase TNTs activated the formation of fibrin network. On the contrary, both superhydrophobic TNTs (superhydrophobic amorphous TNTs and superhydrophobic anatase TNTs) reduced platelet adhesion significantly and improved corrosion resistance regardless of crystalline phase. Superhydrophobic anatase TNTs coating on SS surface offers the opportunity for the application of SS as a promising permanent biomaterial in blood contacting biomedical devices, where both reducing platelets adhesion/activation and improving corrosion resistance can be effectively combined.

  11. Residual stress in nano-structured stainless steel (AISI 316L) prompted by Xe+ ion bombardment at different impinging angles

    NASA Astrophysics Data System (ADS)

    Cucatti, S.; Droppa, R.; Figueroa, C. A.; Klaus, M.; Genzel, Ch.; Alvarez, F.

    2016-10-01

    The effect of low energy (<1 keV) xenon (Xe+) ion bombardment on the residual stress of polycrystalline iron alloy (AISI 316L steel) is reported. The results take into account the influence of the ion incident angle maintaining constant all other bombarding parameters (i.e., ion energy and current density, temperature, and doses). The bombarded surface topography shows that ions prompt the formation of nanometric regular patterns on the surface crystalline grains and stressing the structure. The paper focalizes on the study of the surface residual stress state stemming from the ion bombardment studied by means of the "sin2 ψ" and "Universal Plot" methods. The analysis shows the absence of shear stress in the affected material region and the presence of compressive in-plane residual biaxial stress (˜200 MPa) expanding up to ˜1 μm depth for all the studied samples. Samples under oblique bombardment present higher compressive stress values in the direction of the projected ion beam on the bombarded surface. The absolute value of the biaxial surface stress difference (σ11-σ22) increases on ion impinging angles, a phenomenon associated with the momentum transfer by the ions. The highest stress level was measured for ion impinging angles of 45° ( σ 11 = -380 ± 10 MPa and σ 22 = -320 ± 10 MPa). The different stresses obtained in the studied samples do not affect significantly the formation of characteristic surface patterns.

  12. Effect of Austenitic and Austeno-Ferritic Electrodes on 2205 Duplex and 316L Austenitic Stainless Steel Dissimilar Welds

    NASA Astrophysics Data System (ADS)

    Verma, Jagesvar; Taiwade, Ravindra V.

    2016-09-01

    This study addresses the effect of different types of austenitic and austeno-ferritic electrodes (E309L, E309LMo and E2209) on the relationship between weldability, microstructure, mechanical properties and corrosion resistance of shielded metal arc welded duplex/austenitic (2205/316L) stainless steel dissimilar joints using the combined techniques of optical, scanning electron microscope, energy-dispersive spectrometer and electrochemical. The results indicated that the change in electrode composition led to microstructural variations in the welds with the development of different complex phases such as vermicular ferrite, lathy ferrite, widmanstatten and intragranular austenite. Mechanical properties of welded joints were diverged based on compositions and solidification modes; it was observed that ferritic mode solidified weld dominated property wise. However, the pitting corrosion resistance of all welds showed different behavior in chloride solution; moreover, weld with E2209 was superior, whereas E309L exhibited lower resistance. Higher degree of sensitization was observed in E2209 weld, while lesser in E309L weld. Optimum ferrite content was achieved in all welds.

  13. Study on cerium-doped nano-TiO2 coatings for corrosion protection of 316 L stainless steel

    NASA Astrophysics Data System (ADS)

    Li, Suning; Wang, Qian; Chen, Tao; Zhou, Zhihua; Wang, Ying; Fu, Jiajun

    2012-04-01

    Many methods have been reported on improving the photogenerated cathodic protection of nano-TiO2 coatings for metals. In this work, nano-TiO2 coatings doped with cerium nitrate have been developed by sol-gel method for corrosion protection of 316 L stainless steel. Surface morphology, structure, and properties of the prepared coatings were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The corrosion protection performance of the prepared coatings was evaluated in 3 wt% NaCl solution by using electrochemical techniques in the presence and absence of simulated sunlight illumination. The results indicated that the 1.2% Ce-TiO2 coating with three layers exhibited an excellent photogenerated cathodic protection under illumination attributed to the higher separation efficiency of electron-hole pairs and higher photoelectric conversion efficiency. The results also showed that after doping with an appropriate concentration of cerium nitrate, the anti-corrosion performance of the TiO2 coating was improved even without irradiation due to the self-healing property of cerium ions.

  14. Microstructural Development and Technical Challenges in Laser Additive Manufacturing: Case Study with a 316L Industrial Part

    NASA Astrophysics Data System (ADS)

    Marya, Manuel; Singh, Virendra; Marya, Surendar; Hascoet, Jean Yves

    2015-08-01

    Additive manufacturing (AM) brings disruptive changes to the ways parts, and products are designed, fabricated, tested, qualified, inspected, marketed, and sold. These changes introduce novel technical challenges and concerns arising from the maturity and diversity of today's AM processes, feedstock materials, and process parameter interactions. AM bears a resemblance with laser and electron beam welding in the so-called conduction mode, which involves a multitude of dynamic physical events between the projected feedstock and a moving heat source that eventually influence AM part properties. For this paper, an air vent was selected for its thin-walled, hollow, and variable cross section, and limited size. The studied air vents, randomly selected from a qualification batch, were fabricated out of 316L stainless steel using a 4 kW fiber laser powder-fed AM system, referred to as construction laser additive direct (CLAD). These were systematically characterized by microhardness indentation, visual examination, optical and scanning electron microscopy, and electron-back-scattering diffraction in order to determine AM part suitability for service and also broadly discuss metallurgical phenomena. The paper then briefly expands the discussion to include additional engineering alloys and further analyze relationships between AM process parameters and AM part properties, consistently utilizing past experience with the same powder-fed CLAD 3D printer, the well-established science and technology of welding and joining, and recent publications on additive manufacturing.

  15. Plasma surface oxidation of 316L stainless steel for improving adhesion strength of silicone rubber coating to metal substrate

    NASA Astrophysics Data System (ADS)

    Latifi, Afrooz; Imani, Mohammad; Khorasani, Mohammad Taghi; Daliri Joupari, Morteza

    2014-11-01

    Stainless steel 316L is one of the most widely used materials for fabricating of biomedical devices hence, improving its surface properties is still of great interest and challenging in biomaterial sciences. Plasma oxidation, in comparison to the conventional chemical or mechanical methods, is one of the most efficient methods recently used for surface treatment of biomaterials. Here, stainless steel specimens were surface oxidized by radio-frequency plasma irradiation operating at 34 MHz under pure oxygen atmosphere. Surface chemical composition of the samples was significantly changed after plasma oxidation by appearance of the chromium and iron oxides on the plasma-oxidized surface. A wettable surface, possessing high surface energy (83.19 mN m-1), was observed after plasma oxidation. Upon completion of the surface modification process, silicone rubber was spray coated on the plasma-treated stainless steel surface. Morphology of the silicone rubber coating was investigated by scanning electron microscopy (SEM). A uniform coating was formed on the oxidized surface with no delamination at polymer-metal interface. Pull-off tests showed the lowest adhesion strength of coating to substrate (0.12 MPa) for untreated specimens and the highest (0.89 MPa) for plasma-oxidized ones.

  16. A Study on the Effects of the Use of Gas or Water Atomized AISI 316L Steel Powder on the Corrosion Resistance of Laser Deposited Material

    NASA Astrophysics Data System (ADS)

    Tobar, M. J.; Amado, J. M.; Montero, J.; Yáñez, A.

    Water atomized and gas atomized powders are commonly used in 3D laser manufacturing. Both types of AISI 316L stainless steel powders are available which differ in their manganese content. This is due to specific procedures related to the two different atomization process. The amount of manganese in the laser processed part might have important implications in its corrosion resistance. It could lead to the formation of manganese sulfides (MnS) which are known to be initiation sites for pitting corrosion. In this work, corrosion performance of laser deposited 316L steel using gas and atomized powders is compared by means of potentiodynamic polarization tests in 0.35%wt. NaCL solution. Worse performance of the gas atomized samples is observed as with respect to the water atomized ones in terms of polarization resistance, corrosion rate and pitting susceptibility.

  17. The structural and bio-corrosion barrier performance of Mg-substituted fluorapatite coating on 316L stainless steel human body implant

    NASA Astrophysics Data System (ADS)

    Sharifnabi, A.; Fathi, M. H.; Eftekhari Yekta, B.; Hossainalipour, M.

    2014-01-01

    In this study, Mg-substituted fluorapatite coatings were deposited on medical grade AISI 316L stainless steel via sol-gel dip coating method. Phase composition, crystallite size and degree of crystallinity of the obtained coatings were evaluated by X-ray diffraction (XRD) analysis. Fourier transform infrared (FTIR) spectroscopy was also used to evaluate functional groups of the obtained coatings. The surface morphology and cross-section of the final coatings were studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy was used to determine elemental chemical composition of the obtained coatings. In order to determine and compare the corrosion behavior of uncoated and Mg-substituted fluorapatite coated 316L stainless steel, electrochemical potentiodynamic polarization tests were performed in physiological solutions at 37 ± 1 °C. Moreover, the released metallic ions from uncoated and coated substrates were measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) within 2 months of immersing in Ringer's solution at 36.5 ± 1 °C as an indication of biocompatibility. The results showed that fluoride and magnesium were successfully incorporated into apatite lattice structure and the prepared coatings were nanostructured with crystallinity of about 70%. Obtained coatings were totally crack-free and uniform and led to decrease in corrosion current densities of 316L stainless steel in physiological solutions. In addition, coated sample released much less ions such as Fe, Cr and Ni in physiological media. Therefore, it was concluded that Mg-substituted fluorapatite coatings could improve the corrosion resistance and biocompatibility of 316L stainless steel human body implants.

  18. A study of Ta xC 1 -x coatings deposited on biomedical 316L stainless steel by radio-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ding, M. H.; Wang, B. L.; Li, L.; Zheng, Y. F.

    2010-11-01

    In this paper, Ta xC 1 -x coatings were deposited on 316L stainless steel (316L SS) by radio-frequency (RF) magnetron sputtering at various substrate temperatures ( Ts) in order to improve its corrosion resistance and hemocompatibility. XRD results indicated that Ts could significantly change the microstructure of Ta xC 1 -x coatings. When Ts was <150 °C, the Ta xC 1 -x coatings were in amorphous condition, whereas when Ts was ≥150 °C, TaC phase was formed, exhibiting in the form of particulates with the crystallite sizes of about 15-25 nm ( Ts = 300 °C). Atomic force microscope (AFM) results showed that with the increase of Ts, the root-mean-square (RMS) values of the Ta xC 1 -x coatings decreased. The nano-indentation experiments indicated that the Ta xC 1 -x coating deposited at 300 °C had a higher hardness and modulus. The scratch test results demonstrated that Ta xC 1 -x coatings deposited above 150 °C exhibited good adhesion performance. Tribology tests results demonstrated that Ta xC 1 -x coatings exhibited excellent wear resistance. The results of potentiodynamic polarization showed that the corrosion resistance of the 316L SS was improved significantly because of the deposited Ta xC 1 -x coatings. The platelet adhesion test results indicated that the Ta xC 1 -x coatings deposited at Ts of 150 °C and 300 °C possessed better hemocompatibility than the coating deposited at Ts of 25 °C. Additionally, the hemocompatibility of the Ta xC 1 -x coating on the 316L SS was found to be influenced by its surface roughness, hydrophilicity and the surface energy.

  19. Multilayered Zr-C/a-C film on stainless steel 316L as bipolar plates for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Bi, Feifei; Peng, Linfa; Yi, Peiyun; Lai, Xinmin

    2016-05-01

    A multilayered zirconium-carbon/amorphous carbon (Zr-C/a-C) coating is synthesized by magnetron sputtering in order to improve the corrosion resistance and interfacial conductivity of stainless steel 316L (SS316L) as bipolar plates for proton exchange membrane fuel cells (PEMFCs). Zr-C/a-C film contains an outmost pure amorphous carbon layer and a sub zirconium containing carbon layer. Interfacial contact resistance (ICR) between carbon paper and coated SS316L decreases to 3.63 mΩ cm2 at 1.4 MPa. Potentiodynamic polarization results reveal that the corrosion potential of Zr-C/a-C coated sample is more positive than pure a-C coated sample and the current density is only 0.49 μA cm-2 at the cathode applied potential 0.6 V. Electrochemical impendence spectroscopy also indicates that multilayered Zr-C/a-C film coated SS316L has much higher charge transfer resistance than the bare sample. After potentiostatic polarization, ICR values are 3.92 mΩ cm2 and 3.82 mΩ cm2 in the simulated PEMFCs cathode and anode environment, respectively. Moreover, XPS analysis of the coated samples before and after potential holding tests shows little difference, which disclose the chemical stability of multilayered Zr-C/a-C film. Therefore, the multilayered Zr-C/a-C coating exhibits excellent performance in various aspects and is preferred for the application of stainless steel bipolar plates.

  20. COMPUTATION MODELING OF LOCALIZED CORROSION STABILITY ON WETTED SS316L AT 25 AND 95 DEGREE C

    SciTech Connect

    F. Cuti; F.J. Presuel-Moreno; R.G. Kelly

    2005-10-13

    For corrosion resistant materials exposed to low-temperature atmospheric environments, the corrosion mode of highest risk is expected to be localized corrosion (pitting, crevice, stress-corrosion cracking) due to accumulation of aggressive species within thin solution layers and/or formation of occluded local geometries. The stability of such a localized corrosion site requires that the corroding site (anode) must dissolve at a sufficient high rate to maintain the critical chemistry, and a robust cathodic area (cathode) must exist that can provide sufficient cathodic current. The characteristics of both the anode and the cathode depend on a large number of physiochemical variables (e.g., temperature, ionic concentration, water layer thickness, etc) and electrochemical parameters (i.e., cathodic and anodic polarization behavior). The effects of all these parameters add significantly to the dimensionality of the problem and a systematic study of these parameters is thus more tractable computationally than experimentally. The objective of this study was to computationally characterize the stability of such a local corrosion site and explore the effects of physiochemical and electrochemical parameters on that stability. The overall goal is to contribute to the establishment of a scientific basis for the prediction of the stabilization of localized attack on wetted, corrosion resistant material surface. A localized corrosion site, illustrated in Figure 1, consists of two parts: (a) the external wetted surface (cathode) and (b) the crevice (anode). This study computationally separated the two and modeled them individually, linking them through the imposition of a common fixed potential at the junction point (i.e., the mouth of the crevice). An objected-oriented computational code, CREVICER, developed at UVa, was extended to study separately both the wet surface (cathode) and the crevice (anode). SS316L was chosen as the material of interest.

  1. Effect of Surface Condition and Heat Treatment on Corrosion of Type 316L Stainless Steel in a Mercury Thermal Convection Loop

    SciTech Connect

    Pawel, S J

    2001-09-25

    Two thermal convection loops (TCLs) fabricated from 316L stainless steel and containing mercury and a variety of 316L coupons representing variable surface conditions and heat treatments have been operated continuously for 2000 h. Surface conditions included surface ground, polished, gold-coated, chemically etched, bombarded with Fe to simulate radiation damage, and oxidized. Heat treatments included solution treated, welded, and sensitized. In addition, a nitrogen doped 316L material, termed 316LN, was also examined in the solution treated condition. Duplicate TCLs were operated in this experiment--both were operated with a 305 C peak temperature, a 65 C temperature gradient, and mercury velocity of 1.2 m/min--but only one included a 36 h soak in Hg at 310 C just prior to operation to encourage wetting. Results indicate that the soak in Hg at 310 C had no lasting effect on wetting or compatibility with Hg. Further, based on examination of post-test wetting and coupon weight loss, only the gold-coated surfaces revealed significant interaction with Hg. In areas wetted significantly by Hg, the extreme surface of the stainless steel (ca 10 {micro}m) was depleted in Ni and Cr compared to the bulk composition.

  2. Effect of Surface Condition and Heat Treatment on Corrosion of Type 316L Stainless Steel in a Mercury Thermal Convection Loop

    SciTech Connect

    Pawel, S.J.

    2000-10-17

    Two thermal convection loops (TCLs) fabricated from 316L stainless steel and containing mercury and a variety of 316L coupons representing variable surface conditions and heat treatments have been operated continuously for 2000 h. Surface conditions included surface ground, polished, gold-coated, chemically etched, bombarded with Fe to simulate radiation damage, and oxidized. Heat treatments included solution treated, welded, and sensitized. In addition, a nitrogen doped 316L material, termed 316LN, was also examined in the solution treated condition. Duplicate TCLs were operated in this experiment--both were operated with a 305 C peak temperature, a 65 C temperature gradient, and mercury velocity of 1.2 m/min--but only one included a 36 h soak in Hg at 310 C just prior to operation to encourage wetting. Results indicate that the soak in Hg at 310 C had no lasting effect on wetting or compatibility with Hg. Further, based on examination of post-test wetting and coupon weight loss, only the gold-coated surfaces revealed significant interaction with Hg. In areas wetted significantly by Hg, the extreme surface of the stainless steel (ca 10 {micro}m) was depleted in Ni and Cr compared to the bulk composition.

  3. Evaluation of the soft tissue biocompatibility of MgCa0.8 and surgical steel 316L in vivo: a comparative study in rabbits

    PubMed Central

    2010-01-01

    Background Recent studies have shown the potential suitability of magnesium alloys as biodegradable implants. The aim of the present study was to compare the soft tissue biocompatibility of MgCa0.8 and commonly used surgical steel in vivo. Methods A biodegradable magnesium calcium alloy (MgCa0.8) and surgical steel (S316L), as a control, were investigated. Screws of identical geometrical conformation were implanted into the tibiae of 40 rabbits for a postoperative follow up of two, four, six and eight weeks. The tibialis cranialis muscle was in direct vicinity of the screw head and thus embedded in paraffin and histologically and immunohistochemically assessed. Haematoxylin and eosin staining was performed to identify macrophages, giant cells and heterophil granulocytes as well as the extent of tissue fibrosis and necrosis. Mouse anti-CD79α and rat anti-CD3 monoclonal primary antibodies were used for B- and T-lymphocyte detection. Evaluation of all sections was performed by applying a semi-quantitative score. Results Clinically, both implant materials were tolerated well. Histology revealed that a layer of fibrous tissue had formed between implant and overlying muscle in MgCa0.8 and S316L, which was demarcated by a layer of synoviocyte-like cells at its interface to the implant. In MgCa0.8 implants cavities were detected within the fibrous tissue, which were surrounded by the same kind of cell type. The thickness of the fibrous layer and the amount of tissue necrosis and cellular infiltrations gradually decreased in S316L. In contrast, a decrease could only be noted in the first weeks of implantation in MgCa0.8, whereas parameters were increasing again at the end of the observation period. B-lymphocytes were found more often in MgCa0.8 indicating humoral immunity and the presence of soluble antigens. Conversely, S316L displayed a higher quantity of T-lymphocytes. Conclusions Moderate inflammation was detected in both implant materials and resolved to a minimum

  4. In-vitro bioactivity, biocorrosion and antibacterial activity of silicon integrated hydroxyapatite/chitosan composite coating on 316 L stainless steel implants.

    PubMed

    Sutha, S; Kavitha, K; Karunakaran, G; Rajendran, V

    2013-10-01

    A simple and effective ultrasonication method was applied for the preparation of 0, 0.4, 0.8, 1.0 and 1.6 wt% silicon substituted hydroxyapatite (HAp) (SH). The Ca/P ratio of the synthesised SH nanoparticles were in the range of 1.58-1.70. Morphological changes were noticed in HAp with respect to the amount of Si from 0 to 1.6 wt%. The morphology of the particles changed from spherical shape to rod-like morphology with respect to the amount of Si which was confirmed using transmission electron microscopy. X-ray diffraction studies confirm the formation of phase pure SH nanoparticles without any secondary phase. Chitosan (CTS) blended SH nanocomposites coating on surgical grade 316 L stainless steel (316 L SS) implant was made by spin coating technique. The surface of the coated implant was characterised using scanning electron microscopy which confirms the uniform coating without cracks and pores. The increased corrosion resistance of the 1.6 wt% of SH/CTS-coated SS implant in the simulated body fluid (SBF) indicates the long-term biostability of SH composite-coated ceramics in vitro than the 0 wt% SH/CTS. The testing of SH/CTS nanocomposites with gram-positive and gram-negative bacterial strains confirms that the antibacterial ability improves with the higher substitution of Si. In addition, formation of bone-like apatite layer on the SH/CTS-coated implant in SBF was studied through SEM analysis and it confirms the ability to increase the HAp formation on the surface of 1.0 wt% SH/CTS-coated 316 L SS implant.

  5. In-vitro bioactivity, biocorrosion and antibacterial activity of silicon integrated hydroxyapatite/chitosan composite coating on 316 L stainless steel implants.

    PubMed

    Sutha, S; Kavitha, K; Karunakaran, G; Rajendran, V

    2013-10-01

    A simple and effective ultrasonication method was applied for the preparation of 0, 0.4, 0.8, 1.0 and 1.6 wt% silicon substituted hydroxyapatite (HAp) (SH). The Ca/P ratio of the synthesised SH nanoparticles were in the range of 1.58-1.70. Morphological changes were noticed in HAp with respect to the amount of Si from 0 to 1.6 wt%. The morphology of the particles changed from spherical shape to rod-like morphology with respect to the amount of Si which was confirmed using transmission electron microscopy. X-ray diffraction studies confirm the formation of phase pure SH nanoparticles without any secondary phase. Chitosan (CTS) blended SH nanocomposites coating on surgical grade 316 L stainless steel (316 L SS) implant was made by spin coating technique. The surface of the coated implant was characterised using scanning electron microscopy which confirms the uniform coating without cracks and pores. The increased corrosion resistance of the 1.6 wt% of SH/CTS-coated SS implant in the simulated body fluid (SBF) indicates the long-term biostability of SH composite-coated ceramics in vitro than the 0 wt% SH/CTS. The testing of SH/CTS nanocomposites with gram-positive and gram-negative bacterial strains confirms that the antibacterial ability improves with the higher substitution of Si. In addition, formation of bone-like apatite layer on the SH/CTS-coated implant in SBF was studied through SEM analysis and it confirms the ability to increase the HAp formation on the surface of 1.0 wt% SH/CTS-coated 316 L SS implant. PMID:23910313

  6. High-Temperature Oxidation Resistance of a Nanoceria Spray-Coated 316L Stainless Steel Under Short-Term Air Exposure

    NASA Astrophysics Data System (ADS)

    Lopez, Hugo F.; Mendoza, Humberto; Church, Ben

    2013-10-01

    Nanoceria coatings using a spray method were implemented on a 316L stainless steel (SS). Coated and uncoated coupons were exposed to dry air at 1073 K to 1273 K (800 °C to 1000 °C) for short time periods (up to 24 hours) and in situ measurements of oxidation were carried out using a highly sensitive thermogravimetric balance. From the experimental outcome, activation energies were determined in both, coated and uncoated 316 SS coupons. The estimated exhibited activation energies for oxidation in the coated and uncoated conditions were 174 and 356 kJ/mol, respectively. In addition, the developed scales were significantly different. In the coated steel, the dominant oxide was an oxide spinel (Fe, Mn)3O4 and the presence of Fe2O3 was sharply reduced, particularly at 1273 K (1000 °C). In contrast, no spinel was found in the uncoated 316L SS, and Fe2O3 was always present in the scale at all the investigated oxidation temperatures. The coated steels developed a highly adherent fine-grained scale structure. Apparently, the nanoceria particles enhanced nucleation of the newly formed scale while restricting coarsening. Coarse grain structures were found in the uncoated steels with scale growth occurring at grain ledges. Moreover, the oxidation rates for the coated 316L SS were at least an order of magnitude lower than those exhibited by the steel in the uncoated condition. The reduction in oxidation rates is attributed to a shift in the oxidation mechanism from outward cation diffusion to inward oxygen diffusion.

  7. Corrosion and microstructural analysis data for AISI 316L and AISI 347H stainless steels after exposure to a supercritical water environment

    PubMed Central

    Ruiz, A.; Timke, T.; van de Sande, A.; Heftrich, T.; Novotny, R.; Austin, T.

    2016-01-01

    This article presents corrosion data and microstructural analysis data of austenitic stainless steels AISI 316L and AISI 347H exposed to supercritical water (25 MPa, 550 °C) with 2000 ppb of dissolved oxygen. The corrosion tests lasted a total of 1200 h but were interrupted at 600 h to allow measurements to be made. The microstructural data have been collected in the grain interior and at grain boundaries of the bulk of the materials and at the superficial oxide layer developed during the corrosion exposure. PMID:27158647

  8. Infrared Brazing of Ti50Ni50 Shape Memory Alloy and 316L Stainless Steel with Two Sliver-Based Fillers

    NASA Astrophysics Data System (ADS)

    Shiue, Ren-Kae; Chen, Chia-Pin; Wu, Shyi-Kaan

    2015-06-01

    Dissimilar infrared brazing Ti50Ni50 and AISI 316L stainless steel using two silver-based fillers, Cusil-ABA and Ticusil, was evaluated. The shear strength of the Ticusil brazed joint is higher than that of the Cusil-ABA brazed one due to the formation of better fillet. The maximum shear strength of 237 MPa is obtained for the Ticusil joint brazed at 1223 K (950 °C) for 60 seconds. The presence of interfacial Ti-Fe-(Cu) layer is detrimental to the shear strength of all joints.

  9. Effect of Heat Treatment on the Microstructure and Mechanical Properties of Stainless Steel 316L Coatings Produced by Cold Spray for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    AL-Mangour, Bandar; Vo, Phuong; Mongrain, Rosaire; Irissou, Eric; Yue, Stephen

    2014-04-01

    In this study, the effects of heat treatment on the microstructure and mechanical properties of cold sprayed stainless steel 316L coatings using N2 and He as propellant gases were investigated. Powder and coating characterizations, including coating microhardness, coating porosity, and XRD phase analysis were performed. It was found that heat treatment reduced porosity, improved inter-particle bonding, and increased ductility. XRD results confirmed that no phase transformation occurred during deposition. Significant increase in UTS and ductility was observed for the annealed specimens obtained with nitrogen propellant, whereas little changes were observed for the helium propellant produced specimen.

  10. Laser surface texturing of 316L stainless steel in air and water: A method for increasing hydrophilicity via direct creation of microstructures

    NASA Astrophysics Data System (ADS)

    Razi, Sepehr; Madanipour, Khosro; Mollabashi, Mahmoud

    2016-06-01

    Laser processing of materials in water contact is sometimes employed for improving the machining, cutting or welding quality. Here, we demonstrate surface patterning of stainless steel grade 316L by nano-second laser processing in air and water. Suitable adjustments of laser parameters offer a variety of surface patterns on the treated targets. Furthermore alterations of different surface features such as surface chemistry and wettability are investigated in various processing circumstances. More than surface morphology, remarkable differences are observed in the surface oxygen content and wettability of the samples treated in air and water at the same laser processing conditions. Mechanisms of the changes are discussed extensively.

  11. Tritium and decay helium effects on the fracture toughness properties of types 316L, 304L and 21Cr-6Ni-9Mn stainless steels

    SciTech Connect

    Morgan, M.J.; Tosten, M.H

    1994-10-01

    J-integral fracture mechanics techniques and electron microscopy observations were used to investigate the effects of tritium and its radioactive decay product, {sup 3}He, on Types 316L, 304L and 21Cr-6Ni-9Mn stainless steels. Tritium-exposed-and-aged steels had lower fracture-toughness values and shallower sloped crack-growth-resistance curves than unexposed steels. Both fracture-toughness parameters decreased with increasing concentrations of {sup 3}He. The fracture-toughness reductions were accompanied by a change in fracture mode from microvoid-nucleation-and-growth processes in control samples to grain-and-twin-boundary fracture in tritium-charged-and-aged samples. Type 316L stainless steel had the highest fracture-toughness values and Type 21Cr-6Ni-9Mn had the lowest. Samples containing {sup 3}He but degassed of tritium had fracture toughness properties that were similar to uncharged samples. The results indicate that helium bubbles enhance the embrittlement effects of hydrogen by affecting the deformation properties and by increasing localized hydrogen concentrations through trapping effects.

  12. Effect of Heat Treatment on Low Temperature Toughness of Reduced Pressure Electron Beam Weld Metal of Type 316L Stainless Steel

    SciTech Connect

    Nakagawa, H.; Fujii, H.; Tamura, M.

    2006-03-31

    Austenitic stainless steels are considered to be the candidate materials for liquid hydrogen vessels and the related equipments, and those welding parts that require high toughness at cryogenic temperature. The authors have found that the weld metal of Type 316L stainless steel processed by reduced pressure electron beam (RPEB) welding has high toughness at cryogenic temperature, which is considered to be due to the single-pass welding process without reheating effect accompanied by multi-pass welding process.In this work, the effect of heat treatment on low temperature toughness of the RPEB weld metal of Type 316L was investigated by Charpy impact test at 77K. The absorbed energy decreased with higher temperature and longer holding time of heat treatment. The remarkable drop in the absorbed energy was found with heat treatment at 1073K for 2 hours, which is as low as that of conventional multi-pass weld metal such as tungsten inert gas welding. The observations of fracture surface and microstructure revealed that the decrease in the absorbed energy with heat treatment resulted from the precipitation of intermetallic compounds near delta-ferrite phase.

  13. Cultures and co-cultures of human blood mononuclear cells and endothelial cells for the biocompatibility assessment of surface modified AISI 316L austenitic stainless steel.

    PubMed

    Stio, Maria; Martinesi, Maria; Treves, Cristina; Borgioli, Francesca

    2016-12-01

    Samples of AISI 316L austenitic stainless steel were subjected either to grinding and polishing procedure, or to grinding and then low temperature glow-discharge nitriding treatment, or to grinding, nitriding and subsequently coating with collagen-I. Nitrided samples, even if only ground, show a higher corrosion resistance in PBS solution, in comparison with ground and polished AISI 316L. Biocompatibility was evaluated in vitro by incubating the samples with either peripheral blood mononuclear cells (PBMC) or human umbilical vein endothelial cells (HUVEC), tested separately or in co-culture. HUVEC-PBMC co-culture and co-incubation of HUVEC with PBMC culture medium, after the previous incubation of PBMC with metallic samples, allowed to determine whether the incubation of PBMC with the different samples might affect HUVEC behaviour. Many biological parameters were considered: cell proliferation, release of cytokines, matrix metalloproteinases (MMPs) and sICAM-1, gelatinolytic activity of MMPs, and ICAM-1 protein expression. Nitriding treatment, with or without collagen coating of the samples, is able to ameliorate some of the biological parameters taken into account. The obtained results point out that biocompatibility may be successfully tested in vitro, using cultures of normal human cells, as blood and endothelial cells, but more than one cell line should be used, separately or in co-culture, and different parameters should be determined, in particular those correlated with inflammatory phenomena. PMID:27612806

  14. Ion Beam Analysis, structure and corrosion studies of nc-TiN/a-Si3N4 nanocomposite coatings deposited by sputtering on AISI 316L

    NASA Astrophysics Data System (ADS)

    García, J.; Canto, C. E.; Flores, M.; Andrade, E.; Rodríguez, E.; Jiménez, O.; Solis, C.; de Lucio, O. G.; Rocha, M. F.

    2014-07-01

    In this work, nanocomposite coatings of nc-TiN/a-Si3N4, were deposited on AISI 316L stainless steel substrate by a DC and RF reactive magnetron co-sputtering technique using an A-N2 plasma. The structure of the coatings was characterized by means of XRD (X-ray Diffraction). The substrate and coating corrosion resistance were evaluated by potentiodynamic polarization using a Ringer solution as electrolyte. Corrosion tests were conducted with the purpose to evaluate the potential of this coating to be used on biomedical alloys. IBA (Ion Beam Analysis) techniques were applied to measure the elemental composition profiles of the films and, XPS (X-ray Photoelectron Spectroscopy) were used as a complementary technique to obtain information about the compounds present in the films. The nanocomposite coatings of nc-TiN/a-Si3N4 show crystalline (TiN) and amorphous (Si3N4) phases which confer a better protection against the corrosion effects compared with that of the AISI 316L.

  15. Reactive Wetting of an Iron-Base Superalloy MSA2020 and 316L Stainless Steel by Molten Zinc-Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Xu, Jing; Liu, Xingbo; Bright, Mark A.; Hemrick, James G.; Sikka, Vinod; Barbero, Ever

    2008-06-01

    The reactive wetting behaviors of MSA2020, an Fe-based superalloy, and 316L stainless steel in contact with a molten Zn-Al alloy were investigated by the sessile drop method. This investigation led to the following findings. (1) 316L not only suffered considerable wetting, but also reacted with the molten Zn-Al alloy at a higher rate than MSA2020. (2) The contact angle of MSA2020 wet by the molten Zn-Al alloy dropped to an acute angle when the temperature was increased to 500 °C. (3) The surface reaction was found to initiate even though the liquid droplet and substrate were observed as nonwetting (contact angle larger than 90 deg). (4) The reaction mechanisms were identified in three stages. Initially, the Al diffused into the substrate to form an Fe-aluminide layer, which acted as the reaction front. Next, the reaction front penetrated the substrate through inward diffusion of Al. Finally, Zn-rich zones formed behind the reaction front as a result of Al depletion. (5) The alloying constituents (W, Mo, and Cr) in MSA2020 stably segregating on the surface reduced the wettability by molten Zn-Al by covering the reactive sites on the solid-liquid interface.

  16. Electrochemical behavior of nanocrystalline Ta/TaN multilayer on 316L stainless steel: Novel bipolar plates for proton exchange membrane fuel-cells

    NASA Astrophysics Data System (ADS)

    Alishahi, M.; Mahboubi, F.; Mousavi Khoie, S. M.; Aparicio, M.; Hübner, R.; Soldera, F.; Gago, R.

    2016-08-01

    Insufficient corrosion resistance and surface conductivity are two main issues that plague large-scale application of stainless steel (SS) bipolar plates in proton exchange membrane fuel cells (PEMFCs). This study explores the use of nanocrystalline Ta/TaN multilayer coatings to improve the electrical and electrochemical performance of polished 316L SS bipolar plates. The multilayer coatings have been deposited by (reactive) magnetron sputtering and characterized by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy. The electrochemical behavior of bare and coated substrates has been evaluated in simulated PEMFC working environments by potentiodynamic and potentiostatic polarization tests at ambient temperature and 80 °C. The results show that the Ta/TaN multilayer coating increases the polarization resistance of 316L SS by about 30 and 104 times at ambient and elevated temperatures, respectively. The interfacial contact resistance (ICR) shows a low value of 12 mΩ × cm2 before the potentiostatic test. This ICR is significantly lower than for the bare substrate and remains mostly unchanged after potentiostatic polarization for 14 h. In addition, the high contact angle (92°) with water for coated substrates indicates a hydrophobic character, which can improve the water management within the cell in PEMFC stacks.

  17. Helium 3 precipitation in AISI 316L stainless steel induced by radioactive decay of tritium: Microstructural study of helium bubble precipitation

    NASA Astrophysics Data System (ADS)

    Brass, A. M.; Chanfreau, A.; Chene, J.

    1994-10-01

    This article deals with the study of the influence of thermomechanical heat treatments, aging conditions (temperature and time), and helium concentration on helium bubble precipitation in a 316L austenitic steel. Helium was generated by the radioactive decay of tritium (tritium trick). Helium bubbles impede the grain growth in 316L steel aged at 1373 K and also the recrystal-lization reaction at this temperature if cold working is performed prior to aging. Transmission electron microscopy (TEM) observations indicated a weak helium precipitation at 1073 and 1223 K, presumably due to the presence of trapping sites for tritium, and no bubble growth after aging up to 100 hours. Precipitation sites are mainly dislocations in the matrix at 1073 K and grain boundaries and individual dislocations in the matrix at 1223 K. The large bubble size (50 nm) observed at 1373 K, even for short aging times (0.083 hour), can partly be attributed to bubble dragging by dislocations toward the grain boundaries. Cold deformation prior to aging leads to a larger bubble size due to growth enhancement during recrystallization. Decreasing the helium content leads to a smaller helium bubble size and density. Tritium trapping at helium bubbles may favor helium 3 accumulation on defects such as grain boundaries, as observed by tritium autoradiography.

  18. Effect of Oxygen Content Upon the Microstructural and Mechanical Properties of Type 316L Austenitic Stainless Steel Manufactured by Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Cooper, Adam J.; Cooper, Norman I.; Dhers, Jean; Sherry, Andrew H.

    2016-09-01

    Although hot isostatic pressing (HIP) has been shown to demonstrate significant advances over more conventional manufacture routes, it is important to appreciate and quantify the detrimental effects of oxygen involvement during the HIP manufacture process on the microstructural and material properties of the resulting component. This paper quantifies the effects of oxygen content on the microstructure and Charpy impact properties of HIP'd austenitic stainless steel, through combination of detailed metallographic examination and mechanical testing on HIP'd Type 316L steel containing different concentrations (100 to 190 ppm) of oxygen. Micron-scale pores were visible in the microstructure of the HIP'd materials postmetallographic preparation, which result from the removal of nonmetallic oxide inclusions during metallographic preparation. The area fraction of the resulting pores is shown to correlate with the oxygen concentration which influences the Charpy impact toughness over the temperature range of 77 K to 573 K (-196 °C to 300 °C), and demonstrates the influence of oxygen involved during the HIP manufacture process on Charpy toughness. The same test procedures and microstructural analyses were performed on commercially available forged 316L. This showed comparatively fewer inclusions and exhibited higher Charpy impact toughness over the tested temperature range.

  19. Effect of Heat Treatment on Low Temperature Toughness of Reduced Pressure Electron Beam Weld Metal of Type 316L Stainless Steel

    NASA Astrophysics Data System (ADS)

    Nakagawa, H.; Fujii, H.; Tamura, M.

    2006-03-01

    Austenitic stainless steels are considered to be the candidate materials for liquid hydrogen vessels and the related equipments, and those welding parts that require high toughness at cryogenic temperature. The authors have found that the weld metal of Type 316L stainless steel processed by reduced pressure electron beam (RPEB) welding has high toughness at cryogenic temperature, which is considered to be due to the single-pass welding process without reheating effect accompanied by multi-pass welding process. In this work, the effect of heat treatment on low temperature toughness of the RPEB weld metal of Type 316L was investigated by Charpy impact test at 77K. The absorbed energy decreased with higher temperature and longer holding time of heat treatment. The remarkable drop in the absorbed energy was found with heat treatment at 1073K for 2 hours, which is as low as that of conventional multi-pass weld metal such as tungsten inert gas welding. The observations of fracture surface and microstructure revealed that the decrease in the absorbed energy with heat treatment resulted from the precipitation of intermetallic compounds near delta-ferrite phase.

  20. Effects of passive films on corrosion resistance of uncoated SS316L bipolar plates for proton exchange membrane fuel cell application

    NASA Astrophysics Data System (ADS)

    Yang, Ying; Ning, Xiaohui; Tang, Hongsheng; Guo, Liejin; Liu, Hongtan

    2014-11-01

    The effects of passive films on the corrosion behaviors of uncoated SS316L in anode and cathode environments of proton exchange membrane fuel cells (PEMFCs) are studied. Potentiodynamic and potentiostatic polarizations are employed to study the corrosion behavior; Mott-Schottky measurements are used to characterize the semiconductor properties of passive films; X-ray photoelectron spectroscopy (XPS) analyses are used to identify the compositions and the depth profiles of passive films. The passive films formed in the PEMFC anode and cathode environments under corresponding conditions both behave as n-type semiconductor. The passive film formed in the anode environment has a single-layer structure, Cr is the major element (Cr/Fe atomic ratio > 1), and the Cr/Fe atomic ratio decreases from the surface to the bulk; while the passive film formed in the PEMFC cathode environment has a bi-layer structure, Fe is the major element (Cr/Fe atomic ratio < 0.5), and in the external layer of the bi-layer structure Fe content increases rapidly and gradually in the internal layer. SS316L shows better corrosion resistance owing to both the high content of Cr oxide in the passive film and low band bending in normal PEMFC anode environments.

  1. Precipitation in AISI 316L(N) during creep tests at 550 and 600 °C up to 10 years

    NASA Astrophysics Data System (ADS)

    Padilha, A. F.; Escriba, D. M.; Materna-Morris, E.; Rieth, M.; Klimenkov, M.

    2007-05-01

    The precipitation behaviour in the gauge lengths and in the heads of initially solution annealed type 316L(N) austenitic stainless steel specimens tested in creep at 550 and 600 °C for periods of up to 85 000 h has been studied using several metallographic techniques. Three phases were detected: M 23C 6, Laves, and sigma phase. The volume fraction of the precipitated sigma phase was significantly higher than that of carbides and the Laves phase. M 23C 6 carbide precipitation occurred very rapidly and was followed by the sigma and Laves phases formation in the delta ferrite islands. Sigma and Laves phases precipitated at grain boundaries after longer times. Two different mechanisms of sigma phase precipitation have been proposed, one for delta ferrite decomposition and another for grain boundary precipitation. Small quantities of the Laves phase were detected in delta ferrite, at grain boundaries and inside the grains.

  2. Influence of Explosive-Driven Shock Prestraining on the Microstructural Evolution and Shear Localization of 304 and 316L Stainless Steels

    SciTech Connect

    Xue Qing; Cerreta, Ellen K.; Gray, George T. III

    2006-07-28

    Initiation and development of adiabatic shear bands in explosively pre-shocked 304 and 316L stainless steels was investigated to quantify the influence of shock prestraining on the onset of shear localization. Forced shear tests on hat-shaped specimens were conducted using a compressive split-Hopkinson pressure bar. The shear localized behavior under the forced shear condition in these preshocked materials was examined. Shear-band initiation was found to be very sensitive to the preshocked microstructures, especially to the strong interactions among defects such as deformation twin networks. The microstructures of shear bands were characterized using transmission electron microscopy(TEM). Dynamic and quasi-static recovery was verified to be a dominant mechanism in the formation of the ultra fine substructures within the shear bands generated in these preshocked steels.

  3. Evaluation of the Effect of Dynamic Sodium on the Low Cycle Fatigue Properties of 316L(N) Stainless Steel Base and Weld Joints

    NASA Astrophysics Data System (ADS)

    Ganesan, V.; Kannan, R.; Mariappan, K.; Sukumaran, G.; Sandhya, R.; Rao, K. Bhanu Sankara

    2012-06-01

    Low cycle fatigue (LCF) tests on 316L(N) austenitic stainless steel base and weld joints were at 823 K and 873 K at a constant strain rate of 3 × 10 -3 s -1 with strain ranges varying from {±}0.4% to {±}1.0% in a servo-hydraulic fatigue test system under flowing sodium environment. The cyclic stress response exhibited a similar trend as that in air comprising of an initial rapid hardening, followed by a slight softening stage before saturation. The fatigue lives are significantly improved in sodium environment when compared to identical testing conditions in air environment. The lack of oxidation in sodium environment is attributed to the delayed crack initiation, reduced crack propagation rate and consequent increase in fatigue life. Comparison of the data evaluated in sodium with RCC-MR design code, derived on the basis of data obtained from air shows that the design based on air tests is conservative.

  4. Corrosion behavior of TiN, TiAlN, TiAlSiN-coated 316L stainless steel in simulated proton exchange membrane fuel cell environment

    NASA Astrophysics Data System (ADS)

    Nam, Nguyen Dang; Vaka, Mahesh; Tran Hung, Nguyen

    2014-12-01

    To gain high hardness, good thermal stability and corrosion resistance, multicomponent TiAlSiN coating has been developed using different deposition methods. In this study, the influence of Al and Si on the electrochemical properties of TiN-coated 316L stainless steel as bipolar plate (BP) materials has been investigated in simulated proton exchange membrane fuel cell environment. The deposited TiN, TiAlN and TiAlSiN possess high hardness of 23.9, 31.7, 35.0 GPa, respectively. The coating performance of the TiN coating is enhanced by Al and Si addition due to lower corrosion current density and higher Rcoating and Rct values. This result could be attributed to the formation of crystalline-refined TiN(200), which improves the surface roughness, surface resistance, corrosion performance, and decreased passive current density.

  5. Electropolishing of Re-melted SLM Stainless Steel 316L Parts Using Deep Eutectic Solvents: 3 × 3 Full Factorial Design

    NASA Astrophysics Data System (ADS)

    Alrbaey, K.; Wimpenny, D. I.; Al-Barzinjy, A. A.; Moroz, A.

    2016-07-01

    This three-level three-factor full factorial study describes the effects of electropolishing using deep eutectic solvents on the surface roughness of re-melted 316L stainless steel samples produced by the selective laser melting (SLM) powder bed fusion additive manufacturing method. An improvement in the surface finish of re-melted stainless steel 316L parts was achieved by optimizing the processing parameters for a relatively environmentally friendly (`green') electropolishing process using a Choline Chloride ionic electrolyte. The results show that further improvement of the response value-average surface roughness ( Ra) can be obtained by electropolishing after re-melting to yield a 75% improvement compared to the as-built Ra. The best Ra value was less than 0.5 μm, obtained with a potential of 4 V, maintained for 30 min at 40 °C. Electropolishing has been shown to be effective at removing the residual oxide film formed during the re-melting process. The material dissolution during the process is not homogenous and is directed preferentially toward the iron and nickel, leaving the surface rich in chromium with potentially enhanced properties. The re-melted and polished surface of the samples gave an approximately 20% improvement in fatigue life at low stresses (approximately 570 MPa). The results of the study demonstrate that a combination of re-melting and electropolishing provides a flexible method for surface texture improvement which is capable of delivering a significant improvement in surface finish while holding the dimensional accuracy of parts within an acceptable range.

  6. Influence of cold plastic deformation on critical pitting potential of AISI 316 L and 304 L steels in an artificial physiological solution simulating the aggressiveness of the human body.

    PubMed

    Cigada, A; Mazza, B; Pedeferri, P; Sinigaglia, D

    1977-07-01

    The effect of cold working on critical pitting potential of AISI 316 L and 304 L steels in a buffered physiological solution has been studied. In particular, the importance of deformation degree, orientation of the specimen surface to the deformation direction, and cold working temperature in lowering the critical pitting potential is shown. PMID:873942

  7. SU-E-T-548: Modeling of Breast IORT Using the Xoft 50 KV Brachytherapy Source and 316L Steel Rigid Shield

    SciTech Connect

    Burnside, W

    2015-06-15

    Purpose: Xoft provides a set of 316L Stainless Steel Rigid Shields to be used with their 50 kV X-ray source for Breast IORT treatments. Modeling the different shield sizes in MCNP provides information to help make clinical decisions for selecting the appropriate shield size. Methods: The Xoft Axxent 50 kV Electronic Brachytherapy System has several applications in radiation therapy, one of which is treating cancer of the breast intraoperatively by placing the miniaturized X-ray tube inside an applicator balloon that is expanded to fill the lumpectomy bed immediately following tumor removal. The ribs, lung, and muscular chest wall are all regions at risk to receive undesired dose during the treatment. A Xoft 316L Stainless Steel Rigid Shield can be placed between the intracostal muscles of the chest wall and the remaining breast tissue near the balloon to attenuate the beam and protect these organs. These shields are provided in 5 different sizes, and the effects on dose to the surrounding tissues vary with shield size. MCNP was used to model this environment and tally dose rate to certain regions of interest. Results: The average rib dose rate calculated using 0cm (i.e., no shield), 3cm, and 5cm diameter shields were 26.89, 15.43, and 8.91 Gy/hr respectively. The maximum dose rates within the rib reached 94.74 Gy/hr, 53.56 Gy/hr, and 31.44 Gy/hr for the 0cm, 3cm, and 5cm cases respectively. The shadowing effect caused by the steel shields was seen in the 3-D meshes and line profiles. Conclusion: This model predicts a higher dose rate to the underlying rib region with the 3cm shield compared to the 5cm shield; it may be useful to select the largest possible diameter when choosing a shield size for a particular IORT patient. The ability to attenuate the beam to reduce rib dose was also confirmed. Research sponsored by Xoft Inc, a subsidiary of iCAD.

  8. The effect of CO2 laser beam welded AISI 316L austenitic stainless steel on the viability of fibroblast cells, in vitro.

    PubMed

    Köse, Ceyhun; Kaçar, Ramazan; Zorba, Aslı Pınar; Bağırova, Melahat; Allahverdiyev, Adil M

    2016-03-01

    It has been determined by the literature research that there is no clinical study on the in vivo and in vitro interaction of the cells with the laser beam welded joints of AISI 316L biomaterial. It is used as a prosthesis and implant material and that has adequate mechanical properties and corrosion resistance characteristics. Therefore, the interaction of the CO2 laser beam welded samples and samples of the base metal of AISI 316L austenitic stainless steel with L929 fibroblast cells as an element of connective tissue under in vitro conditions has been studied. To study the effect of the base metal and the laser welded test specimens on the viability of the fibroblast cells that act as an element of connective tissues in the body, they were kept in DMEMF-12 medium for 7, 14, 28 days and 18 months. The viability study was experimentally studied using the MTT method for 7, 14, 28 days. In addition, the direct interaction of the fibroblast cells seeded on 6 different plates with the samples was examined with an inverted microscope. The MTT cell viability experiment was repeated on the cells that were in contact with the samples. The statistical relationship was analyzed using a Tukey test for the variance with the GraphPad statistics software. The data regarding metallic ion release were identified with the ICP-MS method after the laser welded and main material samples were kept in cell culture medium for 18 months. The cell viability of the laser welded sample has been detected to be higher than that of the base metal and the control based on 7th day data. However, the laser welded sample's viability of the fibroblast cells has diminished by time during the test period of 14 and 28 days and base metal shows better viability when compared to the laser welded samples. On the other hand, the base metal and the laser welded sample show better cell viability effect when compared to the control group. According to the ICP-MS results of the main material and laser welded

  9. Effects of Ag and Cu ions on the microbial corrosion of 316L stainless steel in the presence of Desulfovibrio sp.

    PubMed

    Unsal, Tuba; Ilhan-Sungur, Esra; Arkan, Simge; Cansever, Nurhan

    2016-08-01

    The utilization of Ag and Cu ions to prevent both microbial corrosion and biofilm formation has recently increased. The emphasis of this study lies on the effects of Ag and Cu ions on the microbial corrosion of 316L stainless steel (SS) induced by Desulfovibrio sp. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used to analyze the corrosion behavior. The biofilm formation, corrosion products and Ag and Cu ions on the surfaces were investigated using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) and elemental mapping. Through circuit modeling, EIS results were used to interpret the physicoelectric interactions between the electrode, biofilm and culture interfaces. EIS results indicated that the metabolic activity of Desulfovibrio sp. accelerated the corrosion rate of SS in both conditions with and without ions. However, due to the retardation in the growth of Desulfovibrio sp. in the presence of Ag and Cu ions, significant decrease in corrosion rate was observed in the culture with the ions. In addition, SEM and EIS analyses revealed that the presence of the ions leads to the formation on the SS of a biofilm with different structure and morphology. Elemental analysis with EDS detected mainly sulfide- and phosphorous-based corrosion products on the surfaces. PMID:27105168

  10. Effect of Welding Current and Time on the Microstructure, Mechanical Characterizations, and Fracture Studies of Resistance Spot Welding Joints of AISI 316L Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kianersi, Danial; Mostafaei, Amir; Mohammadi, Javad

    2014-09-01

    This article aims at investigating the effect of welding parameters, namely, welding current and welding time, on resistance spot welding (RSW) of the AISI 316L austenitic stainless steel sheets. The influence of welding current and welding time on the weld properties including the weld nugget diameter or fusion zone, tensile-shear load-bearing capacity of welded materials, failure modes, energy absorption, and microstructure of welded nuggets was precisely considered. Microstructural studies and mechanical properties showed that the region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. Electron microscopic studies indicated different types of delta ferrite in welded nuggets including skeletal, acicular, and lathy delta ferrite morphologies as a result of nonequilibrium phases, which can be attributed to a fast cooling rate in the RSW process. These morphologies were explained based on Shaeffler, WRC-1992, and pseudo-binary phase diagrams. The optimum microstructure and mechanical properties were achieved with 8-kA welding current and 4-cycle welding time in which maximum tensile-shear load-bearing capacity or peak load of the welded materials was obtained at 8070 N, and the failure mode took place as button pullout with tearing from the base metal. Finally, fracture surface studies indicated that elongated dimples appeared on the surface as a result of ductile fracture in the sample welded in the optimum welding condition.

  11. Comparison between Palm Oil Derivative and Commercial Thermo-Plastic Binder System on the Properties of the Stainless Steel 316L Sintered Parts

    NASA Astrophysics Data System (ADS)

    Ibrahim, R.; Azmirruddin, M.; Wei, G. C.; Fong, L. K.; Abdullah, N. I.; Omar, K.; Muhamad, M.; Muhamad, S.

    2010-03-01

    Binder system is one of the most important criteria for the powder injection molding (PIM) process. Failure in the selection of the binder system will affect on the final properties of the sintered parts. The objectives of this studied is to develop a novel binder system based on the local natural resources and environmental friendly binder system from palm oil derivative which is easily available and cheap in our country of Malaysia. The novel binder that has been developed will be replaced the commercial thermo-plastic binder system or as an alternative binder system. The results show that the physical and mechanical properties of the final sintered parts fulfill the Metal Powder Industries Federation (MPIF) standard 35 for PIM parts. The biocompatibility test using cell osteosarcoma (MG63) and vero fibroblastic also shows that the cell was successfully growth on the sintered stainless steel 316L parts indicate that the novel binder was not toxic. Therefore, the novel binder system based on palm oil derivative that has been developed as a binder system fulfills the important criteria for the binder system in PIM process.

  12. Measurement methods for surface oxides on SUS 316L in simulated light water reactor coolant environments using synchrotron XRD and XRF

    NASA Astrophysics Data System (ADS)

    Watanabe, Masashi; Yonezawa, Toshio; Shobu, Takahisa; Shoji, Tetsuo

    2013-03-01

    Synchrotron X-ray diffraction (XRD) and X-ray fluorescent (XRF) measurement techniques have been used for non-destructive characterization of surface oxide films on Type 316L austenitic stainless steels that were exposed to simulated primary water environments of pressurized water reactors (PWR) and boiling water reactors (BWR). The layer structures of the surface spinel oxides were revealed ex situ after oxidation by measurements made as a function of depth. The layer structure of spinel oxides formed in simulated PWR primary water should normally be different from that formed in simulated BWR water. After oxidation in the simulated BWR environment, the spinel oxide was observed to contain NiFe2O4 at shallow depths, and FeCr2O4 and Fe3O4 at deeper depths. By contrast, after oxidation in the simulated PWR primary water environment, a Fe3O4 type spinel was observed near the surface and FeCr2O4 type spinel near the interface with the metal substrate. Furthermore, by in situ measurements during oxidation in the simulated BWR environment, it was also demonstrated that the ratio between spinel and hematite Fe2O3 can be changed depending on the water condition such as BWR normal water chemistry or BWR hydrogen water chemistry.

  13. Influence of LBE long term exposure and simultaneous fast neutron irradiation on the mechanical properties of T91 and 316L

    NASA Astrophysics Data System (ADS)

    Stergar, E.; Eremin, S. G.; Gavrilov, S.; Lambrecht, M.; Makarov, O.; Iakovlev, V.

    2016-05-01

    The LEXUR-II-LBE irradiation campaign was conducted from 2011 to 2012 and was aimed to investigate the combined influence of irradiation and LBE environment. In this irradiation campaign tensile test samples, pressurized tubes and corrosion samples were irradiated in LBE filled capsules. To separate the effect of exposure to LBE and neutron irradiation a parallel furnace experiment where the samples were exposed to LBE at the irradiation temperature for the corresponding time was conducted. Here we report results of the first extracted capsule which was irradiated about 6 months and dismantled after a cooling phase to decrease activity. The results of SSRT tests for irradiated T91 show that the exposure to LBE at 350 °C for a long time leads to the appearance of liquid metal embrittlement without any pre-treatment which is usually necessary to promote LME. Irradiation increases the effect of LME on the ductility of T91. In contrast to the findings for T91 the gained results also show that tensile tests on irradiated austenitic stainless steel 316L show no influence of LBE environment on the tensile properties.

  14. Laser deposited coatings of Co-Cr-Mo onto Ti-6Al-4V and SS316L substrates for biomedical applications.

    PubMed

    Wilson, J Michael; Jones, Nolan; Jin, Li; Shin, Yung C

    2013-10-01

    Functionally gradient bio-coating material was built by laser deposition. Co-Cr-Mo material was deposited on a Ti-6Al-4V substrate transitioning from 0% to 100%. Control over the cooling rate is shown to be a key to reduce the effects of thermal expansion differences of the materials. The microstructures and composition of the functionally gradient material (FGM) were characterized using an optical microscope, SEM, EDS, and XRD. EDS results showed a gradual transition to 50% Co-Cr-Mo and ∼100% Co-Cr-Mo on the top layer. XRD analysis showed the absence of a brittle intermetallic phase that forms between Titanium and Cobalt. As the amount of Co-Cr-Mo increased, the microhardness of the FGM samples significantly increased. A comparison was made between Co-Cr-Mo deposited on SS316L substrates as well as Ti-6Al-4V. The bonding strength of the coatings on both substrates was tested and found to meet the ASTM standard requirement.

  15. Effects of Ag and Cu ions on the microbial corrosion of 316L stainless steel in the presence of Desulfovibrio sp.

    PubMed

    Unsal, Tuba; Ilhan-Sungur, Esra; Arkan, Simge; Cansever, Nurhan

    2016-08-01

    The utilization of Ag and Cu ions to prevent both microbial corrosion and biofilm formation has recently increased. The emphasis of this study lies on the effects of Ag and Cu ions on the microbial corrosion of 316L stainless steel (SS) induced by Desulfovibrio sp. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used to analyze the corrosion behavior. The biofilm formation, corrosion products and Ag and Cu ions on the surfaces were investigated using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) and elemental mapping. Through circuit modeling, EIS results were used to interpret the physicoelectric interactions between the electrode, biofilm and culture interfaces. EIS results indicated that the metabolic activity of Desulfovibrio sp. accelerated the corrosion rate of SS in both conditions with and without ions. However, due to the retardation in the growth of Desulfovibrio sp. in the presence of Ag and Cu ions, significant decrease in corrosion rate was observed in the culture with the ions. In addition, SEM and EIS analyses revealed that the presence of the ions leads to the formation on the SS of a biofilm with different structure and morphology. Elemental analysis with EDS detected mainly sulfide- and phosphorous-based corrosion products on the surfaces.

  16. The effects of cold rolling orientation and water chemistry on stress corrosion cracking behavior of 316L stainless steel in simulated PWR water environments

    NASA Astrophysics Data System (ADS)

    Chen, Junjie; Lu, Zhanpeng; Xiao, Qian; Ru, Xiangkun; Han, Guangdong; Chen, Zhen; Zhou, Bangxin; Shoji, Tetsuo

    2016-04-01

    Stress corrosion cracking behaviors of one-directionally cold rolled 316L stainless steel specimens in T-L and L-T orientations were investigated in hydrogenated and deaerated PWR primary water environments at 310 °C. Transgranular cracking was observed during the in situ pre-cracking procedure and the crack growth rate was almost not affected by the specimen orientation. Locally intergranular stress corrosion cracks were found on the fracture surfaces of specimens in the hydrogenated PWR water. Extensive intergranular stress corrosion cracks were found on the fracture surfaces of specimens in deaerated PWR water. More extensive cracks were found in specimen T-L orientation with a higher crack growth rate than that in the specimen L-T orientation with a lower crack growth rate. Crack branching phenomenon found in specimen L-T orientation in deaerated PWR water was synergistically affected by the applied stress direction as well as the preferential oxidation path along the elongated grain boundaries, and the latter was dominant.

  17. Controlled electrophoretic deposition of HAp/β-TCP composite coatings on piranha treated 316L SS for enhanced mechanical and biological properties

    NASA Astrophysics Data System (ADS)

    Prem Ananth, K.; Nathanael, A. Joseph; Jose, Sujin P.; Oh, Tae Hwan; Mangalaraj, D.; Ballamurugan, A. M.

    2015-10-01

    Hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) bioactive materials have been used as individual coatings on steel implants employed in the fields of orthopedics and dentistry due to their excellent properties, which foster effective healing of the repair site. However, slow dissolution of HAp and fairly little fast dissolution of β-TCP present a major obstacle for such applications and this leads to the focus on the investigation of a mixture of HAp and β-TCP composite that forms biphasic calcium phosphate (BCP). The BCP coatings were achieved by thickness controlled electrophoretic deposition on piranha treated 316L SS. This method is well controlled and the anticipated dissolution rate could be attained with faster formation of new bone at the implant site, when compared to the individual HAp or β-TCP coating. The structural, functional, morphological and elemental composition of the coatings were characterized by using various analytical techniques. The BCP coating has been shown to have a role in obstructing the corrosion to a greater extent when in contact with SBF solution. The BCP coating also shows excellent in vitro and mechanical properties and osteoblasts cellular tests revealed that the coating was more effective in improving biocompatibility. This makes it an ideal candidate material for hard tissue replacement.

  18. The effect of synthetic scrubber solution chemistry on the corrosion behavior of type 316L stainless steel and Titanium Grade 2

    SciTech Connect

    Koch, G.H.; Beavers, J.A.; Whitman, L.

    1983-01-01

    A laboratory study was performed to investigate the effects of major solution variables of synthetic scrubber environments on the corrosion behavior of Type 316L Stainless Steel and Titanium Grade 2. The synthetic solution was calcium-based and contained magnesium, sodium, sulfate, chloride and fluoride. In solution preparation, it was found that the amount of sulfuric acid needed to achieve pH 1 was dependent on the chloride concentration. However, when the pH was adjusted to 1 prior to adding halides, the pH was found to decrease with increasing chloride concentration, whereas an increase in pH with increasing chloride concentration was observed when the initial pH was 4. When the pH was held constant, the corrosion rates of both the stainless steel and titanium decreased considerably with increasing chloride concentration above 30,000 ppm chloride. However, when the acid concentration was held constant, the corrosion rates of both alloys increased with increasing chloride concentration. Finally, corrosion rates decreased dramatically with increasing pH. An explanation of these observations is presented in terms of common ion effects and hydrogen ion activity.

  19. A study of the neutron irradiation effects on the susceptibility to embrittlement of A316L and T91 steels in lead bismuth eutectic

    NASA Astrophysics Data System (ADS)

    Sapundjiev, D.; Al Mazouzi, A.; Van Dyck, S.

    2006-09-01

    The effects of neutron irradiation on the susceptibility to liquid metal embrittlement of two primary selected materials for MYRRHA project an accelerator driven system (ADS), was investigated by means of slow strain rate tests (SSRT). The latter were carried out at 200 °C in nitrogen and in liquid Pb-Bi at a strain rate of 5 × 10 -6 s -1. The small tensile specimens were irradiated at the BR-2 reactor in the MISTRAL irradiation rig at 200 °C for 3 reactor cycles to reach a dose of about 1.50 dpa. The SSR tests were carried out under poor and under dissolved oxygen conditions (˜1.5 × 10 -12 wt% dissolved oxygen) which at this temperature will favour formation of iron and chromium oxides. Although both materials differ in structure (fcc for A316L against bcc for T91), their flow behaviour in contact with liquid lead bismuth eutectic before and after irradiation is very similar. Under these testing conditions none of them was found susceptible to liquid metal embrittlement (LME).

  20. A Microstructural Study on the Observed Differences in Charpy Impact Behavior Between Hot Isostatically Pressed and Forged 304L and 316L Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Cooper, Adam J.; Cooper, Norman I.; Bell, Andrew; Dhers, Jean; Sherry, Andrew H.

    2015-11-01

    With near-net shape technology becoming a more desirable route toward component manufacture due to its ability to reduce machining time and associated costs, it is important to demonstrate that components fabricated via Hot Isostatic Pressing (HIP) are able to perform to similar standards as those set by equivalent forged materials. This paper describes the results of a series of Charpy tests from HIP'd and forged 304L and 316L austenitic stainless steel, and assesses the differences in toughness values observed. The pre-test and post-test microstructures were examined to develop an understanding of the underlying reasons for the differences observed. The as-received microstructure of HIP'd material was found to contain micro-pores, which was not observed in the forged material. In tested specimens, martensite was detectable within close proximity to the fracture surface of Charpy specimens tested at 77 K (-196 °C), and not detected in locations remote from the fracture surface, nor was martensite observed in specimens tested at ambient temperatures. The results suggest that the observed changes in the Charpy toughness are most likely to arise due to differences in as-received microstructures of HIP'd vs forged stainless steel.

  1. Degradation of SS316L bipolar plates in simulated fuel cell environment: Corrosion rate, barrier film formation kinetics and contact resistance

    NASA Astrophysics Data System (ADS)

    Papadias, Dionissios D.; Ahluwalia, Rajesh K.; Thomson, Jeffery K.; Meyer, Harry M.; Brady, Michael P.; Wang, Heli; Turner, John A.; Mukundan, Rangachary; Borup, Rod

    2015-01-01

    A potentiostatic polarization method is used to evaluate the corrosion behavior of SS316L in simulated anode and cathode environments of polymer electrolyte fuel cells. A passive barrier oxide film is observed to form and reach steady state within ∼10 h of polarization, after which time the total ion release rates are low and nearly constant at ∼0.4 μg cm-2 h-1 for all potentials investigated. The equilibrium film thickness, however, is a function of the applied potential. The main ionic species dissolved in the liquid are predominately Fe followed by Ni, that account for >90% of the steady-state corrosion current. The dissolution rate of Cr is low but increases systematically at potentials higher than 0.8 V. The experimental ion release rates can be correlated with a point defect model using a single set of parameters over a broad range of potentials (0.2-1 V) on the cathode side. The interfacial contact resistance measured after 48 h of polarization is observed to increase with increase in applied potential and can be empirically correlated with applied load and oxide film thickness. The oxide film is substantially thicker at 1.5 V possibly because of alteration in film composition to Fe-rich as indicated by XPS data.

  2. Influences of deposition strategies and oblique angle on properties of AISI316L stainless steel oblique thin-walled part by direct laser fabrication

    NASA Astrophysics Data System (ADS)

    Wang, Xinlin; Deng, Dewei; Qi, Meng; Zhang, Hongchao

    2016-06-01

    Direct laser fabrication (DLF) developed from laser cladding and rapid prototyping technique has been widely used to fabricate thin-walled parts exhibiting more functions without expending weight and size. Oblique thin-walled parts accompanied with inhomogeneous mechanical properties are common in application. In the present study, a series of AISI316L stainless steel oblique thin-walled parts are successfully produced by DLF, in addition, deposition strategies, microstructure, and mechanical property of the oblique thin-walled parts are investigated. The results show that parallel deposition way is more valuable to fabricate oblique thin-walled part than oblique deposition way, because of the more remarkable properties. The hardness of high side initially increases until the distance to the substrate reaches about 25 mm, and then decreases with the increase of the deposition height. Oblique angle has a positive effect on the tensile property but a negative effect on microstructure, hardness and elongation due to the more tempering time. The maximum average ultimate tensile strength (UTS) and elongation are presented 744.3 MPa and 13.5% when the angle between tensile loading direction and horizontal direction is 45° and 90°, respectively.

  3. Influences of pH value, temperature, chloride ions and sulfide ions on the corrosion behaviors of 316L stainless steel in the simulated cathodic environment of proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Li, D. G.; Wang, J. D.; Chen, D. R.; Liang, P.

    2014-12-01

    316L stainless steel is in the passive state in a simulated cathodic environment, and the passivity of 316L SS is enhanced with increasing pH value, decreasing temperature, decreasing chloride ions and sulfide ions concentrations. Mott-Schottky plots show that the passive films appear a p-n heterojunction, and the donor and acceptor densities reach 1022 cm-3, showing a highly defective character of the passive film. The donor and acceptor densities increase with increasing temperature, increasing chloride ions and sulfide ions concentrations, while they decreased with increasing pH value. The decreased passivity and the increased doping density may be beneficial to the conductivity of the passive film, but they adversely affect the protectiveness of the passive film toward corrosion.

  4. Understanding the corrosion behavior of chromia-forming 316L stainless steel in dual oxidizing-reducing environment representative of SOFC interconnect

    SciTech Connect

    Ziomek-Moroz, Margaret; Cramer, Stephen D.; Holcomb, Gordon R.; Covino, Bernard S., Jr.; Matthes, Steven A.; Bullard, Sophie J.; Dunning, John S.; Alman, David E.; Singh, P.

    2003-11-01

    A and B site doped LaCrO3-based electronically conducting Perovskite ceramic materials have been extensively used as interconnects in solid oxide fule cells (SOFC) operating at 800° to 1000°C as the Perovskites offer good electrical conductivity, chemical compatibility with the adjacent components of the fuel cell, chemical stability in reducing and oxidizing atmospheres, and thermal expansion coefficients that match other cell components. However, requirements for good mechanical properties, electrical and thermal conductivities, and low cost make metallic interconnects more promising. Significant progress in reducing the operating temperature of SOFC from ~1000°C to ~750°C is expected to permit the use of metallic materials with substantial cost reduction. Among the commercially available metallic materials, Cr2O3 (chromia) scale-forming iron base alloys appear to be the most promising candidates since they can fulfill the technical and economical requirements. These alloys, however, remain prone to reactions with oxygen and water vapor at fuel cell operating conditions and formation of gaseous chromium oxides and oxyhydroxides. To study the degradation processes and corrosion mechanisms of commercial chromia scale-forming alloys under SOFC interconnect exposure conditions, 316L was selected for this research because of the availability of the materials. The dual environment to which the interconnect material was exposed consisted of dry air (simulates the cathode side environment) and a mixture of H2 and 3% H2O (simulates the anode side environment). Post-corrosion surface evaluation involved the use of optical and scanning electron microscopy, as well as energy dispersive X-ray analyses.

  5. A Comparative Evaluation of the Effect of Low Cycle Fatigue and Creep-Fatigue Interaction on Surface Morphology and Tensile Properties of 316L(N) Stainless Steel

    NASA Astrophysics Data System (ADS)

    Mariappan, K.; Shankar, Vani; Sandhya, R.; Bhaduri, A. K.; Laha, Kinkar

    2016-04-01

    In the present work, the deformation and damage evolution in 316L(N) stainless steel during low cycle fatigue (LCF) and creep-fatigue interaction (CFI) loadings have been compared by evaluating the residual tensile properties. Towards this, LCF and CFI experiments were carried out at constant strain amplitude of ±0.6 pct, strain rate of 3 × 10-3 s-1 and temperature of 873 K (600 °C). During CFI tests, 30 minutes hold period was introduced at peak tensile strain. Experiments were interrupted up to various levels of fatigue life viz. 5, 10, 30, 50, and 60 pct of the total fatigue life ( N f) under both LCF and CFI conditions. The specimens subjected to interrupted fatigue loadings were subsequently monotonically strained at the same strain rate and temperature up to fracture. Optical and scanning electron microscopy and profilometry were conducted on the untested and tested samples to elucidate the damage evolution during the fatigue cycling under both LCF and CFI conditions. The yield strength (YS) increased sharply with the progress of fatigue damage and attained saturation within 10 pct of N f under LCF condition. On the contrary, under CFI loading condition, the YS continuously increased up to 50 pct of N f, with a sharp increase of YS up to 5 pct of N f followed by a more gradual increase up to 50 pct of N f. The difference in the evolution of remnant tensile properties was correlated with the synergistic effects of the underlying deformation and damage processes such as cyclic hardening/softening, oxidation, and creep. The evolution of tensile properties with prior fatigue damage has been correlated with the change in surface roughness and other surface features estimated by surface replica technique and fractography.

  6. The Tribological Performance of Surface Treated Ti6A14V as Sliding Against Si3N4 Ball and 316L Stainless Steel Cylinder

    NASA Astrophysics Data System (ADS)

    Kao, W. H.; Su, Y. L.; Horng, J. H.; Huang, H. C.

    2016-10-01

    Closed field unbalanced magnetron sputtering was used to deposit diamond-like carbon (Ti-C:H) coatings on Ti6Al4V alloy and gas nitrided Ti6Al4V alloy. Four different specimens were prepared, namely untreated Ti6Al4V alloy (Ti6Al4V), gas nitrided Ti6Al4V alloy (N-Ti6Al4V), Ti-C:H-coated Ti6Al4V alloy (Ti-C:H/Ti6Al4V) and Ti-C:H-coated gas nitrided Ti6Al4V alloy (Ti-C:H/N-Ti6Al4V). The tribological properties of the four specimens were evaluated using a reciprocating wear tester sliding against a Si3N4 ball (point contact mode) and 316L stainless steel cylinder (line contact mode). The wear tests were performed in a 0.89 wt.% NaCl solution. The results showed that the nitriding treatment increased the surface roughness and hardness of the Ti6Al4V alloy and improved the wear resistance as a result. In addition, the Ti-C:H coating also improved the tribological performance of Ti6Al4V. For example, compared to the untreated Ti6Al4V sample, the Ti-C:H coating reduced the wear depth and friction coefficient by 340 times and 10 times, respectively, in the point contact wear mode, and 151 times and 9 times, respectively, in the line contact wear mode. It is thus inferred that diamond-like carbon coatings are of significant benefit in extending the service life of artificial biomedical implants.

  7. Effects of Mo content on microstructure and corrosion resistance of arc ion plated Ti-Mo-N films on 316L stainless steel as bipolar plates for polymer exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Kim, Kwang Ho; Shao, Zhigang; Wang, Feifei; Zhao, Shuang; Suo, Ni

    2014-05-01

    Bipolar plates are one of the most important components in PEMFC stack and have multiple functions, such as separators and current collectors, distributing reactions uniformly, and etc. Stainless steel is ideal candidate for bipolar plates owing to good thermal and electrical conductivity, good mechanical properties etc. However, stainless steel plate still cannot resist the corrosion of working condition. In this work, ternary Ti-Mo-N film was fabricated on 316L stainless steel (SS316L) as a surface modification layer to enhance the corrosion resistance. Effects of Mo content on the microstructure and corrosion resistance of Ti-Mo-N films are systematically investigated by altering sputtering current of the Mo target. XRD results reveal that the preferred orientation changes from [111] to [220] direction as Mo content in the film increases. The synthesized Ti-Mo-N films form a substitutional solid solution of (Ti, Mo)N where larger Mo atoms replace Ti in TiN crystal lattice. The TiN-coated SS316L sample shows the best corrosion resistance. While Mo content in the Ti-Mo-N films increases, the corrosion resistance gradually degrades. Compared with the uncoated samples, all the Ti-Mo-N film coated samples show enhanced corrosion resistance in simulated PEMFC working condition.

  8. Electrochemical behavior of the 316L steel type in a marine culture of microalgae (Porphyridium purpureum) under the 12/12 h photoperiod and effect of different working electrode exposure conditions on the biofilm-metal interface.

    PubMed

    Djemai-Zoghlache, Yamina; Isambert, Arsène; Belhaneche-Bensemra, Naima

    2011-12-01

    The industrial crops of microalgae use processes calling upon the presence of parts of metal nature such as steel 316L type. The goal of this study is to test the electrochemical behavior of this material in a marine culture of microalgae. Porphyridium purpureum was used under a photoperiod of alternation darkness/light 12/12 h, in order to apprehend the problems of biocorrosion involved in the biofouling. The evolution of the free potential of corrosion, according to the position of the samples and for different surface roughness, observations of the surface quality under the electron microscope with sweeping were carried out. The results showed that, overall, the strain P. purpureum does not have a corrosive effect on the 316L. The free potential of corrosion lies between -0.307 and -0.005 V(SCE). The adhesion of the cells seems stronger on the interface air/solid of the half-plunged sample with surface grit polished 1,000, confirmed by the presence of biofilm on the air part. The photoperiod acts on the evolution of the generated free potential of corrosion of the one 24-h period oscillation. Furthermore, the samples plunged horizontally lead to a stabilizing effect on the potential of free corrosion.

  9. Microstructural origins of radiation-induced changes in mechanical properties of 316 L and 304 L austenitic stainless steels irradiated with mixed spectra of high-energy protons and spallation neutrons

    NASA Astrophysics Data System (ADS)

    Sencer, B. H.; Bond, G. M.; Hamilton, M. L.; Garner, F. A.; Maloy, S. A.; Sommer, W. F.

    2001-07-01

    A number of candidate alloys were exposed to a particle flux and spectrum at Los Alamos Neutron Science Center (LANSCE) that closely match the mixed high-energy proton/neutron spectra expected in accelerator production of tritium (APT) window and blanket applications. Austenitic stainless steels 316 L and 304 L are two of these candidate alloys possessing attractive strength and corrosion resistance for APT applications. This paper describes the dose dependence of the irradiation-induced microstructural evolution of SS 316 L and 304 L in the temperature range 30-60°C and consequent changes in mechanical properties. It was observed that the microstructural evolution during irradiation was essentially identical in the two alloys, a behavior mirrored in their changes in mechanical properties. With one expection, it was possible to correlate all changes in mechanical properties with visible microstructural features. A late-term second abrupt decrease in uniform elongation was not associated with visible microstructure, but is postulated to be a consequence of large levels of retained hydrogen measured in the specimens. In spite of large amounts of both helium and hydrogen retained, approaching 1 at.% at the highest exposures, no visible cavities were formed, indicating that the gas atoms were either in solution or in subresolvable clusters.

  10. Corrosion Performance of Stainless Steels in a Simulated Launch Environment

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; Vinje, Rubiela D.; MacDowell, Louis

    2004-01-01

    At the Kennedy Space Center, NASA relies on stainless steel (SS) tubing to supply the gases and fluids required to launch the Space Shuttle. 300 series SS tubing has been used for decades but the highly corrosive environment at the launch pad has proven to be detrimental to these alloys. An upgrade with higher alloy content materials has become necessary in order to provide a safer and long lasting launch facility. In the effort to find the most suitable material to replace the existing AISI 304L SS ([iNS S30403) and AISI 316L SS (UNS S31603) shuttle tubing, a study involving atmospheric exposure at the corrosion test site near the launch pads and electrochemical measurements is being conducted. This paper presents the results of an investigation in which stainless steels of the 300 series, 304L, 316L, and AISI 317L SS (UNS S31703) as well as highly alloyed stainless steels 254-SMO (UNS S32154), AL-6XN (N08367) and AL29-4C ([iNS S44735) were evaluated using direct current (DC) electrochemical techniques under conditions designed to simulate those found at the Space Shuttle Launch pad. The electrochemical results were compared to the atmospheric exposure data and evaluated for their ability to predict the long-term corrosion performance of the alloys.

  11. Effect of Post-Weld Heat Treatment on Mechanical and Electrochemical Properties of Gas Metal Arc-Welded 316L (X2CrNiMo 17-13-2) Stainless Steel

    NASA Astrophysics Data System (ADS)

    Muhammad, F.; Ahmad, A.; Farooq, A.; Haider, W.

    2016-08-01

    In the present research work, corrosion behavior of post-weld heat-treated (PWHT) AISI 316L (X2CrNiMo 17-13-2) specimens joined by gas metal arc welding is compared with as-welded samples by using potentiodynamic polarization technique. Welded samples were PWHT at 1323 K for 480 s and quenched. Mechanical properties, corrosion behavior and microstructures of as-welded and PWHT specimens were investigated. Microstructural studies have shown grain size refinement after PWHT. Ultimate tensile strength and yield strength were found maximum for PWHT samples. Bend test have shown that PWHT imparted ductility in welded sample. Fractographic analysis has evidenced ductile behavior for samples. Potentiodynamic polarization test was carried out in a solution composed of 1 M H2SO4 and 1 N NaCl. Corrosion rate of weld region was 127.6 mpy, but after PWHT, it was decreased to 13.12 mpy.

  12. Effect of Post-Weld Heat Treatment on Mechanical and Electrochemical Properties of Gas Metal Arc-Welded 316L (X2CrNiMo 17-13-2) Stainless Steel

    NASA Astrophysics Data System (ADS)

    Muhammad, F.; Ahmad, A.; Farooq, A.; Haider, W.

    2016-10-01

    In the present research work, corrosion behavior of post-weld heat-treated (PWHT) AISI 316L (X2CrNiMo 17-13-2) specimens joined by gas metal arc welding is compared with as-welded samples by using potentiodynamic polarization technique. Welded samples were PWHT at 1323 K for 480 s and quenched. Mechanical properties, corrosion behavior and microstructures of as-welded and PWHT specimens were investigated. Microstructural studies have shown grain size refinement after PWHT. Ultimate tensile strength and yield strength were found maximum for PWHT samples. Bend test have shown that PWHT imparted ductility in welded sample. Fractographic analysis has evidenced ductile behavior for samples. Potentiodynamic polarization test was carried out in a solution composed of 1 M H2SO4 and 1 N NaCl. Corrosion rate of weld region was 127.6 mpy, but after PWHT, it was decreased to 13.12 mpy.

  13. A Study on the Laser Spatter and the Oxidation Reactions During Selective Laser Melting of 316L Stainless Steel, Al-Si10-Mg, and Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Simonelli, Marco; Tuck, Chris; Aboulkhair, Nesma T.; Maskery, Ian; Ashcroft, Ian; Wildman, Ricky D.; Hague, Richard

    2015-09-01

    The creation of an object by selective laser melting (SLM) occurs by melting contiguous areas of a powder bed according to a corresponding digital model. It is therefore clear that the success of this metal Additive Manufacturing (AM) technology relies on the comprehension of the events that take place during the melting and solidification of the powder bed. This study was designed to understand the generation of the laser spatter that is commonly observed during SLM and the potential effects that the spatter has on the processing of 316L stainless steel, Al-Si10-Mg, and Ti-6Al-4V. With the exception of Ti-6Al-4V, the characterization of the laser spatter revealed the presence of surface oxides enriched in the most volatile alloying elements of the materials. The study will discuss the implication of this finding on the material quality of the built parts.

  14. Electrochemical Evaluation of Stainless Steels in Acidified Sodium Chloride Solutions

    NASA Technical Reports Server (NTRS)

    Calle, L. M.; MacDowell, L. G.; Vinje, R. D.

    2004-01-01

    This paper presents the results of an investigation in which several 300-series stainless steels (SS): AISI S30403 SS (UNS S30403), AISI 316L SS (UNS S31603), and AISI 317L SS (LINS S31703), as well as highly-alloyed: SS 254-SMO (UNS S32154), AL-6XN (N08367) and AL29-4C (UNS S44735), were evaluated using DC electrochemical techniques in three different electrolyte solutions. The solutions consisted of neutral 3.55% NaCl, 3.55% NaCl in 0.1N HCl, and 3.55% NaCl in 1.0N HCl. These solutions were chosen to simulate environments that are less, similar, and more aggressive, respectively, than the conditions at the Space Shuttle launch pads. The electrochemical test results were compared to atmospheric exposure data and evaluated for their ability to predict the long-term corrosion performance of the subject alloys. The electrochemical measurements for the six alloys indicated that the higher-alloyed SS 254-SMO, AL29-4C, and AL-6XN exhibited significantly higher resistance to localized corrosion than the 300-series SS. There was a correlation between the corrosion performance of the alloys during a two-year atmospheric exposure and the corrosion rates calculated from electrochemical (polarization resistance) measurements.

  15. Corrosion and corrosion inhibition of metals/alloys in methylphosphonic difluoride and decontaminating solutions

    SciTech Connect

    Zabielski, C.V.; Levy, M.

    1994-12-31

    Binary munitions in which two different constituents are kept in separate compartments until activation will constitute a significant fraction of the chemical weapons in the United States. Because these munitions will be used under extreme circumstances, they must be stockpiled over very long periods of time (up to 30 years) and still be able to operate reliably when the need arises. A very high reliability of the storage container is essential to the subsequent activation of, and availability of, this weapon system. Electrochemical potentiodynamic polarization studies have been carried out for a variety of ferrous and nonferrous metals in methylphosphonic difluoride. Studies of the effect of organic inhibitors on the corrosion rate of 1020 steel (UNS G10200), 316L (UNS S31603), and 304 stainless steel (UNS S30400) and magnesium in methylphosphonic difluoride were also carried out. In addition, electrochemical studies were conducted in decontaminating solutions of sodium carbonate, organic/hydroxide and bleach. General corrosion rates are reported for ferrous alloys, titanium, aluminum alloys, magnesium, and two metal-matrix composites in full strength and diluted decontaminating solutions.

  16. Phorgotten phenomena: Galvanic corrosion remedy works -- but only if personnel know its intent

    SciTech Connect

    Dexter, S.C.

    1999-04-01

    Deep ocean instrumentation often is constructed from combinations of different materials as dictated by the necessary physical and mechanical properties as well as availability and cost. It is not at all uncommon for anodized aluminum alloys and stainless steels (SS) to be used in direct electrical contact, leading to the development of galvanic corrosion. In one case, a subsurface buoy was designed with a type 316L (UNS S31603) SS framework around a glass flotation sphere. Just before launch, a radio beacon and strobe light, used to locate the buoy when it was on the water surface, were attached directly to the framework with stainless U-bolts. The cylindrical housings for the radio beacon and strobe light were made of hard-anodized 6061-T6 aluminum (UNS A96061). Previous experience with these units deployed in the North Atlantic ocean for periods of a few months to 1 year showed that the beacon and strobe light stopped working prematurely because of corrosion of the anodized aluminum housings. The final remedy to protect the buoy against corrosion and the lessons learned are described.

  17. Proprietés mécaniques de surface d'un acier inoxydable traité par explosif

    NASA Astrophysics Data System (ADS)

    Paillé, L.; Gerland, M.; Villain, J. P.; Badawi, K. F.; Presles, H. N.; Bouchet, B.

    1994-02-01

    A new surface treatment technique by primary explosive was used on a 316L type austenitic stainless steel. Two explosive compositions, inducing a pressure of 1 GPa and 4 GPa respectively, were deposited in a thin layer on plane samples. The detonation induced effects have been characterized by different techniques. The surface roughness increases with the applied pressure, but remains lower than that obtained after shot peening. The microbardness profiles along a direction perpendicular to the treated surface and the microstructural study exhibit a marked hardening on several hundred micrometers associated with a profuse twinning. Moreover, for the 4 GPa pressure a very thin surface layer of fine recrystallized grains appears. In both cases, tensile residual stresses are measured at the surface and compressive stresses beyond 10~μm. The microstructure in the surface layers results of a noticeable thermal effect. The wear resistance of this stainless steel is improved by a factor 10 to 200 depending on the treatment conditions. Une technique de traitement de surface utilisant un explosif primaire a été utilisée sur un acier inoxydable austénitique de type 316L. Deux compositions explosives délivrant des pressions respectives de 1 GPa et 4 GPa ont été déposées en couche mince sur des échantillons plans. Les effets induits par la détonation ont été caractérisés par différentes techniques. La rugosité en surface augmente avec la pression appliquée mais reste très inférieure à celle obtenue après grenaillage. Les profils de microdureté suivant un axe perpendiculaire à la surface traitée et l'étude microstructurale montrent un écrouissage marqué sur quelques centaines de micromètres associé à un maclage important auquel s'ajoute, pour la pression de 4 GPa, une fine recristallisation en surface. Dans les deux cas, les contraintes résiduelles sont de tension en surface et passent en compression au-delà de 10~μm. La microstructure des

  18. Stability research on polydopamine and immobilized albumin on 316L stainless steel

    PubMed Central

    Xie, Lingxia; Deng, Jinchuan; Zhuang, Weihua; Luo, Rifang; Wang, Jin; Huang, Nan; Wang, Yunbing

    2016-01-01

    In this study, the polydopamine (PDA) film was coated on polished 316Lss and then thermally treated at 150 °C (labeled as PDA-Th150), and the stability of coatings was also investigated. Straining test indicated that PDA-Th150 coating performed better in affording sufficient adherence to 316 L SS substrate. Moreover, both PDA and PDA-Th150 coating suffered slight swelling during immersion in deionized water (pH = 6.5). X-ray photoelectron spectroscopy results showed that during immersion, latent nucleophilic reaction via amines inside PDA coating occurred. This led to an enhanced cross-linking and thus gradually promoted the coating stability. Moreover, larger amount of bovine serum albumin (BSA) was immobilized onto PDA-Th150 coating and performed well in anti-platelet adhesion. A high retention of immobilized BSA was observed even after immersion for 30 days. These tests suggested that PDA was stable enough and performed well in surface functionalization, which might enrich the research and application of PDA. PMID:27699058

  19. Stability research on polydopamine and immobilized albumin on 316L stainless steel

    PubMed Central

    Xie, Lingxia; Deng, Jinchuan; Zhuang, Weihua; Luo, Rifang; Wang, Jin; Huang, Nan; Wang, Yunbing

    2016-01-01

    In this study, the polydopamine (PDA) film was coated on polished 316Lss and then thermally treated at 150 °C (labeled as PDA-Th150), and the stability of coatings was also investigated. Straining test indicated that PDA-Th150 coating performed better in affording sufficient adherence to 316 L SS substrate. Moreover, both PDA and PDA-Th150 coating suffered slight swelling during immersion in deionized water (pH = 6.5). X-ray photoelectron spectroscopy results showed that during immersion, latent nucleophilic reaction via amines inside PDA coating occurred. This led to an enhanced cross-linking and thus gradually promoted the coating stability. Moreover, larger amount of bovine serum albumin (BSA) was immobilized onto PDA-Th150 coating and performed well in anti-platelet adhesion. A high retention of immobilized BSA was observed even after immersion for 30 days. These tests suggested that PDA was stable enough and performed well in surface functionalization, which might enrich the research and application of PDA.

  20. Surface nanostructuring of Ni, Ti, and 316L stainless steel using ultrafast laser interactions

    NASA Astrophysics Data System (ADS)

    Gill, Matt; Perrie, Walter; Fox, Peter; O'Neill, William

    2005-04-01

    The generation of surface periodic structures (SPS) on laser machined surfaces is known to occur when exciting the surface near the ablation threshold using short pulse laser exposure. These effects were first observed in the late 1960s and have remained a laboratory curiosity. Although well studied at nanosecond timescales there have been limited number of studies at ultrafast timescales. We have investigated the conditions necessary to generate short and long-range periodic structures using ultrafast laser pulses at λ =775nm and 387 nm which may find application in the field of surface engineering. This work examines the formation of SPS on a range of materials including Ni, Ti and SS316 and their dependence on fluence and polarisation.

  1. Comparative MRI compatibility of 316 L stainless steel alloy and nickel-titanium alloy stents.

    PubMed

    Holton, Andrea; Walsh, Edward; Anayiotos, Andreas; Pohost, Gerald; Venugopalan, Ramakrishna

    2002-01-01

    The initial success of coronary stenting is leading to a proliferation in peripheral stenting. A significant portion of the stents used in a clinical setting are made of 316 low carbon stainless steel (SS). Other alloys that have been used for stent manufacture include tantalum, MP35N, and nickel-titanium (NiTi). The ferromagnetic properties of SS cause the production of artifacts in magnetic resonance imaging (MRI). The NiTi alloys, in addition to being known for their shape memory or superelastic properties, have been shown to exhibit reduced interference in MRI. Thus, the objective of this study was to determine the comparative MRI compatibility of SS and NiTi stents. Both gradient echo and spin-echo images were obtained at 1.5 and 4.1 T field strengths. The imaging of stents of identical geometry but differing compositions permitted the quantification of artifacts produced due to device composition by normalizing the radio frequency shielding effects. These images were analyzed for magnitude and spatial extent of signal loss within the lumen and outside the stent. B1 mapping was used to quantify the attenuation throughout the image. The SS stent caused significant signal loss and did not allow for visibility of the lumen. However, the NiTi stent caused only minor artifacting and even allowed for visualization of the signal from within the lumen. In addition, adjustments to the flip angle of standard imaging protocols were shown to improve the quality of signal from within the lumen. PMID:12549230

  2. The role of deformation mechanisms in flow localization of 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Wu, Xianglin; Pan, Xiao; Mabon, James C.; Li, Meimei; Stubbins, James F.

    2006-09-01

    Type 316 SS is widely used as a structural material in a variety of current accelerator driven systems and designs as well as in a number of current and advanced fission and fusion reactor concepts. The material is found to be very sensitive to irradiation damage in the temperature range of 150-400 °C, where low levels of irradiation exposure, as little as 0.1 dpa, can substantially reduce the uniform elongation in tensile tests. This process, where the plastic flow becomes highly localized resulting in very low overall ductility, is referred to as flow localization. The process controlling this restriction of flow is related to the difference between the yield and ultimate strengths such that dramatic irradiation-induced increases in the yield strength results in very limited plastic flow until necking. In this study, the temperature dependence of this process is examined in light of the operating deformation mechanisms. It is found that twinning is an important deformation mechanism at lower temperatures but is not available in the temperature range of concern since the stress to activate twinning becomes excessively high. This limits the deformation and leads to the flow localization process.

  3. The passivity of Type 316L stainless steel in borate buffer solution

    NASA Astrophysics Data System (ADS)

    Nicic, Igor; Macdonald, Digby D.

    2008-09-01

    The passivity of Type 316 SS in borate buffer solution (pH 8.35), in the steady-state, has been explored using a variety of electrochemical techniques, including potentiostatic polarization, Mott Schottky analysis, and electrochemical impedance spectroscopy. The study shows that the passive film is an n-type semiconductor with a donor density that is essentially independent of voltage across the passive state. The passive current density is also found to be voltage-independent, but the thickness of the barrier layer depends linearly on the applied voltage. These observations are consistent with the predictions of the Point Defect Model, noting that the point defects within the barrier layer of the passive film are metal interstitials or oxygen vacancies, or both. No evidence for p-type behavior was obtained, indicating that cation vacancies do not have a significant population density in the film compared with the two donors (cation interstitials and oxygen vacancies).

  4. Mg-Doped Hydroxyapatite/Chitosan Composite Coated 316L Stainless Steel Implants for Biomedical Applications.

    PubMed

    Sutha, S; Dhineshbabu, N R; Prabhu, M; Rajendran, V

    2015-06-01

    In this investigation, ultrasonication process was used for the synthesis of magnesium doped nano-hydroxyapatite (MH) (0, 1, 2, and 3 mol% of Mg concentration) particles with controlled size and surface morphology. The size of the prepared MH particles was in the range of 20-100 nm with narrow distribution. Increase in the concentration of Mg reduced the particle size distribution from 60 to 40 nm. On incorporation of Mg in HAp lattice, an increase of 20-66 nm in specific surface area was observed in microporous HAp particles. XRF and XRD patterns reveal that the particles possess stoichiometric composition with reduced crystallinity with respect to the Mg concentration. Surface morphology of MH/chitosan (CTS) coated implant was found to be uniform without any defects. The corrosion rate of the implant decreased with increase in Mg concentration. The in vitro formation of bonelike apatite layer on the surface of the MH/CTS coated implant was observed from simulated body fluid studies. The antimicrobial activity of the MH/CTS composites against gram-positive and gram-negative bacterial strains indicated that increasing Mg concentration enhanced antimicrobial properties. Nanoindentation analysis of apatite coated implant surface reveals that the mechanical property depends on the concentration of magnesium in HAp. From the cytotoxicity analysis against NIH 3T3 fibroblast, it was observed that the Mg incorporated HAp/CTS composite was less toxic than the MHO/CTS composite. From this result, it was concluded that the MH/CTS nanocomposites coated implant is the excellent material for implants.

  5. Use of sputter-deposited 316L stainless steel ultrathin films for microbial influenced corrosion studies

    SciTech Connect

    Suci, P.A.; Geesey, G.G.; Pedraza, A.J.; Godbole, M.J.

    1993-12-31

    Ultra thin films (12nm) were sputter deposited onto cylindrical germanium internal reflection elements pre-coated with a thin (2 nm) layer of Cr{sub 2}O{sub 3}. Two crystals were inserted into Circle cell flow-through chambers and mounted on the optical bench of an Fourier Transform Infrared (FT-IR) spectrometer. One chamber was maintained as a sterile control while the other was sequentially inoculated with four bacterial species: Psudomonas aeruginosa, Bacillus subtillis, Hafnia alvei, and Desulfovibrio gigas, in that order. The water absorption band (1640cm{sup -4}) was monitored and used to follow that deterioration of the ultra thin films. In this respect, the sterile control and inoculated films exhibited only slight differences during the 1000h course of the experiment. Assay of the visible biofilm that has accumulated on the surface of the inoculated crystal after 1000h revealed that the film incorporated viable cells from all four strains.

  6. Gradient titanium and silver based carbon coatings deposited on AISI316L

    NASA Astrophysics Data System (ADS)

    Batory, Damian; Reczulska, Malgorzata Czerniak-; Kolodziejczyk, Lukasz; Szymanski, Witold

    2013-06-01

    The constantly growing market for medical implants and devices caused mainly due to a lack of proper attention attached to the physical condition as well as extreme sports and increased elderly population creates the need of new biocompatible biomaterials with controlled bioactivity and certain useful properties. According to many literature reports, regarding the modifications of variety of different biomaterials using the surface engineering techniques and their biological and physicochemical examination results, the most promising material for great spectra of medical applications seem to be carbon layers. Another issue is the interaction between the implant material and surrounding tissue. In particular cases this interface area is directly exposed to air. Abovementioned concern occurs mainly in case of the external fixations, thus they are more vulnerable to infection. Therefore a crucial role has the inhibition of bacterial adhesion that may prevent implant-associated infections, occurrence of other numerous complications and in particular cases rejection of the implant. For this reason additional features of carbon coatings like antibacterial properties seem to be desired and justified. Silver doped diamond-like carbon coatings with different Ag concentrations were prepared by hybrid RF PACVD/MS (Radio Frequency Plasma Assisted Chemical Vapor Deposition/Magnetron Sputtering) deposition technique. Physicochemical parameters like chemical composition, morphology and surface topography, hardness and adhesion were determined. Examined layers showed a uniform distribution of silver in the amorphous DLC matrix, high value of H/E ratio, good adhesion and beneficial topography which make them a perfect material for medical applications e.g. modification of implants for the external fixations.

  7. The UN's water torture.

    PubMed

    Miller, Henry I

    2010-01-01

    The United Nations is a bastion of corruption, profligacy and incompetence that is a particular threat to the inhabitants of poor nations. Its policies, programs and agencies have made a growth industry of the unscientific regulation of important technologies-of which gene-splicing [also known as recombinant DNA technology or genetic modification (GM)] is only one. The UN's actions regularly defy scientific consensus and common sense, instead pandering to extremists. The result is vastly inflated research and development costs, less innovation, and diminished exploitation of superior techniques and products that could offer monumental humanitarian and economic benefits.

  8. Tiempo para un cambio

    NASA Astrophysics Data System (ADS)

    Woltjer, L.

    1987-06-01

    En la reunion celebrada en diciembre dei ano pasado informe al Consejo de mi deseo de terminar mi contrato como Director General de la ESO una vez que fuera aprobado el proyecto dei VLT, que se espera sucedera hacia fines de este aAo. Cuando fue renovada mi designacion hace tres aAos, el Consejo conocia mi intencion de no completar los cinco aAos dei contrato debido a mi deseo de disponer de mas tiempo para otras actividades. Ahora, una vez terminada la fase preparatoria para el VLT, Y habiendose presentado el proyecto formalmente al Consejo el dia 31 de marzo, y esperando su muy probable aprobacion antes dei termino de este ano, me parece que el 10 de enero de 1988 presenta una excelente fecha para que se produzca un cambio en la administracion de la ESO.

  9. An XPS study of passive films on stainless steels and a high-grade Ni-base alloy in seawater environments

    SciTech Connect

    Hodgkiess, T.; Neville, A.

    1999-11-01

    In the present study an assessment has been made of the air-formed passive film and the passive film existing after a short exposure to a synthetic seawater environment on austenitic (UNS S31603), superaustenitic (UNS S31254 and UNS S32654) and superduplex (UNS S32760) stainless steels and a Ni-based alloy (UNS N06625) using X-Ray Photoelectron Spectroscopy (XPS). Assessment of their corrosion behavior has been made through use of electrochemical accelerated tests supported by post-test microscopy. The passive film on the Ni-base (low Fe) UNS N06625 alloy is remarkably similar to those formed on the high Cr and Mo stainless steels. It has been demonstrated that the Fe/Cr ratio in the passive film is dependent on alloy composition and on the conditions to which the material has been exposed and a general correlation between passive film constitution and corrosion resistance is evident.

  10. Initial stage sintering model of 316L stainless steel with application to three dimensionally printed (3DP(TM)) components

    NASA Astrophysics Data System (ADS)

    Johnston, Scott R.

    The design phase of manufacturing has become increasingly dependent upon computers for geometric and functional analysis of design concepts [1]. The ability to manufacture final components directly from computer images has been made possible by recent developments in rapid prototyping technologies and improvements in material processing, namely rapid manufacturing. Three Dimensional Printing (3DP(TM)) is a powder metallurgical rapid pro-totyping technique that incorporates initial stage sintering within the rapid manufacturing process. Initial stage sintering is characterized by neck growth between powder particles resulting in a light cohesive strengthening bond while preserving dimensionality. This study involved a detailed look into the theoretical mechanisms that produce material transport via diffusion methods to produce a quantitative dimensional sintering strain model. Here, we modify the accepted isothermal theoretical model describing initial stage sintering presented by German [2] and Ashby [3] to support a non-isothermal load history. Isothermal theoretical models have defined sintering in terms of surface and bulk mechanisms, where literature assumes that surface mechanisms do not produce interparticle approach for the ideal two-particle geometry. An expansion of the two-particle neck geometry from isothermal sintering theory to non-isothermal is performed by defining both the neck geometry and sintering mechanisms in terms of three geometric parameters. A quantitative sintering model is developed by introducing a volume constraint on the geometry and enforcing the assumption that surface sintering mechanisms do not produce inter-particle approach (no sintering strain). The sintering model produces quantitative strain results which are accurate to within 20% experimentally obtained final sintering strains. A qualitative strength model based on empirical data is also developed based on the amount of the final sintering strain. Modeling efforts were supported by several sets of experimentation. Initial experimental results indicate that the anisotropic manufacturing of 3DP(TM) components result with orthotropic sintering strain development. Particle diameter experimentation revealed that components comprised of small particles (20mum) experienced more strain than components comprised of large particles (200mum). Strength experimentation showed two different types of mechanical responses from load-deflection measurements, where specimens with less sintering strain exhibited a brittle response and specimens with more sintering strain experienced plastic deformation.

  11. Comparative study of the native oxide on 316L stainless steel by XPS and ToF-SIMS

    SciTech Connect

    Tardio, Sabrina Abel, Marie-Laure; Castle, James E.; Watts, John F.; Carr, Robert H.

    2015-09-15

    The very thin native oxide film on stainless steel, of the order of 2 nm, is known to be readily modified by immersion in aqueous media. In this paper, X-ray photoelectron spectroscopy (XPS) and time of flight secondary ions mass spectrometry are employed to investigate the nature of the air-formed film and modification after water emersion. The film is described in terms of oxide, hydroxide, and water content. The preferential dissolution of iron is shown to occur on immersion. It is shown that a water absorbed layer and a hydroxide layer are present above the oxide-like passive film. The concentrations of water and hydroxide appear to be higher in the case of exposure to water. A secure method for the peak fitting of Fe2p and Cr2p XPS spectra of such films on their metallic substrates is described. The importance of XPS survey spectra is underlined and the feasibility of C{sub 60}{sup +} SIMS depth profiling of a thin oxide layer is shown.

  12. Parameters optimization of hybrid fiber laser-arc butt welding on 316L stainless steel using Kriging model and GA

    NASA Astrophysics Data System (ADS)

    Gao, Zhongmei; Shao, Xinyu; Jiang, Ping; Cao, Longchao; Zhou, Qi; Yue, Chen; Liu, Yang; Wang, Chunming

    2016-09-01

    It is of great significance to select appropriate welding process parameters for obtaining optimal weld geometry in hybrid laser-arc welding. An integrated optimization approach by combining Kriging model and GA is proposed to optimize process parameters. A four-factor, five-level experiment using Taguchi L25 is conducted considering laser power (P), welding current (A), distance between laser and arc (D) and traveling speed (V). Kriging model is adopted to approximate the relationship between process parameters and weld geometry, namely depth of penetration (DP), bead width (BW) and bead reinforcement (BR). The constructed Kriging model was used for parameters optimization by GA to maximize DP, minimize BW and ensure BR at a desired value. The effects of process parameters on weld geometry are analyzed. Microstructure and micro-hardness are also discussed. Verification experiments demonstrate that the obtained optimum values are in good agreement with experimental results.

  13. Localized effects of macrofouling species on electrochemical corrosion of high grade alloys

    SciTech Connect

    Hodgkiess, T.; Nevilie, A.

    1998-12-31

    Interactions between macrofouling and corrosion on some stainless steels, UNS N06625 and UNS R30006 have been studied in long-term tests conducted in natural seawater off the west coast of Scotland. After a 18-month exposure period, the specimens were heavily fouled primarily with barnacles and mussels and all the materials exhibited crevice corrosion although this was less extensive on the Ni-base alloy. Localized corrosion was observed under the base of live barnacles on UNS S31603 stainless steel. DC electrochemical anodic polarization tests undertaken after the 18-month exposure period, yielded unusually high currents in the range of potential between the free corrosion value and the breakdown potential. This observation was associated with the appearance, after the anodic polarization, of black sulfide corrosion products at the specimen/resin crevices, around barnacles and around mussel byssus threads.

  14. UN COPUOS Space Debris Guidelines

    NASA Astrophysics Data System (ADS)

    Portelli, Claudio

    The Space systems today provide growing benefits to enhance the quality of humankind. However as a by product, the orbiting objects inevitably leaves some debris which after 50 years of space activities represent a concern for all space agencies and manufacturers and operators. Since last year no international agreement was in place to mitigate the growing population of space debris objects. The successful result obtained at UN COPUOS in 2007 and available in the OOSA web site, now gives to the public, a set of voluntary international guidelines that could, if adopted by each space fairing Country, help in maintaining the present space environment. More further steps are necessary in the future to define a legal and normative framework. The paper will present the seven established UN Space Debris guidelines as well as examples of the minimum steps to be carried out at national level to enable the UN COPUOS to start the discussion of the legal aspect associated with the space debris issue.

  15. Transfert radiatif numerique pour un code SPH

    NASA Astrophysics Data System (ADS)

    Viau, Joseph Edmour Serge

    2001-03-01

    Le besoin de reproduire la formation d'etoiles par simulations numeriques s'est fait de plus en plus present au cours des 30 dernieres annees. Depuis Larson (1968), les codes de simulations n'ont eu de cesse de s'ameliorer. D'ailleurs, en 1977, Lucy introduit une autre methode de calcul venant concurrencer la methode par grille. Cette nouvelle facon de calculer utilise en effet des points a defaut d'utiliser des grilles, ce qui est une bien meilleure adaptation aux calculs d'un effondrement gravitationnel. Il restait cependant le probleme d'ajouter le transfert radiatif a un tel code. Malgre la proposition de Brookshaw (1984), qui nous montre une formule permettant d'ajouter le transfert radiatif sous la forme SPH tout en evitant la double sommation genante qu'elle implique, aucun code SPH a ce jour ne contient un transfert radiatif satisfaisant. Cette these presente pour la premiere fois un code SPH muni d'un transfert radiatif adequat. Toutes les difficultes ont pu etre surmontees afin d'obtenir finalement le transfert radiatif "vrai" qui survient dans l'effondrement d'un nuage moleculaire. Pour verifier l'integrite de nos resultats, une comparaison avec le nonisothermal test case de Boss & Myhill (1993) nous revele un resultat fort satisfaisant. En plus de suivre fidelement la courbe de l'evolution de la temperature centrale en fonction de la densite centrale, notre code est exempt de toutes les anomalies rencontrees par les codes par grille. Le test du cas de la conduction thermique nous a lui aussi servit a verifier la fiabilite de notre code. La aussi les resultats sont fort satisfaisants. Faisant suite a ces resultats, le code fut utilise dans deux situations reelles de recherche, ce qui nous a permis de demontrer les nombreuses possibilites que nous donne notre nouveau code. Dans un premier temps, nous avons tudie le comportement de la temperature dans un disque d'accretion durant son evolution. Ensuite nous avons refait en partie une experience de Bonnell

  16. Analysis of structure and deformation behavior of AISI 316L tensile specimens from the second operational target module at the Spallation Neutron Source

    DOE PAGES

    Gussev, Maxim N.; McClintock, David A.; Garner, Frank

    2015-08-05

    In an earlier publication, tensile testing was performed on specimens removed from the first two operational targets of the Spallation Neutron Source (SNS). There were several anomalous features in the results. First, some specimens had very large elongations (up to 57%) while others had significantly smaller values. Second, there was a larger than the usual amount of data scatter in the elongation results. Third, the stress-strain diagrams of nominally similar specimens spanned a wide range of behavior ranging from expected irradiation-induced hardening to varying levels of force drop after yield point and indirect signs of "traveling deformation wave" behavior associatedmore » with strain-induced martensite formation. To investigate the cause(s) of such variable tensile behavior, several specimens from Target 2, spanning the range of observed tensile behavior, were chosen for detailed microstructural examination using electron backscattering analysis (EBSD). It was also shown that the steel employed in the construction of the target contained an unexpected bimodal grain size distribution, containing very large out-of-specification grains surrounded by necklaces of grains of within-specification sizes. The large grains were frequently comparable to the width of the gauge section of the tensile specimen. Moreover, the propensity to form martensite during deformation was shown to be accelerated by radiation but also to be very sensitive to the relative orientation of the grains with respect to the tensile axis. Specimens having large grains in the gauge that were most favorably oriented for production of martensite strongly exhibited the traveling deformation wave phenomenon, while those specimens with less favorably oriented grains had lesser or no degree of the wave effect, thereby accounting for the larger than expected data scatter.« less

  17. Analysis of structure and deformation behavior of AISI 316L tensile specimens from the second operational target module at the Spallation Neutron Source

    SciTech Connect

    Gussev, Maxim N.; McClintock, David A.; Garner, Frank

    2015-08-05

    In an earlier publication, tensile testing was performed on specimens removed from the first two operational targets of the Spallation Neutron Source (SNS). There were several anomalous features in the results. First, some specimens had very large elongations (up to 57%) while others had significantly smaller values. Second, there was a larger than the usual amount of data scatter in the elongation results. Third, the stress-strain diagrams of nominally similar specimens spanned a wide range of behavior ranging from expected irradiation-induced hardening to varying levels of force drop after yield point and indirect signs of "traveling deformation wave" behavior associated with strain-induced martensite formation. To investigate the cause(s) of such variable tensile behavior, several specimens from Target 2, spanning the range of observed tensile behavior, were chosen for detailed microstructural examination using electron backscattering analysis (EBSD). It was also shown that the steel employed in the construction of the target contained an unexpected bimodal grain size distribution, containing very large out-of-specification grains surrounded by necklaces of grains of within-specification sizes. The large grains were frequently comparable to the width of the gauge section of the tensile specimen. Moreover, the propensity to form martensite during deformation was shown to be accelerated by radiation but also to be very sensitive to the relative orientation of the grains with respect to the tensile axis. Specimens having large grains in the gauge that were most favorably oriented for production of martensite strongly exhibited the traveling deformation wave phenomenon, while those specimens with less favorably oriented grains had lesser or no degree of the wave effect, thereby accounting for the larger than expected data scatter.

  18. Synthesis of thoria nano-particles at low temperature through base electrogeneration on steel 316L surface: Effect of current density

    NASA Astrophysics Data System (ADS)

    Yousefi, Taher; Torab-Mostaedi, Meisam; Mobtaker, Hossein Ghasemi; Keshtkar, Ali Reza

    2016-10-01

    The strategy developed in this study, offers significant advantages (simplicity and cleanness of method and also a product purity and new morphology of the product) over the conventional routes for the synthesis of ThO2 nanostructure. The effect of current density on morphology was studied. The synthesized powder was characterized by means of Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM, Phillips EM 2085) Brunauer-Emmett-Teller (BET) and Fourier Transform Infrared (FT-IR) spectroscopy. The results show that the current density has a great effect on the morphology of the samples. The average size of the particles decreases as the applied current density increases and the average size of the samples decreases from 50 to 15 nm when the current density increases from 2 to 5 mA cm-2.

  19. Improved corrosion resistance and interfacial contact resistance of 316L stainless-steel for proton exchange membrane fuel cell bipolar plates by chromizing surface treatment

    NASA Astrophysics Data System (ADS)

    Lee, S. B.; Cho, K. H.; Lee, W. G.; Jang, H.

    The electrochemical performance and electrical contact resistance of chromized 316 stainless-steel (SS) are investigated under simulated operating condition in a proton-exchange membrane fuel cell (PEMFC). The corrosion resistance of the chromized stainless steel is assessed by potentiodynamic and potentiostatic tests and the interfacial contact resistance (ICR) is examined by measuring the electrical contact resistance as a function of the compaction force. The results show that the chromizing surface treatment improves the corrosion resistance of the stainless steel due to the high-chromium concentration in the diffuse coating layer. On the other hand, the excess Chromium content on the surface increases the contact resistance of the steel plate to a level that is excessively high for commercial applications. This study examines the root cause of the high-contact resistance after chromizing and reports the optimum process to improve the corrosion resistance without sacrificing the ICR by obtaining a chrome carbide on the outer layer.

  20. Analysis of structure and deformation behavior of AISI 316L tensile specimens from the second operational target module at the Spallation Neutron Source

    NASA Astrophysics Data System (ADS)

    Gussev, M. N.; McClintock, D. A.; Garner, F. A.

    2016-01-01

    In an earlier publication, tensile testing was performed on specimens removed from the first two operational targets of the Spallation Neutron Source (SNS). There were several anomalous features in the results. First, some specimens had very large elongations (up to 57%) while others had significantly smaller values (10-30%). Second, there was a larger than the usual amount of data scatter in the elongation results. Third, the stress-strain diagrams of nominally similar specimens spanned a wide range of behavior ranging from expected irradiation-induced hardening to varying levels of force drop after yield point and indirect signs of "traveling deformation wave" behavior associated with strain-induced martensite formation. To investigate the cause(s) of such variable tensile behavior, several specimens from Target 2, spanning the range of observed tensile behavior, were chosen for detailed microstructural examination using electron backscatter diffraction (EBSD) analysis. It was shown that the steel employed in the construction of the target contained an unexpected bimodal grain size distribution, containing very large out-of-specification grains surrounded by "necklaces" of grains of within-specification sizes. The large grains were frequently comparable to the width of the gauge section of the tensile specimen. The propensity to form martensite during deformation was shown to be accelerated by radiation but also to be very sensitive to the relative orientation of the grains with respect to the tensile axis. Specimens having large grains in the gauge that were most favorably oriented for production of martensite strongly exhibited the traveling deformation wave phenomenon, while those specimens with less favorably oriented grains had lesser or no degree of the wave effect, thereby accounting for the observed data scatter.

  1. Oxidation and hydrolysis kinetic studies on UN

    NASA Astrophysics Data System (ADS)

    Rao, G. A. Rama; Mukerjee, S. K.; Vaidya, V. N.; Venugopal, V.; Sood, D. D.

    1991-11-01

    The reaction of oxygen and water vapour with UN microspheres containing 0.78 and 10.9 mol% UO 2 as impurity was studied under non-isothermal heating conditions in a thermobalance under different partial pressures of oxygen, a fixed pressure of water vapour in argon, and in air. Uranium mononitride was ultimately converted to U 3O 8, with the formation of UO 2 and U 2N 3 as intermediates. The end product of pyrohydrolysis was UO 2. The kinetic parameters were evaluated and the mechanism of the reaction was suggested. Different kinetic models were used to explain the oxidation behaviour of UN.

  2. Piqures massives par un essaim d'abeilles chez un enfant

    PubMed Central

    Berdai, Mohamed Adnane; Labib, Smael; El Balbal, Monia; Harandou, Mustapha

    2011-01-01

    Les piqûres multiples d'abeilles sont responsables d'envenimation sévère. Nous rapportons un cas d'une attaque massive par un essaim d'abeilles chez un enfant de sept ans. Sa gravité est liée à la localisation céphalique et au nombre important des piqûres qui était d'environ 270. Ses complications étaient l'insuffisance rénale, l'anémie et une conjonctivite. La prise en charge était symptomatique avec bonne évolution clinique et biologique. PMID:22187598

  3. Create Your Own "Un-Conference"

    ERIC Educational Resources Information Center

    Demski, Jennifer

    2012-01-01

    EdCamp is a grassroots movement of do-it-yourself professional development "un-conferences" that originated in Philadelphia in November 2010. In just a little over a year and a half the phenomenon has gained serious momentum across the country and now around the globe. This teacher-driven, bottom-up approach to professional development has…

  4. Un asteroide proveniente de la Luna

    NASA Astrophysics Data System (ADS)

    Tancredi, G.

    El descubrimiento de un débil objeto en movimiento por el telescopio Spacewatch (un instrumento dedicado a la búsqueda de Asteroides Cercanos a la Tierra) en 1991, ha generado una gran controversia en la comunidad planetaria. El objeto, denominado 1991 VG, tiene elementos orbitales llamativamente similares a los de la Tierra, lo que ha llevado a B. G. Marsden a aventurar:``El objeto podría ser una nave espacial en retorno (IAUC 5387)". Luego de analizar las características dinámicas de 1991 VG y las diferentes hipótesis sobre su origen, favorecemos la alternativa de que el objeto es un gran fragmento de material eyectado de la Luna durante un reciente impacto (en las últimas decenas de miles de años). El hallazgo en 1983 en la Antártida de meteoritos con composición tipo lunar, confirma la posibilidad de que material de la superficie del satélite puede ser eyectado a velocidades superiores a la de escape del sistema Tierra-Luna y alcance órbitas heliocéntricas. Los elementos orbitales de 1991 VG corresponden a los valores alcanzados por partículas que apenas escapan de la gravedad lunar y entran en órbitas heliocéntricas a través del punto Lagrangiano exterior del sistema Tierra-Sol.

  5. Teaching Information Literacy through "Un-Research"

    ERIC Educational Resources Information Center

    Hosier, Allison

    2015-01-01

    Students who write essays on research topics in which no outside sources are cited and where accuracy is treated as negotiable should generally not expect to receive good grades, especially in an information literacy course. However, asking students to do just this was the first step in the "un-research project," a twist on the familiar…

  6. Syndrome de Chilaiditi chez un nouveau-né, à propos d'un cas

    PubMed Central

    Cedrick, Sangwa Milindi; Maruis, Kitembo Feruzi; Mireille, Kakinga Zabibu; Nelly, Mukonda Sompo; Patience, Muhau Pfutila; Shem, Mapatano; Chamy, Cham Lubamba; Josephine, Monga Kalenga

    2014-01-01

    L'interposition du colon ou du grêle dans l'espace interhepatodiagramatique est une affection rare. Souvent asymptomatique et de découverte fortuite à la radiographie de l'abdomen, elle est plus rencontrée chez l'adulte de sexe masculin. Dans cet article, les auteurs présentent un cas exceptionnel d'un nouveau- né de sexe féminin porteur de cette anomalie. PMID:25848454

  7. 49 CFR 178.70 - Approval of UN pressure receptacles.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Approval of UN pressure receptacles. 178.70... PACKAGINGS Specifications for Cylinders § 178.70 Approval of UN pressure receptacles. (a) Initial design-type approval. The manufacturer of a UN pressure receptacle must obtain an initial design type approval from...

  8. 49 CFR 178.71 - Specifications for UN pressure receptacles.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Specifications for UN pressure receptacles. 178.71... PACKAGINGS Specifications for Cylinders § 178.71 Specifications for UN pressure receptacles. (a) General. Each UN pressure receptacle must meet the requirements of this section. Requirements for...

  9. 49 CFR 178.71 - Specifications for UN pressure receptacles.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Specifications for UN pressure receptacles. 178.71... FOR PACKAGINGS Specifications for Cylinders § 178.71 Specifications for UN pressure receptacles. (a) General. Each UN pressure receptacle must meet the requirements of this section. Requirements for...

  10. Korean "-(n)un," Salience, and Information Structure

    ERIC Educational Resources Information Center

    Kim, Ilkyu

    2013-01-01

    A Korean particle "-(n)un" is widely known as a topic and/or contrast marker. Despite this seemingly well-established view on the meaning/function of "-(n)un," however, its exact nature is far from clearly understood. The main purpose of this dissertation is to shed light on the meaning of "-(n)un," by looking at it…

  11. Torsion chronique d'une rate baladeuse chez un adolescent: à propos d'un cas

    PubMed Central

    Dème, Hamidou; Akpo, Léra Géraud; Fall, Seynabou; Badji, Nfally; Ka, Ibrahima; Guèye, Mohamadou Lamine; Touré, Mouhamed Hamine; Niang, El Hadj

    2016-01-01

    La rate baladeuse ou errante est une anomalie rare, qui est le plus souvent décrite chez l'enfant. Ses complications parmi lesquelles figure la torsion de son pédicule sont fréquentes et peuvent engager le pronostic vital du patient. Nous rapportons un cas de torsion chronique du pédicule d'une rate baladeuse chez un patient de 17 ans, au long passé de douleurs épigastriques. Le tableau clinique était marqué par une masse épigastrique spontanément douloureuse, évoluant depuis 48 heures. L’échographie abdominale objectivait une rate ectopique hétérogène, hypertrophiée, en position épigastrique et un hématome sous capsulaire. Au doppler, on notait une torsion du pédicule splénique à deux tours de spires et un petit flux sur l'artère splénique. La tomodensitométrie abdominale avec injection de produit de contraste montrait un défaut de rehaussement parenchymateux d'une grosse rate ectopique épigastrique et un hématome sous capsulaire. Le diagnostic de torsion chronique du pédicule d'une rate baladeuse, compliquée de nécrose et d'hématome sous capsulaire était retenu. Il a été réalisé une splénectomie. Les suites opératoires étaient simples. Nous discutons l'apport de l’échographie et de la TDM dans le diagnostic de la torsion chronique du pédicule d'une rate baladeuse. PMID:27583079

  12. Soins Aux Brules Apres Un Accident Nucleaire

    PubMed Central

    Bargues, L.; Donat, N.; Jault, P.; Leclerc, T.

    2010-01-01

    Summary Les lésions radiques sont dues le plus souvent à des radio-isotopes utilisés dans l’industrie. L’explosion d’un réacteur nucléaire, les armes nucléaires ou une attaque terroriste constituent un risque d’afflux massif de victimes brûlées. Les radiations ionisantes occasionnent des brûlures thermiques, des syndromes d’irradiation aiguë avec pancytopénie et des signes cutanés retardés. Après une période de latence, des symptômes cutanés apparaissent et leur profondeur est proportionnelle à la dose reçue. Les protocoles habituels de réanimation des brûlés s’appliquent ici. Les soins aux irradiés nécessitent aussi une mesure de l’irradiation et une décontamination par des personnels entraînés. En cas de catastrophe nucléaire, la priorité est d’optimiser les structures existantes et de préserver les moyens pour les patients ayant la plus forte probabilité de survie. Après un accident nucléaire isolé, les difficultés dans les centres de brûlés sont l’évaluation de la profondeur et les techniques chirurgicales de couverture cutanée. La préparation des moyens médicaux et des centres de brûlés est nécessaire pour faire face à la prise en charge de ces brûlures différentes et complexes. PMID:21991218

  13. UN spearheads drive on violence against women.

    PubMed

    To commemorate International Women's Day, more than 1000 victims of violence against women, activists, and celebrities from five continents participated in a video conference. UN Secretary General Kofi Annan declared that violence against women may be the most shameful human rights violation, and the Executive Director of the UN Development Fund for Women called violence against women "the most unpunished crime." Women from around the world described the culturally-sanctioned abuse they suffer, including female genital mutilation, wife murders, and dowry murders. The conference learned that more than 60 million women are missing in Asia because they were subjected to infanticide or were bartered away by their families to a life of domestic servitude or prostitution. Violence against women can take many forms, including domestic abuse, rape as a war crime, traditional practices, dowry and honor killings, and trafficking. In addition, at least 20% of women worldwide have been physically or sexually assaulted. The morbidity and mortality women suffer from violence is equal to that which they suffer from cancer.

  14. UN assesses the success of ICPD.

    PubMed

    1999-01-01

    In 1999, the international community will begin its first 5-year review of progress made in implementing the 20-year Programme of Action (POA) of the 1994 International Conference on Population and Development (ICPD). The POA signals the revolutionary agreement of 180 nations that human development and the empowerment of women are vital to stabilizing world population and achieving sustainable development. Delegates to the February 1999 Hague Forum will make recommendations for review by the March meeting of the UN Commission on Population and Development, which will serve as a preparatory committee meeting for a special session of the UN General Assembly. This special session will decide the next steps to be taken to foster implementation of the POA and will issue a report in July. Credit for achieving consensus on the POA is given to the 1200 representatives of nongovernmental organization (NGO) in attendance and to those who prepared for the ICPD by insuring that the voices of grassroots organizations were heard. Participation of NGO representatives at the Hague Forum will be limited to 800 in official sessions, but a 2-day NGO Forum will precede the Hague Forum. In the US, an NGO Coalition in Support of the Cairo Consensus will use its task force network to improve assessment and implementation activities while lobbying for sustained leadership and funding from the US. The POA includes 243 proposed actions and specific goals for the year 2015.

  15. UNS N10629: A new Ni-28%Mo alloy

    SciTech Connect

    Agarwal, D.C. ); Heubner, U.; Kohler, M.; Herda, W. )

    1994-10-01

    Early published work about alloys in the nickel-molybdenum system (namely, alloys B [UNS N10001] and B-2 [UNS N10665]) is reviewed. Results of several recent studies to prevent thermomechanical cracking during fabrication of components and stress corrosion cracking during service for alloy B-2 are presented. Data for a new alloy, UNS N10629, which has better alloy composition control than alloy B-2, also are given.

  16. Statistique des photons d'un laser à 4 niveaux soumis à un pompage optique

    NASA Astrophysics Data System (ADS)

    Chusseau, L.; Arnaud, J.; Philippe, F.

    2002-06-01

    Les lasers conventionnels à 4 niveaux peuvent délivrer de la lumière de statistique sous-Poissonienne même lorsqu'ils sont soumis à un pompage optique. Nous retrouvons exactement ces prédictions de l'optique quantique en supposant simplement que les atomes ont des niveaux d'énergie quantifiés interagissant avec un champ électromagnétique classique, la source du bruit optique étant les sauts quantiques entre niveaux. Des formules analytiques sont obtenues pour les deux paramètres clefs de la statistique des photons du laser: le facteur de Fano et la densité spectrale des photons émis.

  17. Navigation d'un vehicule autonome autour d'un asteroide

    NASA Astrophysics Data System (ADS)

    Dionne, Karine

    Les missions d'exploration planetaire utilisent des vehicules spatiaux pour acquerir les donnees scientifiques qui font avancer notre connaissance du systeme solaire. Depuis les annees 90, ces missions ciblent non seulement les planetes, mais aussi les corps celestes de plus petite taille comme les asteroides. Ces astres representent un defi particulier du point de vue des systemes de navigation, car leur environnement dynamique est complexe. Une sonde spatiale doit reagir rapidement face aux perturbations gravitationnelles en presence, sans quoi sa securite pourrait etre compromise. Les delais de communication avec la Terre pouvant souvent atteindre plusieurs dizaines de minutes, il est necessaire de developper des logiciels permettant une plus grande autonomie d'operation pour ce type de mission. Ce memoire presente un systeme de navigation autonome qui determine la position et la vitesse d'un satellite en orbite autour d'un asteroide. Il s'agit d'un filtre de Kalman etendu adaptatif a trois degres de liberte. Le systeme propose se base sur l'imagerie optique pour detecter des " points de reperes " qui ont ete prealablement cartographies. Il peut s'agir de crateres, de rochers ou de n'importe quel trait physique discernable a la camera. Les travaux de recherche realises se concentrent sur les techniques d'estimation d'etat propres a la navigation autonome. Ainsi, on suppose l'existence d'un logiciel approprie qui realise les fonctions de traitement d'image. La principale contribution de recherche consiste en l'inclusion, a chaque cycle d'estimation, d'une mesure de distance afin d'ameliorer les performances de navigation. Un estimateur d'etat de type adaptatif est necessaire pour le traitement de ces mesures, car leur precision varie dans le temps en raison de l'erreur de pointage. Les contributions secondaires de recherche sont liees a l'analyse de l'observabilite du systeme ainsi qu'a une analyse de sensibilite pour six parametres principaux de conception. Les

  18. From Domination to Partnership: Meeting the UN Millennium Goals

    ERIC Educational Resources Information Center

    Eisler, Riane; Corral, Thais

    2005-01-01

    The UN Millennium goals envision a more just and sustainable future. This article explains why there is a need to shift from domination model to a partnership model in meeting the UN Millennium goals. The domination model is a configuration based on top-down rankings of control, while the partnership model is a configuration that can support a…

  19. Ab initio modelling of UN grain boundary interfaces

    NASA Astrophysics Data System (ADS)

    Kotomin, E. A.; Zhukovkii, Yu F.; Bocharov, D.; Gryaznov, D.

    2012-08-01

    The uranium mononitride (UN) is a material considered as a promising candidate for Generation-IV nuclear reactor fuels. Unfortunately, oxygen in air affects UN fuel performance and stability. Therefore, it is necessary to understand the mechanism of oxygen adsorption and further UN oxidation in the bulk and at surface. Recently, we performed a detailed study on oxygen interaction with UN surface using density functional theory (DFT) calculations. We were able to identify an atomistic mechanism of UN surface oxidation consisting of several important steps, starting with the oxygen molecule dissociation and finishing with oxygen atom incorporation into vacancies on the surface. However, in reality most of processes occur at the interfaces and on UN grain boundaries. In this study, we present the results of first DFT calculations on O behaviour inside UN grain boundaries performed using GGA exchange-correlation functional PW91 as implemented into the VASP computer code. We consider a simple interface (310)[001](36.8°) tilt grain boundary. The N vacancy formation energies and energies of O incorporation into pre-existing vacancies in the grain boundaries as well as O solution energies were compared with those obtained for the UN (001) and (110) surfaces

  20. UN Peacekeepers: Soldiers with a Difference. Headline Series No. 292.

    ERIC Educational Resources Information Center

    Norton, Augustus Richard; Weiss, Thomas George

    United Nations (UN) peacekeepers, symbolic neutral military units whose presence has made a difference in areas as diverse as Afghanistan, Central America, and Namibia, are in a unique position to affect the course of international peace. With recent UN successes negotiating resolutions in Afghanistan and the Iran-Iraq war, and with radically…

  1. Realisation d'un detecteur de radioactivite pour un systeme microfluidique

    NASA Astrophysics Data System (ADS)

    Girard Baril, Frederique

    Pour etablir le comportement pharmacocinetique de nouveaux radiotraceurs en imagerie moleculaire, il est necessaire d'approfondir l'analyse realisee a partir d'une image par l'ajout d'une mesure dynamique de la radioactivite dans le sang. L'Universite de Sherbrooke developpe presentement une plateforme microfluidique d'echantillonnage et d'analyse permettant la mesure de la radioactivite du plasma en temps reel. L'objectif du present projet de maitrise etait de realiser le composant optoelectronique responsable de la detection des positrons et de l'integrer a la puce microfluidique. L'option retenue a ete l'utilisation de photodiodes PIN en silicium. Un procede de fabrication, ainsi qu'une serie de photomasques ont ete developpes afin de produire une premiere iteration de prototypes. Les detecteurs ont ete concus de maniere a optimiser leur sensibilite en fonction du type de rayonnement a detecter. En effet, la region de detection doit etre suffisamment epaisse et sensible pour absorber le maximum de particules energetiques. Egalement, il est essentiel de minimiser le courant de fuite en noirceur afin d'obtenir un photocourant directement proportionnel a l'energie des radiations incidentes. Les caracteristiques electriques obtenues avec les premiers detecteurs ont ete demontrees proches des performances de detecteurs commerciaux similaires. De plus, il a ete possible d'integrer un canal microfluidique au substrat contenant les photodiodes et d'en realiser l'encapsulation sans alterer les performances electriques initiales des detecteurs. Une courbe de l'activite radioactive du 18F a ete mesuree, celle-ci se comparant a l'activite theorique associee a ce radioisotope communement utilise en TEP. Enfin, un spectre en energie des emissions radiatives du 18F a ete mesure et compare aux performances de systemes utilisant des photodiodes commerciales. Il a ete demontre que le prototype offrait un rapport signal sur bruit similaire aux systemes bases sur des photodiodes

  2. House battles over UN family planning funds.

    PubMed

    1997-05-01

    The House International Relations Subcommittee on Operations and Human Rights approved HR 1253 by voice vote on April 10, 1997. HR 1253 is a reauthorization of State Department programs for fiscal years 1998 and 1999. Republican anti-choice subcommittee chair Chris Smith inserted language which prohibits the State Department from funding the UNFPA, the UN family planning program. The restriction would only be lifted if President Clinton certifies that the UNFPA has ended all activities in China or that no government-coerced abortions have taken place in China during the previous 12 months. Since neither change is likely, the Smith provision would effectively bar the US from funding the UNFPA, even though the agency does not support abortion services. The State Department authorization was then taken up by the full House International Relations Committee as part of HR 1486, a bill which would reorganize foreign policy operations. By a 23-16 vote on May 6, the committee approved an amendment which deleted the Smith provision and instead stipulated that US funds cannot be used for UNFPA programs in China. Pro-choice representative Tom Campbell sponsored the amendment which deleted the Smith provision. President Clinton's proposed budget for fiscal year 1998 also includes the Campbell provision. PMID:12292412

  3. Synthesis and sintering of UN-UO2 fuel composites

    NASA Astrophysics Data System (ADS)

    Jaques, Brian J.; Watkins, Jennifer; Croteau, Joseph R.; Alanko, Gordon A.; Tyburska-Püschel, Beata; Meyer, Mitch; Xu, Peng; Lahoda, Edward J.; Butt, Darryl P.

    2015-11-01

    The design and development of an economical, accident tolerant fuel (ATF) for use in the current light water reactor (LWR) fleet is highly desirable for the future of nuclear power. Uranium mononitride has been identified as an alternative fuel with higher uranium density and thermal conductivity when compared to the benchmark, UO2, which could also provide significant economic benefits. However, UN by itself reacts with water at reactor operating temperatures. In order to reduce its reactivity, the addition of UO2 to UN has been suggested. In order to avoid carbon impurities, UN was synthesized from elemental uranium using a hydride-dehydride-nitride thermal synthesis route prior to mixing with up to 10 wt% UO2 in a planetary ball mill. UN and UN - UO2 composite pellets were sintered in Ar - (0-1 at%) N2 to study the effects of nitrogen concentration on the evolved phases and microstructure. UN and UN-UO2 composite pellets were also sintered in Ar - 100 ppm N2 to assess the effects of temperature (1700-2000 °C) on the final grain morphology and phase concentration.

  4. Synthesis and sintering of UN-UO2 fuel composites

    DOE PAGES

    Jaques, Brian J.; Watkins, Jennifer; Croteau, Joseph R.; Alanko, Gordon A.; Tyburska-Puschel, Beata; Meyer, Mitch; Xu, Peng; Lahoda, Edward J.; Butt, Darryl P.

    2015-06-17

    In this study, the design and development of an economical, accident tolerant fuel (ATF) for use in the current light water reactor (LWR) fleet is highly desirable for the future of nuclear power. Uranium mononitride has been identified as an alternative fuel with higher uranium density and thermal conductivity when compared to the benchmark, UO2, which could also provide significant economic benefits. However, UN by itself reacts with water at reactor operating temperatures. In order to reduce its reactivity, the addition of UO2 to UN has been suggested. In order to avoid carbon impurities, UN was synthesized from elemental uraniummore » using a hydride-dehydride-nitride thermal synthesis route prior to mixing with up to 10 wt% UO2 in a planetary ball mill. UN and UN – UO2 composite pellets were sintered in Ar – (0–1 at%) N2 to study the effects of nitrogen concentration on the evolved phases and microstructure. UN and UN-UO2 composite pellets were also sintered in Ar – 100 ppm N2 to assess the effects of temperature (1700–2000 °C) on the final grain morphology and phase concentration.« less

  5. Corrosion coupon testing in natural waters: A case history dealing with reverse osmosis desalination of seawater

    SciTech Connect

    Kain, R.M.; Adamson, W.L.; Weber, B.

    1997-12-31

    This paper describes a series of corrosion tests performed to determine the general and localized corrosion behavior of two stainless alloys (UNS S31603 and UNS N08367) and 70/30 CuNi (UNS C71500) in three aqueous environments associated with advanced reverse osmosis (TO) desalination of natural seawater. In addition to seawater (the RO feed stock), the other environments included a 2nd-pass RO brine with lower chloride content and total dissolved solids than raw seawater, and an ultrapure 3rd-pass permeate. Two ASTM standards were reviewed for guidance in the design of the experiment. Since testing could be conducted in an operating prototype RO system, the test program followed the general procedures for an in-plant corrosion tests described by ASTM G4-95: Standard Guide for Conducting Corrosion Coupon Tests in Field Applications. This standard, along with G78-95: Standard Guide for Crevice Corrosion Testing of Iron-Base and Nickel-Base Alloys in Seawater and Other Chloride-Containing Environments, provided guidance in the selection of test specimens and mounting fixtures as well as crevice formers utilized. The G78-95 standard guide also provided considerations associated with the interpretation of the crevice corrosion test results.

  6. President Barack Obama at UN Climate Change Summit

    ScienceCinema

    Obama, Barack

    2016-07-12

    In his first address to the United Nations as Commander-in- Chief, President Obama addresses the pressing issue of climate change. The one-day UN summit brought together delegations from 90 nations. September 22, 2009 (Public Domain)

  7. President Barack Obama at UN Climate Change Summit

    SciTech Connect

    Obama, Barack

    2009-01-01

    In his first address to the United Nations as Commander-in- Chief, President Obama addresses the pressing issue of climate change. The one-day UN summit brought together delegations from 90 nations. September 22, 2009 (Public Domain)

  8. UFO (UnFold Operator) computer program abstract

    SciTech Connect

    Kissel, L.; Biggs, F.

    1982-11-01

    UFO (UnFold Operator) is an interactive user-oriented computer program designed to solve a wide range of problems commonly encountered in physical measurements. This document provides a summary of the capabilities of version 3A of UFO.

  9. WHO board backs new UN programme on HIV / AIDS.

    PubMed

    1994-01-01

    The World Health Assembly requested a feasibility study May 1993 to determine how United Nations (UN) organizations and the UN overall could most effectively help countries respond to the HIV/AIDS pandemic. After weighing three options for a joint UN program against HIV/AIDS, the Executive Board of the World Health Organization (WHO) decided to support the creation of one approach for a joint, cosponsored program on HIV/AIDS to boost global response. Main program objectives are to strengthen governments' capacity to coordinate and implement HIV/AIDS activities at country level, to provide global leadership in response to the pandemic, to advocate greater political commitment; to provide technical, strategic, and policy direction; and to ensure collaboration among UN, governmental, and nongovernmental organizations. The resolution was adopted by consensus January 21, 1994, at a meeting of WHO's 31-member Executive Board in Geneva. The proposal will now be put to the governing bodies of the other potential cosponsors; the program could begin operations by the end of 1995. UNICEF, UNDP, UNESCO, UNFPA, and the World Bank have all expressed their intent to participate fully in the program. It will consist of an unified interagency secretariat administered and located within WHO which will have overall responsibility for providing the UN system with strategic and policy guidance on HIV/AIDS. Coordinated fund-raising will be conducted at global and country levels. The program will offer technical and other support to national AIDS programs currently supplied to countries by the Global Program on AIDS, with each country having an HIV/AIDS committee established by the UN Resident Coordinator to coordinate UN activities on HIV/AIDS. It is hoped that this new approach will provide a comprehensive, coordinated, and more effective UN response to HIV/AIDS while making the best use of available national and international resources.

  10. Sarcome à cellules claires du rein : À propos d’un cas chez un jeune de 17 ans

    PubMed Central

    Mazdar, Adil; Sakel, Adil Ait; Essatara, Younes; Beddouche, Ali; Elsayegh, Hachem; Iken, Ali; Benslimane, Lounis; Nouini, Yassine

    2014-01-01

    Résumé Le sarcome à cellules claires du rein (SCCR) se voit très rarement chez les jeunes. Il est caractérisé par une évolution agressive marquée par un taux élevé de récidive et de mortalité. Nous rapportons le cas d’un SCCR chez un patient de 17 ans et nous discutons de son apport et de son intérêt médical en vue d’une bonne prise en charge thérapeutique. L’agressivité du SCCR et la prolifération de métastases surtout osseuses impliquent qu’il ne faut pas méconnaître ce diagnostic afin de mettre en place un traitement adapté. PMID:24940474

  11. Kyste hydatique du foie compliqué d'un accident vasculaire cérébral ischémique: à propos d'un cas

    PubMed Central

    Turki, Olfa; Bahloul, Mabrouk; Chtara, Kamilia; Regaieg, Kais; Haddar, Sondes; Bouaziz, Mounir

    2015-01-01

    Le kyste hydatique du foie (KHF) est une maladie assez répandue dans les pays nord-africains. La rupture post-traumatique ou spontanée du kyste compliquée d'un choc anaphylactique et d'un AVC ischémique a été exceptionnellement rapportée. Nous rapportons un cas d'un kyste hydatique du foie (KHF) fissuré et compliqué d'un choc anaphylactique et d'un AVC ischémique. PMID:26985273

  12. Arthrite à pneumocoque chez un adulte immunocompétent

    PubMed Central

    Chemsi, Hicham; Chadli, Maryama; Sekhsokh, Yassine

    2015-01-01

    Les infections à pneumocoques sont avant tout respiratoires, ORL et méningées. Les infections ostéoarticulaires à pneumocoque ont la particularité de survenir dans moins de 20% des cas chez l'adulte sain. Habituellement, un ou plusieurs facteurs favorisants sont retrouvés. Toutefois, nous rapportons lors de cette observation le cas d'une arthrite à Streptococcus pneumoniae chez un adulte immunocompétent sans facteurs prédisposant. Patient âgé de 66 ans, diabétique de type II, a été hospitalisé pour une décompensation acido-cétosique et une monoarthrite du genou droit. Ce patient était fébrile (39°C) et présentait un genou droit inflammatoire en flexion avec rougeur et chaleur locale et un choc rotulien. Une ponction articulaire avec d'autres examens ont été réalisés pour confirmation d'une arthrite septique à pneumocoque. Le résultat de la ponction articulaire réalisée a montré un liquide jaune citron trouble avec 480 000 leucocytes/mm3 à prédominance polynucléaires neutrophiles. L'examen direct a montré des coccis à Gram positif en diplocoque, la culture a permis d'isoler un Streptococcus pneumoniae sensible à la pénicilline G. L’évolution clinique et biologique de l'arthrite du genou était favorable. Un déficit immunitaire, un asplénisme anatomique ou fonctionnel peuvent être en cause. L'alcoolisme est un facteur favorisant mais le mécanisme n'est pas clairement élucidé. La présence de matériel prothétique, peut favoriser une localisation septique. Ces facteurs de risque doivent être systématiquement recherchés, notamment en cas d'infection grave ou récidivante, une antibioprophylaxie ou une vaccination pouvant être proposées chez les sujets à haut risque. PMID:26327976

  13. 40 CFR Table I-8 to Subpart I of... - Default Emission Factors (1-UN2O,j) for N2O Utilization (UN2O,j)

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Default Emission Factors (1-UN2O,j) for N2O Utilization (UN2O,j) I Table I-8 to Subpart I of Part 98 Protection of Environment... Factors (1-UN2O,j) for N2O Utilization (UN2O,j) Process type factors N2O CVD 1-Ui 0.8 Other...

  14. 40 CFR Table I-8 to Subpart I of... - Default Emission Factors (1-UN2O j) for N2O Utilization (UN2O j)

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Default Emission Factors (1-UN2O j) for N2O Utilization (UN2O j) I Table I-8 to Subpart I of Part 98 Protection of Environment... Factors (1-UN 2 O j) for N2O Utilization (UN2 O j) Process type factors N2O CVD 1-Ui 0.8...

  15. Textilome abdominal, à propos d'un cas

    PubMed Central

    Erguibi, Driss; Hassan, Robleh; Ajbal, Mohamed; Kadiri, Bouchaib

    2015-01-01

    Le textilome, également appelé gossybipomas, est une complication postopératoire très rare. Il peut s'agir d'un corps étranger composé de compresse(s) ou champ(s) chirurgicaux oubliés au niveau d'un foyer opératoire. Ils sont plus souvent asymptomatiques, et difficile à diagnostiquer. En particulier, les cas chroniques ne présentent pas de signes cliniques et radiologiques spécifiques pour le diagnostic différentiel. L'anamnèse est donc indispensable pour le diagnostic vu que les signes cliniques ne sont pas concluants. Le cliché d'abdomen sans préparation est peu contributif, l’échographie est fiable. La tomodensitométrie permet un diagnostic topographique précis, mais ce n'est pas toujours le cas. Certaines équipes proposent des explorations par IRM. Nous rapportons un cas de textilome intra abdominal, chez une patiente de 31 ans opérée il y a 8 ans pour grossesse extra-utérine, chez qui la TDM abdomino-pelvienne a évoqué un kyste hydatique péritonéale sans localisation du foie. Traitée par extrait d'un petit champ de 25x15cm et adhérant au sigmoïde. Le but de ce travail est de mettre en évidence le problème de diagnostic de cette pathologie et l'importance de la laparotomie exploratrice. PMID:26523184

  16. La symphysite pubienne du post-partum: un diagnostic difficile

    PubMed Central

    Kehila, Mehdi; Majdoub, Manel; Zegha, Dorra; Khedher, Sonia Ben; Cheour, Elhem; Mahjoub, Sami

    2013-01-01

    La symphysite pubienne est une localisation rare de l'arthrite septique. Son association à la grossesse est exceptionnelle. Nous rapportons un cas de symphysite pubienne survenant dans les suites d'un accouchement par voie basse. Le diagnostic est difficile en post-partum. Il faut savoir l'évoquer devant toute douleur pubienne atypique dans sa présentation ou dans son évolution. Le diagnostic doit être posé de façon précoce car l'évolution peut se faire dans le cas contraire vers la chronicité. PMID:24498463

  17. Holoprosencephalie alobaire dans un contexte de syndrome polymalformatif: apport de l'imagerie, à propos d'un cas

    PubMed Central

    Amadou, Dia Aliou; Franck, D'Almeida; Mamadou, Mbodji; Mourtalla, Ka Mamadou

    2013-01-01

    L'holoprosencéphalie est une malformation cérébrale rare, d’étiologies multiples et souvent associée à des anomalies faciales évocatrices. Cette pathologie, résultant d'un défaut de développement précoce du prosencéphale, est de pronostic fœtal extrêmement réservé en particulier pour la forme alobaire. Nous rapportons à travers ce cas clinique, une holoproséncéphalie alobaire diagnostiquée à l'imagerie (ETF, tomodensitométrie) et relevée par un syndrome polymalformatif chez un nouveau-né de 03 mois. PMID:24171066

  18. Cryptococcose neuroméningée et tuberculose osseuse chez un immunocompétent: un cas

    PubMed Central

    Gbané-Koné, Mariam; Ouali, Boubacar; Mègne, Estelle; Diomandé, Mohamed; Coulibaly, Abidou Kawalé; Eti, Edmond; Kouakou, N'zué Marcel

    2015-01-01

    Les auteurs rapportent un cas de cryptococcose neuroméningée (CNM) chez un patient de 39 ans, non infecté par le VIH suivi pour une tuberculose de hanche. Le tableau clinique était celui d'une méningite subaiguë. Le diagnostic a été possible grâce à la mise en évidence de cryptocoques dans le LCR. L’évolution a été satisfaisante sous fluconazole. PMID:26090057

  19. Ab initio interionic potentials for UN by multiple lattice inversion

    NASA Astrophysics Data System (ADS)

    Chen, P. H.; Wang, X. L.; Lai, X. C.; Li, G.; Ao, B. Y.; Long, Y.

    2010-09-01

    Based on the Chen-Möbius lattice inversion and a series of pseudopotential total-energy curves, interionic pair potentials for UN were derived. By means of molecular dynamic (MD), we have examined this interionic potentials. Comparing with the experimental data, the thermal expansion coefficient and the compressibility were well reproduced by this potentials.

  20. [Sexual and reproductive rights during adolescence: UN-Brazil interactions].

    PubMed

    de Moraes, Silvia Piedade; Vitalle, Maria Sylvia de Souza

    2015-08-01

    The scope of this article is to describe the international documents of the UN and laws passed in Brazil from 1950 onwards focusing on sexual and reproductive rights during adolescence. It involved a descriptive study by consulting the official website of the UN organ entitled the Economic Commission for Latin America and the Caribbean and sites of the President of the Republic, Ministry of Health and Education and the Virtual Health Library. The documents were organized from 1950 to 2010 with an emphasis on sexual and reproductive rights and adolescence. Ten conferences were found within the scope of the UN: six conferences on Population and Development, two on Human Rights, one on the Rights of the Child and another on the Millennium Development Goals. Thirty-two documents were found in the field of national legislation (four decrees, thirteen federal laws, three technical norms, two ordinances, three resolutions, a technical note and six programs). The role of the UN and Brazil in consolidating the broad concept of sexual and reproductive rights has made significant progress, however greater achievements in the area of reproductive rights still prevail.

  1. Matiere sombre : Radioscopie d'un monde invisible

    NASA Astrophysics Data System (ADS)

    Jodra, S.; Harrois-Monin, F.; Bonnet-Bidaud, J. M.

    2002-05-01

    La face cachée de l'Univers est la cle de son evolution. Des resultats recents levent le voile sur l'energie sombre qui constitue la majeure partie du cote obscur du cosmos. Une bonne raison de faire le point sur l'autre composante invisible de l'Univers : la matiere "noire". Un portrait-robot circule deja.

  2. 49 CFR 178.70 - Approval of UN pressure receptacles.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... design-type approval. The manufacturer of a UN pressure receptacle must obtain an initial design type approval from the Associate Administrator. The initial design type approval must be of the pressure receptacle design as it is intended to be produced. The manufacturer must arrange for an IIA, approved by...

  3. Commande vectorielle d'un moteur asynchrone sans capteur

    NASA Astrophysics Data System (ADS)

    Ourth, T.

    1993-06-01

    A field-oriented control strategy for induction machines which does not use mechanical sensors is presented. The rotor flux is observed by a reduced-order Luenberger-type observer based on a model using a stator-fixed reference frame. An estimate of the rotation speed is derived from the flux vector, the measured stator currents and the field orientation angle. Simulations demonstrate that this control strategy performs well even in the presence of parameter variations up to ± 50% (resistances). Ce papier présente la commande par flux orienté d'une machine asynchrone sans capteur de vitesse ou de position. Le flux rotorique est évalué grâce à un observateur d'ordre réduit d'un type voisin de Luenberger travaillant dans un repère fixe statorique. L'estimation de la vitesse est obtenue à partir du module du flux rotorique, des courants statoriques mesurés et de l'angle d'orientation du flux rotorique. Cette étude basée sur des simulations démontre un comportement acceptable de la commande malgré la variation des paramètres comme les résistances de la machine.

  4. Blue sensors : technology and cooperative monitoring in UN peacekeeping.

    SciTech Connect

    Dorn, A. Walter Dr.

    2004-04-01

    For over a half-century, the soldiers and civilians deployed to conflict areas in UN peacekeeping operations have monitored ceasefires and peace agreements of many types with varying degrees of effectiveness. Though there has been a significant evolution of peacekeeping, especially in the 1990s, with many new monitoring functions, the UN has yet to incorporate monitoring technologies into its operations in a systematic fashion. Rather, the level of technology depends largely on the contributing nations and the individual field commanders. In most missions, sensor technology has not been used at all. So the UN has not been able to fully benefit from the sensor technology revolution that has seen effectiveness greatly amplified and costs plummet. This paper argues that monitoring technologies need not replace the human factor, which is essential for confidence building in conflict areas, but they can make peacekeepers more effective, more knowledgeable and safer. Airborne, ground and underground sensors can allow peacekeepers to do better monitoring over larger areas, in rugged terrain, at night (when most infractions occur) and in adverse weather conditions. Technology also allows new ways to share gathered information with the parties to create confidence and, hence, better pre-conditions for peace. In the future sensors should become 'tools of the trade' to help the UN keep the peace in war-torn areas.

  5. 49 CFR 178.71 - Specifications for UN pressure receptacles.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) Design and construction requirements for UN metal hydride storage systems. In addition to the general requirements of this section, metal hydride storage systems must conform to the following ISO standards, as... followed by the letters “BAR”. (7) The rated charging pressure of the metal hydride storage system in...

  6. Leiomyosarcome de la langue: à propos d'un cas

    PubMed Central

    El jahd, Lahcen; Barhmi, Ismail; Tazi, Nabil; Rouadi, Sami; Abada, Reda; Roubal, Mohammed; janah, Abdelaziz; Mahtar, Mohammed

    2015-01-01

    Le léiomyosarcome primitif de la langue est une tumeur rare qui se développe aux dépens des fibres musculaires lisses. Le diagnostic est souvent difficile, fondé sur des caractéristiques immuno-histologiques particulières. L'objectif de ce travail est de décrire le profil épidémiologique, clinique, thérapeutique et évolutif du léiomyosarcome à travers un cas et une revue de la littérature. Nous rapportons le cas d'un homme âgé de 26 ans, sans antécédents pathologique particuliers, consultant pour une tuméfaction de la langue mobile évoluant depuis 2 ans. Une biopsie de la masse a été réalisée. L’étude anatomopathologique et immunohistochimique a confirmé le diagnostic d'un léiomyosarcome de la langue. L'IRM de la langue a objectivé un processus lesionnel intéressant la portion mobile et antérieur de la langue. Une exérèse de la masse a été réalisée. L'examen histologique a montré la présence d'un large néoplasme de 6 cm compatible à un léiomyosarcome peu différencié de la langue, de garde II selon la Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC). Une radiothérapie externe sur la cavité buccale avec une dose de 65 Gy a été réalisée. Le patient a présenté 2 mois après la fin du traitement une adénopathie latéro-cervicale haute gauche (territoire II), il a bénéficié d'un curage ganglionnaire fonctionnel intéressant les territoires I, II et III puis réadressé en radiothérapie. Le léiomyosarcome de la langue est très rare surtout chez le sujet jeune. La chirurgie et la radiothérapie sont les armes thérapeutiques majeures. Le pronostic est très mauvais, Les facteurs les plus importants sont les marges d'exérèse et le grade. PMID:26600908

  7. Le lymphome primitif de la vessie: un cas clinique

    PubMed Central

    Statoua, Mouad; Mokrim, Maha; El Ghanmi, Jihad; Karmouni, Tariq; El Khadir, Khalid; Koutani, Abdellatif; Attya, Ahmed Iben; Errihani, Hassan

    2014-01-01

    Les tumeurs de vessie constituent les tumeurs les plus fréquentes de l'appareil uro-génital chez l'homme, le type histologique est dominé par le carcinome urothéliale, la localisation primitive du lymphome malin est extrêmement rare et constitue souvent une surprise diagnostique quand elle est retrouvée. Nous rapportons à travers cette observation le cas d'un patient pris en charge au sein de notre formation qui a bénéficié, suite a un bilan d'hématurie objectivant une formation bourgeonnante intra vésicale a l’échographie abdominale, d'une résection transurétrale de la vessie d'un polype géant dont les résultats anapathologies sont revenus en faveur d'un lymphome primitif de la vessie, le patient a bénéficié d'une chimiothérapie adjuvante a base de RCHOP, les suites étaient simples et une surveillance cystoscopique et scannographique n'a pas objectivé de récidive avec un recul de 18 mois. Le lymphome primitif de la vessie est une entité rare, sa chimio sensibilité fait de ce type de tumeur une maladie curable, le diagnostic est histologique et vu la rareté de l'affection aucun consensus n'est standardisé. PMID:25419286

  8. Conduite à tenir devant un utérus didelphe associé à un hémivagin borgne

    PubMed Central

    Alaoui, Fatima Zohra Fdili; Bouguern, Hakima; Jayi, Sofia; Squalli, Nadia; Melhouf, Moulay Abdilah

    2012-01-01

    L'utérus didelphe avec hémivagin borgne est une malformation rare, souvent diagnostiquée juste après les premières règles. La survenue d'un hématocolpos associée à une hématométrie et parfois un hématosalpinx est responsable de douleurs pelviennes et d'une dysménorrhée de plus en plus invalidante. Le diagnostic est posé par l’échographie pelvienne et selon l'urgence par l'imagerie par résonnance magnétique; l'agénésie rénale ipsilatérale est constante dans ce type de malformation. Le traitement consiste en une résection large de la cloison vaginale permettant ainsi un drainage continu de l'hémi utérus rétentionnel associé à une cœlioscopie objectivant les répercussions tubaires et pelviennes. Nous rapportons un cas d'utérus didelphe avec hémivagin borgne diagnostiqué à l’âge de 23 ans, nous discuterons à travers ce cas les aspects cliniques, diagnostiques et thérapeutiques de cette malformation utérine. PMID:23346270

  9. The prospect of uranium nitride (UN) and mixed nitride fuel (UN-PuN) for pressurized water reactor

    NASA Astrophysics Data System (ADS)

    Syarifah, Ratna Dewi; Suud, Zaki

    2015-09-01

    Design study of small Pressurized Water Reactors (PWRs) core loaded with uranium nitride fuel (UN) and mixed nitride fuel (UN-PuN), Pa-231 as burnable poison, and Americium has been performed. Pa-231 known as actinide material, have large capture cross section and can be converted into fissile material that can be utilized to reduce excess reactivity. Americium is one of minor actinides with long half life. The objective of adding americium is to decrease nuclear spent fuel in the world. The neutronic analysis results show that mixed nitride fuel have k-inf greater than uranium nitride fuel. It is caused by the addition of Pu-239 in mixed nitride fuel. In fuel fraction analysis, for uranium nitride fuel, the optimum volume fractions are 45% fuel fraction, 10% cladding and 45% moderator. In case of UN-PuN fuel, the optimum volume fractions are 30% fuel fraction, 10% cladding and 60% coolant/ moderator. The addition of Pa-231 as burnable poison for UN fuel, enrichment U-235 5%, with Pa-231 1.6% has k-inf more than one and excess reactivity of 14.45%. And for mixed nitride fuel, the lowest value of reactivity swing is when enrichment (U-235+Pu) 8% with Pa-231 0.4%, the excess reactivity value 13,76%. The fuel pin analyze for the addition of Americium, the excess reactivity value is lower than before, because Americium absorb the neutron. For UN fuel, enrichment U-235 8%, Pa-231 1.6% and Am 0.5%, the excess reactivity is 4.86%. And for mixed nitride fuel, when enrichment (U-235+Pu) 13%, Pa-231 0.4% and Am 0.1%, the excess reactivity is 11.94%. For core configuration, it is better to use heterogeneous than homogeneous core configuration, because the radial power distribution is better.

  10. The prospect of uranium nitride (UN) and mixed nitride fuel (UN-PuN) for pressurized water reactor

    SciTech Connect

    Syarifah, Ratna Dewi Suud, Zaki

    2015-09-30

    Design study of small Pressurized Water Reactors (PWRs) core loaded with uranium nitride fuel (UN) and mixed nitride fuel (UN-PuN), Pa-231 as burnable poison, and Americium has been performed. Pa-231 known as actinide material, have large capture cross section and can be converted into fissile material that can be utilized to reduce excess reactivity. Americium is one of minor actinides with long half life. The objective of adding americium is to decrease nuclear spent fuel in the world. The neutronic analysis results show that mixed nitride fuel have k-inf greater than uranium nitride fuel. It is caused by the addition of Pu-239 in mixed nitride fuel. In fuel fraction analysis, for uranium nitride fuel, the optimum volume fractions are 45% fuel fraction, 10% cladding and 45% moderator. In case of UN-PuN fuel, the optimum volume fractions are 30% fuel fraction, 10% cladding and 60% coolant/ moderator. The addition of Pa-231 as burnable poison for UN fuel, enrichment U-235 5%, with Pa-231 1.6% has k-inf more than one and excess reactivity of 14.45%. And for mixed nitride fuel, the lowest value of reactivity swing is when enrichment (U-235+Pu) 8% with Pa-231 0.4%, the excess reactivity value 13,76%. The fuel pin analyze for the addition of Americium, the excess reactivity value is lower than before, because Americium absorb the neutron. For UN fuel, enrichment U-235 8%, Pa-231 1.6% and Am 0.5%, the excess reactivity is 4.86%. And for mixed nitride fuel, when enrichment (U-235+Pu) 13%, Pa-231 0.4% and Am 0.1%, the excess reactivity is 11.94%. For core configuration, it is better to use heterogeneous than homogeneous core configuration, because the radial power distribution is better.

  11. 900 F embrittlement of alloy UNS N06625

    SciTech Connect

    Neubert, V.W.M.; Doelling, R.

    1998-12-31

    Different impellers made of nickel base alloy UNS N06625 have failed after 5000 h and 15000 h in service at high temperatures ({approx_equal} 500 C, 932 F) in 1994. The impellers were used in petrochemical industries. The failures were induced by stress corrosion cracking and stress corrosion fatigue. Material of the impellers showed a high susceptibility to intergranular corrosion and stress corrosion attack. Formation of a newly, not yet identified, super lattice within the nickel matrix has been discovered by transmission electron microscopy. The formation of the super lattice was caused by the service conditions, temperature and time. Based on these findings, influence of ageing time at 500 C (932 F) on the mechanical properties and the corrosion resistance of UNS N06625 was investigated. The specimen investigated showed strong differences in mechanical properties and corrosion behavior in standard corrosion test solutions, as well as a strong ageing dependence.

  12. Schroeder promises bill based on U.N. conference.

    PubMed

    1994-09-01

    Rep. Patricia Schroeder vowed yesterday (Sep. 5, 1994) to introduce legislation to ensure that the program adopted at the UN's population conference is carried out in US government policy. Mrs. Schroeder, a Colorado Democrat, told a news conference that legislators meeting on the side of the UN conference were concerned that the Program of Action would not be translated into concrete steps to improve the lot of women. "We want to organize and stay organized after this document is done to be sure there is follow-through," Mrs. Schroeder says. Mrs. Schroeder said that the Caucus for Women's Issues in the US Congress, which she co-chairs, was working on legislative proposals for introduction before adjournment. Rep. Constance A. Morella, a Republican from Maryland, joined Mrs. Schroeder in the call for legislation. She said the world's lawmakers at the conference were looking "beyond Cairo" and that it was important to increase funding for programs to improve the status.

  13. Sobrevivendo a un tsunami: lecciones de Chile, Hawai y Japon

    USGS Publications Warehouse

    Compilado por Atwater, Brian F.; Cisternas V., Marco; Bourgeois, Joanne; Dudley, Walter C.; Hendley, James W.; Stauffer, Peter H.

    1999-01-01

    Este folleto contiene historias veridicas que ilustran como sobrevivir, y como no sobrevivir, a un tsunami. Esta publicacion esta dirigida a las personas que viven, trabajan o, simplemente, se divierten a lo largo de las costas que pueden ser afectadas por un tsunami. Tales costas rodean la mayor parte del Oceano Pacifico pero tambien incluyen algunas areas costeras de los Oceanos Atlantico e Indico. Aunque mucha gente llama a los tsunamis 'olas de marea', estos no estan relacionados a las mareas, sino son una serie de olas, o 'tren de olas', generalmente causadas por cambios en el nivel del fondo marino durante los terremotos. Los tsunamis tambien pueden ser generados por la erupcion de volcanes costeros, islas volconicas, deslizamientos submarinos e impactos de grandes meteoritos en el mar. Como sucedio en Sumatra en el 2004, los tsunamis pueden alcanzar alturas de 15 metros, no tan solo en la costa sino tambien kilometros tierra adentro. Los relatos presentados en este folleto fueron seleccionados de entrevistas realizadas a personas que sobrevivieron al tsunami del Oceano Pacifico de 1960. Muchas de estas personas, incluyendo a la enfermera de la foto, se enfrento a las olas generadas a poca distancia, en la costa chilena. En cambio, otros debieron hacer frente al tsunami muchas horas despues, en Hawai y Japon. La mayoria de las entrevistas fueron realizadas a fines de los anos ochenta y en los noventa. Las historias ofrecen una mezcla de lecciones de supervivencia a un tsunami. En algunos casos se presentan las acciones que confiablemente salvaron vidas: poner atencion a los avisos de la naturaleza, abandonar los bienes, dirigirse rapidamente a un sector alto y permanecer alli hasta que el tsunami realmente haya terminado. Otras historias describen como se encontro refugio al subir a construcciones y arboles o flotar sobre desechos, tacticas que tuvieron diferentes resultados y que pueden ser recomendadas solo como actos desesperados de personas atrapadas en

  14. Metastase axillaire d'un carcinome papillaire de la thyroïde: à propos d'un cas

    PubMed Central

    El Khiati, Rhizlane; Ouaissi, Laila; Rouadi, Sami; Abada, Redallah; Mahtar, Mohamed; Roubal, Mohamed; Janah, Abdellah; Essaadi, Mustapha; Kadiri, Fatmi

    2013-01-01

    Les métastases axillaires dans le cadre d'un cancer de la thyroïde sont extrêmement rares. Plusieurs hypothèses expliquent ce drainage. Nous rapportons le cas d'un patient de 78 ans ayant pour antécédents chirurgicaux une lobo-isthmectomie en 1987, puis une totalisation chirurgicale en 1997 non documentés, admis en septembre 2008 pour exploration d'une masse latéro-cervicale gauche. Le reste de l'examen clinique révèle la présence de multiples adénopathies axillaires bilatérales. La biopsie exérèse d'une adénopathie axillaire droite (côté controlatéral) retrouve une métastase ganglionnaire d'un carcinome papillaire de la thyroïde avec effraction capsulaire. La tomodensitométrie cervico-thoracique note la présence d'un processus tumoral latéro-cervical gauche, un lobe thyroïdien droit siège de multiples nodules hypodenses, des adénopathies cervicales et axillaires et des lésions suspectes au niveau du parenchyme pulmonaire. Une thyroïdectomie totale avec curage ganglionnaire cervical est décidée, complétée par une ablation des ganglions axillaires macroscopiquement atteints. Des cures d'iode radioactif (IRA-thérapie) sont indiquées. Bien qu'exceptionnelle, la présence de métastases axillaires d'un carcinome thyroïdien est de pronostic péjoratif. On se demande alors si ces patients ne nécessitent pas une prise en charge particulière. Une réflexion à une stratégie thérapeutique est donc nécessaire. PMID:24498461

  15. Conception d'un generateur miniaturise d'ondes mecaniques

    NASA Astrophysics Data System (ADS)

    Riel, Louise-Philippe

    De nos jours, les maladies cardiaques représentent la première cause de décès dans le monde. Parmi ces maladies, les occlusions coronariennes occupent un rôle important. Aussi, 10 à 15 % de la population souffre de calculs urinaires et ces pourcentages augmentent d'année en année dans les pays industrialisés. Considérant ces données et le fait que les outils médicaux actuels ne permettent pas de répondre à l'ensemble des besoins exigés par ces domaines, il existe une opportunité intéressante pour le développement d'appareils mieux adaptés. Le présent mémoire a pour but de démontrer le potentiel technologique d'un générateur miniaturisé d'ondes mécaniques comme futur dispositif médical dans les domaines de la lithotritie intracorporelle et de la cardiologie d'intervention. Le générateur proposé exploite les ondes acoustiques (profil de pression) pour briser les calculs urinaires ou traverser les occlusions coronariennes. Le concept présenté vise à être plus efficace, plus sécuritaire et moins dispendieux que les appareils actuels. Pour parvenir à générer le profil de, pression désiré à l'extrémité d'une longue et mince tige, un processus d'amplification exploitant la focalisation des ondes dans un solide et la dispersion dans un guide d'ondes est utilisé. Ce processus nécessite une étape préliminaire de calibration qui permet de caractériser les propriétés acoustiques des milieux de propagation (concentrateur et guide dispersif). Tirant profit du retournement temporel, il est ensuite possible de concentrer spatialement et de compresser temporellement le signal de calibration pour former le profil de pression désiré. Le gain combiné de ces méthodes permettent de respecter les requis fixés pour l'appareil. Le prototype fabriqué est composé d'une source acoustique convergente, d'un guide d'ondes dispersif ainsi que d'un réducteur de section. La source acoustique comprend sept transducteurs pi

  16. First principles modelling of oxygen impurities in UN nuclear fuels

    NASA Astrophysics Data System (ADS)

    Kotomin, E. A.; Mastrikov, Yu. A.

    2008-07-01

    We report results of first principles VASP supercell calculations of O impurity in UN fuels placed either at an interstitial tetrahedral position or as a substitution for a host N ion. In the latter case O perfectly fits into N site producing no lattice distortion. Such the O substitutional impurity only slightly affects the formation energies of U and N vacancies nearby. In both interstitial and substitutional positions O atom attracts the additional electron density and transforms into the negatively charged ion. Oxygen incorporation into pre-existing N vacancy is energetically more favourable than into the interstitial position. The O impurities produce an additional peak at the low energy side of N contribution to the DOS calculated for uranium mononitride which could be used for the O identification by means of the UPS spectroscopy. We compare also the DOS calculated for UN and hypothetical isostructural UO. Both O solution and incorporation energies are negative, indicating that O penetration into UN fuel is the energetically favourable. The migration energy of the interstitial O ion is estimated as 2.8 eV.

  17. Crash simulation of UNS electric vehicle under frontal front impact

    NASA Astrophysics Data System (ADS)

    Susilo, D. D.; Lukamana, N. I.; Budiana, E. P.; Tjahjana, D. D. D. P.

    2016-03-01

    Sebelas Maret University has been developing an Electric Vehicle namely SmarT-EV UNS. The main structure of the car are chasis and body. The chasis is made from steel and the body is made from fiberglass composite. To ensure the safety of the car, both static and dynamic tests were carried out to these structures, including their materials, like: tensile test, bending test, and impact test. Another test needed by this vehicle is crashworthiness test. To perform the test, it is needed complex equipments and it is quite expensive. Another way to obtain vehicle crashworthiness behaviour is by simulate it. The purpose of this study was to simulate the response of the Smart-EV UNS electric vehicle main structure when crashing rigid barrier from the front. The crash simulation was done in according to the NHTSA (National Highway Traffic Safety Administration) within the speed of the vehicle of 35 mph. The UNS Electric Vehicle was modelled using SolidWorks software, and the simulation process was done by finite element method using ANSYS software. The simulation result showed that the most internal impact energy was absorbed by chassis part. It absorbed 76.2% of impact energy, then the base absorbed 11.3 %, while the front body absorbed 2.5 %, and the rest was absorbed by fender, hood, and other parts.

  18. Un coronographe interférentiel achromatique coaxial

    NASA Astrophysics Data System (ADS)

    Gay, Jean; Fressin, François; Rivet, Jean-Pierre; Rabbia, Yves; Buisset, Christophe

    2005-12-01

    xml:lang="fr">RésuméDans le but de parvenir à l'imagerie à haute dynamique d'objets comme les exoplanètes, nous présentons ici un nouveau concept de coronographe stellaire interférentiel, le « CIAXE ». Il est dérivé du « CIA », le Coronographe Interférentiel Achromatique. Le CIAXE se distingue de son prédécesseur par une combinaison optique originale, simplifiée, très compacte et totalement coaxiale. En effet, à la différence du CIA classique qui est dérivé de l'interféromètre de Michelson, le CIAXE délivre son faisceau de sortie sur le même axe que le faisceau d'entrée, ce qui facilitera grandement son insertion au sein de l'instrumentation focale d'un télescope. Un tel dispositif pourrait constituer une avancée en matière d'instrumentation focale pour la recherche d'exoplanètes. Pour citer cet article : J. Gay et al., C. R. Physique 6 (2005).

  19. Syndrome de compression traumatique: à propos d'un cas

    PubMed Central

    Boukatta, Brahim; El Bouazzaoui, Abderrahim; Houari, Nawfal; Jiber, Hamid; Sbai, Hicham; Kanjaa, Nabil

    2014-01-01

    Le crush syndrome correspond à l'ensemble des manifestations systémiques secondaire à une destruction des fibres musculaires striées. Il survient le plus souvent dans le cadre d'accidents graves tels que les catastrophes, accidents de travail et accidents de la voie publique. Il est responsable d'une hypovolémie, état de choc, hyperkaliémie, hypocalcémie, acidose métabolique et d'insuffisance rénale aigue. Le succès du traitement dépend largement de la rapidité de la prise en charge. Les principaux objectifs thérapeutiques sont la correction de l'hypovolémie, traitement de l'hyperkaliémie, l'alcalinisation et la prévention de l'insuffisance rénale. L'utilisation de garrots compressifs doit être réservée au seul contrôle d'hémorragies importantes. Dans cet article, nous rapportons le cas d'un jeune patient de 20 ans ayant présenté un crush syndrome à la suite d'un accident de la voie publique. L’évolution était favorable, mais une amputation du membre écrasé était nécessaire. PMID:25848457

  20. 49 CFR 180.207 - Requirements for requalification of UN pressure receptacles.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... approval has been obtained in writing from the Associate Administrator. (b) Periodic requalification of UN...) Requalification interval. Each UN pressure receptacle that becomes due for periodic requalification must be requalified at the interval specified in the following table: Table 1—Requalification Intervals of UN...

  1. 49 CFR 180.207 - Requirements for requalification of UN pressure receptacles.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... approval has been obtained in writing from the Associate Administrator. (b) Periodic requalification of UN...) Requalification interval. Each UN pressure receptacle that becomes due for periodic requalification must be requalified at the interval specified in the following table: Table 1—Requalification Intervals of UN...

  2. Métastases pleuropulmonaires révélant un mélanome malin de la conjonctive chez un sujet jeune

    PubMed Central

    El Ouazzani, Hanane; Janah, Hicham; El Machichi, Sabah Alami; Achachi, Leila; Fihry, Mohamed Taoufiq El Fassy; El Ftouh, Mohamed

    2016-01-01

    Le mélanome de la conjonctive est une tumeur rare avec une incidence de 0,03 à 0,08 pour 100000 dans la population blanche. Le mélanome malin métastatique constitue environ 5% de toutes les tumeurs malignes secondaires du poumon. Nous rapportons un cas de métastase pleurale et pulmonaire d'un mélanome conjonctival de découverte fortuite chez un sujet jeune. PMID:27231507

  3. Disjonction symphysaire après un accouchement par voie basse dystocique: à propos d'un cas

    PubMed Central

    Laadioui, Meriem; Slimani, Wafae; Jayi, Sofia; Alaoui, Fatimazahra Fdili; Bouguern, Hakima; Chaara, Hikmat; Melhouf, Moulay Aabdelilah

    2014-01-01

    La disjonction symphysaire est une affection rare, qui se définie par un élargissement au niveau de l'articulation inter-symphysaire estimé supérieur à 10 mm. Cette affection nécessite une prise en charge spécialisée en cas de douleurs sévères et invalidantes. Nous rapportant le cas d'une patiente présentant des douleurs pelviennes intense avec impotence du MI gauche à J2 d'un accouchement dystocique, l'examen clinique a objectivé une douleur exquise à la palpation de la symphyse pubienne. Le diagnostic a été confirmé par une radiologie du bassin de face objectivant un élargissement de la symphyse pubienne de 15 mm, la prise en charge thérapeutique a consisté en une mise sous décharge et anti-coagulation préventive avec un traitement antalgique à base de paracétamol et AINS. L’évolution était favorable. A travers notre cas, nous insisterons sur les caractéristiques de cette pathologie notamment pronostic, ce qui permettra au praticien de comprendre l'intérêt du diagnostic et prise en charge précoce de cette entité qu'elle évoquer devant toute douleurs pelviennes survenant au cours de la grossesse ou en post partum. PMID:24932344

  4. Un syndrome confusionnel révélant un syndrome de Fahr avec hyperparathyroïdie

    PubMed Central

    Rharrabti, Souad; Darouich, Ilhame; Benbrahim, Mohamed; Belahsen, Fawzi; Rammouz, Ismail; Alouane, Rachid

    2013-01-01

    Le syndrome de Fahr est une entité anatomo-clinique rare, caractérisée par des calcifications intracérébrales bilatérales et symétriques, localisées dans les noyaux gris centraux, le plus souvent associées à des troubles du métabolisme phosphocalcique. L'hypoparathyroïdie, primitive ou postopératoire, est l'anomalie la plus classique. L'hyperparathyroïdie est exceptionnellement rapportée comme cause du syndrome de Fahr. Nous rapportons le cas d'une fille de 17 ans suivie depuis l’âge de 12 ans pour une épilepsie avec la notion d'un retard mental depuis l'enfance, qui a présenté un syndrome confusionnel révélant un syndrome de Fahr avec la particularité de l'existence d'une hyperparathyroïdie. PMID:23734268

  5. DFT calculations of point defects on UN(001) surface

    NASA Astrophysics Data System (ADS)

    Bocharov, D.; Gryaznov, D.; Zhukovskii, Yu. F.; Kotomin, E. A.

    2011-02-01

    The density functional theory is used in a study of point defects on both UN(001) surface and sub-surface layers. We compare the results for slabs of different thicknesses (both perfect and containing nitrogen or uranium vacancies) with a full geometry, electronic and spin density optimization. The electronic charge density re-distribution, density of states, magnetic moments of U atoms and local atomic displacements around defects are carefully analyzed. It is predicted that the vacancies are formed easier on the surface, whereas the property of sub-surface layer does not differ significantly from the central one in the slab.

  6. New models for hyperspectral anomaly detection and un-mixing

    NASA Astrophysics Data System (ADS)

    Bernhardt, M.; Heather, J. P.; Smith, M. I.

    2005-06-01

    It is now established that hyperspectral images of many natural backgrounds have statistics with fat-tails. In spite of this, many of the algorithms that are used to process them appeal to the multivariate Gaussian model. In this paper we consider biologically motivated generative models that might explain observed mixtures of vegetation in natural backgrounds. The degree to which these models match the observed fat-tailed distributions is investigated. Having shown how fat-tailed statistics arise naturally from the generative process, the models are put to work in new anomaly detection and un-mixing algorithms. The performance of these algorithms is compared with more traditional approaches.

  7. Tuberculose orbitaire: à propos d'un cas

    PubMed Central

    Khrifi, Zineb; Abdellaoui, Meriem; Alaoui, Abdellah; Benatiya, Idriss Andaloussi; Tahri, Hicham

    2014-01-01

    La tuberculose sévit à l’état endémique au Maroc, l'atteinte orbitaire est rare et peut se faire par voie hématogène ou par contigüité à partir d'un foyer de voisinage. Nous rapportons le cas d'une patiente de 42 ans qui présente une exophtalmie droite dont l'enquête étiologique révèle une tuberculose orbitaire. PMID:25018814

  8. Nombre de valeurs polynomiales qui divisent un entier

    NASA Astrophysics Data System (ADS)

    de La Bretèche, R.

    2001-09-01

    Soit P un polynôme à coefficients entiers de degré 2 et [Delta] son discriminant. La quantité [tau]P(n), définie par [tau]P(n) := card {P(m) > 0: P(m)[mid R:]n, m [set membership] [open face Z]}, compte le nombre de diviseurs d de n qui s'écrivent sous la forme d = P(m). Lorsque P(X) = X(X + 1), le cardinal [tau]X(X+1)(n) est égal au nombre de diviseurs consécutifs de n.

  9. Un hémothorax gauche révélant une dissection de l`aorte: à propos d'un cas

    PubMed Central

    Siddo, Mouhamadou Nazirou Doddo; Bodian, Malick; Diaby, Falikou; Pessinaba, Soulemane; Ndiaye, Mouhamadou Bamba; Diao, Maboury; Mbaye, Alassane; Sarr, Simon Antoine; Coly, Sarah Mouna; Kane, Adama; Sarr, Moustapha; Ba, Serigne Abdou

    2014-01-01

    Certaines dissections de l`aorte peuvent se compliquer d'hémothorax faisant, évoquer initialement, une pathologie pleuro-pulmomaire. Nous rapportons l'observation d'un patient âgé de 67 ans, hypertendu, atteint d`une dissection de l`aorte, présentant un tableau typique, clinique et radiologique d`un syndrome d`épanchement pleural gauche en dehors de tout contexte infectieux et traumatique. Le tableau d`un syndrome pleural gauche a conduit à la réalisation d`une ponction pleurale qui a ramené un liquide hémorragique. La tomodensitométrie thoracique a conclu à une dissection aortique type B de Stanford. La prise en charge chirurgicale est indiquée en cas de complication comme ce fut le cas de notre patient. PMID:25426193

  10. First-principles study of structural, elastic, electronic, vibrational and thermodynamic properties of UN

    NASA Astrophysics Data System (ADS)

    Mei, Zhi-Gang; Stan, Marius; Pichler, Benjamin

    2013-09-01

    The structural, elastic, electronic, phonon and thermodynamic properties of UN are studied by density functional theory (DFT) within local-density approximation (LDA) and generalized gradient approximation (GGA), and GGA + U. The GGA calculations of the ground state structural and elastic properties of UN show an overall better agreement with experimental data compared to LDA or GGA + U. The melting temperature of UN (Tm) is estimated from the calculated elastic constant, with GGA predicting Tm = 2944 ± 300 K, in excellent agreement with experimental data. The calculated phonon dispersions of UN agree well with the low temperature measurements. Furthermore, the thermodynamic properties of UN are studied using quasiharmonic approximation by including both lattice vibrational and thermal electronic contributions. The predicted thermodynamic properties, such as enthalpy, entropy, Gibbs energy, heat capacity and thermal expansion coefficient, agree well with experimental data. The derived thermodynamic functions of UN are useful to the thermodynamic modeling of phase stabilities in UN-based materials. This study shows that the thermal electronic energy and entropy due to U 5f electrons are important to describe the free energy of UN, due to the metallic character of UN. The calculated thermodynamic properties also suggest that the anharmonic effects are less important in UN even at high-temperature.

  11. Diagnostic utility of quantitative EEG in un-medicated schizophrenia.

    PubMed

    Kim, Jun Won; Lee, Young Sik; Han, Doug Hyun; Min, Kyung Joon; Lee, Jaewon; Lee, Kounseok

    2015-03-01

    The aim of the current study was to evaluate the quantitative electroencephalography (QEEG) characteristics of patients with un-medicated schizophrenia (SPR) and to investigate the diagnostic utility of QEEG in assessing such patients during resting conditions. The subjects included 90 patients with schizophrenia and 90 normal controls. Spectral analysis was performed on the absolute power of all of the electrodes across five frequency bands following artifact removal. We conducted a repeated-measures ANOVA to examine group differences within the five frequency bands across several brain regions and receiver operator characteristic (ROC) analyses to examine the discrimination ability of each frequency band. Compared with controls, patients with schizophrenia showed increased delta and theta activity and decreased alpha 2 activity, particularly in the frontocentral area. There were no significant differences in the alpha 1 and beta activity. The ROC analysis performed on the delta frequency band generated the best result, with an overall classification accuracy of 62.2%. The results of this study confirmed the characteristics of the QEEG power in un-medicated schizophrenia patients compared with normal controls. These findings suggest that a resting EEG test can be a supportive tool for evaluating patients with schizophrenia.

  12. Difusión de Arnold en un modelo simple

    NASA Astrophysics Data System (ADS)

    Cincotta, P. M.; Nuñez, J. A.; Miloni, O.

    Investigadores como Merritt, Valluri, Pfenniger o Contopoulos (por citar los más relevantes) consideran seriamente la hipótesis que la difusión de Arnold juega un rol importante en la evolución dinámica de los sistemas estelares y planetarios. Sin embargo no existe ninguna evidencia. El mayor problema para investigar fenómenos como éste es que uno debe estudiar numéricamente sistemas multidimensionales (más de dos grados de libertad) y visualizar de alguna manera el espacio de fases (más de cuatro dimensiones). Más complicado aún es el caso de difusión de Arnold, donde deben considerarse tiempos de movimiento extremadamente largos y tratar con parámetros exponencialmente pequeños. El propósito de este trabajo es estudiar, en un modelo simple 3D, la existencia o no de difusión de Arnold mediante experimentos numéricos y estimaciones analíticas. Siguiendo los trabajos de Cincotta (2000) y Cincotta, Nuñez y Simo (2000), aquí se pretende ``visualizar" la difusión y, a la vez, determinar la escala de tiempo en la que ésta se podría manifestar. Este trabajo es el escalón inicial para luego abordar este problema en modelos.

  13. Kyste vestigial retrorectal: a propos d'un cas

    PubMed Central

    Mohamed, Hedfi; Taieb, Jomni; Cherif, Abdelhedi; Karim, Sassi; Adnene, Chouchene

    2015-01-01

    Les tumeurs rétro rectales kystiques et solides sont très variées et rare chez l'adulte. Elles sont dominées par les chordomes qui sont des tumeurs à malignité locale essentiellement observées chez les sujets de sexe masculin, alors les tumeurs kystiques vestigiales, sont souvent bénignes et prédominante chez la femme. Ces kystes congénitaux sont souvent asymptomatiques. L'apparition de symptôme à type des douleurs ou des troubles neurologiques devrait faire suspecter une dégénérescence. Une éventuelle surinfection tumorale peut poser le problème de diagnostic différentiel avec un abcès fistuleux, de traitement différent. Nous rapportons une observation insolite d'une patiente âgée de 52 ans explorée pour une lésion kystique retro rectale kystique en rapport avec un kyste vestigial traité chirurgicalement par voie trans sacrée. On se propose à travers cette observation insolite d’étudier les aspects diagnostique, évolutif et thérapeutique de ces lésions rares. PMID:27047626

  14. Spectroscopie VUV sub-picoseconde : un détecteur haute cadence et un monochromateur pour impulsions femtosecondes

    NASA Astrophysics Data System (ADS)

    Martin, P.; Belsky, A.; Zinin, E.; Philippov, A.; Idir, M.; Moreno, T.; Darpentigny, G.; Salin, F.

    2003-06-01

    La très faible durée des impulsions harmoniques VUV est incompatible avec les systèmes dispersifs “classiques” existant comme les monochromateurs VUV utilisés actuellement, principalement auprès des sources de rayonnement synchrotron. Nous avons conçu un monochromateur VUV (domaine spectral: visible-30nm, 4-40eV) capable de fonctionner sans dispersion temporelle d'impulsions de quelques dizaines de fs. Son principe est basé sur l'utilisation de deux réseaux fonctionnant dans des ordres opposés en configuration optique de type Seya-Namioka, avec des optiques toriques pour la pré et post focalisation. Compte tenu des contraintes imposées le pouvoir de résolution attendu (environ 100) est suffisant pour des applications en spectroscopie VUV. Dans le cadre de cette thématique développée au CELIA et plus particulièrement en ce qui concerne l'aspect dynamique de la relaxation électronique, nous présentons ici également un détecteur de photons de grande sensibilité appelé “dissecteur” dont la résolution actuelle est d'environ 13ps mais qui sera prochainement portée à 1ps.

  15. Structural, electronic, mechanical, and thermodynamic properties of UN 2: Systematic density functional calculations

    NASA Astrophysics Data System (ADS)

    Lu, Yong; Wang, Bao-Tian; Li, Rong-Wu; Shi, Hong-Liang; Zhang, Ping

    2011-03-01

    We have performed a comparative study of UN 2 and β-U 2N 3using the generalized gradient approximation (GGA) and the GGA + U approaches based on the density functional theory (DFT). The lattice parameters obtained from the GGA + U calculations can be ameliorated appreciably, however, the density of states (DOS) is insensitive to Hubbard U for both compounds. Our Bader analysis shows that the effective charges increase with decreasing U:N ratio (from UN to UN 2). The f electrons in UN 2 and β-U 2N 3 seem less localized than that in UN phase. The effects of Hubbard U on mechanical properties is evident, while the phonon dispersion depends weakly on the changes of Hubbard U. Based on our phonon dispersion data, the lattice vibration energy, thermal expansion, and specific heat are obtained by utilizing the quasiharmonic approximation (QHA).

  16. UO2-UN composites with enhanced uranium density and thermal conductivity

    NASA Astrophysics Data System (ADS)

    Yang, Jae Ho; Kim, Dong-Joo; Kim, Keon Sik; Koo, Yang-Hyun

    2015-10-01

    A mixed ceramic composite composed of UO2-UN was studied to increase both the thermal conductivity and uranium density of the currently used UO2 pellet. UN powder was synthesized by hydriding and then nitriding spherical U metal powders. Disk-shaped mixed UO2-UN composites were fabricated by hot pressing UO2-UN powder mixtures within a temperature range of 1300 °C-1590 °C. A phase analysis was conducted using X-ray diffraction and a SEM analysis indicated that the sintered composite consists mainly of a mixture of UO2 and UN phases. Compared to pure UO2, the UO2-33vol% UN composite showed an increase in uranium density of 13% (10.91 g/cm3) and an increase in thermal conductivity of up to 100% (8.16 W/m k at 800 °C).

  17. Métastases musculaires squelettique asymptomatique d'un cancer bronchique non à petites cellules

    PubMed Central

    Raoufi, Mohammed; Oukabli, Mohamed; Biyi, Abdelhamid; Elouazzani, Hanane; Rhorfi, Ismail Abderrahman; Abid, Ahmed

    2015-01-01

    Le cancer bronchique reste parmi les cancers les plus agressifs malgré les avancées diagnostiques et thérapeutiques, les métastases à distance constituent l’élément majeur d'un mauvais pronostic. Nous rapportons une observation de métastases musculaires chez un patient porteur d'un cancer du poumon inopérable. La détection de cette métastase était grâce au TEP scan au 18 FDG. Ce bilan a conduit à un traitement par chimiothérapie systémique après biopsie exérèse de la localisation fessière. Les métastases musculaires squelettiques du cancer bronchique sont rares mais bien qu'indiquant un mauvais pronostic, elles sont accessibles à un traitement local efficace. PMID:26918076

  18. Ostéochondrome volumineux de l'omoplate: à propos d'un cas

    PubMed Central

    Karabila, Mohamed Amine; Otmani, Leila; Azouz, Mohamed; Mhamdi, Younes; Hmouri, Ismail; Kharmaz, Mohamed; Bardouni, Ahmed; Lahlou, Abdou; Mahfoud, Mustapha; Salehberrada, Mohamed

    2015-01-01

    Nous rapportons le cas d'un ostéochondrome de l'omoplate ayant un aspect radiologique et une localisation inhabituelle chez un jeune homme de 24 ans qui consulte pour une déformation de son épaule gauche avec une bosse postérieure refoulant son omoplate. Un bilan radiologique standard a montré une exostose pédiculée à la partie supérieure de l'omoplate. La tomodensitométrie était en faveur d'une exostose volumineuse. La résection chirurgicale de la tumeur et l'examen anatomo-pathologique ont permis de confirmer le diagnostic d'un ostéochondrome. Après un recul de dix mois, les résultats fonctionnels étaient très bons. PMID:26985278

  19. Atrophie cérébrale diffuse au cours d'un syndrome de Goldenhar: à propos d'un cas

    PubMed Central

    Asani, Yogolelo; Mulenga, Cilundika; Ngombe, Léon Kabamba; Mbuyi-Musansayi; Muenze, Kalenga; Borasisi, Chenge; Speeg-Schatz

    2014-01-01

    Les auteurs rapportent un cas d'un syndrome de Goldenhar non décris dans la littérature chez un nourrisson de 3 mois, de sexe féminin présentant une atrophie cérébrale diffuse. Cette observation permet de décrire cette malformation rare et d'attirer l'attention de l'opinion scientifique à mettre en marche des études poussées afin de comprendre la survenue de cette pathologie. PMID:25767659

  20. La trochantérite tuberculeuse, un diagnostic souvent difficile

    PubMed Central

    Mhammdi, Younes; Boufettal, Moncef; Kharmaz, Mohamed; Lahlou, Abdou; Mahfoud, Mustapha; EL Bardouni, Ahmed; Berrada, Mohamed Saleh

    2016-01-01

    La trochantérite tuberculeuse est une affection rare (<2% des tuberculoses ostéo-articulaires), même en pays à forte endémie, elle est caractérisée par une symptomatologie insidieuse rendant souvent son diagnostic tardif. Les auteurs rapportent une série de 9 cas, le diagnostic a été posé sur des études bactériologiques et histologiques après un bilan d'imagerie (échographie, IRM, TDM). Le traitement de cette affection est médical (antibiothérapie antituberculeuse), et la chirurgie ne trouve sa place qu'en cas de complications et permet d'améliorer l’évolution. PMID:27279938

  1. Un cosmologiste oublié: Jean Henri Lambert

    NASA Astrophysics Data System (ADS)

    Débarbat, Suzanne; Lévy, Jacques

    Si les travaux de Kepler ont eu une large influence sure les progrès réalisés en astronomie au cours du 17e siècle, le Siècle de lumières a vu apparaître de nouvelles conceptions. La court vie de J.H. lambert s'inscrit dans le 18e siècle. Il s'agit d'un nom bien connu dans différents domaines (photométrie, projections cartographiques, mathématiques appliquées, etc.); mais il n'est guàre mentionné en cosmologie, alors que Lambert y a fourni une contribution originale offrant quelques suprenantes anticipations...

  2. Aircraft Altitude Estimation Using Un-calibrated Onboard Cameras

    NASA Astrophysics Data System (ADS)

    Naidu, V. P. S.; Mukherjee, J.

    2012-10-01

    In the present study, implementation and study of aircraft altitude estimation using un-calibrated onboard camera is obtained. A camera model has been implemented to simulate the test data. From the results, it was observed that the rounding nature of pixel coordinates creates fluctuations around the true vanishing point (VP) angle and height computations. These fluctuations were smoothened using a Kalman filter based state estimator. The effects of camera tilt and focal length on VP angle and height computations were also studied. It is concluded that the camera should be perpendicular to the runway for there to be no effect of the focal length on the height computation. It is being planned to apply this algorithm for real time imaging data along with Integrated Enhanced Synthetic Vision (IESVS) on HANSA aircraft.

  3. OXIDATION BEHAVIOR OF WELDED AND BASE METAL UNS N06025

    SciTech Connect

    Pint, Bruce A; Paul, Larry D.

    2007-01-01

    The oxidation behavior of specimens containing tungsten inert gas welds of UNS N06025 (NiCrFeAlY) was investigated in air for up to 5,000h at 900 -1000 C and 1,000h at 1100 -1200 C. In general, the microstructure was very homogeneous in the weld with smaller carbides and the Al2O3 penetrations were similar or smaller compared to those formed in the base metal. Above 1000 C, significant spallation was observed and Al and Cr depletion in the metal was observed to a similar extent in the weld and base metal. The maximum internal oxidation depth of the base metal at 900 and 1100 C was lower than several other commercial Ni-base alloys.

  4. Cavitation Erosion of Sensitized UNS S31803 Duplex Stainless Steels

    NASA Astrophysics Data System (ADS)

    Mitelea, Ion; Micu, Lavinia Mădălina; Bordeaşu, Ilare; Crăciunescu, Corneliu Marius

    2016-05-01

    During processing or use, duplex steels can be subjected to heating at high temperatures that can affect their behavior. This work aims to correlate the influence of the sensitization treatment on the ultrasonic cavitation erosion behavior of a UNS S31803 (X2CrNiMoN22-5-3) duplex stainless steel. Duplex stainless steels, formed as a result of rapid cooling after solution annealing, are sensitized at temperatures of 475 and 850 °C, respectively, leading to hardening and embrittlement due to the spinodal decomposition of the ferrite and the precipitation of secondary phases. The ultrasonic cavitation erosion experiments showed that the sensitization at 850 °C reduced the mean depth of erosion by about 11% and the mean depth of erosion rate by 28%. By contrast, the sensitization at 475 °C deteriorates the cavitation erosion resistance, increasing the erosion parameters by up to 22%, compared to the solution annealed state.

  5. Lymphome primitif du sein: à propos d'un cas

    PubMed Central

    Njoumi, Noureddine; Najih, Mohamed; Haqqi, Laila; Atolou, Gilles; Bougtab, Abdessalm; Hachi, Hafid; Benjelloun, Samir

    2012-01-01

    Le lymphome primitif du sein est une entité histologique très rare du cancer du sein. Les aspects cliniques et radiologiques ne présentent pas de spécificités particulières. Le diagnostic est souvent retardé. Le traitement se base essentiellement sur la chimiothérapie. Le pronostic est globalement péjoratif. Nous rapportons un cas de lymphome malin non Hodgkinien primitif du sein chez une patiente de 38 ans. Parallèlement une revue de la littérature est entreprise évoquant les aspects épidémiologiques, cliniques, histologiques et thérapeutiques de ce néoplasme. PMID:22937198

  6. Mise au point d'un reacteur epitaxial CBE

    NASA Astrophysics Data System (ADS)

    Pelletier, Hubert

    Ce projet de maîtrise consiste à l'asservissement et la mise en marche d'un réacteur d'épi-taxie par jets chimiques au Laboratoire d'Épitaxie Avancée de l'Université de Sherbrooke. Le réacteur sert à la croissance dans l'ultravide de matériaux semi-conducteurs tels que l'arséniure de gallium (GaAs) et le phosphure d'indium-gallium (GaInP). La programmation LabVIEW et du matériel informatique de National Instruments sont utilisés pour asservir le réacteur. Le contrôle de la température de l'échantillon et de la pression de contrôle des réactifs de croissance dans le réacteur est assuré par des boucles de rétroaction. Ainsi, la température de l'échantillon est stabilisée à ±0, 4 °C, alors que les pressions de contrôle de gaz peuvent être modulées sur un ordre de grandeur en 2 à 4 secondes, et stabilisées à ±0, 002 Torr. Le système de pompage du réacteur a été amélioré suite à des mesures de vitesse de pompage d'une pompe cryogénique. Ces mesures révèlent une dégradation sur plus d'un ordre de grandeur de son pompage d'hydrogène avec l'opération à long terme. Le remplacement de la pompe cryogénique par une pompe turbo-moléculaire comme pompe principale a permis d'améliorer la fiabilité du système de pompage du système sous vide. D'autre part, la conductance du système d'acheminement de gaz et d'injection a été augmentée afin de réduire un effet mémoire des sources le système et faciliter la croissance de matériaux ternaires. Ainsi, des croissances de GaAs (100) sur substrat de même nature ont été effectuées et ont révélé un matériau de bonne qualité. Sa rugosité moyenne de 0,17 nm, mesurée par microscopie à force atomique, est très faible selon la littérature. De plus, une mobilité élevée des porteurs est obtenue à fort dopage au silicium, au tellure et au carbone, notamment une mobilité de 42 ± 9 cm2V -1s-1 des porteurs majoritaires '(trous) lors du dopage au

  7. Révélation inhabituelle d’un carcinome rénal par un abcès du rein

    PubMed Central

    Saadi, Ahmed; Chlif, Mohamed; Ayari, Yassine; Gargouri, Mourad Mohamed; Sellami, Ahmed; Ben Rhouma, Sami; Nouira, Yassine

    2015-01-01

    Résumé La suppuration d’un carcinome rénal nécrosé a été rapportée seulement trois fois dans la littérature et demeure une circonstance exceptionnelle de découverte de cancer du rein. Le tableau clinique et radiologique est trompeur, et c’est l’évolution défavorable malgré un traitement approprié qui doit évoquer le diagnostic de cancer rénal. Nous rapportons un nouveau cas de carcinome rénal révélé par un abcès du rein. PMID:26664511

  8. Plasmocytome cutané secondaire révélant un myélome multiple: à propos d'un cas

    PubMed Central

    Ngolet, Lydie Ocini; N'soundhat, Norbert Lamini; Ndounga, Eliane; Kocko, Innocent; Kidédé, Daphtone Chabel Nkouala; Ntsiba, Honoré

    2016-01-01

    Le plasmocytome cutané secondaire métastatique est une prolifération plasmocytaire multiple extramédullaire de localisation cutanée. Son diagnostic repose sur la mise en évidence d'une prolifération plasmocytaire maligne au niveau médullaire et cutané. Son apparition s'associe à un stade avancé du myélome et à un pronostic péjoratif. PMID:27642385

  9. Utilisation D'un Modulateur de Phase Optique pour Realiser L'asservissement de la Frequence D'un Laser a Semi-Conducteurs

    NASA Astrophysics Data System (ADS)

    Levesque, Marc

    Cet ouvrage porte sur l'utilisation d'un modulateur de phase optique dans une boucle permettant d'asservir la frequence d'un laser a semi-conducteurs a une reference de frequence optique, en l'occurrence une vapeur atomique de rubidium 87. Nous y etudions principalement les mecanismes de generation du signal d'erreur. Un montage experimental est d'abord presente et la caracterisation complete du modulateur de phase est effectuee. Nous analysons ensuite les proprietes statiques du signal d'erreur dans le cas ou le signal applique au modulateur est periodique. Nous discutons de l'influence de parametres tels que la frequence et l'indice de modulation et la presence d'un effet Fabry -Perot accompagnant la modulation de phase. Enfin, nous montrons aussi qu'il est possible d'obtenir un signal d'erreur lorsque le signal de modulation est une sequence binaire aleatoire plutot qu'un signal periodique. Cela permet entre autres d'utiliser le meme modulateur de phase pour les fins de transmission et d'asservissement.

  10. Monitoring and Evaluation during the UN Decade of Education for Sustainable Development

    ERIC Educational Resources Information Center

    Tilbury, Daniella

    2007-01-01

    Monitoring and evaluation has been identified as one of seven key strategies for advancing the UN Decade of Education for Sustainable Development (DESD). The UN International Implementation Scheme for the Decade has called for the development of relevant and suitable indicators at all levels. Choosing appropriate education for sustainable…

  11. Synthesis of phase-pure U2N3 microspheres and its decomposition into UN.

    PubMed

    Silva, Chinthaka M; Hunt, Rodney D; Snead, Lance L; Terrani, Kurt A

    2015-01-01

    Uranium mononitride (UN) is important as a nuclear fuel. Fabrication of UN in its microspherical form also has its own merits since the advent of the concept of accident-tolerant fuel, where UN is being considered as a potential fuel in the form of TRISO particles. However, not many processes have been well established to synthesize kernels of UN. Therefore, a process for synthesis of microspherical UN with a minimum amount of carbon is discussed herein. First, a series of single-phased microspheres of uranium sesquinitride (U2N3) were synthesized by nitridation of UO2+C microspheres at a few different temperatures. Resulting microspheres were of low-density U2N3 and decomposed into low-density UN. The variation of density of the synthesized sesquinitrides as a function of its chemical composition indicated the presence of extra (interstitial) nitrogen atoms corresponding to its hyperstoichiometry, which is normally indicated as α-U2N3. Average grain sizes of both U2N3 and UN varied in a range of 1-2.5 μm. These also had a considerably large amount of pore spacing, indicating the potential sinterability of UN toward its use as a nuclear fuel.

  12. Anévrysme ventriculaire gauche et communication interventriculaire compliquant un infarctus du myocarde

    PubMed Central

    Belkhadir, Mohammed; MoutakiAllah, Younes; Raissouni, Zainab; Abdou, Abdessamad; Bamous, Mehdi; Nya, Fouad; Atmani, Noureddine; Houssa, Mahdi Ait; El Bekkali, Youssef; Boulahya, Abdellatif

    2014-01-01

    L'association d'une communication interventriculaire post infarctus du myocarde et d'un anévrysme du ventricule gauche chez un même patient est extrêmement rare et survient habituellement durant la première semaine qui suit un infarctus du myocarde. Nous rapportons le cas insolite d'un patient âgé de 63 ans, admis pour choc cardiogénique en rapport avec une communication inter ventriculaire apicale et un anévrysme ventriculaire gauche causés par un infarctus du myocarde antérieur. La correction chirurgicale a consisté en une fermeture du défect septal par un patch en dacron via une ventriculotomie gauche associée à une anévrysectomie et un mono pontage coronaire. Cette observation illustre d'une part la rareté de l'association communication inter ventriculaire-anévrysme ventriculaire gauche post infarctus du myocarde, et d'autre part l'efficacité du traitement chirurgical qui reste la seule option salvatrice pour cette pathologie. PMID:25328617

  13. Tracking Our Progress: A Global Monitoring and Evaluation Framework for the UN DESD

    ERIC Educational Resources Information Center

    Tilbury, Daniella

    2009-01-01

    The sustainability agenda is a concern of several UN agencies that appreciate how well-being, social justice, human development and the health of our planet are inextricably linked. This remit underpinned the launch of the UN Decade in Education for Sustainable Development (DESD) in 2005. As the DESD reaches its mid-point, mechanisms for assessing…

  14. Synthesis of phase-pure U2N3 microspheres and its decomposition into UN

    DOE PAGES

    Silva, Chinthaka M.; Hunt, Rodney Dale; Snead, Lance Lewis; Terrani, Kurt A.

    2014-12-12

    Uranium mononitride (UN) is important as a nuclear fuel. Fabrication of UN in its microspherical form also has its own merits since the advent of the concept of accident-tolerant fuel, where UN is being considered as a potential fuel in the form of TRISO particles. But, not many processes have been well established to synthesize kernels of UN. Therefore, a process for synthesis of microspherical UN with a minimum amount of carbon is discussed herein. First, a series of single-phased microspheres of uranium sesquinitride (U2N3) were synthesized by nitridation of UO2+C microspheres at a few different temperatures. Resulting microspheres weremore » of low-density U2N3 and decomposed into low-density UN. The variation of density of the synthesized sesquinitrides as a function of its chemical composition indicated the presence of extra (interstitial) nitrogen atoms corresponding to its hyperstoichiometry, which is normally indicated as α-U2N3. Average grain sizes of both U2N3 and UN varied in a range of 1–2.5 μm. In addition, these had a considerably large amount of pore spacing, indicating the potential sinterability of UN toward its use as a nuclear fuel.« less

  15. Pyomyosite tuberculeuse primitive chez une patiente immunocompétente: à propos d'un cas

    PubMed Central

    Daghfous, Alifa; Bouzaidi, Khaled; Marhoul, Lamia Rezgui

    2014-01-01

    L'atteinte du muscle strié au cours de la tuberculose chez un sujet immunodéprimé ou à partir de l'extension d'un foyer ostéo-articulaire de voisinage est rare mais bien connue. Toutefois, l'atteinte primitive est exceptionnelle ainsi que celle chez un sujet immunocompétent. L'imagerie par résonnance magnétique (IRM) est d'un grand apport pour le diagnostic avec une excellente sensibilité. Nous rapportons un cas de pyomyosite tuberculeuse primitive du mollet chez une patiente non immunodéprimé tout en précisant l'apport de l'IRM. PMID:25821543

  16. TELEMEDICINA: UN DESAFÍO PARA AMÉRICA LATINA

    PubMed Central

    Litewka, Sergio

    2011-01-01

    La telemedicina es una tendencia creciente en la prestación de los servicios médicos. Aunque la eficacia de esta práctica no ha estado bien establecida, es probable que los países en desarrollo compartirán este nuevo paradigma con los desarrollados. Los defensores de la telemedicina en América Latina sostienen que será una herramienta útil para reducir las disparidades y mejorar la accesibilidad de atención de salud. Aunque América Latina quizá se convierta en un lugar para la investigación e investigación de estos procedimientos, no está claro cómo la telemedicina podría contribuir a mejorar la accesibilidad para las poblaciones desfavorecidas, o coexistir con sistemas de atención de salud públicos crónicamente enfermos. Telemedicine is a growing trend in the provision of medical services. Although the effectiveness of this practice has not been well established, it is likely that developing countries will share this new paradigm with developed ones. Supporters of telemedicine in Latin America maintain that it will be a useful tool for reducing disparities and improving health care accessibility. Although Latin America might become a place for research and investigation of these procedures, it is not clear how telemedicine could contribute to improving accessibility for disadvantaged populations, or coexist with chronically ill-funded public healthcare systems. PMID:21625326

  17. Un-Fermi Liquids: Unparticles in Strongly Correlated Electron Matter

    NASA Astrophysics Data System (ADS)

    Langley, Brandon; Phillips, Philip; Hutasoit, Jimmy

    2014-03-01

    Since any non-trivial infrared dynamics in strongly correlated electron matter must be controlled by a critical fixed point, we argue that the form of the single-particle propagator can be deduced simply by imposing scale invariance. As a consequence, the unparticle picture proposed by Georgi is the natural candidate to describe such dynamics. Unparticle stuff is scale-invariant matter with no particular mass. Scale invariance dictates that the propagator has an algebraic form which can admit zeros and hence is a candidate to explain the ubiquitous pseudogap state of the cuprates. The non-perturbative electronic state formed out of unparticles we refer to as an un-Fermi liquid. We show that the underlying action of the continuous mass formulation of unparticles can be recast as an action in anti de Sitter space which serves as the generating functional for the propagator. We find that this mapping fixes the scaling dimension of the unparticle to be dU = d / 2 +√{d2 + 4 } / 2 and ensures that the corresponding propagator has zeros with d the spacetime dimension of the unparticle field. This work was funded by NSF DMR-1104909, DMR-1005536 and DMR-0820404.

  18. Néphrocalcinose compliquant une miliaire tuberculeuse chez un nourrisson

    PubMed Central

    El Maghraoui, Jaouad; Souilmi, Fatima Zahrae; Hbibi, Mohamed; Houssaini, Tarik Sqalli; Hida, Mustapha

    2015-01-01

    La néphrocalcinose se définit par la présence anormale dans le parenchyme rénal de dépôts calciques pouvant résulter de différentes affections. Nous rapportons le cas d'un nourrisson de 7 mois chez qui nous avons diagnostiqué une hypercalcémie compliquée par une néphrocalcinose secondaire à une tuberculose miliaire aggravée par l'intoxication à la vitamine D améliorée sous hyperhydratation, furosémide et glucocorticoïdes. A travers ce travail, nous insistons sur l'intérêt de la recherche d'une hypercalcémie devant toute infection tuberculeuse, de la prise en charge rapide et adaptée sans oublié d'interrompre la supplémentation en vitamine D. PMID:26309458

  19. TELEMEDICINA: UN DESAFÍO PARA AMÉRICA LATINA.

    PubMed

    Litewka, Sergio

    2005-01-01

    La telemedicina es una tendencia creciente en la prestación de los servicios médicos. Aunque la eficacia de esta práctica no ha estado bien establecida, es probable que los países en desarrollo compartirán este nuevo paradigma con los desarrollados. Los defensores de la telemedicina en América Latina sostienen que será una herramienta útil para reducir las disparidades y mejorar la accesibilidad de atención de salud. Aunque América Latina quizá se convierta en un lugar para la investigación e investigación de estos procedimientos, no está claro cómo la telemedicina podría contribuir a mejorar la accesibilidad para las poblaciones desfavorecidas, o coexistir con sistemas de atención de salud públicos crónicamente enfermos.Telemedicine is a growing trend in the provision of medical services. Although the effectiveness of this practice has not been well established, it is likely that developing countries will share this new paradigm with developed ones. Supporters of telemedicine in Latin America maintain that it will be a useful tool for reducing disparities and improving health care accessibility. Although Latin America might become a place for research and investigation of these procedures, it is not clear how telemedicine could contribute to improving accessibility for disadvantaged populations, or coexist with chronically ill-funded public healthcare systems.

  20. Mesure et retroaction sur un qubit multi-niveaux en electrodynamique quantique en circuit non lineair

    NASA Astrophysics Data System (ADS)

    Boissonneault, Maxime

    L'electrodynamique quantique en circuit est une architecture prometteuse pour le calcul quantique ainsi que pour etudier l'optique quantique. Dans cette architecture, on couple un ou plusieurs qubits supraconducteurs jouant le role d'atomes a un ou plusieurs resonateurs jouant le role de cavites optiques. Dans cette these, j'etudie l'interaction entre un seul qubit supraconducteur et un seul resonateur, en permettant cependant au qubit d'avoir plus de deux niveaux et au resonateur d'avoir une non-linearite Kerr. Je m'interesse particulierement a la lecture de l'etat du qubit et a son amelioration, a la retroaction du processus de mesure sur le qubit de meme qu'a l'etude des proprietes quantiques du resonateur a l'aide du qubit. J'utilise pour ce faire un modele analytique reduit que je developpe a partir de la description complete du systeme en utilisant principalement des transfprmations unitaires et une elimination adiabatique. J'utilise aussi une librairie de calcul numerique maison permettant de simuler efficacement l'evolution du systeme complet. Je compare les predictions du modele analytique reduit et les resultats de simulations numeriques a des resultats experimentaux obtenus par l'equipe de quantronique du CEASaclay. Ces resultats sont ceux d'une spectroscopie d'un qubit supraconducteur couple a un resonateur non lineaire excite. Dans un regime de faible puissance de spectroscopie le modele reduit predit correctement la position et la largeur de la raie. La position de la raie subit les decalages de Lamb et de Stark, et sa largeur est dominee par un dephasage induit par le processus de mesure. Je montre que, pour les parametres typiques de l'electrodynamique quantique en circuit, un accord quantitatif requiert un modele en reponse non lineaire du champ intra-resonateur, tel que celui developpe. Dans un regime de forte puissance de spectroscopie, des bandes laterales apparaissent et sont causees par les fluctuations quantiques du champ electromagnetique

  1. 49 CFR 173.302b - Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... may the internal pressure at 65 °C (149 °F) exceed the test pressure. (c) Fluorine, compressed, UN 1045 and Oxygen difluoride, compressed, UN 2190. Fluorine, compressed and Oxygen difluoride,...

  2. 49 CFR 173.302b - Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... may the internal pressure at 65 °C (149 °F) exceed the test pressure. (c) Fluorine, compressed, UN 1045 and Oxygen diflouride, compressed, UN 2190. Fluorine, compressed and Oxygen difluoride,...

  3. 49 CFR 173.302b - Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... may the internal pressure at 65 °C (149 °F) exceed the test pressure. (c) Fluorine, compressed, UN 1045 and Oxygen difluoride, compressed, UN 2190. Fluorine, compressed and Oxygen difluoride,...

  4. 49 CFR 173.302b - Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... may the internal pressure at 65 °C (149 °F) exceed the test pressure. (c) Fluorine, compressed, UN 1045 and Oxygen diflouride, compressed, UN 2190. Fluorine, compressed and Oxygen difluoride,...

  5. 49 CFR 173.302b - Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... may the internal pressure at 65 °C (149 °F) exceed the test pressure. (c) Fluorine, compressed, UN 1045 and Oxygen difluoride, compressed, UN 2190. Fluorine, compressed and Oxygen difluoride,...

  6. Electronic structure of crystalline uranium nitrides UN, U2N3 and UN2: LCAO calculations with the basis set optimization

    NASA Astrophysics Data System (ADS)

    Evarestov, R. A.; Panin, A. I.; Bandura, A. V.; Losev, M. V.

    2008-06-01

    The results of LCAO DFT calculations of lattice parameters, cohesive energy and bulk modulus of the crystalline uranium nitrides UN, U2N3 and UN2 are presented and discussed. The LCAO computer codes Gaussian03 and Crystal06 are applied. The calculations are made with the uranium atom relativistic effective small core potential by Stuttgart-Cologne group (60 electrons in the core). The calculations include the U atom basis set optimization. Powell, Hooke-Jeeves, conjugated gradient and Box methods are implemented in the author's optimization package, being external to the codes for molecular and periodic calculations. The basis set optimization in LCAO calculations improves the agreement of the lattice parameter and bulk modulus of UN crystal with the experimental data, the change of the cohesive energy due to the optimization is small. The mixed metallic-covalent chemical bonding is found both in LCAO calculations of UN and U2N3 crystals; UN2 crystal has the semiconducting nature.

  7. Exophtalmie de l’œil gauche en faveur d'un carcinome adénoide kystique orbitaire: à propos d'un cas

    PubMed Central

    Bouzidi, Adil; Iferkhass, Said; El Abidine Hansali, Zine; Elmallaoui, Mohammed; Laktaoui, Abdelkader

    2015-01-01

    Le Cylindrome orbitaire (carcinome adénoide kystique) est une tumeur maligne d'agressivité locale et d’évolution lente. Sa localisation orbitaire aux dépens des glandes lacrymales est exceptionnelle. Nous rapportons le cas d'un patient de 51 ans consultant pour une exophtalmie gauche non axile irréductible, douloureuse; avec ptosis modéré et baisse d'acuité visuelle. Une biopsie de la tumeur par voie palpébrale supérieure a été faite, en faveur d'un un carcinome adénoïde kystique cribriforme de la glande lacrymale. Après trois mois d'un traitement conservateur chirurgical, une exentération totale a été effectuée suivie d'une radiothérapie complémentaire. Le patient a été revu tout les 3 mois en consultation durant la première année. Sur un recul de six ans, le patient ne présente pas de signe en faveur d'une récidive. PMID:26893802

  8. Synthesis and sintering of UN-UO2 fuel composites

    SciTech Connect

    Jaques, Brian J.; Watkins, Jennifer; Croteau, Joseph R.; Alanko, Gordon A.; Tyburska-Puschel, Beata; Meyer, Mitch; Xu, Peng; Lahoda, Edward J.; Butt, Darryl P.

    2015-06-17

    In this study, the design and development of an economical, accident tolerant fuel (ATF) for use in the current light water reactor (LWR) fleet is highly desirable for the future of nuclear power. Uranium mononitride has been identified as an alternative fuel with higher uranium density and thermal conductivity when compared to the benchmark, UO2, which could also provide significant economic benefits. However, UN by itself reacts with water at reactor operating temperatures. In order to reduce its reactivity, the addition of UO2 to UN has been suggested. In order to avoid carbon impurities, UN was synthesized from elemental uranium using a hydride-dehydride-nitride thermal synthesis route prior to mixing with up to 10 wt% UO2 in a planetary ball mill. UN and UN – UO2 composite pellets were sintered in Ar – (0–1 at%) N2 to study the effects of nitrogen concentration on the evolved phases and microstructure. UN and UN-UO2 composite pellets were also sintered in Ar – 100 ppm N2 to assess the effects of temperature (1700–2000 °C) on the final grain morphology and phase concentration.

  9. TELEMEDICINA: UN DESAFÍO PARA AMÉRICA LATINA.

    PubMed

    Litewka, Sergio

    2005-01-01

    La telemedicina es una tendencia creciente en la prestación de los servicios médicos. Aunque la eficacia de esta práctica no ha estado bien establecida, es probable que los países en desarrollo compartirán este nuevo paradigma con los desarrollados. Los defensores de la telemedicina en América Latina sostienen que será una herramienta útil para reducir las disparidades y mejorar la accesibilidad de atención de salud. Aunque América Latina quizá se convierta en un lugar para la investigación e investigación de estos procedimientos, no está claro cómo la telemedicina podría contribuir a mejorar la accesibilidad para las poblaciones desfavorecidas, o coexistir con sistemas de atención de salud públicos crónicamente enfermos.Telemedicine is a growing trend in the provision of medical services. Although the effectiveness of this practice has not been well established, it is likely that developing countries will share this new paradigm with developed ones. Supporters of telemedicine in Latin America maintain that it will be a useful tool for reducing disparities and improving health care accessibility. Although Latin America might become a place for research and investigation of these procedures, it is not clear how telemedicine could contribute to improving accessibility for disadvantaged populations, or coexist with chronically ill-funded public healthcare systems. PMID:21625326

  10. First principles calculations of oxygen adsorption on the UN(0 0 1) surface

    NASA Astrophysics Data System (ADS)

    Zhukovskii, Yu. F.; Bocharov, D.; Kotomin, E. A.; Evarestov, R. A.; Bandura, A. V.

    2009-01-01

    Fabrication, handling and disposal of nuclear fuel materials require comprehensive knowledge of their surface morphology and reactivity. Due to unavoidable contact with air components (even at low partial pressures), UN samples contain considerable amount of oxygen impurities affecting fuel properties. In this study we focus on reactivity of the energetically most stable (0 0 1) substrate of uranium nitride towards the atomic oxygen as one of initial stages for further UN oxidation. The basic properties of O atoms adsorbed on the UN(0 0 1) surface are simulated here combining the two first principles calculation methods based on the plane wave basis set and that of the localized orbitals.

  11. First Principles Study of High Pressure Phase Transitions in ThN and UN

    NASA Astrophysics Data System (ADS)

    Modak, P.; Verma, Ashok K.

    2011-07-01

    We have carried out high pressure structural investigations of UN and ThN using ab initio total energy calculations. We have predicted that UN undergoes a structural transition from NaCl to R-3m structure at around 10 GPa pressure whereas that for ThN is absent. However at higher pressure (at 63 GPa) ThN transformed to CsCl structure. Our detailed analysis showed that NaCl structure becomes mechanically unstable at high pressure for UN but remains metastable for ThN.

  12. Rhabdomyosarcome paratesticulaire (RMSP) multimétastatique : à propos d’un cas

    PubMed Central

    Bennani, Hassan; Ziouziou, Imad; El Ghanmi, Jihad; Karmouni, Tarik; El Khader, Khalid; Koutani, Abdellatif; Andaloussi, Ahmed Iben Attya

    2014-01-01

    Résumé Nous rapportons, dans le présent article, le cas clinique d’un RMSP découvert à un stade tardif chez un adolescent, dans le but de confirmer l’évolution fatale de cette pathologie au potentiel métastatique « affreux ». Nous discutons aussi les causes du retard diagnostique, l’implication du sous-type histologique comme facteur pronostique et la place de la chimiothérapie dans le traitement des formes évoluées de la maladie. PMID:25295143

  13. Un-collided-flux preconditioning for the first order transport equation

    SciTech Connect

    Rigley, M.; Koebbe, J.; Drumm, C.

    2013-07-01

    Two codes were tested for the first order neutron transport equation using finite element methods. The un-collided-flux solution is used as a preconditioner for each of these methods. These codes include a least squares finite element method and a discontinuous finite element method. The performance of each code is shown on problems in one and two dimensions. The un-collided-flux preconditioner shows good speedup on each of the given methods. The un-collided-flux preconditioner has been used on the second-order equation, and here we extend those results to the first order equation. (authors)

  14. Syndrome CHARGE avec tétralogie de Fallot: à propos d'un cas

    PubMed Central

    Wahid, Fouad Amal; Seghrouchni, Aniss; Hatim, Abdedaim Elghadbane; Atmani, Noureddine; Abdou, Abdessamad; Bouzerda, Abdelmajid; Mouram, Sahar; Drissi, Mohamed; Houssa, Mahdi Ait; Boulahya, Abdelatif

    2014-01-01

    Le syndrome CHARGE est caractérisé par un large polymorphisme clinique associant colobome, anomalies cardiaques, atrésie de choanes, retard staturo-pondéral et de développement, anomalies génitales, anomalies des oreilles ainsi que d'autres anomalies. Les auteurs rapportent le cas d'un syndrome CHARGE diagnostiqué lors du bilan d'une tétralogie de Fallot chez un nourrisson de 22 mois. Les différentes manifestations cliniques de ce syndrome sont rapportées ainsi que les critères diagnostiques. PMID:25883746

  15. Strangulation du colon sigmoïdien par un testicule ectopique géant

    PubMed Central

    Sanogo, Zimogo; Koita, Adama; Camara, Moussa; Soumaré, Lamine; Kamaté, Bakarou; Doumbia, Dieneba; Ouattara, Zanafon; Tembely, Ali; Yena, Sadio; Coulibaly, Youssouf; Sangaré, Djibril

    2012-01-01

    Les causes de volvulus du colon sigmoïde sont variées et parmi elles la strangulation est des plus fréquentes dans notre contexte d’exercice. Les lésions vues tard permettent très rarement un traitement sans résection. La survenue d’un volvulus du colon sigmoïde autour d’un pédicule de testicule géant ectopique est une première que nous rapportons dans cette étude de cas. PMID:22593796

  16. Arteria lusoria associée à un tronc bi carotidien: à propos d'un cas et revue de la littérature

    PubMed Central

    Khnaba, Safae; Menany, Meryem; Moukinebillah, Mouna; Amil, Touriya; Radouane, Bouchayb

    2015-01-01

    L'arteria lusoria ou artère sous Clavière droite retro-œsophagienne constitue la malformation de l'arc aortique la plus fréquente, elle peut être associée à d'autres anomalies congénitales du cœur et des gros vaisseaux, notamment le tronc bi carotidien qui constitue un tronc commun donnant naissance aux deux artères carotides primitives internes. Nous rapportons le cas d'une patiente chez qui on a diagnostiqué un adénocarcinome gastrique, le scanner thoraco-abdominopelvien réalisé dans le cadre de son bilan d'extension a permis la découverte fortuite d'une artère aberrante retro-œsophagienne associé à un tronc bi carotidien. PMID:27047617

  17. La gangrène ischémique de la verge chez un patient diabétique: à propos d'un cas

    PubMed Central

    El Moutawakkil, Tarik; Elmortaji, Khalid; Arsalane, Amine; Ellahik, Driss; Aboutaieb, Rachid; Rabii, Redouane; Meziane, Fethi

    2015-01-01

    La gangrène de la verge est une pathologie rare mais grave. Les étiologies sont diverses avec essentiellement le diabète. Nous rapportons le cas d'un patient de 58 ans, diabétique et tabagique chronique ayant présenté une nécrose de la verge et avait bénéficié d'une amputation totale après deux interventions chirurgicale. L’évolution a été marquée par l'installation d'un sepsis et décès du patient. PMID:26491517

  18. U.N. Tightens Safe Sex Guidelines for Visitors to Zika Zones

    MedlinePlus

    ... news/fullstory_160807.html U.N. Tightens Safe Sex Guidelines for Visitors to Zika Zones Male and ... travelers, with or without symptoms, should practice safe sex or abstinence for 6 months after return To ...

  19. Œdème vulvaire massif pendant la grossesse: à propos d'un cas

    PubMed Central

    El Hassani, Moulay Elmehdi; Kassidi, Farid; Benabdejlil, Youssef; Kouach, Jaouad; Moussaoui, Driss Rahali; Dehayni, Mohammed

    2014-01-01

    L’œdème vulvaire massif est rare pendant la grossesse, mais requiert une attention particulière car il peut se greffer de complications maternelles et fœtales. Il peut être associé à plusieurs pathologies spécifiques ou non spécifiques à la grossesse dont le diagnostic fait appel obligatoirement à un interrogatoire et un examen clinique minutieux, puis à un bilan biologique standard. Le traitement doit être étiologique chaque fois que possible à coté du traitement symptomatique. Cette situation peut nécessiter un accouchement par césarienne. En dehors du risque potentiel de nécrose tissulaire et du risque exceptionnel de décès maternel associé à l’œdème vulvaire massif du post-partum l’évolution est favorable sous traitement bien conduit. PMID:25922627

  20. Dacryoadenite tuberculeuse bilatérale: à propos d'un cas

    PubMed Central

    Rezzoug, Bekkay; Tzili, Nazih; Ali, Hassan; Elyamouni, Oubaida; El Khaoua, Mahfoud; Elorch, Hamza; El Hlimi, Redouane; El Hassan, Abdallah; Berraho, Amina

    2015-01-01

    La dacryoadénite tuberculeuse est une inflammation rare de la glande lacrymale causé par le bacille Mycobacterium tuberculosis. Elle pose un problème étiopathogénique et diagnostique. Nous rapportons dans cette observation le cas d'une dacryoadénite tuberculeuse bilatérale chez un jeune homme Marocain de 34 ans ayant présenté une tuberculose ganglionnaire et du cavum il y à 14 ans, ayant été confirmé par l'examen anatomopathologique. La tuberculose reste un diagnostic qui doit être toujours évoqué même dans les atteinte bilatérale surtout si il y a un antécédent personnel ou familiale positif de tuberculose. Le pronostic de cette affection est devenu favorable grâce au traitement antibacillaire précoce. PMID:26015846

  1. Une angiocholite secondaire à un thrombus tumoral d'une tumeur neuroendocrine primitive du foie

    PubMed Central

    Baba, Hicham; Allaoui, Mohamed; Elfahssi, Mohammed; Bounaim, Ahmed; Ali, Abdelmounaim Ait; Oukabli, Mohamed; Sair, Khalid; Zentar, Aziz

    2015-01-01

    Nous rapportons le cas exceptionnel d'une patiente de 54 ans prise en charge pour une angiocholite due à un thrombus tumoral, d'une tumeur neuroendocrine primitive (TNE Ive) du foie, dans la voie biliaire principale. PMID:26966504

  2. Chemisorption of a molecular oxygen on the UN(0 0 1) surface: Ab initio calculations

    NASA Astrophysics Data System (ADS)

    Zhukovskii, Yu. F.; Bocharov, D.; Kotomin, E. A.

    2009-09-01

    The results of DFT GGA calculations on oxygen molecules adsorbed upon the (0 0 1) surface of uranium mononitride (UN) are presented and discussed. We demonstrate that O 2 molecules oriented parallel to the substrate can dissociate either (i) spontaneously when the molecular center lies above the surface hollow site or atop N ion, (ii) with the activation barrier when a molecule sits atop the surface U ion. This explains fast UN oxidation in air.

  3. Un cas de compression médullaire non traumatique atypique

    PubMed Central

    Narindra, Lova Hasina Rajaonarison Ny Ony; Ratovondrainy, Willy; Arolahy, Anja Holinoro Randriam; Rajaonarison, Pascal Jacques; Ahmad, Ahmad

    2015-01-01

    Les compressions médullaires non traumatiques de topographie dorsale sont rares. Nous rapportons un cas atypique de compression médullaire dorsale non traumatique chez un jeune homme de 19 ans présentant une paralysie flasque aréflexique avec amyotrophie importante des membres inférieurs, diagnostiquée au myéloscanner et confirmée en per opératoire. PMID:26161209

  4. Suicide after deployment in UN peacekeeping missions--a Danish pilot study.

    PubMed

    Hansen-Schwartz, J; Jessen, G; Andersen, K; Jørgensen, H O

    2002-01-01

    This pilot study looks at the frequency of suicide among Danish soldiers who took part in the UN mandated forces (UNMF) during the 1990's. In a contingent of nearly 4000 Danish UN soldiers four suicides were documented, two of whom committed suicide less than one month before deployment and two who committed suicide within a year after discharge from mission. Contributing factors, prevention strategies, and implications for future research are discussed. PMID:12500889

  5. Un kyste hydatique osseux: une localisation rare au niveau de l’os iliaque

    PubMed Central

    Nhamoucha, Yassine; Alaoui, Othmane; Doumbia, Aliou; Oukhoya, Mohammed; Abdellaoui, Hicham; Tazi, Mohammed; Chater, Lamyae; Atarraf, Karima; Arroud, Mounir; Afifi, Abderahman

    2016-01-01

    L'hydatidose est une affection parasitaire liée au développement chez l'homme de la forme larvaire d'un cestode, à savoir un tænia de très petite taille dénommé Echinococcus Granulosus. Cette anthropozoonose présente une diversité de formes anatomoradiologiques lié aux nombreux aspects topographiques et évolutifs des kystes. L'hydatidose osseuse est rare, elle ne représente que 0,9 à 2,5% de l'ensemble des localisations. Nous rapportons l'observation d'un enfant de 9 ans, qui a été admis chez nous pour une boiterie fébrile avec une masse au niveau de la fosse iliaque droite, révélant un kyste hydatique au dépend de l'os iliaque. Le bilan lésionnel avait objectivé un kyste hydatique de l'os iliaque avec extension aux parties molles adjacentes. Le traitement chirurgical conclu a un kyste surinfecté d'ou la réalisation d'une exérèse chirurgicale du kyste avec drainage. L'ostéopathie hydatique est infiltrante, diffuse, lente et progressive, ce qui rend le diagnostic tardif et qui compromet la qualité du traitement. PMID:27800081

  6. Le syndrome de Stewart-Treves compliquant un lymphœdème chronique idiopathique

    PubMed Central

    Safini, Fatima; Naim, Asmaa; Bouchbika, Zineb; Benchakroun, Nadia; Jouhadi, Hassan; Tawfiq, Nezha; Sahraoui, Souha; Benider, Abdellatif

    2014-01-01

    Le syndrome de Stewart-Treves (SST) est une entité rare, correspondant à un angiosarcome cutané compliquant un lymphoedème chronique. Il est de mauvais pronostic. Stewart et Treves ont rapportés en 1948, les premiers cas d'angiosarcome secondaire à un traitement du cancer du sein. Ce terme s'est généralisé pour regrouper l'ensemble des cas de lymphangiosarcome sur lymphoedème d'origine congénital héréditaire ou non héréditaire, post-traumatique ou post-infectieux. Le SST sur un lymphoedème idiopathique reste exceptionnel. Nous rapportons le cas rare d'une patiente présentant un lymphoedème chronique primitif idiopathique des quatre membres évoluant depuis l'adolescence et qui a développé un SST du membre supérieur droit. Elle a subi une amputation à mi- bras vu le caractère très évolué de la tumeur PMID:25883738

  7. Fracture négligée du capitellum chez un adulte: à propos d'un cas et revue de la literature

    PubMed Central

    Belmoubarik, Amine; Achargui, Anis; Azagui, Yassine; Bennouna, Driss

    2015-01-01

    Les auteurs rapportent un cas de fracture du capitellum négligée chez une femme de 36 ans ayant des limitations fonctionnelles. Après revue de la littérature, ils discutent le problème de la prise en charge thérapeutique et le pronostic de la lésion. PMID:26430481

  8. UN system machinery for coordinating follow-up to the World Food Summit.

    PubMed

    1997-12-01

    FAO [UN Food and Agriculture Organization] does not stand alone in implementing and monitoring the Summit Plan of Action. Commitments 7.2 and 7.3 give responsibility to the UN's Administrative Committee on Coordination (ACC) for coordinating interagency follow-up and to the Economic and Social Committee (ECOSOC) for receiving progress reports from FAO and other agencies. The UN General Assembly in December 1996 welcomed the outcome of the Summit and received FAO's first report on it at its 1997 session. The ACC has launched interagency follow-up by establishing the ACC Network on Rural Development and Food Security, as proposed jointly by FAO and the International Fund for Agricultural Development (IFAD). More than 16 UN agencies have joined and the UN Secretary-General has welcomed the intention to involve civil society and the emphasis placed on country-level action in the two-tiered network. All FAO country representatives and UN resident coordinators have been asked to help in setting up interagency thematic groups on rural development and food security at the country level. FAO has introduced a website for the network within SD Dimensions (http://www.fao.org/waicent/faoinfo/sustdev). ECOSOC has welcomed the ACC's decision to include follow-up to the World Food Summit within the context of the integrated follow-up process of all major UN conferences and summits. With these decisions, the machinery has been set in motion for early and sustained support from both interagency and intergovernmental bodies to national efforts to implement the Plan of Action. PMID:12321566

  9. Mass Spectrometry-Based Identification Of The Tumor Antigen UN1 as the Transmembrane CD43 Sialoglycoprotein*

    PubMed Central

    de Laurentiis, Annamaria; Gaspari, Marco; Palmieri, Camillo; Falcone, Cristina; Iaccino, Enrico; Fiume, Giuseppe; Massa, Ornella; Masullo, Mariorosario; Tuccillo, Franca Maria; Roveda, Laura; Prati, Ubaldo; Fierro, Olga; Cozzolino, Immacolata; Troncone, Giancarlo; Tassone, Pierfrancesco; Scala, Giuseppe; Quinto, Ileana

    2011-01-01

    The UN1 monoclonal antibody recognized the UN1 antigen as a heavily sialylated and O-glycosylated protein with the apparent molecular weight of 100–120 kDa; this antigen was peculiarly expressed in fetal tissues and several cancer tissues, including leukemic T cells, breast, and colon carcinomas. However, the lack of primary structure information has limited further investigation on the role of the UN1 antigen in neoplastic transformation. In this study, we have identified the UN1 antigen as CD43, a transmembrane sialoglycoprotein involved in cell adhesion, differentiation, and apoptosis. Indeed, mass spectrometry detected two tryptic peptides of the membrane-purified UN1 antigen that matched the amino acidic sequence of the CD43 intracellular domain. Immunological cross-reactivity, migration pattern in mono- and bi-dimensional electrophoresis, and CD43 gene-dependent expression proved the CD43 identity of the UN1 antigen. Moreover, the monosaccharide GalNAc-O-linked to the CD43 peptide core was identified as an essential component of the UN1 epitope by glycosidase digestion of specific glycan branches. UN1-type CD43 glycoforms were detected in colon, sigmoid colon, and breast carcinomas, whereas undetected in normal tissues from the same patients, confirming the cancer-association of the UN1 epitope. Our results highlight UN1 monoclonal antibody as a suitable tool for cancer immunophenotyping and analysis of CD43 glycosylation in tumorigenesis. PMID:21372249

  10. Modeling and Analysis of UN TRISO Fuel for LWR Application Using the PARFUME Code

    SciTech Connect

    Blaise Collin

    2014-08-01

    The Idaho National Laboraroty (INL) PARFUME (particle fuel model) code was used to assess the overall fuel performance of uranium nitride (UN) tristructural isotropic (TRISO) ceramic fuel under irradiation conditions typical of a Light Water Reactor (LWR). The dimensional changes of the fuel particle layers and kernel were calculated, including the formation of an internal gap. The survivability of the UN TRISO particle was estimated depending on the strain behavior of the constituent materials at high fast fluence and burn up. For nominal cases, internal gas pressure and representative thermal profiles across the kernel and layers were determined along with stress levels in the inner and outer pyrolytic carbon (IPyC/OPyC) and silicon carbide (SiC) layers. These parameters were then used to evaluate fuel particle failure probabilities. Results of the study show that the survivability of UN TRISO fuel under LWR irradiation conditions might only be guaranteed if the kernel and PyC swelling rates are limited at high fast fluence and burn up. These material properties have large uncertainties at the irradiation levels expected to be reached by UN TRISO fuel in LWRs. Therefore, a large experimental effort would be needed to establish material properties, including kernel and PyC swelling rates, under these conditions before definitive conclusions can be drawn on the behavior of UN TRISO fuel in LWRs.

  11. Relationship of the DOT`s regulations to the UN recommendations and international regulations

    SciTech Connect

    Saltzman, S.C.

    1994-12-31

    International, regional and national hazardous materials transportation regulations, including those of the US Department of Transportation, or DOT, are all being harmonized (i.e., made more uniform) by becoming fully based on the United Nations Recommendations on the Transport of Dangerous Goods. Effective last October, DOT`s regulations, Title 49 of the US Code of Federal Regulations, started requiring UN classification, marking, labeling, placarding and documentation. Full use of UN packaging in the US will be required by October 1996. Canada and Australia already adopted the UN Recommendations ahead of DOT; Mexico is in the process of doing so right now, and international air and ocean transport codes have required UN packaging for hazardous materials since 1990. European regional hazardous materials transportation regulations will also be harmonized with UN by 1995. Understanding how the international system is structured and the process by which it works will help to understand why and how the DOT regulations are changing, as well as the occasional differences between regulations. More importantly, this understanding allows one to anticipate changes, and either prepare for them, or try to head them off if there is the belief that they will be harmful to one`s industry.

  12. [Foraging intensity of ants in Solenopsis invicta Buren (Hymenoptera: Formiciddae) invaded and un-invaded habitats].

    PubMed

    Wu, Bi-Qiu; Lu, Yong-Yue; Zeng, Ling; Song, Zhen-Dong; Liang, Guang-Wen

    2009-10-01

    By the methods of bait (honey, peanut oil, sausage, and mealworm larvae) trap, this paper studied the searching time, recruitment time, and recruitment number of ants in 3 typical habitats invaded and un-invaded by red imported fire ant (Solenopsis invicta) in South China, and analyzed the effects of S. invicta invasion on the foraging intensity of native ants. In S. invicta invaded lawn, the searching time of ants for mealworm larvae and peanut oil was significantly shorter, compared with that in S. invicta un-invaded area. Less difference was observed in the searching time for the 4 baits between S. invicta invaded and un-invaded wasteland, but the recruitment time for peanut oil was significantly longer in invaded than in un-invaded area. The searching time and recruitment time of the ants for the 4 baits had less difference between the invaded and un-invaded litchi orchard. 30 min after setting bait traps, the recruitment number of S. invicta workers on peanut oil, mealworm larvae, and sausage in invaded lawn, and on peanut oil in invaded wasteland was larger than that of native ants, but no significant difference was found in the recruitment number of S. invicta workers and native ants on the baits in invaded litchi orchard.

  13. Modeling and analysis of UN TRISO fuel for LWR application using the PARFUME code

    NASA Astrophysics Data System (ADS)

    Collin, Blaise P.

    2014-08-01

    The Idaho National Laboratory (INL) PARFUME (PARticle FUel ModEl) code was used to assess the overall fuel performance of uranium nitride (UN) tristructural isotropic (TRISO) ceramic fuel under irradiation conditions typical of a Light Water Reactor (LWR). The dimensional changes of the fuel particle layers and kernel were calculated, including the formation of an internal gap. The survivability of the UN TRISO particle was estimated depending on the strain behavior of the constituent materials at high fast fluence and burn-up. For nominal cases, internal gas pressure and representative thermal profiles across the kernel and layers were determined along with stress levels in the inner and outer pyrolytic carbon (IPyC/OPyC) and silicon carbide (SiC) layers. These parameters were then used to evaluate fuel particle failure probabilities. Results of the study show that the survivability of UN TRISO fuel under LWR irradiation conditions might only be guaranteed if the kernel and PyC swelling rates are limited at high fast fluence and burn-up. These material properties have large uncertainties at the irradiation levels expected to be reached by UN TRISO fuel in LWRs. Therefore, a large experimental effort would be needed to establish material properties, including kernel and PyC swelling rates, under these conditions before definitive conclusions can be drawn on the behavior of UN TRISO fuel in LWRs.

  14. Modeling and Analysis of FCM UN TRISO Fuel Using the PARFUME Code

    SciTech Connect

    Blaise Collin

    2013-09-01

    The PARFUME (PARticle Fuel ModEl) modeling code was used to assess the overall fuel performance of uranium nitride (UN) tri-structural isotropic (TRISO) ceramic fuel in the frame of the design and development of Fully Ceramic Matrix (FCM) fuel. A specific modeling of a TRISO particle with UN kernel was developed with PARFUME, and its behavior was assessed in irradiation conditions typical of a Light Water Reactor (LWR). The calculations were used to access the dimensional changes of the fuel particle layers and kernel, including the formation of an internal gap. The survivability of the UN TRISO particle was estimated depending on the strain behavior of the constituent materials at high fast fluence and burn-up. For nominal cases, internal gas pressure and representative thermal profiles across the kernel and layers were determined along with stress levels in the pyrolytic carbon (PyC) and silicon carbide (SiC) layers. These parameters were then used to evaluate fuel particle failure probabilities. Results of the study show that the survivability of UN TRISO fuel under LWR irradiation conditions might only be guaranteed if the kernel and PyC swelling rates are limited at high fast fluence and burn-up. These material properties are unknown at the irradiation levels expected to be reached by UN TRISO fuel in LWRs. Therefore, more effort is needed to determine them and positively conclude on the applicability of FCM fuel to LWRs.

  15. Volvulus du grêle sur paquet d’ascaris: à propos d’un cas

    PubMed Central

    Diouf, Cheikh; Kane, Ahmed; Ndoye, Ndeye Aby; Ndour, Oumar; Faye-Fall, Aimé Lakh; Fall, Mbaye; Alumeti, Désiré Munyali; Ngom, Gabriel

    2016-01-01

    Nous rapportons un cas exceptionnel de volvulus nécrosé de l'intestin grêle dû à des ascaris adultes chez un enfant de 7 ans. A l'admission, l'enfant présentait le tableau d'occlusion intestinale qui évoluait depuis deux jours avec altération de l'état général. La radiographie de l'abdomen sans préparation retrouvait des niveaux hydroaériques de type grêlique et un aspect tigré évoquant le diagnostic d'une occlusion intestinale haute sur masse abdominale. Après la réanimation, le traitement chirurgical consistait en une laparotomie qui avait retrouvé un volvulus nécrosé de l'iléon terminale contenant des ascaris adultes. Une résection du grêle sur environ un mètre emportant le segment nécrosé suivie d'une iléostomie était réalisée. L'évolution a été favorable, l'anastomose iléo-colique fut réalisée quatre semaines plus tard. Au recul de deux ans l'enfant est indemne de tout symptôme. PMID:27795803

  16. Ablation d'un film d'or par laser à excimère

    NASA Astrophysics Data System (ADS)

    Sentis, M.; Hermann, J.; Pereira, A.; Delaporte, Ph.; Marine, W.; Perrière, J.; Bianchi, L.; Galli, R.

    2003-06-01

    Ces travaux de recherche ont été réalisés dans le cadre du projet de développement du Laser MégaJoule (LMJ). Parmi les expériences d'interaction laser - matière à très haut flux, certaines conduiront à un dépôt de particules d'or sur les éléments internes de la chambre d'interaction. Pour nettoyer ce dépôt de particules, la possibilité d'utiliser un procédé automatisé basé sur l'ablation laser a été étudiée. Un modèle numérique simplifié a été développé et une étude expérimentale réalisée sur des échantillons d'acier inoxydable ou de B4C recouverts d'un film d'or d'une épaisseur de ~20 nm déposés par PVD. Ces travaux montrent que plus de 95 % du film d'or peuvent être enlevés avec quelques tirs d'un laser XeCI dès que la densité d'énergie dépasse 3 J/cm^2.

  17. How Do Children Restrict Their Linguistic Generalizations? An (Un-)Grammaticality Judgment Study

    PubMed Central

    Ambridge, Ben

    2013-01-01

    A paradox at the heart of language acquisition research is that, to achieve adult-like competence, children must acquire the ability to generalize verbs into non-attested structures, while avoiding utterances that are deemed ungrammatical by native speakers. For example, children must learn that, to denote the reversal of an action, un- can be added to many verbs, but not all (e.g., roll/unroll; close/*unclose). This study compared theoretical accounts of how this is done. Children aged 5–6 (N = 18), 9–10 (N = 18), and adults (N = 18) rated the acceptability of un- prefixed forms of 48 verbs (and, as a control, bare forms). Across verbs, a negative correlation was observed between the acceptability of ungrammatical un- prefixed forms (e.g., *unclose) and the frequency of (a) the bare form and (b) alternative forms (e.g., open), supporting the entrenchment and pre-emption hypotheses, respectively. Independent ratings of the extent to which verbs instantiate the semantic properties characteristic of a hypothesized semantic cryptotype for un- prefixation were a significant positive predictor of acceptability, for all age groups. The relative importance of each factor differed for attested and unattested un- forms and also varied with age. The findings are interpreted in the context of a new hybrid account designed to incorporate the three factors of entrenchment, pre-emption, and verb semantics. PMID:23252958

  18. Perforation gastrique néonatale spontanée: à propos d'un cas

    PubMed Central

    Naji, Abdelhalim; Elkarout, Yahya; Benajiba, Noufissa

    2015-01-01

    La perforation gastrique néonatale spontanée est rare. Nous rapportons un cas survenu chez un nouveau-né issu d'une grossesse et une naissance sans anomalies, et qui a présenté au deuxième jour de sa vie brutalement une distension abdominale importante, suivie d'une détresse respiratoire nécessitant des mesures de réanimation brèves. La radiographie de l'abdomen sans préparation montrait un pneumopéritoine massif, la laparotomie trouvait une perforation au niveau de l'antre gastrique de 2cm, qui était suturée en un plan. Les suites opératoires étaient simples. L’évolution des perforations gastriques spontanées survenant chez le nouveau-né est habituellement favorable. Sous réserve d'un diagnostic et prise en charge précoce. PMID:26405497

  19. Envenimation scorpionique compliqué d'un accident vasculaire cérébral ischemique

    PubMed Central

    Bibiche, Youssef; Berdai, Adnan; Labib, Smael; Harandou, Mustapha

    2015-01-01

    Les piqûres de scorpion sont dans un certain nombre de pays, un accident fréquemment rencontré, et un risque grave. Au Maroc, les données épidémiologiques établies par le centre anti-poison (CAPM) montrent que les piqûres scorpioniques se placent en tête de toutes les intoxications relevées par le centre (60%). Les envenimations scorpioniques posent un grand problème de santé publique. L'apparition de signes neurologiques lors d'une envenimation scorpionique témoigne d'une envenimation grave et correspond au stade III de l’échelle de sévérité. Nous rapportons le cas d'une envenimation scorpionique compliqué d'un Accident vasculaire cérébral ischémique (AVCI) chez un enfant. PMID:26175806

  20. La sténose urétérale post infectieuse et la mégacalicose: un train qui en cache un autre

    PubMed Central

    Sine, Babacar; Bagayogo, Ndeye Aissatou; Fall, Boubacar; Sow, Yaya; Thiam, Amath; Sarr, Alioune; Zakou, Abdou Razak Hamidou; Faye, Samba Thiapato; Diao, Babacar; Fall, Papa Ahmed; Ndoye, Alain khassim

    2015-01-01

    La mégacalicose est une uropathie malformative rare caractérisée par une dilatation non obstructive des calices avec hypoplasie de la médullaire rénale. Nous rapportons un cas de mégacalicose associée à une sténose urétérale bilatérale d'origine infectieuse. PMID:26977241

  1. Un-Alerted Smoke and Fire: Checklist Content and Intended Crew Response

    NASA Technical Reports Server (NTRS)

    Burian, Barbara K.

    2015-01-01

    An in-flight smoke or fire event is an emergency unlike almost any other. The early cues for un-alerted conditions, such as air conditioning smoke or fire, are often ambiguous and elusive. The checklists crews use for these conditions must help them respond quickly and effectively and must guide their decisions. Ten years ago an industry committee developed a template to guide the content of Part 121 checklists for un-alerted smoke and fire events. This template is based upon a new philosophy about how crews should use the checklists and respond to the events. To determine the degree to which current un-alerted checklists of in-flight smoke or fire comply or are consistent with the guidance outlined in the template, I collected and analysed checklists from North American air carriers.

  2. Cancer du sein historique à propos d'un cas!!! Comment réagir

    PubMed Central

    Laghzaoui, Omar

    2016-01-01

    Le cancer du sein localement avancé est une entité qui se fait rare dans les pays développés alors qu'on continue de recevoir des patientes à un stade avancé dans les pays africains. Nous proposant le cas d'une patiente intellectuelle prise en charge à l'hôpital militaire, Meknès, Maroc; qui a décelé la présence d'un nodule du sein droit par l'autopalpation mais elle n'a consulté le médecin que six mois après, dans un état historique de cancer du sein localement avancé. Le but de notre publication est donc de soulever les anomalies contemporaines aboutissant au retard diagnostic du cancer du sein et de proposer des solutions pour mieux sensibiliser la population. PMID:27642397

  3. A Companion Galaxy to the Poststarburst Quasar UN J1025-0040

    NASA Astrophysics Data System (ADS)

    Canalizo, Gabriela; Stockton, Alan; Brotherton, M. S.; van Breugel, Wil

    2000-01-01

    UN J1025-0040 is a quasar at z=0.6344 that shows an extremely bright post starburst population of age ~400 Myr (Brotherton et al.). Images of UN J1025-0040 show a nearly stellar object 4.2" south-southwest of the quasar. We present imaging and spectroscopy that confirm that this object is a companion galaxy at redshift z=0.6341. We estimate an age of ~800 Myr for the dominant stellar population in the companion. The companion appears to be interacting with the quasar host galaxy, and this interaction may have triggered both the starburst and the quasar activity in UN J1025-0040.

  4. MAX UnMix: A web application for unmixing magnetic coercivity distributions

    NASA Astrophysics Data System (ADS)

    Maxbauer, Daniel P.; Feinberg, Joshua M.; Fox, David L.

    2016-10-01

    It is common in the fields of rock and environmental magnetism to unmix magnetic mineral components using statistical methods that decompose various types of magnetization curves (e.g., acquisition, demagnetization, or backfield). A number of programs have been developed over the past decade that are frequently used by the rock magnetic community, however many of these programs are either outdated or have obstacles inhibiting their usability. MAX UnMix is a web application (available online at http://www.irm.umn.edu/maxunmix), built using the shiny package for R studio, that can be used for unmixing coercivity distributions derived from magnetization curves. Here, we describe in detail the statistical model underpinning the MAX UnMix web application and discuss the programs functionality. MAX UnMix is an improvement over previous unmixing programs in that it is designed to be user friendly, runs as an independent website, and is platform independent.

  5. Una propuesta para el desarrollo de un arreglo de síntesis de apertura

    NASA Astrophysics Data System (ADS)

    Arnal, E. M.

    Los estudios llevados a cabo en la transición del hidrógeno neutro a λ~21-cm han contribuído a incrementar nuestro conocimiento acerca de las propiedades globales del medio interestelar, sea este galáctico o extragaláctico. Avances en este campo han sido provocados, a menudo, por la puesta en servicio de radiotelescopios que poseen una mayor resolución angular. Aquí se presenta una propuesta para desarrollar un nuevo instrumento, un interferómetro, que permitirá abrir nuevas líneas de investigación. Este instrumento combinará la técnica de síntesis de apertura con la de espectroscopía de correlación digital, para alcanzar una resolución angular de 1' y un campo de visión de ~1o.7.

  6. La gigantomastie: à propos d'un cas et revue de la littérature

    PubMed Central

    Mamouni, Nisrine; Erraghay, Sanaa; Oufkir, Aya; Saadi, Hanane; Bouchikhi, Chahrazed; Banani, Abdelaziz

    2014-01-01

    L'hypertrophie virginale ou gigantomastie est une mastopathie rare de cause inconnue. Elle survient au moment de la puberté et se manifeste cliniquement par un accroissement rapide et bilatéral du volume des seins. Les dosages hormonaux sont habituellement normaux et la biopsie du sein montre une accentuation du tissu mésenchymateux. Du fait des complications mécaniques et psychologiques liées aux poids et volume excessifs des seins, un traitement chirurgical rapide et efficace s'impose. Le But est de rapporter un cas rare de gigantomastie juvénile, discuter les éventualités thérapeutiques ainsi que le pronostic. PMID:25419292

  7. Syndrome d'Apert chez un congolais de 60 ans: à propos d'une observation

    PubMed Central

    Ngombe, Léon Kabamba; Kabamba, Christophe Mwamba; Nday, David Kakez; Fundi, Jimmy Ngoie; Kitenge, Tony Kayembe; Numbi, Luboya

    2015-01-01

    Le syndrome d'Apert est une rare acrocéphalosyndactylie caractérisée par une dysmorphie crânio-faciale avec une crâniosténose, une syndactylie aux mains et aux pieds et d'autres malformations cérébrales. La coexistence de plusieurs malformations avec un important lot de préjudices esthétiques constitue la gravité de ce syndrome. Une prise en charge précoce et multidisciplinaire s'avère important. Les auteurs rapportent une observation rare d'un syndrome d'apert chez un patient congolais âgé de 60 ans qui n'a jamais bénéficié d'une prise en charge. Ainsi, cette observation décrit les aspects cliniques et évolutifs de cette affection. PMID:26309466

  8. Quand le bloc axillaire reste la seule alternative chez un enfant de 5 ans

    PubMed Central

    Nakhli, Mohamed Said; Béjaoui, Nawel; Naija, Walid; Mhamdi, Salah; Said, Rachid

    2015-01-01

    Le bloc axillaire par neurostimulation chez l'enfant n'est pas une technique habituelle, surtout avec le développement des techniques d'anesthésie locorégionale échoguidées. Cependant elle peut être une alternative intéressante si l'anesthésie générale est a risque voir même contre indiquée. Nous rapportons le cas d'un bloc axillaire anesthésique chez un enfant de 5 ans porteur d'un kyste hydatique du poumon et une hépatite A sévère proposé pour une fixation de fracture du condyle externe de l'humérus. PMID:26405472

  9. Métastases cutanées révélant un adénocarcinome bronchique

    PubMed Central

    Zemmez, Youssef; Zegmout, Adil; Hamama, Jalal; Bouhamidi, Ahmed; El Amraoui, Mohammed; El Azhari, Jaouad; Boui, Mohamed

    2016-01-01

    Nous rapportons le cas d'un cancer bronchique révélé par des nodules cutanés métastatiques du cuir chevelu. Ce mode de découverte assez fréquent est souvent associé à un mauvais pronostic. Cette observation souligne l'intérêt de rechercher un cancer primitif pulmonaire en cas de localisation secondaire cutanée. PMID:27583066

  10. Métastases intramédulaires d'un adénocarcinome pulmonaire: à propos d'un cas

    PubMed Central

    Naji-Amrani, Hicham; Janah, Hicham; Sqalli, Fatimazahra; Souhi, Hicham; Zegmout, Adil; Elouazzani, Hanane; Rhorfi, Ismail Abderrahmani; Abid, Ahmed

    2015-01-01

    Les métastases de la moelle épinière sont extrêmement rares. Elles surviennent chez 0,1 à 0,4% des patients cancéreux et représentent 1% de toutes les tumeurs de la colonne vertébrale et 1-3% des tumeurs intramédullaires. Le cancer du poumon est le primitif le plus fréquent. Nous rapportons le cas d'un patient de 51 ans, suivi pour un adénocarcinome pulmonaire et qui après la 1ère cure de chimiothérapie a développé des métastases intramédullaires et cérébrales. Une radiothérapie sur la moelle et le cerveau associée à une corticothérapie par voie générale ont été débutées. Le patient est décédé 3 mois après la survenue des métastases intramédullaires. A travers ce nouveau cas de métastases intarmédullaires d'un adénocarcinome pulmonaire et revue de la littérature, les auteurs insistent sur leur rareté ainsi que sur ses difficultés diagnostiques et thérapeutiques. PMID:26029326

  11. Blocage de Coulomb dans une boite quantique laterale contenant un faible nombre d'electrons

    NASA Astrophysics Data System (ADS)

    Gould, Charles

    Dans ce travail on utilise une nouvelle geometrie pour augmenter le controle sur le nombre d'electrons contenus dans une boite quantique laterale, et ainsi atteindre un regime de petit nombre d'electrons. Ces echantillons permettent une etude du blocage de Coulomb quand les electrons sont injectes a partir d'un gaz electronique a deux dimensions (2DEG). Les mesures a faible champ magnetique demontrent la grande flexibilite des echantillons et montrent que l'on peut faire varier le nombre d'electrons dans une boite quantique a partir de plus de 40 electrons jusqu'a un seul electron, ce qui est assez courant dans les boites quantiques verticales, mais ce qui n'avait jamais ete reussi dans une boite quantique laterale. Nos resultats montrent egalement que dans les boites quantiques laterales il est possible de determiner le spin du niveau qui participe au transport a l'aide du phenomene de blocage de spin. De plus, dans certaines circonstances il est meme possible de determiner le spin total de la boite quantique, ce qui peut avoir des applications pratiques dans des domaines tels l'informatique quantique. Les mesures dans le regime de renversement de spin a un champ magnetique plus eleve montrent l'importance des correlations electrons---electrons dans ces boites quantiques, qui menent a des depolarisations et a des structures de spins qui ont un effet sur le transport. En particulier, ces correlations menent a l'existence de niveaux excites de basse energie qui causent une dependance anormale de l'amplitude des pics de blocage de Coulomb en fonction de la temperature. Nos experiences demontrent egalement la possibilite d'utiliser ces boites quantiques comme sondes pour etudier les proprietes du bord d'un 2DEG. Une voie de recherche a etre exploree.

  12. Kyste hydatique de la rate: à propos d'un cas

    PubMed Central

    Oumar, Touré Alpha; Ibrahima, Kâ; Sitor, Sarr Ibrahima; Mamadou, Cissé; Ibrahima, Konaté; Ousmane, Kâ; Madieng, Dieng; Abdarahmane, Dia; Tidiane, Touré Cheikh

    2013-01-01

    Le kyste hydatique de la rate est une affection rare en Afrique sub-saharienne. Il arrive en 3ème position après celui du foie et du poumon. Le traitement est essentiellement chirurgical en dehors d'un traitement médical ayant prouvé son efficacité. Nous rapportons le 1er cas pris en charge au Service de Chirurgie Générale du CHU Le Dantec à Dakar. Il s'agit d'un patient de 33 ans, originaire de Mauritanie, sans antécédent particulier qui nous a été adressé pour prise en charge d'un kyste splénique de découverte fortuite à l’échographie lors d'un bilan de routine avec sérologie hydatique positive à Eccinochoccus granulosa. L'examen clinique était sans particularité. La biologie retrouvait une thrombopénie à 88000 plaquettes/mm3. Le scanner montrait des kystes spléniques avec calcifications occupant plus de la moitié du parenchyme splénique. Il a bénéficié d'une splénectomie totale dont les suites ont été simples. Aucune particularité n’était notée après un suivi d'un an. Le kyste hydatique splénique est rare. Le traitement est chirurgical qu'il soit radical ou conservateur avec de bons résultats. PMID:23717708

  13. Syndrome de Lynch: à propos d'un cas et revue de la litterature

    PubMed Central

    Bouguenouch, Laila; Samri, Imane; Belhassan, Khadija; Sayel, Hanane; Abbassi, Meriame; Bennis, Sanae; Benajah, Dafr Allah; Ibrahimi, Adil; Amarti, Afaf; Ouldim, Karim

    2016-01-01

    Le syndrome de Lynch, ou cancer colorectal héréditaire sans polypose ou HNPCC (hereditary non-polyposis colorectal cancer), est la forme la plus fréquente de cancer colorectal héréditaire. Il conduit à une augmentation de la susceptibilité à développer des cancers, au premier rang le cancer colorectal, le cancer de l'endomètre chez les femmes, et dans une moindre mesure, d'autres cancers (ovaire, intestin grêle, estomac, voies excrétrices urinaires et hépatobiliaires). Ainsi, le risque cumulé de développer un cancer colorectal ou de l'endomètre à l’âge de 80 ans s’élève respectivement à 20 et 40%. Ces cancers sont caractérisés par leur contexte d'atteinte familiale, leur survenue à un âge précoce, ainsi que par le développement de cancers métachrones chez un même individu. Ce syndrome se transmet de manière autosomique dominante. Les gènes dont l'altération est associée à l'existence d'un syndrome HNPCC appartiennent à la famille des gènes de réparation des mésappariements de l'ADN (DNA mismatch repair ou MMR): MSH2, MLH1 et MSH6 sont impliqués, par ordre décroissant de fréquence, dans respectivement 35%, 25% et 2% des cas. Une surveillance coloscopique et gynécologique est proposée aux personnes porteuses d'une mutation constitutionnelle du gène MSH2, MLH1 ou MSH6. Nous rapportons une des premières observations marocaines d'un syndrome de Lynch dont la mutation constitutionnelle du gène MLH1 a été identifiée chez un des membres de la famille atteint d'un cancer du côlon. Suite à la demande d'autres sujets sains de la même famille, un diagnostic presymptomatique a été effectué conduisant à une stratégie de surveillance adaptée. A travers notre observation nous illustrons le rôle de l'oncogénétique dans la prise en charge des patients cancéreux et de leurs familles. PMID:27642480

  14. UN Method For The Critical Slab Problem In One-Speed Neutron Transport Theory

    NASA Astrophysics Data System (ADS)

    Öztürk, Hakan; Güngör, Süleyman

    2008-11-01

    The Chebyshev polynomial approximation (UN method) is used to solve the critical slab problem in one-speed neutron transport theory using Marshak boundary condition. The isotropic scattering kernel with the combination of forward and backward scattering is chosen for the neutrons in a uniform finite slab. Numerical results obtained by the UN method are presented in the tables together with the results obtained by the well-known PN method for comparison. It is shown that the method converges rapidly with its easily executable equations.

  15. L’éléphantiasis vulvo-clitoridien: à propos d'un nouveau cas

    PubMed Central

    Sine, Babacar; Bagayogo, Ndeye Aissatou; Thiam, Amath; Sarr, Alioune; Sow, Yaya; Fall, Boubacar; Zakou, Abdou Razak Hamidou; Faye, Samba Thiapato; Diao, Babacar; Fall, Papa Ahmed; Ndoye, Alain khassim; Ba, Mamadou

    2015-01-01

    L’éléphantiasis vulvo-clitoridien d'origine filarienne est une affection très rare. Nous rapportons un nouveau cas chez une femme de 33 ans suivie dans un service de Maladies Infectieuses pour filariose lymphatique. Elle avait une masse vulvo-clitoridienne qui évoluait depuis plus de 10 ans. Une résection clitoridienne et une plastie vulvaire a été réalisée. Les résultats fonctionnels et esthétiques étaient satisfaisants. PMID:26889314

  16. Kyste paratubaire tordu: à propos d'un cas rare de diagnostique difficile

    PubMed Central

    Benkirane, Saad; Alaoui, Fatimazohra Fdili; Chaara, Hekmat; Bougern, Hakima; Melhouf, Moulay Abdelilah

    2014-01-01

    Les kystes para tubaires sont des lésions fréquentes, et peuvent être responsables de complications à type de torsion d'annexe qui est rarissime et difficile à diagnostiquer. Cette pathologie est souvent confondue à une torsion ovarienne, la prise en charge dans les deux cas nécessite une intervention chirurgicale en urgence afin de tenter de conserver l'annexe. Nous rapportons un cas rare d'une jeune patiente opérée d'un kyste para tubaire bénin tordue de diagnostic difficile. PMID:25667687

  17. U(N) invariant dynamics for a simplified loop quantum gravity model

    NASA Astrophysics Data System (ADS)

    Borja, Enrique F.; Díaz-Polo, Jacobo; Garay, Iñaki; Livine, Etera R.

    2011-09-01

    The implementation of the dynamics in Loop Quantum Gravity (LQG) is still an open problem. Here, we discuss a tentative dynamics for the simplest class of graphs in LQG: Two vertices linked with an arbitrary number of edges. We use the recently introduced U(N) framework in order to construct SU(2) invariant operators and define a global U(N) symmetry that will select the homogeneous/isotropic states. Finally, we propose a Hamiltonian operator invariant under area-preserving deformations of the boundary surface and we identify possible connections of this model with Loop Quantum Cosmology.

  18. Application d'une technique de modelisation aerodynamique conceptuelle sur la simulation d'un pilote automatique a commande optimale pour un avion d'affaires

    NASA Astrophysics Data System (ADS)

    Pollender-Moreau, Olivier

    Ce document présente, dans le cadre d'un contexte conceptuel, une méthode d'enchaînement servant à faire le lien entre les différentes étapes qui permettent de réaliser la simulation d'un aéronef à partir de ses données géométriques et de ses propriétés massiques. En utilisant le cas de l'avion d'affaires Hawker 800XP de la compagnie Hawker Beechcraft, on démontre, via des données, un processus de traitement par lots et une plate-forme de simulation, comment (1) modéliser la géométrie d'un aéronef en plusieurs surfaces, (2) calculer les forces aérodynamiques selon une technique connue sous le nom de Vortex Lattice Method, (3) construire un modèle de vol servant à la simulation des aéronefs pour leur enveloppe de vol en ajoutant des fonctions supplémentaires, (4) construire un modèle de turbosoufflante simplifié, (5) développer un algorithme d'équilibre (trim) du mouvement longitudinal, (6) développer des algorithmes de contrôle à commande moderne, (7) développer certaines fonctions d'un système de pilotage automatique, et (8) rassembler le tout sous une même plate-forme de simulation. Afin de supporter ce travail, une application publique Matlab, connue sous le nom de Tornado, est utilisée conjointement avec d'autres fonctions pour la conception du modèle de vol aérodynamique. D'ailleurs, il sera démontré que le modèle de vol, quoiqu'il soit quand même crédible, ne concorde pas tout à fait avec les données de référence. Par contre, puisque le modèle des moteurs fonctionne bien, que l'algorithme d'équilibrage du mouvement longitudinal fonctionne bien et que les pôles des systèmes dynamiques concordent avec la littérature, les tests dynamiques effectués au sein de la plate-forme de simulation permettent d'obtenir des résultats fonctionnels et crédibles. D'ailleurs, deux systèmes d'augmentation de la stabilité basés sur la méthode de contrôle moderne LQR et couvrant l

  19. Elaboration d'un environnement d'experimentation en simulation incluant un cadre theorique pour l'apprentissage de l'energie des fluides

    NASA Astrophysics Data System (ADS)

    Cervera, Daniel

    Dans cette these, nous presentons la demarche et les diverses etapes qui nous ont conduits a l'elaboration d'un environnement d'experimentation en simulation assistee par ordinateur, incluant un cadre theorique, susceptible d'ameliorer l'apprentissage des concepts relies aux phenomenes qui se produisent dans les systemes technologiques fermes impliquant des fluides (gaz et liquides), tels les systemes hydrauliques et pneumatiques industriels, les systemes de refrigeration, de climatisation et de chauffage. Ces phenomenes ne sont pas directement observables et leur evolution obeit aux interactions complexes qui se produisent a l'interieur des systemes, ce qui leur confere un caractere particulierement abstrait et difficile a comprendre. Notre demarche a consiste a concevoir cet environnement d'apprentissage a partir d'une situation problematique qui se caracterise notamment par la presence de fausses representations conceptuelles chez les etudiants et par la complexite des phenomenes impliques dans les systemes en question. Nous avons conceptualise un environnement d'apprentissage interactif d'inspiration essentiellement constructiviste, base sur l'experimentation et la modelisation didactique et qui permet a l'etudiant d'observer simultanement et en temps reel le comportement des systemes et l'evolution des variables au moyen de graphiques. Aussi, nous avons elabore un cadre theorique pour l'apprentissage de l'energie des fluides, de nature semblable a celui qui existe pour les circuits electriques. Ce cadre theorique explicite les regles qui sous-tendent la maniere dont les fluides se distribuent dans les circuits et permet d'articuler une analyse du comportement des systemes. Nous avons realise deux prototypes de l'environnement d'apprentissage. Le premier a permis de verifier la faisabilite technologique et l'interet didactique des principales orientations du projet. Le deuxieme prototype a ete concu et realise dans le cadre d'une entente de partenariat de type

  20. Gibbosité vertébrale congénitale évoquant un mal de Pott chez un nouveau-né de mère tuberculeuse: à propos d'un cas et revue de la literature

    PubMed Central

    Katamea, Tina; Mukuku, Olivier; Luboya, Oscar Numbi

    2014-01-01

    Les formes latentes de tuberculose chez la femme enceinte sont associées à un risque élevé de passage à une forme active qui augmente le risque de transmission de la mère infectée à l'enfant dans les 3 premières semaines de vie. Nous rapportons un cas de Gibbosité vertébrale congénitale évoquant un mal de Pott chez un nourrisson de mère tuberculeuse, observé à Lubumbashi, en République Démocratique du Congo. PMID:25478046

  1. Conception, instrumentation, modelisation et analyse d'un element de stockage d'energie par chaleur latente

    NASA Astrophysics Data System (ADS)

    Millette, Jocelyn

    Des elements de stockage de chaleur utilisant l'electricite comme source d'energie sont utilises presentement en Europe ou la tarification de l'electricite varie en fonction du temps. Dans un contexte ou la dereglementation du marche de l'electricite s'opere massivement en Amerique du Nord, ce type d'appareil est susceptible d'etre beaucoup plus utilise afin de faire une gestion efficace de la consommation electrique. En assurant un meilleur facteur d'utilisation des installations de production, transport et distribution, les utilites pourront etre plus competitives. Les appareils disponibles sur le marche stockent l'energie sous forme sensible (ESECS), ce qui amene differents inconvenients: poids considerable, temperature elevee. Un nouveau type d'appareil est propose dans cette etude: un element de stockage d'energie par chaleur latente (ESECL). Cette etude traite donc de la conception de tels appareils. La demarche de conception proposee dans cette etude s'articule autour du choix des materiaux, du choix du concept de l'echangeur de chaleur. A ce sujet, les materiaux a changement de phase (MCP) etant generalement de mauvais conducteur thermique sous forme solide, la surface d'echange doit etre grande afin d'obtenir une puissance de destockage convenable. Le concept retenu est un element multicouches. D'apres la revue de litterature, la conception d'un element de stockage multicouches par chaleur latente n'a jamais ete abordee. Afin de pouvoir calculer les performances d'un ESECL a construire, un modele NTU-epsilon a ete developpe a cette fin. Contrairement. a ce qui est reporte dans la litterature, le modele developpe tient compte de la surchauffe et de la chaleur sensible dans le MCP solide. Afin d'etablir le modele, la convection naturelle dans le MCP liquide est negligee et un regime quasi permanent est considere dans le MCP. Un prototype d'ESECL a ete construit et instrumente dans le but d'eprouver la demarche de conception et de valider le modele developpe

  2. La luxation erecta bilatérale: à propos d'un cas

    PubMed Central

    Madani, Tarik; Hani, Redouane; Karabila, Mohamed Amine; Kharmaz, Mohammed; Ouadghiri, Mohamed El; Lahlou, Abdou; Lamrani, Mly Omar; Bardouni, Ahmed El; Mahfoud, Mustapha; Berrada, Mohamed Saleh; Yaacoubi, Mouradh El

    2015-01-01

    La luxation erecta est une lésion rare, elle est encore plus rare quand elle est bilatérale. Nous rapportons un cas de luxation erecta bilatérale chez un sportif victime d'une chute lors d'une séance de gymnastique. Le patient s'est présenté aux urgences avec une attitude d'abduction irréductible des deux épaules, l'examen vasculo-nerveux était normal. La radiographie a confirmé le diagnostic d'une luxation erecta bilatérale associée à une fracture des deux tubercules majeurs. Le patient a bénéficié d'une réduction orthopédique et d'un bandage coude au corps. Le suivi a montré un score de l'UCLA à 30 points. L'objectif de notre travail est d'insister sur la rareté de la luxation erecta bilatérale et de rappeler sa particularité clinique, thérapeutique et évolutive. PMID:26977225

  3. The {sigma} phase formation in annealed UNS S31803 duplex stainless steel: Texture aspects

    SciTech Connect

    Souza, C.M. Abreu, H.F.G.; Tavares, S.S.M.; Rebello, J.M.A.

    2008-09-15

    The influence of sigma phase precipitation on the texture of austenite in a duplex stainless steel UNS S31803 was investigated. Sigma phase quantification was precisely performed by electron backscattered scanning diffraction (EBSD) for some conditions. It was found that the increase of the sigma phase precipitation enhances the amount of Brass texture in the austenite phase.

  4. The UN Decade of ESD: What Was Achieved in Scotland 2005-2014

    ERIC Educational Resources Information Center

    Watson, Morag

    2015-01-01

    This article explores the policy changes and actions that have taken place in Scotland between 2005 and 2014 in response to the UN Decade of Education for Sustainable Development (DESD). This article examines the development and content of policy documents relating to schools, Further and Higher Education and Community Learning and Development,…

  5. U.N. Secretary General Ban Ki-moon at NREL

    SciTech Connect

    Ki-Moon, Ban

    2011-01-01

    Providing clean, renewable energy to the 1.4 billion people who are living without electricity is the No. 1 priority of the United Nations, the secretary general of the U.N. said during a visit Aug. 24 to the U.S. Department of Energy's National Renewable Energy Laboratory.

  6. Toward a Trans(National) Reading of Ramon "Tianguis" Perez's "Diario de un mojado"

    ERIC Educational Resources Information Center

    Sisk, Christina L.

    2009-01-01

    In Ramon "Tianguis" Perez's "Diario de un mojado", Perez identifies primarily as a "mojado" and a "macuiltianguense" (a person from San Pablo de Macuiltianguis, Oaxaca). The concept of community as elaborated in the diary incorporates macuiltianguenses on both sides of the border. This essay argues that Perez's transnational community must be…

  7. The UN/ESA Workshops on Basic Space Science in the Developing Countries

    NASA Astrophysics Data System (ADS)

    Haubold, H. J.; Wamsteker, W.

    The origin and evolution of the UN/ESA Workshops on Basic Space Science (BSS) is discussed. We highlight here the motivation and results in global terms. The various new insights in the role of BSS in a sustainable development are indicated.

  8. Structural, electronic, and thermodynamic properties of UN: Systematic density functional calculations

    NASA Astrophysics Data System (ADS)

    Lu, Yong; Wang, Bao-Tian; Li, Rong-Wu; Shi, Hongliang; Zhang, Ping

    2010-11-01

    A systematic first-principle study is performed to calculate the lattice parameters, electronic structure, and thermodynamic properties of UN using the local-density approximation (LDA)+ U and the generalized gradient approximation (GGA)+ U formalisms. To properly describe the strong correlation in the U 5 f electrons, we optimized the U parameter in calculating the total energy, lattice parameters, and bulk modulus at the nonmagnetic (NM), ferromagnetic (FM), and antiferromagnetic (AFM) configurations. Our results show that by choosing the Hubbard U around 2 eV within the GGA+ U approach, it is promising to correctly and consistently describe the above mentioned properties of UN. The localization behavior of 5 f electrons is found to be stronger than that of UC and our electronic analysis indicates that the effective charge of UN can be represented as U 1.71+N 1.71-. As for the thermodynamic study, the phonon dispersion illustrates the stability of UN and we further predict the lattice vibration energy, thermal expansion, and specific heat by utilizing the quasiharmonic approximation. Our calculated specific heat is well consistent with experiments.

  9. Bringing the UN Convention on Rights for Persons with Disabilities to Life in Ireland

    ERIC Educational Resources Information Center

    Quinn, Gerard

    2009-01-01

    This article provides an account of the UN Convention on the Rights of Persons with Disabilities. It describes why the Convention is important in asserting and safeguarding the rights of persons with disabilities and outlines its core values. It explores the nature of rights in the Convention with an account of the Convention as a blueprint for…

  10. 49 CFR 173.301b - Additional general requirements for shipment of UN pressure receptacles.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... valves and pressure relief devices. Except for Division 2.2 permanent gases, each UN pressure receptacle... PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS... valve materials as prescribed for metallic materials in ISO 11114-1 (IBR, see § 171.7 of this...

  11. Cancer métaplasique du sein: à propos d'un cas

    PubMed Central

    Babahabib, Moulay Abdellah; Chennana, Adil; Hachi, Aymen; Kouach, Jaoud; Moussaoui, Driss; Dhayni, Mohammed

    2014-01-01

    Les carcinomes métaplasiques du sein sont des tumeurs rares. Ils constituent un groupe hétérogène de tumeurs définis selon l'organisation mondiale de la santé comme étant un carcinome canalaire infiltrant mais comportant des zones de remaniements métaplasiques (de type épidermoïde, à cellules fusiformes, chondroïde et osseux ou mixte), qui varient de quelques foyers microscopiques à un remplacement glandulaire complet. Les aspects cliniques et radiologiques ne sont pas spécifiques. Le traitement associe la chirurgie, la radiothérapie et la chimiothérapie. L'hormonothérapie n'a pas de place. Le pronostic est sombre. L'histopathologie combinée à l'immunohistochimie permet de poser un diagnostic sure. Etant donné que la prise en charge thérapeutique est limitée, une nouvelle approche moléculaire pourrait modifier cette contribution faible et mal cernée des traitements systémiques classiques. Les patientes atteintes de carcinome métaplasique mammaire pourraient bénéficier de traitements ciblés, ce qui reste à confirmer par des essais cliniques. PMID:25870723

  12. Carcinome colloïde du sein: à propos d'un cas

    PubMed Central

    Laabadi, Kamilia; Jayi, Sofia; Alaoui, Fatimazohra Fdili; Bouguern, Hakima; Chaara, Hikmat; Melhouf, My Abdelilah

    2013-01-01

    Nous rapportons le cas d'une tumeur colloïde du sein chez un homme. Cette situation rare interpelle par son mode de découverte. Nous avons pris en charge un homme de 60 ans atteint d'une lésion rétro-aréolaire droite classée cliniquement T4b N1 M0 et suspecte radiologiquement. L'analyse histologique (microbiopsie) a conclu à un carcinome colloïde muqueux associé à une petite composante canalaire classique de grade I de SBR du sein. Les traitements complémentaires associent mastectomie, curage, chimiothérapie, radiothérapie et hormonothérapie. Le cancer du sein est rare chez l'homme. Le carcinome colloïde est exceptionnel puisqu'il représente seulement 1 à 6% de l'ensemble des cancers du sein. Il est encore plus rare chez l'homme. Ces tumeurs touchent une population spécifique et ont un meilleur pronostic que les autres types prépondérant dans les cancers du sein chez l'homme. A travers cette observation et une revue de la littérature, nous essaierons de discuter les principales caractéristiques anatomo-cliniques et évolutives de cette forme rare du cancer du sein. PMID:24772222

  13. 49 CFR 178.273 - Approval of Specification UN portable tanks.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    .... (a) Application for approval. (1) An owner or manufacturer of a portable tank shall apply for... necessary to ensure that the design meets the relevant specification. (ii) The manufacturer's serial number... representing a single design type. For UN portable tanks, the certificate must refer to the prototype...

  14. Effects of dehydration methods on the characteristics of fibrous networks from un-tanned hides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To improve prospective markets and to secure a viable future for the hides and leather industries, it is important to develop new uses and novel biobased products from hides. We hypothesize collagen fiber networks derived from un-tanned hides can be utilized to prepare high performance green compos...

  15. Effects of dehydration methods on characteristics of fibrous networks from un-tanned hides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To improve prospective markets and to secure a viable future for the hides and leather industries, it is important to develop new uses and novel biobased products from hides. We hypothesize collagen fiber networks derived from un-tanned hides can be utilized to prepare high performance green compos...

  16. Leuconychie transversale induite par la manucurie: y a-t-il un apport de la dermoscopie?

    PubMed Central

    Gallouj, Salim; Mernissi, Fatima Zahra

    2014-01-01

    La leuconychie transversale induite par la manucurie est une leuconychie secondaire au microtraumatisme transmis à la matrice unguéale. Nous rapportant une observation où la dermoscopie avait un intérêt considérable pour l'orientation diagnostic. PMID:25368728

  17. How Do Children Restrict Their Linguistic Generalizations? An (Un- )Grammaticality Judgment Study

    ERIC Educational Resources Information Center

    Ambridge, Ben

    2013-01-01

    A paradox at the heart of language acquisition research is that, to achieve adult-like competence, children must acquire the ability to generalize verbs into non-attested structures, while avoiding utterances that are deemed ungrammatical by native speakers. For example, children must learn that, to denote the reversal of an action, "un-" can be…

  18. The UN Decade of Education for Sustainable Development: Business as Usual in the End

    ERIC Educational Resources Information Center

    Huckle, John; Wals, Arjen E. J.

    2015-01-01

    An analysis of the literature supporting the UN Decade of Education for Sustainable Development and a sample of its key products suggests that it failed to acknowledge or challenge neoliberalism as a hegemonic force blocking transitions towards genuine sustainability. The authors argue that the rationale for the Decade was idealistic and that…

  19. Criminalizing WMD Proliferation: the Role of U.N. Security Council Resolution 1540

    SciTech Connect

    Durbin, Karyn R.; Mladineo, Stephen V.; Vannoni, Michael G.

    2005-05-25

    The United Nations (U.N.) Security Council unanimously passed Resolution 1540 in April 2004. This landmark measure legally charges all U.N. Member States to enact and enforce effective measures to prevent the proliferation of weapons of mass destruction and their means of delivery by preventing illicit trafficking of chemical, biological, radiological, and nuclear (CBRN) materials and related technologies. Revelations regarding the expansiveness of the A.Q. Khan network provided a clear impetus for the Resolution. Resolution 1540 is distinctive because it is the first time the U.N. Security Council has required all Member States to act to prevent the illicit trafficking of CBRN materials and their means of delivery. It is also unique in that it specifically addresses prevention of CBRN proliferation and trafficking among non-state actors. The Resolution has a direct impact on the management of nuclear materials and nonproliferation policy in the future. Consequently, the INMM Nonproliferation and Arms Control Technical Division and the INMM Northeast Chapter initiated a professional workshop on March 15, 2005 to engage topical experts in a discussion of U.N. Security Council Resolution 1540. Although Resolution 1540 is now one year old and the Committee established to monitor its implementation has begun its work, many in the nonproliferation and nuclear materials management communities have not learned of the Resolution or have not yet recognized its significance. This article provides a summary of and perspectives on the workshop discussion that was conducted on a not-for-attribution basis.

  20. Smaller, Quicker, Cheaper: Alternative Strategies for Literacy Assessment in the UN Literacy Decade

    ERIC Educational Resources Information Center

    Wagner, Daniel A.

    2003-01-01

    In the context of the UN Literacy Decade (declared in February 2003), the present paper suggests three parameters that should be considered when new tools for assessment are considered in less developed countries (LDCs), each of which poses a special challenge to international comparative literacy assessment, such as in the International Adult…

  1. Délire dermatozoïque: à propos d'un cas

    PubMed Central

    Jawaher, Masmoudi; Ines, Feki; Rim, Sallemi; Imen, Baati; Abdellaziz, Jaoua

    2013-01-01

    Le délire dermatozoïque est un délire particulier survenant chez les personnes âgées et caractérisé par la présence d'un délire hallucinatoire essentiellement cénesthésique, avec la conviction d’être infesté par des petites bêtes. Ce délire aboutit à des lésions de grattage pouvant être graves, mais sans aucune étiologie organique, et leurrant souvent le dermatologue. Notre observation est originale, par le fait que le patient a été adressé par un ophtalmologue, et faisant étendre le champ du diagnostic à plusieurs spécialités, s'occupant des patients âgés. il s'agit d'un patient âgé de 67 ans, ayant présenté da façon concomitante à une intervention chirurgicale et au mariage de son dernier fils, un délire hallucinatoire avec une conviction d’être attaqué par des moustiques lui suçant le sang. Des lésions d'excoriation cutanée ont été secondaires à ce délire, et ont été à l'origine d'une consultation psychiatrique. L’évolution après six mois de traitement a été marquée par l'enkystement du délire et l'amélioration des lésions cutanées. Réputé rare, le délire dermatozoïque pourrait être déroutant si on ne fait pas le diagnostic positif. Tout clinicien peut être confronté dans sa pratique à ce type de syndrome. Sa compréhension facilite une prise en charge adéquate, basée essentiellement sur un soutien psychologique et un traitement neuroleptique. PMID:24570786

  2. (Un)Caring Communities: Processes of Marginalisation and Access to Formal and Informal Care and Assistance in Rural Russia

    ERIC Educational Resources Information Center

    Kay, Rebecca

    2011-01-01

    The marginality of rural life, understood in structural, economic, political and geographic terms, has been an underlying theme in both historical and contemporary studies of the Russian countryside. Much less attention has been paid to marginality as relational and the moral discourses of (un)belonging and (un)deservingness through which moral…

  3. Un mode révélateur original de la sarcoïdose: syndrome de sweet

    PubMed Central

    Bricha, Myriem; Sqalli, Fatimazzahra; Hammi, Sanae; Bourkadi, Jamal Eddine

    2016-01-01

    Le syndrome de Sweet est une dermatose neutrophilique, le plus souvent idiopathique. L'association d'un syndrome de Sweet et d'une sarcoïdose est rare. Nous rapportons le cas clinique d'un syndrome de Sweet révélant une sarcoïdose. PMID:27279949

  4. 78 FR 70090 - Request for Public Comments on the UN Committee on World Food Security Principles for Responsible...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-22

    ... for Public Comments on the UN Committee on World Food Security Principles for Responsible Agricultural... on the draft UN Committee on World Food Security (CFS) Principles for Responsible Agricultural Investment. Comments received will be shared in full with the CFS for consideration. DATES: All...

  5. The high-pressure effect of an electronic state in uranium compounds: UPtGa5 and UN

    NASA Astrophysics Data System (ADS)

    Nakashima, M.; Haga, Y.; Yamamoto, E.; Tokiwa, Y.; Hedo, M.; Uwatoko, Y.; Settai, R.; Onuki, Y.

    2003-07-01

    We studied the electronic states of two antiferromagnets, UPtGa5 and UN, by measuring the electrical resistivity under pressure. When pressure P is applied, the Néel temperature TN decreases, becoming zero at Pc = 8.0 GPa for UPtGa5 and Pc = 3.5 GPa for UN.

  6. 49 CFR 173.304b - Additional requirements for shipment of liquefied compressed gases in UN pressure receptacles.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... compressed gases in UN pressure receptacles. 173.304b Section 173.304b Transportation Other Regulations...; Preparation and Packaging § 173.304b Additional requirements for shipment of liquefied compressed gases in UN... liquefied compressed gases and gas mixtures as specified in this section. When a liquefied compressed gas...

  7. Estudio de los Institutos Nacionales de la Salud indica que quienes toman café tienen un riesgo meno

    Cancer.gov

    Los adultos mayores que tomaron café, con o sin cafeína, tuvieron un riesgo menor de muerte en general que quienes no tomaron café, según un estudio llevado a cabo por investigadores del Instituto Nacional del Cáncer (NCI), parte de los Institutos Naciona

  8. Children's Rights: Reality or Rhetoric? The UN Convention on the Rights of the Child: The First Ten Years.

    ERIC Educational Resources Information Center

    Bell, Bill; Brett, Rachel; Marcus, Rachel; Muscroft, Sarah

    The UN Convention on the Rights of the Child (CRC), unanimously adopted by the UN General Assembly in 1989, formally recognized children as bearers of rights and established an internationally accepted framework for the treatment of all children. This book examines the progress that has been made in safeguarding children's rights in the past 10…

  9. 49 CFR 173.304b - Additional requirements for shipment of liquefied compressed gases in UN pressure receptacles.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... pressure at 65 °C (149 °F) exceed the test pressure of the UN pressure receptacle. (2) For low pressure... be liquid full at 60 °C. The test pressure of the pressure receptacle must be equal to or greater..., UN1081 must be packaged in a pressure receptacle with a minimum test pressure of 200 bar and a...

  10. 49 CFR 173.304b - Additional requirements for shipment of liquefied compressed gases in UN pressure receptacles.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... pressure at 65 °C (149 °F) exceed the test pressure of the UN pressure receptacle. (2) For low pressure... be liquid full at 60 °C. The test pressure of the pressure receptacle must be equal to or greater..., UN1081 must be packaged in a pressure receptacle with a minimum test pressure of 200 bar and a...

  11. Binary combinations of organophosphorus pesticides exhibit differential toxicity under oxidised and un-oxidised conditions.

    PubMed

    Arora, Sumitra; Kumar, Anu

    2015-05-01

    Acetylcholinesterase (AChE) inhibition has been demonstrated to be useful as a biomarker for exposure to organophosphorus (OP) insecticides in many environments. The objective of this study was to investigate the response of housefly (Musca domestica) head AChE (HF-AChE) exposed to five OPs as individual compounds and their binary mixtures under in vitro conditions. To examine the effects of oxidation on OP potency in the HF-AChE system, bromine water was used as an oxidisng agent. With oxidation, the sensitivity of HF-AChE to chlorpyrifos (CPF), malathion (MLT) and triazophos (TRZ) increased significantly. Monocrotophos (MCP) and profenofos (PRF) did not exhibit any significant differences in toxicity under oxidised and un-oxidised conditions. The toxicological interaction of five organophosphorus pesticides was evaluated using the concentration addition model, the combination index-isobologram equation and the toxic unit approach. All three models provided similar predictions for the 10 binary combinations of OPs under oxidised and un-oxidised conditions. In the present study, the antagonistic effects of the binary combination of OPs (CPF+PRF, CPF+MLT, MCP+MLT, PRF+MLT, MLT+TRZ and PRF+TRZ) were observed under oxidised conditions. This may be due to dispositional and/or receptor antagonism. Most of the binary combinations assayed under un-oxidised conditions exhibited synergistic responses. Triazophos showed very strong synergism in binary combinations with CPF, MCP and PRF un-oxidised conditions. In contrast, under oxidised conditions, only CPF+TRZ exhibited synergism. The results obtained indicate differential toxicity of binary combinations of OPs under oxidised and un-oxidised conditions. This information could be a valuable tool in understanding the mechanisms of OPs interactions and the interpretation of future in vivo studies with mixtures of OP insecticides.

  12. An uncertainty inclusive un-mixing model to identify tracer non-conservativeness

    NASA Astrophysics Data System (ADS)

    Sherriff, Sophie; Rowan, John; Franks, Stewart; Fenton, Owen; Jordan, Phil; hUallacháin, Daire Ó.

    2015-04-01

    Sediment fingerprinting is being increasingly recognised as an essential tool for catchment soil and water management. Selected physico-chemical properties (tracers) of soils and river sediments are used in a statistically-based 'un-mixing' model to apportion sediment delivered to the catchment outlet (target) to its upstream sediment sources. Development of uncertainty-inclusive approaches, taking into account uncertainties in the sampling, measurement and statistical un-mixing, are improving the robustness of results. However, methodological challenges remain including issues of particle size and organic matter selectivity and non-conservative behaviour of tracers - relating to biogeochemical transformations along the transport pathway. This study builds on our earlier uncertainty-inclusive approach (FR2000) to detect and assess the impact of tracer non-conservativeness using synthetic data before applying these lessons to new field data from Ireland. Un-mixing was conducted on 'pristine' and 'corrupted' synthetic datasets containing three to fifty tracers (in the corrupted dataset one target tracer value was manually corrupted to replicate non-conservative behaviour). Additionally, a smaller corrupted dataset was un-mixed using a permutation version of the algorithm. Field data was collected in an 11 km2 river catchment in Ireland. Source samples were collected from topsoils, subsoils, channel banks, open field drains, damaged road verges and farm tracks. Target samples were collected using time integrated suspended sediment samplers at the catchment outlet at 6-12 week intervals from July 2012 to June 2013. Samples were dried (<40°C), sieved (125 µm) and analysed for mineral magnetic susceptibility, anhysteretic remanence and iso-thermal remanence, and geochemical elements Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn (following microwave-assisted acid digestion). Discriminant analysis was used to reduce the number of tracer numbers before un-mixing. Tracer non

  13. Screening of advanced cladding materials and UN-U3Si5 fuel

    NASA Astrophysics Data System (ADS)

    Brown, Nicholas R.; Todosow, Michael; Cuadra, Arantxa

    2015-07-01

    In the aftermath of Fukushima, a focus of the DOE-NE Advanced Fuels Campaign has been the development of advanced nuclear fuel and cladding options with the potential for improved performance in an accident. Uranium dioxide (UO2) fuels with various advanced cladding materials were analyzed to provide a reference for cladding performance impacts. For advanced cladding options with UO2 fuel, most of the cladding materials have some reactivity and discharge burn-up penalty (in GWd/t). Silicon carbide is one exception in that the reactor physics performance is predicted to be very similar to zirconium alloy cladding. Most candidate claddings performed similar to UO2-Zr fuel-cladding in terms of safety coefficients. The clear exception is that Mo-based materials were identified as potentially challenging from a reactor physics perspective due to high resonance absorption. This paper also includes evaluation of UN-U3Si5 fuels with Kanthal AF or APMT cladding. The objective of the U3Si5 phase in the UN-U3Si5 fuel concept is to shield the nitride phase from water. It was shown that UN-U3Si5 fuels with Kanthal AF or APMT cladding have similar reactor physics and fuel management performance over a wide parameter space of phase fractions when compared to UO2-Zr fuel-cladding. There will be a marginal penalty in discharge burn-up (in GWd/t) and the sensitivity to 14N content in UN ceramic composites is high. Analysis of the rim effect due to self-shielding in the fuel shows that the UN-based ceramic fuels are not expected to have significantly different relative burn-up distributions at discharge relative to the UO2 reference fuel. However, the overall harder spectrum in the UN ceramic composite fuels increases transuranic build-up, which will increase long-term activity in a once-thru fuel cycle but is expected to be a significant advantage in a fuel cycle with continuous recycling of transuranic material. It is recognized that the fuel and cladding properties assumed in

  14. Evaluation d'un ecosysteme pastoral sahelien: Apport de la geomatique (Oursi, Burkina Faso)

    NASA Astrophysics Data System (ADS)

    Kabore, Seraphine Sawadogo

    L'objectif principal de cette recherche est la mise au point d'une architecture d'integration de donnees socio-bio-geographiques et de donnees satellitales dans un Systeme d'Information Geographique (SIG) en vue d'une aide a la prise de decisions dans un environnement semi-aride au nord du Burkina Faso. Elle repond a la question fondamentale de l'interpretation des effets des facteurs climatiques et socioeconomiques sur le milieu pastoral. La recherche s'est appuyee sur plusieurs hypotheses de travail: possibilite d'utilisation de modele de simulation, d'approche multicritere et de donnees de teledetection dans un cadre de systeme d'information geographique. L'evolution spatiotemporelle des parametres de productivite du milieu a ete evaluee par approche dynamique selon le modele de Wu et al. (1996) qui modelise les interactions entre le climat, le milieu physique, le vegetal et l'animal pour mieux quantifier la biomasse primaire. A ce modele, quatre parametres ont ete integres par approche floue et multicritere afin de prendre en compte la dimension socioeconomique de la productivite pastorale (apport majeur de la recherche): la sante, l'education, l'agriculture et l'eau. La teledetection (imagerie SPOT) a permis de definir la production primaire a partir de laquelle les simulations ont ete realisees sur 10 annees. Les resultats obtenus montrent une bonne correlation entre biomasse primaire in situ et celle calculee pour les deux modeles, avec toutefois une meilleure efficacite du modele modifie (4 fois plus) dans les zones de forte productivite ou l'on note un taux de surexploitation agricole eleve. A cause de la variabilite spatiale de la production primaire in situ, les erreurs des resultats de simulation (8 a 11%) sont acceptables et montrent la pertinence de l'approche grace a l'utilisation des SIG pour la spatialisation et l'integration des differents parametres des modeles. Les types de production secondaire preconises (production de lait pendant 7 mois ou

  15. L'influence d'un stage d'enseignement dans un musee de sciences naturelles sur le sentiment d'autoefficacite en sciences de futurs enseignants

    NASA Astrophysics Data System (ADS)

    Deblois, Annick

    Cette etude qualitative multicas est ancree dans l'approche sociale-cognitive de la theorie de l'autoefficacite de Bandura (1977). Elle s'interesse a quatre stages a l'enseignement qui se sont deroules au Musee canadien de la nature a Ottawa, Canada, en 2009. L'utilisation de donnees secondaires issues du questionnaire STEBI-B traduit et modifie (Dionne et Couture, 2010) ainsi que des entrevues semi-dirigees ont permis une analyse du changement du sentiment d'autoefficacite en sciences chez les stagiaires. Les elements les plus interessants de cette recherche sont l'apprentissage vicariant et la possibilite de repetition qui favorise une meilleure connaissance de soi et une pratique reflexive. Les resultats, dans l'ensemble positifs, illustrent bien le potentiel d'un tel stage afin de rehausser le sentiment d'autoefficacite en sciences chez des stagiaires en enseignement, particulierement chez ceux qui se destinent a enseigner a l'elementaire puisque ceux-ci ont souvent une formation academique dans un domaine autre que les sciences.

  16. Extraction d'un corps étranger trachéo bronchique à l'aide d'un uretheroscope

    PubMed Central

    Kechna, Hicham; Ouzzad, Omar; Aissaoui, Youness; Nadour, Karim; Zaini, Rachid

    2015-01-01

    Les corps étrangers intratrachéobronchiques (CEITB) sont des accidents fréquents chez les enfants. Dans les pays développés, l'extraction de ces CEITB est réalisée grâce à la fibroscopie bronchique ou à la bronchoscopie rigide. Le recours à la chirurgie est rare. Dans notre contexte, le plateau technique adéquat est inexistant. Des alternatives d'extraction s'imposent afin d’éviter l’évacuation sanitaire, pas toujours à la portée des patients, mais surtout pour faire face à une mort imminente tel est le cas dans notre observation. Nous décrivons l'extraction d'un corps étranger radio-opaque trachéobronchique responsable d'une hypoxie sévère à l'aide d'un uréteroscope. PMID:26090032

  17. Mesure optimale de tilt et déplacement d'un faisceau gaussien

    NASA Astrophysics Data System (ADS)

    Delaubert, V.; Treps, N.; Fabre, C.; Harb, C.; Lam, P. K.; Bachor, H.

    2006-10-01

    Nous réalisons une expérience de mesure optimale de petits déplacements d'un faisceau gaussien TEM{00}, basée sur une détection homodyne employant un oscillateur local TEM{10}. Nous montrons une amélioration de 56% du signal détecté par rapport à une détection à deux zones. Ce nouveau dispositif permet également de mesurer de façon optimale de petites valeurs de tilt, la quantité conjuguée du déplacement. Enfin, nous montrons que la compression du mode TEM{10} du faisceau incident permet une mesure de déplacement au delà de la limite quantique standard.

  18. Manipulation quantique de la lumière par un amplificateur non linéaire

    NASA Astrophysics Data System (ADS)

    Symul, T.; Bencheikh, K.; Levenson, J. A.

    2002-06-01

    Nous proposons un dispositif original, appelé Amplificateur Non Linéaire (ANL), permettant la génération et la manipulation d'états quantiques de la lumière. Ce dispositif permet une compression du bruit quantique de la lumière en dessous de la limite quantique standard plus efficace que celle obtenue par interactions non linéaires du second ordre ou du troisième ordre. Il permet également d'inverser les fluctuations quantiques en intensité de la lumière, et de produire des photons jumeaux ayant des corrélations quantiques plus élevées et plus robustes que ceux produits par un amplificateur paramétrique seul.

  19. Émission de photons uniques par un atome unique piégé

    NASA Astrophysics Data System (ADS)

    Darquié, B.; Beugnon, J.; Jones, M. P. A.; Dingjan, J.; Sortais, Y.; Browaeys, A.; Messin, G.; Grangier, P.

    2006-10-01

    En illuminant un atome unique piégé dans une pince optique de taille micrométrique à l'aide d'impulsions lumineuses résonantes d'une durée de 4 ns, nous avons réalisé une source efficace de photons uniques déclenchés, de polarisation bien définie. Nous avons mesuré la fonction d'autocorrélation temporelle en intensité qui met en évidence un dégroupement de photons presque parfait. Une telle source de photons uniques de haut flux possède des applications potentielles pour le traitement de l'information quantique.

  20. Queer paradox/paradoxical queer: Anne Garréta's Pas un jour (2002).

    PubMed

    Cairns, Lucille

    2007-01-01

    This paper shows how Anne Garréta's Pas un jour (2002) is a decidedly queer text, in both the new and the old sense of that contested epithet. I examine three interrelated concerns central to Pas un jour. First, I analyze Garréta's mediation of desire in general: her own experiences of it; modalities thereof which subvert more 'normative' models of lesbianism; and her convergences with other gay, but male writers and theorists of desire such as Guy Hocquenghem, Gilles Deleuze and Michel Foucault. Second, I interrogate Garréta's dichotomy between desire and friendship, and adumbrate contrasts with Foucauldian theory. Finally, I scrutinize the meaning and value attributed to the particular body of desire with which Garréta is most commonly associated-homosexuality- and their links with those of a contemporary gay male writer, Dominique Fernandez. PMID:17804371

  1. Electronic structure and magnetic and transport properties of single-crystalline UN

    NASA Astrophysics Data System (ADS)

    Samsel-Czekała, M.; Talik, E.; de v. Du Plessis, P.; Troć, R.; Misiorek, H.; Sułkowski, C.

    2007-10-01

    The electronic structure (both valence band and 4f core level spectra) of the cubic monocompound UN in the paramagnetic state was studied by x-ray photoelectron spectroscopy. The experimental results are compared with the results of calculations employing full-potential local-orbital minimum-basis full relativistic method with the spin-orbit coupling included implicitly. The molar susceptibility of a single crystal of antiferromagnetic UN (TN=51K) is reported along three main crystallographic directions between 1.9 and 300K . The observed magnetic characteristics are in agreement with previous studies. The observed small anisotropy in the ordered region is discussed. Results of electronic structure, magnetoresistivity, thermoelectric power, and thermal conductivity as studied on single-crystalline specimens are given and discussed from the viewpoint of dual and spin-density-wave-like character of the 5f electrons.

  2. Antiproton stacking and un-stacking in the Fermilab Recycler Ring

    SciTech Connect

    Chandra Bhat

    2003-06-12

    The Fermilab Recycler Ring (RR) is intended to be used as a future antiproton storage ring for the Run II proton-antiproton collider operation. It is proposed that about 40mA of antiproton beam from the Accumulator Ring will be transferred to the Recycler once for every two to three hours, stacked and cooled. This operation continues for about 10 to 20 hours depending on the collider needs for antiprotons. Eventually, the cooled antiproton beam will be un-stacked from the Recycler and transferred to the Tevatron via the Main Injector. They have simulated stacking and un-stacking of antiprotons in the Recycler using multi-particle beam dynamics simulation code ESME. In this paper they present results of these simulations.

  3. Espectro de radiación derivado de un modelo de colapso protoestelar

    NASA Astrophysics Data System (ADS)

    Coca, S.; Rohrmann, R.

    El exceso de emisión infrarroja en objetos protoestelares es atribuido usualmente a un disco de material en torno al cuerpo central. A pesar del avance alcanzado en la elaboración de modelos, aún existen dificultades para explicar la ley de temperatura del disco necesaria para reproducir las luminosidades y perfiles de energía observados. Nuestra propuesta consiste en determinar la distribución espectral de la radiación derivada de un particular modelo de colapso protoestelar, y estudiar la evolución del espectro desde estadíos tempranos de la contracción gravitatoria. Este plan es orientado a evaluar las propiedades del modelo (distribuciones de masa y temperatura del material circunestelar) por comparación con datos observacionales, a fin de inferir de ello los posibles ajustes requeridos en la teoría actualmente empleada.

  4. Advocating for sexual rights at the UN: the unfinished business of global development.

    PubMed

    Ali, Saida; Kowalski, Shannon; Silva, Paul

    2015-11-01

    Twenty years ago, governments agreed that the right to have control over and decide freely and responsibly on all matters related to one's sexuality, free from coercion, discrimination and violence, is a fundamental human right. Since then, many aspects of sexual rights have been agreed by consensus at the global level, but the term "sexual rights" itself continues to be removed from negotiated outcomes and left out of international agreements, often at the last stages of negotiations. This commentary represents our point of view on the unfinished business of the UN with regards to the fight for sexual rights. Our perspective draws from lessons learned in cross-movement organizing in various regional UN spaces and outlines some of the tactics by conservative forces to push sexual rights to the periphery. The article reaffirms the position that broadening the debate and concepts surrounding sexual rights to be more inclusive, has enormous transformational potential and should inform collective advocacy efforts moving forward. PMID:26718994

  5. L'ostéogenèse imparfaite: à propos d'un cas

    PubMed Central

    Hsayaoui, Najeh; Mbarki, Chaouki; Melliti, Saoussen; El Cadhi, Youssef; Douik, Fatma; Mezghanni, Sana; Oueslati, Hedhili

    2015-01-01

    L'ostéogenèse imparfaite est une maladie héréditaire caractérisée par une fragilité osseuse secondaire à un défaut de synthèse du collagène de type I. Le diagnostic est suspecté devant des signes échographiques évocateurs et confirmé par une étude génétique. Nous rapportons un cas d'ostéogenèse imparfaite de découverte tardive au troisième trimestre chez une patiente qui n'a pas suivi sa grossesse. PMID:26491526

  6. Advocating for sexual rights at the UN: the unfinished business of global development.

    PubMed

    Ali, Saida; Kowalski, Shannon; Silva, Paul

    2015-11-01

    Twenty years ago, governments agreed that the right to have control over and decide freely and responsibly on all matters related to one's sexuality, free from coercion, discrimination and violence, is a fundamental human right. Since then, many aspects of sexual rights have been agreed by consensus at the global level, but the term "sexual rights" itself continues to be removed from negotiated outcomes and left out of international agreements, often at the last stages of negotiations. This commentary represents our point of view on the unfinished business of the UN with regards to the fight for sexual rights. Our perspective draws from lessons learned in cross-movement organizing in various regional UN spaces and outlines some of the tactics by conservative forces to push sexual rights to the periphery. The article reaffirms the position that broadening the debate and concepts surrounding sexual rights to be more inclusive, has enormous transformational potential and should inform collective advocacy efforts moving forward.

  7. Volumineux corps étranger intra-rectal: à propos d'un cas

    PubMed Central

    Mazine, Khalid; Bouassria, Abdesslam; Elbouhaddouti, Hicham; Mouaqit, Ouadii; Benjelloun, Elbachir; Ousadden, Abdelmalek; Mazaz, Khalid; Taleb, Khalid Ait

    2014-01-01

    L'insertion d'objets dans le rectum est peu courante dans les pays au contexte socio-culturel tels que le Maroc. Elle se caractérise par la gravité des complications éventuelles et les différentes possibilités thérapeutiques. Nous rapportons le cas d'un patient, ayant eu une incarcération d'un énorme objet introduit volontairement par voie anale, cet objet étant soigneusement façonné par le patient. Il a bénéficié d'une extraction manuelle. Cette dernière permet, quand elle est possible, d’éviter la chirurgie qui s'impose en cas d’échec ou de complications. PMID:25489367

  8. Estudio dinámico de un potencial perturbador dependiente de dos parámetros

    NASA Astrophysics Data System (ADS)

    Miloni, O.; Brunini, A.

    El objeto del presente trabajo consiste en el estudio dinámico de un sistema dinámico caracterizado por la función hamiltoniana correspondiente a un satélite planetario perturbado por la acción del Sol y del achatamiento del planeta madre. Cuando dicha Hamiltoniana se promedia respecto de los términos de corto período, esta queda con dos grados de libertad, y su estudio puede ser realizado con las herramientas clásicas de la dinámica no-lineal. Se tratará de determinar regiones regulares y caóticas de movimiento. En el caso de estas últimas, es de particular interés la determinación de su orígen.

  9. U(N) and holomorphic methods for LQG and Spin Foams

    NASA Astrophysics Data System (ADS)

    Borja, E. F.; Diaz Polo, J.; Garay, I.

    The U(N) framework and the spinor representation for loop quantum gravity are two new points of view that can help us deal with the most fundamental problems of the theory. Here, we review the detailed construction of the U(N) framework explaining how one can endow the Hilbert space of N-leg intertwiners with a Fock structure. We then give a description of the classical phase space corresponding to this system in terms of the spinors, and we will study its quantization using holomorphic techniques. We take special care in constructing the usual holonomy operators of LQG in terms of spinors, and in the description of the Hilbert space of LQG with the different polarization given by these spinors.

  10. Méningo-vascularite bactérienne révélant un adénome hypophysaire

    PubMed Central

    Bouchal, Siham; Razzouki, Hanane; Elkhyat, Salma Ibn; Maaroufi, Mustafa; El Ouali, Ouarda; Messouak, Ouafae; Belahsen, Mohammed Faouzi

    2015-01-01

    Un macroadénome à prolactine se présente généralement par un syndrome hormonal associé à un syndrome tumoral. Une méningite bactérienne compliquant un macroprolactinome en dehors de toute thérapie médicale ou chirurgicale est rarement rapporté dans la littérature. Mme R.C âgée de 48 ans s'est présentée aux urgences pour trouble de conscience fébrile. La ponction lombaire a révélé une méningite bactérienne. L'imagerie cérébrale a mis en évidence un aspect de vascularite cérébrale et un processus de la loge sellaire avec lyse du plancher faisant évoquer une brèche ostéoméningée. Le bilan biologique a montré une hyperprolactinémie à 200 mg/dl. La patiente est mise sous antibiothérapie à dose méningée et une corticothérapie associée à un traitement par la Cabergoline. Le traitement chirurgical de la brèche ostéoméningée s'est fait par voie endonasale. L’évolution est marquée par une nette amélioration clinique et biologique et l'absence de récidive de la méningite après un recul de 14 mois. Un macroprolactinome peut provoquer une brèche ostéoméningée en dehors de tout traitement médical ou chirurgical et avoir comme première manifestation une méningite infectieuse. PMID:25995804

  11. Astronomía y Física: un matrimonio Sartriano

    NASA Astrophysics Data System (ADS)

    Vucetich, H.

    Desde el siglo XVII, Física y Astronomía han formado un matrimonio similar al de Sartre y Beauvoir: lleno de amores contingentes, pero firme y duradero. En la charla examino tres de los frutos más recientes de este matrimonio: - La confirmación de la Relatividad General con datos astronómicos. - Astrofísica y Física de neutrinos. - Teorías de supercuerdas y astronomía.

  12. The sacrificial cathodic protection of UNS C71500 heat exchanger tubes in Arabian Gulf sea water

    SciTech Connect

    Al-Hashem, A.; Carew, J.A.; Al-Sayegh, A.

    1997-12-01

    A laboratory investigation using a specially designed circulating test rig was carried out to study the effectiveness of achieving complete cathodic protection of UNS C71500 heat exchanger tubes in seawater applications. Results indicated that the galvanic current distribution covered the entire 6m length of the tube. The presence of sulfide ions as pollutants in seawater shifted the galvanic potentials of the tubes to more active potentials and prevented the formation of protective films that normally form.

  13. Pastoral care and counseling with the "un-homeless homeless": understanding cultures of homelessness.

    PubMed

    Snodgrass, Jill

    2014-01-01

    This article presents a subset of findings from a larger study exploring the lived experiences of 16 former residents of a 90-day emergency family shelter program in Los Angeles County. Interpretative phenomenological analysis serves as a qualitative method for understanding the cultural uniqueness of the "un-homeless homeless." The findings offer implications for culturally competent pastoral care and counseling in the context of family homelessness and attend to both the process and content of caregiving.

  14. Ist da jemand? Wie Außerirdische uns entdecken können

    NASA Astrophysics Data System (ADS)

    Heller, R.

    2016-06-01

    Astronomen schlagen vor, sich bei der Suche nach Signalen außerirdischer Zivilisationen auf einen schmalen Bereich am Himmel zu konzentrieren. Von Planeten um Sterne, die in diesem Streifen liegen, würde sich die Erde vergleichsweise leicht entdecken lassen. Sollte es dort intelligentes Leben geben, könnte uns dieses schon längst aufgespürt und eine Botschaft Richtung Erde geschickt haben.

  15. Une cause rare de plexopathie brachiale: une metastase d'un cancer du sein

    PubMed Central

    Maâroufi, Mustapha; Kamaoui, Imane; Boubbou, Meriem; Sqalli, Nadia; Tizniti, Siham

    2014-01-01

    Nous rapportons le cas d'une patiente de 50 ans ayant une histoire de cancer du sein et qui accuse une symptomatologie d'atteinte du plexus brachial. L'IRM montre une masse qui envahie le plexus brachial compatible avec une métastase. L'IRM est très utile pour le diagnostic et l'orientation thérapeutique des plexopathies brachiales chez les femmes présentant un cancer du sein PMID:25360196

  16. An Automatic Uav Mapping System for Supporting un (united Nations) Field Operations

    NASA Astrophysics Data System (ADS)

    Choi, K.; Cheon, J. W.; Kim, H. Y.; Lee, I.

    2016-06-01

    The United Nations (UN) has performed field operations worldwide such as peacekeeping or rescue missions. When such an operation is needed, the UN dispatches an operation team usually with a GIS (Geographic Information System) customized to a specific operation. The base maps for the GIS are generated mostly with satellite images which may not retain a high resolution and the current situation. To build an up-to-date high resolution map, we propose a UAV (unmanned aerial vehicle) based automatic mapping system, which can operate in a fully automatic way from the data acquisition of sensory data to the data processing for the generation of the geospatial products such as a mosaicked orthoimage of a target area. In this study, we analyse the requirements for UN field operations, suggest a UAV mapping system with an operation scenario, and investigate the applicability of the system. With the proposed system, we can construct a tailored GIS with up-to-date and high resolution base maps for a specific operation efficiently.

  17. The UN Convention on International Watercourses and integrated water management: A bridge built

    NASA Astrophysics Data System (ADS)

    Tzatzaki, Vasiliki-Maria

    2008-11-01

    The UN Convention on the Law of the Non Navigational Uses of International Watercourses incorporates principles regarding the management of international water resources. The most important principles are the duty of the riparian states to cooperate, not to cause significant harm, to protect the aquatic environment and to utilize the watercourses reasonably and equitably. The lack of hierarchy between these principles signifies that the necessary step for the sound management of shared natural resources is an integrated approach, which takes into account economic development, human needs and environmental protection. Moreover, the UN Convention proved to be useful for the International Court of Justice (hereinafter ICJ) in the settlement of the Gabcikovo- Nagymaros dispute between Hungary and Slovakia for the Danube River. The Court highlighted the importance of the Convention by reminding the riparian states of their obligation to abide by its principles. On the other hand, the ICJ has used the principles of the Convention in the pending case of Pulp Mills between Uruguay and Argentina. This paper is going to show that the UN Convention is an international legal framework with general guidelines in order to create regional conventions, which promotes integrated water management as a solution to the emerging challenges of international water law and potential future conflicts.

  18. Towards a multiscale approach for assessing fission product behaviour in UN

    NASA Astrophysics Data System (ADS)

    Klipfel, M.; Di Marcello, V.; Schubert, A.; van de Laar, J.; Van Uffelen, P.

    2013-11-01

    Ab initio modelling of fission products (i.e. Nb, Y, Gd, Nd, Zr, Sm, Eu, Ce, Ba, Mo, Sr, Rh, Pd, and Ru) in uranium nitride is carried out by assessing the incorporation, along with their contributions to local swelling of the fuel matrix. Fission products (FP's) in UN have shown to be preferably accommodated at U vacancies in bound [1 0 0]-Schottky defects, nevertheless, similar incorporation energies were found at a single U vacancy. From the investigated incorporation and migration mechanism, we found that FP's in UN predominately migrate along U-U vacancies, since the incorporation energies for all FP are lowest at single U vacancy or at the U vacancy in a Schottky defect. The energy required to induce a migration of a volatile FP from an N vacancy to U vacancy is about 4-5.5 eV. The local volume changes caused by the fission-product substitution have been assessed by means of DFT and combined with the fission-product concentrations obtained by means of neutron calculations (SCALE) to predict fission product swelling in UN. The linear swelling of nitride fuel resulting from these calculations, and the assumption that fission products do not interact and form secondary phases, leads to a reasonable estimation for the swelling rate as a function of burn-up (or time) when compared with empirical correlations in the open literature.

  19. Enzyme directed formation of un-natural side-chains for covalent surface attachment of proteins.

    PubMed

    Cho, Hwayoung; Jaworski, Justyn

    2014-10-01

    The covalent immobilization of proteins onto surfaces is an essential aspect of several fields of research, including proteomics, sensing, heterogeneous biocatalysis, and more broadly biotechnology. Site-specific, covalent attachment of proteins has been achieved in recent years by the use of expanded genetic codes to produce proteins with controlled placement of un-natural amino acids bearing bio-orthogonal functional groups. Unfortunately, the complexity of developing such systems is impractical for most laboratories; hence, a less complicated approach to generating un-natural amino acid side-chains has been employed. Utilizing a straightforward reaction with formylglycine generating enzyme, we use the site-specific modification of engineered proteins to yield un-natural amino acid side-chains for protein immobilization. Using this approach, we demonstrate the controlled immobilization of various enzymes onto a variety of amine coated surfaces. Our results reveal reusability of the immobilized enzymes via this strategy, and furthermore, we find the activity of the immobilized enzymes to remain even after a month of use indicating significant stability of the linkage.

  20. Abdomen aigu sur une torsion de rate ectopique: à propos d'un cas

    PubMed Central

    Khalid, Elhattabi; Fatimazahra, Bensardi; Rachid, Lefriyekh; Abdelaziz, Fadil; Mohamed, Lahkim; Nadia, Benissa; Driss, Khaiz; Saad, Berrada; Najib, Zerouali Ouariti

    2012-01-01

    La rate ectopique est une entité rare dont l'incidence est mal connue. La torsion de son pédicule est une complication grave, qui doit bénéficier d'un diagnostic précoce; évitant ainsi la splénectomie surtout chez des patients jeunes. Nous rapportons le cas d'une patiente âgée de 39 ans; admise aux urgences dans un tableau d'abdomen aigu chirurgical, l'examen clinique, l’échographie et la tomodensitométrie abdominale ont contribué au diagnostic de torsion d'une rate ectopique en position hypogastrique, la splénectomie a été réalisée devant la découverte peropératoire de taches de nécrose sur la rate tordue. Le diagnostic de torsion d'une rate ectopique doit être suspecté devant l'association d'un abdomen aigu et la palpation d'une masse abdominale. L’échographie et la tomodensitométrie abdominale confirment le diagnostic. Le traitement est chirurgical; il consiste en une splénopexie qui est plus approprié. En présence de nécrose, la splénectomie doit être réalisée aussi bien par voie laparoscopique que par laparotomie. PMID:22655096

  1. Modeling Carbon Dioxide, pH and Un-Ionized Ammonia Relationships in Serial Reuse Systems

    USGS Publications Warehouse

    Watten, Barnaby J.; Rust, Michael; Colt, John

    2009-01-01

    In serial reuse systems, excretion of metabolic carbon dioxide has a significant impact on ambient pH, carbon dioxide, and un-ionized ammonia concentrations. This impact depends strongly on alkalinity, water flow rate, feeding rate, and loss of carbon dioxide to the atmosphere. A reduction in pH from metabolic carbon dioxide can significantly reduce the un-ionized ammonia concentration and increase the carbon dioxide concentrations compared to those parameters computed from influent pH. The ability to accurately predict pH in serial reuse systems is critical to their design and effective operation. A trial and error solution to the alkalinity–pH system was used to estimate important water quality parameters in serial reuse systems. Transfer of oxygen and carbon dioxide across the air–water interface, at overflow weirs, and impacts of substrate-attached algae and suspended bacteria were modeled. Gas transfer at the weirs was much greater than transfer across the air–water boundary. This simulation model can rapidly estimate influent and effluent concentrations of dissolved oxygen, carbon dioxide, and un-ionized ammonia as a function of water temperature, elevation, water flow, and weir type. The accuracy of the estimates strongly depends on assumed pollutional loading rates and gas transfer at the weirs. The current simulation model is based on mean daily loading rates; the impacts of daily variation loading rates are discussed. Copies of the source code and executable program are available free of charge.

  2. Modeling carbon dioxide, pH, and un-ionized ammonia relationships in serial reuse systems

    USGS Publications Warehouse

    Colt, J.; Watten, B.; Rust, M.

    2009-01-01

    In serial reuse systems, excretion of metabolic carbon dioxide has a significant impact on ambient pH, carbon dioxide, and un-ionized ammonia concentrations. This impact depends strongly on alkalinity, water flow rate, feeding rate, and loss of carbon dioxide to the atmosphere. A reduction in pH from metabolic carbon dioxide can significantly reduce the un-ionized ammonia concentration and increase the carbon dioxide concentrations compared to those parameters computed from influent pH. The ability to accurately predict pH in serial reuse systems is critical to their design and effective operation. A trial and error solution to the alkalinity-pH system was used to estimate important water quality parameters in serial reuse systems. Transfer of oxygen and carbon dioxide across the air-water interface, at overflow weirs, and impacts of substrate-attached algae and suspended bacteria were modeled. Gas transfer at the weirs was much greater than transfer across the air-water boundary. This simulation model can rapidly estimate influent and effluent concentrations of dissolved oxygen, carbon dioxide, and un-ionized ammonia as a function of water temperature, elevation, water flow, and weir type. The accuracy of the estimates strongly depends on assumed pollutional loading rates and gas transfer at the weirs. The current simulation model is based on mean daily loading rates; the impacts of daily variation loading rates are discussed. Copies of the source code and executable program are available free of charge.

  3. L'actinomycose cervico-faciale: à propos d'un cas

    PubMed Central

    Badre, Bouchra; Essaadi, Mustapha; El Arabi, Samira

    2013-01-01

    L'actinomycose est une infection spécifique rare, non contagieuse. Elle se localise dans la région des maxillaires, avec une évolution chronique. Le germe le plus souvent incriminé est Maroc. Nous rapportons le cas d'un enfant âgé de 5 ans, qui a présenté des processus suppuratifs chroniques en rapport avec une actinomycose sous mandibulaire gauche. Le diagnostic de certitude a été porté par l'examen histopathologique. Le traitement de cette infection est chirurgical avec drainage et curetage des lésions, associé à une antibiothérapie à forte dose et à durée prolongée. L'actinomycose peut simuler n'importe quelle affection de la sphère ORL, elle peut prendre en particulier un aspect pseudotumoral égarant de ce fait son diagnostic. Une sensibilisation des médecins à cette pathologie s'impose, pour un diagnostic précoce dont dépend le pronostic. PMID:23785552

  4. Lymphome malin non Hodgkinien primitif du larynx: à propos d'un cas

    PubMed Central

    Elmazghi, Abderrahman; Elkacemi, Hanan; Lalya, Issam; Zaidi, Hanan; Harmouch, Amal; Kanouni, Lamia; Kebdani, Taieb; Hassouni, Khalid; Benjaafar, Noureddine; Elgueddari, Brahim

    2011-01-01

    Le lymphome malin non hodgkinien (LMNH) primitif laryngé est une entité rare qui représente moins de 1% des cancers du larynx. Nous rapportons un nouveau cas, chez un homme de 24 ans qui avait présenté une dysphonie et une dysphagie d'installations progressives. La laryngoscopie a révélé une lésion bourgeonnante de la bande ventriculaire gauche. L'histologie a objectivé un lymphome T, CD3 positif, qui a bien évolué après traitement par quatre cures de CHOP (cyclophosphamide, doxorubicine, vincristine, et prednisone), suivies d'une radiothérapie sur le larynx et le médiastin supérieur à la dose totale de 40Gy. Malgré sa rareté relative, cette pathologie de diagnostic difficile, nécessite une vigilance particulière et devrait être gérée selon les tendances actuelles du traitement pour les LMNH ganglionnaires. PMID:22355427

  5. Association sarcoïdose et maladie de Horton: à propos d'un cas

    PubMed Central

    Marzouk, Sameh; Hriz, Hela; Jallouli, Moez; Cherif, Yosra; Bahloul, Zouhir

    2015-01-01

    La sarcoïdose peut être associée à d'autres maladies inflammatoires. Elle est exceptionnellement associée à une maladie de Horton posant un problème nosologique sur le caractère fortuit ou non de cette association. Nous rapportons l'observation d'une patiente, âgée de 68 ans, chez qui le diagnostic de sarcoïdose avec atteinte rénale, hépatique, oculaire, articulaire et signes généraux a été retenu et ayant été traitée par corticothérapie avec une bonne évolution. 3 ans plus tard elle a présenté des céphalées fronto-temporales associées à une claudication massétérienne et un syndrome inflammatoire biologique. La biopsie de l'artère temporale a conclu à une artérite à cellules géantes. L’évolution a été favorable sous corticothérapie. L'association d'une maladie de Horton à une sarcoïdose suggère un lien éventuel entre ces deux affections. PMID:26213599

  6. Kyste hydatique de la surrénale: à propos d'un cas

    PubMed Central

    Mahmoudi, Ammar; Maâtouk, Mezri; Noomen, Faouzi; Nasr, Mohamed; Zouari, Khadija; Hamdi, Abdelaziz

    2015-01-01

    Le kyste hydatique de la surrénale reste une affection exceptionnelle et une localisation inhabituelle du kyste hydatique, même dans les pays où l'hydatidose sévit à l’état endémique. Nous rapportons un cas de kyste hydatique surrénalien révélé par des douleurs de l'hypochondre droit. Le diagnostic a été évoqué en préopératoire sur les données de la tomodensitométrie abdominale qui avait objectivé une masse kystique surrénalienne droite. La sérologie hydatique était positive. Le traitement chirurgical avait consisté en une résection du dôme saillant et avait permis de conserver la glande. Le kyste était univésiculaire contenant un liquide eau de roche avec une membrane proligère. Les suites opératoires étaient simples. La surveillance à distance, échographique et immunologique, n'avait pas décelé de récidive avec un recul de deux ans PMID:26587122

  7. Un nouveau cristal laser largement accordable le BOYS dopé à l'ytterbium

    NASA Astrophysics Data System (ADS)

    Chénais, S.; Druon, F.; Balembois, F.; Georges, P.; Gaumé, R.; Aka, G.; Viana, B.; Vivien, D.

    2002-06-01

    Nous avons étudié les performances laser en pompage par diode de puissance d'un nouveau cristal : le Sr3Y(BO3)3 (acronyme : BOYS), dopé à l'ytterbium. Son spectre d'émission particulièrement large en fait un matériau particulièrement prometteur pour la réalisation de lasers femtosecondes directement pompés par diode. Ses performances ont été comparées à celles d'un verre phosphate ainsi qu'à celles du cristal d' Yb:GdCOB dans les mêmes conditions. Nous démontrons que, tant du point de vue de l'efficacité laser que de la tenue aux fortes puissances, GdCOB et BOYS sont supérieurs au verre ; le BOYS est de surcroît plus accordable (sur 50 nm), mais son comportement thermique limite a priori son usage à des puissances de pompe modérées.

  8. Les garrots de prélèvement, un drame chez le nourrisson: à propos de 3 cas

    PubMed Central

    Ouangré, Edgar; Bazongo, Moussa; Ouédraogo, Isso; Zida, Maurice; Ouedraogo, Daouda; Sanou, Adama; Bonkoungou, Gilbert Patindé; Doamba, Rodrigue Namékinsba; Zongo, Nayi; Traore, Si Simon

    2016-01-01

    Le délai pour la levée d'un garrot sur un membre est limité, tout retard, surtout après la 3ème heure expose à un risque d'amputation de celui-ci. Notre objectif a été de rapporter trois cas de gangrène ischémique de membre par oubli d'un garrot après un prélèvement sanguin, afin d'interpeler le personnel soignant sur ses dangers. Il s'est agi de trois nourrissons dont deux de 3 mois et un de 5 mois, reçus aux urgences viscérales du CHU-Yalgado Ouédraogo pour tuméfaction du membre thoracique gauche. Dans leurs antécédents, on a noté une pose de garrot pour prélèvement de sang qui a été oublié pendant 24 heures dans deux cas et 48 heures dans un cas. L'examen avait retrouvé un œdème diffus associé à un sphacèle du membre supérieur remontant jusqu'au 1/3 moyen du bras; une abolition des pouls ulnaire et radial ainsi que de la sensibilité de la main dans 2 cas. Dans un cas les signes étaient atténués. Le diagnostic de gangrène ischémique de membre a été retenu dans tous les cas. La biologie réalisée était normale. En urgence, il a été réalisé une amputation trans-humérale dans 2 cas et un débridement associé à une amputation de quatre doigts dans un cas. L’évolution a été simple dans tous les cas. La gangrène sèche iatrogène de membre par garrot en milieu hospitalier ne devrait pas se concevoir. Cela passe par la rigueur dans l'administration des soins et une surveillance régulière et attentive des patients. PMID:27217892

  9. Section traumatique de l'utérus non gravide chez une accidentée de voie publique: à propos d'un cas

    PubMed Central

    Cédrick, Sangwa Milindi; Marius, Kitembo Feruzi; Mireille, Kakinga Zabibu; Nelly, Mukonda Sompo; Chamy, Cham Lubamba; Numbi, Kabamge; Mutomb, Jean Felix

    2015-01-01

    Dans cet article les auteurs rapportent un rare cas de section traumatique d'un utérus non gravide, chez une accidentée de voie publique reçu dans un tableau d'hemopéritoine aux services des urgences de l'hôpital General Provincial de Reference Jason Sendwe. PMID:26113916

  10. Réalisation d'un laser Brillouin monomode pour la réduction de porteuse optique de signaux hyperfréquences

    NASA Astrophysics Data System (ADS)

    Norcia, S.; Tonda-Goldstein, S.; Dolfi, D.; Huignard, J.-P.

    2002-06-01

    A partir d'un laser de pompe à 1,55 μm, on réalise un laser Brillouin monomode. Ce laser permet la mise en oeuvre d'une expérience de réduction dynamique de la porteuse optique d'un signal hyperfréquence.

  11. Voie antérieure transversale dans l'ostéosynthèse d'une fracture type III du processus coronoïde chez un adolescent: à propos d'un cas et revue de literature

    PubMed Central

    Belmoubarik, Amine; Ahed, Karim; Abouchane, Marouane; Mahraoui, Mohamed Amine; Elandaloussi, Yassir; Haddoun, Ahmed Reda; Nechad, Mohamed

    2015-01-01

    Les auteurs rapportent une observation rare d'un jeune adolescent de 17 ans qui a présenté une fracture du processus coronoïde du coude survenue suite à un accident de sport. Il s'agit d'une observation décrivant un abord particulier par voie antérieure transversale permettant un contrôle direct et vissage en compression du fragment déplacé; l’évolution radio clinique était satisfaisante. Nous discuterons à la lumière de la littérature, notre attitude thérapeutique, et l’évolution de ce cadre nosologique à travers l'analyse de cette observation. PMID:26113908

  12. Violences conjugales à Antananarivo (Madagascar): un enjeu de santé publique

    PubMed Central

    Gastineau, Bénédicte; Gathier, Lucy

    2012-01-01

    Introduction La violence conjugale a été étudiée dans beaucoup de pays développés mais peu en Afrique subsaharienne. Madagascar est un pays où ce phénomène est peu documenté. Méthodes En 2007, une enquête sur la violence conjugale à Antananarivo (ELVICA) a été menée sur la violence conjugale envers les femmes dans la capitale malgache. ELVICA a interrogé 400 femmes en union, de 15 à 59 ans. Des informations sur les caractéristiques démographiques, socioéconomiques des couples ont été collectées ainsi que sur les actes de violences physiques des hommes sur leurs épouses. L’objectif de cet article est d’identifier les facteurs de risques de la violence conjugale grave, celle qui a des conséquences sur la santé physique des femmes. Résultats Trente-cinq pour cent des femmes qui ont déclaré avoir subi au moins une forme de violence physique au cours des 12 mois précédent l’enquête. Presque la moitié (46%) des femmes violentées ont déclaré avoir déjà eu des hématomes, et environ un quart (23%) des plaies avec saignement. Vingt-deux pour cent ont déjà dû consulter un médecin. Parmi les nombreuses variables socioéconomiques et démographiques testées, quelques-unes sont associées positivement au risque de violence conjugale grave: le fait pour une femme d’être en union consensuelle et d’avoir une activité professionnelle. Il y aussi un lien entre la violence subie et l’autonomie des femmes (liberté accordée par le mari de travailler, de circuler, de voir sa famille). Conclusion A Madagascar, comme ailleurs, la lutte contre les violences conjugales est un élément majeur de l’amélioration du statut et de la santé des femmes. PMID:22514757

  13. Developpement d'un vibrateur acoustique pour precipiter les defauts latents de circuits electroniques

    NASA Astrophysics Data System (ADS)

    Lafleur, Francois

    2003-08-01

    Le procede de deverminage, ou Environmental Stress Screening (ESS), est employe principalement dans le domaine de l'electronique pour reduire les mortalites infantiles des produits avant leur livraison. Il utilise usuellement des stimulations environnementales telles que les vibrations ou la temperature produites a l'aide d'equipements conventionnels d'essais qui sont tres couteux et difficiles a implanter. Le but de cette recherche est le developpement d'une nouvelle methode d'excitation vibratoire des plaques de circuits electroniques a moindre cout par l'emploi de l'excitation acoustique. Le projet a mene au developpement d'un vibrateur acoustique pouvant etre utilise lors d'implantations du procede ESS en milieu industriel. L'utilisation de cette nouvelle technologie et des methodes novatrices de personnalisation des spectres ESS proposees dans cette these permettent la precipitation de defaillances latentes presentes dans les produits electroniques de facon efficace et securitaire et ce, a moindre cout par rapport aux technologies concurrentes. La methodologie des travaux presentes dans cette these inclus: (1) La generation acoustique des vibrations sur les circuits; (2) L'analyse modale acoustique des circuits par des methodes a reference unique et a references multiples; (3) La precipitation de defauts latents typiques des circuits electroniques; (4) Une methode d'individualisation des spectres vibratoires tenant compte des caracteristiques structurelles des circuits; (5) La presentation de la configuration de l'equipement acoustique et les resultats d'implantation du procede. Nonobstant la fabrication, l'installation et la mise en service d'un equipement en milieu industriel (depuis le mois de mai 2002), ces travaux ont permis l'obtention de trois familles de brevets et la publication de six articles de conference: trois portant sur l'analyse modale a reference unique, un portant sur l'analyse modale a references multiples, un autre portant sur la

  14. Association synchrone d'un cancer du sein bilatéral et d'une tumeur stromale gastro-intestinale: à propos d'un rare cas

    PubMed Central

    Afif, Mohammed; Ouziane, Imane; Kouhen, Fadila; Khalil, Jihane; Elomrani, Fedwa; Elkacemi, Hanan; Kebdani, Tayeb; Errihani, Hassan; Benjaafar, Noureddine

    2015-01-01

    Les tumeurs stromales gastro-intestinales sont les tumeurs mésenchymateuses les plus fréquentes, pourtant, leur association avec les tumeurs du sein sont rares, seulement quelques cas cliniques sont rapportés dans la littérature. Nous rapportons l'observation d'une jeune femme de 41 ans, suivie à l'institut national d'oncologie de Rabat, pour un carcinome canalaire du sein, bilatéral, chez qui le bilan d'extension a objectivé une tumeur stromale de type gastro-intestinale aux dépens de l'estomac. Nous décrivons à travers cette observation les aspects épidémiologiques, cliniques, et les particularités de la prise en charge de cette association rare. PMID:26090003

  15. Complication rare de la coloscopie chez un patient sous anticoagulant: hemopéritoine par rupture d'un hématome sous capsulaire de la rate, cas clinique

    PubMed Central

    Sbai, Hicham; Boukatta, Brahim; El Bouazzaoui, Abderahim; Youssfi, Mounia; Mellouki, Ihsane; Benajeh, Dafr Allah; Bobo, Meriem; Bohadouti, Hicham; Tizniti, Siham; Ibrahimi, Adil; Taleb, Khalid Ait; Kanjaa, Nabil

    2015-01-01

    La coloscopie à visée diagnostique et/ou thérapeutique est un examen invasif fréquemment pratiquée de nos jours. La perforation colique et l'hémorragie digestive en sont les principales complications. La survenue d'un hémopéritoine par rupture d'un hématome sous-capsulaire splénique est une complication extrêmement rare et potentiellement mortelle de la coloscopie. Un traumatisme splénique minime passé inaperçu et la prise d'anticoagulant en sont des facteurs favorisants. Nous présentons le cas d'une rupture d'un hématome sous-capsulaire de la rate après une coloscopie, survenue chez un patient de 70 ans porteur d'une valve mitrale mécanique sous acénocoumarol à dose hypocaogulante. La nécessité d'obtention d'une anti coagulation rapidement efficace et l'instabilité hémodynamique avaient justifiée la réalisation d'une splénectomie. L’évolution était favorable. A travers cette observation clinique nous discutons les mécanismes et les modalités de prise en charge devant cette complication. PMID:26523174

  16. Development of an accident-tolerant fuel composite from uranium mononitride (UN) and uranium sesquisilicide (U3 Si2) with increased uranium loading

    NASA Astrophysics Data System (ADS)

    Ortega, Luis H.; Blamer, Brandon J.; Evans, Jordan A.; McDeavitt, Sean M.

    2016-04-01

    The processing steps necessary to prepare a potential accident-tolerant fuel composite consisting of uranium mononitride (UN) combined with uranium sesquisilicide (U3 Si2) are described. Liquid phase sintering was performed with U3 Si2 as the liquid phase combined with UN powder or UN μ-spheres. Various UN to U3 Si2 ratios were tested which resulted in up to 94% dense pellets. Composite UN-U3 Si2 samples had greater than 30% more uranium content than UO2.

  17. Etude d'un systeme de trigeneration decentralise en climats canadiens

    NASA Astrophysics Data System (ADS)

    Allaire Tanguay, Dominique

    Ce mémoire présente l'étude d'un système de trigénération ou CCHP (combined cooling, heating and power) au gaz naturel fournissant les besoins thermiques à un immeuble à logement typique de 13 étages. Un groupe électrogène permettant de générer de l'électricité tout en fournissant de l'eau chaude assure le chauffage du bâtiment et de l'eau chaude sanitaire tandis qu'une machine à absorption ammoniac-eau permet de transformer cette chaleur en puissance frigorifique afin de climatiser le bâtiment en période chaude. Le modèle de cette machine à absorption a spécialement été conçu pour fonctionner avec une température de désorption basse et permet d'évaluer les performances de telles machines dans des situations hors design. Ce modèle à été vérifié à l'aide d'autres modèles avérés et propose des coefficients de performance de l'ordre de 0,7 à 0,8. L'évaluation des performances horaires de ce système est présentée pour une année standard sous trois climats canadiens. Ces performances sont ensuite comparées aux différentes méthodes employées pour assurer ces besoins ainsi que pour générer l'électricité supplémentaire. Les résultats démontrent d'excellentes performances même lorsque comparées aux plus récentes technologies. Les résultats passent d'une légère augmentation de la consommation de gaz naturel dans un climat chaud comme Toronto à une importante réduction dans un climat froid comme Edmonton. Ce système permet donc de combler les besoins thermiques d'un bâtiment tout en générant de l'électricité dans des périodes de pointes annuelles et possiblement journalières. Plusieurs études dont notamment l'optimisation du système et le couplage à d'autres types de bâtiment permettrait cependant de mieux évaluer les possibilités complètes de la trigénération. Mots-clés : Trigénération, CCHP, Absorption, Ammoniac-eau, cogénération.

  18. Detecting un-authorized genetically modified organisms (GMOs) and derived materials.

    PubMed

    Holst-Jensen, Arne; Bertheau, Yves; de Loose, Marc; Grohmann, Lutz; Hamels, Sandrine; Hougs, Lotte; Morisset, Dany; Pecoraro, Sven; Pla, Maria; Van den Bulcke, Marc; Wulff, Doerte

    2012-01-01

    Genetically modified plants, in the following referred to as genetically modified organisms or GMOs, have been commercially grown for almost two decades. In 2010 approximately 10% of the total global crop acreage was planted with GMOs (James, 2011). More than 30 countries have been growing commercial GMOs, and many more have performed field trials. Although the majority of commercial GMOs both in terms of acreage and specific events belong to the four species: soybean, maize, cotton and rapeseed, there are another 20+ species where GMOs are commercialized or in the pipeline for commercialization. The number of GMOs cultivated in field trials or for commercial production has constantly increased during this time period. So have the number of species, the number of countries involved, the diversity of novel (added) genetic elements and the global trade. All of these factors contribute to the increasing complexity of detecting and correctly identifying GMO derived material. Many jurisdictions, including the European Union (EU), legally distinguish between authorized (and therefore legal) and un-authorized (and therefore illegal) GMOs. Information about the developments, field trials, authorizations, cultivation, trade and observations made in the official GMO control laboratories in different countries around the world is often limited, despite several attempts such as the OECD BioTrack for voluntary dissemination of data. This lack of information inevitably makes it challenging to detect and identify GMOs, especially the un-authorized GMOs. The present paper reviews the state of the art technologies and approaches in light of coverage, practicability, sensitivity and limitations. Emphasis is put on exemplifying practical detection of un-authorized GMOs. Although this paper has a European (EU) bias when examples are given, the contents have global relevance. PMID:22333321

  19. Detecting un-authorized genetically modified organisms (GMOs) and derived materials.

    PubMed

    Holst-Jensen, Arne; Bertheau, Yves; de Loose, Marc; Grohmann, Lutz; Hamels, Sandrine; Hougs, Lotte; Morisset, Dany; Pecoraro, Sven; Pla, Maria; Van den Bulcke, Marc; Wulff, Doerte

    2012-01-01

    Genetically modified plants, in the following referred to as genetically modified organisms or GMOs, have been commercially grown for almost two decades. In 2010 approximately 10% of the total global crop acreage was planted with GMOs (James, 2011). More than 30 countries have been growing commercial GMOs, and many more have performed field trials. Although the majority of commercial GMOs both in terms of acreage and specific events belong to the four species: soybean, maize, cotton and rapeseed, there are another 20+ species where GMOs are commercialized or in the pipeline for commercialization. The number of GMOs cultivated in field trials or for commercial production has constantly increased during this time period. So have the number of species, the number of countries involved, the diversity of novel (added) genetic elements and the global trade. All of these factors contribute to the increasing complexity of detecting and correctly identifying GMO derived material. Many jurisdictions, including the European Union (EU), legally distinguish between authorized (and therefore legal) and un-authorized (and therefore illegal) GMOs. Information about the developments, field trials, authorizations, cultivation, trade and observations made in the official GMO control laboratories in different countries around the world is often limited, despite several attempts such as the OECD BioTrack for voluntary dissemination of data. This lack of information inevitably makes it challenging to detect and identify GMOs, especially the un-authorized GMOs. The present paper reviews the state of the art technologies and approaches in light of coverage, practicability, sensitivity and limitations. Emphasis is put on exemplifying practical detection of un-authorized GMOs. Although this paper has a European (EU) bias when examples are given, the contents have global relevance.

  20. Urethane inhibits genioglossal long-term facilitation in un-paralyzed anesthetized rats

    PubMed Central

    Cao, Ying; Ling, Liming

    2010-01-01

    For ~3 decades, urethane has been (partially or solely) used as a successful anesthetic in numerous respiratory long-term facilitation (LTF) studies, which were performed on anesthetized, paralyzed, vagotomized and artificially ventilated animals of several different species. However, things become complicated when LTF of muscle activity is studied in un-paralyzed animals. For example, a commonly used acute intermittent hypoxia (AIH) protocol failed to induce muscle LTF in anesthetized, spontaneously breathing rats. But muscle LTF could be induced when hypoxic episode number was increased and/or anesthetics other than urethane were used. In these studies however, neither anesthetic nor paralysis was mentioned as a potential factor influencing AIH-induced muscle LTF. This study tested whether urethane inhibits AIH-induced genioglossal LTF (gLTF) in un-paralyzed ventilated rats, and if so, determined whether reducing urethane dose reverses this inhibition. Three groups of adult male Sprague-Dawley rats were anesthetized (Group 1: ~1.6 g·kg−1 urethane; Group 2: 50 mg·kg−1 α-chloralose + 0.9–1.2 g·kg−1 urethane; Group 3: 0.9 g·kg−1 urethane + 200–400 µg·kg−1·min−1 alphaxalone), vagotomized and mechanically ventilated. Integrated genioglossus activity was measured before, during and after AIH (5 episodes of 3-min isocapnic 12% O2, separated by 3-min hyperoxic intervals). The AIH-induced gLTF was absent in Group 1 rats (success rate was only ~1/7), but was present in Group 2 (in 10/12 rats) and Group 3 (in 11/11 rats) rats. The genioglossal response to hypoxia was not significantly different among the 3 groups. Collectively, these data suggest that urethane dose-dependently inhibits gLTF in un-paralyzed anesthetized rats. PMID:20433898

  1. Crevice and pitting corrosion behavior of stainless steels in seawater

    SciTech Connect

    Zaragoza-Ayala, A.E.; Orozco-Cruz, R.

    1999-11-01

    Pitting and crevice corrosion tests in natural seawater were performed on a series of stainless steels (i.e., S31603, N08904, S32304, S31803, S32520, N08925 and S31266) in order to determine their resistance to these types of localized corrosion. Open circuit potential (OCP) measurements for these alloys show for short exposure times an ennoblement in the OCP. After a certain time, occasional fall and rise in the OCP values was observed, which can be related to nucleation and repassivation of pits and/or crevices on the metal surface. Analysis of the electrochemical behavior and microscopic observations shows that only S31603 and S32304 alloys were susceptible to crevice and pitting corrosion, whereas the remaining alloys exhibited good resistance. Pitting potentials determined by the potentiodynamic technique also show S3 1603 and S32304 are susceptible to pitting corrosion under the experimental conditions used in this work.

  2. The ILO and the new UN convention on migrant workers: the past and future.

    PubMed

    Bohning, R

    1991-01-01

    Migrant workers are less protected than nationals against the actions of states and employers. These workers therefore require special global protection of their rights while employed in countries other than their own. Accordingly, the UN International Labor Organization (ILO) is constitutionally charged with developing international measures to protect the interests of migrant workers from developing countries. The ILO, however, had little involvement in molding the International Convention on the protection of the Rights of All Migrants Workers and Members of their Families, adopted by the UN General Assembly in 1990. Instead, final adoption of the Convention stems largely from developing state dissatisfaction with the former 1975 ILO Migrant Workers Convention No. 143, and Mexican and Moroccan government machinations outside of the ILO in support of modifications. Convention No. 143 threatened to sever employment opportunities and hard foreign exchange remittances in North America and western Europe from illegally employed immigrant workers from developing countries. By working in the UN outside of the ILO, developing nations would enjoy automatic majority, and greater potential for success in reforming the Convention. Soon, developing nations squelched a delay tactic proffered by the Swedes, and succeeded in bringing the UN General Assembly to adopt resolution 34/172 in December 1979, which led to the establishment of an Open-Ended Working Group. This group then elaborated the 1990 Convention over 19 sessions. At the expense of the ILO and more developed nations, developing nations successfully challenged and changed the international order to benefit their peoples and national economies. Finally, the paper considers the interests of immigrant businesspeople and asylum seekers during or immediately upon entry to a foreign country, who are not specifically covered by the Convention. While the university of international humanitarian law suggests that

  3. The ILO and the new UN convention on migrant workers: the past and future.

    PubMed

    Bohning, R

    1991-01-01

    Migrant workers are less protected than nationals against the actions of states and employers. These workers therefore require special global protection of their rights while employed in countries other than their own. Accordingly, the UN International Labor Organization (ILO) is constitutionally charged with developing international measures to protect the interests of migrant workers from developing countries. The ILO, however, had little involvement in molding the International Convention on the protection of the Rights of All Migrants Workers and Members of their Families, adopted by the UN General Assembly in 1990. Instead, final adoption of the Convention stems largely from developing state dissatisfaction with the former 1975 ILO Migrant Workers Convention No. 143, and Mexican and Moroccan government machinations outside of the ILO in support of modifications. Convention No. 143 threatened to sever employment opportunities and hard foreign exchange remittances in North America and western Europe from illegally employed immigrant workers from developing countries. By working in the UN outside of the ILO, developing nations would enjoy automatic majority, and greater potential for success in reforming the Convention. Soon, developing nations squelched a delay tactic proffered by the Swedes, and succeeded in bringing the UN General Assembly to adopt resolution 34/172 in December 1979, which led to the establishment of an Open-Ended Working Group. This group then elaborated the 1990 Convention over 19 sessions. At the expense of the ILO and more developed nations, developing nations successfully challenged and changed the international order to benefit their peoples and national economies. Finally, the paper considers the interests of immigrant businesspeople and asylum seekers during or immediately upon entry to a foreign country, who are not specifically covered by the Convention. While the university of international humanitarian law suggests that

  4. Modelizacion, control e implementacion de un procesador energetico paralelo para aplicacion en sistemas multisalida

    NASA Astrophysics Data System (ADS)

    Ferreres Sabater, Agustin

    Cualquier sistema electronico que incluya un procesado o tratamiento de la senal, y ademas, algun tipo de actuador mecanico generalmente necesita, como minimo, dos tensiones diferentes de alimentacion. Excluyendo los sistemas de alimentacion distribuida, la solucion tecnica mas utilizada para proporcionar dos o mas tensiones consiste en las fuentes de alimentacion multisalida. En una fuente de alimentacion multisalida los diferentes circuitos que conforman cada salida comparten un mismo transformador de potencia optimizando coste, masa, y volumen. Las ventajas obtenidas con este procedimiento tienen en su contra el efecto que sobre cada salida individual provocan las demas en su conjunto debido, principalmente, a los efectos de los elementos parasitos de los componentes. Un cambio de carga en una de las salidas produce un transitorio que es visto por todas las demas como un efecto de impedancia cruzada, y al final del transitorio, la tension de cada salida es diferente respecto a la que tenian antes del transitorio. Este ultimo resultado se conoce como regulacion cruzada. La disminucion de los efectos de la regulacion cruzada ha sido objeto de estudio durante los ultimos anos. El objetivo ha sido el desarrollo de distintas estrategias que permiten, desde disminuir los efectos de la regulacion cruzada hasta los niveles deseables, a eliminarla completamente. El resultado final suele suponer una penalizacion sobre el diseno del sistema directamente proporcional al grado de regulacion a conseguir en las distintas salidas. Entre las soluciones propuestas para eliminar la regulacion cruzada las tecnicas de post-regulacion se han consolidado como la opcion mas aceptada ya que, pueden aplicarse a cualquier convertidor y no suponen ninguna complejidad adicional a la hora de plantear el diseno. En esta Tesis Doctoral se abordara el estudio de la tecnica conocida como postregulacion mediante transformador controlado, que si bien se ha empleado en convertidores resonantes, su

  5. National Satellite Land Monitoring Systems for REDD+ : the UN-REDD support to countries

    NASA Astrophysics Data System (ADS)

    Jonckheere, I. G. C.

    2015-12-01

    REDD+, which stands for 'Reducing Emissions from Deforestation and Forest Degradation in Developing Countries' - is a climate mitigation effort and aims to create a financial value for the carbon stored in forests, offering incentives for developing countries to reduce emissions from forested lands and invest in low-carbon paths to sustainable development. The UN-REDD Programme, a collaborative partnership between FAO, UNDP and UNEP launched in September 2008, supports nationally-led REDD+ processes and promotes the imeaningful involvement of all stakeholders, including Indigenous Peoples and other forest-dependent communities, in national and international REDD+ implementation.The Programme supports national REDD+ readiness efforts in partner countries spanning Africa, Asia-Pacific and Latin America, in two ways: (i) direct support to the design and implementation of UN-REDD National Programmes; and (ii) complementary support to national REDD+ action through common approaches, analyses, methodologies, tools, data and best practices. The UN-REDD Programme currently supports 62 partner countries. The UN-REDD Programme gathers technical teams from around the world to develop common approaches, analyses and guidelines on issues such as measurement, reporting and verification (MRV) of carbon emissions and flows, remote sensing, and greenhouse gas inventories. Within the partnership, FAO supports countries on technical issues related to forestry and the development of cost effective and credible MRV processes for emission reductions. While at the international level, it fosters improved guidance on MRV approaches, including consensus on principles and guidelines for MRV and training programmes. It provides guidance on how best to design and implement REDD, to ensure that forests continue to provide multiple benefits for livelihoods and biodiversity to societies while storing carbon at the same time. Other areas of work include national forest assessments and monitoring

  6. All-optical packet header and payload separation for un-slotted optical packet switched networks

    NASA Astrophysics Data System (ADS)

    Ji, Wei; Zhang, Min; Ye, Peida

    2005-11-01

    A novel all-optical header and payload separation technique that can be utilized in un-slotted optical packet switched networks is presented. The technique uses a modified TOAD for packet header extraction with differential modulation scheme and two SOAs that perform a simple XOR operation between the packet and its self-derived header to get the separated payload. The main virtue of this system is simple structure and need not any additional continuous pulses. Through numerical simulations, the operating characteristics of the scheme are illustrated. In addition, the parameters of the system are discussed and designed to optimize the operation performance.

  7. Dynamics for a simple graph using the U(N) framework for loop quantum gravity

    NASA Astrophysics Data System (ADS)

    Borja, Enrique F.; Díaz-Polo, Jacobo; Freidel, Laurent; Garay, Iñaki; Livine, Etera R.

    2012-05-01

    The implementation of the dynamics in loop quantum gravity (LQG) is still an open problem. Here, we discuss a tentative dynamics for the simplest class of graphs in LQG: Two vertices linked with an arbitrary number of edges. We find an interesting global U(N) symmetry in this model that selects the homogeneous/isotropic sector. Then, we propose a quantum Hamiltonian operator for this reduced sector. Finally, we introduce the spinor representation for LQG in order to propose a classical effective dynamics for this model.

  8. Sintering of compacts of UN, (U,Pu)N, and PuN

    DOEpatents

    Tennery, V.J.; Godfrey, T.G.; Bomar, E.S.

    1973-10-16

    >A method is provided for preparing a densified compact of a metal nitride selected from the group consisting of UN, (U,Pu)N, and PuN which comprises heating a green compact of at least one selected nitride in the mononitride single-phase region, as displayed by a phase diagram of the mononitride of said compact, in a nitrogen atmosphere at a pressure of nitrogen less than 760 torr. At a given temperature, this process produces a singlephase structure and a maximal sintered density as measured by mercury displacement. (Official Gazette)

  9. Analisis de Alteraciones EN la Imagen Debidas a Descolimacion de un Telescopio

    NASA Astrophysics Data System (ADS)

    Cobos, F. J.; Galan, M. J.

    1987-05-01

    Podemos considerar, en términos generales, que los espejos de un telescopio tienen una calidad óptica intrínseca, entendiendo por ésta la que se ha obtenido como resultado, fundamentalmente, de la destreza del personal del Taller Optico, que considerará terminadas las superficies ópticas cuando éstas satisfagan los requisitos de diseño y las pruebas de evaluación pertinentes. Debemos esperar que, una vez instalados los espejos en el telescopio, no se altere esta calidad de la óptica por un funcionamiento inadecuado de partes mecánicas del mismo. En los últimos años, en la medida que los problemas de infraestructuratura de nuestros Observatorios se han ido resolviendo, se ha hecho más patente la necesidad de llevar a la instrumentación existente al máximo de su potencial y parte esencial de ésta la conforman los mismos te lescopios. Mejorar la calidad óptica de las imágenes obtenidas con ellos ha hecho que sea prioritario el realizar una investigación más sistemática de sus características. Este trabajo ha tenido como objetivo primordial el usar un programa de diseño óptico, en el caso particular del telescopio UNAM212, con el fin de calcular y obtener gráficamente los diagramas de manchas de imagenes en foco y extrafocales, tanto con la óptica perfectamente alineada como descolimándola (mediante pequenos giros y descentramientos de los espejos). De esta manera, se hizo una evaluación de los efectos que estas alteraciones simuladas producirían en las imágenes focales y extra focales para así poder compararlas con las que realmente se han observado. Asimismo, se ha buscado información bibliográfica, en particular sobre los efectos de giros y descentramientos en las imágenes extrafocales, en lo que se ref iere a la falta de concentricidad de los círculos que forman la "dona" y a la distribución de intensidad luminosa en la misma. De ésta, l futuro un proceso que, haciendo uso de los detectores bidimensionales, nos permita Ilevar a

  10. Volatile compound in cut and un-cut flowers of tetraploid Freesia hybrida.

    PubMed

    Ao, Man; Liu, Baofeng; Wang, Li

    2013-01-01

    The flower volatile compounds (FVCs) of two tetraploid Freesia hybrida (pink-yellow and yellow) cultivars and their cut flowers were analysed by headspace solid-phase microextraction combined with gas chromatography-mass spectrometry. Twelve FVCs were identified in the pink-yellow cultivar, with linalool as the major compound; 30 FVCs were identified in the yellow cultivar, with linalool and terpineol as the two major compounds. The FVCs (>1%) of the two cut flower cultivars were very similar to that of the un-cut flowers, and no significant difference was observed.

  11. Controle sismique d'un batiment en acier de 1 etage par amortisseurs elastomeres et contreventements en Chevron

    NASA Astrophysics Data System (ADS)

    Girard, Olivier

    Actuellement, le principe de dimensionnement a la capacite est fortement utilise dans le domaine du genie parasismique. De maniere simplifiee, cette methode de dimensionnement consiste a dissiper l'energie injectee a une structure lors d'une secousse sismique par la deformation inelastique d'un element structural sacrificiel. Cette methode de dimensionne-ment permet d'obtenir des structures economiques, car cette dissipation d'energie permet de reduire substantiellement les efforts qui se retrouvent a l'interieur de la structure. Or, la consequence de ce dimensionnement est la presence de degats importants a la structure qui suivent a la secousse sismique. Ces degats peuvent engendrer des couts superieurs aux couts d'erection de la structure. Bien entendu, sachant que les secousses sismiques d'importances sont des phenomenes rares, l'ingenieur est pret a accepter ce risque afin de diminuer les couts initiaux de construction. Malgre que cette methode ait permis d'obtenir des constructions economiques et securitaires, il serait interessant de developper un systeme qui permettrait d'obtenir des performances de controle des efforts sismiques comparables a un systeme dimensionne selon un principe de dimensionnement a la capacite sans les consequences negatives de ces systemes. En utilisant les principes d'isolation a la base, il a ete possible de developper un systeme de reprise des forces sismiques (SRFS). qui permet d'obtenir un controle des efforts sismiques concurrentiels tout en gardant une structure completement elastique. Ce systeme consiste u inserer un materiel elastomere entre l'assemblage de la poutre et des contreventements a l'interieur d'un cadre contrevente conventionnel. Cette insertion permet de diminuer substantiellement la rigidite laterale du batiment, ce qui a pour consequence d'augmenter la valeur de la periode fondamentale du batiment dans lequel ces cadres sont inseres. Ce phenomene est appele le saut de periode. Ce saut de periode permet de

  12. Pyélonéphrite xanthogranulomateuse bilatérale focale : à propos d’un cas

    PubMed Central

    El Yacoubi, Souhail; Ziouziou, Imad; Zizi, Mohamed; Jahid, Ahmed; Karmouni, Tariq; El Khader, Khalid; Koutani, Abdellatif; Andaloussi, Ahmed Iben Attya

    2014-01-01

    Résumé Nous présentons l’observation clinique d’un cas rare de pyélonéphrite xanthogranulomateuse (PXG) bilatérale chez un jeune patient âgé de 17 ans. La découverte progressive de l’infection a débuté par l’apparition de lombalgies bilatérales évoluant depuis un mois, sans autre signe associé. L’urotomodensitométrie penchait en faveur de deux masses rénales bilatérales, soit une masse polaire inférieure droite et une masse polaire supérieure gauche, toutes deux de densité tissulaire. Une biopsie échoguidée a suggéré la présence d’une réaction inflammatoire non spécifique. Une néphrectomie partielle polaire inférieure droite a été effectuée devant la forte présomption de tumeurs rénales malignes. Finalement, l’histologie a orienté le diagnostic vers une PXG. Il s’agit, à notre connaissance, du sixième cas de PXG focale bilatérale rapporté dans la littérature. Notre patient a reçu un traitement antibiotique à base de fluoroquinolone pendant un mois. L’évolution clinique s’est avérée bonne, et les lésions visibles à la tomodensitométrie se sont entièrement résorbées au bout d’un mois. Le patient vit toujours après un an et présente une fonction rénale normale. PMID:25295145

  13. Pneumomédiastin compliquant une crise d’éclampsie: à propos d'un cas

    PubMed Central

    Doumiri, Mouhssine; Motiaa, Youssef; Oudghiri, Nezha; Saoud, Anas Tazi

    2014-01-01

    Le pneumomédiastin associé à l'emphysème sous cutané et le pneumothorax, sont des complications rares de la grossesse et surviennent au cours du travail obstétrical. Nous rapportons l'observation d'une parturiente de 25ans, sans antécédent pathologique particulier, admise pour une crise d’éclampsie à 36 semaines d'aménorrhées avec une mort fœtale et trouble de la conscience. L'examen clinique a montré un emphysème sous cutané étendu du visage jusqu’à l'abdomen sans notion de traumatisme et un score de Glasgow à 10. Après mise en condition, traitement de la crise d’éclampsie, stabilisation de la tension artérielle et retour à l’état de conscience, une TDM cervico-thoraco-abdominale a été demandée et a révélé la présence d'un pneumomédiastin important avec un discret pneumothorax droit postérieur et un pneumopéritoine important qui n'ont pas nécessité de drainage pleural. Deux jours après son admission, la patiente a expulsé un mort-né d'un poids de 1800 grammes avec forceps et sans efforts d'expulsions sous analgésie péridurale. Le contrôle radiologique à une semaine a noté une nette diminution de l'emphysème sous cutané et du pneumomédiastin. La patiente a quitté l'hôpital après dix jours. PMID:25838864

  14. Abcès thyroïdien révélant un basedow: à propos d’un cas et revue de la littérature

    PubMed Central

    Chenguir, Meriem; Souldi, Hajar; Loufad, Fatima Zahra; Rouadi, Sami; Abada, Reda; Roubal, Mohamed; Mahtar, Mohamed

    2016-01-01

    L’abcès thyroïdien est une entité clinique très rare. Elle représente 0,1% des pathologies chirurgicales de la thyroïde. Les caractéristiques anatomique et physiologique de la glande lui procurent une résistance vis-à-vis des agents pathogènes. Les infections à Streptococcies et Staphylococcus sont les plus fréquentes. La tuberculose reste rarement rapportée dans la littérature. La survenue de l’infection sur goitre toxique est exceptionnelle. Les auteurs rapportent un cas rare d’abcès thyroïdien révélant un goitre toxique chez un jeune de 22 ans. Il s’est présenté aux urgences ORL pour une tuméfaction cervicale antérieure, légèrement latéralisée à gauche, mobile à la déglutition, associée à des hémoptysies, signes de dysthyroïdie, fièvre et sueurs nocturnes. La TDM cervicale a montré une masse occupant le lobe thyroïdien gauche de contenu liquidien mesurant 2 cm, avec un liquide purulent à la cytoponction. L’examen cyto-bactériologique a mis en évidence un Staphylococcus avec recherche de BK positive. Une radiographie thoracique a été demandée montrant un foyer alvéolaire pulmonaire apical droit. L’étude cytobactériologique des crachats ont isolé le bacille de koch. Le bilan biologique thyroïdien était en faveur d’un Basedow. La prise en charge était médicale comprenait une tri-antibiothérapie par voie parentérale, anti-bacillaire et anti-thyroïdien de synthèse avec bonne évolution. Le diagnostic de la tuberculose doit être évoqué devant toute abcédation thyroïdienne avec un tableau clinique peu bruyant. Il s’agit le plus souvent d’une dissémination hématogène à partir d’un autre foyer de primo-infection surtout pulmonaire. Le traitement est basé sur les anti-bacillaires associé parfois à la chirurgie. PMID:27795799

  15. La rupture intra péritonéale d’un kyste hydatique au cours de la grossesse: à propos d’un cas rare

    PubMed Central

    Rachad, Myriam; Fdili, Fatim Zahra; Slimani, Ouafae; Chaara, Hikmat; Bouguern, Hakima; Melhouf, Moulay Adbelillah

    2012-01-01

    Le kyste hydatique est une parasitose qui sévit à l’état endémique au Maroc. Cependant sa rupture au cours de la grossesse reste rare. Nous rapportons le cas d’une patiente de 23 ans, admise aux urgences en état de choc avec bouffissure du visage sur aménorrhée de 8 semaines, chez laquelle le diagnostic d’hydatidose à la fois hépatique et pelvienne, avec éventuelle rupture de l’un des kystes hépatiques a été posé par la radiologie. Après mesures de réanimation, le traitement chirurgical a été instauré, avec bonne évolution. Nous essayons à partir de ce cas et à travers une revue de littérature, de préciser les difficultés diagnostiques et thérapeutiques rencontrées dans la prise en charge des kystes hydatiques, surtout compliquées, au cours de la grossesse. PMID:22368744

  16. "Homosexuality/Homophobia Is Un-African"?: Un-Mapping Transnational Discourses in the Context of Uganda's Anti-Homosexuality Bill/Act.

    PubMed

    Wahab, Amar

    2016-01-01

    This article un-maps the recent impasse between pro- and antigay mobilization around Uganda's Anti-Homosexuality Act (AHA, 2009-2014). Drawing on scholarly and social media sources, it summarizes the increasing influence of (U.S.) transnational evangelism that has precipitated a state-religious complex of "anticipatory political homophobia" in Uganda. If transnational evangelism against same-sex sexuality in Uganda has generated a strong reaction from global LGBT human-rights advocates, this article critiques this Western homotransnationalist response by analyzing its limited terms of operation, focusing on the ways in which Uganda is hailed into the biopolitical project of a Western queer modernity. The author focuses on the copresence between homotransnationalist mobilization and "homophobic anticipatory countermobilization" as (re)organizing/suturing a global ordering project that is deeply invested in biopolitics and necropolitics. This suggests that the global flashpointing of Uganda in the context of the AHA incites further questions concerning the transnationality of "gay human rights" discourse under neoliberalism.

  17. "Homosexuality/Homophobia Is Un-African"?: Un-Mapping Transnational Discourses in the Context of Uganda's Anti-Homosexuality Bill/Act.

    PubMed

    Wahab, Amar

    2016-01-01

    This article un-maps the recent impasse between pro- and antigay mobilization around Uganda's Anti-Homosexuality Act (AHA, 2009-2014). Drawing on scholarly and social media sources, it summarizes the increasing influence of (U.S.) transnational evangelism that has precipitated a state-religious complex of "anticipatory political homophobia" in Uganda. If transnational evangelism against same-sex sexuality in Uganda has generated a strong reaction from global LGBT human-rights advocates, this article critiques this Western homotransnationalist response by analyzing its limited terms of operation, focusing on the ways in which Uganda is hailed into the biopolitical project of a Western queer modernity. The author focuses on the copresence between homotransnationalist mobilization and "homophobic anticipatory countermobilization" as (re)organizing/suturing a global ordering project that is deeply invested in biopolitics and necropolitics. This suggests that the global flashpointing of Uganda in the context of the AHA incites further questions concerning the transnationality of "gay human rights" discourse under neoliberalism. PMID:26503528

  18. Apoflavodoxin (un)folding followed at the residue level by NMR.

    PubMed Central

    van Mierlo, C. P.; van den Oever, J. M.; Steensma, E.

    2000-01-01

    The denaturant-induced (un)folding of apoflavodoxin from Azotobacter vinelandii has been followed at the residue level by NMR spectroscopy. NH groups of 21 residues of the protein could be followed in a series of 1H-15N heteronuclear single-quantum coherence spectra recorded at increasing concentrations of guanidinium hydrochloride despite the formation of protein aggregate. These NH groups are distributed throughout the whole apoflavodoxin structure. The midpoints of unfolding determined by NMR coincide with the one obtained by fluorescence emission spectroscopy. Both techniques give rise to unfolding curves with transition zones at significantly lower denaturant concentrations than the one obtained by circular dichroism spectroscopy. The NMR (un)folding data support a mechanism for apoflavodoxin folding in which a relatively stable intermediate is involved. Native apoflavodoxin is shown to cooperatively unfold to a molten globule-like state with extremely broadened NMR resonances. This initial unfolding step is slow on the NMR chemical shift timescale. The subsequent unfolding of the molten globule is faster on the NMR chemical shift timescale and the limited appearance of 1H-15N HSQC cross peaks of unfolded apoflavodoxin in the denaturant range studied indicates that it is noncooperative. PMID:10739257

  19. Epanchement pleuro-péricardique liquidien révélant un lymphome lymphoblastique

    PubMed Central

    N'goran, Yves N'da Kouakou; Soya, Kossa Esaïe; Beossin, Sylvanus Koui; Angoran, Ines; Traore, Fatou; Tano, Micesse; Afassinou, Yaovi; Ekou, Arnaud; Koffi, Florent; Yao, Hermann; Kramoh, Euloge Kouadio; Kakou, Maurice Guikahue

    2014-01-01

    L'atteinte cardiaque au cours des lymphomes lymphoblastiques est rare. Il s'agissait d'un patient de 17 ans de race noire qui a été admis pour une douleur médiothoracique. Le patient avait des signes d'insuffisance cardiaque droite; un syndrome d’épanchement pleural liquidien gauche; des adénopathies superficielles et une splénomégalie de type IV de Hackett. La biopsie ganglionnaire a été réalisée pour la confirmation du diagnostic par analyse histologique et immuno-histochimique. Des ponctions pleurale et péricardique ont été effectuées. Le patient a été confié au service d'oncologie pédiatrique pour la chimiothérapie. L’évolution a été marquée par le décès du patient 18 jours après. La manifestation cardiaque est une entité rare et très souvent méconnue.la confirmation histologique est parfois difficile à obtenir du vivant de la plupart des patients. Le pronostic est souvent réservé à court terme. PMID:25419294

  20. Dilemmas of citizenship: young people's conceptions of un/employment rights and responsibilities.

    PubMed

    Gibson, Stephen

    2011-09-01

    This paper draws on the concept of ideological dilemmas in order to explore how a sample of young people constructed potentially contrary themes of liberal citizenship in discussions of un/employment. The study took place in the context of recent policy developments in the UK which have sought to place a renewed emphasis upon notions of responsible citizenship in relation to both welfare and education policy. A total of 58 participants were interviewed in 24 semi-structured group interviews. In response to direct questions on un/employment, participants could resolve dilemmas concerning welfare rights and the responsibility to contribute to society by emphasizing a criterion of effortfulness, thereby adopting a primarily individualistic explanation of unemployment. In other contexts however, this could be replaced by an emphasis on social explanations of unemployment. In particular, participants could treat immigration as a cause of unemployment. These findings are interpreted in terms of people's capacity to construct rhetorical strategies based upon different ideological themes in particular contexts. They are discussed in relation to previous research on social policy discourse and recent debates regarding the appropriateness of seeking to identify ideological themes in discourse.