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Sample records for coated rhenium gasket

  1. Iridium-Coated Rhenium Combustion Chamber

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.; Tuffias, Robert H.; Rosenberg, Sanders D.

    1994-01-01

    Iridium-coated rhenium combustion chamber withstands operating temperatures up to 2,200 degrees C. Chamber designed to replace older silicide-coated combustion chamber in small rocket engine. Modified versions of newer chamber could be designed for use on Earth in gas turbines, ramjets, and scramjets.

  2. Iridium-Coated Rhenium Combustion Chamber

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.; Tuffias, Robert H.; Rosenberg, Sanders D.

    1994-01-01

    Iridium-coated rhenium combustion chamber withstands operating temperatures up to 2,200 degrees C. Chamber designed to replace older silicide-coated combustion chamber in small rocket engine. Modified versions of newer chamber could be designed for use on Earth in gas turbines, ramjets, and scramjets.

  3. Iridium-coated rhenium thrusters by CVD

    NASA Technical Reports Server (NTRS)

    Harding, J. T.; Kazaroff, J. M.; Appel, M. A.

    1989-01-01

    Operation of spacecraft thrusters at increased temperature reduces propellant requirements. Inasmuch as propellant comprises the bulk of a satellite's mass, even a small percentage reduction makes possible a significant enhancement of the mission in terms of increased payload. Because of its excellent high temperature strength, rhenium is often the structural material of choice. It can be fabricated into free-standing shapes by chemical vapor deposition (CVD) onto an expendable mandrel. What rhenium lacks is oxidation resistance, but this can be provided by a coating of iridium, also by CVD. This paper describes the process used by Ultramet to fabricate 22-N (5-lbf) and, more recently, 445-N (100-lbf) Ir/Re thrusters; characterizes the CVD-deposited materials; and summarizes the materials effects of firing these thrusters. Optimal propellant mixture ratios can be employed because the materials withstand an oxidizing environment up to the melting temperature of iridium, 2400 C (4350 F).

  4. Iridium-coated rhenium thrusters by CVD

    NASA Technical Reports Server (NTRS)

    Harding, John T.; Kazaroff, John M.; Appel, Marshall A.

    1988-01-01

    Operation of spacecraft thrusters at increased temperature reduces propellant requirements. Inasmuch as propellant comprises the bulk of a satellite's mass, even a small percentage reduction makes possible a significant enhancement of the mission in terms of increased payload. Because of its excellent high temperature strength, rhenium is often the structural material of choice. It can be fabricated into free-standing shapes by chemical vapor deposition (CVD) onto an expendable mandrel. What rhenium lacks is oxidation resistance, but this can be provided by a coating of iridium, also by CVD. This paper describes the process used by Ultramet to fabricate 22-N (5-lbf) and, more recently, 445-N (100-lbf) Ir/Re thrusters; characterizes the CVD-deposited materials; and summarizes the materials effects of firing these thrusters. Optimal propellant mixture ratios can be employed because the materials withstand an oxidizing environment up to the meltimg temperature of iridium, 2400 C (4350 F).

  5. Iridium-coated rhenium thrusters by CVD

    NASA Technical Reports Server (NTRS)

    Harding, J. T.; Kazaroff, J. M.; Appel, M. A.

    1989-01-01

    Operation of spacecraft thrusters at increased temperature reduces propellant requirements. Inasmuch as propellant comprises the bulk of a satellite's mass, even a small percentage reduction makes possible a significant enhancement of the mission in terms of increased payload. Because of its excellent high temperature strength, rhenium is often the structural material of choice. It can be fabricated into free-standing shapes by chemical vapor deposition (CVD) onto an expendable mandrel. What rhenium lacks is oxidation resistance, but this can be provided by a coating of iridium, also by CVD. This paper describes the process used by Ultramet to fabricate 22-N (5-lbf) and, more recently, 445-N (100-lbf) Ir/Re thrusters; characterizes the CVD-deposited materials; and summarizes the materials effects of firing these thrusters. Optimal propellant mixture ratios can be employed because the materials withstand an oxidizing environment up to the melting temperature of iridium, 2400 C (4350 F).

  6. Development of Improved Rhenium Coatings for Fluorine Engine Thrust Chambers. [hydrazine-fluorine rocket engines

    NASA Technical Reports Server (NTRS)

    Barton, K. J.; Yurkewycz, R.; Harada, Y.; Daniels, I.

    1981-01-01

    Coating trials were undertaken to evaluate the application of rhenium to carbon-carbon composite sheet by plasma spraying. Optimum spray parameters and coating thickness were identified for production of coatings free from continuous defects and with adequate adherence to the substrate. A tungsten underlayer was not beneficial and possibly detracted from coating integrity. Stress calculations indicated that the proposed operating cycle of the rocket engine would not cause spalling of the rhenium coating. Calculations indicated that permeation of gases through the coating would not be significant during the expected life of the thrust chamber. The feasibility of applying rhenium coatings by laser melting was also studied. Poor wetting of the composite surface by the liquid rhenium precluded production of uniform coatings. Borate/carborate fluxes did not improve wetting characteristics.

  7. Evaluation of oxide-coated iridium-rhenium chambers

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.

    1994-01-01

    Iridium-coated rhenium (Ir-Re) provides long life operation of radiation-cooled rockets at temperatures up to 2200 C. Ceramic oxide coatings could be used to increase Ir-Re rocket lifetimes and allow operation in highly oxidizing environments. Ceramic oxide coatings promise to serve as both thermal and diffusion barriers for the iridium layer. Seven ceramic oxide-coated Ir-Re, 22-N rocket chambers were tested with gaseous hydrogen/gaseous oxygen (GHz/G02) propellants. Five chambers had thick (over 10 mils), monolithic coatings of either hafnia (HfO2) or zirconia (ZrO2). Two chambers had coatings with thicknesses less than 5 mils. One of these chambers had a thin-walled coating of ZrO2 infiltrated with sol gel HfO2. The other chamber had a coating composed of an Ir-oxide composite. The purpose of this test program was to assess the ability of the oxide coatings to withstand the thermal shock of combustion initiation, adhere under repeated thermal cycling, and operate in aggressively oxidizing environments. All of the coatings survived the thermal shock of combustion and demonstrated operation at mixture ratios up to 11. Testing the Ir-oxide composite-coated chamber included over 29 min at mixture ratio 16. The thicker walled coatings provided the larger temperature drops across the oxide layer (up to 570 C), but were susceptible to macrocracking and eventual chipping at a stress concentrator. The cracks apparently resealed during firing, under compression of the oxide layer. The thinner walled coatings did not experience the macrocracking and chipping of the chambers that was seen with the thick, monolithic coatings. However, burn-throughs in the throat region did occur in both of the thin-walled chambers at mixture ratios well above stoichiometric. The burn-throughs were probably the result of oxygen diffusion through the oxide coating that allowed the underlying Ir and Re layers to be oxidized. The results of this test program indicated that the thin-walled oxide

  8. Iridium-Coated Rhenium Radiation-Cooled Rockets

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.; Biaglow, James A.; Schneider, Steven J.

    1997-01-01

    Radiation-cooled rockets are used for a range of low-thrust propulsion functions, including apogee insertion, attitude control, and repositioning of satellites, reaction control of launch vehicles, and primary propulsion for planetary space- craft. The key to high performance and long lifetimes for radiation-cooled rockets is the chamber temperature capability. The material system that is currently used for radiation-cooled rockets, a niobium alloy (C103) with a fused silica coating, has a maximum operating temperature of 1370 C. Temperature limitations of C103 rockets force the use of fuel film cooling, which degrades rocket performance and, in some cases, imposes a plume contamination issue from unburned fuel. A material system composed of a rhenium (Re) substrate and an iridium (Ir) coating has demonstrated operation at high temperatures (2200 C) and for long lifetimes (hours). The added thermal margin afforded by iridium-coated rhenium (Ir/Re) allows reduction or elimination of fuel film cooling. This, in turn, leads to higher performance and cleaner spacecraft environments. There are ongoing government- and industry-sponsored efforts to develop flight Ir/ Re engines, with the primary focus on 440-N, apogee insertion engines. Complementing these Ir/Re engine development efforts is a program to address specific concerns and fundamental characterization of the Ir/Re material system, including (1) development of Ir/Re rocket fabrication methods, (2) establishment of critical Re mechanical properly data, (3) development of reliable joining methods, and (4) characterization of Ir/Re life-limiting mechanisms.

  9. Diffusion aluminide coatings for internal surface of rhenium- and rhenium-ruthenium-containing single-crystal superalloys turbine blades: Part I

    NASA Astrophysics Data System (ADS)

    Mubovadzhyan, S. A.; Galoyan, A. G.

    2012-09-01

    Process of formation rhenium or refractory carbides based diffusion barrier layer (coating) on internal surface of rhenium- and rhenium-ruthenium-containing single-crystal high-temperature alloys (superalloy) turbine blades, prior to diffusion aluminide coating deposition, is studied. It is shown that diffusion barrier layer is preventing deleterious secondary reaction zone formation under aluminide coating during long-term high-temperature operation. The kinetics of powder carburizing process of rhenium- and rhenium-ruthenium-containing high-temperature alloys is investigated, and conditions for carburizing these alloys are determined. The phase composition of the surface layer after carburizing is studied, and the effect of the fractional composition of a carbon-based powder mixture on the carburizing rate is determined.

  10. Testing and evaluation of oxide-coated iridium/rhenium chambers

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.

    1993-01-01

    Iridium-coated rhenium provides long life operation of radiation-cooled rockets at temperatures up to 2200 C. Ceramic oxide coatings could be used to increase iridium/rhenium rocket lifetimes and allow operation in highly oxidizing environments. Ceramic oxide coatings promise to serve as both thermal and diffusion barriers for the iridium layer. Seven ceramic oxide-coated iridium/rhenium, 22 N rocket chambers were tested on gaseous hydrogen/gaseous oxygen propellants. Five chambers had thick (over 10 mils), monolithic coatings of either hafnia or zirconia. Two chambers had coatings with thicknesses less than 5 mils. One of these chambers had a thin-walled coating of zirconia infiltrated with sol gel hafnia. The other chamber had a coating composed of an iridium/oxide composite. The purpose of this test program was to assess the ability of the oxide coatings to withstand the thermal shock of combustion initiation, adhere under repeated thermal cycling, and operate in aggressively oxidizing environments. All of the coatings survived the thermal shock of combustion and demonstrated operation at mixture ratios up to 11. The iridium/oxide composite coated chamber included testing for over 29 minutes at mixture ratio 16. The thicker-walled coatings provided the larger temperature drops across the oxide layer (up to 570 C), but were susceptible to macrocracking and eventual chipping at a stress concentrator. The cracks apparently resealed during firing, under compression of the oxide layer. The thinner-walled coatings did not experience the macrocracking and chipping of the chambers seen with the thick, monolithic coatings. However, burnthroughs in the throat region did occur in both of the thin-walled chambers at mixture ratios well above stochiometric. The burn-throughs were probably the result of oxygen-diffusion through the oxide coating that allowed the underlying iridium and rhenium layers to be oxidized. The results of this test program indicated that the thin

  11. Testing and evaluation of oxide-coated iridium/rhenium chambers

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.

    1993-01-01

    Iridium-coated rhenium provides long life operation of radiation-cooled rockets at temperatures up to 2200 C. Ceramic oxide coatings could be used to increase iridium/rhenium rocket lifetimes and allow operation in highly oxidizing environments. Ceramic oxide coatings promise to serve as both thermal and diffusion barriers for the iridium layer. Seven ceramic oxide-coated iridium/rhenium, 22 N rocket chambers were tested on gaseous hydrogen/gaseous oxygen propellants. Five chambers had thick (over 10 mils), monolithic coatings of either hafnia or zirconia. Two chambers had coatings with thicknesses less than 5 mils. One of these chambers had a thin-walled coating of zirconia infiltrated with sol gel hafnia. The other chamber had a coating composed of an iridium/oxide composite. The purpose of this test program was to assess the ability of the oxide coatings to withstand the thermal shock of combustion initiation, adhere under repeated thermal cycling, and operate in aggressively oxidizing environments. All of the coatings survived the thermal shock of combustion and demonstrated operation at mixture ratios up to 11. The iridium/oxide composite coated chamber included testing for over 29 minutes at mixture ratio 16. The thicker-walled coatings provided the larger temperature drops across the oxide layer (up to 570 C), but were susceptible to macrocracking and eventual chipping at a stress concentrator. The cracks apparently resealed during firing, under compression of the oxide layer. The thinner-walled coatings did not experience the macrocracking and chipping of the chambers seen with the thick, monolithic coatings. However, burnthroughs in the throat region did occur in both of the thin-walled chambers at mixture ratios well above stochiometric. The burn-throughs were probably the result of oxygen-diffusion through the oxide coating that allowed the underlying iridium and rhenium layers to be oxidized. The results of this test program indicated that the thin

  12. Rhenium-coated glass beads for intracolonic administration attenuate TNBS-induced colitis in mice: Proof-of-Concept Study.

    PubMed

    Siczek, Krzysztof; Zatorski, Hubert; Pawlak, Wojciech; Fichna, Jakub

    2015-01-01

    In search for novel effective treatments in inflammatory bowel diseases, a new strategy employing glass beads coated with rhenium nanolayer has been developed and validated in the mouse model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis. Briefly, mice were randomly divided into 5 experimental groups: control (vehicle alone, Group 1); control treated with rhenium-coated glass beads (Group 2); TNBS (Group 3); TNBS treated with rhenium-coated glass beads (Group 4); and TNBS treated with uncoated glass beads (Group 5). Mice from Group 2, 4 and 5 were treated with respective beads (once daily, 5 beads / animal, i.c.) between D3-D6 post-TNBS/vehicle and evaluation of colonic damage was performed on D7, based on macroscopic scoring and clinical parameters. Severe colonic inflammation developed in post-TNBS mice (Group 3) [P <0.001 vs. control (Group 1) for macroscopic score], which was significantly attenuated by treatment with rhenium-coated glass beads (Group 4) [P <0.01 vs. TNBS (Group 3), for macroscopic score]. Neither rhenium-coated glass beads had any effect in control animals (Group 2), nor uncoated glass beads influenced TNBS-induced colitis (Group 5). In conclusion, a novel and attractive strategy for the treatment of colonic inflammation has been proposed; therapy with rhenium-coated glass beads already proved effective in the mouse model of TNBS-induced colitis, now requires further characterization in clinical conditions.

  13. Design, analysis, and fabrication of oxide-coated iridium/rhenium combustion chambers

    NASA Technical Reports Server (NTRS)

    Jang, Q.; Tuffias, R. H.; Laferla, R.; Ghoniem, N. M.

    1993-01-01

    Iridium-coated rhenium (Ir/Re) combustion chambers provide high temperature, oxidation-resistant operation for radiation-cooled liquid-fueled rocket engines. A 22-N (5-lb(sub f)) chamber has been operated for 15 hours at 2200 C (4000 F) using nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) propellant, with negligible internal erosion. The oxidation resistance of these chambers could be further increased by the addition of refractory oxide coatings, providing longer life and/or operation in more oxidizing and higher temperature environments. The oxide coatings would serve as a thermal and diffusion barrier for the iridium coating, lowering the temperature of the iridium layer while also preventing the ingress of oxygen and egress of iridium oxides. This would serve to slow the failure mechanisms of Ir/Re chambers, namely the diffusion of rhenium to the inner surface and the oxidation of iridium. Such protection could extend chamber lifetimes by tens or perhaps hundreds of hours, and allow chamber operation on stoichiometric or higher mixture ratio oxygen/hydrogen (O2/H2) propellant. Extensive thermomechanical, thermochemical, and mass transport modeling was performed as a key material/structure design tool. Based on the results of these analyses, several 22-N oxide-coated Ir/Re chambers were fabricated and delivered to NASA Lewis Research Center for hot-fire testing.

  14. Design, analysis, and fabrication of oxide-coated iridium/rhenium combustion chambers

    NASA Technical Reports Server (NTRS)

    Jang, Q.; Tuffias, R. H.; Laferla, R.; Ghoniem, N. M.

    1993-01-01

    Iridium-coated rhenium (Ir/Re) combustion chambers provide high temperature, oxidation-resistant operation for radiation-cooled liquid-fueled rocket engines. A 22-N (5-lb(sub f)) chamber has been operated for 15 hours at 2200 C (4000 F) using nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) propellant, with negligible internal erosion. The oxidation resistance of these chambers could be further increased by the addition of refractory oxide coatings, providing longer life and/or operation in more oxidizing and higher temperature environments. The oxide coatings would serve as a thermal and diffusion barrier for the iridium coating, lowering the temperature of the iridium layer while also preventing the ingress of oxygen and egress of iridium oxides. This would serve to slow the failure mechanisms of Ir/Re chambers, namely the diffusion of rhenium to the inner surface and the oxidation of iridium. Such protection could extend chamber lifetimes by tens or perhaps hundreds of hours, and allow chamber operation on stoichiometric or higher mixture ratio oxygen/hydrogen (O2/H2) propellant. Extensive thermomechanical, thermochemical, and mass transport modeling was performed as a key material/structure design tool. Based on the results of these analyses, several 22-N oxide-coated Ir/Re chambers were fabricated and delivered to NASA Lewis Research Center for hot-fire testing.

  15. Design, analysis, and fabrication of oxide-coated iridium/rhenium combustion chambers

    NASA Astrophysics Data System (ADS)

    Jang, Q.; Tuffias, R. H.; Laferla, R.; Ghoniem, N. M.

    1993-11-01

    Iridium-coated rhenium (Ir/Re) combustion chambers provide high temperature, oxidation-resistant operation for radiation-cooled liquid-fueled rocket engines. A 22-N (5-lb(sub f)) chamber has been operated for 15 hours at 2200 C (4000 F) using nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) propellant, with negligible internal erosion. The oxidation resistance of these chambers could be further increased by the addition of refractory oxide coatings, providing longer life and/or operation in more oxidizing and higher temperature environments. The oxide coatings would serve as a thermal and diffusion barrier for the iridium coating, lowering the temperature of the iridium layer while also preventing the ingress of oxygen and egress of iridium oxides. This would serve to slow the failure mechanisms of Ir/Re chambers, namely the diffusion of rhenium to the inner surface and the oxidation of iridium. Such protection could extend chamber lifetimes by tens or perhaps hundreds of hours, and allow chamber operation on stoichiometric or higher mixture ratio oxygen/hydrogen (O2/H2) propellant. Extensive thermomechanical, thermochemical, and mass transport modeling was performed as a key material/structure design tool. Based on the results of these analyses, several 22-N oxide-coated Ir/Re chambers were fabricated and delivered to NASA Lewis Research Center for hot-fire testing.

  16. Long Life Testing of Oxide-Coated Iridium/Rhenium Rockets

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.

    1995-01-01

    22-N class rockets, composed of a rhenium (Re) substrate, an iridium (Ir) coating, and an additional composite coating consisting of Ir and a ceramic oxide, were tested on gaseous oxygen/gaseous hydrogen (GO2/GH2) propellants. Two rockets were tested, one for nearly 39 hours at a nominal mixture ratio (MR) of 4.6 and chamber pressure (Pc) of 469 kPa, and the other for over 13 hours at a nominal MR of 5.8 and 621 kPa Pc. Four additional Ir/Re rockets, with a composite Ir-oxide coating fabricated using a modified process, were also tested, including one for 1.3 hours at a nominal MR of 16.7 and Pc of 503 kPa. The long lifetimes demonstrated on low MR GO2/GH2 suggest greatly extended chamber lifetimes (tens of hours) in the relatively low oxidizing combustion environments of Earth storable propellants. The oxide coatings could also serve as a protective coating in the near injector region, where a still-mixing flowfield may cause degradation of the Ir layer. Operation at MR close to 17 suggests that oxide-coated Ir/Re rockets could be used in severely oxidizing combustion environments, such as high MR GO2/GH2, oxygen/hydrocarbon, and liquid gun propellants.

  17. Characterization of Iridium Coated Rhenium Used in High-Temperature, Radiation-Cooled Rocket Thrusters

    NASA Technical Reports Server (NTRS)

    Stulen, R. H.; Boehme, D. R.; Clift, W. M.; McCarty, K. F.

    1990-01-01

    Materials used for radiation-cooled rocket thrusters must be capable of surviving under extreme conditions of high-temperatures and oxidizing environments. While combustion efficiency is optimized at high temperatures, many refractory metals are unsuitable for thruster applications due to rapid material loss from the formation of volatile oxides. This process occurs during thruster operation by reaction of the combustion products with the material surface. Aerojet Technical Systems has developed a thruster cone chamber constructed of Re coated with Ir on the inside surface where exposure to the rocket exhaust occurs. Re maintains its structural integrity at high temperature and the Ir coating is applied as an oxidation barrier. Ir also forms volatile oxide species (IrO2 and IrO3) but at a considerably slower rate than Re. In order to understand the performance limits of Ir-coated Re thrusters, we are investigating the interdiffusion and oxidation kinetics of Ir/Re. The formation of iridium and rhenium oxides has been monitored in situ by Raman spectroscopy during high temperature exposure to oxygen. For pure Ir, the growth of oxide films as thin as approximately 200 A could be easily detected and the formation of IrO2 was observed at temperatures as low as 600 C. Ir/Re diffusion test specimens were prepared by magnetron sputtering of Ir on Re substrates. Concentration profiles were determined by sputter Auger depth profiles of the heat treated specimens. Significant interdiffusion was observed at temperatures as low as 1000 C. Measurements of the activation energy suggest that below 1350 C, the dominant diffusion path is along defects, most likely grain boundaries, rather than bulk diffusion through the grains. The phases that form during interdiffusion have been examined by x ray diffraction. Analysis of heated test specimens indicates that the Ir-Re reaction produces a solid solution phase of Ir dissolved in the HCP structure of Re.

  18. Diffusion aluminide coatings for protecting the surface of the internal space of single-crystal turbine blades made of rhenium- and rhenium-ruthenium-containing high-temperature alloys: Part II

    NASA Astrophysics Data System (ADS)

    Muboyadzhyan, S. A.; Galoyan, A. G.

    2013-03-01

    The production of heat-resistant aluminide and chromium aluminide protective coatings with a barrier layer, which is based on the carbides of the refractory elements of a nickel superalloy, is considered for the powder methods of diffusion chromium and aluminum saturation of the surface of the internal space of single-crystal high-pressure turbine blades made of high-temperature rhenium- and rhenium-ruthenium-containing alloys for a gas turbine engine. The barrier layer is shown to prevent the formation of a secondary reaction zone, which softens an alloy, under a heat-resistant coating during long-term high-temperature holding. The kinetics of powder-assisted aluminizing and chromizing-aluminizing of high-temperature rhenium- and rhenium-ruthenium-containing alloys is studied, aluminizing and chromizing-aluminizing conditions are determined, and the effect of heat-resistant diffusion coatings with a barrier layer on the mechanical properties of the high-temperature alloys is investigated.

  19. Serpentine metal gasket

    DOEpatents

    Rothgeb, Timothy Moore [Norfolk, VA; Reece, Charles Edwin [Yorktown, VA

    2009-06-02

    A metallic seal or gasket for use in the joining of cryogenic fluid conduits, the seal or gasket having a generally planar and serpentine periphery defining a central aperture. According to a preferred embodiment, the periphery has at least two opposing elongated serpentine sides and two opposing arcuate ends joining the opposing elongated serpentine sides and is of a hexagonal cross-section.

  20. Liquid-Oxygen-Compatible Cement for Gaskets

    NASA Technical Reports Server (NTRS)

    Elmore, N. L.; Neale, B. C.

    1984-01-01

    Fluorelastomer and metal bonded reliably by new procedure. To cure fluoroelastomer cement, metal plate/gasket assembly placed in vacuum bag evacuated to minimum vacuum of 27 inches (69 cm) of mercury. Vacuum maintained throughout heating process and until assembly returns to ambient room temperature. Used to seal gaskets and O-rings or used to splice layers of elastomer to form non-standard sized O-rings. Another possible use is to apply protective, liquid-oxygen-compatible coating to metal parts.

  1. Rhenium Redefined

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Through a Small Business Innovation Research (SBIR) contract with NASA's Glenn Research Center, Rhenium Alloys, Inc., of Elyria, Ohio, developed a new method for producing rhenium combustion chambers. Using room temperature isostatic pressing, Rhenium Alloys, Inc., compacted rhenium powder to a high density and into the approximated end shape and dimension of the rocket thruster. The item was then subjected to sintering and containerless hot isostatic pressing, increasing the density of the powder metallurgy part. With the new manufacturing process, both production time and costs are reduced while quality is significantly increased. The method enabled the company to deliver two chemical rocket thrusters to Glenn Research Center. The company makes rhenium a practical choice in manufacturing fields, including the aerospace, nuclear, and electronic industries, with upcoming opportunities projected in medical instrumentation.

  2. Gasket with pushrod retainer

    DOEpatents

    Knudsen, Julian R.; Welch, Christopher B.

    2005-04-26

    In an engine having a rocker member adapted to rock about an axis intermediate the rocker member and a pushrod extending from a lower body to an upper body and engaging an end of the rocker member, a gasket for sealing the lower body to the upper body is provided. The gasket includes a sealing portion adapted to substantially seal at least a portion of the upper body to the lower body, and a pushrod support portion extending outwardly from the sealing portion adapted to engage the pushrod. At least a portion of the pushrod support portion engaging the pushrod is constructed from a material that is softer than the material of the pushrod.

  3. Rhenium Rocket Manufacturing Technology

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The NASA Lewis Research Center's On-Board Propulsion Branch has a research and technology program to develop high-temperature (2200 C), iridium-coated rhenium rocket chamber materials for radiation-cooled rockets in satellite propulsion systems. Although successful material demonstrations have gained much industry interest, acceptance of the technology has been hindered by a lack of demonstrated joining technologies and a sparse materials property data base. To alleviate these concerns, we fabricated rhenium to C-103 alloy joints by three methods: explosive bonding, diffusion bonding, and brazing. The joints were tested by simulating their incorporation into a structure by welding and by simulating high-temperature operation. Test results show that the shear strength of the joints degrades with welding and elevated temperature operation but that it is adequate for the application. Rhenium is known to form brittle intermetallics with a number of elements, and this phenomena is suspected to cause the strength degradation. Further bonding tests with a tantalum diffusion barrier between the rhenium and C-103 is planned to prevent the formation of brittle intermetallics.

  4. Diffusion mechanisms in chemical vapor-deposited iridium coated on chemical vapor-deposited rhenium

    NASA Technical Reports Server (NTRS)

    Hamilton, J. C.; Yang, N. Y. C.; Clift, W. M.; Boehme, D. R.; Mccarty, K. F.; Franklin, J. E.

    1992-01-01

    Radiation-cooled rocket thruster chambers have been developed which use CVD Re coated with CVD Ir on the interior surface that is exposed to hot combustion gases. The Ir serves as an oxidation barrier which protects the structural integrity-maintaining Re at elevated temperatures. The diffusion kinetics of CVD materials at elevated temperatures is presently studied with a view to the prediction and extension of these thrusters' performance limits. Line scans for Ir and Re were fit on the basis of a diffusion model, in order to extract relevant diffusion constants; the fastest diffusion process is grain-boundary diffusion, where Re diffuses down grain boundaries in the Ir overlayer.

  5. Diffusion mechanisms in chemical vapor-deposited iridium coated on chemical vapor-deposited rhenium

    NASA Technical Reports Server (NTRS)

    Hamilton, J. C.; Yang, N. Y. C.; Clift, W. M.; Boehme, D. R.; Mccarty, K. F.; Franklin, J. E.

    1992-01-01

    Radiation-cooled rocket thruster chambers have been developed which use CVD Re coated with CVD Ir on the interior surface that is exposed to hot combustion gases. The Ir serves as an oxidation barrier which protects the structural integrity-maintaining Re at elevated temperatures. The diffusion kinetics of CVD materials at elevated temperatures is presently studied with a view to the prediction and extension of these thrusters' performance limits. Line scans for Ir and Re were fit on the basis of a diffusion model, in order to extract relevant diffusion constants; the fastest diffusion process is grain-boundary diffusion, where Re diffuses down grain boundaries in the Ir overlayer.

  6. Filter holder and gasket assembly for candle or tube filters

    DOEpatents

    Lippert, Thomas Edwin; Alvin, Mary Anne; Bruck, Gerald Joseph; Smeltzer, Eugene E.

    1999-03-02

    A filter holder and gasket assembly for holding a candle filter element within a hot gas cleanup system pressure vessel. The filter holder and gasket assembly includes a filter housing, an annular spacer ring securely attached within the filter housing, a gasket sock, a top gasket, a middle gasket and a cast nut.

  7. Filter holder and gasket assembly for candle or tube filters

    DOEpatents

    Lippert, T.E.; Alvin, M.A.; Bruck, G.J.; Smeltzer, E.E.

    1999-03-02

    A filter holder and gasket assembly are disclosed for holding a candle filter element within a hot gas cleanup system pressure vessel. The filter holder and gasket assembly includes a filter housing, an annular spacer ring securely attached within the filter housing, a gasket sock, a top gasket, a middle gasket and a cast nut. 9 figs.

  8. Gaskets for low-energy houses

    SciTech Connect

    Harr, D.

    1986-05-01

    New materials and techniques make it easier to build today's tight, energy-efficient homes. One system that has won many converts recently is the airtight drywall approach (ADA). ADA relies heavily on the use of foam gasketing. In the ADA building system, nearly all joints--sill to foundation, band joist, wall plate to subfloor, and drywall to frame-are gasketed with foam tapes. The combination of gaskets, drywall, and caulk creates an airtight envelope. Foam gasketing tape is well suited from many of these joints because it is clean, economical, and easy to apply. The right gasket will maintain the seal even if the joint moves, and won't squeeze out of the joint under compression. Caulk, on the other hand, is messy, hard to apply, and squeezes out of the joint under compression. Saturated urethanes are elastic sealants that always recover, even after being completely compressed. Some saturated urethanes recover faster than others, depending on what saturant is used, but all exert a force to recover because they are urethanes. In the construction industry, where gaskets are likely to be buried permanently within the framework, saturated urethane foam gaskets really make sense.

  9. Manifold gasket accommodating differential movement of fuel cell stack

    DOEpatents

    Kelley, Dana A.; Farooque, Mohammad

    2007-11-13

    A gasket for use in a fuel cell system having at least one externally manifolded fuel cell stack, for sealing the manifold edge and the stack face. In accordance with the present invention, the gasket accommodates differential movement between the stack and manifold by promoting slippage at interfaces between the gasket and the dielectric and between the gasket and the stack face.

  10. Fiber gasket and method of making same

    DOEpatents

    Bruck, Gerald Joseph; Alvin, Mary Anne; Smeltzer, Eugene E.

    2003-01-01

    A gasket (1) is made by repetitively spirally winding a fiber (3) back on itself in a closed path. The gasket (1) so made has a multi-layer spiral winding (1) formed in a loop (5). The fiber (3) can be wound at a constant wrap rate to form a gasket with a uniform cross-section around the loop. Alternatively, the wrap rate can be varied, increased to increase cross-sectional bulk, and decreased to reduce cross-section bulk around the loop (5). Also, the spiral winding (7) can be applied over a core (13) of either strands of the fiber (3) or a dissimilar material providing a desired property such as resiliency, stiffness or others. For high temperature applications, a ceramic fiber (3) can be used. The gasket (1) can have any of various geometric configurations with or without a core (13).

  11. Rhenium material properties

    NASA Technical Reports Server (NTRS)

    Biaglow, James A.

    1995-01-01

    Tensile data were obtained from four different types of rhenium at ambient and elevated temperatures. The four types of rhenium included chemical vapor deposition (CVD) and three powder metallurgy (PM) types, i.e., rolled sheet and pressed and sintered bars, with and without hot isostatic pressure (HIP) treatment. Results revealed a wide range of values with ultimate strengths at ambient temperatures varying from 663 MPa for CVD rhenium to 943 MPa for rolled sheet. A similar spread was also obtained for material tested at 1088 K and 1644 K. The wide variance observed with the different materials indicated that the rhenium manufacturing process, material composition and prior handling strongly dictated its properties. In addition to tensile properties, CVD, pressed and sintered material and HIP rhenium successfully completed 100 cycles of low cycle fatigue. Creep data were also obtained showing that CVD and pressed and sintered rhenium could sustain five hours of testing under a tension of 27.5 MPa at 1922 K.

  12. Rhenium material properties

    SciTech Connect

    Biaglow, J.A.

    1995-09-01

    Tensile data were obtained from four different types of rhenium at ambient and elevated temperatures. The four types of rhenium included chemical vapor deposition (CVD) and three powder metallurgy (PM) types, i.e., rolled sheet and pressed and sintered bars, with and without hot isostatic pressure (HIP) treatment. Results revealed a wide range of values with ultimate strengths at ambient temperatures varying from 663 MPa for CVD rhenium to 943 MPa for rolled sheet. A similar spread was also obtained for material tested at 1088 K and 1644 K. The wide variance observed with the different materials indicated that the rhenium manufacturing process, material composition and prior handling strongly dictated its properties. In addition to tensile properties, CVD, pressed and sintered material and HIP rhenium successfully completed 100 cycles of low cycle fatigue. Creep data were also obtained showing that CVD and pressed and sintered rhenium could sustain five hours of testing under a tension of 27.5 MPa at 1922 K.

  13. Rhenium-Foil Witness Cylinders

    NASA Technical Reports Server (NTRS)

    Knight, B. L.

    1992-01-01

    Cylindrical portion of wall of combustion chamber replaced with rhenium foil mounted on holder. Rhenium oxidizes without melting, indicating regions of excess oxidizer in combustion-chamber flow. Rhenium witness foils also useful in detecting excess oxygen and other oxidizers at temperatures between 2,000 and 3,600 degrees F in burner cores of advanced gas-turbine engines.

  14. Rhenium-Foil Witness Cylinders

    NASA Technical Reports Server (NTRS)

    Knight, B. L.

    1992-01-01

    Cylindrical portion of wall of combustion chamber replaced with rhenium foil mounted on holder. Rhenium oxidizes without melting, indicating regions of excess oxidizer in combustion-chamber flow. Rhenium witness foils also useful in detecting excess oxygen and other oxidizers at temperatures between 2,000 and 3,600 degrees F in burner cores of advanced gas-turbine engines.

  15. Manufacturing SP-100 rhenium tubes

    NASA Astrophysics Data System (ADS)

    Sayre, Edwin D.; Ruffo, Thomas J.

    1992-01-01

    A process for producing high quality, thin walled, wrought, rhenium tubing was successfully developed and qualified in the SP-100 fuel fabrication program. Rhenium was selected for the fuel-cladding barrier versus tungsten because of the cold workability and nuclear characteristics of rhenium. Several tube fabricating processes including swaging, drawing, and extruding sintered tube shells and chemical vapor deposition were evaluated before a drawn tube made by forming and electron beam welding rhenium strip was selected as the most cost effective. The process for making the rhenium tubes is discussed in general and the tube, room temperature, tensile properties are compared favorably with the properties reported in the literature.

  16. 46 CFR 98.30-8 - Gaskets and lining.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Gaskets and lining. 98.30-8 Section 98.30-8 Shipping... Gaskets and lining. No person may transfer a hazardous material to or from a portable tank on board a vessel unless each gasket and the lining of the portable tank are made of a material that is—...

  17. 46 CFR 64.23 - Gasket and lining.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Gasket and lining. 64.23 Section 64.23 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.23 Gasket and lining. Each gasket and lining must be made...

  18. Rhenium Mechanical Properties and Joining Technology

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.; Biaglow, James A.

    1996-01-01

    Iridium-coated rhenium (Ir/Re) provides thermal margin for high performance and long life radiation cooled rockets. Two issues that have arisen in the development of flight Ir/Re engines are the sparsity of rhenium (Re) mechanical property data (particularly at high temperatures) required for engineering design, and the inability to directly electron beam weld Re chambers to C103 nozzle skirts. To address these issues, a Re mechanical property database is being established and techniques for creating Re/C103 transition joints are being investigated. This paper discusses the tensile testing results of powder metallurgy Re samples at temperatures from 1370 to 2090 C. Also discussed is the evaluation of Re/C103 transition pieces joined by both, explosive and diffusion bonding. Finally, the evaluation of full size Re transition pieces, joined by inertia welding, as well as explosive and diffusion bonding, is detailed.

  19. 30 CFR 18.27 - Gaskets.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Gaskets. 18.27 Section 18.27 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES Construction and Design Requirements § 18.27...

  20. 30 CFR 18.27 - Gaskets.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Gaskets. 18.27 Section 18.27 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES Construction and Design Requirements § 18.27...

  1. Indium Foil Serves As Thermally Conductive Gasket

    NASA Technical Reports Server (NTRS)

    Eastman, G. Yale; Dussinger, Peter M.

    1993-01-01

    Indium foil found useful as gasket to increase thermal conductance between bodies clamped together. Deforms to fill imperfections on mating surfaces. Used where maximum temperature in joint less than melting temperature of indium. Because of low melting temperature of indium, most useful in cryogenic applications.

  2. 30 CFR 18.27 - Gaskets.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Gaskets. 18.27 Section 18.27 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES Construction and Design Requirements §...

  3. 30 CFR 18.27 - Gaskets.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Gaskets. 18.27 Section 18.27 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES Construction and Design Requirements §...

  4. 30 CFR 18.27 - Gaskets.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Gaskets. 18.27 Section 18.27 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES Construction and Design Requirements §...

  5. Indium Foil Serves As Thermally Conductive Gasket

    NASA Technical Reports Server (NTRS)

    Eastman, G. Yale; Dussinger, Peter M.

    1993-01-01

    Indium foil found useful as gasket to increase thermal conductance between bodies clamped together. Deforms to fill imperfections on mating surfaces. Used where maximum temperature in joint less than melting temperature of indium. Because of low melting temperature of indium, most useful in cryogenic applications.

  6. O-ring gasket test fixture

    NASA Technical Reports Server (NTRS)

    Turner, James Eric (Inventor); Mccluney, Donald Scott (Inventor)

    1991-01-01

    An apparatus is presented for testing O-ring gaskets under a variety of temperature, pressure, and dynamic loading conditions. Specifically, this apparatus has the ability to simulate a dynamic loading condition where the sealing surface in contact with the O-ring moves both away from and axially along the face of the O-ring.

  7. Flexible ceramic gasket for SOFC generator

    DOEpatents

    Zafred, Paolo [Murrysville, PA; Prevish, Thomas [Trafford, PA

    2009-02-03

    A solid oxide fuel cell generator (10) contains stacks of hollow axially elongated fuel cells (36) having an open top end (37), an oxidant inlet plenum (52), a feed fuel plenum (11), a combustion chamber (94) for combusting reacted oxidant/spent fuel; and, optionally, a fuel recirculation chamber (106) below the combustion chamber (94), where the fuel recirculation chamber (94) is in part defined by semi-porous fuel cell positioning gasket (108), all within an outer generator enclosure (8), wherein the fuel cell gasket (108) has a laminate structure comprising at least a compliant fibrous mat support layer and a strong, yet flexible woven layer, which may contain catalytic particles facing the combustion chamber, where the catalyst, if used, is effective to further oxidize exhaust fuel and protect the open top end (37) of the fuel cells.

  8. Gasket and snap ring installation tool

    DOEpatents

    Southerland, Jr., James M.; Barringer, Jr., Curtis N.

    1994-01-01

    A tool for installing a gasket and a snap ring including a shaft, a first plate attached to the forward end of the shaft, a second plate slidably carried by the shaft, a spring disposed about the shaft between the first and second plates, and a sleeve that is free to slide over the shaft and engage the second plate. The first plate has a loading surface with a loading groove for receiving a snap ring and a shoulder for holding a gasket. A plurality of openings are formed through the first plate, communicating with the loading groove and approximately equally spaced about the groove. A plurality of rods are attached to the second plate, each rod slidable in one of the openings. In use, the loaded tool is inserted into a hollow pipe or pipe fitting having an internal flange and an internal seating groove, such that the gasket is positioned against the flange and the ring is in the approximate plane of the seating groove. The sleeve is pushed against the second plate, sliding the second plate towards the first plate, compressing the spring and sliding the rods forwards in the openings. The rods engage the snap ring and urge the ring from the loading groove into the seating groove.

  9. Gasket and snap ring installation tool

    SciTech Connect

    Southerland, J.M. Jr.; Barringer, C.N. Jr.

    1994-09-06

    A tool is disclosed for installing a gasket and a snap ring including a shaft, a first plate attached to the forward end of the shaft, a second plate slidably carried by the shaft, a spring disposed about the shaft between the first and second plates, and a sleeve that is free to slide over the shaft and engage the second plate. The first plate has a loading surface with a loading groove for receiving a snap ring and a shoulder for holding a gasket. A plurality of openings are formed through the first plate, communicating with the loading groove and approximately equally spaced about the groove. A plurality of rods are attached to the second plate, each rod slidable in one of the openings. In use, the loaded tool is inserted into a hollow pipe or pipe fitting having an internal flange and an internal seating groove, such that the gasket is positioned against the flange and the ring is in the approximate plane of the seating groove. The sleeve is pushed against the second plate, sliding the second plate towards the first plate, compressing the spring and sliding the rods forwards in the openings. The rods engage the snap ring and urge the ring from the loading groove into the seating groove. 6 figs.

  10. Gasket Assembly for Sealing Mating Surfaces

    NASA Technical Reports Server (NTRS)

    Bryant, Melvin A., III (Inventor)

    2003-01-01

    A pair of substantially opposed mating surfaces are joined to each other and sealed in place by means of an electrically-conductive member which is placed in proximity to the mating surfaces. The electrically-conductive member has at least one element secured thereto which is positioned to contact the mating surfaces, and which softens when the electrically-conductive member is heated by passing an electric current therethrough. The softened element conforms to the mating surfaces, and upon cooling of the softened element the mating surfaces are joined together in an effective seal. Of particular significance is an embodiment of the electrically-conductive member which is a gasket having an electrically-conductive gasket base and a pair of the elements secured to opposite sides of the gasket base. This embodiment is positioned between the opposed mating surfaces to be joined to each other. Also significant is an embodiment of the electrically-conductive member which is an electrically-conductive sleeve having an element secured to its inner surface. This embodiment surrounds cylindrical members the bases of which are the substantially opposed mating surfaces to be joined, and the element on the inner surface of the sleeve contacts the outer surfaces of the cylindrical members.

  11. Equation of state of rhenium and application for ultra high pressure calibration

    SciTech Connect

    Anzellini, Simone; Dewaele, Agnès; Occelli, Florent; Loubeyre, Paul; Mezouar, Mohamed

    2014-01-28

    The isothermal equation of state of rhenium has been measured by powder X-ray diffraction experiments up to 144 GPa at room temperature in a diamond anvil cell. A helium pressure transmitting medium was used to minimize the non-hydrostatic stress on the sample. The fit of pressure-volume data yields a bulk modulus K{sub 0} = 352.6 GPa and a pressure derivative of the bulk modulus K′{sub 0}=4.56. This equation of state differs significantly from a recent determination [Dubrovinsky et al., Nat. Commun. 3, 1163 (2012)], giving here a lower pressure at a given volume. The possibility of using rhenium gasket X-ray diffraction signal, with the present equation of state, to evaluate multi-Mbar pressures in the chamber of diamond anvil cells is discussed.

  12. Mineral of the month: rhenium

    USGS Publications Warehouse

    Magyar, Michael J.

    2005-01-01

    Rhenium, an exotic, heat-resistant metal, has grown in importance since its discovery nearly 80 years ago. First isolated by a team of German chemists studying a platinum ore, the mineral was named for the Rhine River. From then until the 1960s, only 2 metric tons of rhenium were produced worldwide. In 2004, worldwide production was 40 metric tons.

  13. Long-Term Strength of a Composition of Complex Refractory Coating and Single-Crystal Rhenium-Alloyed Nickel Alloy after High-Temperature Holds

    NASA Astrophysics Data System (ADS)

    Kuznetsov, V. P.; Lesnikov, V. P.; Moroz, E. V.; Khadyev, M. S.; Konakova, I. P.

    2013-11-01

    The long-term strength of a system of single-crystal nickel alloy ZhS36-VI with Cr - Al gas circulation coating (GCC) + Ni - Cr - Al - Ta - Re - Yion-plasma coating (IPC) + Al - Ni - Cr - Yion-plasma coating (IPC) is analyzed under conditions close to the operating ones after a hold for 1 - 1000 h in a temperature range of 1050 - 1300°C.

  14. 46 CFR 56.30-35 - Gasketed mechanical couplings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Gasketed mechanical couplings. 56.30-35 Section 56.30-35 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Selection and Limitations of Piping Joints § 56.30-35 Gasketed mechanical couplings. (a) This...

  15. 46 CFR 56.30-35 - Gasketed mechanical couplings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Gasketed mechanical couplings. 56.30-35 Section 56.30-35 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Selection and Limitations of Piping Joints § 56.30-35 Gasketed mechanical couplings. (a) This...

  16. 46 CFR 56.30-35 - Gasketed mechanical couplings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Gasketed mechanical couplings. 56.30-35 Section 56.30-35 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Selection and Limitations of Piping Joints § 56.30-35 Gasketed mechanical couplings. (a) This...

  17. 46 CFR 56.30-35 - Gasketed mechanical couplings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Gasketed mechanical couplings. 56.30-35 Section 56.30-35 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Selection and Limitations of Piping Joints § 56.30-35 Gasketed mechanical couplings. (a) This...

  18. 46 CFR 56.30-35 - Gasketed mechanical couplings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Gasketed mechanical couplings. 56.30-35 Section 56.30-35 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Selection and Limitations of Piping Joints § 56.30-35 Gasketed mechanical couplings. (a) This...

  19. Spiral-wound gasket forms low-temperature seal

    NASA Technical Reports Server (NTRS)

    Irick, S. C.

    1981-01-01

    Spiral-wound cryogenic gasket with one component requires no encapsulant and is easily produced with self-locking features. Seal either opens and closes or is fixed. It is made by skiving strip from circumference of disk of glass-filled material. Successive turns of strip are spirally wrapped in groove machined into one flange surface. Closing joint compresses gasket.

  20. Partial-Vacuum-Gasketed Electrochemical Corrosion Cell

    NASA Technical Reports Server (NTRS)

    Bonifas, Andrew P.; Calle, Luz M.; Hintze, Paul E.

    2006-01-01

    An electrochemical cell for making corrosion measurements has been designed to prevent or reduce crevice corrosion, which is a common source of error in prior such cells. The present cell (see figure) includes an electrolyte reservoir with O-ring-edged opening at the bottom. In preparation for a test, the reservoir, while empty, is pressed down against a horizontal specimen surface to form an O-ring seal. A purge of air or other suitable gas is begun in the reservoir, and the pressure in the reservoir is regulated to maintain a partial vacuum. While maintaining the purge and partial vacuum, and without opening the interior of the reservoir to the atmosphere, the electrolyte is pumped into the reservoir. The reservoir is then slowly lifted a short distance off the specimen. The level of the partial vacuum is chosen such that the differential pressure is just sufficient to keep the electrolyte from flowing out of the reservoir through the small O-ring/specimen gap. Electrochemical measurements are then made. Because there is no gasket (and, hence, no crevice between the specimen and the gasket), crevice corrosion is unlikely to occur.

  1. Development and Evaluation of High Temperature Gaskets for Hypersonic and Reentry Applications

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay; Shpargel, Tarah

    2007-01-01

    A wide variety of flexible gasket compositions were developed and tested at high temperatures. The gasket material system has high temperature capability. GRABER sealants were very effective in sealing machined ACC-4 composite surfaces. The gasket composition do not bond strongly with the ACC-4 substrate materials. The density of gasket materials can be tailored to show appropriate compressibility.

  2. Oxide strengthened molybdenum-rhenium alloy

    DOEpatents

    Bianco, Robert; Buckman, Jr., R. William

    2000-01-01

    Provided is a method of making an ODS molybdenum-rhenium alloy which includes the steps of: (a) forming a slurry containing molybdenum oxide and a metal salt dispersed in an aqueous medium, the metal salt being selected from nitrates or acetates of lanthanum, cerium or thorium; (b) heating the slurry in the presence of hydrogen to form a molybdenum powder comprising molybdenum and an oxide of the metal salt; (c) mixing rhenium powder with the molybdenum powder to form a molybdenum-rhenium powder; (d) pressing the molybdenum-rhenium powder to form a molybdenum-rhenium compact; (e) sintering the molybdenum-rhenium compact in hydrogen or under a vacuum to form a molybdenum-rhenium ingot; and (f) compacting the molybdenum-rhenium ingot to reduce the cross-sectional area of the molybdenum-rhenium ingot and form a molybdenum-rhenium alloy containing said metal oxide. The present invention also provides an ODS molybdenum-rhenium alloy made by the method. A preferred Mo--Re-ODS alloy contains 7-14 weight % rhenium and 2-4 volume % lanthanum oxide.

  3. Evaluation of Rhenium Joining Methods

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.; Morren, Sybil H.

    1995-01-01

    Coupons of rhenium-to-Cl03 flat plate joints, formed by explosive and diffusion bonding, were evaluated in a series of shear tests. Shear testing was conducted on as-received, thermally-cycled (100 cycles, from 21 to 1100 C), and thermally-aged (3 and 6 hrs at 1100 C) joint coupons. Shear tests were also conducted on joint coupons with rhenium and/or Cl03 electron beam welded tabs to simulate the joint's incorporation into a structure. Ultimate shear strength was used as a figure of merit to assess the effects of the thermal treatment and the electron beam welding of tabs on the joint coupons. All of the coupons survived thermal testing intact and without any visible degradation. Two different lots of as-received, explosively-bonded joint coupons had ultimate shear strengths of 281 and 310 MPa and 162 and 223 MPa, respectively. As-received, diffusion-bonded coupons had ultimate shear strengths of 199 and 348 MPa. For the most part, the thermally-treated and rhenium weld tab coupons had shear strengths slightly reduced or within the range of the as-received values. Coupons with Cl03 weld tabs experienced a significant reduction in shear strength. The degradation of strength appeared to be the result of a poor heat sink provided during the electron beam welding. The Cl03 base material could not dissipate heat as effectively as rhenium, leading to the formation of a brittle rhenium-niobium intermetallic.

  4. REVIEW OF ENERGY EFFICIENCY OF REFRIGERATOR/FREEZER GASKETS

    EPA Science Inventory

    The report gives results of an investigation of the significance of heat leakage through gaskets in household refrigerator/freezers, explores different design features, and suggests further study if necessary. The report gives results of an extensive literature review, interviews...

  5. REVIEW OF ENERGY EFFICIENCY OF REFRIGERATOR/FREEZER GASKETS

    EPA Science Inventory

    The report gives results of an investigation of the significance of heat leakage through gaskets in household refrigerator/freezers, explores different design features, and suggests further study if necessary. The report gives results of an extensive literature review, interviews...

  6. DEVELOPMENT OF REMOTE HANFORD CONNECTOR GASKET REPLACEMENT TOOLING FOR DWPF

    SciTech Connect

    Krementz, D.; Coughlin, Jeffrey

    2009-05-05

    The Defense Waste Processing Facility (DWPF) requested the Savannah River National Laboratory (SRNL) to develop tooling and equipment to remotely replace gaskets in mechanical Hanford connectors to reduce personnel radiation exposure as compared to the current hands-on method. It is also expected that radiation levels will continually increase with future waste streams. The equipment is operated in the Remote Equipment Decontamination Cell (REDC), which is equipped with compressed air, two master-slave manipulators (MSM's) and an electro-mechanical manipulator (EMM) arm for operation of the remote tools. The REDC does not provide access to electrical power, so the equipment must be manually or pneumatically operated. The MSM's have a load limit at full extension of ten pounds, which limited the weight of the installation tool. In order to remotely replace Hanford connector gaskets several operations must be performed remotely, these include: removal of the spent gasket and retaining ring (retaining ring is also called snap ring), loading the new snap ring and gasket into the installation tool and installation of the new gasket into the Hanford connector. SRNL developed and tested tools that successfully perform all of the necessary tasks. Removal of snap rings from horizontal and vertical connectors is performed by separate air actuated retaining ring removal tools and is manipulated in the cell by the MSM. In order install a new gasket, the snap ring loader is used to load a new snap ring into a groove in the gasket installation tool. A new gasket is placed on the installation tool and retained by custom springs. An MSM lifts the installation tool and presses the mounted gasket against the connector block. Once the installation tool is in position, the gasket and snap ring are installed onto the connector by pneumatic actuation. All of the tools are located on a custom work table with a pneumatic valve station that directs compressed air to the desired tool and

  7. Oxide strengthened molybdenum-rhenium alloy

    SciTech Connect

    Bianco, Robert; Buckman, William R. Jr.

    1998-12-01

    Provided is a method of making an ODS molybdenum-rhenium alloy which includes the steps of: (1) forming a slurry containing molybdenum oxide and a metal salt dispersed in an aqueous medium, the metal salt being selected from nitrates or acetates of lanthanum, cerium or thorium; (2) heating the slurry in the presence of hydrogen to form a molybdenum powder comprising molybdenum and an oxide of the metal salt; (3) mixing rhenium powder with the molybdenum powder to form a molybdenum-rhenium powder; (4) pressing the molybdenum-rhenium powder to form a molybdenum-rhenium compact; (5) sintering the molybdenum-rhenium compact in hydrogen or under a vacuum to form a molybdenum-rhenium ingot; and (6) compacting the molybdenum-rhenium ingot to reduce the cross-sectional area of the molybdenum-rhenium ingot and form a molybdenum-rhenium alloy containing said metal oxide. The present invention also provides an ODS molybdenum-rhenium alloy made by the method.

  8. Embedded Strain Gauges for Condition Monitoring of Silicone Gaskets

    PubMed Central

    Schotzko, Timo; Lang, Walter

    2014-01-01

    A miniaturized strain gauge with a thickness of 5 µm is molded into a silicone O-ring. This is a first step toward embedding sensors in gaskets for structural health monitoring. The signal of the integrated sensor exhibits a linear correlation with the contact pressure of the O-ring. This affords the opportunity to monitor the gasket condition during installation. Thus, damages caused by faulty assembly can be detected instantly, and early failures, with their associated consequences, can be prevented. Through the embedded strain gauge, the contact pressure applied to the gasket can be directly measured. Excessive pressure and incorrect positioning of the gasket can cause structural damage to the material of the gasket, which can lead to an early outage. A platinum strain gauge is fabricated on a thin polyimide layer and is contacted through gold connections. The measured resistance pressure response exhibits hysteresis for the first few strain cycles, followed by a linear behavior. The short-term impact of the embedded sensor on the stability of the gasket is investigated. Pull-tests with O-rings and test specimens have indicated that the integration of the miniaturized sensors has no negative impact on the stability in the short term. PMID:25014099

  9. Embedded strain gauges for condition monitoring of silicone gaskets.

    PubMed

    Schotzko, Timo; Lang, Walter

    2014-07-10

    A miniaturized strain gauge with a thickness of 5 µm is molded into a silicone O-ring. This is a first step toward embedding sensors in gaskets for structural health monitoring. The signal of the integrated sensor exhibits a linear correlation with the contact pressure of the O-ring. This affords the opportunity to monitor the gasket condition during installation. Thus, damages caused by faulty assembly can be detected instantly, and early failures, with their associated consequences, can be prevented. Through the embedded strain gauge, the contact pressure applied to the gasket can be directly measured. Excessive pressure and incorrect positioning of the gasket can cause structural damage to the material of the gasket, which can lead to an early outage. A platinum strain gauge is fabricated on a thin polyimide layer and is contacted through gold connections. The measured resistance pressure response exhibits hysteresis for the first few strain cycles, followed by a linear behavior. The short-term impact of the embedded sensor on the stability of the gasket is investigated. Pull-tests with O-rings and test specimens have indicated that the integration of the miniaturized sensors has no negative impact on the stability in the short term.

  10. Analytical method for distribution of metallic gasket contact stress

    NASA Astrophysics Data System (ADS)

    Feng, Xiu; Gu, Boqing; Wei, Long; Sun, Jianjun

    2008-11-01

    Metallic gasket seals have been widely used in chemical and petrochemical plants. The failure of sealing system will lead to enormous pecuniary loss, serious environment pollution and personal injury accident. The failure of sealing systems is mostly caused not by the strength of flanges or bolts but by the leakage of the connections. The leakage behavior of bolted flanged connections is related to the gasket contact stress. In particular, the non-uniform distribution of this stress in the radial direction caused by the flange rotational flexibility has a major influence on the tightness of bolted flanged connections. In this paper, based on Warters method and considering the operating pressure, the deformation of the flanges is analyzed theoretically, and the formula for calculating the angle of rotation of the flanges is derived, based on which and the mechanical property of the gasket material, the method for calculating the gasket contact stresses is put forward. The maximum stress at the gasket outer flank calculated by the analytical method is lower than that obtained by numerical simulation, but the mean stresses calculated by the two methods are nearly the same. The analytical method presented in this paper can be used as an engineering method for designing the metallic gasket connections.

  11. Improved Rhenium Thrust Chambers

    NASA Technical Reports Server (NTRS)

    O'Dell, John Scott

    2015-01-01

    Radiation-cooled bipropellant thrust chambers are being considered for ascent/ descent engines and reaction control systems on various NASA missions and spacecraft, such as the Mars Sample Return and Orion Multi-Purpose Crew Vehicle (MPCV). Currently, iridium (Ir)-lined rhenium (Re) combustion chambers are the state of the art for in-space engines. NASA's Advanced Materials Bipropellant Rocket (AMBR) engine, a 150-lbf Ir-Re chamber produced by Plasma Processes and Aerojet Rocketdyne, recently set a hydrazine specific impulse record of 333.5 seconds. To withstand the high loads during terrestrial launch, Re chambers with improved mechanical properties are needed. Recent electrochemical forming (EL-Form"TM") results have shown considerable promise for improving Re's mechanical properties by producing a multilayered deposit composed of a tailored microstructure (i.e., Engineered Re). The Engineered Re processing techniques were optimized, and detailed characterization and mechanical properties tests were performed. The most promising techniques were selected and used to produce an Engineered Re AMBR-sized combustion chamber for testing at Aerojet Rocketdyne.

  12. Gondola-shaped tetra-rhenium metallacycles modified evanescent wave infrared chemical sensors for selective determination of volatile organic compounds.

    PubMed

    Huang, Genin Gary; Lee, Chung-Jay; Tsai, Bo-Chan; Yang, Jyisy; Sathiyendiran, Malaichamy; Lu, Kuang-Lieh

    2011-07-15

    Water-stable and cavity-contained rhenium metallacycles were synthesized, and their ability to selectively interact with volatile organic compounds (VOCs) systematically studied using attenuated total reflection infrared (ATR-IR) spectroscopy. Integrating the unique properties of rhenium metallacycles into optical sensing technologies significantly improves selectivity in detecting aromatic compounds. To explore the interaction of rhenium metallacycles with VOCs, the surface of ATR sensing elements was modified with the synthesized rhenium metallacycles and used to detect VOCs. The results indicate that rhenium metallacycles have crown ether-like recognition sites, which can selectively interact with aromatic compounds, especially those bearing polar functional groups. The IR absorption bands of rhenium metallacycles shift significantly upon adsorption of aromatic VOCs, revealing a strong interaction between the tetra-rhenium metallacycles and guest aromatic compounds. Optimizing the thickness of the metallacycles coated on the surface of the sensing element led to rapid response in detection. The dynamic range of response was generally up to 30 mg/L with detection limits ca. 30 μg/L. Further studies of the effect of interferences indicate that recovery can be higher than 95% for most of the compounds tested. The results on the flow-cell device indicated that the performances were similar to a static detection system but the detection of VOCs can be largely simplified. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Application of gasket performance data for design and operation of low emissions, high-reliability gasketed joints

    SciTech Connect

    Waterland, A.F. III

    1996-07-01

    The MTI project No. 47, Test Methods for Non-Asbestos Gasket Materials, opened everyone`s eyes to the breadth of performance and use information for gasket materials. What the MTI has started has resulted in a quiet revolution in gasketing, and just in time. Today`s emissions and reliability mandates have created a situation whereby gasket materials can no longer be selected and designed into systems simply through practicable experience and personnel judgment. A defined engineering approach is required. Based on the work initiated by the MTI and furthered by groups such as ASME and PVRC, there now exists extensive performance data for all gasketing materials. This presentation addresses the existence and usage of the various MTI and PVRC-type performance data as a tool for initial material selection. With this background, a novel simplification to the future ASME code procedure is introduced which allows for a simple yet accurate means of applying this widely available data to an emissions` control program at the plant level.

  14. Sealing Force Increasing of ACM Gasket through Electron Beam Radiation

    NASA Astrophysics Data System (ADS)

    dos Santos, D. J.; Batalha, G. F.

    2011-01-01

    Rubber is an engineering material largely used as sealing parts, in form of O-rings, solid gaskets and liquid gaskets, materials applied in liquid state with posterior vulcanization and sealing. Stress relaxation is a rubber characteristic which impacts negatively in such industrial applications (rings and solid gaskets). This work has the purpose to investigate the use of electron beam radiation (EB) as a technology able to decrease the stress relaxation in acrylic rubber (ACM), consequently increasing the sealing capability of this material. ACM samples were irradiated with dose of 100 kGy and 250 kGy, its behavior was comparatively investigated using, dynamic mechanical analysis (DMA) and compression stress relaxation (CSR) experiments. The results obtained by DMA shown an increase of Tg and changes in dynamic mechanical behavior.

  15. Polycarbosilazane passivation on graphite foil used as gasket seal

    NASA Astrophysics Data System (ADS)

    Prette, A. L. G.; Haage, T.; Will, A.; Kolb, M.; Flores, O.; Günthner, M.; Motz, G.

    2013-12-01

    Gasket seals are often used in industry and laboratories where a leak-proof installation is needed in order to avoid loss of products or dangerous materials. Many of products transported inside tubes are at relatively high temperatures excluding polymeric gaskets. In the same line, many of transported materials contain solvents which can attack polymer sealings, therefore limiting their use. An alternative is to use graphite joints as sealings. These joints are a sandwich of graphite foil and stainless steel mesh as forming core. The problem that raises using graphite in contact with steel is that at temperatures of about 500 °C an interdiffusion of carbon on the steel structure occurs which produces adhesion of the graphite gasket on the metallic flange. Therefore this adhesion increases the time to change each gasket, since rests of previously adhered graphite has to be removed from the flange. In order to avoid the adhesion of the graphite on the flange, polycarbosilazane precursor was used as protective finishing on the graphite foil surface. After thermal transformation of the polymer into the corresponding PDC finishing, it acts in two manners: It avoids the direct contact between the carbon and the steel and it allows the sealing of liquids and gases. Adhesion tests were done and showed that the foils passivated with PDCs did not adhere to the steel flange. Moreover, the production methods and products are compatible to industrial environment and processes. The results found here show that the time to change the gasket in industry can be clearly reduced by using the PDC finishing on graphite gasket.

  16. 33 CFR 183.536 - Seals and gaskets in fuel filters and strainers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Seals and gaskets in fuel filters and strainers. 183.536 Section 183.536 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Standards § 183.536 Seals and gaskets in fuel filters and strainers. (a) (b) Each gasket and each...

  17. 33 CFR 183.536 - Seals and gaskets in fuel filters and strainers.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Seals and gaskets in fuel filters and strainers. 183.536 Section 183.536 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Standards § 183.536 Seals and gaskets in fuel filters and strainers. (a) (b) Each gasket and each...

  18. 33 CFR 183.536 - Seals and gaskets in fuel filters and strainers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Seals and gaskets in fuel filters and strainers. 183.536 Section 183.536 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Standards § 183.536 Seals and gaskets in fuel filters and strainers. (a) (b) Each gasket and each...

  19. 33 CFR 183.536 - Seals and gaskets in fuel filters and strainers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Seals and gaskets in fuel filters and strainers. 183.536 Section 183.536 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Standards § 183.536 Seals and gaskets in fuel filters and strainers. (a) (b) Each gasket and each...

  20. 33 CFR 183.536 - Seals and gaskets in fuel filters and strainers.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Seals and gaskets in fuel filters and strainers. 183.536 Section 183.536 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Standards § 183.536 Seals and gaskets in fuel filters and strainers. (a) (b) Each gasket and each...

  1. Liposomal forms of rhenium cluster compounds: enhancement of biological activity.

    PubMed

    Shtemenko, Natalia I; Zabitskaya, Elena D; Berzenina, Oksana V; Yegorova, Dina E; Shtemenko, Alexander V

    2008-08-01

    Liposomal formulations of dinuclear cluster rhenium (Re) compounds were used in biochemical trials. Interaction of liposomal forms of some Re compounds with red blood cells in experiments in vitro showed strong cell-stabilizing properties. In the models of tumor growth and hemolytic anemia in vivo, liposomal forms had better therapeutic effects in comparison with their solutions. The process of formation of liposomes of cluster Re compounds with different organic ligands was investigated by the method of electronic absorption spectra and mechanism of their interactions with lipids is proposed. Encapsulation of cluster Re compounds to lipid coating may have activation significance for the quadruple Re-Re bond.

  2. 10. Detail of center hangar doors and canvas gasket, dock ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Detail of center hangar doors and canvas gasket, dock no. 493. View to southwest. - Offutt Air Force Base, Looking Glass Airborne Command Post, Nose Docks, On either side of Hangar Access Apron at Northwest end of Project Looking Glass Historic District, Bellevue, Sarpy County, NE

  3. Synthesis of magnetic rhenium sulfide composite nanoparticles

    NASA Astrophysics Data System (ADS)

    Tang, Naimei; Tu, Weixia

    2009-10-01

    Rhenium sulfide nanoparticles are associated with magnetic iron oxide through coprecipitation of iron salts with tetramethylammonium hydroxide. Sizes of the formed magnetic rhenium sulfide composite particles are in the range 5.5-12.5 nm. X-ray diffraction and energy-dispersive analysis of X-rays spectra demonstrate the coexistence of Fe 3O 4 and ReS 2 in the composite particle, which confirm the formation of the magnetic rhenium sulfide composite nanoparticles. The association of rhenium sulfide with iron oxide not only keeps electronic state and composition of the rhenium sulfide nanoparticles, but also introduces magnetism with the level of 24.1 emu g -1 at 14 kOe. Surface modification with monocarboxyl-terminated poly(ethylene glycol) (MPEG-COOH) has the role of deaggregating the composite nanoparticles to be with average hydrodynamic size of 27.3 nm and improving the dispersion and the stability of the composite nanoparticles in water.

  4. Directed light fabrication of rhenium components

    SciTech Connect

    Milewski, J.O.; Thoma, D.J.; Lewis, G.K.

    1997-02-01

    Directed Light Fabrication (DLF) is a direct metal deposition process that fuses powder, delivered by gas into the focal zone of a high powered laser beam to form fully dense near-net shaped components. This is accomplished in one step without the use of molds, dies, forming, pressing, sintering or forging equipment. DLF is performed in a high purity inert environment free from the contaminants associated with conventional processing such as oxide and carbon pickup, lubricants, binding agents, cooling or cleaning agents. Applications using rhenium have historically been limited in part by its workability and cost. This study demonstrates the ability to fuse rhenium metal powder, using a DLF machine, into free standing rods and describes the associated parameter study. Microstructural comparisons between DLF deposited rhenium and commercial rhenium sheet product is performed. This research combined with existing DLF technology demonstrates the feasibility of forming complex rhenium, metal shapes directly from powder.

  5. Properties of tungsten-rhenium and tungsten-rhenium with hafnium carbide

    NASA Astrophysics Data System (ADS)

    Leonhardt, Todd

    2009-07-01

    Historically, tungsten-25wt.% rhenium alloy has been manufactured into wire for the thermocouple market, but recent demands for high-temperature structural components have forced the development of novel processing techniques for tungsten-rhenium and tungsten-rhenium with hafnium carbide. With a melting temperature of 3,050°C, and a recrystallization temperature near 1,900°C, tungsten-rhenium alloys are being used in aerospace, temperature measuring, and friction stir welding applications. The mechanical properties and microstructures of tungsten-25wt.% rhenium and tungsten-25wt.% rhenium with hafnium carbide are reported at ambient temperature, 1,371°C, and 1,926°C, after processing by three methods: hot isostatic pressing, swaging, and extrusion.

  6. Catalytic reforming with rhenium-platinum catalyst containing more rhenium than platinum

    SciTech Connect

    Gallagher, J.P.; Yarrington, R.M.

    1982-10-26

    A new reforming process employs a new rhenium-platinum catalytic composite having a rhenium to platinum weight ratio in the range of not less than 2 to about 5, whereby longer relative cycle length is obtained when reforming a naphtha having less than about 0.5 ppm by weight of sulfur than if the rhenium-platinum ratio is outside of such range.

  7. Testing of Wrought Iridium/Chemical Vapor Deposition Rhenium Rocket

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.; Schneider, Steven J.

    1996-01-01

    A 22-N class, iridium/rhenium (Ir/Re) rocket chamber, composed of a thick (418 miocrometer) wrought iridium (Ir) liner and a rhenium substrate deposited via chemical vapor deposition, was tested over an extended period on gaseous oxygen/gaseous hydrogen (GO2/GH2) propellants. The test conditions were designed to produce species concentrations similar to those expected in an Earth-storable propellant combustion environment. Temperatures attained in testing were significantly higher than those expected with Earth-storable propellants, both because of the inherently higher combustion temperature of GO2/GH2 propellants and because the exterior surface of the rocket was not treated with a high-emissivity coating that would be applied to flight class rockets. Thus the test conditions were thought to represent a more severe case than for typical operational applications. The chamber successfully completed testing (over 11 hr accumulated in 44 firings), and post-test inspections showed little degradation of the Ir liner. The results indicate that use of a thick, wrought Ir liner is a viable alternative to the Ir coatings currently used for Ir/Re rockets.

  8. Rhenium/Oxygen Interactions at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan; Myers, Dwight; Zhu, Dong-Ming; Humphrey, Donald

    2000-01-01

    The oxidation of pure rhenium is examined from 600-1400 C in oxygen/argon mixtures. Linear weight loss kinetics are observed. Gas pressures, flow rates, and temperatures are methodically varied to determine the rate controlling steps. The reaction at 600 and 800 C appears to be controlled by a chemical reaction step at the surface; whereas the higher temperature reactions appear to be controlled by gas phase diffusion of oxygen to the rhenium surface. Attack of the rhenium appears to be along grain boundaries and crystallographic planes.

  9. The development and testing of asbestos-free gasket materials

    SciTech Connect

    Mallow, W.A. )

    1992-01-01

    Of the 27 vendors contacted, 11 submitted asbestos-free gasket materials for thermal analysis followed by hydrostatic pressure testing, steam pressure testing, and fire testing. Virtually all were acceptable up to 400 C (air-free), and most were stable to 700 C. Several can be used to over 900 C in air or gases, since they are ceramic. Several graphitic gaskets are serviceable to 900 C in absence of air. Several performed well in steam pressure testing to 315 C, requiring a single adjustment in bolt/flange pressure after pressurization. Many acquired a compression set and consequent slight pressure loss, but responded well to bolt tightening. All except one are made of compressed ceramic or graphite fiber with 0-35 wt% binder, hence was inelastic but malleable/compressible. The large number of ceramic-and graphitic-based gasket materials obviated the need for further development; efforts were concentrated on critical evaluation of the off-the-shelf available materials, in comparison with asbestos.

  10. Rhenium alloying of tungsten heavy alloys

    SciTech Connect

    German, R.M.; Bose, A.; Jerman, G.

    1989-01-01

    Alloying experiments were performed using rhenium additions to a classic 90 mass % tungsten heavy alloy. The mixed-powder system was liquid phase sintered to full density at 1500 C in 60 min The rhenium-modified alloys exhibited a smaller grain size, higher hardness, higher strength, and lower ductility than the unalloyed system. For an alloy with a composition of 84W-6Re-8Ni-2Fe, the sintered density was 17, 4 Mg/m{sup 3} with a yield strength of 815 MPa, tensile strength of 1180 MPa, and elongation to failure of 13%. This property combination results from the aggregate effects of grain size reduction and solid solution hardening due to rhenium. In the unalloyed system these properties require post-sintering swaging and aging; thus, alloying with rhenium is most attractive for applications where net shaping is desired, such as by powder injection molding.

  11. A simple aluminum gasket for use with both stainless steel and aluminum flanges

    SciTech Connect

    Langley, R.A.

    1991-01-01

    A technique has been developed for making aluminum wire seal gaskets of various sizes and shapes for use with both stainless steel and aluminum alloy flanges. The gasket material used is 0.9999 pure aluminum, drawn to a diameter of 3 mm. This material can be easily welded and formed into various shapes. A single gasket has been successfully used up to five times without baking. The largest gasket tested to date is 3.5 m long and was used in the shape of a parallelogram. Previous use of aluminum wire gaskets, including results for bakeout at temperatures from 20 to 660{degree}C, is reviewed. A search of the literature indicates that this is the first reported use of aluminum wire gaskets for aluminum alloy flanges. The technique is described in detail, and the results are summarized. 11 refs., 4 figs.

  12. Mineral resource of the month: rhenium

    USGS Publications Warehouse

    Polyak, Désirée E.

    2012-01-01

    Rhenium, a silvery-white, heat resistant metal, has increased significantly in importance since its discovery in 1925. First isolated by a team of German chemists studying platinum ore, the mineral was named for the Rhine River. From 1925 until the 1960s, only two metric tons of rhenium were produced worldwide. Since then, its uses have steadily increased, including everything from unleaded gasoline to jet engines, and worldwide annual production now tops 45 metric tons.

  13. Rhenium-Oxygen Interactions at High Temperatures

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Myers, Dwight L.; Zhu, Dongming; Humphrey, Donald

    2000-01-01

    The reaction of pure rhenium metal with dilute oxygen/argon mixtures was studied from 600 to 1400 C. Temperature, oxygen pressure, and flow rates were systematically varied to determine the rate-controlling steps. At lower temperatures the oxygen/rhenium chemical reaction is rate limiting; at higher temperatures gas-phase diffusion of oxygen through the static boundary layer is rate limiting. At all temperatures post-reaction microstructures indicate preferential attack along certain crystallographic planes and defects.

  14. Optimization of Gasket Materials for Metal Packing Containers for Mortar Ammunition

    DTIC Science & Technology

    2002-01-01

    The current contractor (B-Way Corporation) performed the tests in October 2001 and agreed that the neoprene gasket performs as well or even better...butadinene (SBR) Ethylene propylene diene ( EPDM ) Natural rubber (60) Natural rubber (40) 120-mm metal container 81-mm metal container Gasket materials 16...environment and material testing . Based on successful testing , an engineering change proposal (ECP) will be submitted to implement the best gasket material

  15. Experiences with new European standards for calculation of flanged joints including necessary gasket factors

    SciTech Connect

    Bartonicek, J.; Kockelmann, H.; Schoeckle, F.

    1996-12-01

    The correct function of a flanged joint in a given construction (flanges, bolts) and with given loads (pressure, temperature, additional forces) depends on the following: (1) choice of the gasket for the operation environment; (2) determination of the gasket stress for assembly conditions; and (3) gasket stress in operation, i.e., the conditions when leakage has to be minimized. For the correct choice of a gasket it is necessary to have gasket factors available, as given by DIN 28090 (Sept. 95) together with the test procedures. These gasket factors determine the tightening characteristics as well as the deformation capability of the gaskets. Furthermore, these gasket factors must be available for use in calculations. On the basis of calculations a stress analysis (i.e. a limitation of the stresses in flanges and bolts) must be possible as well as the determination of the bolt forces for the assembly state and of the gasket stress for operating conditions. This is one of the goals of the standard pr DIN EN 1591. The paper first introduces the actual European standards. Calculations are reviewed using test data from special test rigs and from real flanged joints. The calculations were made according to DIN 2505 (initial German standard for flanged joints) and pr DIN EN 1591. Additionally, 2D and 3D Finite Element analysis calculations were performed.

  16. Rhenium(IV) sulfide nanotubes.

    PubMed

    Brorson, Michael; Hansen, Thomas W; Jacobsen, Claus J H

    2002-10-02

    Rhenium(IV) sulfide, ReS(2), has been prepared with nanotubular morphology by carbon nanotube templating. A multiwall carbon nanotube material was impregnated with solutions of NH(4)ReO(4) or ReCl(5), followed by drying and sulfidation with H(2)S at 1000 degrees C. The composite material synthesized was characterized by high-resolution transmission electron microscopy and X-ray powder diffraction. Like previously described MS(2) nanotube compounds, ReS(2) has a layered structure consisting of S-M-S layers. Re atoms in ordinary ReS(2) are octahedrally coordinated with S, and tetranuclear metal clusters are present as a consequence of metal-metal bonds.

  17. Recovery of rhenium from sulfuric acid solutions with activated coals

    SciTech Connect

    Troshkina, I.D.; Naing, K.Z.; Ushanova, O.N.; P'o, V.; Abdusalomov, A.A.

    2006-09-15

    Equilibrium and kinetic characteristics of rhenium sorption from sulfuric acid solutions (pH 2) by activated coals produced from coal raw materials (China) were studied. Constants of the Henry equation describing isotherms of rhenium sorption by activated coals were calculated. The effective diffusion coefficients of rhenium in the coals were determined. The dynamic characteristics of rhenium sorption and desorption were determined for the activated coal with the best capacity and kinetic characteristics.

  18. Determining rhenium in weak processing solutions

    SciTech Connect

    Koval', L.B.

    1986-09-01

    Analytical methods of determining rhenium in production solutions and solid materials almost always include a stage of separating molybdenum, since these elements occur together in molybdenum ores and concentrates. The authors have developed a method of analysis for rhenium in low-concentration industrial solutions containing a complicated set of impurities. The molybdenum is separated from rhenium in a separating funnel and the acidity is brought to 1 M. A 20% solution of KCNS is added together with ascorbic acid. The funnel is shaken for 1-2 min and left to stand until the molybdenum is completely reduced (5-10 min), and then the thiocyanate complex of the molybdenum is extracted with diethyl ether. The lower water layer is transferred to a volumetric flask and the necessary reagents are added to reduce the rhenium and produce the yellow-orange rhenium thiocyanate complex. The peak optical density of the complex is measured with a photocolorimeter and the absorption spectra are recorded with a spectrophotometer.

  19. Liquid fluorine/hydrazine rhenium thruster update

    NASA Technical Reports Server (NTRS)

    Appel, M. A.; Kaplan, R. B.; Tuffias, R. H.

    1983-01-01

    The status of a fluorine/hydrazine thruster development program is discussed. A solid rhenium metal sea-level thrust chamber was successfully fabricated and tested for a total run duration of 1075 s with 17 starts. Rhenium fabrication methods are discussed. A test program was conducted to evaluate performance and chamber cooling. Acceptable performance was reached and cooling was adequate. A flight-type injector was fabricated that achieved an average extrapolated performance value of 3608 N-s/kg (368 lbf-s/lbm). Altitude thrust chambers were fabricated. One chamber incorporates a rhenium combustor and nozzle with an area ratio of 15:1, and a columbium nozzle extension with area ratios from 15:1 to 60:1. The other chamber was fabricated completely with a carbon/carbon composite. Because of the attributes of rhenium for use in high-temperature applications, a program to provide the materials and processes technology needed to reliably fabricate and/or repair vapor-deposited rhenium parts of relatively large size and complex shape is recommended.

  20. Liquid fluorine/hydrazine rhenium thruster update

    NASA Technical Reports Server (NTRS)

    Appel, M. A.; Kaplan, R. B.; Tuffias, R. H.

    1983-01-01

    The status of a fluorine/hydrazine thruster development program is discussed. A solid rhenium metal sea-level thrust chamber was successfully fabricated and tested for a total run duration of 1075 s with 17 starts. Rhenium fabrication methods are discussed. A test program was conducted to evaluate performance and chamber cooling. Acceptable performance was reached and cooling was adequate. A flight-type injector was fabricated that achieved an average extrapolated performance value of 3608 N-s/kg (368 lbf-s/lbm). Altitude thrust chambers were fabricated. One chamber incorporates a rhenium combustor and nozzle with an area ratio of 15:1, and a columbium nozzle extension with area ratios from 15:1 to 60:1. The other chamber was fabricated completely with a carbon/carbon composite. Because of the attributes of rhenium for use in high-temperature applications, a program to provide the materials and processes technology needed to reliably fabricate and/or repair vapor-deposited rhenium parts of relatively large size and complex shape is recommended.

  1. 46 CFR 56.25-15 - Gaskets (modifies 108.4).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Gaskets (modifies 108.4). 56.25-15 Section 56.25-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND... operating temperature exceeds -750 °F. (d) The use of metal and nonmetallic gaskets is not limited as...

  2. 46 CFR 56.25-15 - Gaskets (modifies 108.4).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Gaskets (modifies 108.4). 56.25-15 Section 56.25-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND... operating temperature exceeds -750 °F. (d) The use of metal and nonmetallic gaskets is not limited as...

  3. 46 CFR 56.25-15 - Gaskets (modifies 108.4).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Gaskets (modifies 108.4). 56.25-15 Section 56.25-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND... operating temperature exceeds -750 °F. (d) The use of metal and nonmetallic gaskets is not limited as...

  4. Rubber and alumina gaskets retain vacuum seal in high temperature EMF cell

    NASA Technical Reports Server (NTRS)

    Hesson, J. C.

    1966-01-01

    Silicone rubber gasket and an alumina gasket retain a vacuum inside a high temperature EMF cell in which higher and lower density liquid metal electrodes are separated by an intermediate density fused salt electrolyte. This innovation is in use on a sodium bismuth regenerable EMF cell in which the fused salts and metals are at about 500 deg to 600 deg C.

  5. Characterization of Rhenium Oxides Using ESCA

    NASA Technical Reports Server (NTRS)

    Panda, Binayak; Jones, Clyde S. (Technical Monitor)

    2001-01-01

    Rhenium as an engineering material has the following properties: (1) high melting point (one of the refractory metals); (2) high strength at elevated temperatures; (3) excellent toughness at room temperature; (4) low vapor pressure at melting point; (5) low coefficient of thermal expansion; (6) high impact and wear resistance; (7) compatibility with elements such as carbon and platinum; (8) conservation of properties in the presence of hydrogen, water vapor, and nitrogen oxides; and (9) poor oxidation resistance. This viewgraph presentation gives an overview of rhenium oxide characterization, including details on its history, experimental procedure using ESCA, and the analysis of the oxides (spectra and effects of ion sputtering).

  6. Size and Shape of Rhenium Nanoparticles

    NASA Astrophysics Data System (ADS)

    Yang, N.; Mickelson, G. E.; Greenlay, N.; Kelly, S. D.; Vila, F. D.; Kas, J.; Rehr, J. J.; Bare, Simon R.

    2007-02-01

    In this paper the results from a detailed XAFS characterization of supported rhenium nanoparticles are presented. The Re nanoparticles are formed by the reduction of dispersed supported rhenium oxide in the presence of moist hydrogen. The shape of the wet—reduced Re clusters is determined by comparing the EXAFS spectra of Re-metal to the Re-wet-reduced clusters to 6 Å. A decrease in the signal from the 4th and 7th Re shells is an indication of sheet-like rather than spherical-like particles.

  7. Size and Shape of Rhenium Nanoparticles

    SciTech Connect

    Yang, N.; Mickelson, G. E.; Greenlay, N.; Bare, Simon R.; Kelly, S. D.; Vila, F. D.; Kas, J.; Rehr, J. J.

    2007-02-02

    In this paper the results from a detailed XAFS characterization of supported rhenium nanoparticles are presented. The Re nanoparticles are formed by the reduction of dispersed supported rhenium oxide in the presence of moist hydrogen. The shape of the wet--reduced Re clusters is determined by comparing the EXAFS spectra of Re-metal to the Re-wet-reduced clusters to 6 A. A decrease in the signal from the 4th and 7th Re shells is an indication of sheet-like rather than spherical-like particles.

  8. Size and shape of rhenium nanoparticles.

    SciTech Connect

    Yang, N.; Mickelson, G. E.; Greenlay, N.; Kelly, S. D.; Vila, F. D.; Kas, J.; Rehr, J. J.; Bare, S. R.; X-Ray Science Division; UOP LLC; EXAFS; Univ. of Washington

    2007-01-01

    In this paper the results from a detailed XAFS characterization of supported rhenium nanoparticles are presented. The Re nanoparticles are formed by the reduction of dispersed supported rhenium oxide in the presence of moist hydrogen. The shape of the wet-reduced Re clusters is determined by comparing the EXAFS spectra of Re-metal to the Re-wet-reduced clusters to 6 {angstrom}. A decrease in the signal from the 4th and 7th Re shells is an indication of sheet-like rather than spherical-like particles.

  9. Testing of electroformed deposited iridium/powder metallurgy rhenium rockets

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.; Dickerson, Robert

    1996-01-01

    High-temperature, oxidation-resistant chamber materials offer the thermal margin for high performance and extended lifetimes for radiation-cooled rockets. Rhenium (Re) coated with iridium (Ir) allow hours of operation at 2200 C on Earth-storable propellants. One process for manufacturing Ir/Re rocket chambers is the fabrication of Re substrates by powder metallurgy (PM) and the application of Ir coatings by using electroformed deposition (ED). ED Ir coatings, however, have been found to be porous and poorly adherent. The integrity of ED Ir coatings could be improved by densification after the electroforming process. This report summarizes the testing of two 22-N, ED Ir/PM Re rocket chambers that were subjected to post-deposition treatments in an effort to densify the Ir coating. One chamber was vacuum annealed, while the other chamber was subjected to hot isostatic pressure (HIP). The chambers were tested on gaseous oxygen/gaseous hydrogen propellants, at mixture ratios that simulated the oxidizing environments of Earth-storable propellants. ne annealed ED Ir/PM Re chamber was tested for a total of 24 firings and 4.58 hr at a mixture ratio of 4.2. After only 9 firings, the annealed ED Ir coating began to blister and spall upstream of the throat. The blistering and spalling were similar to what had been experienced with unannealed, as-deposited ED Ir coatings. The HIP ED Ir/PM Re chamber was tested for a total of 91 firings and 11.45 hr at mixture ratios of 3.2 and 4.2. The HIP ED Ir coating remained adherent to the Re substrate throughout testing; there were no visible signs of coating degradation. Metallography revealed, however, thinning of the HIP Ir coating and occasional pores in the Re layer upstream of the throat. Pinholes in the Ir coating may have provided a path for oxidation of the Re substrate at these locations. The HIP ED Ir coating proved to be more effective than vacuum annealed and as-deposited ED Ir. Further densification is still required to

  10. Nanograined Net-Shaped Fabrication of Rhenium Components by EB-PVD

    SciTech Connect

    Singh, Jogender; Wolfe, Douglas E.

    2004-02-04

    Cost-effective net-shaped forming components have brought considerable interest into DoD, NASA and DoE. Electron beam physical vapor deposition (EB-PVD) offers flexibility in forming net-shaped components with tailored microstructure and chemistry. High purity rhenium (Re) components including rhenium-coated graphite balls, Re- plates and tubes have been successfully manufactured by EB-PVD. EB-PVD Re components exhibited sub-micron and nano-sized grains with high hardness and strength as compared to CVD. It is estimated that the cost of Re components manufactured by EB-PVD would be less than the current CVD and powder-HIP Technologies.

  11. Elastic module of superhard rhenium diboride

    SciTech Connect

    Koehler, Michael R.; Keppens, Veerle; Sales, Brian C; Jin, Rongying; Mandrus, David

    2009-01-01

    The elastic moduli of polycrystalline rhenium diboride are measured as a function of temperature between 5 and 325 K. The room temperature results show that ReB{sub 2} has very high values for both the bulk and shear modulus, confirming the incompressible and superhard nature of this material. With decreasing temperature, the moduli increase, with a hint of softening below 50 K.

  12. Magnet coil electrical gaskets of high compliance and ampacity

    SciTech Connect

    Harvey, A.R.; Yamamoto, R.M.

    1995-05-17

    Coils employed in the magnets of the PHENIX Detector, presently under construction for RHIC (Relativistic Heavy Ion Collider) at the Brookhaven National Laboratory, are massive (weight {approximately} 8000 kG each). For that reason we subdivided them into a series of manageable subcoils that we will subsequent bolt together. Electrical terminals attached to the subcoils conductors are rigidly embedded and precisely located during vacuum impregnation. However; we anticipate some misalignment and nonuniform gaping to occur between terminals at assembly. We have elected to use electrical gaskets of compliance and ampacity between the bolted terminals to enhance the current carrying capability of the electrical joints. This paper describes the material candidates selected, the tests performed, and the relative ranking of the materials tested.

  13. A Digital Image Steganography using Sierpinski Gasket Fractal and PLSB

    NASA Astrophysics Data System (ADS)

    Rupa, Ch.

    2013-09-01

    Information attacks are caused due to the weaknesses in the information security. These attacks affect the non-repudiation and integrity of the security services. In this paper, a novel security approach that can defend the message from information attacks is proposed. In this new approach the original message is encrypted by Fractal Sierpinski Gasket (FSG) cryptographic algorithm, that result is hidden into an image using penultimate and least significant bit (PLSB) embedding method. This method makes the security more robust than conventional approach. Important properties of fractals are sensitivity and self similarity. These can be exploited to produce avalanche effect. Stegoanalysis of the proposed method shows that it is resistant to various attacks and stronger than the existed steganographic approaches.

  14. Accelerator Production and Separations for High Specific Activity Rhenium-186

    SciTech Connect

    Jurisson, Silvia S.; Wilbur, D. Scott

    2016-04-01

    Tungsten and osmium targets were evaluated for the production of high specific activity rhenium-186. Rhenium-186 has potential applications in radiotherapy for the treatment of a variety of diseases, including targeting with monoclonal antibodies and peptides. Methods were evaluated using tungsten metal, tungsten dioxide, tungsten disulfide and osmium disulfide. Separation of the rhenium-186 produced and recycling of the enriched tungsten-186 and osmium-189 enriched targets were developed.

  15. Coatings.

    ERIC Educational Resources Information Center

    Anderson, Dennis G.

    1989-01-01

    This review covers analytical techniques applicable to the examination of coatings, raw materials, and substrates upon which coatings are placed. Techniques include chemical and electrochemical methods, chromatography, spectroscopy, thermal analysis, microscopy, and miscellaneous techniques. (MVL)

  16. Coatings.

    ERIC Educational Resources Information Center

    Anderson, Dennis G.

    1989-01-01

    This review covers analytical techniques applicable to the examination of coatings, raw materials, and substrates upon which coatings are placed. Techniques include chemical and electrochemical methods, chromatography, spectroscopy, thermal analysis, microscopy, and miscellaneous techniques. (MVL)

  17. Integrated-fin gasket for palm cubic-anvil high pressure apparatus

    SciTech Connect

    Cheng, J.-G.; Matsubayashi, K.; Nagasaki, S.; Hisada, A.; Hirayama, T.; Uwatoko, Y.; Hedo, M.; Kagi, H.

    2014-09-15

    We described an integrated-fin gasket technique for the palm cubic-anvil apparatus specialized for the high-pressure and low-temperature measurements. By using such a gasket made from the semi-sintered MgO ceramics and the tungsten-carbide anvils of 2.5 mm square top, we successfully generate pressures over 16 GPa at both room and cryogenic temperatures down to 0.5 K. We observed a pressure self-increment for this specific configuration and further characterized the thermally induced pressure variation by monitoring the antiferromagnetic transition temperature of chromium up to 12 GPa. In addition to enlarge the pressure capacity, such a modified gasket also improves greatly the surviving rate of electrical leads hanging the sample inside a Teflon capsule filled with the liquid pressure-transmitting medium. These improvements should be attributed to the reduced extrusion of gasket materials during the initial compression.

  18. ITEP MEVVA ion beam for rhenium silicide production

    SciTech Connect

    Kulevoy, T.; Seleznev, D.; Kropachev, G.; Kozlov, A.; Kuibeda, R.; Yakushin, P.; Petrenko, S.; Gerasimenko, N.; Medetov, N.; Zaporozhan, O.

    2010-02-15

    The rhenium silicides are very attractive materials for semiconductor industry. In the Institute for Theoretical and Experimental Physics (ITEP) at the ion source test bench the research program of rhenium silicide production by ion beam implantation are going on. The investigation of silicon wafer after implantation of rhenium ion beam with different energy and with different total dose were carried out by secondary ions mass spectrometry, energy-dispersive x-ray microanalysis, and x-ray diffraction analysis. The first promising results of rhenium silicide film production by high intensity ion beam implantation are presented.

  19. Investigation of extrusion failures of PTFE-based gaskets in chemical plant service

    SciTech Connect

    Winter, J.R.; Keywood, S.S.

    1996-12-01

    PTFE-based gaskets in chemical plant service typically fail in an extrusion mode, sometimes referred to as blowout. Test work previously published by Monsanto indicated that correctly installed PTFE-based gaskets have pressure performance far exceeding system pressure ratings. These results have since been confirmed by extensive testing at the Montreal based Ecole Polytechnique Tightness Testing and Research Laboratory (TTRL), funded by a consortium of gasket users and manufacturers. With the knowledge that properly installed gaskets can withstand system pressures in excess of 1,000 psig [6,894 kPa], failures at two chemical plants were re-examined. This analysis indicates that extrusion type failures can be caused by excessive internal pressures, associated with sections of pipe having an external source of heat coincident with a blocked flow condition. This results in high system pressures which explain the extrusion type failures observed. The paper discusses details of individual failures and examines methods to prevent them. Other causes for extrusion failures are reviewed, with a recommendation that stronger gasket materials not be utilized to correct problems until it is verified that excessive pressure build-up is not the problem. Also summarized are the requirements for proper installation to achieve the potential blowout resistance found in these gaskets.

  20. Characterization of Rhenium Oxides Using ESCA

    NASA Technical Reports Server (NTRS)

    Panda, Binayak; Gentz, Steven J. (Technical Monitor)

    2001-01-01

    High melting point and inherent ductility (toughness) over a wide range of temperature has made Rhenium an engineering material of choice for several thrust chambers in propulsion systems. Although the material remains tough at high temperatures, it still can readily transform to several oxides. As many as eight different oxides have been reported in literature. When characterized using ESCA (Electron Spectroscopy for Chemical Analyses) these oxides show large shifts in the Re 4f line positions. While this unique property could be used as a tool for oxide characterization, literature indicates that only a few of these oxides have been characterized. Current work focuses on characterizing oxides of Rhenium using ESCA. Spectral line Re 4f have been measured for various oxides and the results have been compared with the Re 4f line positions of real-time oxidation products from space hardware.

  1. Rhenium ion beam for implantation into semiconductors

    SciTech Connect

    Kulevoy, T. V.; Seleznev, D. N.; Alyoshin, M. E.; Kraevsky, S. V.; Yakushin, P. E.; Khoroshilov, V. V.; Gerasimenko, N. N.; Smirnov, D. I.; Fedorov, P. A.; Temirov, A. A.

    2012-02-15

    At the ion source test bench in Institute for Theoretical and Experimental Physics the program of ion source development for semiconductor industry is in progress. In framework of the program the Metal Vapor Vacuum Arc ion source for germanium and rhenium ion beam generation was developed and investigated. It was shown that at special conditions of ion beam implantation it is possible to fabricate not only homogenous layers of rhenium silicides solid solutions but also clusters of this compound with properties of quantum dots. At the present moment the compound is very interesting for semiconductor industry, especially for nanoelectronics and nanophotonics, but there is no very developed technology for production of nanostructures (for example quantum sized structures) with required parameters. The results of materials synthesis and exploration are presented.

  2. Characterization of Rhenium Oxides Using ESCA

    NASA Technical Reports Server (NTRS)

    Panda, Binayak; Gentz, Steven J. (Technical Monitor)

    2001-01-01

    High melting point and inherent ductility (toughness) over a wide range of temperature has made Rhenium an engineering material of choice for several thrust chambers in propulsion systems. Although the material remains tough at high temperatures, it still can readily transform to several oxides. As many as eight different oxides have been reported in literature. When characterized using ESCA (Electron Spectroscopy for Chemical Analyses) these oxides show large shifts in the Re 4f line positions. While this unique property could be used as a tool for oxide characterization, literature indicates that only a few of these oxides have been characterized. Current work focuses on characterizing oxides of Rhenium using ESCA. Spectral line Re 4f have been measured for various oxides and the results have been compared with the Re 4f line positions of real-time oxidation products from space hardware.

  3. Unusual Metalloporphyrin Complexes of Rhenium and Technetium

    DTIC Science & Technology

    1975-06-06

    homodinuclear porphyrins are centrosymmetric complexes having two metals bonded to the porphyrin, one above and one below the plane of the macrocycle while the...may be said about tnt structural details of the porphyrin macrocycle . S1U 6 Resu’i ts: Unusual Rhenium Metalloporphyrin Complexes Reflux of decalin...purphyrin, one above and one below the plane of the macrocyclic ligand. A comparison of these two complexes of Group Vllb congeners is of interest. The X-ray

  4. Rhenium Radioisotopes for Therapeutic Radiopharmaceutical Development

    SciTech Connect

    Beets, A.L.; Knapp, F.F., Jr.; Kropp, J.; Lin, W.-Y.; Pinkert, J.; Wang, S.-Y.

    1999-01-18

    The availability of therapeutic radioisotopes at reasonable costs is important for applications in nuclear medicine, oncology and interventional cardiology, Rhenium-186 (Re-186) and rhenium-1 88 (Re-188) are two reactor-produced radioisotope which are attractive for a variety of therapeutic applications, Rhenium-186 has a half-life of 90 hours and decays with emission of a &particle with a maximum energy of 1.08 MeV and a 135 keV (9Yo) gamma which permits imaging. In contrast, Re- 188 has a much shorter half-life of 16.9 hours and emits a p-particle with a much higher energy of 2.12 MeV (Em=) and a 155 keV gamma photon (15Yo) for imaging. While Re-186 is unavailable from a generator system and must be directly produced in a nuclear reactor, Re-188 can also be directly produced in a reactor with high specific activity, but is more conveniently and cost-effectively available as carrier-free sodium perrhenate by saline elution of the alumina-based tungsten-188 (W1 88)/Re-l 88 generator system [1-2]. Since a comprehensive overviewofRe-186 and Re-188 therapeutic agents is beyond the scope of this &tended Abstrac4 the goal is to provide key examples of various agents currently in clinical use and those which are being developed for important clinical applications.

  5. Rhenium: a rare metal critical in modern transportation

    USGS Publications Warehouse

    John, David A.

    2015-01-01

    Rhenium rarely occurs as a native element or as its own sulfide mineral—rheniite (ReS2)—and often occurs as a substitute for molybdenum in molybdenite (MoS2). Most extracted rhenium is a byproduct of copper mining, with about 80 percent recovered from flue dust during the processing of molybdenite concentrates from porphyry copper deposits.

  6. Cellular uptake and cytotoxicity of octahedral rhenium cluster complexes.

    PubMed

    Choi, Soo-Jin; Brylev, Konstantin A; Xu, Jing-Zhe; Mironov, Yuri V; Fedorov, Vladimir E; Sohn, Youn Soo; Kim, Sung-Jin; Choy, Jin-Ho

    2008-11-01

    Cellular uptake behavior of a novel class of octahedral rhenium cluster compounds, hexahydroxo complexes K(4)[{Re(6)S(8)}(OH)(6)].8H(2)O (1) and K(4)[{Re(6)Se(8)}(OH)(6)].8H(2)O (2), was evaluated in human cervical adenocarcinoma HeLa cells. Confocal microscopy and flow cytometry studies demonstrated that rhenium cluster 1 was not internalized into cell, while rhenium cluster 2 was. Conjugation of a polymer to rhenium cluster 1, namely the derivative K(4)[{Re(6)S(8)}(OH)(5)L] (3) (L is amphiphilic diblock copolymer MPEG550-CH(2)CONH-GlyPheLeuGlyPheLeu-COO(-)), considerably enhanced cellular uptake in a concentration-dependent manner and was predominantly localized in the cytoplasm and nucleus upon incubation time. The uptake of rhenium cluster 2 was mediated by energy-dependent endocytosis, whereas rhenium cluster 3 was directly ingested into cells by cell-fusion-like mechanism. According to the cytotoxicity evaluation test, both rhenium clusters 2 and 3 did not exhibit acute cytotoxic effects up to 50 microM, at the practical concentration level of biological applications. It is, therefore, expected that the rhenium cluster complexes can be promising potential candidates as diagnostic agents for medical treatment.

  7. Airborne asbestos exposures associated with gasket and packing replacement: a simulation study and meta-analysis.

    PubMed

    Madl, Amy K; Hollins, Dana M; Devlin, Kathryn D; Donovan, Ellen P; Dopart, Pamela J; Scott, Paul K; Perez, Angela L

    2014-08-01

    Exposures to airborne asbestos during the removal and installation of internal gaskets and packing associated with a valve overhaul were characterized and compared to published data according to different variables (e.g., product, equipment, task, tool, setting, duration). Personal breathing zone and area samples were collected during twelve events simulating gasket and packing replacement, clean-up and clothing handling. These samples were analyzed using PCM and TEM methods and PCM-equivalent (PCME) airborne asbestos concentrations were calculated. A meta-analysis was performed to compare these data with airborne asbestos concentrations measured in other studies involving gaskets and packing. Short-term mechanic and assistant airborne asbestos concentrations during valve work averaged 0.013f/cc and 0.008f/cc (PCME), respectively. Area samples averaged 0.008f/cc, 0.005f/cc, and 0.003f/cc (PCME) for center, bystander, and remote background, respectively. Assuming a tradesman conservatively performs 1-3 gasket and/or packing replacements daily, an average 8-h TWA was estimated to be 0.002-0.010f/cc (PCME). Combining these results in a meta-analysis of the published exposure data showed that the majority of airborne asbestos exposures during work with gaskets and packing fall within a consistent and low range. Significant differences in airborne concentrations were observed between power versus manual tools and removal versus installation tasks. Airborne asbestos concentrations resulting from gasket and packing work during a valve overhaul are consistent with historical exposure data on replacement of asbestos-containing gasket and packing materials involving multiple variables and, in nearly all plausible scenarios, result in average airborne asbestos concentrations below contemporaneous occupational exposure limits for asbestos.

  8. Near-Net Shape Powder Metallurgy Rhenium Thruster

    NASA Technical Reports Server (NTRS)

    Leonhardt, Todd; Hamister, Mark; Carlen, Jan C.; Biaglow, James; Reed, Brian

    2001-01-01

    This paper describes the development of a method to produce a near-net shape (NNS) powder metallurgy (PM) rhenium combustion chamber of the size 445 N (100 lbf) used in a high performance liquid apogee engine. These engines are used in low earth Orbit and geostationary orbit for satellite positioning systems. The developments in near-net shape powder metallurgy rhenium combustion chambers reported in this paper will reduce manufacturing cost of the rhenium chambers by 25 percent, and reduce the manufacturing time by 30 to 40 percent. The quantity of rhenium metal powder used to produce a rhenium chamber is reduced by approximately 70 percent and the subsequent reduction in machining schedule and costs is nearly 50 percent.

  9. Field-electron emission microscopy of carbon-saturated rhenium

    NASA Astrophysics Data System (ADS)

    Bernatskii, D. P.; Pavlov, V. G.

    2017-06-01

    The growth of carbon structures on the surface of a rhenium point field emitter has been studied by field electron microscopy (FEM). It is established that graphene formation takes place on close-packed crystal faces of rhenium and leads to decrease in their work function. For rhenium exposed in benzene vapors, the formation of graphene islands requires a much longer time than that for iridium. Heating of carbon-saturated rhenium point field emitter up to temperatures close to its melting point with subsequent cooling does not lead to changes in the work function and FEM image of the emitter surface. The observed phenomena are explained by high solubility of carbon in rhenium.

  10. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa

    SciTech Connect

    Meier, Thomas; Haase, Jürgen

    2015-12-15

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al{sub 2}O{sub 3}), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures.

  11. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa.

    PubMed

    Meier, Thomas; Haase, Jürgen

    2015-12-01

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al2O3), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures.

  12. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa

    NASA Astrophysics Data System (ADS)

    Meier, Thomas; Haase, Jürgen

    2015-12-01

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al2O3), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures.

  13. Gaskets of teflon-bonded EPDM halt leakage from acid lines - low sealing force design eliminates flange distress

    SciTech Connect

    Walker, I.S.; Gaines, A.

    1987-11-01

    The W.R. Grace Chemical Division plant in Lake Charles, LA had to stop producing catalysts for the oil refining industry whenever a piping system for 98% sulfuric acid developed a leak. Gaskets of a nonasbestos material were being used between the flanges of the steel pipe lined with TFE or polypropylene. The flange bolts were kept tight, but the gaskets usually failed to maintain a leaktight seal with the acid at 60 psi for more than a few weeks or months. The acid lines had to be drained before the faulty gasket could be replaced, and production downtime would range from one to three hours. In July 1986, the plant decided to try a chemical resistant gasket of Teflon molded and bonded to a core of Shore A 65-66 durometer EPDM rubber in the acid lines. The resilient gasket also has patented double convex rings on both faces for optimum sealing with only one-eighth the bolt tightening torque commonly required with flat-faced gaskets. The low sealing force requirement prolongs the life of the gasket, eliminates plastic cold flow at the flange of lined steel pipe, and avoids stresses that can damage thermoplastic and fiberglass piping systems. The gasket has a temperature range of {minus}4 to 210{degree}F and is available in 1/2 through 12 inch sizes that conform to ANSI B16.1 flange dimensions. Alternative gasket materials are Kynar PVDF-bonded EPDM and EPDM without a fluoropolymer laminate. The Teflon-bonded EPDM gaskets eliminated unscheduled catalyst production downtime due to leakage from the sulfuric acid piping system. The plant maintains an inventory of the low torque gasket, but has never had to replace any that have been in service since July 1986.

  14. High-Temperature Oxidation Behavior of Iridium-Rhenium Alloys

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.

    1995-01-01

    The life-limiting mechanism for radiation-cooled rockets made from iridium-coated rhenium (Ir/Re) is the diffusion of Re into the Ir layer and the subsequent oxidation of the resulting Ir-Re alloy from the inner surface. In a previous study, a life model for Ir/Re rockets was developed. It incorporated Ir-Re diffusion and oxidation data to predict chamber lifetimes as a function of temperature and oxygen partial pressure. Oxidation testing at 1540 deg C suggested that a 20-wt percent Re concentration at the inner wall surface should be established as the failure criterion. The present study was performed to better define Ir-oxidation behavior as a function of Re concentration and to supplement the data base for the life model. Samples ranging from pure Ir to Ir-40 wt percent Re (Ir-40Re) were tested at 1500 deg C, in two different oxygen environments. There were indications that the oxidation rate of the Ir-Re alloy increased significantly when it went from a single-phase solid solution to a two-phase mixture, as was suggested in previous work. However, because of testing anomalies in this study, there were not enough dependable oxidation data to definitively raise the Ir/Re rocket failure criterion from 20-wt percent Re to a Re concentration corresponding to entry into the two-phase region.

  15. Iridium/Rhenium Parts For Rocket Engines

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.; Harding, John T.; Wooten, John R.

    1991-01-01

    Oxidation/corrosion of metals at high temperatures primary life-limiting mechanism of parts in rocket engines. Combination of metals greatly increases operating temperature and longevity of these parts. Consists of two transition-element metals - iridium and rhenium - that melt at extremely high temperatures. Maximum operating temperature increased to 2,200 degrees C from 1,400 degrees C. Increases operating lifetimes of small rocket engines by more than factor of 10. Possible to make hotter-operating, longer-lasting components for turbines and other heat engines.

  16. Iridium/Rhenium Parts For Rocket Engines

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.; Harding, John T.; Wooten, John R.

    1991-01-01

    Oxidation/corrosion of metals at high temperatures primary life-limiting mechanism of parts in rocket engines. Combination of metals greatly increases operating temperature and longevity of these parts. Consists of two transition-element metals - iridium and rhenium - that melt at extremely high temperatures. Maximum operating temperature increased to 2,200 degrees C from 1,400 degrees C. Increases operating lifetimes of small rocket engines by more than factor of 10. Possible to make hotter-operating, longer-lasting components for turbines and other heat engines.

  17. Thin graphite bipolar plate with associated gaskets and carbon cloth flow-field for use in an ionomer membrane fuel cell

    DOEpatents

    Marchetti, George A.

    2003-01-03

    The present invention comprises a thin graphite plate with associated gaskets and pieces of carbon cloth that comprise a flow-field. The plate, gaskets and flow-field comprise a "plate and gasket assembly" for use in an ionomer membrane fuel cell, fuel cell stack or battery.

  18. High Resolution Laser Spectroscopy of Rhenium Carbide

    NASA Astrophysics Data System (ADS)

    Adam, Allan G.; Hall, Ryan M.; Linton, Colan; Tokaryk, Dennis

    2014-06-01

    The first spectroscopic study of rhenium carbide, ReC, has been performed using both low and high resolution techniques to collect rotationally resolved electronic spectra from 420 to 500nm. Laser-induced fluorescence (LIF), and dispersed fluorescence (DF) techniques were employed. ReC was formed in our laser ablation molecular jet apparatus by ablating a rhenium target rod in the presence of 1% methane in helium. The low resolution spectrum identified four bands of an electronic system belonging to ReC, three of which have been studied so far. Extensive hyperfine structure composed of six hyperfine components was observed in the high resolution spectrum, as well as a clear distinction between the 187ReC and 185ReC isotopologues. The data seems consistent with a ^4Π - ^4Σ- transition, as was predicted before experimentation. Dispersed fluorescence spectra allowed us to determine the ground state vibrational frequency (ωe"=994.4 ± 0.3 wn), and to identify a low-lying electronically excited state at Te"=1118.4 ± 0.4 wn with a vibrational frequency of ωe"=984 ± 2 wn. Personal communication, F. Grein, University of New Brunswick

  19. Development of chemically vapor deposited rhenium emitters of (0001) preferred crystal orientation

    NASA Technical Reports Server (NTRS)

    Yang, L.; Hudson, R. G.

    1973-01-01

    Rhenium thermionic emitters were prepared by the pyrolysis of rhenium chlorides formed by the chlorination of rhenium pellets. The impurity contents, microstructures, degrees of (0001) preferred crystal orientation, and vacuum electron work functions of these emitters were determined as a function of deposition parameters, such as substrate temperature, rhenium pellet temperature and chlorine flow rate. A correlation between vacuum electron work function and degree of (0001) preferred crystal orientation was established. Conditions for depositing porosity-free rhenium emitters of high vacuum electron work functions were defined. Finally, three cylindrical rhenium emitters were prepared under the optimum deposition conditions.

  20. Rhenium labeled peptides and antibodies for cancer therapy. CRADA final report

    SciTech Connect

    Knapp, Jr., F. F.; Rhodes, B. A.

    1996-08-12

    This CRADA involved development of optimal methods for attachment of rhenium radioisotopes to antibodies and peptides which can be used for cancer treatment. Rhenium-186 and the tungsten-188/rhenium-188 generators were provided from ORNL to RhoMed for peptide labeling studies. The rhenium-186 and carrier-free rhenium-188 were then used to optimize the labeling of various small peptides....A system has been developed at ORNL which provides the rhenium-188 radioisotope, which has excellent therapeutic properties for cancer treatment.

  1. Toward hypoxia-selective rhenium and technetium tricarbonyl complexes.

    PubMed

    North, Andrea J; Hayne, David J; Schieber, Christine; Price, Katherine; White, Anthony R; Crouch, Peter J; Rigopoulos, Angela; O'Keefe, Graeme J; Tochon-Danguy, Henri; Scott, Andrew M; White, Jonathan M; Ackermann, Uwe; Donnelly, Paul S

    2015-10-05

    With the aim of preparing hypoxia-selective imaging and therapeutic agents, technetium(I) and rhenium(I) tricarbonyl complexes with pyridylhydrazone, dipyridylamine, and pyridylaminocarboxylate ligands containing nitrobenzyl or nitroimidazole functional groups have been prepared. The rhenium tricarbonyl complexes were synthesized with short reaction times using microwave irradiation. Rhenium tricarbonyl complexes with deprotonated p-nitrophenyl pyridylhydrazone ligands are luminescent, and this has been used to track their uptake in HeLa cells using confocal fluorescent microscopy. Selected rhenium tricarbonyl complexes displayed higher uptake in hypoxic cells when compared to normoxic cells. A (99m)Tc tricarbonyl complex with a dipyridylamine ligand bearing a nitroimidazole functional group is stable in human serum and was shown to localize in a human renal cell carcinoma (RCC; SK-RC-52) tumor in a mouse.

  2. Rhenium(VII) Catalysis of Prins Cyclization Reactions

    PubMed Central

    Tadpetch, Kwanruthai; Rychnovsky, Scott D.

    2009-01-01

    The rhenium(VII) complex O3ReOSiPh3 are particularly effective catalyst for Prins cyclizations using aromatic and α,β-unsaturated aldehydes. The reaction conditions are mild and the highly substituted 4-hydroxy tetrahydropyran products are formed stereoselectively. Rhenium(VII) complexes appear to spontaneously form esters with alcohols and to directly activate electron rich alcohols for solvolysis. Re2O7 and perrhenic acid were equally effective in catalyzing these cyclizations. PMID:18816133

  3. Resistance heating of the gasket in a gem-anvil high pressure cell

    NASA Astrophysics Data System (ADS)

    Balzaretti, N. M.; Gonzalez, E. J.; Piermarini, G. J.; Russell, T. P.

    1999-11-01

    Resistance heating of the gasket strip in a gem-anvil high pressure cell was successful in obtaining sample temperatures up to 1100 °C, under pressures up to 4.0 GPa. The heating capabilities, as well as the mechanical and chemical stability, of several different gasket strips (two Ni-based alloys, Ta, Pt/Rh, and a Re/Mo alloy) with different design shapes, and two different single-crystal anvil materials (diamond and cubic zirconia) were investigated. Two gasket-strip designs were found to provide optimum uniform heating conditions while decreasing the required current needed to achieve 1100 °C. Two anvil systems were investigated to reduce the temperature increase of the pressure cell body. Cubic zirconia anvils reduced the cell-body temperature to 100 °C at sample temperatures up to 1100 °C. However, zirconia anvils often failed during heating and almost always failed during cooling. Diamond anvils with cubic zirconia mounting plates also permitted temperatures up to 1100 °C to be reached without anvil failure. However, the cell-body temperature increased to 300 °C. A sealed vacuum-type chamber was employed to eliminate the problem with gasket and anvil oxidation. The optimized operating parameters reported here provide a routine method for high temperature-high pressure studies. The method was used to densify and sinter nanosize amorphous silicon nitride and γ-alumina powders at high temperatures and high pressures.

  4. Assessment of airborne asbestos exposure during the servicing and handling of automobile asbestos-containing gaskets.

    PubMed

    Blake, Charles L; Dotson, G Scott; Harbison, Raymond D

    2006-07-01

    Five test sessions were conducted to assess asbestos exposure during the removal or installation of asbestos-containing gaskets on vehicles. All testing took place within an operative automotive repair facility involving passenger cars and a pickup truck ranging in vintage from late 1960s through 1970s. A professional mechanic performed all shop work including engine disassembly and reassembly, gasket manipulation and parts cleaning. Bulk sample analysis of removed gaskets through polarized light microscopy (PLM) revealed asbestos fiber concentrations ranging between 0 and 75%. Personal and area air samples were collected and analyzed using National Institute of Occupational Safety Health (NIOSH) methods 7400 [phase contrast microscopy (PCM)] and 7402 [transmission electron microscopy (TEM)]. Among all air samples collected, approximately 21% (n = 11) contained chrysotile fibers. The mean PCM and phase contrast microscopy equivalent (PCME) 8-h time weighted average (TWA) concentrations for these samples were 0.0031 fibers/cubic centimeters (f/cc) and 0.0017 f/cc, respectively. Based on these findings, automobile mechanics who worked with asbestos-containing gaskets may have been exposed to concentrations of airborne asbestos concentrations approximately 100 times lower than the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 0.1 f/cc.

  5. The next step in chemical propulsion: Oxide-iridium/rhenium combustion chambers

    SciTech Connect

    Fortini, Arthur J.; Tuffias, Robert H.

    1999-01-22

    Chemical propulsion systems are currently limited by materials issues. Until recently, the state-of-the-art material for liquid propellant combustion chambers was silicide-coated niobium. However, combustion chamber performance demands have exceeded the capabilities of this material system, requiring development of better materials. The iridium/rhenium combustion chamber, comprising a rhenium structural shell with an iridium inner liner for oxidation protection, represents the current state of the art in high-performance, high temperature, long-life propulsion systems using nitrogen tetroxide/monomethyl hydrazine propellant. However, oxygen/hydrogen (O{sub 2}/H{sub 2}) and new 'green' monopropellants under development to replace hydrazine will be significantly more oxidizing at operating temperature. For these more highly aggressive combustion environments, Ultramet has shown that substantial additional life can be obtained by lining the interior of the combustion chamber with a refractory metal oxide, which functions as a thermal and gas diffusion barrier and provides dramatically increased oxidation resistance. Ultramet has fabricated numerous 22-N (5-lb{sub f}) thrust chambers with this oxide-iridium/rhenium architecture that have been hot-fire tested at NASA Lewis Research Center in O{sub 2}/H{sub 2} propellant at mixture ratios of 6 and 16, with steady-state exterior wall temperatures ranging from 2433 to 2899 K, comprising the most severe temperature and oxidizing conditions ever utilized. Of the seven chambers tested to date, three failed due to facility problems, and two never failed. The best-performing chamber was hot-fired for 13,595 seconds (227 minutes; 3.8 hours) and showed no visible signs of degradation. Additional chambers are being fabricated for future testing.

  6. The next step in chemical propulsion: Oxide-iridium/rhenium combustion chambers

    NASA Astrophysics Data System (ADS)

    Fortini, Arthur J.; Tuffias, Robert H.

    1999-01-01

    Chemical propulsion systems are currently limited by materials issues. Until recently, the state-of-the-art material for liquid propellant combustion chambers was silicide-coated niobium. However, combustion chamber performance demands have exceeded the capabilities of this material system, requiring development of better materials. The iridium/rhenium combustion chamber, comprising a rhenium structural shell with an iridium inner liner for oxidation protection, represents the current state of the art in high-performance, high temperature, long-life propulsion systems using nitrogen tetroxide/monomethyl hydrazine propellant. However, oxygen/hydrogen (O2/H2) and new ``green'' monopropellants under development to replace hydrazine will be significantly more oxidizing at operating temperature. For these more highly aggressive combustion environments, Ultramet has shown that substantial additional life can be obtained by lining the interior of the combustion chamber with a refractory metal oxide, which functions as a thermal and gas diffusion barrier and provides dramatically increased oxidation resistance. Ultramet has fabricated numerous 22-N (5-lbf) thrust chambers with this oxide-iridium/rhenium architecture that have been hot-fire tested at NASA Lewis Research Center in O2/H2 propellant at mixture ratios of 6 and 16, with steady-state exterior wall temperatures ranging from 2433 to 2899 K, comprising the most severe temperature and oxidizing conditions ever utilized. Of the seven chambers tested to date, three failed due to facility problems, and two never failed. The best-performing chamber was hot-fired for 13,595 seconds (227 minutes; 3.8 hours) and showed no visible signs of degradation. Additional chambers are being fabricated for future testing.

  7. 40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable to...

  8. 40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable to...

  9. 40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable to...

  10. 40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable to...

  11. 40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable to...

  12. Determination of rhenium in molybdenite by X-ray fluorescence. A combined chemical-spectrometric technique

    USGS Publications Warehouse

    Solt, M.W.; Wahlberg, J.S.; Myers, A.T.

    1969-01-01

    Rhenium in molybdenite is separated from molybdenum by distillation of rhenium heptoxide from a perchloric-sulphuric acid mixture. It is concentrated by precipitation of the sulphide and then determined by X-ray fluorescence. From 3 to 1000 ??g of rhenium can be measured with a precision generally within 2%. The procedure tolerates larger amounts of molybdenum than the usual colorimetric methods. ?? 1969.

  13. Room-Temperature Tensile Behavior of Oriented Tungsten Single Crystals with Rhenium in Dilute Solid Solution

    DTIC Science & Technology

    1966-01-01

    SINGLE CRYSTALS WITH RHENIUM IN DILUTE SOLID SOLUTION Sby M. Garfinkle Lewis Research Center Cleveland, Ohio 20060516196 NATIONAL AERONAUTICS AND...WITH RHENIUM IN DILUTE SOLID SOLUTION By M. Garfinkle Lewis Research Center Cleveland, Ohio NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by...ORIENTED TUNGSTEN SINGLE CRYSTALS WITH RHENIUM IN DILUTE SOLID SOLUTION * by M. Garfinkle Lewis Research Center SUMMARY Tungsten single crystals

  14. Properties and degradation of the gasket component of a proton exchange membrane fuel cell--a review.

    PubMed

    Basuli, Utpal; Jose, Jobin; Lee, Ran Hee; Yoo, Yong Hwan; Jeong, Kwang-Un; Ahn, Jou-Hyeon; Nah, Changwoon

    2012-10-01

    Proton exchange membrane (PEM) fuel cell stack requires gaskets and seals in each cell to keep the reactant gases within their respective regions. Gasket performance is integral to the successful long-term operation of a fuel cell stack. This review focuses on properties, performance and degradation mechanisms of the different polymer gasket materials used in PEM fuel cell under normal operating conditions. The different degradation mechanisms and their corresponding representative mitigation strategies are also presented here. Summary of various properties of elastomers and their advantages and disadvantages in fuel cell'environment are presented. By considering the level of chemical degradation, mechanical properties and cost effectiveness, it can be proposed that EPDM is one of the best choices for gasket material in PEM fuel cell. Finally, the challenges that remain in using rubber component as in PEM fuel cell, as well as the prospects for exploiting them in the future are discussed.

  15. A tale of two fractals: The Hofstadter butterfly and the integral Apollonian gaskets

    NASA Astrophysics Data System (ADS)

    Satija, Indubala I.

    2016-11-01

    This paper unveils a mapping between a quantum fractal that describes a physical phenomena, and an abstract geometrical fractal. The quantum fractal is the Hofstadter butterfly discovered in 1976 in an iconic condensed matter problem of electrons moving in a two-dimensional lattice in a transverse magnetic field. The geometric fractal is the integer Apollonian gasket characterized in terms of a 300 BC problem of mutually tangent circles. Both of these fractals are made up of integers. In the Hofstadter butterfly, these integers encode the topological quantum numbers of quantum Hall conductivity. In the Apollonian gaskets an infinite number of mutually tangent circles are nested inside each other, where each circle has integer curvature. The mapping between these two fractals reveals a hidden D3 symmetry embedded in the kaleidoscopic images that describe the asymptotic scaling properties of the butterfly. This paper also serves as a mini review of these fractals, emphasizing their hierarchical aspects in terms of Farey fractions.

  16. Effect of rhenium on the structure and properties of the weld metal of a molybdenum alloy

    NASA Technical Reports Server (NTRS)

    Dyachenko, V. V.; Morozov, B. P.; Tylkina, M. A.; Savitskiy, Y. M.; Nikishanov, V. V.

    1984-01-01

    The structure and properties of welds made in molybdenum alloy VM-1 as a function of rhenium concentrations in the weld metal were studied. Rhenium was introduced into the weld using rhenium wire and tape or wires of Mo-47Re and Mo-52Re alloys. The properties of the weld metal were studied by means of metallographic techniques, electron microscopy, X-ray analysis, and autoradiography. The plasticity of the weld metal sharply was found to increase with increasing concentration of rhenium up to 50%. During welding, a decarburization process was observed which was more pronounced at higher concentrations of rhenium.

  17. “Pop-slide” patterning: Rapid fabrication of microstructured PDMS gasket slides for biological applications

    PubMed Central

    Ramji, Ramesh; Khan, Nafeesa T; Muñoz-Rojas, Andrés; Miller-Jensen, Kathryn

    2015-01-01

    We describe a “pop-slide” patterning approach to easily produce thin film microstructures on the surface of glass with varying feature sizes (3 μm – 250 μm) and aspect ratios (0.066 – 3) within 45 minutes. This low cost method does not require specialized equipment while allowing us to produce micro structured gasket layers for sandwich assays and could be readily applied to many biological applications. PMID:26949529

  18. Z-Pinch Wire-Electrode Contact Resistance Studies Using Weighted and Soft Metal Gasket Contacts*

    NASA Astrophysics Data System (ADS)

    Gomez, M. R.; Zier, J. C.; Thurtell, A. F.; French, D. M.; Gilgenbach, R. M.; Tang, W.; Lau, Y. Y.

    2008-11-01

    The contact made between z-pinch wires and electrodes has a significant effect on both the energy deposited in the wires and the uniformity of the expansion profile of the wires. We have shown that using soft metal gaskets can improve wire-electrode contact significantly over typical weighted contacts. Images of wire expansion profile and wire plasma emission will be presented for single and double wire shots on a 16 kA, 100 kV 4-stage Marx bank with 150 ns risetime. Bench resistance measurements for aluminum, stainless steel, and tungsten wires with diameters ranging from 7.5 um to 30 um will be presented. These measurements utilized both soft metal gasket contacts (gaskets include: indium, silver, aluminum, tin, and lead) and double-ended wire weight contacts (weights ranged from 0.4 g to 1.9 g). *This research was supported by U. S. DoE through Sandia National Laboratories award document numbers 240985, 768225, 790791 and 805234 to the University of Michigan. MRG supported by NNSA Fellowship and JCZ supported by NPSC Fellowship sponsored by Sandia National Labs.

  19. A different 'spin' on rhenium chemistry. synthetic approaches and perspectives of 17-electron rhenium complexes.

    PubMed

    Zobi, Fabio

    2010-01-01

    Transition metal complexes of rhenium and technetium find wide application in nuclear medicine and the chemistry of these elements is still the focus of intense research efforts. For therapeutic and diagnostic applications, currently much attention is dedicated to the development of new targeting strategies aimed at appending the metal complexes to biological vectors (e.g. a peptide) for a site-specific delivery of the radionuclides. Advancements in radiopharmacy, however, will not only arise from the development of new targeted strategies but also from the exploration of the chemistry of these elements in their unusual oxidation states. In this respect the even number oxidation states of Re and Tc (i.e. +II, +IV and +VI) are relatively poorly understood. In particular, stable and substitutionally labile mononuclear 17-electron species of the elements (+II, d(5)) are a rarely encountered class of complexes. In this review we present our recent developments in the field of rhenium (II) chemistry with emphasis on the novel synthetic strategies we have recently introduced. We will also describe how the unique chemical and electronic properties of Re(II)-based complexes may provide a potentially new approach for applications in inorganic medicinal chemistry.

  20. Rhenium-catalysed hydroboration of aldehydes and aldimines.

    PubMed

    Arévalo, Rebeca; Vogels, Christopher M; MacNeil, Gregory A; Riera, Lucía; Pérez, Julio; Westcott, Stephen A

    2017-06-28

    The first examples for the rhenium-catalysed hydroboration of aldehydes, ketones and aldimines, including heteroaromatic quinoline, are reported herein. Reactions are remarkably chemoselective and tolerant of several functional groups. A wide array of rhenium complexes were efficient pre-catalysts for these hydroborations, including new low-valent complexes of the formula [Re(N-N)(CO)3(L)]X (N-N = bipy derivative, L = labile ligand/solvent, and X = [BAr(F)4](-) and [B(3,5-di-tBu-cat)2](-)), which have been characterized fully including an X-ray diffraction study for [Re(bipy)(CO)3(quin)][BAr(F)4] (2). A new silver spiroboronate ester Ag[B(3,5-di-tBu-cat)2](NCCH3)3 (3) was prepared and characterized fully, including an X-ray diffraction study, and used to make one of the new rhenium complexes.

  1. Application of Technetium and Rhenium in Nuclear Medicine

    NASA Astrophysics Data System (ADS)

    Alberto, Roger

    2012-06-01

    Technetium and Rhenium are the two lower elements in the manganese triad. Whereas rhenium is known as an important part of high resistance alloys, technetium is mostly known as a cumbersome product of nuclear fission. It is less known that its metastable isotope 99mTc is of utmost importance in nuclear medicine diagnosis. The technical application of elemental rhenium is currently complemented by investigations of its isotope 188Re, which could play a central role in the future for internal, targeted radiotherapy. This article will briefly describe the basic principles behind diagnostic methods with radionuclides for molecular imaging, review the 99mTc-based radiopharmaceuticals currently in clinical routine and focus on the chemical challenges and current developments towards improved, radiolabeled compounds for diagnosis and therapy in nuclear medicine.

  2. Mechanical properties of electron-beam-melted molybdenum and dilute molybdenum-rhenium alloys

    NASA Technical Reports Server (NTRS)

    Klopp, W. D.; Witzke, W. R.

    1972-01-01

    A study of molybdenum and three dilute molybdenum-rhenium alloys was undertaken to determine the effects of rhenium on the low temperature ductility and other mechanical properties of molybdenum. Alloys containing 3.9, 5.9, and 7.7 atomic percent rhenium exhibited lower ductile-brittle transition temperatures than did the unalloyed molybdenum. The maximum improvement in the annealed condition was observed for molybdenum - 7.7 rhenium, which had a ductile-brittle transition temperature approximately 200 C (360 F) lower than that for unalloyed molybdenum. Rhenium additions also increased the low and high temperature tensile strengths and the high temperature creep strength of molybdenum. The mechanical behavior of dilute molybdenum-rhenium alloys is similar to that observed for dilute tungsten-rhenium alloys.

  3. Mechanistic Study of Oxygen Atom Transfer Catalyzed by Rhenium Compounds

    SciTech Connect

    Shan, Xiaopeng

    2003-01-01

    Two ionic and one neutral methyl(oxo)rhenium(V) compounds were synthesized and structurally characterized. They were compared in reactivity towards the ligands triphenylphosphane, pyridines, pyridine N-oxides. Assistance from Broensted bases was found on ligand displacement of ionic rhenium compounds as well as nucleophile assistance on oxidation of all compounds. From the kinetic data, crystal structures, and an analysis of the intermediates, a structural formula of PicH+3- and mechanisms of ligand displacement and oxidation were proposed.

  4. Fabrication and characterization of heparin-grafted poly-L-lactic acid-chitosan core-shell nanofibers scaffold for vascular gasket.

    PubMed

    Wang, Ting; Ji, Xuyuan; Jin, Lin; Feng, Zhangqi; Wu, Jinghang; Zheng, Jie; Wang, Hongyin; Xu, Zhe-Wu; Guo, Lingling; He, Nongyue

    2013-05-01

    Electrospun nanofibers were widely studied to be applied as potential materials for tissue engineering. A new technology to make poly-l-lactic acid/chitosan core/shell nanofibers from heterologous solution by coaxial electrospinning technique was designed for vascular gasket. Chitosan surface was cross-linked by genipin and modified by heparin. Different ratios of PLA/CS in heterologous solution were studied to optimize the surface morphology of fibers. Clean core-shell structures formed with a PLA/CS ratio at 1:3. Superior biocompatibility and mechanical properties were obtained by optimizing the core-shell structure morphology and surface cross-linking of chitosan. UE7T-13 cells grew well on the core-shell structure fibers as indicated by methylthiazolyldiphenyl-tetrazolium bromide (MTT) results and scanning electron microscopy (SEM) images. Compared with the pure PLA fiber meshes and commercial vascular patch, PLA/CS core-shell fibers had better mechanical strength. The elastic modulus was as high as 117.18 MPa, even though the yield stress of the fibers was lower than that of the commercial vascular patch. Attachment of red blood cell on the fibers was evaluated by blood anticoagulation experiments and in vitro blood flow experiments. The activated partial thromboplastin time (APTT) and prothrombin time (PT) value from PLA/CS nanofibers were significantly longer than that of pure PLA fibers. SEM images indicated there were hardly any red blood cells attached to the fibers with chitosan coating and heparin modification. This type of fiber mesh could potentially be used as vascular gasket.

  5. Development and Evaluation of Rhenium-188-labeled Radioactive Stents for Restenosis Therapy and Development of Strategies for Radiolabeling Brachytherapy Sources with Palladium-103 CRADA FINAL REPORT

    SciTech Connect

    Knapp, F. F.

    1998-06-01

    This project involved collaboration between InnerDyne, Inc., and radiopharmaceutical research programs at ORNL and Brookhaven National Laboratory (BNL) which explored new strategies for the development and animal testing of radioactive rhenium-188-labeled implantable stent sources for the treatment of coronary restenosis after angioplasty and the development of chemical species radiolabeled with the palladium-103 radioisotope for the treatment of cancer. Rhenium-l 88 was made available for these studies from radioactive decay of tungsten-188 produced in the ORNL High Flux Isotope Reactor (HFIR). Stent activation and coating technology was developed and provided by InnerDyne, Inc., and stent radiolabeling technology and animal studies were conducted by InnerDyne staff in conjunction with investigators at BNL. Collaborative studies in animals were supported at sites by InnerDyne, Inc. New chemical methods for attaching the palladium-103 radioisotope to bifunctional chelate technologies were developed by investigators at ORNL.

  6. Resonance region measurements of dysprosium and rhenium

    NASA Astrophysics Data System (ADS)

    Leinweber, Gregory; Block, Robert C.; Epping, Brian E.; Barry, Devin P.; Rapp, Michael J.; Danon, Yaron; Donovan, Timothy J.; Landsberger, Sheldon; Burke, John A.; Bishop, Mary C.; Youmans, Amanda; Kim, Guinyun N.; Kang, yeong-rok; Lee, Man Woo; Drindak, Noel J.

    2017-09-01

    Neutron capture and transmission measurements have been performed, and resonance parameter analysis has been completed for dysprosium, Dy, and rhenium, Re. The 60 MeV electron accelerator at RPI Gaerttner LINAC Center produced neutrons in the thermal and epithermal energy regions for these measurements. Transmission measurements were made using 6Li glass scintillation detectors. The neutron capture measurements were made with a 16-segment NaI multiplicity detector. The detectors for all experiments were located at ≈25 m except for thermal transmission, which was done at ≈15 m. The dysprosium samples included one highly enriched 164Dy metal, 6 liquid solutions of enriched 164Dy, two natural Dy metals. The Re samples were natural metals. Their capture yield normalizations were corrected for their high gamma attenuation. The multi-level R-matrix Bayesian computer code SAMMY was used to extract the resonance parameters from the data. 164Dy resonance data were analyzed up to 550 eV, other Dy isotopes up to 17 eV, and Re resonance data up to 1 keV. Uncertainties due to resolution function, flight path, burst width, sample thickness, normalization, background, and zero time were estimated and propagated using SAMMY. An additional check of sample-to-sample consistency is presented as an estimate of uncertainty. The thermal total cross sections and neutron capture resonance integrals of 164Dy and Re were determined from the resonance parameters. The NJOY and INTER codes were used to process and integrate the cross sections. Plots of the data, fits, and calculations using ENDF/B-VII.1 resonance parameters are presented.

  7. Rhenium Disulfide Depletion-Load Inverter

    NASA Astrophysics Data System (ADS)

    McClellan, Connor; Corbet, Chris; Rai, Amritesh; Movva, Hema C. P.; Tutuc, Emanuel; Banerjee, Sanjay K.

    2015-03-01

    Many semiconducting Transition Metal Dichalcogenide (TMD) materials have been effectively used to create Field-Effect Transistor (FET) devices but have yet to be used in logic designs. We constructed a depletion-load voltage inverter using ultrathin layers of Rhenium Disulfide (ReS2) as the semiconducting channel. This ReS2 inverter was fabricated on a single micromechanically-exfoliated flake of ReS2. Electron beam lithography and physical vapor deposition were used to construct Cr/Au electrical contacts, an Alumina top-gate dielectric, and metal top-gate electrodes. By using both low (Aluminum) and high (Palladium) work-function metals as two separate top-gates on a single ReS2 flake, we create a dual-gated depletion mode (D-mode) and enhancement mode (E-mode) FETs in series. Both FETs displayed current saturation in the output characteristics as a result of the FET ``pinch-off'' mechanism and On/Off current ratios of 105. Field-effect mobilities of 23 and 17 cm2V-1s-1 and subthreshold swings of 97 and 551 mV/decade were calculated for the E-mode and D-mode FETs, respectively. With a supply voltage of 1V, at low/negative input voltages the inverter output was at a high logic state of 900 mV. Conversely with high/positive input voltages, the inverter output was at a low logic state of 500 mV. The inversion of the input signal demonstrates the potential for using ReS2 in future integrated circuit designs and the versatility of depletion-load logic devices for TMD research. NRI SWAN Center and ARL STTR Program.

  8. Solution and diffusion of hydrogen isotopes in tungsten-rhenium alloy

    NASA Astrophysics Data System (ADS)

    Ren, Fei; Yin, Wen; Yu, Quanzhi; Jia, Xuejun; Zhao, Zongfang; Wang, Baotian

    2017-08-01

    Rhenium is one of the main transmutation elements forming in tungsten under neutron irradiation. Therefore, it is essential to understand the influence of rhenium impurity on hydrogen isotopes retention in tungsten. First-principle calculations were used to study the properties of hydrogen solution and diffusion in perfect tungsten-rhenium lattice. The interstitial hydrogen still prefers the tetrahedral site in presence of rhenium, and rhenium atom cannot act directly as a trapping site of hydrogen. The presence of rhenium in tungsten raises the solution energy and the real normal modes of vibration on the ground state and the transition state, compared to hydrogen in pure tungsten. Without zero point energy corrections, the presence of rhenium decreases slightly the migration barrier. It is found that although the solution energy would tend to increase slightly with the rising of the concentration of rhenium, but which does not influence noticeably the solution energy of hydrogen in tungsten-rhenium alloy. The solubility and diffusion coefficient of hydrogen in perfect tungsten and tungsten-rhenium alloy have been estimated, according to Sievert's law and harmonic transition state theory. The results show the solubility of hydrogen in tungsten agrees well the experimental data, and the presence of Re would decrease the solubility and increase the diffusivity for the perfect crystals.

  9. Platinum-, rhenium-, indium-containing catalysts for conversion of hydrocarbons

    SciTech Connect

    Antos, G.J.; Wang, L.

    1986-12-16

    A process is described for the catalytic reforming of naphtha-boiling range charge stock at reforming conditions with a catalytic composite comprising: (a) a refractory inorganic oxide; (b) a first uniform dispersion of a platinum component and a rhenium component; (c) a second dispersion of an indium component thereover; (d) a halogen component; and (e) a sulfur component.

  10. Methane conversation on the oxidized platinum-rhenium-alumina crystals

    SciTech Connect

    Abasov, S.I.; Babaeva, F.A.; Dadashev, B.A.

    1995-05-01

    The conversion of methane on the oxidized platinum-rhenium-alumina catalysts is studied. The catalytic dehydrocyclohexamerization to benzene is found to proceed on the catalyst after its partial reduction with methane and subsequent coke deposition on the catalyst surface. The effect of both the framework oxygen and coke deposition on the dehydrocyclohexamerization process is discussed.

  11. Rhenium(I)-based Double-heterostranded Helicates.

    PubMed

    Saxena, Priya; Shankar, Bhaskaran; Sathyanarayana, Arruri; Prabusankar, Ganesan; Sathiyendiran, Malaichamy

    2015-01-01

    Rhenium(I)-based supramolecular coordination complexes were obtained using Re2(CO)10, (2-hydroxyphenyl)benzimidazole-derived bis-chelating N∩O donors and a benzimidazolyl-derived ditopic monodentate N-donor possessing Troger's base spacer in a one-pot approach.

  12. Discovery of tantalum, rhenium, osmium, and iridium isotopes

    SciTech Connect

    Robinson, R.; Thoennessen, M.

    2012-09-15

    Currently, thirty-eight tantalum, thirty-eight rhenium, thirty-nine osmium, and thirty-eight iridium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  13. Speciation of Rhenium in Chloride Melts: Spectroscopic and Electrochemical Study

    NASA Astrophysics Data System (ADS)

    Danilov, Danil A.; Volkovich, Vladimir A.; Vasin, Boris D.; Aleksandrov, Denis E.; Polovov, Ilya B.; Griffiths, Trevor R.

    2008-06-01

    Speciation of rhenium in high-temperature alkali chloride-based melts was studied using electronic absorption and IR spectroscopy of molten salts and diffuse reflectance spectroscopy of quenched melts. Rhenium was added to the melts by anodic dissolution of the metal (at anodic current densities of 0.005 - 0.05 A/cm2), by reacting Re and ReO2 with Cl2 and HCl, and by dissolving K2[ReCl6]. The melts included 3LiCl-2KCl and NaCl-2CsCl eutectics, an NaCl-KCl equimolar mixture, and pure NaCl, KCl and CsCl between 450 and 850 ◦C. Rhenium was present in the melts as Re(IV) hexachloro-ions, [ReCl6]2-; no evidence of species containing rhenium in oxidation states below four was obtained. The kinetics of [ReCl6]2- disproportionation in molten alkali chlorides were investigated, and the IR spectra of [ReO4]- ions in molten CsCl-CsI and CsI were measured for the first time.

  14. Gasket seal closure for extended endonasal endoscopic skull base surgery: efficacy in a large case series.

    PubMed

    Garcia-Navarro, Victor; Anand, Vijay K; Schwartz, Theodore H

    2013-11-01

    To assess long-term efficacy of the gasket seal, a method for watertight closure of the cranial base using autologous fascia lata held in place by a rigid buttress, in a large case series. A prospectively acquired database of all endonasal endoscopic surgeries performed over a 5-year period at Weill Cornell Medical College starting in September 2005 was reviewed. The gasket seal was used in 46 consecutive patients. Mean age was 53 years (range 7-83 years). All patients had extensive intracranial disease with a significant intraoperative cerebrospinal fluid (CSF) leak. Pathology included craniopharyngioma (39.1%), meningioma (23.9%), and pituitary adenoma (17.4%). After a mean follow-up of 28 months (range 3-63 months), two (4.3%) patients had a postoperative CSF leak. Excluding the patients with adenomas, the CSF leak rate was 5.2% (2 of 38 patients). One leak was controlled with reoperation, and the other was stopped with a lumbar drain (LD). The significance of pathology, type of approach, exposure of the ventricular system, use of fat graft, use of nasoseptal (NS) flap, and use of lumbar drain (LD) was examined, and none of these were significant predictors of postoperative CSF leak. Gasket seal closure is a reliable long-term effective method for achieving watertight closure of the cranial base. It can be used in association with an intracranial fat graft, NS flap, LD, and tissue sealants. In this series, none of these other factors were significant predictors of postoperative CSF leak. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Supported rhenium complexes: almost uniform rhenium tricarbonyls synthesized from CH3Re(CO)5 and HY zeolite.

    PubMed

    Lobo-Lapidus, Rodrigo J; Gates, Bruce C

    2010-11-02

    Supported rhenium complexes were prepared from CH(3)Re(CO)(5) and dealuminated HY zeolite or NaY zeolite, each with a Si/Al atomic ratio of 30. The samples were characterized with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies. EXAFS data characterizing the sample formed by the reaction of CH(3)Re(CO)(5) with dealuminated HY zeolite show that the rhenium complexes were bonded to the zeolite frame, incorporating, on average, three carbonyl ligands per Re atom (as shown by Re-C and multiple-scattering Re-O EXAFS contributions). The IR spectra, consistent with this result, show that the supported rhenium carbonyls were bonded near aluminum sites of the zeolite, as shown by the decrease in intensity of the IR bands characterizing the acidic silanol groups resulting from the reaction of the rhenium carbonyl with the zeolite. This supported metal complex was characterized by narrow peaks in the ν(CO) region of the IR spectrum, indicating highly uniform species. In contrast, the species formed from CH(3)Re(CO)(5) on NaY zeolite lost fewer carbonyl ligands than those formed on HY zeolite and were significantly less uniform, as indicated by the greater breadth of the ν(CO) bands in the IR spectra. The results show the importance of zeolite H(+) sites for the formation of uniform supported rhenium carbonyls from CH(3)Re(CO)(5); the formation of such uniform complexes did not occur on the NaY zeolite.

  16. Uptake and efflux of rhenium in cells exposed to rhenium diseleno-ether and tissue distribution of rhenium and selenium after rhenium diseleno-ether treatment in mice.

    PubMed

    Collery, Philippe; Bastian, Gérard; Santoni, François; Mohsen, Ahmed; Wei, Ming; Collery, Thomas; Tomas, Alain; Desmaele, Didier; D'Angelo, Jean

    2014-04-01

    We proposed a new water-soluble rhenium diseleno-ether compound (with one atom of Re and two atoms of Se) and investigated the uptake of Re into the nucleus of malignant cells in culture exposed to the compound for 48 h and its efflux from the nucleus after a post-exposure period of 48 h, as DNA is the main target of Re. We also studied the distribution of both Re and Se in the main organs after an oral administration of 10 or 40 mg/kg Re diseleno-ether to mice for four weeks, five days-a-week. Re and Se concentrations were assayed by inductively coupled plasma mass spectrometry (ICP-MS). Statistical analysis was performed using the Wilcoxon signed-rank test, comparing two related groups. We observed that Re was well incorporated into the nucleus of malignant cells in the most sensitive cells MCF-7, derived from human breast cancer, and that there was no efflux of Re. In contrast, in MCF-7 resistant cells (MCF-7 Mdr and MCF-7 R), A549 and HeLa cells, there was significant efflux of Re from the nucleus after the wash-out period. In mice, an important and dose-dependent uptake of both Re and Se was observed in the liver, with lower concentrations in kidneys. The lowest concentrations were observed in blood, lung, spleen and bones. There was a significant increase of Re concentrations in the blood, liver and kidney in mice treated with Re diseleno-ether at the dose of 40 mg/kg/24 h versus those treated at the dose of 10 mg/kg/24 h. There was a significant increase of Se concentrations in all tissues with the dose of Re diseleno-ether of 10 mg/kg/24 h versus controls, and a significant increase in the liver in mice treated with dose of Re diseleno-ether of 40 mg/kg/24h versus those treated with 10 mg/kg/24 h. We are the first to demonstrate that a compound combining Re and Se in a single molecule, is able to deliver Re and Se to the organism via an oral route, for cancer treatment.

  17. Development and testing of high temperature coatings for the Integrated Solar Upper Stage thermal energy storage system

    NASA Astrophysics Data System (ADS)

    Miles, Barry J.

    1997-01-01

    Key components within the Integrated Solar Upper Stage (ISUS) bimodal system must be able to operate at temperatures as high as 2500 K within both hard vacuum and hot hydrogen environments. Graphite has been selected as the primary thermal energy storage device for ISUS system level and engine ground demonstration testing. The selection of graphite dictated the need for development and testing of high temperature coatings to identify a candidate that can maintain structural integrity at elevated temperatures, be compatible with graphite, and mitigate carbon loss from the graphite. This paper presents the methodology and test results that led to selection of rhenium as the coating material. Vacuum and hydrogen flow tests conducted between 2000 K and 2600 K on rhenium coated graphite coupons indicate mass loss reductions as much as one order of magnitude lower than unprotected graphite under similar temperatures, pressures, hydrogen flowrates, and exposure durations. The durability of rhenium coatings up to 0.381 mm thick was also demonstrated.

  18. Exposure to airborne asbestos during removal and installation of gaskets and packings: a review of published and unpublished studies.

    PubMed

    Madl, Amy K; Clark, Katherine; Paustenbach, Dennis J

    2007-01-01

    In recent years, questions have been raised about the health risks to persons who have been occupationally exposed to asbestos-containing gaskets and packing materials used in pipes, valves, and machinery (pumps, autos, etc.). Up until the late 1970s, these materials were widely used throughout industrial and maritime operations, refineries, chemical plants, naval ships, and energy plants. Seven simulation studies and four work-site industrial hygiene studies of industrial and maritime settings involving the collection of more than 300 air samples were evaluated to determine the likely airborne fiber concentrations to which a worker may have been exposed while working with encapsulated asbestos-containing gaskets and packing materials. Each study was evaluated for the representativeness of work practices, analytical methods, sample size, and potential for asbestos contamination (e.g., insulation on valves or pipes used in the study). Specific activities evaluated included the removal and installation of gaskets and packings, flange cleaning, and gasket formation. In all but one of the studies relating to the replacement of gaskets and packing using hand-held tools, the short-term average exposures were less than the current 30-min OSHA excursion limit of 1 fiber per cubic centimeter (f/cc) and all of the long-term average exposures were less than the current 8-h permissible exposure limit time-weighted average (PEL-TWA) of 0.1 f/cc. The weight of evidence indicates that the use of hand tools and hand-operated power tools to remove or install gaskets or packing as performed by pipefitters or other tradesmen in nearly all plausible situations would not have produced airborne concentrations in excess of contemporaneous regulatory levels.

  19. DEVELOPMENT OF REMOTE HANFORD CONNECTOR GASKET REPLACEMENT TOOLING FOR THE SAVANNAH RIVER SITE'S DEFENSE WASTE PROCESSING FACILITY

    SciTech Connect

    Krementz, D

    2007-11-27

    The Savannah River Site's (SRS) Defense Waste Processing Facility (DWPF) requested development of tooling for remote replacement of gaskets in mechanical Hanford connectors. The facility has compressed air supply, two master-slave manipulators (MSM's) and a lightweight robotic arm for operation of the remote tools. The Savannah River National Laboratory (SRNL) developed and tested multiple tools to perform the gasket replacement tasks. Separate pneumatic snap-ring removal tools that use the connector skirt as a reaction surface were developed for removal of the snap ring and spent gasket on both vertical and horizontal Hanford connectors. A pneumatic tool that clamps and centers on the jumper pipe ID was developed to simultaneously install the new gasket and snap ring. A pneumatic snap-ring-loading tool was developed that compresses the snap ring and places it in a groove in the installation tool. All of the tools are located on a custom work table with a pneumatic valve station that directs compressed air to the desired tool and vents the tools as needed. The entire system has been successfully tested using MSM's to manipulate the various tools. Deployment of the entire system is expected during FY08. The Hanford connector gasket replacement tooling has been successfully tested using MSM's to manipulate the various tools. Nitric acid is used in many of the decontamination processes performed in the REDC, where the tooling will be deployed. Although most of the tool components were fabricated/purchased with nitric acid and radioactive service in mind, some of the prototype parts must be replaced with parts that are more compatible with nitric acid/radioactive service. Several modifications to the various tools are needed to facilitate maintenance and replacement of failed components. Development of installation tools for replacement of 1-inch, 2-inch and multi-hole gaskets is being considered. Deployment of the existing system in the DWPF REDC is expected during FY

  20. Testing the influence of various conditions on the migration of epoxidised soybean oil from polyvinylchloride gaskets.

    PubMed

    Hanušová, Kristýna; Rajchl, Aleš; Votavová, Lenka; Dobiáš, Jaroslav; Steiner, Ingrid

    2013-01-01

    Epoxidised soybean oil (ESBO) is widely used as a plasticiser and stabiliser mainly in food contact materials on the base of polyvinylchloride (PVC), especially in the gaskets of jar lids. PVC gaskets containing 10-37% of ESBO were prepared by the baking of PVC plastisols at various process temperatures (180-240°C) in the laboratory. ESBO migration into olive oil and 3% acetic acid was studied at various temperatures (4°C, 25°C, 40°C and 60°C) during a storage time up to 12 months. ESBO released into food simulants was transmethylated, derivatised and analysed by gas chromatography-mass spectrometry (GC/MS). The effect of food processing, i.e. pasteurisation (80°C and 100°C) and sterilisation (125°C) on ESBO migration was also evaluated. The results were critically assessed with respect to the test conditions of specific migration in accordance with the current European Union legislation (Regulation (EU) No. 10/2011). The levels of ESBO migration found confirmed that the test conditions (i.e. 40°C or 60°C, 10 days) representing contact in the worst foreseeable use scenario seem to be insufficient for the simulation of ESBO migration during long-term storage and thus do not provide satisfactory objective results.

  1. Rhenium and Molybdenum in Rivers and Estuaries.

    NASA Astrophysics Data System (ADS)

    Walker, B. D.; Peucker-Ehrenbrink, B.

    2004-12-01

    Due to their redox-sensitive nature, the geochemical cycles of Re and Mo are linked to the global organic carbon cycle. Reducing sediments constitute a globally important sink and weathering of organic-rich sediments is responsible for a large portion of the Re and - to a lesser extent - Mo flux to the oceans (Colodner et al., 1993; Jaffe et al., 2002). Riverine concentrations of Re and Mo are a function of the river basin lithology, but are also likely to be affected by anthropogenic contributions (Colodner et al., 1995). Current estimates of global natural riverine Re flux are restricted to single analyses of four major rivers, which characterize only 23%\\ of the global freshwater flux (Colodner et al., 1993). Annual variability of Re and Mo concentrations in rivers has not been studied. A single study of Re concentrations along the salinity gradient of the Amazon shelf is suggestive of conservative mixing, but scatter in the data do not allow to exclude the possibility of Re addition in the low-salinity end of the profile (Colodner et al., 1993). Careful evaluation of samples from the Hudson River estuary using a variety of extraction techniques indicates that spike-sample equilibration was not fully achieved using commonly used methods. We have therefore developed a simple, clean and efficient method of extracting Re from filtered water samples. Our method utilizes syringe filtration, prolonged heating to achieve spike-sample equilibration, batch equilibration with TEVA resin, and extraction of Re and Mo using syringe filtration. Rhenium concentrations in the Hudson, Housatonic and Connecticut rivers are 38 pM, 6.6 pM and 14 pM, respectively, much higher than the estimated global average of 2.1 pM (Colodner et al., 1993). Molybdenum concentrations are 4.6 nM, 5.5 nM, 7.8 nM, respectively. These rivers drain basins of Precambrian basement as well as predominantly Paleozoic sediments and have been substantially urbanized. Data for a salinity profile along the

  2. Migration of rhenium and osmium interstitials in tungsten

    NASA Astrophysics Data System (ADS)

    Suzudo, Tomoaki; Yamaguchi, Masatake; Hasegawa, Akira

    2015-12-01

    Tungsten is expected to be a promising plasma-facing material for future fusion devices, but radiation-induced precipitation (RIP), which leads the material to hardening, is a concern at their practical use. One of the keys to accurate prediction of the emergence of RIP is migration of solute atoms, rhenium and osmium, that are produced by nuclear transmutation through irradiation. We conduct a series of numerical simulations using an atomic kinetic Monte Carlo method and investigate the migration of these solute atoms in the form of tungsten-rhenium and tungsten-osmium mixed dumbbells, considered to be the most efficient "carriers" of the solute atoms. We find that the low rotation energy barrier of these mixed dumbbells leading to three-dimensional migration greatly influences their diffusivities. The result also suggests that, although these dumbbells have three-dimensional motion, one cannot simply reduce their migration behavior to that of vacancy-like spherical objects.

  3. Necroptosis-Inducing Rhenium(V) Oxo Complexes

    PubMed Central

    Suntharalingam, Kogularamanan; Awuah, Samuel G.; Bruno, Peter M.; Johnstone, Timothy C.; Wang, Fang; Lin, Wei; Zheng, Yao-Rong; Page, Julia E.; Hemann, Michael T.; Lippard, Stephen J.

    2015-01-01

    Rhenium(V) oxo complexes of general formula [ReO(OMe)(N^N)Cl2], where N^N = 4,7-diphenyl-1,10-phenanthroline, 1, or 3,4,7,8-tetramethyl-1,10-phenanthroline, 2, effectively kill cancer cells by triggering necroptsosis, a non-apoptotic form of cell death. Both complexes evoke necrosome (RIP1-RIP3)-dependent intracellular ROS production and propidium iodide uptake. The complexes also induce mitochondrial membrane potential depletion, a possible downstream effect of ROS production. Apparently, 1 and 2 are the first rhenium complexes to evoke cellular events consistent with programmed necrosis in cancer cells. Furthermore, 1 and 2 display low acute toxicity in C57BL/6 mice and reasonable stability in fresh human blood. PMID:25698398

  4. Rhenium-catalyzed deoxydehydration of diols and polyols.

    PubMed

    Dethlefsen, Johannes R; Fristrup, Peter

    2015-03-01

    The substitution of platform chemicals of fossil origin by biomass-derived analogues requires the development of chemical transformations capable of reducing the very high oxygen content of biomass. One such reaction, which has received increasing attention within the past five years, is the rhenium-catalyzed deoxydehydration (DODH) of a vicinal diol into an alkene; this is a model system for abundant polyols like glycerol and sugar alcohols. The present contribution includes a review of early investigations of stoichiometric reactions involving rhenium, diols, and alkenes followed by a discussion of the various catalytic systems that have been developed with emphasis on the nature of the reductant, the substrate scope, and mechanistic investigations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Necroptosis-inducing rhenium(V) oxo complexes.

    PubMed

    Suntharalingam, Kogularamanan; Awuah, Samuel G; Bruno, Peter M; Johnstone, Timothy C; Wang, Fang; Lin, Wei; Zheng, Yao-Rong; Page, Julia E; Hemann, Michael T; Lippard, Stephen J

    2015-03-04

    Rhenium(V) oxo complexes of general formula [ReO(OMe)(N^N)Cl2], where N^N = 4,7-diphenyl-1,10-phenanthroline, 1, or 3,4,7,8-tetramethyl-1,10-phenanthroline, 2, effectively kill cancer cells by triggering necroptosis, a non-apoptotic form of cell death. Both complexes evoke necrosome (RIP1-RIP3)-dependent intracellular reactive oxygen species (ROS) production and propidium iodide uptake. The complexes also induce mitochondrial membrane potential depletion, a possible downstream effect of ROS production. Apparently, 1 and 2 are the first rhenium complexes to evoke cellular events consistent with programmed necrosis in cancer cells. Furthermore, 1 and 2 display low acute toxicity in C57BL/6 mice and reasonable stability in fresh human blood.

  6. Oxide Protective Coats for Ir/Re Rocket Combustion Chambers

    NASA Technical Reports Server (NTRS)

    Fortini, Arthur; Tuffias, Robert H.

    2003-01-01

    An improved material system has been developed for rocket engine combustion chambers for burning oxygen/ hydrogen mixtures or novel monopropellants, which are highly oxidizing at operating temperatures. The baseline for developing the improved material system is a prior iridium/rhenium system for chambers burning nitrogen tetroxide/monomethyl hydrazine mixtures, which are less oxidizing. The baseline combustion chamber comprises an outer layer of rhenium that provides structural support, plus an inner layer of iridium that acts as a barrier to oxidation of the rhenium. In the improved material system, the layer of iridium is thin and is coated with a thermal fatigue-resistant refractory oxide (specifically, hafnium oxide) that serves partly as a thermal barrier to decrease the temperature and thus the rate of oxidation of the rhenium. The oxide layer also acts as a barrier against the transport of oxidizing species to the surface of the iridium. Tests in which various oxygen/hydrogen mixtures were burned in iridium/rhenium combustion chambers lined with hafnium oxide showed that the operational lifetimes of combustion chambers of the improved material system are an order of magnitude greater than those of the baseline combustion chambers.

  7. Polarization-Resolved Raman Spectroscopy of Rhenium Disulfide

    NASA Astrophysics Data System (ADS)

    Chenet, Daniel; Aslan, Ozgur; Heinz, Tony; van der Zande, Arend; Hone, James

    2015-03-01

    Rhenium Disulfide (ReS2) is a layered semiconductor with each layer exhibiting a distorted 1T crystal structure. The reduced symmetry of the distorted 1T structure creates anisotropic optical and electrical properties that have been previously studied in bulk films. Herein, we demonstrate anisotropic behavior in its Raman spectra. We then correlate these vibrational modes with polarized absorption measurements in thin films in order to develop a versatile technique for determining the crystal orientation of anisotropic semiconducting thin films.

  8. Structure of rhenium-containing sodium borosilicate glass

    SciTech Connect

    Goel, Ashutosh; McCloy, John S.; Windisch, Charles F.; Riley, Brian J.; Schweiger, Michael J.; Rodriguez, Carmen P.; Ferreira, Jose M.

    2013-03-01

    A series of sodium borosilicate glasses were synthesized with increasing fractions of KReO4 or Re2O7, to 10000 ppm (1 mass%) target Re in glass, to assess the effects of large concentrations of rhenium on glass structure and to estimate the solubility of technetium, a radioactive component in typical low active waste nuclear waste glasses. Magic angle spinning nuclear magnetic resonance (MAS-NMR), Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy were performed to characterize the glasses as a function of Re source additions. In general, silicon was found coordinated in a mixture of Q2 and Q3 structural units, while Al was 4-coordinated and B was largely 3-coordinate and partially 4-coordinated. The rhenium source did not appear to have significant effects on the glass structure. Thus, at the up to the concentrations that remain in dissolved in glass, ~3000 ppm Re by mass maximum. , the Re appeared to be neither a glass-former nor a strong glass modifier., Rhenium likely exists in isolated ReO4- anions in the interstices of the glass network, as evidenced by the polarized Raman spectrum of the Re glass in the absence of sulfate. Analogous to SO42-¬ in similar glasses, ReO4- is likely a network modifier and forms alkali salt phases on the surface and in the bulk glass above solubility.

  9. CVD Rhenium Engines for Solar-Thermal Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Williams, Brian E.; Fortini, Arthur J.; Tuffias, Robert H.; Duffy, Andrew J.; Tucker, Stephen P.

    1999-01-01

    Solar-thermal upper-stage propulsion systems have the potential to provide specific impulse approaching 900 seconds, with 760 seconds already demonstrated in ground testing. Such performance levels offer a 100% increase in payload capability compared to state-of-the-art chemical upper-stage systems, at lower cost. Although alternatives such as electric propulsion offer even greater performance, the 6- to 18- month orbital transfer time is a far greater deviation from the state of the art than the one to two months required for solar propulsion. Rhenium metal is the only material that is capable of withstanding the predicted thermal, mechanical, and chemical environment of a solar-thermal propulsion device. Chemical vapor deposition (CVD) is the most well-established and cost-effective process for the fabrication of complex rhenium structures. CVD rhenium engines have been successfully constructed for the Air Force ISUS program (bimodal thrust/electricity) and the NASA Shooting Star program (thrust only), as well as under an Air Force SBIR project (thrust only). The bimodal engine represents a more long-term and versatile approach to solar-thermal propulsion, while the thrust-only engines provide a potentially lower weight/lower cost and more near-term replacement for current upper-stage propulsion systems.

  10. Prototype Rhenium Component for Stirling Engine Power Conversion

    NASA Astrophysics Data System (ADS)

    Leonhardt, Todd; Ritzert, Frank

    2005-02-01

    The Stirling engine power conversion concept is a candidate to provide electrical power for deep space missions. A key element for qualifying potential flight hardware is the long-term durability assessment for critical hot section components of the power converter. One such critical component is the power converter heater head, which is a high-temperature pressure vessel that transfers heat to the working gas medium of the converter. Rhenium is a candidate material for the heater head application because of its high melting point (3453 K), high elastic modulus (420 GPa), high yield and ultimate tensile strengths at both ambient and elevated temperatures, excellent ductility, and exceptional creep properties. Rhenium is also attractive due to the potential of near-net-shape (NNS) manufacturing techniques that allow components to be produced using less material, which lowers the overall cost of the component. The objective of this research was to demonstrate the manufacturing method using rhenium for this high-temperature power conversion application to provide space power system designers with generally applicable technology for future applications.

  11. CVD Rhenium Engines for Solar-Thermal Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Williams, Brian E.; Fortini, Arthur J.; Tuffias, Robert H.; Duffy, Andrew J.; Tucker, Stephen P.

    1999-01-01

    Solar-thermal upper-stage propulsion systems have the potential to provide specific impulse approaching 900 seconds, with 760 seconds already demonstrated in ground testing. Such performance levels offer a 100% increase in payload capability compared to state-of-the-art chemical upper-stage systems, at lower cost. Although alternatives such as electric propulsion offer even greater performance, the 6- to 18- month orbital transfer time is a far greater deviation from the state of the art than the one to two months required for solar propulsion. Rhenium metal is the only material that is capable of withstanding the predicted thermal, mechanical, and chemical environment of a solar-thermal propulsion device. Chemical vapor deposition (CVD) is the most well-established and cost-effective process for the fabrication of complex rhenium structures. CVD rhenium engines have been successfully constructed for the Air Force ISUS program (bimodal thrust/electricity) and the NASA Shooting Star program (thrust only), as well as under an Air Force SBIR project (thrust only). The bimodal engine represents a more long-term and versatile approach to solar-thermal propulsion, while the thrust-only engines provide a potentially lower weight/lower cost and more near-term replacement for current upper-stage propulsion systems.

  12. [X-ray fluorescence spectrometric determination of high rhenium content in rhenium-tungsten alloys used in traveling wave tube].

    PubMed

    Bao, Sheng-xiang; Wang, Shou-xu; Ma, Li-li; Zhao, Deng-hua; Fan, Rong-kui; Li, Jian

    2005-03-01

    The matrix effect, spectral overlap and background were investigated for X-ray fluorescence (XRF) spectrometric determination of rhenium content according to the analysis requirement of rhenium-tungsten alloys, a key material used in traveling wave tube. The reason for causing the calibration curve nonlinear was explained theoretically when binary ratio technique of XRF was used. Both theoretical and experimental results show that linear calibration curve can be obtained if the curve is plotted by Re% vs. Re Lalpha X-ray intensity instead of binary ratio technique. The method is rapid and accurate and the results obtained in this work are in good agreement with those of chemical analysis. The method has been successfully applied to product quality control.

  13. enantio-Enriched CPL-active helicene–bipyridine–rhenium complexes†

    PubMed Central

    Saleh, Nidal; Srebro, Monika; Reynaldo, Thibault; Vanthuyne, Nicolas; Toupet, Loïc; Chang, Victoria Y.; Muller, Gilles; Gareth Williams, J. A.; Roussel, Christian

    2016-01-01

    The incorporation of a rhenium atom within an extended helical π-conjugated bi-pyridine system impacts the chiroptical and photophysical properties of the resulting neutral or cationic complexes, leading to the first examples of rhenium-based phosphors that exhibit circularly polarized luminescence. PMID:25643941

  14. enantio-Enriched CPL-active helicene-bipyridine-rhenium complexes.

    PubMed

    Saleh, Nidal; Srebro, Monika; Reynaldo, Thibault; Vanthuyne, Nicolas; Toupet, Loïc; Chang, Victoria Y; Muller, Gilles; Williams, J A Gareth; Roussel, Christian; Autschbach, Jochen; Crassous, Jeanne

    2015-03-04

    The incorporation of a rhenium atom within an extended helical π-conjugated bi-pyridine system impacts the chiroptical and photophysical properties of the resulting neutral or cationic complexes, leading to the first examples of rhenium-based phosphors that exhibit circularly polarized luminescence.

  15. Rhenium Complexes and Clusters Supported on c-Al2O3: Effects of Rhenium Oxidation State and Rhenium Cluster Size on Catalytic Activity for n-butane Hydrogenolysis

    SciTech Connect

    Lobo Lapidus, R.; Gates, B

    2009-01-01

    Supported metals prepared from H{sub 3}Re{sub 3}(CO){sub 12} on {gamma}-Al{sub 2}O{sub 3} were treated under conditions that led to various rhenium structures on the support and were tested as catalysts for n-butane conversion in the presence of H{sub 2} in a flow reactor at 533 K and 1 atm. After use, two samples were characterized by X-ray absorption edge positions of approximately 5.6 eV (relative to rhenium metal), indicating that the rhenium was cationic and essentially in the same average oxidation state in each. But the Re-Re coordination numbers found by extended X-ray absorption fine structure spectroscopy (2.2 and 5.1) show that the clusters in the two samples were significantly different in average nuclearity despite their indistinguishable rhenium oxidation states. Spectra of a third sample after catalysis indicate approximately Re{sub 3} clusters, on average, and an edge position of 4.5 eV. Thus, two samples contained clusters approximated as Re{sub 3} (on the basis of the Re-Re coordination number), on average, with different average rhenium oxidation states. The data allow resolution of the effects of rhenium oxidation state and cluster size, both of which affect the catalytic activity; larger clusters and a greater degree of reduction lead to increased activity.

  16. In vitro comparison of the antiproliferative effects of rhenium-186 and rhenium-188 on human aortic endothelial cells.

    PubMed

    Sauter, Alexander; Arthasana, Daniel; Dittmann, Helmut; Pritzkow, Maren; Wiesinger, Benjamin; Schmehl, Joerg; Brechtel, Klaus; Bantleon, Rüdiger; Claussen, Claus; Kehlbach, Rainer

    2011-08-01

    Rhenium-186 ((186)Re) and rhenium-188 ((188)Re) are promising radionuclides for the inhibition of restenosis after percutaneous transluminal angioplasty or other vascular interventions. Until now the maximal dose tolerance of endothelial cells has not been clearly known. To characterize the effects of local irradiation treatment, human aortic endothelial cells (ECs) were incubated with different doses of (186)Re and (188)Re. Two days after plating, ECs received treatment for a period of 5 days. The total radiation doses applied were 1, 4, 8, 16, and 32 Gy. On days 1, 3, 5, 7, and 12 after initial rhenium incubation, cell growth, clonogenic activity, cell-cycle distribution, and cytoskeletal architecture were evaluated. From the first day on, a dose-dependent growth inhibition was observed. Cumulative doses of ≥32 Gy caused a weak colony formation and significant alterations in the cytoskeletal architecture. An increased fraction of cells in G2/M phase was seen for cumulative radiation doses of ≥16 Gy. Interestingly, there were no significant differences between (186)Re and (188)Re. Even for low dose rates of β particles a dose-dependent proliferation inhibition of ECs is seen. Doses beyond 32 Gy alter the cytoskeletal architecture with possibly endothelial dysfunction and late thrombosis.

  17. Atom Probe Tomography Analysis of the Distribution of Rhenium in Nickel Alloys

    SciTech Connect

    Mottura, A.; Warnken, N; Miller, Michael K; Reed, R. C.; Finnis, M.

    2010-01-01

    Atom probe tomography (APT) is used to characterise the distributions of rhenium in a binary Ni-Re alloy and the nickel-based single-crystal CMSX-4 superalloy. A purpose-built algorithm is developed to quantify the size distribution of solute clusters, and applied to the APT datasets to critique the hypothesis that rhenium is prone to the formation of clusters in these systems. No evidence is found to indicate that rhenium forms solute clusters above the level expected from random fluctuations. In CMSX-4, enrichment of Re is detected in the matrix phase close to the matrix/precipitate ({gamma}/{gamma}{prime}) phase boundaries. Phase field modelling indicates that this is due to the migration of the {gamma}/{gamma}{prime} interface during cooling from the temperature of operation. Thus, neither clustering of rhenium nor interface enrichments can be the cause of the enhancement in high temperature mechanical properties conferred by rhenium alloying.

  18. Effect of rhenium addition on tungsten fuzz formation in helium plasmas

    NASA Astrophysics Data System (ADS)

    Khan, Aneeqa; De Temmerman, Gregory; Morgan, Thomas W.; Ward, Michael B.

    2016-06-01

    The effect of the addition of rhenium to tungsten on the formation of a nanostructure referred to as 'fuzz' when exposed to helium plasmas at fusion relevant ion fluxes was investigated in the Magnum and Pilot PSI devices at the FOM Institute DIFFER. The effect rhenium had on fuzz growth was seen to be dependent on time, temperature and flux. Initial fuzz growth was seen to be highly dependent on grain orientation, with rhenium having little effect. Once the fuzz was fully developed, the effect of grain orientation disappeared and the rhenium had an inhibiting effect on growth. This could be beneficial for inhibiting fuzz growth in a future fusion reactor, where transmutation of tungsten to rhenium is expected. It also appears that erosion or annealing of the fuzz is limiting growth of fuzz at higher temperatures in the range of ∼1340 °C.

  19. Thiphene hydrodesulfurization over rhenium surfaces: The effects of structure and adsorbates (C and S)

    SciTech Connect

    Bussell, M.E.; Somorjai, G.A. )

    1989-03-09

    Thiophene hydrodesulfurization (HDS) has been investigated over rhenium single crystals and polycrystalline foils and was found to be a structure-sensitive reaction over these surfaces. Rhenium single crystals are 1-6 times more active than molybdenum single crystals, which is in agreement with previous studies using rhenium disulfide and molybdenum disulfide catalysts. Adsorbed carbon and sulfur overlayers decrease the activity of the rhenium single crystals, suggesting that the catalyst surface remain free of strongly bound deposits of carbon and/or sulfur. The trend in HDS activity measured for the Re catalyst can be explained by considering the difference in coordination of the top layer rhenium atoms in the single-crystal surfaces.

  20. Nanosecond response ''gasket-type'' magnetic loop current monitor for relativistic electron beam current measurements.

    PubMed

    Copeland, R L; Adamski, J L; Doggett, W O; Morrow, D L; Bennett, W H

    1979-02-01

    A fast response magnetic loop current monitor has been developed to measure relativistic electron beam return currents. The monitor has a rise time of about a nanosecond and a high degree of symmetry with moderate sensitivity, variable from about 1 to 10 V/kA. This simple monitor, with a thickness of 0.254 mm or less, is thin enough to be placed between segments of return current path in the diode or drift tube regions, is insensitive to flashover, beam and plasma bombardment, and radiation effects, and measures net current, thus offering some advantages over conventional magnetic probes, since the main components are outside of the vacuum region. Design criteria, an equivalent circuit analysis, and typical calibration waveforms are presented. Experimental current measurements for a pinched electron beam diode configuration using both conventional magnetic probes and ''gasket-type''current monitors with the FX-75 relativistic electron beam accelerator are presented.

  1. Pressure concentrations due to plastic deformation of thin films or gaskets between anvils

    NASA Technical Reports Server (NTRS)

    Chan, K. S.; Huang, T. L.; Grzybowski, T. A.; Whetten, T. J.; Ruoff, A. L.

    1982-01-01

    Plastic deformation of either a sample or a gasket between diamond anvils leads to large pressure concentrations, i.e., the maximum pressure can be many times the average pressure. This behavior is discussed using elementary plasticity theory for the case where the pressures are sufficiently low that the yield stress can be assumed not to vary with pressure. It is then shown that the pressure concentration factor can be even much larger when the yield stress of the sample at the highest pressure is much greater than the yield stress at the lowest pressure. This is illustrated with solid xenon where it is shown that the assumption that Nelson and Ruoff made about the pressure distribution in their xenon samples is incorrect. The pressure distribution is shown to be much steeper than assumed. Thus, the pressure they observed electrical conduction in xenon was above 1 Mbar.

  2. Heat-resistant coatings for the high-pressure turbine blades of promising GTEs

    NASA Astrophysics Data System (ADS)

    Kablov, E. N.; Muboyadzhyan, S. A.

    2012-01-01

    Heat-resistant coatings are considered for the external surface of high-pressure turbine (HPT) single-crystal blades for promising gas turbine engines (GTEs) made from carbon-free nickel superalloys with rhenium or rhenium plus ruthenium. Nickel superalloys covered with heat-resistant coatings consisting of heat-resistant connecting layers and an external ZrO2-(7-8 wt %)Y2O3 ceramic layer are subjected to heat resistance and high-temperature tests. The test results are used to choose the heat-resistant layer that ensures the highest properties of a composition heat-resistant coating. The use of sequential chemical and physical deposition methods for coating layers is shown to be required to protect HPT blades in promising GTEs. Medium-frequency magnetron plasmachemical deposition of ceramic layers in heat-resistant coatings with a low thermal conductivity is found to be promising.

  3. The Marine Geochemistry of Rhenium, Iridium and Platinum

    DTIC Science & Technology

    1991-09-01

    waters a few centimeters below the interface was noted at other sites in the California borderlands by Shaw et al. (1990) and was interpreted as the...3000C. The hydrated dioxide (ReO 2-2H20) is readily formed by the action of various reducing agents on solutions of ReO 4-. Briscoe et al. (19?1) found...the hydrated dioxide. Rhenium heptasulfide (Re2S7) is obtained by saturation of 2 to 6 M HCI 9 solutions of ReO4 with H2S, although the precipitation is

  4. Ultra-small rhenium clusters supported on graphene.

    PubMed

    Miramontes, Orlando; Bonafé, Franco; Santiago, Ulises; Larios-Rodriguez, Eduardo; Velázquez-Salazar, Jesús J; Mariscal, Marcelo M; Yacaman, Miguel José

    2015-03-28

    The adsorption of very small rhenium clusters (2-13 atoms) supported on graphene was studied by high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM). The atomic structure of the clusters was fully resolved with the aid of density functional theory calculations and STEM simulations. It was found that octahedral and tetrahedral structures work as seeds to obtain more complex morphologies. Finally, a detailed analysis of the electronic structure suggested that a higher catalytic effect can be expected in Re clusters when adsorbed on graphene than in isolated ones.

  5. Preparation and properties of polytetrafluoroethylene impregnated with rhenium oxides

    NASA Technical Reports Server (NTRS)

    Leibecki, H. F.; Easter, R. W.

    1973-01-01

    The results of tests carried out to determine the properties of polytetrafluorethylene (PTFE) impregnated with rhenium oxides are presented. The tests included measurement of physical properties of the impregnated material and investigation of the effects of preparation process variables. Based on the latter tests a mechanism to describe the permeation process is postulated which identifies the rate controlling step to be diffusion of ReF6 molecules into the solid during the initial ReF6 soak. Physical property tests indicated that the electronic conductance is increased by many orders of magnitude while the desirable properties of the PTFE remain virtually unchanged.

  6. Molecular Engineering of Technetium and Rhenium Based Radiopharmaceuticals

    SciTech Connect

    Zubieta, J.

    2003-06-30

    The research was based on the observation that despite the extraordinarily rich coordination chemistry of technetium and rhenium and several notable successes in reagent design, the extensive investigations by numerous research groups on a variety of N{sub 2}S{sub 2} and N{sub 3}S donor type ligands and on HYNIC have revealed that the chemistries of these ligands with Tc and Re are rather complex, giving rise to considerable difficulties in the development of reliable procedures for the development of radiopharmaceutical reagents.

  7. Ultra-small rhenium clusters supported on graphene

    PubMed Central

    Miramontes, Orlando; Bonafé, Franco; Santiago, Ulises; Larios-Rodriguez, Eduardo; Velázquez-Salazar, Jesús J.; Mariscal, Marcelo M.; Yacaman, Miguel José

    2015-01-01

    The adsorption of very small rhenium clusters (2 – 13 atoms) supported on graphene was studied with high annular dark field - scanning transmission electron microscopy (HAADF-STEM). The atomic structure of the clusters was fully resolved with the aid of density functional calculations and STEM simulations. It was found that octahedral and tetrahedral structures work as seeds to obtain more complex morphologies. Finally, a detailed analysis of the electronic structure suggested that a higher catalytic effect can be expected in Re clusters when adsorbed on graphene than in isolated ones. PMID:25721176

  8. Functionalization of Rhenium Aryl Bonds by O-Atom Transfer

    SciTech Connect

    Bischof, Steven M.; Cheng, Mu-Jeng; Nielsen, Robert J.; Gunnoe, T. Brent; Goddard, William A.; Periana, Roy A.

    2011-03-29

    Aryltrioxorhenium (ArReO3) has been demonstrated to show rapid oxy-functionalization upon reaction with O-atom donors, YO, to selectively generate the corresponding phenols in near quantitative yields. 18O-Labeling experiments show that the oxygen in the products is exclusively from YO. DFT studies reveal a 10.7 kcal/mol barrier (Ar = Ph) for oxy-functionalization with H2O2 via a Baeyer-Villiger type mechanism involving nucleophilic attack of the aryl group on an electrophilic oxygen of YO coordinated to rhenium.

  9. Magnetron-Sputtered Amorphous Metallic Coatings

    NASA Technical Reports Server (NTRS)

    Thakoor, A. P.; Mehra, M.; Khanna, S. K.

    1985-01-01

    Amorphous coatings of refractory metal/metalloid-based alloys deposited by magnetron sputtering provide extraordinary hardness and wear resistance. Sputtering target fabricated by thoroughly mixing powders of tungsten, rhenium, and boron in stated proportions and pressing at 1,200 degrees C and 3,000 lb/in. to second power (21 MPa). Substrate lightly etched by sputtering before deposition, then maintained at bias of - 500 V during initial stages of film growth while target material sputtered onto it. Argon gas at pressure used as carrier gas for sputter deposition. Coatings dense, pinhole-free, extremely smooth, and significantly resistant to chemical corrosion in acidic and neutral aqueous environments.

  10. Clustering of transmutation elements tantalum, rhenium and osmium in tungsten in a fusion environment

    NASA Astrophysics Data System (ADS)

    You, Yu-Wei; Kong, Xiang-Shan; Wu, Xuebang; Liu, C. S.; Fang, Q. F.; Chen, J. L.; Luo, G.-N.

    2017-08-01

    The formation of transmutation solute-rich precipitates has been reported to seriously degrade the mechanical properties of tungsten in a fusion environment. However, the underlying mechanisms controlling the formation of the precipitates are still unknown. In this study, first-principles calculations are therefore performed to systemically determine the stable structures and binding energies of solute clusters in tungsten consisting of tantalum, rhenium and osmium atoms as well as irradiation-induced vacancies. These clusters are known to act as precursors for the formation of precipitates. We find that osmium can easily segregate to form clusters even in defect-free tungsten alloys, whereas extremely high tantalum and rhenium concentrations are required for the formation of clusters. Vacancies greatly facilitate the clustering of rhenium and osmium, while tantalum is an exception. The binding energies of vacancy-osmium clusters are found to be much higher than those of vacancy-tantalum and vacancy-rhenium clusters. Osmium is observed to strongly promote the formation of vacancy-rhenium clusters, while tantalum can suppress the formation of vacancy-rhenium and vacancy-osmium clusters. The local strain and electronic structure are analyzed to reveal the underlying mechanisms governing the cluster formation. Employing the law of mass action, we predict the evolution of the relative concentration of vacancy-rhenium clusters. This work presents a microscopic picture describing the nucleation and growth of solute clusters in tungsten alloys in a fusion reactor environment, and thereby explains recent experimental phenomena.

  11. High temperature coatings for gas turbines

    DOEpatents

    Zheng, Xiaoci Maggie

    2003-10-21

    Coating for high temperature gas turbine components that include a MCrAlX phase, and an aluminum-rich phase, significantly increase oxidation and cracking resistance of the components, thereby increasing their useful life and reducing operating costs. The aluminum-rich phase includes aluminum at a higher concentration than aluminum concentration in the MCrAlX alloy, and an aluminum diffusion-retarding composition, which may include cobalt, nickel, yttrium, zirconium, niobium, molybdenum, rhodium, cadmium, indium, cerium, iron, chromium, tantalum, silicon, boron, carbon, titanium, tungsten, rhenium, platinum, and combinations thereof, and particularly nickel and/or rhenium. The aluminum-rich phase may be derived from a particulate aluminum composite that has a core comprising aluminum and a shell comprising the aluminum diffusion-retarding composition.

  12. Compositional GC-FID analysis of the additives to PVC, focusing on the gaskets of lids for glass jars.

    PubMed

    Biedermann-Brem, Sandra; Biedermann, Maurus; Fiselier, Katell; Grob, Koni

    2005-12-01

    A gas chromatographic (FID) method is described which aims at the quantitative compositional analysis of the additives in plasticized PVC, particularly the plastisols used as gaskets for lids of glass jars. An extract of the PVC is analysed directly as well as after transesterification to ethyl esters. Transesterification enables the analysis of epoxidized soya bean and linseed oil (ESBO and ELO) as well as polyadipates. For most other additives, the shifts in the chromatogram resulting from transesterification is used to confirm the identifications made by direct analysis. In the gaskets of 69 lids from the European market used for packaging oily foods, a broad variety of plastisol compositions was found, many or possibly all of which do not comply with legal requirements. In 62% of these lids, ESBO was the principal plasticizer, whereas in 25% a phthalate had been used.

  13. Airborne asbestos exposures associated with gasket and packing replacement: a simulation study of flange and valve repair work and an assessment of exposure variables.

    PubMed

    Madl, Amy K; Devlin, Kathryn D; Perez, Angela L; Hollins, Dana M; Cowan, Dallas M; Scott, Paul K; White, Katherine; Cheng, Thales J; Henshaw, John L

    2015-02-01

    A simulation study was conducted to evaluate worker and area exposure to airborne asbestos associated with the replacement of asbestos-containing gaskets and packing materials from flanges and valves and assess the influence of several variables previously not investigated. Additionally, potential of take home exposures from clothing worn during the study was characterized. Our data showed that product type, ventilation type, gasket location, flange or bonnet size, number of flanges involved, surface characteristics, gasket surface adherence, and even activity type did not have a significant effect on worker exposures. Average worker asbestos exposures during flange gasket work (PCME=0.166 f/cc, 12-59 min) were similar to average worker asbestos exposures during valve overhaul work (PCME=0.165 f/cc, 7-76 min). Average 8-h TWA asbestos exposures were estimated to range from 0.010 to 0.062 f/cc. Handling clothes worn during gasket and packing replacement activities demonstrated exposures that were 0.71% (0.0009 f/cc 40-h TWA) of the airborne asbestos concentration experienced during the 5 days of the study. Despite the many variables considered in this study, exposures during gasket and packing replacement occur within a relatively narrow range, are below current and historical occupational exposure limits for asbestos, and are consistent with previously published data.

  14. Ambient aging of rhenium filaments used in thermal ionization mass spectrometry: Growth of oxo-rhenium crystallites and anti-aging strategies.

    PubMed

    Mannion, Joseph M; Wellons, Matthew S; Shick, Charles R; Fugate, Glenn A; Powell, Brian A; Husson, Scott M

    2017-01-01

    Degassing is a common preparation technique for rhenium filaments used for thermal ionization mass spectrometric analysis of actinides, including plutonium. Although optimization studies regarding degassing conditions have been reported, little work has been done to characterize filament aging after degassing. In this study, the effects of filament aging after degassing were explored to determine a "shelf-life" for degassed rhenium filaments, and methods to limit filament aging were investigated. Zone-refined rhenium filaments were degassed by resistance heating under high vacuum before exposure to ambient atmosphere for up to 2 months. After degassing the nucleation and preferential growth of oxo-rhenium crystallites on the surface of polycrystalline rhenium filaments was observed by atomic force microscopy and scanning electron microscopy (SEM). Compositional analysis of the crystallites was conducted using SEM-Raman spectroscopy and SEM energy dispersive X-ray spectroscopy, and grain orientation at the metal surface was investigated by electron back-scatter diffraction mapping. Spectra collected by SEM-Raman suggest crystallites are composed primarily of perrhenic acid. The relative extent of growth and crystallite morphology were found to be grain dependent and affected by the dissolution of carbon into filaments during annealing (often referred to as carbonization or carburization). Crystallites were observed to nucleate in region specific modes and grow over time through transfer of material from the surface. Factors most likely to affect the rates of crystallite growth include rhenium substrate properties such as grain size, orientation, levels of dissolved carbon, and relative abundance of defect sites; as well as environmental factors such as length of exposure to oxygen and relative humidity. Thin (∼180 nm) hydrophobic films of poly(vinylbenzyl chloride) were found to slow the growth of oxo-rhenium crystallites on the filament surfaces and may serve as

  15. The first finds of rhenium minerals in Karelia

    NASA Astrophysics Data System (ADS)

    Lavrov, O. B.; Kuleshevich, L. V.

    2010-05-01

    Rhenium is one of the rarest elements of the earth crust (abundance ratio 0.7 mg/t). In the Karelian region, Re and accompanying Os were discovered in a copper-molybdenum-porphyry ore formation, represented by the Lobash deposit, the Jalonvaara occurrences etc., and in a noble-metal-Cu-U-vanadium ore formation (Padma Group occurrences). Molybdenites from the above deposits are enriched in Re and Os (Lobash: 13-187 g/t Re, 0.4-6 g/t Os). So far, however, no rhenium minerals proper have been revealed in the Karelian deposits and occurrences of the above formations or elsewhere. As a result of the microprobe study of mineral assemblages of cupreous sandstones from the Voronov Bor deposit (bornite ore) and sulphide-copper-nickel ore from the Rybozero deposit, osmium-cupreous rheniite (Re, Cu, Os, Fe)1S2 that contains 56.53-60.25% Re, 4.61-10.99% Cu, 1.52-3.77% Os and up to 4.75% Fe was revealed and studied for the first time.

  16. Fluorescent rhenium-naphthalimide conjugates as cellular imaging agents.

    PubMed

    Langdon-Jones, Emily E; Symonds, Nadine O; Yates, Sara E; Hayes, Anthony J; Lloyd, David; Williams, Rebecca; Coles, Simon J; Horton, Peter N; Pope, Simon J A

    2014-04-07

    A range of biologically compatible, fluorescent rhenium-naphthalimide conjugates, based upon the rhenium fac-tricarbonyl core, has been synthesized. The fluorescent ligands are based upon a N-functionalized, 4-amino-derived 1,8-naphthalimide core and incorporate a dipicolyl amine binding unit to chelate Re(I); the structural variations accord to the nature of the alkylated imide with ethyl ester glycine (L(1)), 3-propanol (L(2)), diethylene glycol (L(3)), and benzyl alcohol (L(4)) variants. The species are fluorescent in the visible region between 505 and 537 nm through a naphthalimide-localized intramolecular charge transfer, with corresponding fluorescent lifetimes of up to 9.8 ns. The ligands and complexes were investigated for their potential as imaging agents for human osteoarthritic cells and protistan fish parasite Spironucleus vortens using confocal fluorescence microscopy. The results show that the specific nature of the naphthalimide structure serves to control the uptake and intracellular localization of these imaging agents. Significant differences were noted between the free ligands and complexes, with the Re(I) complex of L(2) showing hydrogenosomal localization in S. vortens.

  17. Redox reactivity of mononuclear and binuclear rhenium complexes

    SciTech Connect

    Holder, G.N.

    1988-01-01

    Six different classes of monomeric and dimeric rhenium complexes containing substituted nitriles, substituted pyridines, dithiocarbamates, and substituted phosphines as ligands were synthesized. Monomers had the general formula ReCl{sub 3} (NCR) (PPh{sub 3}){sub 2}, ReCl{sub 3}-(NCCH{sub 3})(P-(aryl-R){sub 3}){sub 2}, and ReOCl{sub 3} (P-(aryl-R){sub 3}){sub 2}. Dimers had the general formula Re{sub 2}Cl{sub 4} (dppm){sub 2} (NCR) and (Re{sub 2}Cl{sub 3}(dppm){sub 2}-(NCR){sub 2}){sup +} (dppm = bis(diphenylphosphino)methane) and Re{sub 2}O{sub 3}Cl{sub 4}-(py){sub 4}, where R was an alkyl or halogenated substituent chosen to systematically vary the donor-acceptor properties of the nitrile, pyridine, or phosphine ligand. The effects of this structural change on the function of the molecule was monitored both spectrally and electrochemically. Rate constants for addition of nitriles to the metal-metal bridged dimeric complex were found to vary linearly with the identity of the substitutent. Spectroscopic data followed these trends as well. The structure-function relationships derived from this work will aid in the design of future Technetium and Rhenium-based organ selective radioimaging agents.

  18. Compatibility of PWR gasket and packing materials and resins with organic amines

    SciTech Connect

    Keneshea, F.J.; Hobart, S.A. ); Camenzind, M.J. )

    1992-07-01

    The objectives of this testing program were two-fold: (1) to examine the compatibility of morpholine and five other amines with several synthetic polymeric materials useful for gaskets and seals in pressurized water reactor (PWR) secondary cycles and (2) to examine the potential chemical degradation of ion exchange (IX) resins by morpholine and ethanolamine. The screening of the polymeric materials in the amines was performed by heating small samples of the materials in the amines for one week to one month. Interaction of the amines with the materials was accelerated by testing at elevated temperatures and at high amine concentrations. Two materials (Kalrez and EPDM) that are potentially useful in high-temperature and high-pressure steam systems were tested in morpholine solutions in sealed bombs at 260{degrees}C (500{degrees}). After heating in the aqueous amine solutions, changes in weight were measured and the samples were visually examined for physical changes, such as swelling or cracking. Selected materials underwent testing for hardness, elongation, and tensile strength after heating in morpholine for one month. This document provides the results of this testing program.

  19. The role of coordination chemistry in the development of copper and rhenium radiopharmaceuticals.

    PubMed

    Donnelly, Paul S

    2011-02-07

    There are several isotopes of copper and rhenium that are of interest in the development of new molecular imaging or radiotherapeutic agents. This perspective article highlights the role of coordination chemistry in the design of copper and rhenium radiopharmaceuticals engineered to selectively target tissue of interest such as cancer cells or pathological features associated with Alzheimer's disease. The coordination chemistry of copper bis(thiosemicarbazone) derivatives and copper macrocyclic complexes is discussed in terms of their potential application as targeted positron emission tomography tracers for non-invasive diagnostic imaging. A range of rhenium complexes with different ligands with rhenium in different oxidation states are introduced and their potential to be translated to new radiotherapeutic agents discussed.

  20. Spectrophotometric catalytic determination of small amounts of rhenium in mineralized rocks and molybdenite

    USGS Publications Warehouse

    Simon, F.O.; Grimaldi, F.S.

    1962-01-01

    Rhenium is determined by spectrophotometry of the tellurium sol formed by the reduction of tellurate by stannous chloride under the catalytic influence of rhenium. A detailed investigation of the conditions for high sensitivity and stability at lowest concentration levels of rhenium is presented as well as the behavior of 26 ions. The method is applied to the determination of some tenths of 1 p.p.m. or more of rhenium in a 1-mg. aliquot of mineralized rocks, mixtures of molybdenite and rocks, and molybdenite concentrates. The practical quantity limit of detection is 2 ?? 10-10 gram of rhenium. Samples are decomposed with a mixture of CaO, CaCl2, and MgO. On leaching, most constituents of the sample are precipitated either as calcium salts or hydroxides, except for rhenium and a small amount of molybdenum which pass into the filtrate. Residual molybdenum is removed by extraction with 8-quinolinol in chloroform. Better than 95% recoveries are obtained with two fusions with flux.

  1. Separation of rhenium from molybdenum, tungsten, vanadium, platinum metals and other elements by reduction and solvent extraction.

    PubMed

    Yatirajam, V; Kakkar, L R

    1970-08-01

    Reduction in 1 M H(2)SO(4) with liquid zinc amalgam and extraction with isopentanol from 3M H(2)SO(4), separates rhenium from almost all the interfering elements of importance in rhenium determination. The small amounts of Mo, U, Fe and Ru still accompanying rhenium are removed by the thiocyanate-pentyl acetate or the oxine-chloroform extraction. The method is simple, rapid and of very wide applicability. It is particularly useful in the determination of rhenium in various alloys and tungsten-containing samples.

  2. Nitrogen concentration driving the hardness of rhenium nitrides

    PubMed Central

    Zhao, Zhonglong; Bao, Kuo; Li, Da; Duan, Defang; Tian, Fubo; Jin, Xilian; Chen, Changbo; Huang, Xiaoli; Liu, Bingbing; Cui, Tian

    2014-01-01

    The structures and properties of rhenium nitrides are studied with density function based first principle method. New candidate ground states or high-pressure phases at Re:N ratios of 3:2, 1:3, and 1:4 are identified via a series of evolutionary structure searches. We find that the 3D polyhedral stacking with strong covalent N-N and Re-N bonding could stabilize Re nitrides to form nitrogen rich phases, meanwhile, remarkably improve the mechanical performance than that of sub-nitrides, as Re3N, Re2N, and Re3N2. By evaluating the trends of the crystal configuration, electronic structure, elastic properties, and hardness as a function of the N concentration, we proves that the N content is the key factor affecting the metallicity and hardness of Re nitrides. PMID:24762713

  3. Flash heating in the diamond cell: melting curve of rhenium.

    PubMed

    Yang, Liuxiang; Karandikar, Amol; Boehler, Reinhard

    2012-06-01

    A new method for measuring melting temperatures in the laser-heated diamond cell is described. This method circumvents previous problems associated with the sample instability, thermal runaway, and chemical reactions. Samples were heated with a single, 20 milliseconds rectangular pulse from a fiber laser, monitoring their thermal response with a fast photomultiplier while measuring the steady state temperature with a CCD spectrometer. The samples were recovered and analyzed using scanning electron microscopy. Focused ion beam milling allowed to examine both the lateral and the vertical solid-liquid boundaries. Ambient pressure tests reproducibly yielded the known melting temperatures of rhenium and molybdenum. Melting of Re was measured to 50 GPa, a 5-fold extension of previous data. The refractory character of Re is drastically enhanced by pressure, in contrast to Mo.

  4. Rhenium-osmium isotope systematics of carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Walker, R. J.; Morgan, J. W.

    1989-01-01

    Rhenium and osmium concentrations and Os isotopic compositions of eight carbonaceous chondrites, one LL3 ordinary chondrite, and two iron meteorites were determined by resonance ionization mass spectrometry. Iron meteorite Re-187/Os-186 and Os-187/Os-186 ratios plot on the previously determined iron meteorite isochron, but most chondrite data plot 1 to 2 percent above this meteorite isochron. This suggests either that irons have significantly younger Re-Os closure ages than chondrites or that chondrites were formed from precursor materials with different chemical histories from the precursors of irons. Some samples of Semarkona (LL3) and Murray (C2M) meteorites plot 4 to 6 percent above the iron meteorite isochron, well above the field delineated by other chondrites. The isotopic composition of Semarkona could reflect assembly of isotopically heterogeneous components subsequent to 4.55 billion years ago or Os isotopic heterogeneities in the primordial solar nebular.

  5. Raman scattering from superhard rhenium diboride under high pressure

    SciTech Connect

    Xie, Miao; Winkler, Björn; Mao, Zhu; Kaner, Richard B.; Tolbert, Sarah H. E-mail: tolbert@chem.ucla.edu; Kavner, Abby E-mail: tolbert@chem.ucla.edu

    2014-01-06

    Lattice vibrational properties of superhard rhenium diboride (ReB{sub 2}) were examined up to 8 GPa in a diamond anvil cell using Raman spectroscopy techniques. Linear pressure coefficients and mode Grüneisen parameters are obtained. Good agreement is found between the experimental and theoretical calculated Grüneisen parameters. Examination of the calculated mode Grüneisen parameters reveals that both B-B and Re-B covalent bonds play a dominant role in supporting the applied load under pressure. A comparison of vibrations parallel and perpendicular to the c-axis indicates that bonds along the c-axis tend to take greater loads. Our results agree with observations of elastic lattice anisotropy obtained from both in situ X-ray diffraction measurements and ultrasonic resonance spectra.

  6. Organometallic Rhenium Complexes Divert Doxorubicin to the Mitochondria.

    PubMed

    Imstepf, Sebastian; Pierroz, Vanessa; Rubbiani, Riccardo; Felber, Michael; Fox, Thomas; Gasser, Gilles; Alberto, Roger

    2016-02-18

    Doxorubicin, a well-established chemotherapeutic agent, is known to accumulate in the cell nucleus. By using ICP-MS, we show that the conjugation of two small organometallic rhenium complexes to this structural motif results in a significant redirection of the conjugates from the nucleus to the mitochondria. Despite this relocation, the two bioconjugates display excellent toxicity toward HeLa cells. In addition, we carried out a preliminarily investigation of aspects of cytotoxicity and present evidence that the conjugates disrupt the mitochondrial membrane potential, are strong inhibitors of human Topoisomerase II, and induce apoptosis. Such derivatives may enhance the therapeutic index of the aggressive parent drug and overcome drug resistance by influencing nuclear and mitochondrial homeostasis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Electronic properties of rhenium and niobium doped tungsten disulfide monolayers

    NASA Astrophysics Data System (ADS)

    Cruz-Silva, Eduardo; McCreary, Amber; Lin, Zhong; Perea-Lopez, Nestor; Elias, Ana; Terrones, Humberto; Terrones, Mauricio

    2014-03-01

    Layered transition metal dichalcogenides (TMDs), have attracted great attention due to their electronic and optical properties. In particular, MoSand WSshow an indirect to direct electronic band gap transition when reduced to a monolayer, and display photoluminescence as a consequence. While there are proposed applications for MoSand WSas electronic and optoelectronic devices, control of their electronic properties needs to be reached before these applications can be scaled. In this sense, chemical doping has been recently shown to allow the modification of the electronic properties of MoSmonolayers by substitution of either transition metals or the chalcogen. Here we present a study of the electronic, magnetic, and chemical properties of doped WSmonolayers by performing ab initiocalculations. Substitution of tungsten atoms with either niobium or rhenium results in the formation of new states in the vicinity of the Fermi energy that allow to tailor the electronic band gaps, which results in different electronic and optical properties.

  8. Stereoisomeric complexes of technetium and rhenium with penicillamine

    SciTech Connect

    Johnson, D.L.; Fritzberg, A.R.; Eshima, D.; Kasina, S.; Bloedow, D.C.

    1984-01-01

    Very few direct comparisons exist between the coordination chemistry of technetium and rhenium. Such comparisons are useful in the synthesis and characterization of new Tc-99m radiopharmaceuticals and will likely be important in the development of radiotherapy agents based on Re-186 or -188. The authors report chemical studies on three stereoisomeric Tc-99 penicillamine complexes and their Re congeners as well as biological studies on the Tc-99m complexes. When Tc0/sub 4/-bar was reduced by SnCl/sub 2/ at pH 5.5 in the presence of D-penicillamine, a complex identical to the one characterized by a previous study as (D-pen)/sub 2/Tc0/sup -/ was formed. The same reaction using L-penacillamine gave the chromatographically identical enantiomer of the complex. When D,L-penicillamine was used, a second HPLC separable complex was formed in addition to the above mentioned enantiomers. Fast atom bombardment mass spectra showed the complexes to be isomeric. A proton NMR study of this second complex has shown it to be two enantiomeric forms of (D-pen)(L-pen)Tc0/sup -/ that interconvert rapidly in aqueous solution. The corresponding rhenium complexes were prepared by reduction of RE0/sub 4/-bar in 1 N HCl and were similarly characterized. The fluxional Tc complex racemizes with k/sub 1/=830 sec/sup -1/ at 25/sup 0//C and E/sub a/=13 kcal/mole while the Re complex racemizes much more slowly with k/sub 1/=285 sec/sup -1/ at 55/sup 0/ and E/sub a/=18.5 kcal/mole, consistent with the trend that second row transition metals undergo similar reactions at faster rates than their third row counterparts. Studies of the renal and hepatobiliary excretion of the Tc-99m complexes showed significant differences.

  9. Territory covered by N random walkers on fractal media: the Sierpinski gasket and the percolation aggregate.

    PubMed

    Acedo, L; Yuste, S B

    2001-01-01

    We address the problem of evaluating the number S(N)(t) of distinct sites visited up to time t by N noninteracting random walkers all starting from the same origin in fractal media. For a wide class of fractals (of which the percolation cluster at criticality and the Sierpinski gasket are typical examples) we propose, for large N and after the short-time compact regime, an asymptotic series for S(N)(t) analogous to that found for Euclidean media: S(N)(t) approximately S(N)(t)(1-Delta). Here S(N)(t) is the number of sites (volume) inside a hypersphere of radius L[ln(N)/c]1/v where L is the root-mean-square chemical displacement of a single random walker, and v and c determine how fast 1-Gamma(t)(l) (the probability that a given site at chemical distance l from the origin is visited by a single random walker by time t) decays for large values of l/L: 1-Gamma(t)(l) approximately exp[-c(l/L)(v)]. For the fractals considered in this paper, v=d(l)w/((d(l)w)-1), d(l)w being the chemical-diffusion exponent. The corrective term Delta is expressed as a series in ln(-n)(N)ln(m) ln(N) (with n> or =1 and 0< or =m< or =n), which is given explicitly up to n=2. This corrective term contributes substantially to the final value of S(N)(t) even for relatively large values of N.

  10. Initial Assessment of Environmental Barrier Coatings for the Prometheus Project

    SciTech Connect

    M. Frederick

    2005-12-15

    Depending upon final design and materials selections, a variety of engineering solutions may need to be considered to avoid chemical degradation of components in a notional space nuclear power plant (SNPP). Coatings are one engineered approach that was considered. A comprehensive review of protective coating technology for various space-reactor structural materials is presented, including refractory metal alloys [molybdenum (Mo), tungsten (W), rhenium (Re), tantalum (Ta), and niobium (Nb)], nickel (Ni)-base superalloys, and silicon carbide (Sic). A summary description of some common deposition techniques is included. A literature survey identified coatings based on silicides or iridium/rhenium as the primary methods for environmental protection of refractory metal alloys. Modified aluminide coatings have been identified for superalloys and multilayer ceramic coatings for protection of Sic. All reviewed research focused on protecting structural materials from extreme temperatures in highly oxidizing conditions. Thermodynamic analyses indicate that some of these coatings may not be protective in the high-temperature, impure-He environment expected in a Prometheus reactor system. Further research is proposed to determine extensibility of these coating materials to less-oxidizing or neutral environments.

  11. Tricarbonyl-rhenium complexes of a thiol-functionalized amphoteric poly(amidoamine).

    PubMed

    Donghi, Daniela; Maggioni, Daniela; D'Alfonso, Giuseppe; Amigoni, Federica; Ranucci, Elisabetta; Ferruti, Paolo; Manfredi, Amedea; Fenili, Fabio; Bisazza, Agnese; Cavalli, Roberta

    2009-12-14

    An amphoteric thiol-functionalized poly(amidoamine) nicknamed ISA23SH(10%) was synthesized. Rhenium complexes 1 and 2, containing 0.5 and 0.8 equiv of rhenium, respectively, were easily obtained by reacting ISA23SH(10%) with [Re(CO)(3)(H(2)O)(3)](CF(3)SO(3)) in aqueous solution at pH 5.5. Both ISA23SH(10%), and its rhenium complexes were soluble in water under physiological conditions. The resultant solutions were stable, even in the presence of cysteine. Rhenium chelation occurred through the S and N atoms of the cysteamine moiety, as demonstrated by (1)H, (13)C, and (15)N NMR spectroscopy. The diffusion coefficients and the hydrodynamic radii of ISA23SH(10%) and complex 1 were determined by pulsed gradient spin echo (PGSE) NMR experiments. The radius of the rhenium complexes 1 and 2 was always slightly larger than that of the parent polymer. TEM analysis showed that both complexes form spherical nanoparticles with narrow size distributions. Consistent results were obtained by dynamic light scattering. The observed sizes were in good agreement with those evaluated by PGSE. Preliminary in vitro and in vivo biological studies have been performed on complexes 1 and 2 as well as on the parent ISA23SH(10%). Neither hemolytic activity of the two rhenium complexes and the parent polymer, up to a concentration of 5 mg/mL, nor cytotoxic effects were observed on Hela cell after 48 h at a concentration of 100 ng/mL. In vivo toxicological tests showed that ISA23SH(10%) is highly biocompatible, with a maximum tolerated dose (MTD) of 500 mg/kg. No toxic side effects were apparent after the intravenous injection in mice of the two rhenium complexes in doses up to 20 mg/kg.

  12. Elasto-Plastic FEM Stress Analysis and Mechanical Characteristics of Pipe Flange Connections with Non-Asbestos Gaskets under Internal Pressure

    NASA Astrophysics Data System (ADS)

    Takagi, Yoshio; Omiya, Yuya; Kobayashi, Takashi; Sawa, Toshiyuki

    The effects of the nominal diameter of pipe flange connections with non-asbestos spiral wound gaskets(SWG) under internal pressure on the mechanical characteristics such as the contact gasket stress distribution which governs the sealing performance, the load factor and the hub stress of the connections were evaluated. The stresses in the connections with the nominal diameters from 3” to 24” under internal pressure are analyzed using the elasto-plastic(EP) FEM analysis taking account the hysteresis and non-linearity of deformation behavior of the non-asbestos SWG. As a result, it is found that the variations in the contact gasket stress distributions are substantial due to the flange rotation in the connections with the larger nominal diameter. Leakage tests were conducted to measure the axial bolt forces (the load factor) and the hub stress. The results obtained from the EP-FEM analyses are fairly consistent with the experimental results concerning the variation in the axial bolt forces (the load factor) and the hub stress. Using the obtained contact gasket stress distributions and the fundamental relationship between the amount of leakage and the contact gasket stress, the amount of the leakage of the connections is estimated. It is observed that the sealing performance of the connections with larger nominal diameter is worse than that of the connection with smaller nominal diameter because of the flange rotation. The estimated results are in a fairly good agreement with the measured results. The difference in the hub stress between the EP-FEM and ASME code is demonstrated and the differences in the load factor and the sealing performance of the connections are shown between the asbestos and non-asbestos gaskets.

  13. Containment of fluid samples in the hydrothermal diamond-anvil cell without the use of metal gaskets: Performance and advantages for in situ analysis

    USGS Publications Warehouse

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

    2008-01-01

    Metal gaskets (Re, Ir, Inconel, or stainless steel) normally used to contain fluid samples in the hydrothermal diamond-anvil cell (HDAC) are sometimes undesirable due to possible contamination and to gasket deformation at high pressures and temperatures resulting in nonisochoric behavior. Furthermore, in x-ray spectroscopic experiments, metal gaskets may attenuate the incident x-ray beam and emitted fluorescence x-rays, and the interaction of scattered radiation with the gasket may produce fluorescence that interferes with the x-ray spectrum of the sample. New arrangements and procedures were tested for the operation of the HDAC without using the metal gaskets. Distilled, de-ionized water was loaded into the sample chamber, a laser-milled recess 300 ??m in diameter and ???50 ??m deep centered in the 1.0 mm face of the lower diamond anvil, and sealed by pressing the top diamond anvil face directly against the lower one without a metal gasket in between. A maximum sample pressure of 202 MPa at 617 ??C was maintained for a duration of 10 min without evidence of leakage. A small change in fluid density was observed in one experiment where the sample was held at 266 MPa at 708 ??C for 10 min. The gasketless HDAC was also employed in x-ray absorption spectroscopy experiments, where, in addition to the sample chamber in the lower diamond, two grooves were milled at a 90?? angle to each other around the sample chamber to minimize the attenuation of incident and fluorescent x rays. With a minimum distance between the sample chamber and the grooves of 80 ??m, a pressure of 76 MPa at 500 ??C was maintained for 2 h with no change in the original fluid density. ?? 2008 American Institute of Physics.

  14. Effects of gasket on coupled plastic flow and strain-induced phase transformations under high pressure and large torsion in a rotational diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Feng, Biao; Levitas, Valery I.

    2016-01-01

    Combined plastic flow and strain-induced phase transformations (PTs) under high pressure in a sample within a gasket subjected to three dimensional compression and torsion in a rotational diamond anvil cell (RDAC) are studied using a finite element approach. The results are obtained for the weaker, equal-strength, and stronger high-pressure phases in comparison with low-pressure phases. It is found that, due to the strong gasket, the pressure in the sample is relatively homogenous and the geometry of the transformed zones is mostly determined by heterogeneity in plastic flow. For the equal-strength phases, the PT rate is higher than for the weaker and stronger high-pressure phases. For the weaker high-pressure phase, transformation softening induces material instability and leads to strain and PT localization. For the stronger high-pressure phase, the PT is suppressed by strain hardening during PT. The effect of the kinetic parameter k that scales the PT rate in the strain-controlled kinetic equation is also examined. In comparison with a traditional diamond anvil cell without torsion, the PT progress is much faster in RDAC under the same maximum pressure in the sample. Finally, the gasket size and strength effects are discussed. For a shorter and weaker gasket, faster plastic flow in radial and thickness directions leads to faster PT kinetics in comparison with a longer and stronger gasket. The rates of PT and plastic flows are not very sensitive to the modest change in a gasket thickness. Multiple experimental results are reproduced and interpreted. Obtained results allow one to design the desired pressure-plastic strain loading program in the experiments for searching new phases, reducing PT pressure by plastic shear, extracting kinetic properties from experiments with heterogeneous fields, and controlling homogeneity of all fields and kinetics of PTs.

  15. Containment of fluid samples in the hydrothermal diamond-anvil cell without the use of metal gaskets: performance and advantages for in situ analysis.

    PubMed

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

    2008-11-01

    Metal gaskets (Re, Ir, Inconel, or stainless steel) normally used to contain fluid samples in the hydrothermal diamond-anvil cell (HDAC) are sometimes undesirable due to possible contamination and to gasket deformation at high pressures and temperatures resulting in nonisochoric behavior. Furthermore, in x-ray spectroscopic experiments, metal gaskets may attenuate the incident x-ray beam and emitted fluorescence x-rays, and the interaction of scattered radiation with the gasket may produce fluorescence that interferes with the x-ray spectrum of the sample. New arrangements and procedures were tested for the operation of the HDAC without using the metal gaskets. Distilled, de-ionized water was loaded into the sample chamber, a laser-milled recess 300 microm in diameter and approximately 50 microm deep centered in the 1.0 mm face of the lower diamond anvil, and sealed by pressing the top diamond anvil face directly against the lower one without a metal gasket in between. A maximum sample pressure of 202 MPa at 617 degrees C was maintained for a duration of 10 min without evidence of leakage. A small change in fluid density was observed in one experiment where the sample was held at 266 MPa at 708 degrees C for 10 min. The gasketless HDAC was also employed in x-ray absorption spectroscopy experiments, where, in addition to the sample chamber in the lower diamond, two grooves were milled at a 90 degrees angle to each other around the sample chamber to minimize the attenuation of incident and fluorescent x rays. With a minimum distance between the sample chamber and the grooves of 80 microm, a pressure of 76 MPa at 500 degrees C was maintained for 2 h with no change in the original fluid density.

  16. Rhenium-catalysed dehydrogenative borylation of primary and secondary C(sp3)-H bonds adjacent to a nitrogen atom.

    PubMed

    Murai, Masahito; Omura, Tetsuya; Kuninobu, Yoichiro; Takai, Kazuhiko

    2015-03-18

    Rhenium-catalysed C(sp(3))-H bond borylation in the absence of any oxidant, hydrogen acceptor, or external ligand, with the generation of H2 as the sole byproduct is described. The transformation, which represents a rare example of rhenium-catalysed C(sp(3))-H bond functionalisation, features high atom efficiency and simple reaction conditions.

  17. Isotopic determinations of rhenium and osmium in meteorites by using fusion, distillation and ion-exchange separations

    USGS Publications Warehouse

    Morgan, J.W.; Walker, R.J.

    1989-01-01

    A stable isotope-dilution method using resonance ionization mass spectrometry is suitable for the determination of rhenium and osmium abundances and osmium isotopic composition in carbonaceous chondrites and iron meteorites. The chemical procedure involves sodium peroxide fusion, followed by distillation of osmium from sulfuric acid/hydrogen peroxide and subsequent anion-exchange separation of rhenium from the same solution. ?? 1989.

  18. Submersion criticality safety of tungsten-rhenium urania cermet fuel for space propulsion and power applications

    SciTech Connect

    A.E. Craft; R. C. O'Brien; S. D. Howe; J. C. King

    2014-07-01

    Nuclear thermal rockets are the preferred propulsion technology for a manned mission to Mars, and tungsten–uranium oxide cermet fuels could provide significant performance and cost advantages for nuclear thermal rockets. A nuclear reactor intended for use in space must remain subcritical before and during launch, and must remain subcritical in launch abort scenarios where the reactor falls back to Earth and becomes submerged in terrestrial materials (including seawater, wet sand, or dry sand). Submersion increases reflection of neutrons and also thermalizes the neutron spectrum, which typically increases the reactivity of the core. This effect is typically very significant for compact, fast-spectrum reactors. This paper provides a submersion criticality safety analysis for a representative tungsten/uranium oxide fueled reactor with a range of fuel compositions. Each submersion case considers both the rhenium content in the matrix alloy and the uranium oxide volume fraction in the cermet. The inclusion of rhenium significantly improves the submersion criticality safety of the reactor. While increased uranium oxide content increases the reactivity of the core, it does not significantly affect the submersion behavior of the reactor. There is no significant difference in submersion behavior between reactors with rhenium distributed within the cermet matrix and reactors with a rhenium clad in the coolant channels. The combination of the flooding of the coolant channels in submersion scenarios and the presence of a significant amount of spectral shift absorbers (i.e. high rhenium concentration) further decreases reactivity for short reactor cores compared to longer cores.

  19. [Influence of antitumor system rhenium-platinum on biochemical state of the liver].

    PubMed

    Ivchuk, V V; Polishko, T M; Golichenko, O A; Shtemenko, O V; Shtemenko, N I

    2011-01-01

    Influence of the antitumour rhenium-platinum system on biochemical liver characteristics in the model of tumor growth (Guerin carcinoma) was studied and possible hepatoprotective activity of rhenium cluster compounds when introducing them in different forms was shown, that was confirmed by decreasing of diagnostic enzymes activity in blood (aminotransferase--AST 6 times and ALT 5.6 times, lactatedehydrogenase 4.9 times, gamma-glutamyltranspeptidase 3.6 times) and normalization of morphological state of the liver cells. The hepatoprotective activity of the cluster rhenium compound with adamanthyl ligands was confirmed in the model of acute toxic hepatitis. Introduction of this compound led to reduction of the concentration of MDA in homogenates of liver tissue (2 times), and in blood plasma (3.8 times); to reduction of levels of diagnostic liver enzymes in blood--AST and ALT 5.8 and 5.5 times respectively in comparison with control group. Some aspects of the mechanism of hepatoprotection were discussed, that included the presence of conjugated systems around the quadrupol rhenium-rhenium bond and alkyl radicals with significant positive inductive effects.

  20. Supported Rhenium Complexes: Almost Uniform Rhenium Tricarbonyls Synthesized from CH[subscript 3]Re(CO)[subscript 5] and HY Zeolite

    SciTech Connect

    Lobo-Lapidus, Rodrigo J.; Gates, Bruce C.

    2010-12-07

    Supported rhenium complexes were prepared from CH{sub 3}Re(CO){sub 5} and dealuminated HY zeolite or NaY zeolite, each with a Si/Al atomic ratio of 30. The samples were characterized with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies. EXAFS data characterizing the sample formed by the reaction of CH{sub 3}Re(CO){sub 5} with dealuminated HY zeolite show that the rhenium complexes were bonded to the zeolite frame, incorporating, on average, three carbonyl ligands per Re atom (as shown by Re-C and multiple-scattering Re-O EXAFS contributions). The IR spectra, consistent with this result, show that the supported rhenium carbonyls were bonded near aluminum sites of the zeolite, as shown by the decrease in intensity of the IR bands characterizing the acidic silanol groups resulting from the reaction of the rhenium carbonyl with the zeolite. This supported metal complex was characterized by narrow peaks in the {nu}{sub CO} region of the IR spectrum, indicating highly uniform species. In contrast, the species formed from CH{sub 3}Re(CO){sub 5} on NaY zeolite lost fewer carbonyl ligands than those formed on HY zeolite and were significantly less uniform, as indicated by the greater breadth of the {nu}{sub CO} bands in the IR spectra. The results show the importance of zeolite H{sup +} sites for the formation of uniform supported rhenium carbonyls from CH{sub 3}Re(CO){sub 5}; the formation of such uniform complexes did not occur on the NaY zeolite.

  1. Leakage Through a Channel Formed by a Gasket, a Sealing Surface, and a Filament Trapped Between Them

    NASA Technical Reports Server (NTRS)

    Russell, John; Adams, Frederick

    1996-01-01

    Plumbing for the transport of liquid Hydrogen or liquid Oxygen at the Kennedy Space Center (KSC) is very critical. Every piece of hardware for handling such a hazardous cryogen is subject to testing prior to installation and use. Safe, realistic testing of all such hardware is prohibitively expensive, which leads, perforce, to expidients such as: (1) lead testing with non-flammable tracer fluids (e.g, liquid nitrogen) and (2) leak testing with room temperature tracer fluids (e.g. liquid helium). Such expedients undermine the realism of the tests. If however, one could apply rational fluid dynamics methods to derive a general analytical expression with which one could relate the throughput of gaseous Helium through a given leak channel to the throughput of liquid Hydrogen through the same channel, then one could recover much of the information that one would otherwise forfeit through these expedients. These facts lead to the following questions: (1) What would be an example of a generic flaw in a gasket?; and (2) How can one calculate the flow of fluid in it? The report addresses these questions. It considers a particular leak geometry, namely one formed by a gasket, a sealing surface, and a filament trapped between them (so that the cross section of the leak channel is a flat bottomed curvilinear triangle, two sides of which are circular arcs and which has cusps on all three corners).

  2. The rhenium tris(dithiolene) electron transfer series: calibrating covalency.

    PubMed

    Sproules, Stephen; Weyhermüller, Thomas; Goddard, Richard; Wieghardt, Karl

    2011-12-19

    Four members of the rhenium tris(dithiolene) electron transfer series have been prepared, [Re(S(2)C(2)R(2))(3)](z) {R = Ph, z = 1+ (1), 0 (2), 1- (3); R = CN, z = 2- (4)}, with the anions in 3 and 4 structurally characterized. The intraligand C-S and C-C bond lengths for 3 vs 2 are indicative of ligand reduction concomitant with an overall distorted trigonal prismatic geometry (Θ = 26.3° cf. 3.8° in 2). The distorted octahedral ReS(6) polyhedron in 4 (Θ = 38.3°) indicates reduction of the metal to a Re(IV) d(3) central ion. This series has been probed by sulfur K-edge X-ray absorption spectroscopy (XAS), and the electronic structures are unambiguously defined as follows: [Re(V)(L(3)(4-))](1+) (S = 0) for the monocation in 1; [Re(V)(L(3)(5-•))](0) (S = (1)/(2)) for neutral 2; [Re(V)(L(3)(6-))](1-) (S = 0) for the monoanion in 3; and [Re(IV)(L(3)(6-))](2-) (S = (1)/(2)) for the dianion in 4. The sulfur 3p character in the frontier orbitals-the covalency-is estimated by two different approaches. Method A utilizes the radial dipole integral (I(s)) derived from the S 1s → 4p transition, whereas method B, involves time-dependent density functional theoretical (TD-DFT) calculation of the pre-edge transitions and calibrated to the intensity in [Re(pdt)(3)] (pdt(2-) = 1,2-diphenyl-1,2-dithiolate). The two estimates are contrasted for the rhenium series and extended to the [V(pdt)(3)](0/1-), and [Mo(mdt)(3)](0/1-/2-) (mdt(2-) = 1,2-dimethyl-1,2-dithiolate) series, ultimately providing a refined description of the contested electronic structure of neutral molybdenum (and tungsten) tris(dithiolenes) compounds. © 2011 American Chemical Society

  3. Ductility and impact resistance of P/M molybdenum-rhenium alloys

    SciTech Connect

    Leichtfried, Gerhard; Schneibel, Joachim H; Heilmaier, M.

    2006-01-01

    Mo-Re alloys containing between 5 and 47.5 wt pct Re were fabricated from Mo and Mo-Re powders by sintering and hot radial forging. The mechanical properties of as-forged, stress-relieved, and recrystallized specimens were examined. Up to a concentration of 41 wt pct Re, the Charpy ductile-to-brittle transition temperature decreased monotonically with increasing rhenium concentration. Consistent with this, bend angles for fracture at T = -100 C increased monotonically with increasing rhenium concentration. Between 10 and 41 wt pct rhenium, the room-temperature tensile ductility of recrystallized Mo-Re remained nearly constant with values on the order of 35 to 45 pct. This result differs from the low ductility values observed previously by Lundberg (1997) for compositions on either side of Mo-13 wt pct Re.

  4. Structure and Phase Composition of Ni-Al-Cr Alloy Alloyed by Rhenium and Lanthanum

    NASA Astrophysics Data System (ADS)

    Nikonenko, E. L.; Popova, N. A.; Dement, T. V.; Koneva, N. A.

    2017-06-01

    The paper presents the transmission and the scanning electron microscope investigations of the phase composition and fine structure of Ni-Al-Cr-based alloy alloyed by rhenium and lanthanum. The alloy is prepared by the directional crystallization technique and then subjected to 1150°C annealing during 1 hour. It is shown that γ- and γ'-phases are major and have a face-centered cubic crystal system. Solid solutions of γ- and γ'-phase have a disordered and an ordered atom arrangement, respectively. The latter has L12 superstructure. It is found that rhenium and lanthanum alloying leads to the structural modification of γ'-phase quasi-cuboids. Not dissolving in major phases, rhenium and lanthanum are phase-formation elements and form σ-phase. The phase composition and morphology of these phases are studied and described.

  5. Thermodynamic stability and unusual strength of ultra-incompressible rhenium nitrides

    SciTech Connect

    Zhang, R. F.; Lin, Zhijun; Mao, Ho-kwang; Zhao, Yusheng

    2011-02-11

    We report on a comprehensive study of thermodynamic and mechanical properties as well as a bond-deformation mechanism on ultra-incompressible Re{sub 2} N and Re{sub 3} N. The introduction of nitrogen into the rhenium lattice leads to thermodynamic instability in Re{sub 2} N at ambient conditions and enhanced incompressibility and strength for both rhenium nitrides. Rhenium nitrides, however, show substantially lower ideal shear strength than hard ReB{sub 2} and superhard c -BN, suggesting that they cannot be intrinsically superhard. An intriguing soft “ionic bond mediated plastic deformation” mechanism is revealed to underline the physical origin of their unusual mechanical strength. These results suggest a need to reformulate the design concept of intrinsically superhard transition-metal nitrides, borides, and carbides.

  6. Highly Selective Deoxydehydration of Tartaric Acid over Supported and Unsupported Rhenium Catalysts with Modified Acidities.

    PubMed

    Li, Xiukai; Zhang, Yugen

    2016-10-06

    The deoxydehydration (DODH) of sugar acids to industrially important carboxylic acids is a very attractive topic. Oxorhenium complexes are the most-often employed DODH catalysts. Because of the acidity of the rhenium catalysts, the DODH products of sugar acids were usually in the form of mixture of free carboxylic acids and esters. Herein, we demonstrate strategies for the selective DODH of sugar acids to free carboxylic acids by tuning the Lewis acidity or the Brønsted acidity of the rhenium-based catalysts. Starting from tartaric acid, up to 97 % yield of free maleic acid was achieved. Based on our strategies, functional polymer immobilized heterogeneous rhenium catalysts were also developed for the selective DODH conversion of sugar acids. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Thermocouples of tantalum and rhenium alloys for more stable vacuum-high temperature performance

    NASA Technical Reports Server (NTRS)

    Morris, J. F. (Inventor)

    1977-01-01

    Thermocouples of the present invention provide stability and performance reliability in systems involving high temperatures and vacuums by employing a bimetallic thermocouple sensor wherein each metal of the sensor is selected from a group of metals comprising tantalum and rhenium and alloys containing only those two metals. The tantalum, rhenium thermocouple sensor alloys provide bare metal thermocouple sensors having advantageous vapor pressure compatibilities and performance characteristics. The compatibility and physical characteristics of the thermocouple sensor alloys of the present invention result in improved emf, temperature properties and thermocouple hot junction performance. The thermocouples formed of the tantalum, rhenium alloys exhibit reliability and performance stability in systems involving high temperatures and vacuums and are adaptable to space propulsion and power systems and nuclear environments.

  8. Methods for the separation of rhenium, osmium and molybdenum applicable to isotope geochemistry

    USGS Publications Warehouse

    Morgan, J.W.; Golightly, D.W.; Dorrzapf, A.F.

    1991-01-01

    Effective methods are described for the chemical separation of rhenium, osmium and molybdenum. The methods are based on distillation and anion-exchange chromatography, and have been the basis for rhenium-osmium isotope studies of ore deposits and meteorites. Successful anion-exchange separation of osmium requires both recognition and careful control of the osmium species in solution; thus, distillation of osmium tetroxide from a mixture of sulfuric acid and hydrogen peroxide is preferred to anion-exchange. Distribution coefficients measured for perrhenate in sulfuric acid media are sufficiently high (Kd > 500) for rhenium to be directly loaded onto an ion-exchange column from a distillation residue and subsequently eluted with nitric acid. Polymerization of molybdenum species during elution is prevented by use of a solution that is 1M in hydrochloric acid and 1M in sodium chloride. ?? 1991.

  9. Thiophene hydrodesulfurization over transition metal surfaces: structure insensitive over molybdenum and structure sensitive over rhenium

    SciTech Connect

    Bussell, M.E.; Gellman, A.J.; Somorjai, G.A.

    1988-04-01

    In this note the authors present results of thiophene hydrodesulfurization (HDS) experiments over molybdenum and rhenium single crystals. Previous work in their laboratory showed that a Mo(100) single crystal catalyzes thiophene HDS and that the product distribution is similar to the distribution obtained over an unsupported molybdenum disulfide (MoS/sub 2/) catalyst. The similarity of these results suggests that by determining the effects of surface structure and adsorbate overlayers (C, S) on thiophene HDS over molybdenum single crystals, one can gain insight about the nature of the active sites on MoS/sub 2/-based catalysts. This led the authors to expand studies to molybdenum single crystals of different surface orientations. They have also begun to investigate thiophene HDS over rhenium single crystals; rhenium disulfide (ReS/sub 2/) has been shown to be a more active HDS catalyst than MoS/sub 2/.

  10. Rhenium uptake and distribution in phaeophyceae macroalgae, Fucus vesiculosus.

    PubMed

    Racionero-Gómez, B; Sproson, A D; Selby, D; Gröcke, D R; Redden, H; Greenwell, H C

    2016-05-01

    Owing to Rhenium (Re) having no known biological role, it is not fully understood how Re is concentrated in oil kerogens. A commonly held assumption is that Re is incorporated into decomposing biomass under reducing conditions. However, living macroalgae also concentrate Re to several orders of magnitude greater than that of seawater. This study uses Fucus vesiculosus to assess Re uptake and its subsequent localization in the biomass. It is demonstrated that the Re abundance varies within the macroalgae and that Re is not located in one specific structure. In F. vesiculosus, the uptake and tolerance of Re was evaluated via tip cultures grown in seawater of different Re(VII) compound concentrations (0-7450 ng g(-1)). A positive correlation is shown between the concentration of Re-doped seawater and the abundance of Re accumulated in the tips. However, significant differences between Re(VII) compounds are observed. Although the specific cell structures where the Re is localized is not known, our findings suggest that Re is not held within chloroplasts or cytoplasmic proteins. In addition, metabolically inactivated F. vesiculosus does not accumulate Re, which indicates that Re uptake is via syn-life bioadsorption/bioaccumulation and that macroalgae may provide a source for Re phytomining and/or bioremediation.

  11. Rhenium uptake and distribution in phaeophyceae macroalgae, Fucus vesiculosus

    PubMed Central

    Racionero-Gómez, B.; Sproson, A. D.; Selby, D.; Gröcke, D. R.; Redden, H.; Greenwell, H. C.

    2016-01-01

    Owing to Rhenium (Re) having no known biological role, it is not fully understood how Re is concentrated in oil kerogens. A commonly held assumption is that Re is incorporated into decomposing biomass under reducing conditions. However, living macroalgae also concentrate Re to several orders of magnitude greater than that of seawater. This study uses Fucus vesiculosus to assess Re uptake and its subsequent localization in the biomass. It is demonstrated that the Re abundance varies within the macroalgae and that Re is not located in one specific structure. In F. vesiculosus, the uptake and tolerance of Re was evaluated via tip cultures grown in seawater of different Re(VII) compound concentrations (0–7450 ng g−1). A positive correlation is shown between the concentration of Re-doped seawater and the abundance of Re accumulated in the tips. However, significant differences between Re(VII) compounds are observed. Although the specific cell structures where the Re is localized is not known, our findings suggest that Re is not held within chloroplasts or cytoplasmic proteins. In addition, metabolically inactivated F. vesiculosus does not accumulate Re, which indicates that Re uptake is via syn-life bioadsorption/bioaccumulation and that macroalgae may provide a source for Re phytomining and/or bioremediation. PMID:27293798

  12. Rhenium-osmium isotope systematics of carbonaceous chondrites.

    PubMed

    Walker, R J; Morgan, J W

    1989-01-27

    Rhenium and osmium concentrations and Os isotopic compositions of eight carbonaceous chondrites, one LL3 ordinary chondrite, and two iron meteorites were determined by resonance ionization mass spectrometry. Iron meteorite (187)Re/(186)Os and (l87)Os/(l86)Os ratios plot on the previously determined iron meteorite isochron, but most chondrite data plot 1 to 2 percent above this meteorite isochron. This suggests either that irons have significantly younger Re-Os closure ages than chondrites or that chondrites were formed from precursor materials with different chemical histories from the precursors of irons. Some samples of Semarkona (LL3) and Murray (C2M) meteorites plot 4 to 6 percent above the iron meteorite isochron, well above the field delineated by other chondrites. Murray may have lost Re by aqueous leaching during its preterrestrial history. Semarkona could have experienced a similar loss of Re, but only slight aqueous alteration is evident in the meteorite. Therefore, the isotopic composition of Semarkona could reflect assembly of isotopically heterogeneous components subsequent to 4.55 billion years ago or Os isotopic heterogeneities in the primordial solar nebula.

  13. Polymer Photovoltaic Cells with Rhenium Oxide as Anode Interlayer

    PubMed Central

    Wei, Jinyu; Bai, Dongdong; Yang, Liying

    2015-01-01

    The effect of a new transition metal oxide, rhenium oxide (ReO3), on the performance of polymer solar cells based on regioregular poly(3-hexylthiophene) (P3HT) and methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) blend as buffer layer was investigated. The effect of the thickness of ReO3 layer on electrical characteristics of the polymer solar cells was studied. It is found that insertion of ReO3 interfacial layer results in the decreased performance for P3HT: PCBM based solar cells. In order to further explore the mechanism of the decreasing of the open-circuit voltage (Voc), the X-ray photoelectron spectroscopy (XPS) is used to investigate the ReO3 oxidation states. Kelvin Probe method showed that the work function of the ReO3 is estimated to be 5.13eV after thermal evaporation. The results indicated the fact that a portion of ReO3 decomposed during thermal evaporation process, resulting in the formation of a buffer layer with a lower work function. As a consequence, a higher energy barrier was generated between the ITO and the active layer. PMID:26226439

  14. Rhenium Dichalcogenides: Layered Semiconductors with Two Vertical Orientations.

    PubMed

    Hart, Lewis; Dale, Sara; Hoye, Sarah; Webb, James L; Wolverson, Daniel

    2016-02-10

    The rhenium and technetium diselenides and disulfides are van der Waals layered semiconductors in some respects similar to more well-known transition metal dichalcogenides (TMD) such as molybdenum sulfide. However, their symmetry is lower, consisting only of an inversion center, so that turning a layer upside-down (that is, applying a C2 rotation about an in-plane axis) is not a symmetry operation, but reverses the sign of the angle between the two nonequivalent in-plane crystallographic axes. A given layer thus can be placed on a substrate in two symmetrically nonequivalent (but energetically similar) ways. This has consequences for the exploitation of the anisotropic properties of these materials in TMD heterostructures and is expected to lead to a new source of domain structure in large-area layer growth. We produced few-layer ReS2 and ReSe2 samples with controlled "up" or "down" orientations by micromechanical cleavage and we show how polarized Raman microscopy can be used to distinguish these two orientations, thus establishing Raman as an essential tool for the characterization of large-area layers.

  15. Polymer Photovoltaic Cells with Rhenium Oxide as Anode Interlayer.

    PubMed

    Wei, Jinyu; Bai, Dongdong; Yang, Liying

    2015-01-01

    The effect of a new transition metal oxide, rhenium oxide (ReO3), on the performance of polymer solar cells based on regioregular poly(3-hexylthiophene) (P3HT) and methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) blend as buffer layer was investigated. The effect of the thickness of ReO3 layer on electrical characteristics of the polymer solar cells was studied. It is found that insertion of ReO3 interfacial layer results in the decreased performance for P3HT: PCBM based solar cells. In order to further explore the mechanism of the decreasing of the open-circuit voltage (Voc), the X-ray photoelectron spectroscopy (XPS) is used to investigate the ReO3 oxidation states. Kelvin Probe method showed that the work function of the ReO3 is estimated to be 5.13eV after thermal evaporation. The results indicated the fact that a portion of ReO3 decomposed during thermal evaporation process, resulting in the formation of a buffer layer with a lower work function. As a consequence, a higher energy barrier was generated between the ITO and the active layer.

  16. Graphite-Conjugated Rhenium Catalysts for Carbon Dioxide Reduction

    SciTech Connect

    Oh, Seokjoon; Gallagher, James R.; Miller, Jeffrey T.; Surendranath, Yogesh

    2016-02-17

    Condensation of fac-Re(5,6-diamino-1,10-phenanthroline)(CO)(3)Cl to o-quinone edge defects on graphitic carbon surfaces generates graphite-conjugated rhenium (GCC-Re) catalysts that are highly active for CO2 reduction to CO in acetonitrile electrolyte. X-ray photo-electron and X-ray absorption spectroscopies establish the formation of surface-bound Re centers with well-defined coordination environments. GCC-Re species on glassy carbon surfaces display catalytic currents greater than 50 mA cm(-2) with 96 +/- 3% Faradaic efficiency for CO production. Normalized for the number of Re active sites, GCC-Re catalysts exhibit higher turnover frequencies than that of a soluble molecular analogue, fac-Re(1,10-phenanthroline)(CO)(3)Cl, and turnover numbers greater than 12,000. In contrast to the molecular analogue, GCC-Re surfaces display a Tafel slope of 150 mV/decade, indicative of a catalytic mechanism involving rate-limiting one-electron transfer. This work establishes graphite conjugation as a powerful strategy for generating well-defined, tunable, heterogeneous electrocatalysts on ubiquitous graphitic carbon surfaces.

  17. Rhenium-osmium isotope systematics of carbonaceous chondrites

    USGS Publications Warehouse

    Walker, R.J.; Morgan, J.W.

    1989-01-01

    Rhenium and osmium concentrations and Os isotopic compositions of eight carbonaceous chondrites, one LL3 ordinary chondrite, and two iron meteorites were determined by resonance ionization mass spectrometry. Iron meteorite 187Re/186Os and 187OS/186Os ratios plot on the previously determined iron meteorite isochron, but most chondrite data plot 1 to 2 percent above this meteorite isochron. This suggests either that irons have significantly younger Re-Os closure ages than chondrites or that chondrites were formed from precursor materials with different chemical histories from the precursors of irons. Some samples of Semarkona (LL3) and Murray (C2M) meteorites plot 4 to 6 percent above the iron meteorite isochron, well above the field delineated by other chondrites. Murray may have lost Re by aqueous leaching during its preterrestrial history. Semarkona could have experienced a similar loss of Re, but only slight aqueous alteration is evident in the meteorite. Therefore, the isotopic composition of Semarkona could reflect assembly of isotopically heterogeneous components subsequent to 4.55 billion years ago or Os isotopic heterogeneities in the primordial solar nebula.

  18. Nonlinear Saturable and Polarization-induced Absorption of Rhenium Disulfide

    PubMed Central

    Cui, Yudong; Lu, Feifei; Liu, Xueming

    2017-01-01

    Monolayer of transition metal dichalcogenides (TMDs), with lamellar structure as that of graphene, has attracted significant attentions in optoelectronics and photonics. Here, we focus on the optical absorption response of a new member TMDs, rhenium disulphide (ReS2) whose monolayer and bulk forms have the nearly identical band structures. The nonlinear saturable and polarization-induced absorption of ReS2 are investigated at near-infrared communication band beyond its bandgap. It is found that the ReS2-covered D-shaped fiber (RDF) displays the remarkable polarization-induced absorption, which indicates the different responses for transverse electric (TE) and transverse magnetic (TM) polarizations relative to ReS2 plane. Nonlinear saturable absorption of RDF exhibits the similar saturable fluence of several tens of μJ/cm2 and modulation depth of about 1% for ultrafast pulses with two orthogonal polarizations. RDF is utilized as a saturable absorber to achieve self-started mode-locking operation in an Er-doped fiber laser. The results broaden the operation wavelength of ReS2 from visible light to around 1550 nm, and numerous applications may benefit from the anisotropic and nonlinear absorption characteristics of ReS2, such as in-line optical polarizers, high-power pulsed lasers, and optical communication system. PMID:28053313

  19. Nonlinear Saturable and Polarization-induced Absorption of Rhenium Disulfide.

    PubMed

    Cui, Yudong; Lu, Feifei; Liu, Xueming

    2017-01-05

    Monolayer of transition metal dichalcogenides (TMDs), with lamellar structure as that of graphene, has attracted significant attentions in optoelectronics and photonics. Here, we focus on the optical absorption response of a new member TMDs, rhenium disulphide (ReS2) whose monolayer and bulk forms have the nearly identical band structures. The nonlinear saturable and polarization-induced absorption of ReS2 are investigated at near-infrared communication band beyond its bandgap. It is found that the ReS2-covered D-shaped fiber (RDF) displays the remarkable polarization-induced absorption, which indicates the different responses for transverse electric (TE) and transverse magnetic (TM) polarizations relative to ReS2 plane. Nonlinear saturable absorption of RDF exhibits the similar saturable fluence of several tens of μJ/cm(2) and modulation depth of about 1% for ultrafast pulses with two orthogonal polarizations. RDF is utilized as a saturable absorber to achieve self-started mode-locking operation in an Er-doped fiber laser. The results broaden the operation wavelength of ReS2 from visible light to around 1550 nm, and numerous applications may benefit from the anisotropic and nonlinear absorption characteristics of ReS2, such as in-line optical polarizers, high-power pulsed lasers, and optical communication system.

  20. Nonlinear Saturable and Polarization-induced Absorption of Rhenium Disulfide

    NASA Astrophysics Data System (ADS)

    Cui, Yudong; Lu, Feifei; Liu, Xueming

    2017-01-01

    Monolayer of transition metal dichalcogenides (TMDs), with lamellar structure as that of graphene, has attracted significant attentions in optoelectronics and photonics. Here, we focus on the optical absorption response of a new member TMDs, rhenium disulphide (ReS2) whose monolayer and bulk forms have the nearly identical band structures. The nonlinear saturable and polarization-induced absorption of ReS2 are investigated at near-infrared communication band beyond its bandgap. It is found that the ReS2-covered D-shaped fiber (RDF) displays the remarkable polarization-induced absorption, which indicates the different responses for transverse electric (TE) and transverse magnetic (TM) polarizations relative to ReS2 plane. Nonlinear saturable absorption of RDF exhibits the similar saturable fluence of several tens of μJ/cm2 and modulation depth of about 1% for ultrafast pulses with two orthogonal polarizations. RDF is utilized as a saturable absorber to achieve self-started mode-locking operation in an Er-doped fiber laser. The results broaden the operation wavelength of ReS2 from visible light to around 1550 nm, and numerous applications may benefit from the anisotropic and nonlinear absorption characteristics of ReS2, such as in-line optical polarizers, high-power pulsed lasers, and optical communication system.

  1. Formation and stability of point defects in monolayer rhenium disulfide

    NASA Astrophysics Data System (ADS)

    Horzum, S.; ćakır, D.; Suh, J.; Tongay, S.; Huang, Y.-S.; Ho, C.-H.; Wu, J.; Sahin, H.; Peeters, F. M.

    2014-04-01

    Recently, rhenium disulfide (ReS2) monolayers were experimentally extracted by conventional mechanical exfoliation technique from as-grown ReS2 crystals. Unlike the well-known members of transition metal dichalcogenides (TMDs), ReS2 crystallizes in a stable distorted-1T structure and lacks an indirect to direct gap crossover. Here we present an experimental and theoretical study of the formation, energetics, and stability of the most prominent lattice defects in monolayer ReS2. Experimentally, irradiation with 3-MeV He+2 ions was used to break the strong covalent bonds in ReS2 flakes. Photoluminescence measurements showed that the luminescence from monolayers is mostly unchanged after highly energetic α particle irradiation. In order to understand the energetics of possible vacancies in ReS2 we performed systematic first-principles calculations. Our calculations revealed that the formation of a single sulfur vacancy has the lowest formation energy in both Re and S rich conditions and a random distribution of such defects are energetically more preferable. Sulfur point defects do not result in any spin polarization whereas the creation of Re-containing point defects induce magnetization with a net magnetic moment of 1-3μB. Experimentally observed easy formation of sulfur vacancies is in good agreement with first-principles calculations.

  2. Synthesis, crystal structure and magnetic properties of a novel heterobimetallic rhenium(IV)-dysprosium(III) chain.

    PubMed

    Pejo, Carolina; Guedes, Guilherme P; Novak, Miguel A; Speziali, Nivaldo L; Chiozzone, Raúl; Julve, Miguel; Lloret, Francesc; Vaz, Maria G F; González, Ricardo

    2015-06-08

    The use of the mononuclear rhenium(IV) precursor [ReBr5 (H2 pydc)](-) (H2 pydc=3,5-pyridinedicarboxylic acid) as a metalloligand towards dysprosium(III) afforded the first heterobimetallic Re(IV) -Dy(III) complex. Crystal structures and static and dynamic magnetic properties of both rhenium-containing species are reported herein. The 5d-4f compound shows an extended 1D structure and the AC magnetic measurements reveal frequency dependence at low temperature suggesting slow relaxation of the magnetization.

  3. Photo field-emission spectroscopy of optical transitions in the band structure of rhenium

    NASA Astrophysics Data System (ADS)

    Radoń, T.; Kleint, Ch.

    1984-09-01

    Photo field-emission (PFE) current-voltage curves of clean and barium covered rhenium have been determined with an argon ion laser and phase sensitive detection. Field strength and work function were obtained from Fowler-Nordheim plots of the field emission currents. According to a two-step PFE model the knees of the PFE characteristics are ascribed to optical transitions in the Brillouin zone near the Fermi level. Most of the observed excitations could be correlated to direct transitions in the rhenium band structure as calculated by Mattheiss including spin-orbit coupling.

  4. Effect of preliminary plastic deformation on the anodic behavior of molybdenum-rhenium alloys

    SciTech Connect

    Amirkhanova, N.A.; Tatarinova, O.M.

    1988-07-01

    Two molybdenum-rhenium alloys obtained by the method of vacuum melting and containing 20% and 40% rhenium were investigated for their anodic behavior following heating and bulk forging to develop different degrees of deformation. Their stationary potentials were determined in solutions of a number of sodium salts and polarization measurements were made using a rotating disk electrode. The rate of removal for different working-stress values was determined on an apparatus simulating the electrochemical sizing process. Surface microstructure was observed by metallographic microscopy. The increase in the rate of anodic dissolution of the alloys was determined to be correct for degrees of deformation to 10%.

  5. Tungsten-rhenium thin film thermocouples for SiC-based ceramic matrix composites.

    PubMed

    Tian, Bian; Zhang, Zhongkai; Shi, Peng; Zheng, Chen; Yu, Qiuyue; Jing, Weixuan; Jiang, Zhuangde

    2017-01-01

    A tungsten-rhenium thin film thermocouple is designed and fabricated, depending on the principle of thermal-electric effect caused by the high temperature. The characteristics of thin film thermocouples in different temperatures are investigated via numerical analysis and analog simulation. The working mechanism and thermo-electric features of the thermocouples are analyzed depending on the simulation results. Then the thin film thermocouples are fabricated and calibrated. The calibration results show that the thin film thermocouples based on the tungsten-rhenium material achieve ideal static characteristics and work well in the practical applications.

  6. Mechanistic insights into the rhenium-catalyzed alcohol-to-olefin dehydration reaction.

    PubMed

    Korstanje, Ties J; Jastrzebski, Johann T B H; Klein Gebbink, Robertus J M

    2013-09-23

    Rhenium-based complexes are powerful catalysts for the dehydration of various alcohols to the corresponding olefins. Here, we report on both experimental and theoretical (DFT) studies into the mechanism of the rhenium-catalyzed dehydration of alcohols to olefins in general, and the methyltrioxorhenium-catalyzed dehydration of 1-phenylethanol to styrene in particular. The experimental and theoretical studies are in good agreement, both showing the involvement of several proton transfers, and of a carbenium ion intermediate in the catalytic cycle. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Tungsten-rhenium thin film thermocouples for SiC-based ceramic matrix composites

    NASA Astrophysics Data System (ADS)

    Tian, Bian; Zhang, Zhongkai; Shi, Peng; Zheng, Chen; Yu, Qiuyue; Jing, Weixuan; Jiang, Zhuangde

    2017-01-01

    A tungsten-rhenium thin film thermocouple is designed and fabricated, depending on the principle of thermal-electric effect caused by the high temperature. The characteristics of thin film thermocouples in different temperatures are investigated via numerical analysis and analog simulation. The working mechanism and thermo-electric features of the thermocouples are analyzed depending on the simulation results. Then the thin film thermocouples are fabricated and calibrated. The calibration results show that the thin film thermocouples based on the tungsten-rhenium material achieve ideal static characteristics and work well in the practical applications.

  8. Synthesis and spectroscopic characterization of super-stable rhenium(V)porphyrins

    NASA Astrophysics Data System (ADS)

    Bichan, N. G.; Tyulyaeva, E. Yu.; Khodov, I. A.; Lomova, T. N.

    2014-03-01

    The preparation of rhenium(V) porphyrin complexes {μ-oxo-bis[(oxo)(5,10,15,20-tetraphenyl-21H,23H-porphinato)rhenium(V)] [OReTPP]2O (1), (oxo)(phenoxo)(2,3,7,8,12,13,17,18-octaethyl-5-monophenyl-21H,23H-porphinato)rhenium(V) ORe(PhO)MPOEP (2), (cloro)(oxo)(2,3,7,8,12,13,17,18-octaethyl-5,15-diphenyl-21H,23H-porphinato)rhenium(V) ORe(Cl)5,15DPOEP (4), and (oxo)(phenoxo)(2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphinato)rhenium(V) ORe(PhO)OEP (5)} by the interaction of H2ReCl6 with corresponding porphyrin in boiling phenol is described. (Cloro)(oxo)(2,3,7,8,12,13,17,18-octaethyl-5-monophenyl-21H,23H-porphinato)rhenium(V) ORe(Cl)MPOEP (3) and (oxo)(chloro)(2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphinato)rhenium(V) ORe(Cl)OEP (6) have been prepared by the reaction of axial-ligand substitution from (2) and (5), respectively. Compounds (2-4) were newly synthesized. Characterization of the compounds (1-6) reported herein was made mainly by UV-Visible, IR, 1Н NMR, 1H1H 2D COSY, 1H1H 2D DOSY, 1H1H 2D ROESY, 1H1H 2D TOCSY spectroscopic techniques and elemental analysis. The stability of the complexes in solutions when exposed to strong acids at the presence of atmospheric oxygen has been estimated. Compounds (2-4) and (6) show them super-stable since they do not undergo dissociation along MN bonds in concentrated H2SO4 under heating up to 363 K. Compounds (3) and (4) undergo one-electron oxidation to form stable π-cation radicals ORe(HSO)P under these conditions. The products of the reaction between all studied porphyrins and concentrated H2SO4 were isolated in CHCl3 by reprecipitation onto ice and proved to be rhenium(V) complexes ORe(HSO4)P.

  9. A rubber transfer gasket to improve the throughput of liquid-liquid extraction in 96-well plates: application to vitamin D testing.

    PubMed

    Hoofnagle, Andrew N; Laha, Thomas J; Donaldson, Thomas F

    2010-06-01

    The unmitigated rise in demand for the assessment of vitamin D status has taxed the ability of clinical mass spectrometry laboratories to preserve turn-around times. We aimed to improve the throughput of liquid-liquid extraction of plasma/serum for the assay of 25-hydroxy vitamin D. We designed and fabricated a flexible rubber gasket that seals two 96-well plates together to quantitatively transfer the contents of one plate to another. Using the transfer gasket and a dry-ice acetone bath to freeze the aqueous infranatant, we developed a novel liquid-liquid extraction workflow in a 96-well plate format. We applied the technology to the mass spectrometric quantification of 25-hydroxy vitamin D. Cross-contamination between wells was < or = 0.13%. The interassay imprecision over 132 days of clinical implementation was less than 10%. The method compared favorably to a standard liquid-liquid extraction in glass tubes (Deming slope=1.018, S(x|y)=0.022). The accuracy of the assay was 102-105% as assessed with the recently released control materials from NIST. The development of a plate-sealing gasket permits the liquid-liquid extraction of clinical specimens in a moderate-throughput workflow and the reliable assay of vitamin D status. In the future, the gasket may also prove useful in other sample preparation techniques for HPLC or mass spectrometry. Copyright 2010 Elsevier B.V. All rights reserved.

  10. Ceramic Coating Method

    DTIC Science & Technology

    2002-07-02

    platinum, protactinium , rhenium, chemically stable in oxygen or other oxidizing atmospheres. rhodium; ruthenium, samarium, scandium, silicon, tantalum; 20...high "mismatch" platinum, protactinium , rhenium, and tantalum braze layer, 30 between ceramic (e.g., A12O3 or ZrO2 ) and carbon steel, the lower-melting

  11. The Effects of Cylinder Head Gasket Opening on Engine Temperature Distribution for a Water-Cooled Engine

    NASA Astrophysics Data System (ADS)

    Jang, J. Y.; Chi, G. X.

    2017-02-01

    In a liquid-cooled engine, coolant is pumped throughout the water jacket of the engine, drawing heat from the cylinder head, pistons, combustion chambers, cylinder walls, and valves, etc. If the engine temperature is too high or too low, various problems will occur. These include overheating of the lubricating oil and engine parts, excessive stresses between engine parts, loss of power, incomplete burning of fuel, etc. Thus, the engine should be maintained at the proper operating temperature. This study investigated the effects of different cylinder head gasket opening on the engine temperature distributions in a water-cooled motorcycle engine. The numerical predictions for the temperature distribution are in good agreement with the experimental data within 20%.

  12. Natural variations in the rhenium isotopic composition of meteorites

    NASA Astrophysics Data System (ADS)

    Liu, R.; Hu, L.; Humayun, M.

    2017-03-01

    Rhenium is an important element with which to test hypotheses of isotope variation. Historically, it has been difficult to precisely correct the instrumental mass bias in thermal ionization mass spectrometry. We used W as an internal standard to correct mass bias on the MC-ICP-MS, and obtained the first precise δ187Re values ( ±0.02‰, 2SE) for iron meteorites and chondritic metal. Relative to metal from H chondrites, IVB irons are systematically higher in δ187Re by 0.14 ‰. δ187Re for other irons are similar to H chondritic metal, although some individual samples show significant isotope fractionation. Since 185Re has a high neutron capture cross section, the effect of galactic cosmic-ray (GCR) irradiation on δ187Re was examined using correlations with Pt isotopes. The pre-GCR irradiation δ187Re for IVB irons is lower, but the difference in δ187Re between IVB irons and other meteoritic metal remains. Nuclear volume-dependent fractionation for Re is about the right magnitude near the melting point of iron, but because of the refractory and compatible character of Re, a compelling explanation in terms of mass-dependent fractionation is elusive. The magnitude of a nucleosynthetic s-process deficit for Re estimated from Mo and Ru isotopes is essentially unresolvable. Since thermal processing reduced nucleosynthetic effects in Pd, it is conceivable that Re isotopic variations larger than those in Mo and Ru may be present in IVBs since Re is more refractory than Mo and Ru. Thus, the Re isotopic difference between IVBs and other irons or chondritic metal remains unexplained.

  13. Luminescence modulations of rhenium tricarbonyl complexes induced by structural variations.

    PubMed

    Bertrand, Hélène C; Clède, Sylvain; Guillot, Régis; Lambert, François; Policar, Clotilde

    2014-06-16

    Octahedral d(6) low-spin Re(I) tricarbonyl complexes are of considerable interest as noninvasive imaging probes and have been deeply studied owing to their biological stability, low toxicity, large Stokes shifts, and long luminescence lifetimes. We reported recently the bimodal IR and luminescence imaging of a Re(I) tricarbonyl complex with a Pyta ligand (4-(2-pyridyl)-1,2,3-triazole) in cells and labeled such metal-carbonyl complexes SCoMPIs for single-core multimodal probes for imaging. Re(I) tricarbonyl complexes have unique photophysical properties allowing for their unequivocal detection in cells but also present some weaknesses such as a very low luminescence quantum yield in aqueous medium. Further optimizations would thus be desirable. We therefore developed new Re(I) tricarbonyl complexes prepared from different ancillary ligands. Complexes with benzothiadiazole-triazole ligands show interesting luminescent quantum yields in acetonitrile and may constitute valuable luminescent metal complexes in organic media. A series of complexes with bidentate 1-(2-quinolinyl)-1,2,3-triazole (Taquin) and 1-(2-pyridyl)-1,2,3-triazole (Tapy) ligands bearing various 4-substituted alkyl side chains has been designed and synthesized with efficient procedures. Their photophysical properties have been characterized in acetonitrile and in a H2O/DMSO (98/2) mixture and compared with those of the parent Quinta- and Pyta-based complexes. Tapy complexes bearing long alkyl chains show impressive enhancement of their luminescent properties relative to the parent Pyta complex. Theoretical calculations have been performed to further characterize this new class of rhenium tricarbonyl complexes. Preliminary cellular imaging studies in MDA-MB231 breast cancer cells reveal a strong increase in the luminescence signal in cells incubated with the Tapy complex substituted with a C12 alkyl chain. This study points out the interesting potential of the Tapy ligand in coordination chemistry

  14. Rhenium-186-labeled monoclonal antibodies for radioimmunotherapy: preparation and evaluation.

    PubMed

    John, E; Thakur, M L; DeFulvio, J; McDevitt, M R; Damjanov, I

    1993-02-01

    Rhenium-186 has been determined to be a leading radionuclide for radioimmunotherapy. However, the use of 186Re has been limited due to the lack of a convenient and efficient method by which the radionuclide can be bound to monoclonal antibodies. We have developed a simple technique to label IgM, IgG, fragmented antibodies and tumor necrosis factor-alpha with 186Re. This technique uses ascorbic acid (AA) for controlled reduction of antibody disulfide groups to sulfhydryls and SnCl2 in citric acid for the reduction of 186ReO4-. The labeling yields as determined by instant thin-layer chromatography, molecular filtration and gel filtration were greater than 95% and the colloid formation was less than 5%. The labeled antibodies were stable when challenged with 100 and 250 molar excess of DTPA and HSA for 24 hr at 37 degrees C. SDS-PAGE analysis and autoradiography of labeled IgM, IgG and F(ab')2 monoclonal antibodies indicated uniform labeling and that no fragmentation of the monoclonal antibodies had taken place during the labeling procedure. Immunospecificity of 186Re-labeled human neutrophil specific IgM, as determined by in vitro antigen excess assay, was comparable to that of indium-111-labeled c-DTPA-IgM and technetium-99m-labeled-IgM. A nuclear histone specific 186Re-TNT-1-F(ab')2 was evaluated in mice bearing experimental tumors. The tumor/muscle ratios at 4 and 24 hr were 5.9 +/- 0.21 and 13.8 +/- 6.7, respectively compared to that of 2.4 +/- 0.3 at 4 hr p.i. with a nonspecific protein. The labeling technique is simple, reliable and has already been adapted to a single-vial kit preparation.

  15. Induced internal electron transfer chemistry in rhenium sulfide systems

    SciTech Connect

    Murray, H.H.; Wei, L.; Sherman, S.E.; Greaney, M.A.; Eriksen, K.A.; Carstensen, B.; Halbert, T.R.; Stiefel, E.I.

    1995-02-15

    This paper demonstrates the proclivity with which high-valent rhenium sulfur complexes undergo internal electron transfer. Specifically, reaction of [Et{sub 4}N][ReS{sub 4}] with 1.5 molar equiv of tetraalkylthiuram disulfide in acetonitrile gives the dinuclear Re(IV) complexes, Re{sub 2}({mu}-S){sub 2}(S{sub 2}CNR{sub 2}), 1, in very high yield. This dimer reacts with an additional equivalent of tetraalkylthiuram disulfide in the presence of excess Lewis acids, or with 0.5 molar equiv of tetraalkylthiuram disulfide and 1 molar equiv of [Cp{sub 2}Fe][PF{sub 6}], to give the dinuclear Re(III) species [Re{sub 2}({mu}-S-S{sub 2}CNR{sub 2}){sub 2}(S{sub 2}CNR{sub 2}){sub 3}]{sup +}, 2, in high yield. The reaction of [ReS{sub 4}]{sup {minus}} with 3 molar equiv of tetraalkylthiuram disulfide in a mixture of dichloromethane and acetonitrile gives the mononuclear Re(V) species [Re(S{sub 2}CN(R){sub 2}){sub 4}]-[Cl], 3, in high yield. Each of these reactions involves induced internal electron transfer in which the formal oxidation state of the metal center is reduced by the addition of an oxidant (i.e., tetraalkylthiuram disulfide). The bound sulfide is the reductant both for the metal and the external oxidant. The reformation of 1 from 2, in which the metal is oxidized, can be effected using reductants such as H{sub 2}. Electrochemical properties and chemical reactivities of the complexes are presented.

  16. Rhenium complexes of tris(pyrazolyl)methanes and sulfonate derivative.

    PubMed

    Alegria, Elisabete C B; Martins, Luísa M D R S; Haukka, Matti; Pombeiro, Armando J L

    2006-11-07

    The trioxo [ReO(3){SO(3)C(pz)(3)}] (1) (pz = pyrazolyl) and oxo [ReOCl{SO(3)C(pz)(3)}(PPh(3))]Cl (2) compounds with tris(pyrazolyl)methanesulfonate were obtained by treatment of Re(2)O(7) or [ReOCl(3)(PPh(3))(2)], respectively, with Li[SO(3)C(pz)(3)], whereas [ReCl(3){HC(pz)(3)}] (3), [ReCl(3){HC(3,5-Me(2)pz)(3)}] (4) and [ReCl(4){eta(2)-HC(pz)(3)}] (5) were prepared by reaction of [ReOCl(3)(PPh(3))(2)] (3,4) or [ReCl(4)(NCMe)(2)] (5) with hydrotris(pyrazolyl)methane HC(pz)(3) (3,5) or hydrotris(3,5-dimethyl-1-pyrazolyl)methane HC(3,5-Me(2)pz)(3) (4). [ReO{SO(3)C(pz)(3)}{OC(CH(3))(2)pz}][ReO(4)] 6, with a chelated pyrazolyl-alkoxide, was derived from an unprecedented ketone-pyrazolyl coupling on reaction of crude 1 with acetone. The compounds have been characterized by elemental analyses, IR and NMR spectroscopies, FAB-MS spectrometry and cyclic voltammetry and, in the case of 5 and 6, also by single-crystal X-ray diffraction. The electrochemical E(L) Lever parameter has been estimated, for the first time, for the SO(3)C(pz)(3)(-) and oxo ligands allowing the measurement of their electron-donor character and comparison with other ligands. Compounds 1, 2 and 6 appear to be the first tris(pyrazolyl)methanesulfonate complexes of rhenium to be reported.

  17. Synthesis, crystal structure and magnetic properties of new indium rhenium and scandium rhenium oxides, In 6ReO 12 and Sc 6ReO 12

    NASA Astrophysics Data System (ADS)

    Mikhailova, D.; Ehrenberg, H.; Fuess, H.

    2006-12-01

    The new complex indium rhenium and scandium rhenium oxides, In 6ReO 12 and Sc 6ReO 12, have been synthesized as single phases in sealed silica tubes and by high-pressure high-temperature syntheses, and their crystal structures have been determined by single crystal X-ray diffraction.The compounds crystallize in a rhombohedral structure related to the distorted fluorite structure like Ln 6ReO 12 for some rare earth elements, S. G.: R-3, Z=3, aH= 9.248(2) Å, cH=8.720(2) Å for Sc 6ReO 12 and aH=9.492(1) Å, cH=8.933(1) Å for In 6ReO 12. A maximum in magnetization is observed for Sc 6ReO 12 at T( Mmax)=1.89(2) K, whereas ferromagnetic ordering is found for In 6ReO 12 by a pronounced increase in the temperature dependence of magnetization at TC=7.5(5) K. The magnetic moment per rhenium ion in In 6ReO 12 and Sc 6ReO 12 is 0.84(1) and 0.65(1) μB, respectively, derived from the paramagnetic regions.

  18. [Spectrophotometric study of the interaction between rhenium complexes and phosphatidylcholine during liposome formation].

    PubMed

    Shtemenko, O V; Zeleniuk, M A; Shtemenko, N I; Verbyts'ka, Ia S

    2002-01-01

    The electron absorption spectra of halogenides and halogencarboxylate complex compounds of rhenium (III) having cluster structure with phosphatydilcholine and their lyposome forms were investigated. Some results which evidence for the interaction of these compounds with phosphatydilcholine were obtained. The possible mechanism of this interaction is discussed.

  19. Unprecedented staining of polar lipids by a luminescent rhenium complex revealed by FTIR microspectroscopy in adipocytes.

    PubMed

    Bader, C A; Carter, E A; Safitri, A; Simpson, P V; Wright, P; Stagni, S; Massi, M; Lay, P A; Brooks, D A; Plush, S E

    2016-06-21

    Fourier transform infrared (FTIR) microspectroscopy and confocal imaging have been used to demonstrate that the neutral rhenium(i) tricarbonyl 1,10-phenanthroline complex bound to 4-cyanophenyltetrazolate as the ancillary ligand is able to localise in regions with high concentrations of polar lipids such as phosphatidylethanolamine (PE), sphingomyelin, sphingosphine and lysophosphatidic acid (LPA) in mammalian adipocytes.

  20. Rhenium solubility in borosilicate nuclear waste glass: implications for the processing and immobilization of technetium-99.

    PubMed

    McCloy, John S; Riley, Brian J; Goel, Ashutosh; Liezers, Martin; Schweiger, Michael J; Rodriguez, Carmen P; Hrma, Pavel; Kim, Dong-Sang; Lukens, Wayne W; Kruger, Albert A

    2012-11-20

    The immobilization of technetium-99 ((99)Tc) in a suitable host matrix has proven to be a challenging task for researchers in the nuclear waste community around the world. In this context, the present work reports on the solubility and retention of rhenium, a nonradioactive surrogate for (99)Tc, in a sodium borosilicate glass. Glasses containing target Re concentrations from 0 to 10,000 ppm [by mass, added as KReO(4) (Re(7+))] were synthesized in vacuum-sealed quartz ampules to minimize the loss of Re from volatilization during melting at 1000 °C. The rhenium was found as Re(7+) in all of the glasses as observed by X-ray absorption near-edge structure. The solubility of Re in borosilicate glasses was determined to be ~3000 ppm (by mass) using inductively coupled plasma optical emission spectroscopy. At higher rhenium concentrations, additional rhenium was retained in the glasses as crystalline inclusions of alkali perrhenates detected with X-ray diffraction. Since (99)Tc concentrations in a glass waste form are predicted to be <10 ppm (by mass), these Re results implied that the solubility should not be a limiting factor in processing radioactive wastes, assuming Tc as Tc(7+) and similarities between Re(7+) and Tc(7+) behavior in this glass system.

  1. Coating Carbon Fibers With Platinum

    NASA Technical Reports Server (NTRS)

    Effinger, Michael R.; Duncan, Peter; Coupland, Duncan; Rigali, Mark J.

    2007-01-01

    A process for coating carbon fibers with platinum has been developed. The process may also be adaptable to coating carbon fibers with other noble and refractory metals, including rhenium and iridium. The coated carbon fibers would be used as ingredients of matrix/fiber composite materials that would resist oxidation at high temperatures. The metal coats would contribute to oxidation resistance by keeping atmospheric oxygen away from fibers when cracks form in the matrices. Other processes that have been used to coat carbon fibers with metals have significant disadvantages: Metal-vapor deposition processes yield coats that are nonuniform along both the lengths and the circumferences of the fibers. The electrical resistivities of carbon fibers are too high to be compatible with electrolytic processes. Metal/organic vapor deposition entails the use of expensive starting materials, it may be necessary to use a furnace, and the starting materials and/or materials generated in the process may be hazardous. The present process does not have these disadvantages. It yields uniform, nonporous coats and is relatively inexpensive. The process can be summarized as one of pretreatment followed by electroless deposition. The process consists of the following steps: The surfaces of the fiber are activated by deposition of palladium crystallites from a solution. The surface-activated fibers are immersed in a solution that contains platinum. A reducing agent is used to supply electrons to effect a chemical reduction in situ. The chemical reduction displaces the platinum from the solution. The displaced platinum becomes deposited on the fibers. Each platinum atom that has been deposited acts as a catalytic site for the deposition of another platinum atom. Hence, the deposition process can also be characterized as autocatalytic. The thickness of the deposited metal can be tailored via the duration of immersion and the chemical activity of the solution.

  2. 2 x 2 Polyethylene Reflected and Moderated Highly Enriched Uranium System with Rhenium

    SciTech Connect

    A. Nichole Ellis; Jesson Hutchinson; John D. Bess; Dmitry N. Polyakov; Evgeny S. Glushkov; Alexey E. Glushkov

    2010-09-01

    The 2 × 2 array HEU-Re experiment was performed on the Planet universal critical assembly machine on November 4th, 2003 at the Los Alamos Critical Experiments Facility (LACEF) at Los Alamos National Laboratory (LANL). For this experiment, there were 10 ½ units, each full unit containing four HEU foils and two rhenium foils. The top unit contained only two HEU foils and two rhenium foils. A total of 42 HEU foils were used for this experiment. Rhenium is a desirable cladding material for space nuclear power applications. This experiment consisted of HEU foils interleaved with rhenium foils and is moderated and reflected by polyethylene plates. A unit consisted of a polyethylene plate, which has a recess for rhenium foils, and four HEU foils in a single layer in the top recess of each polyethylene plate. The Planet universal criticality assembly machine has been previously used in experiments containing HEU foils interspersed with SiO2 (HEU-MET-THERM-001), Al (HEU-MET-THERM-008), MgO (HEU-MET-THERM-009), Gd foils (HEU-MET-THERM-010), 2 × 2 × 26 Al (HEU-MET-THERM-012), Fe (HEU-MET-THERM-013 and HEU-MET-THERM-015), 2 × 2 × 23 SiO2 (HEU-MET-THERM-014), 2 × 2 × 11 hastalloy plates (HEU-MET-THERM-016), and concrete (HEU-MET-THERM-018). The 2 × 2 array of HEU-Re is considered acceptable for use as a benchmark critical experiment.

  3. CoMSIA and Docking Study of Rhenium Based Estrogen Receptor Ligand Analogs

    PubMed Central

    Wolohan, Peter; Reichert, David E.

    2007-01-01

    OPLS all atom force field parameters were developed in order to model a diverse set of novel rhenium based estrogen receptor ligands whose relative binding affinities (RBA) to the estrogen receptor alpha isoform (ERα) with respect to 17β-Estradiol were available. The binding properties of these novel rhenium based organometallic complexes were studied with a combination of Comparative Molecular Similarity Indices Analysis (CoMSIA) and docking. A total of 29 estrogen receptor ligands consisting of 11 rhenium complexes and 18 organic ligands were docked inside the ligand-binding domain (LBD) of ERα utilizing the program Gold. The top ranked pose was used to construct CoMSIA models from a training set of 22 of the estrogen receptor ligands which were selected at random. In addition scoring functions from the docking runs and the polar volume (PV) were also studied to investigate their ability to predict RBA ERα. A partial least-squares analysis consisting of the CoMSIA steric, electrostatic and hydrophobic indices together with the polar volume proved sufficiently predictive having a correlation coefficient, r2, of 0.94 and a cross-validated correlation coefficient, q2, utilizing the leave one out method of 0.68. Analysis of the scoring functions from Gold showed particularly poor correlation to RBA ERα which did not improve when the rhenium complexes were extracted to leave the organic ligands. The combined CoMSIA and polar volume model ranked correctly the ligands in order of increasing RBA ERα, illustrating the utility of this method as a prescreening tool in the development of novel rhenium based estrogen receptor ligands. PMID:17280694

  4. Trinuclear rhenium(III) halide clusters with carboxylate ligands

    NASA Astrophysics Data System (ADS)

    Dougan, Jeffrey Steven

    Four mono(carboxylato)trirhenium complexes and three bis(carboxylato)trirhenium complexes have been synthesized and characterized, principally by mass spectrometry, with supporting evidence from X-ray diffraction. These compounds represent the first trinuclear rhenium carboxylate complexes. The reactions generally proceed readily under comparatively mild conditions. Mass spectrometry has again proved its usefulness as a technique in the field of metal cluster chemistry, having provided the initial identification of the products of the reactions studied. These compounds provide a further base to which future mass spectra of metal cluster compounds can be compared. Re-examination of a reaction reported by Taha and Wilkinson has also cast considerable doubt onto the validity of a conversion widely reported in the literature that transforms (Re3Cl9) x into [Re2(O2CCH3)4Cl 2]. We believe that the literature result is a consequence of the purity of the metal precursor, and suggest that the starting material in the earlier work may have contained ReCl4 or ReCl5. The importance of mass spectrometry in the characterization of the new compounds synthesized in this project has led to a thorough study of calculated isotopic distributions. The information gathered suggests that for isotopically simple molecules, the choice of algorithm for computing an isotopic distribution is unimportant. However, it is important to compute the mass spectrum of an isotopically complex molecule using an algorithm that can, if desired, show the underlying isotopic fine structure of a peak of interest. In the last chapter of this thesis, the results of a project in chemistry education research are presented. Predicting the success of students in general chemistry has long been of interest to the chemistry education community, and several factors have been identified as contributing factors. An off-hand comment by a student inspired an examination of whether continuity with the same instructor for

  5. The preparation and characterization of rhenium modified Pt(111) and Pt(100), and platinum modified Re(0001) single crystal surfaces

    NASA Astrophysics Data System (ADS)

    Godbey, David J.; Somorjai, Gabor A.

    1988-08-01

    Rhenium metal grows epitaxially on Pt(111) and Pt(100) in a layer by layer mode as shown by Auger electron spectroscopy and low energy electron diffraction. The growth mode of platinum metal on Re(0001) was also found to be layer by layer. Rhenium evaporated onto Pt(111) grows with a hexagonal close-packed structure exposing the (0001) face while on Pt(100) it grows with a face centered cubic structure exposing the (100) face. The surface composition of the bimetallic Re-Pt surface can be determined from the Auger spectrum when the coverage of rhenium is less than three monolayers. Following rhenium deposition on platinum, chemical shifts were detected in the 4f levels of both adsorbate and substrate using XPS, and this is indicative of the formation of a surface alloy between the two metals. Annealing the bimetallic surface to 1150 K caused further shifts to higher binding energies for both the platinum and the rhenium 4f lines. The presence of platinum on a partially oxidized Re(0001) surface was found to catalyze the decomposition of rhenium oxides under UHV and at a temperature as low as 400° C.

  6. Application of a new composite cubic-boron nitride gasket assembly for high pressure inelastic x-ray scattering studies of carbon related materials.

    PubMed

    Wang, Lin; Yang, Wenge; Xiao, Yuming; Liu, Bingbing; Chow, Paul; Shen, Guoyin; Mao, Wendy L; Mao, Ho-kwang

    2011-07-01

    We have developed a new composite cubic-boron nitride (c-BN) gasket assembly for high pressure diamond anvil cell studies, and applied it to inelastic x-ray scattering (IXS) studies of carbon related materials in order to maintain a larger sample thickness and avoid the interference from the diamond anvils. The gap size between the two diamond anvils remained ~80 μm at 48.0 GPa with this new composite c-BN gasket assembly. The sample can be located at the center of the gap, ~20 μm away from the surface of both diamond anvils, which provides ample distance to separate the sample signal from the diamond anvils. The high pressure IXS of a solvated C(60) sample was studied up to 48 GPa, and a pressure induced bonding transition from sp(2) to sp(3) was observed at 27 GPa.

  7. Application of a new composite cubic-boron nitride gasket assembly for high pressure inelastic x-ray scattering studies of carbon related materials

    SciTech Connect

    Wang, Lin; Yang, Wenge; Xiao, Yuming; Liu, Bingbing; Chow, Paul; Shen, Guoyin; Mao, Wendy L.; Mao, Ho-kwang

    2011-01-01

    We have developed a new composite cubic-boron nitride (c-BN) gasket assembly for high pressurediamond anvil cell studies, and applied it to inelastic x-ray scattering (IXS) studies of carbon related materials in order to maintain a larger sample thickness and avoid the interference from the diamond anvils. The gap size between the two diamond anvils remained ~80 μm at 48.0 GPa with this new composite c-BN gasket assembly. The sample can be located at the center of the gap, ~20 μm away from the surface of both diamond anvils, which provides ample distance to separate the sample signal from the diamond anvils. The high pressure IXS of a solvated C₆₀ sample was studied up to 48 GPa, and a pressure induced bonding transition from sp² to sp³ was observed at 27 GPa.

  8. Recycling of waste gasket rubber granules by bulk CuCl2 and nano CuCl2: removal of Hg(II) ions by recycled rubber granules

    NASA Astrophysics Data System (ADS)

    Deivasigamani, Kalpana; Nanjan, Jayakumar; Mani, Hari Prasad

    2017-01-01

    Environmental problems arise due to the millions of tons of waste rubber that are thrown away in the natural environment. Management of this waste rubber is a big environmental challenge. So, a new, simple and cost-effective recycling method for obtaining recycled waste rubber should be developed. In this study, we found that waste gasket rubber can be desulfurized by means of bulk and nano-sized transition metal halides in the presence of solvents. The recycled product of desulfurized waste gasket rubber granules that is obtained can be used as the cheapest adsorbent in the removal of mercury(II) ions from aqueous solution. Comparative batch studies have been conducted to elucidate the adsorption efficiency of desulfurized rubber using bulk copper chloride and also using nano-sized copper chloride under optimum conditions with commercial activated carbon.

  9. The solubility of rhenium in silicate melts: Implications for the geochemical properties of rhenium at high temperatures

    NASA Astrophysics Data System (ADS)

    Ertel, W.; O'Neill, H. St. C.; Sylvester, P. J.; Dingwell, D. B.; Spettel, B.

    2001-07-01

    The solubility of rhenium (Re) in a haplobasaltic melt (anorthite-diopside eutectic composition) has been experimentally determined using the mechanically assisted equilibration technique at 1400°C as a function of oxygen fugacity (10 -12 < fO 2 ≤ 10 -7 bar), imposed by CO-CO 2 gas mixtures. Samples were analysed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). This is a true microanalytical technique, which allows small-scale sample heterogeneity to be detected, while providing a limit of detection of 2 ppb Re. Time-resolved LA-ICP-MS spectra revealed the presence of suboptically sized micronuggets of Re in all samples, which, because they are present at the 0.5 to 10 ppm level, dominate the true solubilities of Re (<1 ppm at the conditions of the experiment) in bulk analyses of the samples. Nevertheless, the micronuggets could be filtered out from the time-resolved spectra to reveal accurate values of the true Re solubility. A number of time series of samples were taken at constant fO 2 to demonstrate that the solubilities converge to a constant value. In addition, solubilities were measured after increasing and decreasing the imposed fO 2. The results show that Re dissolves in the silicate melt as ReO 2 (Re 4+) and ReO 3 (Re 6+) species, with the latter predominating at typical terrestrial upper-mantle oxygen fugacities. The total solubility of Re is described by the following expression (fO 2 in bars): [Re/ppb] = 9.7(±1.9) × 10 9 (fO 2) + 4.2 (±0.3) × 10 14 (fO 2) 1.5Assuming an activity coefficient for Re in Fe-rich metal of 1, this gives a value of D Remet/sil of 5 × 10 10 at log fO 2 = IW-2, appropriate for metal-silicate partitioning in an homogenously accreting Earth. Thus, Re is indeed very highly siderophile, and the mantle's abundance cannot be explained by homogenous accretion.

  10. Determination of polyadipates migrating from lid gaskets of glass jars. Hydrolysis to adipic acid and measurement by LC-MS/MS.

    PubMed

    Driffield, M; Bradley, E L; Harmer, N; Castle, L; Klump, S; Mottier, P

    2010-10-01

    Polyadipate plasticizers can be present in the polyvinylchloride (PVC) gaskets used to seal the lids of glass jars. As the gaskets can come into direct contact with the foodstuffs inside the jar, the potential exists for polyadipate migration into the food. The procedure and performance characteristics of a test method for the analysis of polyadipates in food simulants (3% aqueous acetic acid and 10% aqueous ethanol) and the volatile test media used in substitute fat tests (isooctane and 95% aqueous ethanol) are described. The PVC gaskets were exposed to the food simulants or their substitutes under standard test conditions. Studies were initially carried out using direct measurement of the polyadipate oligomers by liquid chromatography with time-of-flight mass spectrometric detection (LC-TOF-MS) but this was not practical due to the number of peaks detected. Instead, the migrating polyadipates were hydrolysed to adipic acid and measured by liquid chromatography with tandem mass spectrometric detection (LC-MS/MS). The amount of polyadipate that this measurement of adipic acid represents was then calculated. Method performance was assessed by analysis of gaskets from two types of jar lids by single-laboratory validation. Linearity, sensitivity, repeatability, intermediate reproducibility and recovery were determined to be suitable for checking compliance with the 30 mg/kg specific migration limits for polyesters of 1,2-propane diol and/or 1,3- and/or 1,4-butanediol and/or polypropylene-glycol with adipic acid, which may be end-capped with acetic acid or fatty acids C(12)-C(18) or n-octanol and/or n-decanol. The method was found to be much quicker than previous methods involving extraction, clean-up, hydrolysis, esterification, derivatisation and GC measurement, consequently saving time and money.

  11. A first-principles model for anomalous segregation in dilute ternary tungsten-rhenium-vacancy alloys

    NASA Astrophysics Data System (ADS)

    Wróbel, J. S.; Nguyen-Manh, D.; Kurzydłowski, K. J.; Dudarev, S. L.

    2017-04-01

    The occurrence of segregation in dilute alloys under irradiation is a highly unusual phenomenon that has recently attracted attention, stimulated by the interest in the fundamental properties of alloys as well as by their applications. The fact that solute atoms segregate in alloys that, according to equilibrium thermodynamics, should exhibit full solubility, has significant practical implications, as the formation of precipitates strongly affects physical and mechanical properties of alloys. A lattice Hamiltonian, generalizing the so-called ‘ABV’ Ising model and including collective many-body inter-atomic interactions, has been developed to treat rhenium solute atoms and vacancies in tungsten as components of a ternary alloy. The phase stability of W-Re-vacancy alloys is assessed using a combination of density functional theory (DFT) calculations and cluster expansion (CE) simulations. The accuracy of CE parametrization is evaluated against the DFT data, and the cross-validation error is found to be less than 4.2 meV/atom. The free energy of W-Re-vacancy ternary alloys is computed as a function of temperature using quasi-canonical Monte Carlo simulations, using effective two, three and four-body interactions. In the low rhenium concentration range (<5 at. % Re), solute segregation is found to occur in the form of voids decorated by Re atoms. These vacancy-rhenium clusters remain stable over a broad temperature range from 800 K to 1600 K. At lower temperatures, simulations predict the formation of Re-rich rhenium-vacancy clusters taking the form of sponge-like configurations that contain from 30 to 50 at. % Re. The anomalous vacancy-mediated segregation of Re atoms in W can be rationalized by analyzing binding energy dependence as a function of Re to vacancy ratio as well as chemical Re-W and Re-vacancy interactions and short-range order parameters. DFT calculations show that rhenium-vacancy binding energies can be as high as 1.5 eV if the rhenium

  12. A first-principles model for anomalous segregation in dilute ternary tungsten-rhenium-vacancy alloys.

    PubMed

    Wróbel, J S; Nguyen-Manh, D; Kurzydłowski, K J; Dudarev, S L

    2017-04-12

    The occurrence of segregation in dilute alloys under irradiation is a highly unusual phenomenon that has recently attracted attention, stimulated by the interest in the fundamental properties of alloys as well as by their applications. The fact that solute atoms segregate in alloys that, according to equilibrium thermodynamics, should exhibit full solubility, has significant practical implications, as the formation of precipitates strongly affects physical and mechanical properties of alloys. A lattice Hamiltonian, generalizing the so-called 'ABV' Ising model and including collective many-body inter-atomic interactions, has been developed to treat rhenium solute atoms and vacancies in tungsten as components of a ternary alloy. The phase stability of W-Re-vacancy alloys is assessed using a combination of density functional theory (DFT) calculations and cluster expansion (CE) simulations. The accuracy of CE parametrization is evaluated against the DFT data, and the cross-validation error is found to be less than 4.2 meV/atom. The free energy of W-Re-vacancy ternary alloys is computed as a function of temperature using quasi-canonical Monte Carlo simulations, using effective two, three and four-body interactions. In the low rhenium concentration range (<5 at.[Formula: see text]Re), solute segregation is found to occur in the form of voids decorated by Re atoms. These vacancy-rhenium clusters remain stable over a broad temperature range from 800 K to 1600 K. At lower temperatures, simulations predict the formation of Re-rich rhenium-vacancy clusters taking the form of sponge-like configurations that contain from 30 to 50 at.[Formula: see text]Re. The anomalous vacancy-mediated segregation of Re atoms in W can be rationalized by analyzing binding energy dependence as a function of Re to vacancy ratio as well as chemical Re-W and Re-vacancy interactions and short-range order parameters. DFT calculations show that rhenium-vacancy binding energies can be as high as 1

  13. Multiresidual LC-MS analysis of plasticizers used in PVC gaskets of lids and assessment of their migration into food sauces.

    PubMed

    Lambertini, F; Catellani, D; Vindigni, M; Suman, M

    2016-09-01

    Plasticizers may migrate from polyvinyl chloride (PVC) gaskets into the foodstuffs mainly by direct contact during the packaging and sterilization procedure, but also by means of occasional contacts occurring during shipment and storage. The present work reports a reliable liquid chromatography-mass spectrometry (LC-MS) method able to quantify the main plasticizers used in the PVC closure gaskets for metal lids to verify their compliance in both food contact materials and foodstuffs. The atmospheric pressure chemical ionization in the positive ion mode resulted the best performing interface for the multiresidual detection of the plasticizers taken into account, followed by selected/multiple reaction monitoring, selected ion monitoring or full scan experiments, depending on the compounds to detect. The method was single-laboratory validated, demonstrating to reach a good sensitivity, thus making possible to perform analysis without any preliminary sample purification or concentration step. It proved to be effectively applicable not only for the determination of plasticizers in PVC gaskets but also in complex food matrices. In particular, it was applied for monitoring plasticizer migration into sauces placed in contact with the lids in worst storage conditions, observing therefore their trend during the shelf-life. Copyright © 2016 John Wiley & Sons, Ltd.

  14. Development and turbine engine performance of three advanced rhenium containing superalloys for single crystal and directionally solidified blades and vanes

    SciTech Connect

    Broomfield, R.W.; Ford, D.A.; Bhangu, J.K.; Thomas, M.C.; Frasier, D.J.; Burkholder, P.S.; Harris, K.; Erickson, G.L.; Wahl, J.B.

    1998-07-01

    Turbine inlet temperatures over the next few years will approach 1,650 C (3,000 F) at maximum power for the latest large commercial turbofan engines, resulting in high fuel efficiency and thrust levels approaching 445 kN (100,000 lbs). High reliability and durability must be intrinsically designed into these turbine engines to meet operating economic targets and ETOPS certification requirements. This level of performance has been brought about by a combination of advances in air cooling for turbine blades and vanes, design technology for stresses and airflow, single crystal and directionally solidified casting process improvements, and the development and use of rhenium (Re) containing high {gamma}{prime} volume fraction nickel-base superalloys with advanced coatings, including full-airfoil ceramic thermal barrier coatings. Re additions to cast airfoil superalloys not only improves creep and thermo-mechanical fatigue strength, but also environmental properties including coating performance. Re dramatically slows down diffusion in these alloys at high operating temperatures. A team approach has been used to develop a family of two nickel-base single crystal alloys (CMSX-4 containing 3% Re and CMSX-10 containing 6% Re) and a directionally solidified, columnar grain nickel-base alloy (CM 186 LC containing 3% Re) for a variety of turbine engine applications. A range of critical properties of these alloys is reviewed in relation to turbine component engineering performance through engine certification testing and service experience. Industrial turbines are now commencing to use this aero developed turbine technology in both small and large frame units in addition to aero-derivative industrial engines. These applications are demanding, with high reliability required for turbine airfoils out to 25,000 hours, with perhaps greater than 50% of the time spent at maximum power. Combined cycle efficiencies of large frame industrial engines are scheduled to reach 60% in the US

  15. Liquid extraction of rhenium(VII) and molybdenum(VI) with trialkylphosphine oxide from acidic solutions

    NASA Astrophysics Data System (ADS)

    Travkin, V. F.; Palant, A. A.

    2012-01-01

    The liquid extraction of rhenium(VII) and molybdenum(VI) ions from sulfuric, hydrochloric, and nitric acid media is studied in the temperature range from 20 to 40°C using trialkylphosphine oxide in kerosene as an extracting agent. The maximum separation of these metals is attained when they are extracted from solutions of 1.0-2.0 M H2SO4 (the duration of intense phase mixing was 3-5 min). The enthalpy of the studied process is estimated to be Δ H = -32.32 kJ/mol for molybdenum and -51.52 kJ/mol for rhenium. The chemical aspects of the extraction process studied are discussed.

  16. Crystallization and rhenium MAD phasing of the acyl-homoserinelactone synthase EsaI

    SciTech Connect

    Watson, W.T.; Murphy IV, Frank V.; Gould, Ty A.; Jambeck, Per; Val, Dale L.; Cronan, Jr., John E.; Beck von Bodman, Susan; Churchill, Mair E.A.

    2009-04-22

    Acyl-homoserine-L-lactones (AHLs) are diffusible chemical signals that are required for virulence of many Gram-negative bacteria. AHLs are produced by AHL synthases from two substrates, S-adenosyl-L-methionine and acyl-acyl carrier protein. The AHL synthase EsaI, which is homologous to the AHL synthases from other pathogenic bacterial species, has been crystallized in the primitive tetragonal space group P4{sub 3}, with unit-cell parameters a = b = 66.40, c = 47.33 {angstrom}. The structure was solved by multiple-wavelength anomalous diffraction with a novel use of the rhenium anomalous signal. The rhenium-containing structure has been refined to a resolution of 2.5 {angstrom} and the perrhenate ion binding sites and liganding residues have been identified.

  17. Rhenium-osmium-isotope constraints on the age of iron meteorites

    NASA Technical Reports Server (NTRS)

    Horan, M. F.; Morgan, J. W.; Walker, R. J.; Grossman, J. N.

    1992-01-01

    Rhenium and osmium concentrations and the osmium isotopic compositions of iron meteorites were determined by negative thermal ionization mass spectrometry. Data for the IIA iron meteorites define an isochron with an uncertainty of approximately +/-31 million years for meteorites about 4500 million years old. Although an absolute rhenium-osmium closure age for this iron group cannot be as precisely constrained because of uncertainty in the decay constant of Re-187, an age of 4460 million years ago is the minimum permitted by combined uncertainties. These age constraints imply that the parent body of the IIAB magmatic irons melted and subsequently cooled within 100 million years after the formation of the oldest portions of chondrites. Other iron meteorites plot above the IIA isochron, indicating that the planetary bodies represented by these iron groups may have cooled significantly later than the parent body of the IIA irons.

  18. Alkoxy bridged binuclear rhenium (I) complexes as a potential sensor for β-amyloid aggregation.

    PubMed

    Sathish, Veerasamy; Babu, Eththilu; Ramdass, Arumugam; Lu, Zong-Zhan; Velayudham, Murugesan; Thanasekaran, Pounraj; Lu, Kuang-Lieh; Rajagopal, Seenivasan

    2014-12-01

    Alkoxy bridged binuclear rhenium(I) complexes are used as a probe for the selective and sensitive detection of aggregation of β-amyloid fibrils that are consorted with Alzheimer's disease (AD). The strong binding of the complexes is affirmed by the fluorescence enhancement and calculated binding constant value in the order of 10(5)M(-1) is obtained from the Scatchard plots. The binding of β-amyloid can be attributed to π-π stacking interaction of naphthalene moiety present in rhenium(I) complexes, and it is supported by docking studies. The selectivity is quite high towards other proteins and the formation of fibrils can be observed in the range of 30-40 nm through the AFM and TEM techniques. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Slip casting and extruding shapes of rhenium with metal oxide additives. 1: Feasibility demonstration

    NASA Technical Reports Server (NTRS)

    Barr, F. A.; Page, R. J.

    1986-01-01

    The feasibility of fabricating small rhenium parts with metal oxide additives by means of slip casting and extrusion techniques is described. The metal oxides, ZrO2 and HfO2 were stabilized into the cubic phase with Y2O3. Additions of metal oxide to the rhenium of up to 15 weight percent were used. Tubes of 17 mm diameter with 0.5 mm walls were slip cast by adapting current ceramic oxide techniques. A complete cast double conical nozzle demonstrated the ability to meet shapes and tolerances. Extrusion of meter long tubing lengths of 3.9 mm o.d. x 2.3 mm i.d. final dimension is documented. Sintering schedules are presented to produce better than 95% of theoretical density parts. Finished machining was found possible were requried by electric discharge machining and diamond grinding.

  20. The process development of laser surface modification of commercially pure titanium (Grade 2) with rhenium

    NASA Astrophysics Data System (ADS)

    Kobiela, K.; Smolina, I.; Dziedzic, R.; Szymczyk, P.; Kurzynowski, T.; Chlebus, E.

    2016-12-01

    The paper presents the results of the process development of laser surface modification of commercially pure titanium with rhenium. The criterion of the successful/optimal process is the repetitive geometry of the surface, characterized by predictable and repetitive chemical composition over its entire surface as well as special mechanical properties (hardness and wear resistance). The analysis of surface geometry concluded measurements of laser penetration depth and heat affected zone (HAZ), the width of a single track as well as width of a clad. The diode laser installed on the industrial robot carried out the laser treatment. This solution made possible the continuous supply of powder to the substrate during the process. The aim of an investigation is find out the possibility of improving the tribological characteristics of the surface due to the rhenium alloying. The verification of the surface properties (tribological) concluded geometry measurements, microstructure observation, hardness tests and evaluation of wear resistance.

  1. Production and investigation into properties of high-pure rhenium fluorides

    NASA Astrophysics Data System (ADS)

    Vybyvanets, V. I.; Kosukhin, A. V.; Cherenkov, A. V.; Shilkin, G. S.

    2016-01-01

    Two products of synthesis were obtained: synthesis product at a fluorination temperature of 300°C, synthesis product at a fluorination temperature of 600°C. Two source products were separated and rectified during this work. Monofraction of rhenium hexafluorides and heptafluorides were obtained. The temperatures of liquids in the system ReF6 - ReF7 were determined. Liquid-vapor equilibrium in the system was investigated. Viscosity and surface-tension at the liquid-to-vapor boundary are measured for liquid ReF6 and ReF7.A promising method of tungsten-rhenium alloys making is a gas-phase precipitation, namely joint hydrogen reduction of these metals fluorides.

  2. Equations for determining CVD tungsten-rhenium alloy composition and plating rate

    SciTech Connect

    Klingsporn, P.E.

    1987-04-01

    The composition and plating rate of CVD tungsten-rhenium alloy, formed by hydrogen reduction of a tungsten and rhenium metal hexafluoride gas mixture on a heated substrate, depend on the substrate temperature, hydrogen gas flow, metal fluoride gas flow, and the pressure. An equation was derived that allows the alloy composition to be calculated for any combination of the variables, based on the measured composition for one set of the variables. Also, equations were derived from which the W-Re alloy plating rate can be calculated in terms of the measured rate and composition at one set of the variables, or, in terms of the measured rates at two sets of the variables, without knowledge of the composition. W-Re alloy compositions and plating rates calculated with the equations were compared with experimental data.

  3. Large enhancement of superconducting transition temperature in single-element superconducting rhenium by shear strain

    NASA Astrophysics Data System (ADS)

    Mito, Masaki; Matsui, Hideaki; Tsuruta, Kazuki; Yamaguchi, Tomiko; Nakamura, Kazuma; Deguchi, Hiroyuki; Shirakawa, Naoki; Adachi, Hiroki; Yamasaki, Tohru; Iwaoka, Hideaki; Ikoma, Yoshifumi; Horita, Zenji

    2016-11-01

    Finding a physical approach for increasing the superconducting transition temperature (Tc) is a challenge in the field of material science. Shear strain effects on the superconductivity of rhenium were investigated using magnetic measurements, X-ray diffraction, transmission electron microscopy, and first-principles calculations. A large shear strain reduces the grain size and simultaneously expands the unit cells, resulting in an increase in Tc. Here we show that this shear strain approach is a new method for enhancing Tc and differs from that using hydrostatic strain. The enhancement of Tc is explained by an increase in net electron–electron coupling rather than a change in the density of states near the Fermi level. The shear strain effect in rhenium could be a successful example of manipulating Bardeen–Cooper–Schrieffer-type Cooper pairing, in which the unit cell volumes are indeed a key parameter.

  4. Rhenium-osmium isotope constraints on the age of iron meteorites

    USGS Publications Warehouse

    Horan, M.F.; Morgan, J.W.; Walker, R.J.; Grossman, J.N.

    1992-01-01

    Rhenium and osmium concentrations and the osmium isotopic compositions of iron meteorites were determined by negative thermal ionization mass spectrometry. Data for the IIA iron meteorites define an isochron with an uncertainty of approximately ??31 million years for meteorites ???4500 million years old. Although an absolute rhenium-osmium closure age for this iron group cannot be as precisely constrained because of uncertainty in the decay constant of 187Re, an age of 4460 million years ago is the minimum permitted by combined uncertainties. These age constraints imply that the parent body of the IIAB magmatic irons melted and subsequently cooled within 100 million years after the formation of the oldest portions of chondrites. Other iron meteorites plot above the IIA isochron, indicating that the planetary bodies represented by these iron groups may have cooled significantly later than the parent body of the IIA irons.

  5. Electrotransport and diffusivity of molybdenum, rhenium, tungsten, and zirconium in beta-thorium

    NASA Technical Reports Server (NTRS)

    Schmidt, F. A.; Beck, M. S.; Rehbein, D. K.; Conzemius, R. J.; Carlson, O. N.

    1984-01-01

    The electric mobilities, diffusivities, and effective valences were determined for molybdenum, rhenium, tungsten, and zirconium in beta-thorium. All four solutes migrated in the same direction as the electron flow. Rhenium and molybdenum were found to be very mobile, with tungsten somewhat slower. Zirconium was found to move at a rate near that of the self-diffusion of beta-thorium, viz., about 10 to the -11th sq m/s at 1500 C. The electromigration velocities showed a similar trend. A comparison was made between experimental data obtained by scanning laser mass spectrometry and theoretical transport equations for two purification experiments. Good agreement was obtained with both the concentration profile predicted by DeGroot and the purification ratio predicted by Verhoeven.

  6. Large enhancement of superconducting transition temperature in single-element superconducting rhenium by shear strain.

    PubMed

    Mito, Masaki; Matsui, Hideaki; Tsuruta, Kazuki; Yamaguchi, Tomiko; Nakamura, Kazuma; Deguchi, Hiroyuki; Shirakawa, Naoki; Adachi, Hiroki; Yamasaki, Tohru; Iwaoka, Hideaki; Ikoma, Yoshifumi; Horita, Zenji

    2016-11-04

    Finding a physical approach for increasing the superconducting transition temperature (Tc) is a challenge in the field of material science. Shear strain effects on the superconductivity of rhenium were investigated using magnetic measurements, X-ray diffraction, transmission electron microscopy, and first-principles calculations. A large shear strain reduces the grain size and simultaneously expands the unit cells, resulting in an increase in Tc. Here we show that this shear strain approach is a new method for enhancing Tc and differs from that using hydrostatic strain. The enhancement of Tc is explained by an increase in net electron-electron coupling rather than a change in the density of states near the Fermi level. The shear strain effect in rhenium could be a successful example of manipulating Bardeen-Cooper-Schrieffer-type Cooper pairing, in which the unit cell volumes are indeed a key parameter.

  7. Large enhancement of superconducting transition temperature in single-element superconducting rhenium by shear strain

    PubMed Central

    Mito, Masaki; Matsui, Hideaki; Tsuruta, Kazuki; Yamaguchi, Tomiko; Nakamura, Kazuma; Deguchi, Hiroyuki; Shirakawa, Naoki; Adachi, Hiroki; Yamasaki, Tohru; Iwaoka, Hideaki; Ikoma, Yoshifumi; Horita, Zenji

    2016-01-01

    Finding a physical approach for increasing the superconducting transition temperature (Tc) is a challenge in the field of material science. Shear strain effects on the superconductivity of rhenium were investigated using magnetic measurements, X-ray diffraction, transmission electron microscopy, and first-principles calculations. A large shear strain reduces the grain size and simultaneously expands the unit cells, resulting in an increase in Tc. Here we show that this shear strain approach is a new method for enhancing Tc and differs from that using hydrostatic strain. The enhancement of Tc is explained by an increase in net electron–electron coupling rather than a change in the density of states near the Fermi level. The shear strain effect in rhenium could be a successful example of manipulating Bardeen–Cooper–Schrieffer-type Cooper pairing, in which the unit cell volumes are indeed a key parameter. PMID:27811983

  8. Electrotransport and diffusivity of molybdenum, rhenium, tungsten, and zirconium in beta-thorium

    NASA Technical Reports Server (NTRS)

    Schmidt, F. A.; Beck, M. S.; Rehbein, D. K.; Conzemius, R. J.; Carlson, O. N.

    1984-01-01

    The electric mobilities, diffusivities, and effective valences were determined for molybdenum, rhenium, tungsten, and zirconium in beta-thorium. All four solutes migrated in the same direction as the electron flow. Rhenium and molybdenum were found to be very mobile, with tungsten somewhat slower. Zirconium was found to move at a rate near that of the self-diffusion of beta-thorium, viz., about 10 to the -11th sq m/s at 1500 C. The electromigration velocities showed a similar trend. A comparison was made between experimental data obtained by scanning laser mass spectrometry and theoretical transport equations for two purification experiments. Good agreement was obtained with both the concentration profile predicted by DeGroot and the purification ratio predicted by Verhoeven.

  9. Rhenium-osmium-isotope constraints on the age of iron meteorites

    NASA Technical Reports Server (NTRS)

    Horan, M. F.; Morgan, J. W.; Walker, R. J.; Grossman, J. N.

    1992-01-01

    Rhenium and osmium concentrations and the osmium isotopic compositions of iron meteorites were determined by negative thermal ionization mass spectrometry. Data for the IIA iron meteorites define an isochron with an uncertainty of approximately +/-31 million years for meteorites about 4500 million years old. Although an absolute rhenium-osmium closure age for this iron group cannot be as precisely constrained because of uncertainty in the decay constant of Re-187, an age of 4460 million years ago is the minimum permitted by combined uncertainties. These age constraints imply that the parent body of the IIAB magmatic irons melted and subsequently cooled within 100 million years after the formation of the oldest portions of chondrites. Other iron meteorites plot above the IIA isochron, indicating that the planetary bodies represented by these iron groups may have cooled significantly later than the parent body of the IIA irons.

  10. Rhenium Solubility in Borosilicate Nuclear Waste Glass: Implications for the Processing and Immobilization of Technetium-99

    SciTech Connect

    McCloy, John S.; Riley, Brian J.; Goel, Ashutosh; Liezers, Martin; Schweiger, Michael J.; Rodriguez, Carmen P.; Hrma, Pavel R.; Kim, Dong-Sang; Lukens, Wayne W.; Kruger, Albert A.

    2012-10-26

    The immobilization of 99Tc in a suitable host matrix has proved to be an arduous task for the researchers in nuclear waste community around the world. At the Hanford site in Washington State, the total amount of 99Tc in low-activity waste (LAW) is ~1300 kg and the current strategy is to immobilize the 99Tc in borosilicate glass with vitrification. In this context, the present article reports on the solubility/retention of rhenium, a nonradioactive surrogate for 99Tc, in a LAW borosilicate glass. Due to the radioactive nature of technetium, rhenium was chosen as a simulant because of the similarity between their ionic radii and other chemical aspects. The glasses containing Re (0 – 10,000 ppm by mass) were synthesized in vacuum-sealed quartz ampoules in order to minimize the loss of Re by volatilization during melting at 1000 °C. The rhenium was found to predominantly exist as Re (VII) in all the glasses as observed by X-ray absorption near-edge structure (XANES). The solubility of Re in borosilicate glasses was determined to be ~3000 ppm (by mass) with inductively coupled plasma-optical emission spectroscopy (ICP-OES). At higher rhenium concentrations, some additional material was retained in the glasses in the form of crystalline inclusions that were detected by X-ray diffraction (XRD) and laser ablation-ICP mass spectrometry (LA-ICP-MS). The implications of these results on the immobilization of 99Tc from radioactive wastes in borosilicate glasses have been discussed.

  11. Sulfur-bonded thiophenes in organometallic rhenium complexes and adsorption of isocyanides on gold

    SciTech Connect

    Robertson, Mitchell Joe

    1993-08-01

    This dissertation contains results of research conducted in two different areas: (1) organometallic synthesis and reactivity, and (2) organometallic surface chemistry. In the synthesis and reactivity studies, sulfur coordination of thiophene and benzo[b]thiophene to the metal center in organometallic rhenium complexes is examined. In the surface chemistry studies, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is used to analyze the adsorption of several isocyanides on the surface of gold powder. Results are compared and contrasted to known organometallic chemistry.

  12. Technetium and rhenium pentacarbonyl complexes with C₂ and C₁₁ ω-isocyanocarboxylic acid esters.

    PubMed

    Miroslavov, Alexander E; Polotskii, Yuriy S; Gurzhiy, Vladislav V; Ivanov, Alexander Yu; Lumpov, Alexander A; Tyupina, Margarita Yu; Sidorenko, Georgy V; Tolstoy, Peter M; Maltsev, Daniil A; Suglobov, Dmitry N

    2014-08-04

    Technetium(I) and rhenium(I) pentacarbonyl complexes with ethyl 2-isocyanoacetate and methyl 11-isocyanoundecanoate, [M(CO)5(CNCH2COOEt)]ClO4 (M = Tc (1) and Re (2)) and [M(CO)5(CN(CH2)10COOMe)]ClO4 (M = Tc (3) and Re (4)), were prepared and characterized by IR, (1)H NMR, and (13)C{(1)H} NMR spectroscopy. The crystal structures of 1 and 2 were determined using single-crystal X-ray diffraction. The kinetics of thermal decarbonylation of technetium complexes 1 and 3 in ethylene glycol was studied by IR spectroscopy. The rate constants and activation parameters of this reaction were determined and compared with those for [Tc(CO)6](+). It was found that rhenium complexes 2 and 4 were stable with respect to thermal decarbonylation. Histidine challenge reaction of complexes 1 and 2 in phosphate buffer was examined by IR spectroscopy. In the presence of histidine, the rhenium pentacarbonyl isocyanide complex partially decomposes to form an unidentified yellow precipitate. Technetium analogue 1 is more stable under these conditions.

  13. Applied radioactivity in radiation synovectomy with [188Re]rhenium sulfide suspension.

    PubMed

    Li, Peiyong; Yu, Junfeng; Chen, Gang; Jiang, Xufeng; Tang, Zhonghua; Chen, Suyun; Jiang, Lei; Tang, Lin; Yin, Duanzhi

    2006-08-01

    Early experience demonstrated absorbed dose in radiation synovectomy is about 100 Gy. For reaching this dose, the applied radioactivity should be calculated. Twenty-nine synovitic models of rabbit were treated by intra-articular injection of [(188)Re]rhenium sulfide and histological changes of synovium and cartilage were examined. The applied radioactivity was calculated by method of absorbed dose factor. In clinical, eleven haemophilic patients with haemarthrosis were performed radiation synovectomy with treated [(188)Re]rhenium sulfide. The synovial thickness was evaluated by MR and its value was used to calculate the applied radioactivity. After radiation synovectomy, all patients were followed up by synovial thickness, regional inflammation, and clinical course including bleeding frequency. In rabbit models, the synovitic membrane can be eliminated by calculated radioactivity as planed without damaging the joint cartilage. In patients study, all patients exhibited significant reductions in synovial thickness and inflammation after radiation synovectomy with the planed radioactivities of [(188)Re]rhenium sulfide. Post-procedure bleeding frequency reduction in excellent and good reached to 63.6% by 18 months. In the cases of joint bleeding, the need for antihaemophilic factor treatment decreased immensely. Most of the recurrent episodes of bleeding were mild, subsiding with local means. The applied radioactivity in radiation synovectomy could be calculated according to thickness of inflamed synovium. Further study including comparison therapeutic results from calculated individual activities with results from fixed activities and long-term follow-up is warranted.

  14. Characterization of rhenium compounds obtained by electrochemical synthesis after aging process

    SciTech Connect

    Vargas-Uscategui, Alejandro; Mosquera, Edgar; López-Encarnación, Juan M.; Chornik, Boris; Katiyar, Ram S.; Cifuentes, Luis

    2014-12-15

    The proper identification of the molecular nature of the aged rhenium compound obtained by means of electrodeposition from an alkaline aqueous electrolyte was determined. Chemical, structural and vibrational experimental characterization of the aged Re compound showed agreement with quantum-computations, thereby allowing the unambiguous identification of the Re compound as H(ReO{sub 4})H{sub 2}O. - Graphical abstract: Rhenium oxides were electrodeposited on a copper surface and after environmental aging was formed the H(ReO{sub 4})H{sub 2}O compound. The characterization of the synthesized material was made through the comparison of experimental evidence with quantum mechanical computations carried out by means of density functional theory (DFT). - Highlights: • Aged rhenium compound obtained by means of electrodeposition was studied. • The study was made by combining experimental and DFT-computational information. • The aged electrodeposited material is consistent with the H(ReO{sub 4})H{sub 2}O compound.

  15. Negative Impact of Total Body Irradiation on the Antitumor Activity of Rhenium-(I)-diselenoether.

    PubMed

    Collery, Philippe; Santoni, Francois; Mohsen, Ahmed; Mignard, Caroline; Desmaele, Didier

    2016-11-01

    It has been shown that a rhenium-(I)-diselenoether complex had significant antitumor activity in MDA-MB231 tumor-bearing mice after repeated oral or intraperitoneal administrations for 4 weeks at safe doses of 10 mg/kg/day. It has also been suggested that lower doses could be as effective as this dose. We, thus, tested two doses (5 and 10 mg/kg). The drug was orally administered daily by gavage for 4 weeks and for a further 2 weeks with or without 15 mg/kg paclitaxel treatment (intravenously, once a week). This experiment was performed in MDA-MB 231 tumor-bearing mice, as a model of resistant breast tumor. However, in contrast to previous studies, the mice were pretreated with total body irradiation to increase the tumor growth. These two doses were safe, even in combination with paclitaxel. The expected tumor regression was not observed with the rhenium-(I)-diselenoether complex, and there was even a significant increase of the tumor volume in mice treated with 10 mg/kg versus controls. No synergism was observed with paclitaxel. We comment on the possible negative impact of radiotherapy on the antitumor activity of the drug. Plasma and tumor rhenium and selenium concentrations are also reported. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  16. Mono- and Dinuclear Phosphorescent Rhenium(I) Complexes: Impact of Subcellular Localization on Anticancer Mechanisms.

    PubMed

    Ye, Rui-Rong; Tan, Cai-Ping; Chen, Mu-He; Hao, Liang; Ji, Liang-Nian; Mao, Zong-Wan

    2016-06-01

    Elucidation of relationship among chemical structure, cellular uptake, localization, and biological activity of anticancer metal complexes is important for the understanding of their mechanisms of action. Organometallic rhenium(I) tricarbonyl compounds have emerged as potential multifunctional anticancer drug candidates that can integrate therapeutic and imaging capabilities in a single molecule. Herein, two mononuclear phosphorescent rhenium(I) complexes (Re1 and Re2), along with their corresponding dinuclear complexes (Re3 and Re4), were designed and synthesized as potent anticancer agents. The subcellular accumulation of Re1-Re4 was conveniently analyzed by confocal microscopy in situ in live cells by utilizing their intrinsic phosphorescence. We found that increased lipophilicity of the bidentate ligands could enhance their cellular uptake, leading to improved anticancer efficacy. The dinuclear complexes were more potent than the mononuclear counterparts. The molecular anticancer mechanisms of action evoked by Re3 and Re4 were explored in detail. Re3 with a lower lipophilicity localizes to lysosomes and induces caspase-independent apoptosis, whereas Re4 with higher lipophilicity specially accumulates in mitochondria and induces caspase-independent paraptosis in cancer cells. Our study demonstrates that subcellular localization is crucial for the anticancer mechanisms of these phosphorescent rhenium(I) complexes.

  17. Evaluation of oxide dispersion strengthened (ODS) molybdenum and molybdenum-rhenium Alloys

    SciTech Connect

    Mueller, A.J.; Bianco, R.; Buckman, R.W. Jr.

    1999-10-22

    Oxide dispersion strengthened (ODS) molybdenum alloys being developed for high temperature applications possess excellent high temperature strength and creep resistance. In addition they exhibit a ductile-to-brittle transition temperature (DBIT) in the worked and stress-relieved condition under longitudinal tensile load well below room temperature. However, in the recrystallized condition, the DBTT maybe near or above room temperature, depending on the volume fraction of oxide dispersion and the amount of prior work. Dilute rhenium additions (7 and 14 wt.%) to ODS molybdenum were evaluated to determine their effect on low temperature ductility. The addition of 7 wt.% rhenium to the ODS molybdenum did not significantly enhance the mechanical properties. However, the addition of 14 wt.% rhenium to the ODS molybdenum resulted in a DBTT well below room temperature in both the stress-relieved and recrystallized condition. Additionally, the tensile strength of ODS Mo-14Re is greater than the base ODS molybdenum at 1,000 to 1,250 C.

  18. The Metal or the Ligand? The Preferred Locus for Redox Changes in Oxygen Atom Transfer Reactions of Rhenium Amidodiphenoxides.

    PubMed

    Hoffman, Justin M; Oliver, Allen G; Brown, Seth Nathaniel

    2017-03-03

    The rhenium(V) oxo complex oxo(triphenylphosphine)(bis(3,5-di-tert-butyl-2-phenoxo)amido)rhenium(V), (ONO(Cat))ReO(PPh3), reacts with molecular oxygen to give triphenylphosphine oxide and the dimeric rhenium(VII) complex fac,anti-(ONO(Cat))Re(O)(μ-O)2Re(O)(ONO(Cat)). The ONO ligand adopts an unusual fac geometry, presumably to maximize π donation to rhenium; strong π donation is substantiated by the intraligand bond distances (metrical oxidation state = -2.24(9)). Addition of the N-heterocyclic carbene ligand IMes to fac,anti-(ONO(Cat))Re(O)(μ-O)2Re(O)(ONO(Cat)) cleaves the dimer into monomeric C1-symmetric fac-(ONO(Cat))ReO2(IMes). The monorhenium(VII) complex is deoxygenated by PMe2Ph to give the rhenium(V) compound (ONO(Cat))ReO(IMes), which can be independently prepared by ligand substitution of (ONO(Cat))ReO(PPh3). The degree of stereochemical rigidity exhibited by the dioxo compound, as established by dynamic NMR spectroscopy, excludes the intermediacy of mer-(ONO(Q))Re(V)O2(IMes) in this oxygen atom transfer reaction. Thus, oxygen atom transfer takes place preferentially by direct reduction of the oxorhenium(VII) moiety (classical oxygen atom transfer) rather than through initial internal electron transfer and ligand-centered reduction of an oxorhenium(V)-iminoquinone.

  19. In house development of (99m)Tc-Rhenium sulfide colloidal nanoparticles for sentinel lymph node detection.

    PubMed

    Dar, Ume-Kalsoom; Khan, Irfanullah; Javed, Muhammad; Ali, Muhammad; Hyder, Syed Waqar; Murad, Sohail; Anwar, Jamil

    2013-03-01

    In this study, rhenium sulfide colloidal nanoparticles were developed as radiopharmaceutical for sentinel lymph node detection. We directly used rhenium sulfide as a starting material for the preparation of colloidal nanoparticles. UV-visible spectrophotometry was used for characterization of in house developed colloidal particles. The size distribution of radioactive particles was studied by using membrane filtration method. The percentage of radiolabeled colloidal nanoparticles was determined by paper chromatography (PC). The study also includes in vitro stability, protein binding in human blood and bioevaluation in a rabbit model. The results indicate that 77.27 ± 3.26 % particles of size less than 20nm (suitable for lymphoscintigraphy) were radiolabeled. (99m)Tc labeled rhenium sulfide labeling efficacy with the radiometal is 98.5 ± 0.5%, which remains considerably stable beyond 5h at room temperature. Furthermore, it was observed that 70.2 ± 1.3% radiolabeled colloid complex showed binding with the blood protein. Bioevaluation results show the remarkable achievement of our radiopharmaceutical. The in house prepared (99m)Tc labeled rhenium sulfide colloidal nanoparticles reached the sentinel node within 15 min of post injection. These results indicate that (99m)Tc labeled rhenium sulfide colloid nanoparticles kit produced by a novel procedure seems of significant potential as a feasible candidate for further development to be used in clinical practice.

  20. Properties and Corrosion Performance of Self-reinforced Composite PEEK for Proposed Use as a Modular Taper Gasket.

    PubMed

    Ouellette, Eric S; Gilbert, Jeremy L

    2016-11-01

    bulk PEEK (modulus = 5.0 ± 0.3 GPa, 2.8 ± 0.1 GPa, respectively, p < 0.001) and higher crystallinity to bulk PEEK (44.2% ± 3%, 39.5% ± 0.5%, respectively, p = 0.039), but had comparable crystalline orientation as compared with the initial PEEK fibers. SRC-PEEK reduced fretting currents compared with metal-on-metal controls by two to three orders of magnitude in both variable load (4.0E-5 ± 3.8E-5 μA versus 2.9E-3 ± 7.1E-4 μA, respectively, p = 0.018) and variable potential (7.5E-6 ± 4.7E-6 μA versus 5.3E-3 ± 1.4E-3 μA, respectively, p = 0.022) fretting corrosion testing. Minimal damage was observed on surfaces insulated with SRC-PEEK, whereas control surfaces showed considerable fretting corrosion damage and metal transfer. The SRC-PEEK gaskets in this study demonstrated higher crystallinity and crystalline orientation and improved monotonic tensile properties compared with bulk PEEK with the ability to effectively insulate Ti6Al4V and CoCrMo alloy surfaces and prevent the initiation of fretting corrosion under high contact-stress conditions. This novel SRC-PEEK material may offer potential as a thin film gasket material for modular tapers. Pending further in vitro and in vivo analyses, this approach may be able to preserve the advantages of modular junctions for surgeons while potentially limiting the downside risks associated with mechanically assisted crevice corrosion.

  1. Carbon monoxide hydrogenation over rhenium-iron oxide catalysts and their characterization by soft X-ray spectroscopy

    SciTech Connect

    Komlyama, M.; Tsunoda, T.; Ogino, Y.

    1986-03-01

    Rhenium-iron oxide catalysts, prepared by the conventional impregnation technique and activated by reduction under various conditions, gave higher selectivities to oxygenates (mainly alcohols) in carbon monoxide hydrogenation than the control iron oxide (magnetite) catalysts. Bulk-sensitive soft X-ray spectroscopy (SXS) along with X-ray diffraction and Mossbauer spectroscopy found that in rhenium-iron oxide catalysts iron oxide is in the form of an intermediate phase represented as (1 - x)Fe/sub 3/O/sub 4/.xFe/sub 8/3/O/sub 4/; between Fe/sub 3/O/sub 4/ and ..gamma..-Fe/sub 2//O/sub 3/. The extent of the formation of this intermediate phase was correlated with the oxygenate selectivities of the rhenium-iron oxide catalysts. The usefulness of SXS in characterizing bulk of solid catalysts was demonstrated.

  2. Analyzing the photonic band gaps in two-dimensional plasma photonic crystals with fractal Sierpinski gasket structure based on the Monte Carlo method

    SciTech Connect

    Zhang, Hai-Feng; Liu, Shao-Bin

    2016-08-15

    In this paper, the properties of photonic band gaps (PBGs) in two types of two-dimensional plasma-dielectric photonic crystals (2D PPCs) under a transverse-magnetic (TM) wave are theoretically investigated by a modified plane wave expansion (PWE) method where Monte Carlo method is introduced. The proposed PWE method can be used to calculate the band structures of 2D PPCs which possess arbitrary-shaped filler and any lattice. The efficiency and convergence of the present method are discussed by a numerical example. The configuration of 2D PPCs is the square lattices with fractal Sierpinski gasket structure whose constituents are homogeneous and isotropic. The type-1 PPCs is filled with the dielectric cylinders in the plasma background, while its complementary structure is called type-2 PPCs, in which plasma cylinders behave as the fillers in the dielectric background. The calculated results reveal that the enough accuracy and good convergence can be obtained, if the number of random sampling points of Monte Carlo method is large enough. The band structures of two types of PPCs with different fractal orders of Sierpinski gasket structure also are theoretically computed for a comparison. It is demonstrate that the PBGs in higher frequency region are more easily produced in the type-1 PPCs rather than in the type-2 PPCs. Sierpinski gasket structure introduced in the 2D PPCs leads to a larger cutoff frequency, enhances and induces more PBGs in high frequency region. The effects of configurational parameters of two types of PPCs on the PBGs are also investigated in detail. The results show that the PBGs of the PPCs can be easily manipulated by tuning those parameters. The present type-1 PPCs are more suitable to design the tunable compacted devices.

  3. Analyzing the photonic band gaps in two-dimensional plasma photonic crystals with fractal Sierpinski gasket structure based on the Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin

    2016-08-01

    In this paper, the properties of photonic band gaps (PBGs) in two types of two-dimensional plasma-dielectric photonic crystals (2D PPCs) under a transverse-magnetic (TM) wave are theoretically investigated by a modified plane wave expansion (PWE) method where Monte Carlo method is introduced. The proposed PWE method can be used to calculate the band structures of 2D PPCs which possess arbitrary-shaped filler and any lattice. The efficiency and convergence of the present method are discussed by a numerical example. The configuration of 2D PPCs is the square lattices with fractal Sierpinski gasket structure whose constituents are homogeneous and isotropic. The type-1 PPCs is filled with the dielectric cylinders in the plasma background, while its complementary structure is called type-2 PPCs, in which plasma cylinders behave as the fillers in the dielectric background. The calculated results reveal that the enough accuracy and good convergence can be obtained, if the number of random sampling points of Monte Carlo method is large enough. The band structures of two types of PPCs with different fractal orders of Sierpinski gasket structure also are theoretically computed for a comparison. It is demonstrate that the PBGs in higher frequency region are more easily produced in the type-1 PPCs rather than in the type-2 PPCs. Sierpinski gasket structure introduced in the 2D PPCs leads to a larger cutoff frequency, enhances and induces more PBGs in high frequency region. The effects of configurational parameters of two types of PPCs on the PBGs are also investigated in detail. The results show that the PBGs of the PPCs can be easily manipulated by tuning those parameters. The present type-1 PPCs are more suitable to design the tunable compacted devices.

  4. Preparation and properties of metallic, superhard rhenium diboride crystals.

    PubMed

    Levine, Jonathan B; Nguyen, Sandy L; Rasool, Haider I; Wright, Jeffrey A; Brown, Stuart E; Kaner, Richard B

    2008-12-17

    Single crystals of ReB(2) have been prepared from an aluminum flux under inert gas flow. The crystals are typically 1-3 mm in diameter and 500 microm thick, growing along the [002] direction with a distinct hexagonal morphology. Vickers microhardness and nanoindentation testing indicate that the (002) plane possesses the highest hardness with measured values of 40.5 and 36.4 GPa, respectively. The elastic anisotropy was examined and the indentation moduli of the basal plane and an (hk0) plane of unknown indices are 675 and 510 GPa, respectively. Four-probe electrical resistivity measurements demonstrate that ReB(2) is the hardest material known to exhibit metallic behavior. Thermogravimetric analysis indicates that the crystals are stable in air up to 1000 degrees C due to the formation of a protective boron oxide coating.

  5. Range Analysis of Thermal Stress and Optimal Design for Tungsten-Rhenium Thin Film Thermocouples Based on Ceramic Substrates

    PubMed Central

    Zhang, Zhongkai; Tian, Bian; Yu, Qiuyue; Shi, Peng; Lin, Qijing; Zhao, Na; Jing, Weixuan; Jiang, Zhuangde

    2017-01-01

    A thermal stress range analysis of tungsten-rhenium thin film thermocouples based on ceramic substrates is presented to analyze the falling off and breakage problems caused by the mismatch of the thermal stresses in thin film thermocouples (TFTCs) and substrate, and nano-indentation experiments are done to measure and calculate the film stress to compare with the simulation results. Optimal design and fabrication of tungsten-rhenium TFTCs based on ceramic substrates is reported. Static high temperature tests are carried out, which show the optimization design can effectively reduce the damage caused by the thermal stress mismatch. PMID:28420088

  6. Biodistribution of rhenium cluster complex K₄[Re6S8(CN)6] in the body of laboratory rats.

    PubMed

    Brylev, K A; Shestopalov, M A; Khripko, O P; Trunova, V A; Zvereva, V V; Wang, C C; Mironov, Yu V; Fedorov, V E

    2013-10-01

    We studied the biodistribution of luminescent octahedral rhenium cluster complex K4[Re6S8(CN)6], a promising agent for photodynamic therapy. It was shown that rhenium complex [Re6S8(CN)6](4-)is mainly accumulated in the liver, the central organ of metabolism, and can be excreted by the kidneys. The cluster complex was also accumulated in the spleen in significant amount, which makes it a promising agent for creation of preparations for diagnostics and treatment of lymphoproliferative disorders. The mean lethal dose of the cluster complex was 0.38 g/kg.

  7. Facile synthesis of single crystalline rhenium (VI) trioxide nanocubes with high catalytic efficiency for photodegradation of methyl orange.

    PubMed

    Chong, Yuan Yi; Fan, Wai Yip

    2013-05-01

    Single-crystalline rhenium trioxide (ReO3) nanocubes have been prepared for the first time without the need of surfactants via controlled reduction of rhenium (VII) oxide (Re2O7), sandwiched between silicon wafers at 250°C. The metallic ReO3 nanocubes are magnetic and possess surface plasmon resonance (SPR) bands down to the NIR region. The nanocubes also show very high catalytic activity toward the photodegradation of methyl orange (MO) under ambient conditions. A mechanism has been proposed to account for the photodegradation process.

  8. The chemistry of rhenium and tungsten porphyrin complexes in low oxidation states. Synthesis and characterization of rhenium and tungsten porphyrin dimers containing metal-metal multiple bonds

    SciTech Connect

    Collmann, J.P.; Garner, J.M.; Woo, L.K. )

    1989-10-11

    The coordination chemistry of rhenium and tungsten porphyrin complexes in low oxidation states is presented. W{sup IV}(Por)(Cl){sub 2}, W{sup II}(Por)(H{sub 5}C{sub 6}C{identical to}CC{sub 6}H{sub 5}) and W{sup II}(OEP)(PEt{sub 3}){sub 2} complexes (Por = 5,10,15,20-tetra(4-tolyl)porphyrin (TTP) or 2,3,7,8,12,13,17,18-octaethylporphyrin (OEP) dianions) were found to be similar to the analogous molybdenum porphyrin complexes by spectroscopic and magnetic measurements. UV-visible and vibrational spectroscopies indicate that these oxidations occur at the metal-metal bond rather than the porphyrin ligand.

  9. From N-alkylimidazole ligands at a rhenium center: ring opening or formation of NHC complexes.

    PubMed

    Huertos, Miguel A; Pérez, Julio; Riera, Lucía; Menéndez-Velázquez, Amador

    2008-10-15

    Cationic rhenium tricarbonyl complexes with three N-alkylimidazole ligands undergo deprotonation of the central CH group upon reaction with 1 equiv of KN(SiMe3)2. For the tris(N-methylimidazole) complex, the metal fragment shifts from N to C, leaving an NHC complex with a nonsubstituted N atom. For compounds with at least one N-mesitylimidazole ligand, the intramolecular attack of the deprotonated carbon onto the central carbon of an N-mesitylimidazole ligand results in ring opening of the latter.

  10. Direct radiometric dating of hydrocarbon deposits using rhenium-osmium isotopes.

    PubMed

    Selby, David; Creaser, Robert A

    2005-05-27

    Rhenium-osmium (Re-Os) data from migrated hydrocarbons establish the timing of petroleum emplacement for the giant oil sand deposits of Alberta, Canada, at 112 +/- 5.3 million years ago. This date does not support models that invoke oil generation and migration for these deposits in the Late Cretaceous. Most Re-Os data from a variety of deposits within the giant hydrocarbon system show similar characteristics, supporting the notion of a single source for these hydrocarbons. The Re-Os data disqualify Cretaceous rocks as the primary hydrocarbon source but suggest an origin from older source rocks. This approach should be applicable to dating oil deposits worldwide.

  11. Exchange interactions and Tc in rhenium-doped silicon: DFT, DFT + U and Monte Carlo calculations.

    PubMed

    Wierzbowska, Małgorzata

    2012-03-28

    Interactions between rhenium impurities in silicon are investigated by means of the density functional theory (DFT) and the DFT + U scheme. All couplings between impurities are ferromagnetic except the Re-Re dimers which in the DFT method are nonmagnetic, due to the formation of the chemical bond supported by substantial relaxation of the geometry. The critical temperature is calculated by means of classical Monte Carlo (MC) simulations with the Heisenberg Hamiltonian. The uniform ferromagnetic phase is obtained with the DFT exchange interactions at room temperature for the impurities concentration of 7%. With the DFT + U exchange interactions, the ferromagnetic clusters form above room temperature in MC samples containing only 3% Re.

  12. Effects of pressure and temperature on the yield strength of tantalum and rhenium

    NASA Astrophysics Data System (ADS)

    Crow, Joseph Allan

    The effects of pressure and temperature on the yield strength of tantalum and the effects of pressure on the yield strength of rhenium were investigated using ruby fluorescence. A new Raman system with a motorized stage and near diffraction limit was built to map 2-dimensionally, the pressures inside of a diamond anvil cell. The 2-dimensional data is used to create contour maps and surface plots of the pressures and calculate the pressure gradients induced in the samples. Using the Birch-Murnaghan equation of state, the final sample thickness, and the pressure gradients, the yield strength as a function of temperature and pressure are calculated.

  13. Superconducting molybdenum-rhenium electrodes for single-molecule transport studies

    SciTech Connect

    Gaudenzi, R.; Island, J. O.; Bruijckere, J. de; Burzurí, E.; Zant, H. S. J. van der; Klapwijk, T. M.

    2015-06-01

    We demonstrate that electronic transport through single molecules or molecular ensembles, commonly based on gold (Au) electrodes, can be extended to superconducting electrodes by combining gold with molybdenum-rhenium (MoRe). This combination induces proximity-effect superconductivity in the gold to temperatures of at least 4.6 K and magnetic fields of 6 T, improving on previously reported aluminum based superconducting nanojunctions. As a proof of concept, we show three-terminal superconductive transport measurements through an individual Fe{sub 4} single-molecule magnet.

  14. Synthesis, molecular structure and magnetic properties of a rhenium(IV) compound with catechol

    NASA Astrophysics Data System (ADS)

    Cuevas, A.; Geis, L.; Pintos, V.; Chiozzone, R.; Sanchíz, J.; Hummert, M.; Schumann, H.; Kremer, C.

    2009-03-01

    A novel Re(IV) complex containing catechol as ligand has been prepared and characterized. The crystal structure of (HNEt 3)(NBu 4)[ReCl 4(cat)]·H 2cat was determined. The rhenium ion presents a distorted octahedral geometry, being bonded to a bidentate catecholate group and four chloride anions. The magnetic properties of the complex were studied, a /2 D/ (the energy gap between ±3/2 and ±1/2 Kramers doublets) value of 190(10) cm -1. This is the largest /2 D/ value reported for Re(IV) up to now.

  15. Migration of epoxidised soybean oil from PVC gaskets of commercial lids: simulation of migration under various conditions and screening of food products from Czech markets.

    PubMed

    Hanušová, Kristýna; Vrbík, Karel; Rajchl, Aleš; Dobiáš, Jaroslav; Sosnovcová, Jitka

    2015-01-01

    Previous studies have shown that a large number of polyvinylchloride (PVC) lid gaskets exceed the existing migration limits for epoxidised soybean oil (ESBO) and correct prediction of ESBO release into food therefore appears to be a difficult issue. ESBO migration from PVC gaskets of metal closures into food simulants and food products from the Czech market is evaluated during a survey in 2009 and subsequently one in 2012 to assess progress in lid manufacturing and official testing conditions. ESBO migration from lids into various food simulants was studied at various temperatures (25, 40 and 60°C) during storage times up to 12 months. ESBO released into food simulants or food products was transmethylated, derivatised and analysed by GC-MS. The levels of ESBO migration in foodstuffs in 2012 exceeded the specific migration limit (SML) in fewer products in comparison with the previous survey. However, most of the products were analysed at a time far from the expiry date and exceedance of the SML at the end of the product shelf life is not therefore excluded. More severe test conditions (60°C for 10 days) for specific migration given by the current European Union legislation (Regulation (EU) No. 10/2011) still seem to be insufficient for the simulation of ESBO migration during long-term storage.

  16. Electrochemical synthesis, structural characterization, and decomposition of rhenium oxoethoxide, Re4O4(OEt)12. Ligand influence on the structure and bonding in the high-valent tetranuclear planar rhenium alkoxide clusters.

    PubMed

    Nikonova, Olesya A; Jansson, Kjell; Kessler, Vadim G; Sundberg, Margareta; Baranov, Alexei I; Shevelkov, Andrei V; Drobot, Dmitrii V; Seisenbaeva, Gulaim A

    2008-02-18

    Anodic oxidation of rhenium in ethanol in the presence of LiCl as a conductive additive results with high yield in formation of a new oxoethoxide cluster, Re(4)O(4)(OEt)(12). The structure of the planar centrosymmetric metal-oxygen core of this molecule is composed of four edge-sharing Re(V)O(6) octahedra. Eight electrons are available for the formation of metal-metal bonds indicated by five relatively short Re-Re distances within the Re 4-rhombus, a "planar butterfly" type cluster. The theoretical calculations are indicating relatively low contribution of metal-metal bonding in the stability of the core. The stability of the +V-oxidation state, unusual for rhenium alkoxides can be at least partially attributed to the size effects in the packing of ligands. The X-ray powder study indicates that treatment of Re(4)O(4)(OEt)(12). in ambient atmosphere rapidly transforms it into a mixed-valence derivative Re(4)O(6)(OEt)(10) with a structure related to the earlier investigated cluster Re(4)O(6)(O(i)Pr)(10). Thermal decomposition of the latter rhenium oxoethoxide results in reduction to rhenium metal at as low temperatures as 380 degrees C, producing aggregates of metal nanoparticles with the average size of 3 nm.

  17. Insertion of polar and nonpolar unsaturated molecules into carbon-rhenium bonds generated by C-H bond activation: synthesis of phthalimidine and indene derivatives.

    PubMed

    Kuninobu, Yoichiro; Tokunaga, Yukimi; Kawata, Atsushi; Takai, Kazuhiko

    2006-01-11

    A rhenium complex, [ReBr(CO)(3)(thf)](2), catalyzes the reaction of an aromatic aldimine with an isocyanate and an acetylene to give a phthalimidine and an indene derivative in a quantitative yield, respectively. The reactions proceed via C-H bond activation, insertion of the isocyanate or the acetylene, intramolecular nucleophilic cyclization to the aldimine of the generated amido- or alkenyl-rhenium species, and reductive elimination. In contrast to ruthenium and rhodium catalysts, which are usually employed in this type of reaction, the rhenium catalyst promotes the insertion of a polar unsaturated molecule. This occurs more easily than the insertion of a nonpolar unsaturated molecule.

  18. Glass coated compressible solid oxide fuel cell seals

    NASA Astrophysics Data System (ADS)

    Rautanen, M.; Thomann, O.; Himanen, O.; Tallgren, J.; Kiviaho, J.

    2014-02-01

    With the growing footprint of solid oxide fuel cell stacks, there is a need to extend the operating range of compressible gaskets towards lower stress levels. This article describes a method to manufacture SOFC seals by coating a compressible sealing material (Thermiculite 866) with glass to obtain good sealing performance even at compression stresses as low as 0.1 MPa. Glass layer can be coated using an organic carrier consisting of terpineol, ethanol and ethyl cellulose. The coated seals can be heat treated by simply ramping the temperature up to operating temperature at 60 Kh-1 and therefore no extra steps, which are typical to glass seals, are required. Coated seals were manufactured using this route and evaluated both ex-situ and in a real stack. Leak rates of 0.1-0.3 ml (m min)-1 were measured at 2-25 mbar overpressure using 50/50 H2/N2. A 30-cell stack was manufactured and tested using coated seals. At nominal operating conditions of 0.25 A cm-2 and 650 °C average cathode temperature, 46% fuel utilization and 20% air utilization the stack had a total hydrogen cross leak of 60 ml min-1 corresponding to 0.7% of the inlet hydrogen flow rate.

  19. COATED ALLOYS

    DOEpatents

    Harman, C.G.; O'Bannon, L.S.

    1958-07-15

    A coating is described for iron group metals and alloys, that is particularly suitable for use with nickel containing alloys. The coating is glassy in nature and consists of a mixture containing an alkali metal oxide, strontium oxide, and silicon oxide. When the glass coated nickel base metal is"fired'' at less than the melting point of the coating, it appears the nlckel diffuses into the vitreous coating, thus providing a closely adherent and protective cladding.

  20. Aluminide coatings

    DOEpatents

    Henager, Jr; Charles, H [Kennewick, WA; Shin, Yongsoon [Richland, WA; Samuels, William D [Richland, WA

    2009-08-18

    Disclosed herein are aluminide coatings. In one embodiment coatings are used as a barrier coating to protect a metal substrate, such as a steel or a superalloy, from various chemical environments, including oxidizing, reducing and/or sulfidizing conditions. In addition, the disclosed coatings can be used, for example, to prevent the substantial diffusion of various elements, such as chromium, at elevated service temperatures. Related methods for preparing protective coatings on metal substrates are also described.

  1. Crystallization of rhenium salts in a simulated low-activity waste borosilicate glass

    SciTech Connect

    Riley, Brian J.; McCloy, John S.; Goel, Ashutosh; Liezers, Martin; Schweiger, Michael J.; Liu, Juan; Rodriguez, Carmen P.; Kim, Dong-Sang

    2013-04-01

    This study presents a new method for looking at the solubility of volatile species in simulated low-activity waste glass. The present study looking at rhenium salts is also applicable to real applications involving radioactive technetium salts. In this synthesis method, oxide glass powder is mixed with the volatiles species, vacuum-sealed in a fused quartz ampoule, and then heat-treated under vacuum in a furnace. This technique restricts the volatile species to the headspace above the melt but still within the sealed ampoule, thus maximizing the volatile concentration in contact with the glass. Various techniques were used to measure the solubility of rhenium in glass and include energy dispersive spectroscopy, wavelength dispersive spectroscopy, laser ablation inductively-coupled plasma mass spectroscopy, and inductively-coupled plasma optical emission spectroscopy. The Re-solubility in this glass was determined to be ~3004 parts per million Re atoms. Above this concentration, the salts separated out of the melt as inclusions and as a low viscosity molten salt phase on top of the melt observed during and after cooling. This salt phase was analyzed with X-ray diffraction, scanning electron microscopy as well as some of the other aforementioned techniques and identified to be composed of alkali perrhenate and alkali sulfate.

  2. Phase composition of heat-resisting alloy modified by ageing and alloyed by rhenium

    NASA Astrophysics Data System (ADS)

    Koneva, Nina; Nikonenko, Elena; Popova, Natalya; Gibert, Ivan; Kozlov, Eduard

    2016-11-01

    The paper presents the transmission electron microscope (TEM) investigations of the structure of Ni-Al-Cr-based superalloy which is obtained by directional crystallization technique. The structural TEM investigations are carried out in two stages: 1) annealing at 1150°C for 1 h and 2) annealing at 1100°C for 480 h. The qualitative and quantitative analysis is given for the structure, phase composition and morphology of heat-resisting alloy additionally alloyed by rhenium Re both in the original state and after thermal treatment. The heat-resisting alloy comprises ˜70 at % Ni, ˜17 at % Al and ˜5 at % Cr. The total amount of the primary alloying elements of Mo, W, Ta, Ti, Co, La was ˜7 at % and 0.4 at % Re. It is shown that the structure of the superalloy is represented by (γ + γ')-phase mixture which has a morphologically correct crystallographic orientation and quasi-monocrystalline structure. σ-phase is formed in this superalloy due to rhenium. Since Re distribution in the alloy is not uniform, only a part of (γ + γ')-phase quasi-cuboids is distorted. It is shown that Re modification distorts the ideal structure of (γ + γ')-phase quasi-cuboids and results in the formation of β-, χ-and σ-phases.

  3. Characterization of rhenium oxide films and their application to liquid crystal cells

    NASA Astrophysics Data System (ADS)

    Cazzanelli, E.; Castriota, M.; Marino, S.; Scaramuzza, N.; Purans, J.; Kuzmin, A.; Kalendarev, R.; Mariotto, G.; Das, G.

    2009-06-01

    Rhenium trioxide exhibits high electronic conductivity, while its open cubic crystal structure allows an appreciable hydrogen intercalation, generating disordered solid phases, with protonic conductivity. Rhenium oxide thin films have been obtained by thermal evaporation of ReO3 powders on different substrates, maintained at different temperatures, and also by reactive magnetron sputtering of a Re metallic target. A comparative investigation has been carried out on these films, by using micro-Raman spectroscopy and x-ray diffraction. Two basic types of solid phases appear to grow in the films: a red metallic HxReO3 compound, with distorted perovskite structures, like in the bulk material, and ordered HReO4 crystals based on tetrahedral perrhenate ions. Because of its conduction properties, the electrical and electro-optical behaviors of ReO3 films deposited on standard indium tin oxide/glass substrate have been tested inside asymmetric nematic liquid crystal cells, showing an appreciable capability of rectification of their electro-optical response, in similar way to tungsten trioxide.

  4. Computer acquired performance data from a chemically vapor-deposited-rhenium, niobium planar diode

    NASA Technical Reports Server (NTRS)

    Manista, E. J.; Morris, J. F.; Smith, A. L.; Lancashire, R. B.

    1973-01-01

    Performance data from a chemically vapor-deposited-rhenium, niobium thermionic converter are presented. The planar converter has a guard-ringed collector and a nominal fixed spacing of 0.25 mm (10 mils). The data were obtained by using a computerized acquisition system and are available on request to one of the authors on microfiche as individual and composite parametric current, voltage curves. The parameters are the temperatures of the emitter T sub E collector T sub C, and cesium reservoir T sub R. The composite plots have constant T sub E and varying T sub C or T sub R, or both. Current, voltage envelopes having constant T sub E with and without fixed T sub C appear in the present report. The diode was tested at increments between 1600 and 2000 K for the emitter Hohlraum, 800 to 1100 K for the collector, and 540 and 650 K for the reservoir. A total of 312 current, voltage curves were obtained in the present performance evaluation. Current, voltage envelopes from three rhenium emitter converters evaluated in the present program are also given. The data are compared at commom emitter Hohlraum temperatures.

  5. Antitumor activity of a rhenium (I)-diselenoether complex in experimental models of human breast cancer.

    PubMed

    Collery, Philippe; Mohsen, Ahmed; Kermagoret, Anthony; Corre, Samantha; Bastian, Gérard; Tomas, Alain; Wei, Ming; Santoni, François; Guerra, Nadia; Desmaële, Didier; d'Angelo, Jean

    2015-08-01

    Rhenium (I)-diselenother (Re-diselenoether) is a water soluble metal-based compound, combining one atom of rhenium and two atoms of selenium. This compound has been reported to exhibit marked activities against several solid tumor cell lines. We now disclose an improved synthesis of this complex. The Re-diselenoether showed a potent inhibitory effect on MDA-MB231 cell division in vitro, which lasted when the complex was no longer present in the culture. Re-diselenoether induced a remarkable reduction of the volume of the primitive breast tumors and of the pulmonary metastases without clinical signs of toxicity, in mice-bearing a MDA-MB231 Luc+ tumor, orthotopically transplanted, after a daily oral administration at the dose of 10 mg/kg/d. Interestingly, an antagonism was observed when cisplatin was administered as a single i.p. injection 1 week after the end of the Re-diselenoether administration. In an effort to gain insight of the mechanisms of action of Re-diselenoether complex, interaction with 9-methylguanine as a nucleic acid base model was studied. We have shown that Re-diselenoether gave both mono- and bis-guanine Re adducts, the species assumed to be responsible for the DNA intrastrand lesions.

  6. Characterization of rhenium oxide films and their application to liquid crystal cells

    SciTech Connect

    Cazzanelli, E.; Castriota, M.; Marino, S.; Scaramuzza, N.; Purans, J.; Kuzmin, A.; Kalendarev, R.; Mariotto, G.; Das, G.

    2009-06-01

    Rhenium trioxide exhibits high electronic conductivity, while its open cubic crystal structure allows an appreciable hydrogen intercalation, generating disordered solid phases, with protonic conductivity. Rhenium oxide thin films have been obtained by thermal evaporation of ReO{sub 3} powders on different substrates, maintained at different temperatures, and also by reactive magnetron sputtering of a Re metallic target. A comparative investigation has been carried out on these films, by using micro-Raman spectroscopy and x-ray diffraction. Two basic types of solid phases appear to grow in the films: a red metallic H{sub x}ReO{sub 3} compound, with distorted perovskite structures, like in the bulk material, and ordered HReO{sub 4} crystals based on tetrahedral perrhenate ions. Because of its conduction properties, the electrical and electro-optical behaviors of ReO{sub 3} films deposited on standard indium tin oxide/glass substrate have been tested inside asymmetric nematic liquid crystal cells, showing an appreciable capability of rectification of their electro-optical response, in similar way to tungsten trioxide.

  7. [Antioxidant properties of cluster rhenium compounds and their effect on erythropoiesis of rats with guerin carcinoma].

    PubMed

    Voronkova, Y S; Babiy, S O; Ivans'kar, L V; Shtemenko, O V; Shtemenko, N I

    2015-01-01

    Biochemical characteristics of kidneys, pe- ripheral blood and bone marrow of rats in model of tumor growth under introduction of cisplatin and cis-tetrachlorodi-μ-isobutyratodirhenium(III), cis-Re2(i-C3H7COO)2Cl4 (I) have been investigated. It was shown that introduction of I alone and together with cisplatin led to decrease of biochemical markers of oxidation of lipids and proteins in tissue homogenates of the kidneys, change of enzyme activity in the urea and tissue homogenates of the kidneys, by a decrease of filtration function of kidneys. Introduction of nanoliposomal forms of the rhenium cluster compound led to a practically normal morphological picture of bone marrow and increase of the RBC (by 60%) with normalization of hematocrit counts, and decrease of quantities of destructed RBC (3.2 times) in comparison with the tumor-bearing animals. A tentative scheme of influence of cluster rhenium compound on erythropoiesis through regulation of synthesis of erythropoietin in kidneys has been proposed.

  8. Tungsten alloyed with rhenium as an advanced material for heat-resistant silicon ICs interconnects

    NASA Astrophysics Data System (ADS)

    Belov, A. N.; Chaplygin, Yu. A.; Golishnikov, A. A.; Kostyukov, D. A.; Putrya, M. G.; Safonov, S. O.; Shevyakov, V. I.

    2016-12-01

    This paper presents the results of comparative analysis of the electrical and mechanical characteristics of the tungsten and tungsten alloyed with rhenium films deposited on silicon, from the point of view of their use as interconnects in silicon ICs. W and W (Re-5%) alloyed with rhenium films were made by magnetron deposition. Sheet resistivity for W and W (Re- 5%) was 13 and 27 μOhm·cm respectively. Elemental composition the formed films was examined by Auger spectroscopy. To investigate the electromigration resistance of the conductors a methodology based on the accelerated electromigration testing at constant temperature was used. A comparative analysis of the mechanical stresses carried out in the W and W(Re - 5%) films. For this purpose was applied non-destructive method for optical laser scanning. At the same time, these films explored their ability of adhesion to silicon and silicon oxide. It is shown that the pull force of the W(Re - 5%) films was 1500 G/mm2, of the W films 700 G/mm2

  9. Synthesis, characterisation and bioimaging of a fluorescent rhenium-containing PNA bioconjugate.

    PubMed

    Gasser, Gilles; Pinto, Antonio; Neumann, Sebastian; Sosniak, Anna M; Seitz, Michael; Merz, Klaus; Heumann, Rolf; Metzler-Nolte, Nils

    2012-02-28

    A new rhenium tricarbonyl complex of a bis(quinoline)-derived ligand (2-azido-N,N-bis((quinolin-2-yl)methyl)ethanamine, L-N(3)), namely [Re(CO)(3)(L-N(3))]Br was synthesized and characterized in-depth, including by X-ray crystallography. [Re(CO)(3)(L-N(3))]Br exhibits a strong UV absorbance in the range 300-400 nm with a maximum at 322 nm, and upon photoexcitation, shows two distinct emission bands at about 430 and 560 nm in various solvents (water, ethylene glycol). [Re(CO)(3)(L-N(3))]Br could be conjugated, on a solid phase, to a peptide nucleic acid (PNA) oligomer using the copper(I)-catalyzed azide-alkyne cycloaddition reaction (Cu-AAC, "click" chemistry) and an alkyne-containing PNA building block to give Re-PNA. It was demonstrated that upon hybridisation with a complementary DNA strand (DNA), the position of the maxima and emission intensity for the hybrid Re-PNA·DNA remained mainly unchanged compared to those of the single strand Re-PNA. The rhenium-containing PNA oligomer Re-PNA could be then mediated in living cells where they have been shown to be non-toxic contrary to the general notion that organometallic compounds are usually unstable under physiological conditions and/or cytotoxic. Furthermore, Re-PNA could be detected in living cells using fluorescent microscopy.

  10. Photocatalytic H2 production from water with rhenium and cobalt complexes.

    PubMed

    Probst, Benjamin; Guttentag, Miguel; Rodenberg, Alexander; Hamm, Peter; Alberto, Roger

    2011-04-18

    Photocatalytic hydrogen production in pure water for three component systems using a series of rhenium-based photosensitizers (PS) and cobalt-based water reduction catalysts (WRC), with triethanolamine (TEOA) as an irreversible electron donor, is described. Besides the feasibility of this reaction in water, key findings are reductive quenching of the excited state of the PS by TEOA (k(q) = 5-8 × 10(7) M(-1) s(-1); Φ(cage) = 0.75) and subsequent transfer of an electron to the WRC (k(Co(III)) = 1.1 × 10(9) M(-1) s(-1)). Turnover numbers in rhenium (TON(Re), H/Re) above 500 were obtained, whereas TON(Co) (H(2)/Co) did not exceed 17. It is shown that the cobalt-based WRC limits long-term performance. Long-term performance critically depends on pH and the type of WRC used but is unaffected by the type of PS or the concentration of WRC. A quantum yield of 30% was obtained (H/photon).

  11. Rhenium volatilisation as caesium perrhenate from simulated vitrified high level waste from a melter crucible

    SciTech Connect

    Taylor, T.A.; Short, R.J.; Gribble, N.R.; Roe, J.I.; Steele, C.J.

    2013-07-01

    The Waste Vitrification Plant (WVP) converts Highly Active Liquor (HAL) from spent nuclear fuel reprocessing into a stable vitrified product. Recently WVP have been experiencing accumulation of solids in their primary off gas (POG) system leading to potential blockages. Chemical analysis of the blockage material via Laser Induced Breakdown Spectroscopy (LIBS) has shown it to exclusively consist of caesium, technetium and oxygen. The solids are understood to be caesium pertechnetate (CsTcO{sub 4}), resulting from the volatilisation of caesium and technetium from the high level waste glass melt. Using rhenium as a chemical surrogate for technetium, a series of full scale experiments have been performed in order to understand the mechanism of rhenium volatilisation as caesium perrhenate (CsReO{sub 4}), and therefore technetium volatilisation as CsTcO{sub 4}. These experiments explored the factors governing volatilisation rates from the melt, potential methods of minimising the amount of volatilisation, and various strategies for mitigating the deleterious effects of the volatile material on the POG. This paper presents the results from those experiments, and discusses potential methods to minimise blockages that can be implemented on WVP, so that the frequency of the CsTcO{sub 4} blockages can be reduced or even eradicated altogether. (authors)

  12. A hexadentate bis(thiosemicarbazonato) ligand: rhenium(V), iron(III) and cobalt(III) complexes.

    PubMed

    Paterson, Brett M; White, Jonathan M; Donnelly, Paul S

    2010-03-21

    A new 1,3-diaminopropane bridged bis(thiosemicarbazone) ligand (H(4)L) has been synthesised. The new hexadentate ligand is capable of forming six coordinate complexes with rhenium(V), iron(III) and cobalt(III). In the case of the iron(III) and cobalt(III) complexes the ligand doubly deprotonates to give the monocations [Fe(III)(H(2)L)](+) and [Co(III)(H(2)L)](+) in which the metal ion is in a distorted octahedral environment. In the rhenium(V) complex the ligand loses four protons by deprotonation of both secondary amine nitrogen atoms to give [Re(V)(L)](+) with the metal ion in a distorted trigonal prismatic coordination environment. [Re(V)(L)](+) represents a rare example of a rhenium(V) complex that does not contain one of the ReO(3+), ReN(2+) or Re(NPh)(2+) cores. The new ligand and metal complexes have been characterised by a combination of NMR spectroscopy, X-ray crystallography, mass spectrometry and microanalysis. The electrochemistry of [Fe(III)(H(2)L)](+), [Co(III)(H(2)L)](+) and [Re(V)(L)](+) has been investigated by cyclic voltammetry with each complex undergoing a single electron reduction event. It is possible to prepare the rhenium(V) complex from ReOCl(3)(PPh(3))(2) or directly from [ReO(4)](-) with the addition of a reductant, which suggests the new ligand may be of interest in the development of rhenium radiopharmaceuticals.

  13. Intracellular distribution and stability of a luminescent rhenium(i) tricarbonyl tetrazolato complex using epifluorescence microscopy in conjunction with X-ray fluorescence imaging.

    PubMed

    Wedding, J L; Harris, H H; Bader, C A; Plush, S E; Mak, R; Massi, M; Brooks, D A; Lai, B; Vogt, S; Werrett, M V; Simpson, P V; Skelton, B W; Stagni, S

    2017-04-19

    Optical epifluorescence microscopy was used in conjunction with X-ray fluorescence imaging to monitor the stability and intracellular distribution of the luminescent rhenium(i) complex fac-[Re(CO)3(phen)L], where phen = 1,10-phenathroline and L = 5-(4-iodophenyl)tetrazolato, in 22Rv1 cells. The rhenium complex showed no signs of ancillary ligand dissociation, a conclusion based on data obtained via X-ray fluorescence imaging aligning iodine and rhenium distributions. A diffuse reticular localisation was detected for the complex in the nuclear/perinuclear region of cells, by either optical or X-ray fluorescence imaging techniques. X-ray fluorescence also showed that the rhenium complex disrupted the homeostasis of some biologically relevant elements, such as chlorine, potassium and zinc.

  14. Effect of Iron and Carbonation of the Diffusion of Iodine and Rhenium in Waste Encasement Concrete and Soil Fill Material under Hydraulically Unsaturated Conditions

    SciTech Connect

    Wellman, Dawn M.; Parker, Kent E.; Powers, Laura; Whyatt, Greg A.; Clayton, Libby N.; Mattigod, Shas V.; Wood, Marcus I.

    2008-07-31

    Assessing long-term performance of Category 3 cement wasteforms and accurate prediction for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e. sorption or precipitation). A set of sediment-concrete half-cell diffusion experiments was conducted under unsaturated conditions (4% and 7% by weight moisture content) using carbonated and non-carbonated concrete-soil half-cells. Results indicate the behavior of rhenium and iodine release was comparable within a given half-cell test. Diffusivity in soil is a function of moisture content; a 3% increase in moisture content affords a one to two order of magnitude increase in diffusivity. Release of iodine and rhenium was 1 to 3 orders of magnitude less from non-carbonated, relative to carbonated, concrete monoliths. Inclusion of iron in non-carbonate monoliths resulted in the lowest concrete diffusivity values for both iodine and rhenium. This suggests that in the presence of iron, iodine and rhenium are converted to reduced species, which are less soluble and better retained within the concrete monolith. The release of iodine and rhenium was greatest from iron-bearing, carbonated concrete monoliths, suggesting carbonation negates the effect of iron on the retention of iodine and rhenium within concrete monoliths. This is likely due to enhanced formation of microcracks in the presence of iron, which provide preferential paths for contaminant migration. Although the release of iodine and rhenium were greatest from carbonated concrete monoliths containing iron, the migration of iodine and rhenium within a given half-cell is dependent on the moisture content, soil diffusivity, and diffusing species.

  15. Quantitative experimental determination of the solid solution hardening potential of rhenium, tungsten and molybdenum in single-crystal nickel-based superalloys

    SciTech Connect

    Fleischmann, Ernst; Miller, Michael K.; Affeldt, Ernst; Glatzel, Uwe

    2015-01-31

    Here, the solid-solution hardening potential of the refractory elements rhenium, tungsten and molybdenum in the matrix of single-crystal nickel-based superalloys was experimentally quantified. Single-phase alloys with the composition of the nickel solid-solution matrix of superalloys were cast as single crystals, and tested in creep at 980 °C and 30–75 MPa. The use of single-phase single-crystalline material ensures very clean data because no grain boundary or particle strengthening effects interfere with the solid-solution hardening. This makes it possible to quantify the amount of rhenium, tungsten and molybdenum necessary to reduce the creep rate by a factor of 10. Rhenium is more than two times more effective for matrix strengthening than either tungsten or molybdenum. The existence of rhenium clusters as a possible reason for the strong strengthening effect is excluded as a result of atom probe tomography measurements. If the partitioning coefficient of rhenium, tungsten and molybdenum between the γ matrix and the γ' precipitates is taken into account, the effectiveness of the alloying elements in two-phase superalloys can be calculated and the rhenium effect can be explained.

  16. Quantitative experimental determination of the solid solution hardening potential of rhenium, tungsten and molybdenum in single-crystal nickel-based superalloys

    DOE PAGES

    Fleischmann, Ernst; Miller, Michael K.; Affeldt, Ernst; ...

    2015-01-31

    Here, the solid-solution hardening potential of the refractory elements rhenium, tungsten and molybdenum in the matrix of single-crystal nickel-based superalloys was experimentally quantified. Single-phase alloys with the composition of the nickel solid-solution matrix of superalloys were cast as single crystals, and tested in creep at 980 °C and 30–75 MPa. The use of single-phase single-crystalline material ensures very clean data because no grain boundary or particle strengthening effects interfere with the solid-solution hardening. This makes it possible to quantify the amount of rhenium, tungsten and molybdenum necessary to reduce the creep rate by a factor of 10. Rhenium is moremore » than two times more effective for matrix strengthening than either tungsten or molybdenum. The existence of rhenium clusters as a possible reason for the strong strengthening effect is excluded as a result of atom probe tomography measurements. If the partitioning coefficient of rhenium, tungsten and molybdenum between the γ matrix and the γ' precipitates is taken into account, the effectiveness of the alloying elements in two-phase superalloys can be calculated and the rhenium effect can be explained.« less

  17. Metal Coatings

    NASA Technical Reports Server (NTRS)

    1994-01-01

    During the Apollo Program, General Magnaplate Corporation developed process techniques for bonding dry lubricant coatings to space metals. The coatings were not susceptible to outgassing and offered enhanced surface hardness and superior resistance to corrosion and wear. This development was necessary because conventional lubrication processes were inadequate for lightweight materials used in Apollo components. General Magnaplate built on the original technology and became a leader in development of high performance metallurgical surface enhancement coatings - "synergistic" coatings, - which are used in applications from pizza making to laser manufacture. Each of the coatings is designed to protect a specific metal or group of metals to solve problems encountered under operating conditions.

  18. Click-to-Chelate: development of technetium and rhenium-tricarbonyl labeled radiopharmaceuticals.

    PubMed

    Kluba, Christiane A; Mindt, Thomas L

    2013-03-12

    The Click-to-Chelate approach is a highly efficient strategy for the radiolabeling of molecules of medicinal interest with technetium and rhenium-tricarbonyl cores. Reaction of azide-functionalized molecules with alkyne prochelators by the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC; click reaction) enables the simultaneous synthesis and conjugation of tridentate chelating systems for the stable complexation of the radiometals. In many cases, the functionalization of (bio)molecules with the ligand system and radiolabeling can be achieved by convenient one-pot procedures. Since its first report in 2006, Click-to-Chelate has been applied to the development of numerous novel radiotracers with promising potential for translation into the clinic. This review summarizes the use of the Click-to-Chelate approach in radiopharmaceutical sciences and provides a perspective for future applications.

  19. Incorporation and distribution of rhenium in a borosilicate glass melt heat treated in a sealed ampoule

    SciTech Connect

    Kim, Dong-Sang; Schweiger, Michael J.

    2013-07-25

    We investigated a mass balance of rhenium (used as a surrogate for technetium-99) in a borosilicate glass that was mixed with excess Re source (KReO4) beyond its solubility and heat treated in a vacuum-sealed fused silica ampoule. Distribution of Re in the bulk of the glass, in a salt phase formed on the melt surface, and in condensate material deposited on the ampoule wall was evaluated to understand the Re migration into different phases during the reaction between the molten glass and KReO4. The information gained from this study will contribute to an effort to understand the mechanism of technetium retention in or escape from glass melt during early stages of glass batch melting, which is a goal of the present series of studies.

  20. Diffusion of Iodine and Rhenium in Category 3 Waste Encasement Concrete and Soil Fill Material

    SciTech Connect

    Wellman, Dawn M.; Mattigod, Shas V.; Whyatt, Greg A.; Powers, Laura; Parker, Kent E.; Wood, Marcus I.

    2006-12-15

    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e. sorption or precipitation). This understanding will enable accurate prediction of radionuclide fate when the waste forms come in contact with groundwater. A set of diffusion experiments using carbonated and non-carbonated concrete-soil half cells was conducted under unsaturated conditions (4% and 7% by wt moisture content). Spiked concrete half-cell specimens were prepared with and without colloidal metallic iron addition and were carbonated using supercritical carbon dioxide. Spikes of I and Re were added to achieve measurable diffusion profile in the soil part of the half-cell. In addition, properties of concrete materials likely to influence radionuclide migration such as carbonation were evaluated in an effort to correlate these properties with the release of iodine and rhenium.

  1. Pressure induced enhancement of the magnetic ordering temperature in rhenium(IV) monomers

    NASA Astrophysics Data System (ADS)

    Woodall, Christopher H.; Craig, Gavin A.; Prescimone, Alessandro; Misek, Martin; Cano, Joan; Faus, Juan; Probert, Michael R.; Parsons, Simon; Moggach, Stephen; Martínez-Lillo, José; Murrie, Mark; Kamenev, Konstantin V.; Brechin, Euan K.

    2016-12-01

    Materials that demonstrate long-range magnetic order are synonymous with information storage and the electronics industry, with the phenomenon commonly associated with metals, metal alloys or metal oxides and sulfides. A lesser known family of magnetically ordered complexes are the monometallic compounds of highly anisotropic d-block transition metals; the `transformation' from isolated zero-dimensional molecule to ordered, spin-canted, three-dimensional lattice being the result of through-space interactions arising from the combination of large magnetic anisotropy and spin-delocalization from metal to ligand which induces important intermolecular contacts. Here we report the effect of pressure on two such mononuclear rhenium(IV) compounds that exhibit long-range magnetic order under ambient conditions via a spin canting mechanism, with Tc controlled by the strength of the intermolecular interactions. As these are determined by intermolecular distance, `squeezing' the molecules closer together generates remarkable enhancements in ordering temperatures, with a linear dependence of Tc with pressure.

  2. Theoretical study of the rhenium-alkane interaction in transition metal-alkane sigma-complexes.

    PubMed

    Cobar, Erika A; Khaliullin, Rustam Z; Bergman, Robert G; Head-Gordon, Martin

    2007-04-24

    Metal-alkane binding energies have been calculated for [CpRe(CO)2](alkane) and [(CO)2M(C5H4)C[triple bond]C(C5H4)M(CO)2](alkane), where M = Re or Mn. Calculated binding energies were found to increase with the number of metal-alkane interaction sites. In all cases examined, the manganese-alkane binding energies were predicted to be significantly lower than those for the analogous rhenium-alkane complexes. The metal (Mn or Re)-alkane interaction was predicted to be primarily one of charge transfer, both from the alkane to the metal complex (70-80% of total charge transfer) and from the metal complex to the alkane (20-30% of the total charge transfer).

  3. Molybdenum-rhenium alloy based high-Q superconducting microwave resonators

    SciTech Connect

    Singh, Vibhor Schneider, Ben H.; Bosman, Sal J.; Merkx, Evert P. J.; Steele, Gary A.

    2014-12-01

    Superconducting microwave resonators (SMRs) with high quality factors have become an important technology in a wide range of applications. Molybdenum-Rhenium (MoRe) is a disordered superconducting alloy with a noble surface chemistry and a relatively high transition temperature. These properties make it attractive for SMR applications, but characterization of MoRe SMR has not yet been reported. Here, we present the fabrication and characterization of SMR fabricated with a MoRe 60–40 alloy. At low drive powers, we observe internal quality-factors as high as 700 000. Temperature and power dependence of the internal quality-factors suggest the presence of the two level systems from the dielectric substrate dominating the internal loss at low temperatures. We further test the compatibility of these resonators with high temperature processes, such as for carbon nanotube chemical vapor deposition growth, and their performance in the magnetic field, an important characterization for hybrid systems.

  4. Hydrodeoxygenation of vicinal OH groups over heterogeneous rhenium catalyst promoted by palladium and ceria support.

    PubMed

    Ota, Nobuhiko; Tamura, Masazumi; Nakagawa, Yoshinao; Okumura, Kazu; Tomishige, Keiichi

    2015-02-02

    Heterogeneous ReOx-Pd/CeO2 catalyst showed excellent performance for simultaneous hydrodeoxygenation of vicinal OH groups. High yield (>99%), turnover frequency (300 h(-1)), and turnover number (10,000) are achieved in the reaction of 1,4-anhydroerythritol to tetrahydrofuran. This catalyst can be applied to sugar alcohols, and mono-alcohols and diols are obtained in high yields (≥85%) from substrates with even and odd numbers of OH groups, respectively. The high catalytic performance of ReOx-Pd/CeO2 can be assigned to rhenium species with +4 or +5 valence state, and the formation of this species is promoted by H2/Pd and the ceria support. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Computer acquired performance data from an etched-rhenium, molybdenum planar diode

    NASA Technical Reports Server (NTRS)

    Manista, E. J.

    1972-01-01

    Performance data from an etched-rhenium, molybdenum thermionic converter are presented. The planar converter has a guard-ringed collector and a fixed spacing of 0.254 mm (10 mils). The data were acquired by using a computer and are available on microfiche as individual or composite parametric current, voltage curves. The parameters are the temperatures of the emitter T sub E, collector T sub C and cesium reservoir T sub R. The composite plots have constant T sub E, and varying T sub C or T sub R, or both. The envelope and composite plots having constant I sub E are presented. The diode was tested at increments between 1500 and 2000 K for the emitter, 750 and 1100 K for the collector, and 540 and 640 K for the reservoir. In all, 774 individual current, voltage curves were obtained.

  6. Hot rocket plume experiment - Survey and conceptual design. [of rhenium-iridium bipropellants

    NASA Technical Reports Server (NTRS)

    Millard, Jerry M.; Luan, Taylor W.; Dowdy, Mack W.

    1992-01-01

    Attention is given to a space-borne engine plume experiment study to fly an experiment which will both verify and quantify the reduced contamination from advanced rhenium-iridium earth-storable bipropellant rockets (hot rockets) and provide a correlation between high-fidelity, in-space measurements and theoretical plume and surface contamination models. The experiment conceptual design is based on survey results from plume and contamination technologists throughout the U.S. With respect to shuttle use, cursory investigations validate Hitchhiker availability and adaptability, adequate remote manipulator system (RMS) articulation and dynamic capability, acceptable RMS attachment capability, adequate power and telemetry capability, and adequate flight altitude and attitude/orbital capability.

  7. Synthesis and characterization of Lanthanide Aluminotungstates and Rhenium Polyoxometalates: Potential Application in Molecular Information Storage Devices

    NASA Astrophysics Data System (ADS)

    Bian, Fang

    2011-12-01

    Polyoxometalates (abbreviated as POMs) are metal-oxide clusters with frameworks built from group 5 or 6 transition metals linked by shared oxide ions. The Keggin structure is one of the most famous structural forms of POMs. Keggin anions have a general formula of [XM12O40 ]n-, where X is a p-block atom and M is a transition metal atom such as W or Mo. Upon removal of one MO4+ unit from the Keggin anion, the monovacant structure [XM11O39] n- is formed. Those POMs that have lost one or more metal center are called lacunary POMs, which are very nice building blocks for the fabrication of coordination polymers. My research focuses on two facets of POM chemistry: 1) Lanthanide chemistry of aluminum tungstate monovacant Keggin and 2) Rhenium chemistry of aluminum tungstate Keggin and Wells-Dawson POM alpha1 -P2W17O61. In lanthanide POM research area, we obtained the following results: 1) The starting material aluminum tungstate monovacant Keggin α-K 9AlW12O39 was synthesized. Its single crystal was firstly identified by multinuclear NMR and X-ray crystallography. Its redox properties on the nano-scale solid state were determined by Conducting Electrostatic Force Mode (EFM) probes. It is well known that for POMs, a number of varies redox states are normally stable and reversible. Thus we estimated that POMs can potentially be used in molecular information storage applications, which we refer to as "redox disk drives". 2) Eight lanthanide aluminum tungstate Keggin complexes were synthesized. In their molecular structures (identified by multinuclear NMR and X-ray crystallography), each α-AlW11O39 is connected by lanthanide (III) cations to form 1D and 2D networks. All AlW11O39 Keggin POMs are regularly aligning on a flat plane. Microscopic data also verified that there is layer-by-layer morphology in this series of compounds. Overall, we postulate that aluminum tungstate Keggin POMs are a very promising materials for making future information storage device because they

  8. Osmium isotopes in Ivory Coast tektites: Confirmation of a meteoritic component and rhenium depletion

    NASA Astrophysics Data System (ADS)

    Koeberl, Christian; Shirey, Steven B.

    1993-03-01

    The sensitive negative thermal ionization mass spectrometry method was used for the measurement of concentrations and isotopic ratios of osmium and rhenium in four Ivory Coast tektites. These tektites have crustal major and trace element composition, as well as large negative epsilonNd(-20) and positive epsilonSr(+260 to +300) which are characteristic for old continental crust. Os concentrations ranging from 0.09 to 0.30 ppb were found, clearly much higher than average crustal values, Os-187/Os-186 ratios of about 1.2-1.7, and low Re-187/Os-186 ratios. These results show unambiguously the existence of a meteoritic component (on the order of 0.06%) in the Ivory Coast tektites. Low Re abundances are the result of fractionation of Re during the impact.

  9. Osmium isotopes in Ivory Coast tektites: Confirmation of a meteoritic component and rhenium depletion

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian; Shirey, Steven B.

    1993-01-01

    The sensitive negative thermal ionization mass spectrometry method was used for the measurement of concentrations and isotopic ratios of osmium and rhenium in four Ivory Coast tektites. These tektites have crustal major and trace element composition, as well as large negative epsilon(sub Nd)(-20) and positive epsilon(sub Sr)(+260 to +300) which are characteristic for old continental crust. Os concentrations ranging from 0.09 to 0.30 ppb were found, clearly much higher than average crustal values, Os-187/Os-186 ratios of about 1.2-1.7, and low Re-187/Os-186 ratios. These results show unambiguously the existence of a meteoritic component (on the order of 0.06%) in the Ivory Coast tektites. Low Re abundances are the result of fractionation of Re during the impact.

  10. Formation, characterization and computational studies of mono- and dinuclear rhenium(I) chromone compounds

    NASA Astrophysics Data System (ADS)

    Ebinumoliseh, Ifeoma; Booysen, Irvin Noel; Akerman, Matthew Piers; Xulu, Bheki

    2016-11-01

    Herein, we report the formation and characterization of a novel dinuclear rhenium(I) compound, fac-(Re(CO)3Br)2(μ-chret) (1) [chret = N, N'-bis(2-amino-3-imino)methylenechromone-1,2-ethane] and a mononuclear metal complex, fac-[Re(CO)3(bzch)Br] (2) [bzch = 2-benzimidazole-4H-chromen-4-one]. The metal complexes were characterized by 1H NMR-, IR-, UV-Vis, melting point and conductivity measurements. The solid-state structures for 1 and 2 were confirmed via single crystal X-ray analysis. X-ray studies of 2 revealed the transformation of the chb diimine into the bzch chelator (in 2). The simulated IR spectra for the respective metal complexes provided insight in the interpretation of their corresponding experimental spectra.

  11. Hot rocket plume experiment - Survey and conceptual design. [of rhenium-iridium bipropellants

    NASA Technical Reports Server (NTRS)

    Millard, Jerry M.; Luan, Taylor W.; Dowdy, Mack W.

    1992-01-01

    Attention is given to a space-borne engine plume experiment study to fly an experiment which will both verify and quantify the reduced contamination from advanced rhenium-iridium earth-storable bipropellant rockets (hot rockets) and provide a correlation between high-fidelity, in-space measurements and theoretical plume and surface contamination models. The experiment conceptual design is based on survey results from plume and contamination technologists throughout the U.S. With respect to shuttle use, cursory investigations validate Hitchhiker availability and adaptability, adequate remote manipulator system (RMS) articulation and dynamic capability, acceptable RMS attachment capability, adequate power and telemetry capability, and adequate flight altitude and attitude/orbital capability.

  12. Effect of rhenium doping on various physical properties of single crystals of MoSe2

    NASA Astrophysics Data System (ADS)

    Vora, Mihir M.; Vora, Aditya M.

    2012-01-01

    Effect of rhenium doping is examined in single crystals of MoSe2 viz. MoRe0.005Se1.995, MoRe0.001Se1.999 and Mo0.995Re0.005Se2, which is grown by using the direct vapor transport (DVT) technique. The grown crystals are structurally characterized by X-ray diffraction, by determining their lattice parameters a and c, and X-ray density. Also, the Hall effect and thermoelectric power (TEP) measurements show that the single crystals exhibit a p-type semiconducting nature. The direct and indirect band gap measurements are also undertaken on these semiconducting materials.

  13. Rhenium-osmium concentration and isotope systematics in group IIAB iron meteorites

    USGS Publications Warehouse

    Morgan, J.W.; Horan, M.F.; Walker, R.J.; Grossman, J.N.

    1995-01-01

    Rhenium and osmium abundances, and osmium isotopic compositions were measured by negative thermal ionization mass spectrometry in thirty samples, including replicates, of five IIA and eight IIB iron meteorites. Log plots of Os vs. Re abundances for IIA and IIB irons describe straight lines that approximately converge on Lombard, which has the lowest Re and Os abundances and highest 187Re/188Os measured in a IIA iron to date. The linear IIA trend may be exactly reproduced by fractional crystallization, but is not well fitted using variable partition coefficients. The IIB iron trend, however, cannot be entirely explained by simple fractional crystallization. One explanation is that small amounts of Re and Os were added to the asteroid core during the final stages of crystallization. Another possibility is that diffusional enrichment of Os may have occurred in samples most depleted in Re and Os. -from Authors

  14. Radiolabeling antibodies and other proteins with technetium or rhenium by regulated reduction

    SciTech Connect

    Rhodes, B.A.

    1992-01-07

    This patent describes a method of radiolabeling a protein containing disulfide bonds with a radionuclide selected from the group consisting of technetium and rhenium to obtain stable labeling. It comprises incubating the protein containing disulfide bonds with a first reducing agent, the period of incubation being sufficient to reduce available disulfide bonds to sulfhydryl groups while preventing excessive fragmentation of the protein; purifying the reduced protein to substantially remove the first reducing agent and impurities; adding a source of stannous ion agent to the reduced protein in a sufficient amount to reduce the radionuclide, the radionuclide to be added in a subsequent step; radiolabeling the purified reduced protein by adding the radionuclide, whereby the stannous ion agent reduces the radionuclide and the reduced radionuclide and reduced protein forms radionuclide-containing and sulfur-containing complexes.

  15. [Toxicity and antitumoral activity of two new complex compounds of rhenium].

    PubMed

    Natorkhin, M I; Stukov, A N; Filov, V A

    2002-01-01

    Toxicity and antitumor action of two new complex compounds of rhenium (K2 [ReCl6] and [ReCl(4).2C6H4N2]) were investigated. LD50 of K2 [ReCl6], i.v., was 136 +/- 37 mg/kg; i.p.,--272 +/- 74 mg/kg. LD50 of [ReCl(4).2C6H4N2], i.v., was 543 +/- 148 mg/kg; i.p., 600 mg/kg was tolerable. Single maximum tolerable dose of 200 mg/kg K2 [ReCl6], i.p., did not influence the growth of ascitic tumor of Ehrlich, nor did daily intravenous dose of 50 mg/kg inhibit solid tumor of Ehrlich. No inhibition by [ReCl(4).2C6H4N2] was registered when 25 or 50 mg/kg were administered.

  16. Synthesis, structure and magnetic properties of trans-tetrachloro-bis-(pyridine)-rhenium(IV)

    NASA Astrophysics Data System (ADS)

    Mroziński, J.; Kochel, A.; Lis, T.

    2002-06-01

    trans-Tetrachloro-bis-(pyridine)-rhenium(IV) crystals were obtained by reaction of (pyH)2ReCl6 with pyridine in a sealed tube. The title compound crystallizes in the monoclinic space group C2/m with Z=2. The Re atom has special position of site symmetry 2/m. The environment about the Re atoms can be described as a slightly distorted octahedron with pyridine ligands occupying axial positions and four chloride ligands in the equatorial plane. Magnetic susceptibility measurements over the temperature range of 1.72-300 K were carried out using a SQUID magnetometer. The magnetic interactions are antiferromagnetic with the Néel point at 9.2 K.

  17. A mono-diazenide complex from perrhenate: toward a new core for rhenium radiopharmaceuticals.

    PubMed

    Cowley, Andrew R; Dilworth, Jonathan R; Donnelly, Paul S

    2003-02-24

    A new method for the synthesis of low to intermediate oxidation state rhenium complexes containing a bifunctional ligand has been developed. Reaction of [ReO(4)](-) with substituted phenylhydrazines and triphenylphosphine in acetonitrile in the presence of HCl allows the isolation of [ReCl(2)(NNC(6)H(4)-4-R)(NCCH(3))(PPh(3))(2)] (where R = OCH(3), Cl, or CO(2)CH(3)). The substituted hydrazine acts as both a reductant and source of a monodentate diazenide ligand. The compounds have all been characterized in the solid state by X-ray crystallography and in the solution state by NMR, electrospray mass spectrometry, and HPLC. Cyclic voltammetry measurements show that the mono-diazenide complexes undergo a reversible oxidation.

  18. Rhenium-188: Availability from the W-188/Re-188 Generator and Status of Current Applications

    SciTech Connect

    Pillai, M R A; Dash, A; Knapp Jr, Russ F

    2012-01-01

    Rhenium-188 is one of the most readily available generator derived and useful radionuclides for therapy emitting - particles (2.12 MeV, 71.1% and 1.965 MeV, 25.6%) and imageable gammas (155 KeV, 15.1%). The 188W/188Re generator is an ideal source for the long term (4-6 months) continuous availability of no carrier added (nca) 188Re suitable for the preparation of radiopharmaceuticals for radionuclide therapy. The challenges associated with the double neutron capture route of production of the parent 188W radionuclide have been a major impediment in the progress of application of 188Re. Tungsten-188 of adequate specific activity can be prepared only in 2-3 of the high flux reactors operating in the World. Several useful technologies have been developed for the preparation of clinical grade 188W/188Re generator. Since the specific activity of 188W used in the generator is relatively low (<5 Ci/g), the eluted 188ReO4- can have low radioactive concentration often insufficient for radiopharmaceutical preparation. However, several efficient post elution concentration techniques have been developed that yield clinically useful 188ReO4-. Rhenium-188 has been used for the preparation of therapeutic radiopharmaceuticals for the management of diseases such as bone metastasis, rheumatoid arthritis and primary cancers. Several early phase clinical studies using radiopharmaceuticals based on 188Re-labeled phosphonates, antibodies, peptides, lipiodol and particulates have been reported. This article reviews the availability, and use of188Re including a discussion of why broader use of 188Re has not progressed as ecpected as a popular radionuclide for therapy.

  19. Tracing oxidative weathering from the Andes to the lowland Amazon Basin using dissoved rhenium

    NASA Astrophysics Data System (ADS)

    Dellinger, M.; Hilton, R. G.; West, A. J.; Torres, M.; Burton, K. W.; Clark, K. E.; Baronas, J. J.

    2016-12-01

    Over long timescales (>105 yrs), the abundance of carbon dioxide (CO2) in the atmosphere is determined by the balance of the major carbon sources and sinks. Among the major carbon sources, the oxidation of organic carbon contained within sedimentary rocks ("petrogenic" carbon, or OCpetro) is thought to result in CO2 emission of similar magnitude to that released by volcanism. Rhenium (Re) has been proposed as a proxy for tracing OCpetro oxidation. Here we investigate the source, behavior and flux of dissolved and particulate rhenium (Re) in the Madre de Dios watershed (a major Andean tributary of the Amazon River) and the lowlands, aiming to characterize the behavior of Re in river water and quantify the flux of CO2 released by OCpetro oxidation. Measured Re concentrations in Andean rivers range from 0.07 to 1.55 ppt. In the Andes, Re concentration do not change significantly with water discharge, whereas in the lowlands, Re concentration decrease at high water discharge. Mass balance calculation show that more than 70% of the dissolved Re is sourced from the oxidation of OCpetro the Andes-floodplain system. We calculate dissolved Re flux over a hydrological year to estimate the rates of oxidative weathering, and the associated CO2 release from OCpetro. Rates are high in the Andean headwaters, consistent with estimates from other mountain rivers with similar rates of physical erosion. We find evidence that a significant amount of additional oxidation (Re flux) happens during floodplain transport. These results have important implications for improving our understanding of the source and processes controlling Re in rivers, and allowing us to quantify long-term OCpetro cycling in large river basins.

  20. Rhenium Alloys as Ductile Substrates for Diamond Thin-Film Electrodes

    PubMed Central

    Halpern, Jeffrey M.; Martin, Heidi B.

    2014-01-01

    Molybdenum-rhenium (Mo/Re) and tungsten-rhenium (W/Re) alloys were investigated as substrates for thin-film, polycrystalline boron-doped diamond electrodes. Traditional, carbide-forming metal substrates adhere strongly to diamond but lose their ductility during exposure to the high-temperature (1000°C) diamond, chemical vapor deposition environment. Boron-doped semi-metallic diamond was selectively deposited for up to 20 hours on one end of Mo/Re (47.5/52.5 wt.%) and W/Re (75/25 wt.%) alloy wires. Conformal diamond films on the alloys displayed grain sizes and Raman signatures similar to films grown on tungsten; in all cases, the morphology and Raman spectra were consistent with well-faceted, microcrystalline diamond with minimal sp2 carbon content. Cyclic voltammograms of dopamine in phosphate-buffered saline (PBS) showed the wide window and low baseline current of high-quality diamond electrodes. In addition, the films showed consistently well-defined, dopamine electrochemical redox activity. The Mo/Re substrate regions that were uncoated but still exposed to the diamond-growth environment remained substantially more flexible than tungsten in a bend-to-fracture rotation test, bending to the test maximum of 90° and not fracturing. The W/Re substrates fractured after a 27° bend, and the tungsten fractured after a 21° bend. Brittle, transgranular cleavage fracture surfaces were observed for tungsten and W/Re. A tension-induced fracture of the Mo/Re after the prior bend test showed a dimple fracture with a visible ductile core. Overall, the Mo/Re and W/Re alloys were suitable substrates for diamond growth. The Mo/Re alloy remained significantly more ductile than traditional tungsten substrates after diamond growth, and thus may be an attractive metal substrate for more ductile, thin-film diamond electrodes. PMID:25404788

  1. Catalytic Activity of Platinum Monolayer on Iridium and Rhenium Alloy Nanoparticles for the Oxygen Reduction Reaction

    SciTech Connect

    Karan, Hiroko I.; Sasaki, Kotaro; Kuttiyiel, Kurian; Farberow, Carrie A.; Mavrikakis, Manos; Adzic, Radoslav R.

    2012-05-04

    A new type of electrocatalyst with a core–shell structure that consists of a platinum monolayer shell placed on an iridium–rhenium nanoparticle core or platinum and palladium bilayer shell deposited on that core has been prepared and tested for electrocatalytic activity for the oxygen reduction reaction. Carbon-supported iridium–rhenium alloy nanoparticles with several different molar ratios of Ir to Re were prepared by reducing metal chlorides dispersed on Vulcan carbon with hydrogen gas at 400 °C for 1 h. These catalysts showed specific electrocatalytic activity for oxygen reduction reaction comparable to that of platinum. The activities of PtML/PdML/Ir2Re1, PtML/Pd2layers/Ir2Re1, and PtML/Pd2layers/Ir7Re3 catalysts were, in fact, better than that of conventional platinum electrocatalysts, and their mass activities exceeded the 2015 DOE target. Our density functional theory calculations revealed that the molar ratio of Ir to Re affects the binding strength of adsorbed OH and, thereby, the O2 reduction activity of the catalysts. The maximum specific activity was found for an intermediate OH binding energy with the corresponding catalyst on the top of the volcano plot. The monolayer concept facilitates the use of much less platinum than in other approaches. Finally, the results with the PtML/PdML/Ir2Re electrocatalyst indicate that it is a promising alternative to conventional Pt electrocatalysts in low-temperature fuel cells.

  2. Rhenium-188: availability from the (188)W/(188)Re generator and status of current applications.

    PubMed

    Pillai, M R A; Dash, Ashutosh; Knapp, F F

    2012-07-01

    Rhenium-188 is one of the most readily available generator derived and useful radionuclides for therapy emitting β(-) particles (2.12 MeV, 71.1% and 1.965 MeV, 25.6%) and imageable gammas (155 keV, 15.1%). The (188)W/(188)Re generator is an ideal source for the long term (4-6 months) continuous availability of no carrier added (nca) (188)Re suitable for the preparation of radiopharmaceuticals for radionuclide therapy. The challenges associated with the double neutron capture route of production of the parent (188)W radionuclide have been a major impediment in the progress of application of (188)Re. Tungsten-188 of adequate specific activity can be prepared only in 2-3 of the high flux reactors operating in the World. Several useful technologies have been developed for the preparation of clinical grade (188)W/(188)Re generators. Since the specific activity of (188)W used in the generator is relatively low 185 GBq( < 5 Ci)/g], the eluted (188)ReO(4)(-) can have low radioactive concentration often insufficient for radiopharmaceutical preparation. However, several efficient post elution concentration techniques have been developed that yield clinically useful (188)ReO(4)(-) solutions. Rhenium-188 has been used for the preparation of therapeutic radiopharmaceuticals for the management of diseases such as bone metastasis, rheumatoid arthritis and primary cancers. Several early phase clinical studies using radiopharmaceuticals based on (188)Re-labeled phosphonates, antibodies, peptides, lipiodol and particulates have been reported. This article reviews the availability and use of (188)Re including a discussion of why broader use of (188)Re has not progressed as expected as a popular radionuclide for therapy.

  3. Rhenium Alloys as Ductile Substrates for Diamond Thin-Film Electrodes.

    PubMed

    Halpern, Jeffrey M; Martin, Heidi B

    2014-02-01

    Molybdenum-rhenium (Mo/Re) and tungsten-rhenium (W/Re) alloys were investigated as substrates for thin-film, polycrystalline boron-doped diamond electrodes. Traditional, carbide-forming metal substrates adhere strongly to diamond but lose their ductility during exposure to the high-temperature (1000°C) diamond, chemical vapor deposition environment. Boron-doped semi-metallic diamond was selectively deposited for up to 20 hours on one end of Mo/Re (47.5/52.5 wt.%) and W/Re (75/25 wt.%) alloy wires. Conformal diamond films on the alloys displayed grain sizes and Raman signatures similar to films grown on tungsten; in all cases, the morphology and Raman spectra were consistent with well-faceted, microcrystalline diamond with minimal sp(2) carbon content. Cyclic voltammograms of dopamine in phosphate-buffered saline (PBS) showed the wide window and low baseline current of high-quality diamond electrodes. In addition, the films showed consistently well-defined, dopamine electrochemical redox activity. The Mo/Re substrate regions that were uncoated but still exposed to the diamond-growth environment remained substantially more flexible than tungsten in a bend-to-fracture rotation test, bending to the test maximum of 90° and not fracturing. The W/Re substrates fractured after a 27° bend, and the tungsten fractured after a 21° bend. Brittle, transgranular cleavage fracture surfaces were observed for tungsten and W/Re. A tension-induced fracture of the Mo/Re after the prior bend test showed a dimple fracture with a visible ductile core. Overall, the Mo/Re and W/Re alloys were suitable substrates for diamond growth. The Mo/Re alloy remained significantly more ductile than traditional tungsten substrates after diamond growth, and thus may be an attractive metal substrate for more ductile, thin-film diamond electrodes.

  4. Identification of rhenium donors and sulfur vacancy acceptors in layered MoS2 bulk samples

    NASA Astrophysics Data System (ADS)

    Brandão, F. D.; Ribeiro, G. M.; Vaz, P. H.; González, J. C.; Krambrock, K.

    2016-06-01

    MoS2 monolayers, a two-dimensional (2D) direct semiconductor material with an energy gap of 1.9 eV, offer many opportunities to be explored in different electronic devices. Defects often play dominant roles in the electronic and optical properties of semiconductor devices. However, little experimental information about intrinsic and extrinsic defects or impurities is available for this 2D system, and even for macroscopic 3D samples for which MoS2 shows an indirect bandgap of 1.3 eV. In this work, we evaluate the nature of impurities with unpaired spins using electron paramagnetic resonance (EPR) in different geological macroscopic samples. Regarding the fact that monolayers are mostly obtained from natural crystals, we expect that the majority of impurities found in macroscopic samples are also randomly present in MoS2 monolayers. By EPR at low temperatures, rhenium donors and sulfur vacancy acceptors are identified as the main impurities in bulk MoS2 with a corresponding donor concentration of about 108-12 defects/cm2 for MoS2 monolayer. Electrical transport experiments as a function of temperature are in good agreement with the EPR results, revealing a shallow donor state with an ionization energy of 89 meV and a concentration of 7 × 1015 cm-3, which we attribute to rhenium, as well as a second deeper donor state with ionization energy of 241 meV with high concentration of 2 × 1019 cm-3 and net acceptor concentration of 5 × 1018 cm-3 related to sulfur vacancies.

  5. Design and synthesis of site directed maleimide bifunctional chelators for technetium and rhenium.

    PubMed

    Banerjee, Sangeeta Ray; Schaffer, Paul; Babich, John W; Valliant, John F; Zubieta, Jon

    2005-12-21

    A new family of heterobifunctional linkers (L1-L9) containing a terminus consisting of a tridentate donor set for coordination of the {M(CO)(3)}(+) core (M = Tc, Re), and a thiol reactive maleimide group has been prepared conveniently and in high yield under Mitsunobu reaction conditions by the coupling of an appropriate alcohol derivative with maleimide. The rhenium complexes [Re(CO)(3)(Lx)]Br (x= 1-9) were prepared in good yields from the reactions of the ligands and (NEt(4))(2)[Re(CO)(3)Br(3)] in refluxing methanol. The ligands and their Re complexes were characterized by (1)H and (13)C NMR, IR, and ESI-MS. Ligand L4 and [Re(CO)(3)(L5)]Br have been structurally characterized by X-ray crystallography. Photoexcitation of solutions of the complexes [Re(CO)(3)(Lx)]Br (x= 4-6) gives rise to intense and prolonged luminescence at room temperature (fluorescence lifetimes of ca. 16 micros). The ligands and their Re complexes react smoothly at the maleimide linker with sulfhydryl groups of peptides and proteins at room temperature in phosphate-buffered saline (PBS, pH 7.4) to form stable thioether bioconjugates. The photoluminescence properties of the labeled conjugates are similar to those of the parent complexes, but with even longer lifetimes. The ligands can also be labeled at room temperature with (99m)Tc to give chemically robust complexes. The corresponding hydrazinonicotinamide derivative N-[5-(6'-hydrazinopyridine-3'-carbonyl)aminopentyl]maleimide (L10) was also prepared. While coupling of L10 to cysteine ethylester and synthesis of the rhenium derivative [ReCl(3)(HYNIC-maleimide)(2)] were successfully accomplished, attempts to couple [ReCl(3)(HYNIC-maleimide)(2)] to glutathione or BSA yielded intractable mixtures.

  6. Dose Effect of Rhenium (I)-diselenoether as Anticancer Drug in Resistant Breast Tumor-bearing Mice After Repeated Administrations.

    PubMed

    Collery, Philippe; Santoni, François; Ciccolini, Joseph; Tran, Thi Ngoc Nga; Mohsen, Ahmed; Desmaele, Didier

    2016-11-01

    Rhenium (I)-diselenoether has shown promising antiproliferative efficacy in both in vitro and in vivo models. However, the maximal tolerated dose and dose-effect relationships have not been fully addressed for this compound. Here, we evaluated the tolerance and efficacy of three dose-levels (namely 10, 40 and 100 mg/kg) intraperitoneally administered daily over 28 days in mice bearing the resistant MDA-MB231 breast cancer cell line. The upper dose was found to be toxic and was reduced to 60 mg/kg. The 10 mg/kg dose well tolerated, whereas 40 mg/kg was associated with 10% mortality (LD10). Both 10 and 40 mg/kg dosing achieved a significantly similar regression of tumor growth compared with untreated animals. This study suggests that 10 mg/kg daily is the recommended dose for rhenium (I) diselenoether. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  7. Substituted ethan phosphonic acid esters as reagents for the separation of molybdenum from rhenium by solvent extraction.

    PubMed

    Jordanov, N; Mareva, S; Borisov, G; Jordanov, B

    1968-02-01

    New esters of the ethan phosphonic acids have been synthesized and their extraction properties studied with respect to Mo(VI), Re(VII), Fe(III),Au(III),Tl(III) and Sb(V). A possibility is shown for the analytical separation of molybdenum from rhenium (beta = 700). The state of these new extraction agents in carbon tetrachloride solution, and the mechanism of the extraction processes, have been investigated by means of infrared spectra.

  8. Radiosynovectomy in haemophilic synovitis of elbows and ankles: Is the effectiveness of yttrium-90 and rhenium-186 different?

    PubMed

    Rodriguez-Merchan, E C; De La Corte-Rodriguez, H

    2016-04-01

    Radiosynovectomy (RS) reduces the number of haemarthroses and the synovial size in chronic haemophilic synovitis. The purpose of this study was to quantitatively compare the effectiveness of two types of RS (yttrium-90 vs. rhenium-186) in terms of the objective improvement of haemarthroses and synovial size. Seventy RSs were performed in 70 joints (44 elbows, 26 ankles) of 70 haemophiliacs diagnosed with chronic synovitis. Yttrium-90 was used in 21 joints and rhenium-186 was used in 49 joints. The mean patient age was 20.61 years. RS resulted in significant improvement in the three variables studied (six months before RS vs. six months after RS), namely in the number of episodes of haemarthrosis (67.8% improvement); the size of the synovium as measured by means of a clinical scale (43.8% improvement) and imaging techniques in millimetres (26.7% improvement). We did not find significant statistical differences between yttrium-90 and rhenium-186 regarding their efficacy. No correlation was found between the results and other variables: age, joint (ankle or elbow), presence or absence of radiological involvement, type of haemophilia (A or B), grade of haemophilia (mild, moderate or severe), previous haematological treatment (on demand or prophylaxis), and the presence or absence of inhibitor Yttrium-90 RS and rhenium-186 RS were equally effective in reducing the number of haemarthroses and the size of the synovium in ankles and elbows in the short-term (6 months). No correlation was found between the results and other patients' characteristics. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Monte Carlo Criticality Analysis of Simple Geometrics COntaining Tungsten Rhenium Alloys Engrained with Uranium Dioxide and Uranium Mononitride

    SciTech Connect

    Jonathan A. Webb; Indrajit Charit

    2011-08-01

    The critical mass and dimensions of simple geometries containing highly enriched uraniumdioxide (UO2) and uraniummononitride (UN) encapsulated in tungsten-rhenium alloys are determined using MCNP5 criticality calculations. Spheres as well as cylinders with length to radius ratios of 1.82 are computationally built to consist of 60 vol.% fuel and 40 vol.% metal matrix. Within the geometries the uranium is enriched to 93 wt.% uranium-235 and the rhenium content within the metal alloy was modeled over a range of 0 to 30 at.%. The spheres containing UO2 were determined to have a critical radius of 18.29 cm to 19.11 cm and a critical mass ranging from 366 kg to 424 kg. The cylinders containing UO2 were found to have a critical radius ranging from 17.07 cm to 17.844 cm with a corresponding critical mass of 406 kg to 471 kg. Spheres engrained with UN were determined to have a critical radius ranging from 14.82 cm to 15.19 cm and a critical mass between 222 kg and 242 kg. Cylinders which were engrained with UN were determined to have a critical radius ranging from 13.811 cm to 14.155 cm with a corresponding critical mass of 245 kg to 267 kg. The critical geometries were also computationally submerged in a neutronaically infinite medium of fresh water to determine the effects of rhenium addition on criticality accidents due to water submersion. The monte carlo analysis demonstrated that rhenium addition of up to 30 at.% can reduce the excess reactivity due to water submersion by up to $5.07 for UO2 fueled cylinders, $3.87 for UO2 fueled spheres and approximately $3.00 for UN fueled spheres and cylinders.

  10. Development of MAG3 p-nitrophenyl ester for technetium-99m and rhenium-188 labeling of amines and peptides

    SciTech Connect

    Guhlke, S.; Diekmann, D.; Biersack, H.J.; Zamora, P.O.; Knapp, F.F. Jr.

    1994-09-01

    Conjugate labeling by active ester chemistry is a well-established method for labeling peptides and proteins with technetium and rhenium. The easy preparation and high conjugations yields presented in this paper show that both {sup 188}Re and {sup 99m}Tc-MAG{sub 3} p-nitrophenyl esters are promising agents for labeling a wide range of biomolecules for radio therapy or diagnostic imaging.

  11. Photoinduced hydrogen evolution in supramolecular devices with a rhenium photosensitizer linked to FeFe-hydrogenase model complexes.

    PubMed

    Liu, Jianhui; Jiang, Weina

    2012-08-28

    Coordination of the pyridyl-attached diiron azadithiolate hexacarbonyl complexes (2 and 3) through the pyridyl nitrogen to the Re on 10-phenanthroline rhenium (5a) and 2,9-diphenyl-1,10-phenanthroline rhenium (5b) forms novel [Re-Fe] complexes 7a, 7b and 8 respectively. Under visible light illumination using triethylamine as a sacrificial electron donor and [Re-Fe] type complexes (7a, 7b or 8) as catalysts, remarkably increased efficiency was observed for photoinduced hydrogen production with a turnover number reaching 11.8 from complex 7a and 8.75 from 7b. To the best of our knowledge, these are the best values compared to other [Re-Fe] photocatalysts reported so far. In contrast to the parent molecules, the turnover number by the intermolecular combination of complexes 6a and 2 showed a value of 5.23, and that from 6b and 2 is 3.8, while no H(2) was detected from 8a and 3 under the same experimental conditions. Obviously, the intramolecular combination of rhenium(I) and [2Fe2S] as a catalyst is promising for efficient H(2) evolution, and it is better than the intermolecular multi-component system.

  12. New rhenium complexes with ciprofloxacin as useful models for understanding the properties of [99mTc]-ciprofloxacin radiopharmaceutical.

    PubMed

    Lecina, Joan; Cortés, Pilar; Llagostera, Montserrat; Piera, Carlos; Suades, Joan

    2014-07-01

    Rhenium complexes with the antibiotic ciprofloxacin have been prepared to be studied as models of technetium radiopharmaceuticals. With this aim, the new rhenium complexes 1 {[ReO(Cpf)2]Cl}, 2 {[ReO(CpfH)2]Cl3} and 3 {fac-[Re(CO)3(H2O)(Cpf)]} with ciprofloxacin (CpfH=ciprofloxacin; Cpf=conjugated base of ciprofloxacin) have been synthesised and characterised by elemental analyses, IR, NMR ((1)H, (19)F and (13)C CP-MAS) spectroscopy, as well as MS measurements. All spectroscopic data are consistent with the coordination of ciprofloxacin in all these complexes through the carbonyl and the carboxylate oxygen atoms with the formation of a six member chelate ring. The study of a Tc-ciprofloxacin solution by ESI-MS reveals the presence of [TcO(Cpf)2](+) cations, which agrees with the hypothesis that complexes 1 and 2 can be seen as model rhenium complexes of this radiopharmaceutical. Antimicrobial and DNA gyrase inhibition studies performed with complexes 2 and 3 have shown a very similar behaviour between complex 2 and the free antibiotic, whereas complex 3 exhibit a lower antimicrobial activity. Based on a joint analysis of the data reported in the literature and the chemical and biological results obtained in this study, a tentative proposal to explain some aspects of the behaviour of Tc-ciprofloxacin radiopharmaceutical has been made. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Water-soluble phosphines for direct labeling of peptides with technetium and rhenium: insights from electrospray mass spectrometry.

    PubMed

    Greenland, William E P; Blower, Philip J

    2005-01-01

    Direct labeling of salmon calcitonin (sCT) is possible in one step using water-soluble phosphines (sulfonated triphenylphosphines) as the reducing agent both for disulfide and for pertechnetate. Phosphines were the most efficient reducing agent for disulfide bonds among those examined. The phosphines both reduced the pertechnetate to Tc(III), and contributed to the technetium coordination sphere in the labeled product. In contrast, the phosphines did not reduce rhenium below oxidation state V, nor did they participate in the rhenium coordination sphere in the labeled peptide. Instead, the expected oxorhenium(V) moiety was incorporated. Both Tc and Re labeling processes gave rise to dimers with two peptides linked by the metal center, as well as simple monomeric species. Positive mode electrospray mass spectrometry not only revealed the presence of phosphine bound to technetium and oxygen bound to rhenium in the metallopeptides but also revealed the oxidation states of the metals. Electrospray mass spectrometry is proving to be an exceptionally valuable technique for characterizing radiopharmaceuticals. Although the one-step direct labeling method described gives mixed products and poor receptor affinity when applied to the small peptide sCT, it might be readily adapted to monoclonal antibodies.

  14. Hydroxyapatite coatings.

    PubMed

    Lacefield, W R

    1988-01-01

    Four coating techniques were evaluated to determine which is most suitable for producing a dense, highly adherent coating onto metallic and ceramic implant materials. Two of the selected coating methods have serious limitations for use in this particular application, and did not meet the specified criteria for satisfactory coating as defined in the initial stages of the study. For example, the dip coating-sintering technique was judged to be unsatisfactory because of the adverse effect of the high-temperature sintering cycle on the mechanical properties of the metallic substrate materials. These materials could not be used in load-bearing applications because of the excessive grain growth and loss of the wrought structure of both the commercially pure Ti and Ti-6Al-4V substrates, and the loss of ductility in the cast Co-Cr-Mo alloy. Another area of concern was that bond strength between the HA coating and the substrate was not high enough to insure that interfacial failure would not occur during the lifetime of the implant. The immersion-coating technique, in which the metal substrate is immersed into the molten ceramic, was shown in a previous study to be the best method of coating a bioreactive glass onto a Co-Cr-Mo implant. Heating HA above its melting temperature, however, caused undesired compositional and structural changes, and upon solidification very limited adherence between the modified ceramic and substrate material occurred under the conditions of this study. The HIP technique, in which the Ti powder substrate and the HA powder coating are sintered together in a high-pressure autoclave, shows great promise for the fabrication of high-quality composite implants. Initial studies have indicated that high-density Ti substrates with a small grain size that are well bonded to a dense HA coating can be produced under optimum conditions. Sintering and densification additives, such as SiO2 powder, do not appear to be necessary. The main drawback to this

  15. Molecular Rhenium(V) Oxotransferases: Oxidation of Thiols to Disulfides with Sulfoxides. The Case of Substrate-Inhibited Catalysis.

    PubMed

    Abu-Omar, Mahdi M.; Khan, Saeed I.

    1998-09-21

    Re(O)Cl(3)(PPh(3))(2), 1, and Re(O)Cl(3)(OPPh(3))(Me(2)S), 2, catalyze the oxidation of thiols to disulfides with sulfoxides under mild conditions. Catalyst 1 exhibits an induction period which features PPh(3) oxidation to OPPh(3) prior to disulfide formation. This lag is absent when 2 is the catalyst precursor. Otherwise, 1 and 2 display comparable kinetics and concentration dependencies. The catalytic reactions are first-order in catalyst, inhibited by thiol, and first-order in sulfoxide at low sulfoxide concentrations. Thiol inhibits the oxygen-transfer reaction because it competes with sulfoxide for coordination on rhenium. Sulfoxides must bind to rhenium in order to be activated for oxo transfer. Ligand substitution reactions of 1 and 2 display kinetics that are consistent with a dissociative (D) mechanism: the substitution rate is zero-order in entering ligand and inhibited by departing ligand. The first-order rate constant for the formation of a 5-coordinate intermediate is 0.06 s(-)(1). As the sulfoxide concentration is increased, the reaction rate increases to reach a maximum and then begins to decline. The catalytic turnover rate at optimal conditions (maximum k(cat) for PhS(O)Me is 180 h(-)(1)) approaches the rate of ligand substitution in these rhenium(V) complexes. Rate retardation at high sulfoxide concentrations is due to catalyst deactivation; sulfoxides oxidize the rhenium(V) catalyst to ReO(4)(-), which is inactive. Dimethyl sulfoxide (DMSO) is more efficient than aryl sulfoxides at oxidizing the catalyst, a fact that could be rationalized by the thermodynamics of S-O bond strength. Thus, aryl sulfoxides, such as PhS(O)Me, appear to be more reactive than alkyl ones. The oxygen-transfer reaction, therefore, is not involved in the rate-controlling step and the rate is limited by ligand substitution. The rhenium(V) catalyst in these reactions acts as a Lewis acid and activates the sulfoxide via coordination: the sulfoxide ligand and not the metal is

  16. Regulatory Aspects of Coatings

    USDA-ARS?s Scientific Manuscript database

    This chapter gives a history of the development and uses of edible coating regulations, detailed chapters on coating caracteristics, determination of coating properties, methods for making coatings, and discription of coating film formers (polysaccharieds, lipids, resins, proteins). The chapter also...

  17. Final Test Report: Hexavalent Chrome Free Coatings for Electronics Electromagnetic Interference (EMI) Shielding Effectiveness (SE)

    NASA Technical Reports Server (NTRS)

    Kessel, Kurt R.

    2016-01-01

    The test results for Salt Spray Resistance, Static Heat and Humidity and Marine Environment can be found in Sections 3.1.3.3, 3.1.4.3 and 3.1.5.3 respectively. In summary, both the Metalast TCP and SurTec 650 Type 2 conversion coatings perform very similar to the incumbent Type 1 conversion coating against both 6061 and 5052 aluminum under all three test conditions. Significant prior work was performed to select the aluminum and conversion coating included within this test cycle; Reference - NASA GSDO Program Hexavalent Chrome Alternatives Final Pretreatments Test Report Task Order: NNH12AA45D September 01, 2013. As illustrated in the data, the 6061 aluminum panels SLIGHTLY out-performed the 5052 aluminum panels. Individual shielding effectiveness graphs for each panel are included within Appendix C and D. One other notable effect found during review of the data is that the Test Panels exposed to B117 Salt Fog reduced in shielding effectiveness significantly more than the Marine Environment Test Panels. The shielding effectiveness of the Marine Test Panels was approximately 20dB higher than the Test Panels that underwent B117 Salt Fog Exposure. The intent of this evaluation was not to maximize shielding effectiveness values. The same Parker Chomerics Cho-Seal 6503 gasket material was used for all panels with aluminum and conversion coating variants. A typical EMI gasket design for corrosive environments would be done quite differently. The intent was to execute a test that would provide the best possible evaluation of different aluminum materials and conversion coatings in corrosive environments. The test program achieved this intent. The fact that the two aluminums and two Type II conversion coatings performed similar to the incumbent Type 1 conversion coating is a positive outcome. It was desired to have an outcome that further differentiation the performance of two aluminum types and two conversion coating types but this could not be extracted by the test

  18. Intracellular distribution and stability of a luminescent rhenium(I) tricarbonyl tetrazolato complex using epifluorescence microscopy in conjunction with X-ray fluorescence imaging

    SciTech Connect

    Wedding, Jason L.; Harris, Hugh H.; Bader, Christie A.; Plush, Sally E.; Mak, Rachel; Massi, Massimiliano; Brooks, Douglas A.; Lai, Barry; Vogt, Stefan; Werrett, Melissa V.; Simpson, Peter V.; Skelton, Brian W.; Stagni, Stefano

    2016-11-23

    Optical fluorescence microscopy was used in conjunction with X-ray fluorescence microscopy to monitor the stability and intracellular distribution of the luminescent rhenium(I) complex fac-[Re(CO)3(phen)L], where phen = 1,10-phenathroline and L = 5-(4-iodophenyl)tetrazolato, in 22Rv1 cells. The rhenium complex showed no signs of ancillary ligand dissociation, a conclusion based on data obtained via X-ray fluorescence imaging aligning iodine and rhenium distributions. A diffuse reticular localisation was detected for the complex, in the nuclear/perinuclear region of cells, by either optical or X-ray fluorescence techniques. Furthermore, X-ray fluorescence also showed that the Re-I complex disrupted the homeostasis of some biologically relevant elements, such as chlorine, potassium and zinc.

  19. Atomic Layer Deposition of Rhenium-Aluminum Oxide Thin Films and ReOx Incorporation in a Metal-Organic Framework.

    PubMed

    Rimoldi, Martino; Hupp, Joseph T; Farha, Omar K

    2017-10-11

    Methyltrioxorhenium (ReO3Me) is introduced as the first rhenium atomic layer deposition (ALD) precursor and used to grow rhenium-aluminum oxide thin films in combination with trimethylaluminum (TMA-AlMe3). The growth rate of the smooth Re-Al oxide films, with general stoichiometry RexAlyO3x, has been monitored by in situ quartz crystal microbalance (QCM) and ex situ ellipsometry, and found to be 3.2 Å/cycle. X-ray photoelectron spectroscopy (XPS) revealed the mixed valent composition of the film with Re(III) species being the main component. In addition, ReO3Me has been successfully used to deposit rhenium oxide in NU-1000, a mesoporous zirconium-based metal-organic framework (MOF). The metalated MOF was found to retain porosity and crystallinity and to be catalytically active for ethene hydrogenation.

  20. Intracellular distribution and stability of a luminescent rhenium(I) tricarbonyl tetrazolato complex using epifluorescence microscopy in conjunction with X-ray fluorescence imaging

    DOE PAGES

    Wedding, Jason L.; Harris, Hugh H.; Bader, Christie A.; ...

    2016-11-23

    Optical fluorescence microscopy was used in conjunction with X-ray fluorescence microscopy to monitor the stability and intracellular distribution of the luminescent rhenium(I) complex fac-[Re(CO)3(phen)L], where phen = 1,10-phenathroline and L = 5-(4-iodophenyl)tetrazolato, in 22Rv1 cells. The rhenium complex showed no signs of ancillary ligand dissociation, a conclusion based on data obtained via X-ray fluorescence imaging aligning iodine and rhenium distributions. A diffuse reticular localisation was detected for the complex, in the nuclear/perinuclear region of cells, by either optical or X-ray fluorescence techniques. Furthermore, X-ray fluorescence also showed that the Re-I complex disrupted the homeostasis of some biologically relevant elements, suchmore » as chlorine, potassium and zinc.« less

  1. Search for a more adequate test to predict the long-term migration from the PVC gaskets of metal lids into oily foods in glass jars.

    PubMed

    Graubardt, Nadine; Biedermann, Maurus; Fiselier, Katell; Bolzoni, Luciana; Pedrelli, Turno; Cavalieri, Chiara; Simoneau, Cathérine; Grob, Koni

    2009-07-01

    As shown previously, the conventional testing procedure for simulating long-term migration from the gaskets of metal closures into oily foods does not adequately reflect reality. It appears to be impossible to accelerate migration to the extent that the situation at the end of the shelf life of a product can be anticipated in a few days or weeks. Therefore, we investigated whether long-term migration could be extrapolated from migration rates determined for new lids. Jars were kept in the normal upright position. Since heat treatment may have a strong temporary impact, migration during the initial heating for pasteurization or sterilization and storage at ambient temperature were determined using different lids. Commercial products were recalled from sales points throughout Europe to determine the real migration over extended periods of time and for jars with differing histories. This migration was compared with data from the short-term testing to investigate whether an empirical relationship could be derived. The results show that the short-term test enables the comparison of lids and plasticizers in the initial phase of migration, but that long-term extrapolation presupposes more complex kinetic modeling. The results also demonstrate that the legal relevance of "official" testing methods should be reconsidered to avoid conflict when food contact materials comply with migration limits in the test but not in actual application.

  2. A design of backing seat and gasket assembly in diamond anvil cell for accurate single crystal x-ray diffraction to 5 GPa.

    PubMed

    Komatsu, K; Kagi, H; Yasuzuka, T; Koizumi, T; Iizuka, R; Sugiyama, K; Yokoyama, Y

    2011-10-01

    We designed a new cell assembly of diamond anvil cells for single crystal x-ray diffraction under pressure and demonstrate the application of the cell to the crystallographic studies for ice VI and ethanol high-pressure (HP) phase at 0.95(5) GPa and 1.95(2) GPa, respectively. The features of the assembly are: (1) the platy anvil and unique-shaped backing seat (called as "Wing seat") allowing the extremely wide opening angle up to ±65°, (2) the PFA-bulk metallic glass composite gasket allowing the easy attenuation correction and less background. Thanks to the designed assembly, the R(int) values after attenuation corrections are fairly good (0.0125 and 0.0460 for ice VI and ethanol HP phase, respectively), and the errors of the refined parameters are satisfactory small even for hydrogen positions, those are comparable to the results which obtained at ambient conditions. The result for ice VI is in excellent agreement with the previous study, and that for ethanol HP phase has remarkable contributions to the revision to its structure; the H12 site, which makes gauche molecules with O1, C2, and C3 sites, may not exist so that only trans conformers are present at least at 1.95(2) GPa. The accurate intensities using the cell assembly allow us to extract the electron density for ethanol HP phase by the maximum entropy method.

  3. Rhenium(I) Carbonyl Complexes of 2,4,6-Tris(2-pyridyl)-1,3,5-triazine (TPT). Rhenium(I)-Promoted Methoxylation of the Triazine Ring Carbon Atom in Dinuclear Rhenium Complexes

    PubMed Central

    Chen, Xiaoyuan; Femia, Frank J.; Babich, John W.; Zubieta, Jon A.

    2010-01-01

    2,4,6-Tris(2-pyridyl)-1,3,5-triazine (TPT) bridged dinuclear rhenium(I) tricarbonyl halide complexes with the composition (μ-TPT)[ReX(CO)3]2 (3, X = Cl; 4, X = Br) can be made either by one-pot reaction of TPT with 2 equiv of [ReX(CO)5] (X = Cl and Br) in chloroform or by reacting mononuclear [ReX(CO)3(TPT)] 2 (1, X = Cl; 2, X = Br) with an excess amount of [ReX(CO)5]. Crystal data are as follows. 1: monoclinic, P21/c, a = 11.751(1) Å, b = 11.376(1) Å, c = 15.562(2) Å, β = 103.584(2)°, V = 2022.0(4) Å3, Z = 4. 2: monoclinic, P21/c, a = 11.896(1) Å, b = 11.396(1) Å, c = 15.655(1) Å, β = 104.474(2)°, V = 2054.9(3) Å3, Z = 4. 3: triclinic, P1‒, a = 11.541(2) Å, b = 12.119(2) Å, c = 13.199(2) Å, α = 80.377(2)°, β = 76.204(3)°, γ = 66.826-(2)°, V = 1642.5(4) Å3, Z ) 2. Crystals of 4 crystallized from acetone: triclinic, P1‒, a = 11.586(5) Å, b = 12.144(5) Å, c = 13.364(6) Å, α = 80.599(7)°, β = 76.271(8)°, γ = 67.158(8)°, V = 1678.0(12) Å3, Z = 2. Crystals of 4′ are obtained from CH2Cl2–pentane solution: monoclinic, C2/c, a = 17.555(4) Å, b = 15.277(3) Å, c = 13.093(3) Å, β = 111.179(3)°, V = 3274.0(12) Å3, Z = 4. By contrast, similar reactions in the presence of methanol yielded complexes with the composition [μ-C3N3(OMe)(py)2(pyH)][ReX(CO)3]2 (5, X = Cl; 6, X = Br). Crystal data for 5: monoclinic, C2/c, a = 26.952(2) Å, b = 16.602(1) Å, c = 14.641(1) Å, β = 116.147(1)°, V = 5880.5(8) Å3, Z = 8. 6: monoclinic, C2/c, a = 27.513(3) Å, b = 16.740(2) Å, c = 14.837(2) Å, β = 116.925(2)°, V = 6092.8(10) Å3, Z = 8. An unusual metal-induced methoxylation at the carbon atom of the triazine ring of the bridging TPT ligand was observed. The nucleophilic attack of MeO− on C(3) results in a tetrahedral geometry around the carbon atom. Concomitantly, the uncoordinated pyridyl ring is protonated and rotated into a perpendicular orientation relative to the central C3N3 ring. Reaction of TPT with [NEt4]2[ReBr3-(CO)3] in

  4. Rhenium and technetium complexes that bind to amyloid-β plaques.

    PubMed

    Hayne, David J; North, Andrea J; Fodero-Tavoletti, Michelle; White, Jonathan M; Hung, Lin W; Rigopoulos, Angela; McLean, Catriona A; Adlard, Paul A; Ackermann, Uwe; Tochon-Danguy, Henri; Villemagne, Victor L; Barnham, Kevin J; Donnelly, Paul S

    2015-03-21

    Alzheimer's disease is associated with the presence of insoluble protein deposits in the brain called amyloid plaques. The major constituent of these deposits is aggregated amyloid-β peptide. Technetium-99m complexes that bind to amyloid-β plaques could provide important diagnostic information on amyloid-β plaque burden using Single Photon Emission Computed Tomography (SPECT). Tridentate ligands with a stilbene functional group were used to form complexes with the fac-[M(I)(CO)3](+) (M = Re or (99m)Tc) core. The rhenium carbonyl complexes with tridentate co-ligands that included a stilbene functional group and a dimethylamino substituent bound to amyloid-β present in human frontal cortex brain tissue from subjects with Alzheimer's disease. This chemistry was extended to make the analogous [(99m)Tc(I)(CO)3](+) complexes and the complexes were sufficiently stable in human serum. Whilst the lipophilicity (log D7.4) of the technetium complexes appeared ideally suited for penetration of the blood-brain barrier, preliminary biodistribution studies in an AD mouse model (APP/PS1) revealed relatively low brain uptake (0.24% ID g(-1) at 2 min post injection).

  5. Coordination of cyclo-octasulfur and cyclo-heptaselenium to dinuclear rhenium(I) systems.

    PubMed

    Bacchi, Alessia; Baratta, Walter; Calderazzo, Fausto; Marchetti, Fabio; Pelizzi, Giancarlo

    2002-07-29

    By substitution reactions of the coordinated THF ligands of Re(2)(mu-X)(2)(CO)(6)(THF)(2) by elemental chalcogens (S(8) and red selenium), the complexes Re(2)(mu-X)(2)(CO)(6)(S(8)) (X = Br, 1; I, 2), and Re(2)(mu-X)(2)(CO)(6)(Se(7)), (X = I, 3; Br, 4) have been prepared. Binuclear compound 3 was crystallographically established to be a coordination compound of cyclo-heptaselenium, two adjacent selenium atoms of the Se(7) ligand [Se-Se distance, 2.558(3) A] being bonded to rhenium(I), at an average Re-Se distance of 2.586(3) A, and the nonbonding Re.Re distance being 4.077(3) A. Spectroscopic evidence of the existence of these chalcogen complexes in solution is reported. The Re(2)(mu-X)(2)(CO)(6)(S(8)) complexes undergo S(8) displacement by THF, while the coordinated Se(7) moiety is less readily displaced from 3.

  6. SPS Fabrication of Tungsten-Rhenium Alloys in Support of NTR Fuels Development

    SciTech Connect

    Jonathan A. Webb; Indrajit Charit; Cory Sparks; Darryl P. Butt; Megan Frary; Mark Carroll

    2011-02-01

    Abstract. Tungsten metal slugs were fabricated via Spark Plasma Sintering (SPS) of powdered metals at temperatures ranging from 1575 K to 1975 K and hold times of 5 minutes to 30 minutes, using powders with an average diameter of 7.8 ?m. Sintered tungsten specimens were found to have relative densities ranging from 83 % to 94 % of the theoretical density for tungsten. Consolidated specimens were also tested for their Vickers Hardness Number (VHN), which was fitted as a function of relative density; the fully consolidated VHN was extrapolated to be 381.45 kg/mm2. Concurrently, tungsten and rhenium powders with average respective diameters of 0.5 ?m and 13.3 ?m were pre-processed either by High-Energy-Ball-Milling (HEBM) or by homogeneous mixing to yield W-25at.%Re mixtures. The powder batches were sintered at temperatures of 1975 K and 2175 K for hold times ranging from 0 minutes to 60 minutes yielding relative densities ranging from 94% to 97%. The combination of HEBM and sintering showed a significant decrease in the inter-metallic phases compared to that of the homogenous mixing and sintering.

  7. Evaluation of thrombocytopenia in patients treated with rhenium-186-HEDP: Guidelines for individual dosage recommendations

    SciTech Connect

    Klerk, J.M.H. de; Schip, A.D. van het; Zonnenberg, B.A

    1994-09-01

    A potential limitation of rhenium-186-1,1-hydroxyethylidene diphosphonate ({sup 186}Re-HEDP) therapy in patients with painful bone metastases is thrombocytopenia. Given the palliative character of this therapy, it is essential to be able to predict the degree of thrombocytopenia before therapy. Thus far, 39 prostatic cancer patients with multiple painful bone metastases were treated. Twenty-one patients underwent the therapy twice, resulting in 60 therapies. From the pre-therapy {sup 99m}Tc-HDP scintigram, the bone scan index (BSI) was determined as an index of the extent of bone involvement. The administered activity ranged from 1104 to 3479 MBq {sup 186}Re-HEDP. The platelet count was lowest 4 wk following therapy. From this value and the pretreatment level, the percentage decrease in the platelet count was determined (47%{+-}19%, range 14%-89%). The BSI ranged from 8 to 93. Regression analysis showed a functional relation (R = 0.78; p < 0.001) of the percentage of platelet decrease with BSI and administered activity normalized to standard body surface area. Using this relation, it is possible to predict thrombocytopenia by pretreatment bone scintigraphy and to adjust the dosage to each patient to avoid unacceptable toxicity. 27 refs., 4 figs., 1 tab.

  8. Bone marrow adsorbed dose of rhenium-186-HEDP and the relationship with decreased platelet counts

    SciTech Connect

    Klerk, J.M.H. de; Dieren, E.B. van; Schip, A.D. van het

    1996-01-01

    Rhenium-186(Sn)-1,1-hydroxyethylidene diphosphonate ({sup 186}Re-HEDP) has been used for palliation of metastatic bone pain. The purpose of this study was to find a relationship between the bone marrow absorbed dose and the toxicity, expressed as the percentage decrease in the peripheral blood platelet count. The bone marrow absorbed dose was calculated according to the MIRD model using data obtained from ten treatments of patients suffering from metastatic prostate cancer; noninvasive and pharmacokinetic method were used. The bone marrow doses were related to toxicity using the pharmacodynamic sigmoid E{sub max} model. The mean bone marrow absorbed doses using the noninvasive and pharmacokinetic methods were in a close range to each other (1.07 mGy/MBq and 1.02 mGy/MBq, respectively). There was a good relationship between the toxicity and the bone marrow absorbed dose (r = 0.80). Furthermore, the EDrm{sub 50} (i.e., the bone marrow absorbed dose producing a 50% platelet decrease) to bone marrow for {sup 186}Re-HEDP was on the order of 2 Gy. Although the function of normal bone marrow is affected by metastases in patients with metastatic bone disease, the MIRD model can be used to relate toxicity to the bone marrow absorbed dose after a therapeutic dosage of {sup 186}Re-HEDP. 33 refs., 1 fig., 1 tab.

  9. Lipid Nanocapsules Loaded with Rhenium-188 Reduce Tumor Progression in a Rat Hepatocellular Carcinoma Model

    PubMed Central

    Vanpouille-Box, Claire; Lacoeuille, Franck; Roux, Jérôme; Aubé, Christophe; Garcion, Emmanuel; Lepareur, Nicolas; Oberti, Frédéric; Bouchet, Francis; Noiret, Nicolas; Garin, Etienne; Benoît, Jean-Pierre; Couturier, Olivier; Hindré, François

    2011-01-01

    Background Due to their nanometric scale (50 nm) along with their biomimetic properties, lipid nanocapsules loaded with Rhenium-188 (LNC188Re-SSS) constitute a promising radiopharmaceutical carrier for hepatocellular carcinoma treatment as its size may improve tumor penetration in comparison with microspheres devices. This study was conducted to confirm the feasibility and to assess the efficacy of internal radiation with LNC188Re-SSS in a chemically induced hepatocellular carcinoma rat model. Methodology/Principal Findings Animals were treated with an injection of LNC188Re-SSS (80 MBq or 120 MBq). The treated animals (80 MBq, n = 12; 120 MBq, n = 11) were compared with sham (n = 12), blank LNC (n = 7) and 188Re-perrhenate (n = 4) animals. The evaluation criteria included rat survival, tumor volume assessment, and vascular endothelial growth factor quantification. Following treatment with LNC188Re-SSS (80 MBq) therapeutic efficiency was demonstrated by an increase in the median survival from 54 to 107% compared with control groups with up to 7 long-term survivors in the LNC188Re-SSS group. Decreased vascular endothelial growth factor expression in the treated rats could indicate alterations in the angiogenesis process. Conclusions/Significance Overall, these results demonstrate that internal radiation with LNC188Re-SSS is a promising new strategy for hepatocellular carcinoma treatment. PMID:21408224

  10. Very high-efficiency organic light-emitting diodes based on cyclometallated rhenium (I) complex

    NASA Astrophysics Data System (ADS)

    Li, Xiao; Zhang, Dongyu; Li, Wenlian; Chu, Bei; Han, Liangliang; Zhu, Jianzhuo; Su, Zisheng; Bi, Defeng; Wang, Dan; Yang, Dongfang; Chen, Yiren

    2008-02-01

    A phosphorescent (Ph) cyclometallated rhenium (I) (ReI) complex was synthesized by reacting 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline with pentacarbonylbromorhenium in refluxing toluene solutions. The precipitates were easily sublimed to obtain a pure electrically neutral carbonyl diamine ReI complex, (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline)Re(CO)3Br. The Re complex was used as an orange emitting dopant in 4,4'-N,N'-dicarbazole-biphenyl host to fabricate Ph organic light-emitting diodes (PhOLEDs). The maximum electroluminescence (EL) efficiency and luminance of 21.8cd/A and 8315cd/cm2 were harvested, respectively, which were the highest EL results among the PhOLEDs based on ReI complexes. The improvements of the EL performances could be ascribed to the synergistic effects of together incorporation of two reciprocally repulsive phenyl and methyl groups on the backbone of 1,10-phenanthroline molecule of the ligand.

  11. Pressure induced enhancement of the magnetic ordering temperature in rhenium(IV) monomers

    PubMed Central

    Woodall, Christopher H.; Craig, Gavin A.; Prescimone, Alessandro; Misek, Martin; Cano, Joan; Faus, Juan; Probert, Michael R.; Parsons, Simon; Moggach, Stephen; Martínez-Lillo, José; Murrie, Mark; Kamenev, Konstantin V.; Brechin, Euan K.

    2016-01-01

    Materials that demonstrate long-range magnetic order are synonymous with information storage and the electronics industry, with the phenomenon commonly associated with metals, metal alloys or metal oxides and sulfides. A lesser known family of magnetically ordered complexes are the monometallic compounds of highly anisotropic d-block transition metals; the ‘transformation' from isolated zero-dimensional molecule to ordered, spin-canted, three-dimensional lattice being the result of through-space interactions arising from the combination of large magnetic anisotropy and spin-delocalization from metal to ligand which induces important intermolecular contacts. Here we report the effect of pressure on two such mononuclear rhenium(IV) compounds that exhibit long-range magnetic order under ambient conditions via a spin canting mechanism, with Tc controlled by the strength of the intermolecular interactions. As these are determined by intermolecular distance, ‘squeezing' the molecules closer together generates remarkable enhancements in ordering temperatures, with a linear dependence of Tc with pressure. PMID:28000676

  12. Synthesis, characterization, and biological studies of emissive rhenium-glutamine conjugates.

    PubMed

    Huang, Rachel; Langille, Graeme; Gill, Ravanjir K; Li, Cindy Mei Jin; Mikata, Yuji; Wong, May Q; Yapp, Donald T; Storr, Tim

    2013-10-01

    Two new rhenium complexes containing pyridine-triazole (pyta) and quinoline-triazole (quinta) ligands with attached glutamine-targeting agents have been characterized and tested for uptake in the HT-29 human colon adenocarcinoma cell line. The glutamine moiety in Re(CO)3Br(pyta) (1) and Re(CO)3Br(quinta) (2) remains pendant in solution. Both complexes exhibit absorptions in the 300-400-nm range with metal-to-ligand charge transfer (MLCT) character, as predicted by time-dependent density functional theory calculations. Geometrical analysis by theoretical calculations provides information on the cationic complexes 1 (+) and 2 (+) resulting from aquo for halide ligand exchange under aqueous conditions. The emissive properties of both complexes were studied under aqueous conditions, and the measured quantum yields were 0.46 % for 1 (+) and 0.18 % for 2 (+). The large Stokes shifts and oxygen sensitivity of the emission suggest a (3)MLCT process for both complexes. Cell studies in the HT-29 cell line demonstrate that both complexes are nontoxic over a large concentration range (0-1.4 mM). Preliminary uptake studies show that 2 (+), but not 1 (+), displays significant concentration-dependent uptake at 3 and 24 h.

  13. Laser desorption ionization of small molecules assisted by tungsten oxide and rhenium oxide particles.

    PubMed

    Bernier, Matthew C; Wysocki, Vicki H; Dagan, Shai

    2015-07-01

    Inorganic metal oxides have shown potential as matrices for assisting in laser desorption ionization with advantages over the aromatic acids typically used. Rhenium and tungsten oxides are attractive options due to their high work functions and relative chemical inertness. In this work, it is shown that ReO3 and WO3 , in microparticle (μP) powder forms, can efficiently facilitate ionization of various types of small molecules and provide minimized background contamination at analyte concentrations below 1 ng/µL. This study shows that untreated inorganic WO3 and ReO3 particles are valid matrix options for detection of protonatable, radical, and precharged species under laser desorption ionization. Qualitatively, the WO3 μP showed improved detection of apigenin, sodiated glucose, and precharged analyte choline, while the ReO3 μP allowed better detection of protonated cocaine, quinuclidine, ametryn, and radical ions of polyaromatic hydrocarbons at detection levels as low as 50 pg/µL. For thermometer ion survival yield experiments, it was also shown that the ReO3 powder was significantly softer than α-cyano-4-hydroxycinnaminic acid. Furthermore, it provided higher intensities of cocaine and polyaromatic hydrocarbons, at laser flux values equal to those used with α-cyano-4-hydroxycinnaminic acid.

  14. The synthesis and toxicity of tripodal tricarbonyl rhenium complexes as radiopharmaceutical models

    PubMed Central

    Robenstine, Sarah; Barone, Natalie V.; Underwood, Adam C.; Milsted, Amy; Franklin, Brenton R.; Herrick, Richard S.; Ziegler, Christopher J.

    2012-01-01

    We report the synthesis and toxicity of a series of rhenium(I) tricarbonyl complexes incorporating the trisaminomethylethane (TAME) ligand. Compounds with the (TAME)Re(CO)3+ cation were synthesized via several routes, including by use of Re(CO)5X precursors as well as the aqueous cation Re(CO)3(H2O)3+. Salts of the formula [(TAME)Re(CO)3]X where X = Br−, Cl−, NO3−, PF6− and ClO4− were evaluated using two cell lines: the monoclonal S3 HeLa line and a vascular smooth muscle cell line harvested from mice. All compounds have isostructural cations and differ only in the identity of the non-coordinating anion. None of the complexes exhibited any appreciable toxicity in the HeLa line up to the solubility limit. In the vascular smooth muscle cell line, the bromide salt exhibited some cytotoxicity, but this observation most likely results from the presence of bromide anion, which has been shown to have limited toxicity. PMID:20362340

  15. Prospects of molybdenum and rhenium octahedral cluster complexes as X-ray contrast agents.

    PubMed

    Krasilnikova, Anna A; Shestopalov, Michael A; Brylev, Konstantin A; Kirilova, Irina A; Khripko, Olga P; Zubareva, Kristina E; Khripko, Yuri I; Podorognaya, Valentina T; Shestopalova, Lidiya V; Fedorov, Vladimir E; Mironov, Yuri V

    2015-03-01

    Investigation of new X-ray contrast media for radiography is an important field of science since discovering of X-rays in 1895. Despite the wide diversity of available X-ray contrast media the toxicity, especially nephrotoxicity, is still a big problem to be solved. The octahedral metal-cluster complexes of the general formula [{M6Q8}L6] can be considered as quite promising candidates for the role of new radiocontrast media due to the high local concentration of heavy elements, high tuning ability of ligand environment and low toxicity. To exemplify this, the X-ray computed tomography experiments for the first time were carried out on some octahedral cluster complexes of molybdenum and rhenium. Based on the obtained data it was proposed to investigate the toxicological proprieties of cluster complex Na2H8[{Re6Se8}(P(CH2CH2CONH2)(CH2CH2COO)2)6]. Observed low cytotoxic and acute toxic effects along with rapid renal excretion of the cluster complex evidence its perspective as an X-ray contrast media for radiography. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Approaching the Minimum Thermal Conductivity in Rhenium-Substituted Higher Manganese Silicides

    SciTech Connect

    Chen, Xi; Girard, S. N.; Meng, F.; Lara-Curzio, Edgar; Jin, S; Goodenough, J. B.; Zhou, J. S.; Shi, L

    2014-01-01

    Higher manganese silicides (HMS) made of earth-abundant and non-toxic elements are regarded as promising p-type thermoelectric materials because their complex crystal structure results in low lattice thermal conductivity. It is shown here that the already low thermal conductivity of HMS can be reduced further to approach the minimum thermal conductivity via partial substitu- tion of Mn with heavier rhenium (Re) to increase point defect scattering. The solubility limit of Re in the obtained RexMn1 xSi1.8 is determined to be about x = 0.18. Elemental inhomogeneity and the formation of ReSi1.75 inclusions with 50 200 nm size are found within the HMS matrix. It is found that the power factor does not change markedly at low Re content of x 0.04 before it drops considerably at higher Re contents. Compared to pure HMS, the reduced lattice thermal conductivity in RexMn1 xSi1.8 results in a 25% increase of the peak figure of merit ZT to reach 0.57 0.08 at 800 K for x = 0.04. The suppressed thermal conductivity in the pure RexMn1 xSi1.8 can enable further investigations of the ZT limit of this system by exploring different impurity doping strategies to optimize the carrier concentration and power factor.

  17. The "catalytic nitrosyl effect": NO bending boosting the efficiency of rhenium based alkene hydrogenations.

    PubMed

    Jiang, Yanfeng; Schirmer, Birgitta; Blacque, Olivier; Fox, Thomas; Grimme, Stefan; Berke, Heinz

    2013-03-13

    Diiodo Re(I) complexes [ReI2(NO)(PR3)2(L)] (3, L = H2O; 4 , L = H2; R = iPr a, Cy b) were prepared and found to exhibit in the presence of "hydrosilane/B(C6F5)3" co-catalytic systems excellent activities and longevities in the hydrogenation of terminal and internal alkenes. Comprehensive mechanistic studies showed an inverse kinetic isotope effect, fast H2/D2 scrambling and slow alkene isomerizations pointing to an Osborn type hydrogenation cycle with rate determining reductive elimination of the alkane. In the catalysts' activation stage phosphonium borates [R3PH][HB(C6F5)3] (6, R = iPr a, Cy b) are formed. VT (29)Si- and (15)N NMR experiments, and dispersion corrected DFT calculations verified the following facts: (1) Coordination of the silylium cation to the ONO atom facilitates nitrosyl bending; (2) The bent nitrosyl promotes the heterolytic cleavage of the H-H bond and protonation of a phosphine ligand; (3) H2 adds in a bifunctional manner across the Re-N bond. Nitrosyl bending and phosphine loss help to create two vacant sites, thus triggering the high hydrogenation activities of the formed "superelectrophilic" rhenium centers.

  18. {sup 188}Rhenium-HEDP in the Treatment of Pain in Bone Metastases

    SciTech Connect

    Gaudiano, J.; Savio, E.; Robles, A.; Muniz, S.; Leon, A.; Verdera, S.; Martinez, G.; Hermida, J.C.; Knapp, F.F., Jr.

    1999-01-18

    Systemic use of radiopharmaceuticals is a recognized alternative method for the treatment of pain in patients with multiple bone metastasis. A new option, {sup 188}Re-HEDP is proposed, using generator-obtained {sup 188}Rhenium ({beta} energy = 2.1 MeV, {gamma} energy = 155 keV, half-life = 16.9 hours). After establishing parameters of biodistribution, dosimetry and image acquisition in mice, rats and rabbits, Phase I and II studies were conducted on 12 patients with multiple metastasis from carcinomas, with pain surpassing other analgesic options. More than 50% pain relief was found in 91% of the patients, with total relief during a variable period in 41% of them allowing opiate and other analgesic drugs to be decreased or withdrawn, and showing a lower bone marrow contribution to total absorbed dose than that reported for other similar radiopharmaceuticals. Further study of this option is recommended in order to determine higher dose protocols without toxic bone marrow reaction possibilities.

  19. Detection of a meteoritic component in ivory coast tektites with rhenium-osmium isotopes.

    PubMed

    Koeberl, C; Shirey, S B

    1993-07-30

    Measurement of rhenium (Re) and osmium (Os) concentrations and Os isotopic compositions in Ivory Coast tektites (natural glasses with upper crustal compositions that are ejected great distances during meteorite impact) and rocks from the inferred source crater, Lake Bosumtwi, Ghana, show that these tektites incorporate about 0.6 percent of a meteoritic component. Analysis of elemental abundances of noble metals alone gives equivocal results in the detection of meteoritic components because the target rocks already have relatively large amounts of noble metals. The Re-Os system is ideally suited for the study of meteorite impacts on old continental crust for three reasons. (i) The isotopic compositions of the target rocks and the meteoritic impactor are significantly different. (ii) Closed-system mixing of target rocks and meteorites is linear on Re-Os isochron diagrams, which thus permits identification of the loss of Re or Os. (iii) Osmium isotopic compositions are not likely to be altered during meteorite impact even if Re and Os are lost.

  20. Detection of a meteoritic component in Ivory Coast tektites with rhenium-osmium isotopes

    NASA Astrophysics Data System (ADS)

    Koeberl, Christian; Shirey, Steven B.

    1993-07-01

    Measurement of rhenium (Re) and osmium (Os) concentrations and Os isotopic compositions in Ivory Coast tektites (natural glasses with upper crustal compositions that are ejected great distances during meteorite impact) and rocks from the inferred source crater, Lake Bosumtwi, Ghana, show that these tektites incorporate about 0.6 percent of a meteoritic component. Analysis of elemental abundances of noble metals alone gives equivocal results in the detection of meteoritic components because the target rocks already have relatively large amounts of noble metals. The Re-Os system is ideally suited for the study of meteorite impacts on old continental crust for three reasons. The isotopic compositions of the target rocks and the meteoritic impactor are significantly different. Closed-system mixing of target rocks and meteorites is linear on Re-Os isochron diagrams, which thus permits identification of the loss of Re or Os. Osmium isotopic compositions are not likely to be altered during meteorite impact even if Re and Os are lost.

  1. Layer-by-Layer Sorting of Rhenium Disulfide via High-Density Isopycnic Density Gradient Ultracentrifugation.

    PubMed

    Kang, Joohoon; Sangwan, Vinod K; Wood, Joshua D; Liu, Xiaolong; Balla, Itamar; Lam, David; Hersam, Mark C

    2016-11-09

    Isopycnic density gradient ultracentrifugation (iDGU) has been widely applied to sort nanomaterials by their physical and electronic structure. However, the commonly used density-gradient medium iodixanol has a finite maximum buoyant density that prevents the use of iDGU for high-density nanomaterials. Here, we overcome this limit by adding cesium chloride (CsCl) to iodixanol, thus increasing its maximum buoyant density to the point where the high-density two-dimensional nanomaterial rhenium disulfide (ReS2) can be sorted in a layer-by-layer manner with iDGU. The resulting aqueous ReS2 dispersions show photoluminescence at ∼1.5 eV, which is consistent with its direct bandgap semiconductor electronic structure. Furthermore, photocurrent measurements on thin films formed from solution-processed ReS2 show a spectral response that is consistent with optical absorbance and photoluminescence data. In addition to providing a pathway for effective solution processing of ReS2, this work establishes a general methodology for sorting high-density nanomaterials via iDGU.

  2. Ligand-bridged rhenium(I) complexes: An electrochemical and photophysical study

    SciTech Connect

    Yoblinski, B.J.; Stathis, M.; Guarr, T.F. )

    1992-01-08

    The synthesis and properties of a series of rhenium(I) carbonyls incorporating the bidentate bridging ligands 4{prime},7{prime}-phenanthrolino-5{prime},6{prime}:5,6-pyrazine (ppz), 2,3-bis(2-pyridyl)pyrazine (bppz), and 6,7-dimethyl-2,3-bis(2-pyridyl)quinoxaline (ddpq) have been investigated. All mononuclear complexes are emissive in room-temperature fluid solution; the luminescence originates from an MLCT excited state. On the other hand, emission was detected for only one of the binuclear complexes, ((ppz)(Re-(CO){sub 3}(CH{sub 3}CN)){sub 2}){sup 2+}. The lack of emission from the remaining binuclear species is attributed to the perturbation of the {pi}* orbital on the bridging ligand that results from the attachment of the second metal center. The magnitude of this effect has been probed by electrochemical and spectroscopic experiments. Lifetime measurements confirm the existence of a correlation between MLCT energy and the nonradiative decay rate, and the observed trend is in at least qualitative agreement with the energy gap law. Variations in the quantum yield for emission between similar complexes possessing different bridging ligands are attributed to changes in ligand rigidity, and complexes of ppz exhibit the largest {phi}{sub em} values. Not only are the corresponding bppz and ddpq derivatives much weaker emitters, but steric interactions lead to the thermal decomposition of binuclear complexes based on these ligands.

  3. Trace element profiles in sediments as proxies of dead zone history; rhenium compared to molybdenum.

    PubMed

    Helz, George R; Adelson, Jordan M

    2013-02-05

    Warm-season dead zones-volumes of coastal water containing too little O(2) to support macrofauna-are a growing global menace. Trace elements that are deposited in sediments in response to reducing or sulfidic conditions can provide proxy records for reconstructing dead zone evolution. Based on relative enrichment in reduced vs oxidized marine sediments, Re seems promising as a dead zone proxy. Here, Re is determined by isotope dilution mass spectrometry in sediments underlying the summertime dead zone in Chesapeake Bay. Contrary to expectation, Re becomes only modestly (∼2-fold) elevated during the 20th century and fails to track the historic record of summertime O(2) depletion. Rhenium enrichments are watershed-specific and apparently controlled by anthropogenic sources, not by redox-linked authigenic processes. In contrast, Mo enrichments do track historic O(2) depletion. Three factors cause redox control to override anthropogenic control in the case of Mo: relative to weathering fluxes, anthropogenic Mo fluxes are weaker than Re fluxes; during anoxic periods, Mn refluxing amplifies Mo but not Re concentrations near the sediment surface; and high pore water sulfide-polysulfide promotes Mo fixation in pyrite while promoting formation of organo-Re adducts; the latter are too mobile and reactive to preserve a reliable historic record under seasonally fluctuating redox conditions.

  4. Phosphorene/rhenium disulfide heterojunction-based negative differential resistance device for multi-valued logic

    PubMed Central

    Shim, Jaewoo; Oh, Seyong; Kang, Dong-Ho; Jo, Seo-Hyeon; Ali, Muhammad Hasnain; Choi, Woo-Young; Heo, Keun; Jeon, Jaeho; Lee, Sungjoo; Kim, Minwoo; Song, Young Jae; Park, Jin-Hong

    2016-01-01

    Recently, negative differential resistance devices have attracted considerable attention due to their folded current–voltage characteristic, which presents multiple threshold voltage values. Because of this remarkable property, studies associated with the negative differential resistance devices have been explored for realizing multi-valued logic applications. Here we demonstrate a negative differential resistance device based on a phosphorene/rhenium disulfide (BP/ReS2) heterojunction that is formed by type-III broken-gap band alignment, showing high peak-to-valley current ratio values of 4.2 and 6.9 at room temperature and 180 K, respectively. Also, the carrier transport mechanism of the BP/ReS2 negative differential resistance device is investigated in detail by analysing the tunnelling and diffusion currents at various temperatures with the proposed analytic negative differential resistance device model. Finally, we demonstrate a ternary inverter as a multi-valued logic application. This study of a two-dimensional material heterojunction is a step forward toward future multi-valued logic device research. PMID:27819264

  5. Study on the formation of rhenium borides by density functional calculations

    NASA Astrophysics Data System (ADS)

    Agundez, R. R.; Soto, G.; Moreno, M. G.; Reyes-Serrato, A.

    2009-03-01

    The searching of hard and superhard materials is a hot topic in material science. Two known factors are fundamental to get high hardness: (1) high valence-electron density; and (2) high number of electron in covalent bonds. The 5d-transition metals comply with requirement (1); so, the task is to fulfill condition (2) without expanding its native structure. Supposedly this is possible by developing interstitial alloys with elements of moderate electronegativity, like boron and/or carbon. This idea materializes in the very hard ReB2, which scratches the surface of diamond. This work is a study in the formation of rhenium borides by density functional calculations. Here, we want to reveal the changes that would occur in the hexagonal close packed lattice of Re as B is inserted into its interstitial sites. We cover compositions in ReBx from x = 0 to x = 3 in x steps of 0.125. B is positioned in octahedral and tetrahedral interstices of Re, and for each arrangements we have calculated cell volume, cohesive energy, bulk modulus, valence electron concentration, and energy density. Supported by FONDOS CONACYT I0013, SNI-ESTUDIANTES 2008-01, SOLICITUD: 103909

  6. 188Rhenium-induced cell death and apoptosis in a panel of tumor cell lines

    NASA Astrophysics Data System (ADS)

    Antoccia, Antonio; Banzato, Alessandra; Bello, Michele; Bollini, Dante; De Notaristefani, Francesco; Giron, Cecilia; Mazzi, Ulderico; Alafort, Laura Melendez; Moschini, Giuliano; Nadali, Anna; Navarria, Francesco; Perrotta, Andrea; Rosato, Antonio; Tanzarella, Caterina; Uzunov, Nikolay

    2007-02-01

    Assessment of "in vitro" tumor growth inhibition and radiobiological effects, such as apoptosis, have been evaluated in human neoplastic cells of different histotypes (H460 lung cancer cells, U87 glioblastoma, LnCaP prostate tumor cells) treated using solutions of 188Rhenium-perrhenate. The MTT assay, which measures mitochondrial metabolism in the entire cell culture is a recognized test for cytotoxicity and was used in cells exposed 48-72 h to specific activities ranged from 37 to 148 GBq/l. Whereas H460 and LnCaP were particularly sensitive to treatment, U87 glioblastoma cells behaved as radioresistant ones. However, evaluation of 188Re-induced apoptosis indicated that this kind of cell death contributed only marginally to the reduction in cell viability of H460 and LNCaP lines, suggesting the existence of protective mechanisms against apoptosis. In this respect, the membrane receptor, CD44, whose expression is dysregulated in most malignant cell types has proven to alter the response of cancer cells to apoptotic stimuli, including ionizing radiation. Cell samples decorated with a FITC-labelled CD44 antibody indicated, that in H460 and U87 cells the CD44(+) correlated well with an apoptosis-resistant response. Conversely, LnCap cells proven as CD44(-) did not display however sensitivity to radio-induced apoptosis.

  7. Laser Desorption Ionization of small molecules assisted by Tungsten oxide and Rhenium oxide particles

    PubMed Central

    Bernier, Matthew; Wysocki, Vicki; Dagan, Shai

    2015-01-01

    Inorganic metal oxides have shown potential as matrices for assisting in laser desorption ionization (LDI) with advantages over the aromatic acids typically used. Rhenium and tungsten oxides are an attractive option due to their high work functions and relative chemical inertness. In this work, it is shown that ReO3 and WO3, in microparticle (μP) powder forms, can efficiently ionize various types of small molecules and provide minimized background contamination at analyte concentrations below 1 ng/μL. This study shows that untreated inorganic WO3 and ReO3 particles are valid matrix options for detection of protonatable, radical, and precharged species under LDI. Qualitatively, the WO3 μP showed an improved detection of apigenin, sodiated glucose, and the precharged analyte choline, while the ReO3 μP allowed detection of protonated cocaine, quinuclidine, ametryn, and radical ions of polyaromatic hydrocarbons at detection levels as low as 50 pg/μL. For thermometer ion survival yield experiments, it was also shown that the ReO3 powder was significantly softer than CCA. Furthermore, it provided higher intensities of cocaine and polyaromatic hydrocarbons, at laser flux values equal to that used with CCA. PMID:26349643

  8. Phosphorene/rhenium disulfide heterojunction-based negative differential resistance device for multi-valued logic

    NASA Astrophysics Data System (ADS)

    Shim, Jaewoo; Oh, Seyong; Kang, Dong-Ho; Jo, Seo-Hyeon; Ali, Muhammad Hasnain; Choi, Woo-Young; Heo, Keun; Jeon, Jaeho; Lee, Sungjoo; Kim, Minwoo; Song, Young Jae; Park, Jin-Hong

    2016-11-01

    Recently, negative differential resistance devices have attracted considerable attention due to their folded current-voltage characteristic, which presents multiple threshold voltage values. Because of this remarkable property, studies associated with the negative differential resistance devices have been explored for realizing multi-valued logic applications. Here we demonstrate a negative differential resistance device based on a phosphorene/rhenium disulfide (BP/ReS2) heterojunction that is formed by type-III broken-gap band alignment, showing high peak-to-valley current ratio values of 4.2 and 6.9 at room temperature and 180 K, respectively. Also, the carrier transport mechanism of the BP/ReS2 negative differential resistance device is investigated in detail by analysing the tunnelling and diffusion currents at various temperatures with the proposed analytic negative differential resistance device model. Finally, we demonstrate a ternary inverter as a multi-valued logic application. This study of a two-dimensional material heterojunction is a step forward toward future multi-valued logic device research.

  9. Synthesis and in vitro evaluation of a rhenium-cyclized somatostatin derivative series.

    PubMed

    Bigott-Hennkens, Heather M; Junnotula, Sulochana; Ma, Lixin; Gallazzi, Fabio; Lewis, Michael R; Jurisson, Silvia S

    2008-03-13

    The structure-activity relationships of a series of rhenium (Re)-cyclized octreotide derivatives are described. The effects of changes in the peptide sequence, N-terminus, and C-terminus on metal cyclization, as well as binding to the somatostatin receptor, were investigated. Each peptide complex was found to have an integrated Re(V) core with a single metal oxo group, two coordination sites filled by the cysteine sulfhydryls, and another by the amide nitrogen of Phe (3)/Tyr (3). The final coordination site was determined by the peptide N-terminus: the N-terminal amine coordinated for N-NH 2 peptides and the amide nitrogen of Thr (6) for peptides with acetylated N-termini. Re-cyclization of the octreotide derivatives led to structural perturbations of the somatostatin receptor-binding sequence relative to the Re-free disulfide analogues, resulting in reduced binding affinities. The findings presented herein demonstrate the importance of understanding the consequences of structural modifications when designing metal-peptide complexes for somatostatin receptor targeting.

  10. Phosphorene/rhenium disulfide heterojunction-based negative differential resistance device for multi-valued logic.

    PubMed

    Shim, Jaewoo; Oh, Seyong; Kang, Dong-Ho; Jo, Seo-Hyeon; Ali, Muhammad Hasnain; Choi, Woo-Young; Heo, Keun; Jeon, Jaeho; Lee, Sungjoo; Kim, Minwoo; Song, Young Jae; Park, Jin-Hong

    2016-11-07

    Recently, negative differential resistance devices have attracted considerable attention due to their folded current-voltage characteristic, which presents multiple threshold voltage values. Because of this remarkable property, studies associated with the negative differential resistance devices have been explored for realizing multi-valued logic applications. Here we demonstrate a negative differential resistance device based on a phosphorene/rhenium disulfide (BP/ReS2) heterojunction that is formed by type-III broken-gap band alignment, showing high peak-to-valley current ratio values of 4.2 and 6.9 at room temperature and 180 K, respectively. Also, the carrier transport mechanism of the BP/ReS2 negative differential resistance device is investigated in detail by analysing the tunnelling and diffusion currents at various temperatures with the proposed analytic negative differential resistance device model. Finally, we demonstrate a ternary inverter as a multi-valued logic application. This study of a two-dimensional material heterojunction is a step forward toward future multi-valued logic device research.

  11. Protic conversion of nitrile into azavinylidene complexes of rhenium, a mechanistic theoretical study.

    PubMed

    Kuznetsov, Maxim L; Nazarov, Alexey A; Pombeiro, Armando J L

    2005-09-15

    The mechanism of the protonation of the rhenium nitrile chloro-complexes [ReCl(NCCH3)(PH3)4] (2), taken as models of the real systems [ReCl(NCR)(dppe)(2)] (dppe = Ph2PCH2CH2PPh2), leading to the azavinylidene products [ReCl(NC(H)CH3)(PH3)4]+ (3) was investigated by theoretical methods at the B3LYP level of theory. Electrostatic and molecular orbital arguments and thermodynamic, kinetic, and steric factors are analyzed and indicate that the chlorine atom is the most probable site of the initial proton attack, although the direct protonation of the nitrile carbon atom is also possible as a concurrent process. For the cis-isomer of 2, the initially formed chloro-protonated species cis-[Re(ClH)(NCCH3)(PH3)4]+ further converts to the azavinylidene cis-3 via either an acid-independent 1,4-proton shift or an acid-base catalyzed pathway involving a second protonation of the nitrile carbon atom to give cis-[Re(ClH)(NC(H)CH3)(PH3)4]2+ followed by elimination of the proton from the chlorine atom.

  12. Tautomerization of 2-nitroso-N-arylanilines by coordination as N,N'-chelate ligands to rhenium(I) complexes and the anticancer activity of newly synthesized oximine rhenium(I) complexes against human melanoma and leukemia cells in vitro.

    PubMed

    Wirth, Stefan; Wallek, Andreas U; Zernickel, Anna; Feil, Florian; Sztiller-Sikorska, M; Lesiak-Mieczkowska, K; Bräuchle, Christoph; Lorenz, Ingo-Peter; Czyz, M

    2010-07-01

    The synthesis, structural characterization and biological activity of eight ortho-quinone(N-aryl)-oximine rhenium(I) complexes are described. The reaction of the halogenido complexes (CO)(5)ReX (X = Cl (4), Br (5)) with 2-nitroso-N-arylanilines {(C(6)H(3)ClNO)NH(C(6)H(4)R)} (R = p-Cl, p-Me, o-Cl, H) (3a-d) in tetrahydrofurane (THF) yields the complexes fac-(CO)(3)XRe{(C(6)H(3)ClNO)NH(C(6)H(4)R)} (6a-d, 7a-d) with the tautomerized ligand acting as a N,N'-chelate. The substitution of two carbonyl ligands leads to the formation of a nearly planar 5-membered metallacycle. During coordination the amino-proton is shifted to the oxygen of the nitroso group which can be observed in solution for 6 and 7 by (1)H NMR spectroscopy and in solid state by crystal structure analysis. After purification, all compounds have been fully characterized by their (1)H and (13)C NMR, IR, UV/visible (UV/Vis) and mass spectra. The X-ray structure analyses revealed a distorted octahedral coordination of the CO, X and N,N'-chelating ligands for all Re(I) complexes. Biological activity of four oximine rhenium(I) complexes was assessed in vitro in two highly aggressive cancer cell lines: human metastatic melanoma A375 and human chronic myelogenous leukemia K562. Chlorido complexes (6a and 6c) were more efficient than bromido compounds (7d and 7b) in inducing apoptotic cell death of both types of cancer cells. Melanoma cells were more susceptible to tested rhenium(I) complexes than leukemia cells. None of the ligands (3a-d) showed any significant anticancer activity. 2010 Elsevier Inc. All rights reserved.

  13. Versatile Coating

    NASA Technical Reports Server (NTRS)

    1990-01-01

    A radome at Logan Airport and a large parabolic antenna at the Wang Building in Massachusetts are protected from weather, corrosion and ultraviolet radiation by a coating, specially designed for antennas and radomes, known as CRC Weathertite 6000. The CRC 6000 line that emerged from Boyd Coatings Research Co., Inc. is a solid dispersion of fluorocarbon polymer and polyurethane that yields a tough, durable film with superior ultraviolet resistance and the ability to repel water and ice over a long term. Additionally, it provides resistance to corrosion, abrasion, chemical attacks and impacts. Material can be used on a variety of substrates, such as fiberglass, wood, plastic and concrete in addition to steel and aluminum. In addition Boyd Coatings sees CRC 6000 applicability as an anti-icing system coated on the leading edge of aircraft wings.

  14. Protective Coating

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Inorganic Coatings, Inc.'s K-Zinc 531 protective coating is water-based non-toxic, non-flammable and has no organic emissions. High ratio silicate formula bonds to steel, and in 30 minutes, creates a very hard ceramic finish with superior adhesion and abrasion resistance. Improved technology allows application over a minimal commercial sandblast, fast drying in high humidity conditions and compatibility with both solvent and water-based topcoats. Coating is easy to apply and provides long term protection with a single application. Zinc rich coating with water-based potassium silicate binder offers cost advantages in materials, labor hours per application, and fewer applications over a given time span.

  15. Fac-Re(bpy)(CO){sub 3}(COOMe): A model metallocarboxylate complex of rhenium with a bipyridyl ligand

    SciTech Connect

    Gibson, D.H.; Sleadd, B.A.; Vij, A.

    1999-05-01

    The title compound fac-(2,2{prime}-bipyridyl)(carbomethoxy)rhenium tricarbonyl, crystallizes in the monoclinic system, space group P2{sub 1}/c with the following crystal data: a = 8.37551(1), b = 6.6934(1), c = 26.2098(1) {angstrom}, V({angstrom}{sup 3}) = 1,535.93(3), Z = 4, and {beta} = 90.0971(2). The metal environment is slightly distorted octahedral with a chelating bipyridyl ligand and a facial arrangement of the carbon monoxide ligands.

  16. Two-Electron Carbon Dioxide Reduction Catalyzed by Rhenium(I) Bis(imino)acenaphthene Carbonyl Complexes

    PubMed Central

    Portenkirchner, Engelbert; Kianfar, Elham; Sariciftci, Niyazi Serdar; Knör, Günther

    2014-01-01

    Rhenium(I) carbonyl complexes carrying substituted bis(arylimino)acenaphthene ligands (BIAN-R) have been tested as potential catalysts for the two-electron reduction of carbon dioxide. Cyclic voltammetric studies as well as controlled potential electrolysis experiments were performed using CO2-saturated solutions of the complexes in acetonitrile and acetonitrile–water mixtures. Faradaic efficiencies of more than 30 % have been determined for the electrocatalytic production of CO. The effects of ligand substitution patterns and water content of the reaction medium on the catalytic performance of the new catalysts are discussed. PMID:24737649

  17. Abundances and isotopic compositions of rhenium and osmium in pyrite samples from the Huaibei coalfield, Anhui, China

    USGS Publications Warehouse

    Liu, Gaisheng; Chou, C.-L.; Peng, Z.; Yang, G.

    2008-01-01

    Two pyrite samples from the Shihezi Formation (Lower Permian), Huaibei coalfield, Anhui, China, have been analyzed for abundances and isotopic compositions of rhenium and osmium using negative thermal ion mass spectrometry. The Re-Os ages of the pyrites are 64.4 and 226 Ma, which are younger than the formation age of the coal seam. The pyrite samples may consist of pyrite formed at various stages during the history of coal formation. The ??Osvalues of the two pyrite samples are +17 and +18, respectively. Such high ??Osvalues are reported for the first time for recycles crustal materials from a sedimentary basin. ?? Springer-Verlag 2007.

  18. Facile rhenium-peptide conjugate synthesis using a one-pot derived Re(CO)3 reagent.

    PubMed

    Chanawanno, Kullapa; Kondeti, Vinay; Caporoso, Joel; Paruchuri, Sailaja; Leeper, Thomas C; Herrick, Richard S; Ziegler, Christopher J

    2016-03-21

    We have synthesized two Re(CO)3-modified lysine complexes (1 and 2), where the metal is attached to the amino acid at the Nε position, via a one-pot Schiff base formation reaction. These compounds can be used in the solid phase synthesis of peptides, and to date we have produced four conjugate systems incorporating neurotensin, bombesin, leutenizing hormone releasing hormone, and a nuclear localization sequence. We observed uptake into human umbilical vascular endothelial cells as well as differential uptake depending on peptide sequence identity, as characterized by fluorescence and rhenium elemental analysis.

  19. Rhenium-catalyzed didehydroxylation of vicinal diols to alkenes using a simple alcohol as a reducing agent.

    PubMed

    Arceo, Elena; Ellman, Jonathan A; Bergman, Robert G

    2010-08-25

    A new method for the catalytic didehydroxylation of vicinal diols is described. Employing a readily available low-valent rhenium carbonyl complex and a simple alcohol as a reducing agent, both terminal and internal vicinal diols are deoxygenated to olefins in good yield. The optional addition of acid (TsOH, H(2)SO(4)) provides access to lower reaction temperatures. This new system enables the transformation of a four-carbon sugar polyol into an oxygen-reduced compound, providing promising evidence for its practical application to produce unsaturated compounds from biomass-derived materials.

  20. The spectral emittance and stability of coatings and textured surfaces for thermophotovoltaic (TPV) radiator applications

    SciTech Connect

    Cockeram, B.V.; Hollenbeck, J.L.

    2000-11-01

    Coatings or surface modifications are needed to improve the surface emissivity of materials under consideration for TPV radiator applications to a value of 0.8 or higher. Vacuum plasma spray coatings (ZrO{sub 2} + 18% TiO{sub 2} + 10% Y{sub 2}O{sub 3}, ZrC, Fe{sub 2}TiO{sub 5}, ZrTiO{sub 4}, ZrO{sub 2} + 8% Y{sub 2}O{sub 3} + 2% HfO{sub 2}, and Al{sub 2}O{sub 3} + TiO{sub 2}) and a chemical vapor deposited coating of rhenium whiskers were used to increase the surface emissivity of refractory metal and nickel-base materials. Emittance measurements following 4000 hours of vacuum annealing at 1100 C show that only the ZrO{sub 2} + 18% TiO{sub 2} + 10% Y{sub 2}O{sub 3}, ZrC, and Al{sub 2}O{sub 3} + TiO{sub 2} coatings have the desired thermal stability, and maintain emissivity values higher than 0.8. These coatings are graybody emitters, and provide a high emissivity value in the wavelength range that is relevant to the TPV cells. The highest emissivity values were observed for the Al{sub 2}O{sub 3} + TiO{sub 2} coatings, with post-anneal values higher than graphite.

  1. Diamond Coatings

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Advances in materials technology have demonstrated that it is possible to get the advantages of diamond in a number of applications without the cost penalty, by coating and chemically bonding an inexpensive substrate with a thin film of diamond-like carbon (DLC). Diamond films offer tremendous technical and economic potential in such advances as chemically inert protective coatings; machine tools and parts capable of resisting wear 10 times longer; ball bearings and metal cutting tools; a broad variety of optical instruments and systems; and consumer products. Among the American companies engaged in DLC commercialization is Diamonex, Inc., a diamond coating spinoff of Air Products and Chemicals, Inc. Along with its own proprietary technology for both polycrystalline diamond and DLC coatings, Diamonex is using, under an exclusive license, NASA technology for depositing DLC on a substrate. Diamonex is developing, and offering commercially, under the trade name Diamond Aegis, a line of polycrystalline diamond-coated products that can be custom tailored for optical, electronic and engineering applications. Diamonex's initial focus is on optical products and the first commercial product is expected in late 1990. Other target applications include electronic heat sink substrates, x-ray lithography masks, metal cutting tools and bearings.

  2. Radiofluorinated rhenium cyclized α-MSH analogues for PET imaging of melanocortin receptor 1.

    PubMed

    Ren, Gang; Liu, Shuanlong; Liu, Hongguang; Miao, Zheng; Cheng, Zhen

    2010-12-15

    In order to accomplish in vivo molecular imaging of melanoma biomarker melanocortin 1 receptor (MC1R), several α-melanocyte-stimulating hormone (α-MSH) analogues have been labeled with N-succinimidyl-4-¹⁸F-fluorobenzoate (¹⁸)F-SFB) and studied as positron emission tomography (PET) probes in our recent studies. To further pursue a radiofluorinated α-MSH peptide with high clinical translation potential, we utilized 4-nitrophenyl 2-¹⁸F-fluoropropionate (¹⁸F-NFP) to radiofluorinate the transition metal rhenium cyclized α-MSH metallopeptides for PET imaging of MC1R positive malignant melanoma. Metallopeptides Ac-d,Lys-ReCCMSH(Arg¹¹) (two isomers, namely RMSH-1 and RMSH-2) were synthesized using conventional solid phase peptide synthesis chemistry and rhenium cyclization reaction. The two isomers were then conjugated with ¹⁹F-NFP or ¹⁸F-NFP. The resulting cold or radiofluorinated metallopeptides, (¹⁸/¹⁹)F-FP-RMSH-1 and (¹⁸/¹⁹)F-FP-RMSH-2, were further evaluated for their in vitro receptor binding affinities, in vivo biodistribution, and small-animal PET imaging properties. The binding affinities of ¹⁹F-FP-RMSH-1 and ¹⁹F-FP-RMSH-2 were determined to be within low nanomolar range. In vivo studies revealed that both F-labeled metallopeptides possessed good tumor uptake in the B16F10 murine model with high MC1R expression, while possessing much lower uptake in A375M human melanoma xenografts. Moreover, ¹⁸F-FP-RMSH-1 displayed more favorable in vivo performance in terms of higher tumor uptake and much lower accumulation in the kidney and liver, when compared to that of ¹⁸F-FP-RMSH-2 at 2 h postinjection (p.i.). ¹⁸F-FP-RMSH-1 also displayed lower liver and lung uptake when compared with that of the same peptide labeled with ¹⁸F-SFB (named as ¹⁸F-FB-RMSH-1). Small animal PET imaging of ¹⁸F-FP-RMSH-1 in mice bearing B16F10 tumors at 1 and 2 h showed good tumor imaging quality. As expected, much lower tumor uptake and

  3. Radiofluorinated Rhenium Cyclized α-MSH Analogs for PET Imaging of Melanocortin Receptor 1

    PubMed Central

    Ren, Gang; Liu, Shuanlong; Liu, Hongguang; Miao, Zheng; Cheng, Zhen

    2010-01-01

    In order to accomplish in vivo molecular imaging of melanoma biomarker melanocortin 1 receptor (MC1R), several alpha-melanocyte-stimulating hormone (α-MSH) analogs have been labeled with N-succinimidyl-4-18F-fluorobenzoate (18F-SFB) and studied as positron emission tomography (PET) probes in our recent studies. To further pursue a radiofluorinated α-MSH peptide with high clinical translation potential, we utilized 4-nitrophenyl 2-18F-fluoropropionate (18F-NFP) to radiofluorinate the transition metal rhenium cyclized α-MSH metallopeptides for PET imaging of MC1R positive malignant melanoma. Methods Metallopeptides Ac-d,Lys-ReCCMSH(Arg11) (two isomers, namely RMSH-1 and RMSH-2) were synthesized using conventional solid phase peptide synthesis chemistry and rhenium cyclization reaction. The two isomers were then conjugated with 19F-NFP or 18F-NFP. The resulting cold or radiofluorinated metallopeptides, 18/19F-FP-RMSH-1 and 18/19F-FP-RMSH-2 were further evaluated for their in vitro receptor binding affinities, in vivo biodistribution and small-animal PET imaging properties. Results The binding affinities of the 19F-FP-RMSH-1 and 19F-FP-RMSH-2) were determined to be within low nM range. In vivo studies revealed that both 18F-labeled metallopeptides possessed good tumor uptake in B16F10 murine model with high MC1R expression, while much lower uptake in A375M human melanoma xenografts. Moreover, 18F-FP-RMSH-1 displayed more favorable in vivo performance in terms of higher tumor uptake and much lower accumulation in kidney and liver, when compared to 18F-FP-RMSH-2 at 2 h post-injection (p.i.). 18F-FP-RMSH-1 also displayed lower liver and lung uptake when compared with the same peptide labeled with 18F-SFB (named as 18F-FB-RMSH-1). Small animal PET imaging of 18F-FP-RMSH-1 in mice bearing B16F10 tumors at 1 and 2 h showed good tumor imaging quality. As expected, much lower tumor uptake and poorer tumor/normal organs contrast were observed for A375M model than that of B16

  4. Rhenium and technetium complexes with N,N-dialkyl-N'-benzoylthioureas.

    PubMed

    Nguyen, Huy Hung; Abram, Ulrich

    2007-06-25

    N,N-Dialkyl-N'-benzoylthioureas, HR(1)R(2)btu, react under single deprotonation and form air-stable chelate complexes with common rhenium or technetium complexes such as (NBu(4))[MOCl(4)] (M = Re, Tc) or [ReOCl(3)(PPh(3))(2)]. Compositions and molecular structures of the products are strongly dependent on the precursors used and the reaction conditions applied. Reactions with [ReOCl(3)(PPh(3))(2)] in CH(2)Cl(2) give complexes of the general formula [ReOCl(2)(R(1)R(2)btu)(PPh(3))] (3), with the benzoyl oxygen atom of the chelating benzoylthiourea being trans to the oxo ligand, and/or Re(III) complexes of the composition [ReCl(2)(R(1)R(2)btu)(PPh(3))(2)] (4) with the PPh(3) ligands in trans positions to each other. In polar solvents such as MeOH, EtOH or acetone, corresponding reactions without addition of a supporting base only result in intractable brown solutions, from which no crystalline complexes could be isolated. The addition of NEt(3), however, allows the isolation of the bis-chelates [ReOCl(R(1)R(2)btu)(2)] (1) in good yields. In this type of complex, one of the chelating R(1)R(2)btu- ligands coordinates equatorially, while the second occupies the position trans to the oxo ligand with its oxygen atom. The latter compounds can also be prepared from (NBu(4))[ReOCl(4)] in MeOH when no base is added, while the addition of NEt(3) results in the formation of [ReO(OMe)(R(1)R(2)btu)(2)] (5) complexes with the methoxo ligand trans to O(2-). Compounds of the type 5 can alternatively be prepared by heating 1 in MeOH with addition of NEt(3). A reversible conversion of 5 into oxo-bridged dimers of the composition [{ReO(R(1)R(1)btu)(2)}(2)O] (6) is observed in water-containing solvents. Starting from (NBu(4))[TcOCl(4)], a series of technetium complexes of the type [TcOCl(R(1)R(2)btu)(2)] (2) could be prepared. The structures of such compounds are similar to those of the rhenium analogues 1. Reduction of 2 with PPh(3) in CH(2)Cl(2) gives Tc(III) complexes of the

  5. Impact of Different Standard Type A7A Drum Closure-Ring Practices on Gasket Contraction and Bolt Closure Distance– 15621

    SciTech Connect

    Ketusky, Edward; Blanton, Paul; Bobbitt, John H.

    2015-03-11

    The Department of Energy, the Savannah River National Laboratory, several manufacturers of specification drums, and the United States Department of Transportation (DOT) are collaborating in the development of a guidance document for DOE contractors and vendors who wish to qualify containers to DOT 7A Type A requirements. Currently, the effort is focused on DOT 7A Type A 208-liter (55-gallons) drums with a standard 12-gauge bolted closure ring. The U.S. requirements, contained in Title 49, Part 178.350 “Specification 7A; general packaging, Type A specifies a competent authority review of the packaging is not required for the transport of (Class 7) radioactive material containing less than Type A quantities of radioactive material. For Type AF drums, a 4 ft. regulatory free drop must be performed, such that the drum “suffers maximum damage.” Although the actual orientation is not defined by the specification, recent studies suggest that maximum damage would result from a shallow angle top impact, where kinetic energy is transferred to the lid, ultimately causing heavy damage to the lid, or even worse, causing the lid to come off. Since each vendor develops closure recommendations/procedures for the drums they manufacture, key parameters applied to drums during closing vary based on vendor. As part of the initial phase of the collaboration, the impact of the closure variants on the ability of the drum to suffer maximum damage is investigated. Specifically, closure testing is performed varying: 1) the amount of torque applied to the closure ring bolt; and, 2) stress relief protocol, including: a) weight of hammer; and, b) orientation that the hammer hits the closure ring. After closure, the amount of drum lid gasket contraction and the distance that the closure bolt moves through the closure ring is measured.

  6. Rapid identification of additives in poly(vinyl chloride) lid gaskets by direct analysis in real time ionisation and single-quadrupole mass spectrometry.

    PubMed

    Rothenbacher, Thorsten; Schwack, Wolfgang

    2010-01-01

    Gaskets for lids of glass jars usually consist of poly(vinyl chloride) (PVC) containing plasticisers and additional additives, which may migrate into packed foodstuffs. To conform to legal regulations, any such migration has to be determined analytically, which is a big challenge due to the huge chemical variety of additives in use. Therefore, a rapid screening method by means of direct analysis in real time mass spectrometry (DART-MS), using a single-quadrupole mass spectrometer, was developed. On introducing a plastisol sample into the DART interface, protonated molecules and ammonium adducts were obtained as the typical ionisation products of any additives present, and cleavages of ester bonds as typical fragmentation processes. Generally, additives present in the 1% range could be directly and easily identified if ion suppressive effects deriving from specific molecules did not occur. These effects could be avoided by analysing toluene extracts of plastisol samples, and this also improved the sensitivity. Using this method, it was possible to identify phthalates, fatty acid amides, tributyl O-acetylcitrate, dibutyl sebacate, bis(2-ethylhexyl) adipate, 1,2-diisononyl 1,2-cyclohexanedicarboxylate, and even more complex additives like acetylated mono- and diacylglycerides, epoxidised soybean oil, and polyadipates, with a limit of detection of < or = 1% in PVC plastisols. Only in the case of epoxidised linseed oil were levels of > or = 5% required for identification. The detection of azodicarbonamide, used as a foaming agent within the manufacturing process, was possible in principle, but was not highly reproducible due to the very low concentrations in plastisols.

  7. Rhenium and technetium tricarbonyl complexes of N-heterocyclic carbene ligands.

    PubMed

    Chan, Chung Ying; Pellegrini, Paul A; Greguric, Ivan; Barnard, Peter J

    2014-10-20

    A strategy for the conjugation of N-heterocyclic carbene (NHC) ligands to biomolecules via amide bond formation is described. Both 1-(2-pyridyl)imidazolium or 1-(2-pyridyl)benzimidazolium salts functionalized with a pendant carboxylic acid group were prepared and coupled to glycine benzyl ester using 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide. A series of 10 rhenium(I) tricarbonyl complexes of the form [ReX(CO)3(ĈN)] (ĈN is a bidentate NHC ligand, and X is a monodentate anionic ligand: Cl(-), RCO2(-)) were synthesized via a Ag2O transmetalation protocol from the Re(I) precursor compound Re(CO)5Cl. The synthesized azolium salts and Re(I) complexes were characterized by elemental analysis and by (1)H and (13)C NMR spectroscopy, and the molecular structures for one imidazolium salt and seven Re(I) complexes were determined by single-crystal X-ray diffraction. (1)H NMR and mass spectrometry studies for an acetonitrile-d3 solution of [ReCl(CO)3(1-(2-pyridyl)-3-methylimidazolylidene)] show that the monodentate chloride ligand is labile and exchanges with this solvent yielding a cationic acetonitrile adduct. For the first time the labeling of an NHC ligand with technetium-99m is reported. Rapid Tc-99m labeling was achieved by heating the imidazolium salt 1-(2-pyridyl)-3-methylimidazolium iodide and Ag2O in methanol, followed by the addition of fac-[(99m)Tc(OH2)3(CO)3](+). To confirm the structure of the (99m)Tc-labeled complex, the equivalent (99)Tc complex was prepared, and mass spectrometric studies showed that the formed Tc complexes are of the form [(99m/99)Tc(CH3CN)(CO)3(1-(2-pyridyl)-3-methylimidazolylidene)](+) with an acetonitrile molecule coordinated to the metal center.

  8. Layer-by-layer deposition of rhenium-containing hyperbranched polymers and fabrication of photovoltaic cells.

    PubMed

    Tse, Chui Wan; Man, Ka Yan Kitty; Cheng, Kai Wing; Mak, Chris S K; Chan, Wai Kin; Yip, Cho Tung; Liu, Zheng Tong; Djurisić, Aleksandra B

    2007-01-01

    Multilayer thin films were prepared by the layer-by-layer (LBL) deposition method using a rhenium-containing hyperbranched polymer and poly[2-(3-thienyl)ethoxy-4-butylsulfonate] (PTEBS). The radii of gyration of the hyperbranched polymer in solutions with different salt concentrations were measured by laser light scattering. A significant decrease in molecular size was observed when sodium trifluoromethanesulfonate was used as the electrolyte. The conditions of preparing the multilayer thin films by LBL deposition were studied. The growth of the multilayer films was monitored by absorption spectroscopy and spectroscopic ellipsometry, and the surface morphologies of the resulting films were studied by atomic force microscopy. When the pH of a PTEBS solution was kept at 6 and in the presence of salt, polymer films with maximum thickness were obtained. The multilayer films were also fabricated into photovoltaic cells and their photocurrent responses were measured upon irradiation with simulated air mass (AM) 1.5 solar light. The open-circuit voltage, short-circuit current, fill factor, and power conversion efficiency of the devices were 1.2 V, 27.1 mu A cm(-2), 0.19, and 6.1x10(-3) %, respectively. The high open-circuit voltage was attributed to the difference in the HOMO level of the PTEBS donor and the LUMO level of the hyperbranched polymer acceptor. A plot of incident photon-to-electron conversion efficiency versus wavelength also suggests that the PTEBS/hyperbranched polymer junction is involved in the photosensitization process, in which a maximum was observed at approximately 420 nm. The relatively high capacitance, determined from the measured photocurrent rise and decay profiles, can be attributed to the presence of large counter anions in the polymer film.

  9. Interventional Therapy of Head and Neck Cancer with Lipid Nanoparticle-Carried Rhenium-186 Radionuclide

    PubMed Central

    French, J. Tyler; Goins, Beth; Saenz, Marcela; Li, Shihong; Garcia-Rojas, Xavier; Phillips, William T.; Otto, Randal A.; Bao, Ande

    2010-01-01

    Purpose Minimally invasive interventional cancer therapy of drug-carrying lipid nanoparticles (liposomes) via convection enhanced delivery generally applied by the use of an infusion pump can increase intratumoral drug concentration and retention while facilitating broad distribution throughout solid tumors. We investigated the utility of liposome-carrying β-emitting radionuclides to treat head and neck cancer in nude rats by direct intratumoral infusion. Methods Four groups of nude rats were subcutaneously inoculated with human tongue cancer cells. After tumors reached an average size of 1.6 cm3, the treatment group received an intratumoral infusion of liposomal rhenium-186 (186Re) (185 MBq (5 mCi)/cm3 tumor). Three control groups were intratumorally infused with either, 1) unlabeled liposomes, 2) unencapsulated 186Re-perrhenate, or 3) unencapsulated intermediate 186Re-compound (186Re-BMEDA). In vivo distribution of 186Re-activity was measured by planar gamma camera imaging. Tumor therapy and toxicity were assessed by measurements of tumor size, body weight, and hematology. Results Average tumor volume of the 186Re-liposome group on post-treatment day-14 decreased to 87.7±20.1%, while tumor volumes increased to 395.0% - 514.4% on average in other three groups (P<0.001 vs 186Re-liposome group). 186Re-liposomes provided much higher intratumoral retention of 186Re-activity, resulting in an average tumor radiation absorbed dose of 526.3±93.3 Gy, whereas 186Re-perrhenate and 186Re-BMEDA groups had only 3.3±1.2 and 13.4±9.2 Gy tumor doses respectively. No systemic toxicity was observed. Conclusion Liposomal 186Re effectively treated the head and neck cancer with minimal side effects after convection enhanced interventional delivery. These results suggest the potential of liposomal 186Re for clinical application in interventional therapy of cancer. PMID:20478719

  10. Design and characterization of α-melanotropin peptide analogs cyclized through rhenium and technetium metal coordination

    PubMed Central

    Giblin, Michael F.; Wang, Nannan; Hoffman, Timothy J.; Jurisson, Silvia S.; Quinn, Thomas P.

    1998-01-01

    α-Melanocyte stimulating hormone (α-MSH) analogs, cyclized through site-specific rhenium (Re) and technetium (Tc) metal coordination, were structurally characterized and analyzed for their abilities to bind α-MSH receptors present on melanoma cells and in tumor-bearing mice. Results from receptor-binding assays conducted with B16 F1 murine melanoma cells indicated that receptor-binding affinity was reduced to approximately 1% of its original levels after Re incorporation into the cyclic Cys4,10, d-Phe7–α-MSH4-13 analog. Structural analysis of the Re–peptide complex showed that the disulfide bond of the original peptide was replaced by thiolate–metal–thiolate cyclization. A comparison of the metal-bound and metal-free structures indicated that metal complexation dramatically altered the structure of the receptor-binding core sequence. Redesign of the metal binding site resulted in a second-generation Re–peptide complex (ReCCMSH) that displayed a receptor-binding affinity of 2.9 nM, 25-fold higher than the initial Re–α-MSH analog. Characterization of the second-generation Re–peptide complex indicated that the peptide was still cyclized through Re coordination, but the structure of the receptor-binding sequence was no longer constrained. The corresponding 99mTc- and 188ReCCMSH complexes were synthesized and shown to be stable in phosphate-buffered saline and to challenges from diethylenetriaminepentaacetic acid (DTPA) and free cysteine. In vivo, the 99mTcCCMSH complex exhibited significant tumor uptake and retention and was effective in imaging melanoma in a murine-tumor model system. Cyclization of α-MSH analogs via 99mTc and 188Re yields chemically stable and biologically active molecules with potential melanoma-imaging and therapeutic properties. PMID:9788997

  11. Radiosynoviorthesis in hemophilic joints with yttrium-90 citrate and rhenium-186 sulfide and long term results.

    PubMed

    Teyssler, Petr; Taborska, Katerina; Kolostova, Katarina; Bobek, Vladimir

    2013-01-01

    Repeated bleeding in the joint cavities is the most annoying symptom and often has disabling effects in patients with hemophilia (PWH). Our aim was to study the effect of radiosynovectomy (RSO) with beta particle-emitting radiocolloids in the treatment of hemorhagic arthropathy. We have treated 22 joints from 18 patients with hemophilia A, from April 2008 to February 2012, 5 knees, 11 elbows and 6 ankles. Joints were divided into two Groups, those treated with yttrium-90-citrate ((90)Y-C) (5 knees, 2 of them twice)-Group I and those with rhenium-186-sulfide ((186)Re-S) (11 elbows, 1 of them treated twice and 6 ankles)-Group II. A total of 25 treatments. Follow-up period was 3 months, 1 year and 3 years. Results showed a favourable subjective and a better objective result in all 5 joints of Group I and in 15/17 joints of Group II, respectively. Follow-up after 3 months showed significant improvement in Hemophilia Join Health Score (HJHS) after 20 treatments and steady score after 5 treatments. After 1 year, 19 treated joints had improved for the first time, 3 remained steady and 3 were not examined. After 3 years, 9 treated joints were HJHS steady, while 16 were not examined. One year after treatment, 13/14 joints of patients, aged 6-23 years showed better HJHS score, while 9/11 joints of patients aged 26-51 years, showed better HJHS. Synovial membrane thickness as measured by MRI in 8 joints, before and 3 months after treatment was not related to prognosis. In conclusion, in a small group of hemophilic patients with hemorrhagic arthropathy treated with (90)Y-C and with (186)Re-S, our study showed good results irrespective of age in 22/25 treatments after 3 months or 1 year. The thickness of synovial membrane in the 8 joints studied was not related to prognosis.

  12. Rhenium complexes of bidentate, bis-bidentate and tridentate N-heterocyclic carbene ligands.

    PubMed

    Chan, Chung Ying; Barnard, Peter J

    2015-11-28

    A series of eight Rhenium(I)-N-heterocyclic carbene (NHC) complexes of the general form [ReCl(CO)3(C^C)] (where C^C is a bis(NHC) bidentate ligand), [ReCl(CO)3(C^C)]2 (where C^C is a bis-bidentate tetra-NHC ligand) and [Re(CO)3(C^N^C)](+)[X](-) (where C^N^C is a bis(NHC)-amine ligand and the counter ion X is either the ReO4(-) or PF6(-)) have been synthesised using a Ag2O transmetallation protocol. The novel precursor imidazolium salts and Re(I) complexes were characterized by elemental analysis, (1)H and (13)C NMR spectroscopy and the molecular structures for two imidazolium salt and six Re(I) complexes were determined by single crystal X-ray diffraction. These NHC ligand systems are of interest for possible applications in the development of Tc-99m or Re-186/188 radiopharmaceuticals and as such the stability of two complexes of the form [ReCl(CO)3(C^C)] and [Re(CO)3(C^N^C)][ReO4] were evaluated in ligand challenge experiments using the metal binding amino acids L-histidine or L-cysteine. These studies showed that the former was unstable, with the chloride ligand being replaced by either cysteine or histidine, while no evidence for transchelation was observed for the latter suggesting that bis(NHC)-amine ligands of this type may be suitable for biological applications.

  13. Biological dosimetry after radiosynoviorthesis with rhenium-186 sulphide and erbium-169 citrate.

    PubMed

    Klett, R; Schnurbus-Duhs, A; Mödder, G; Schmid, E; Voth, M

    2012-01-01

    Radiosynoviorthesis (RSO) with the nuclides rhenium-186 sulphide (186Re) and erbium-169 citrate (169Er) is an established concept for the treatment of persistent synovitis of medium and small sized joints. THE AIM of the present studies was to investigate the biological radiation effect based on analysing chromosome aberrations. Immediately before and 17 to 19 days (186Re) or 45 to 50 (169Er) days after RSO with 186Re or 169Er colloid and subsequent immobilisation of the treated joint, blood samples of a total of 23 patients were collected. The yield of dicentric chromosomes in lymphocytes was determined exclusively in metaphases of the first cell cycle in vitro. In addition, for 186Re the activity leakage was measured three days after RSO by whole-body scintigraphy. No statistically significant increase in the number of dicentric chromosomes (40 and 88 before and 59 and 105 after treatment with 186Re and 169Er, respectively) in a total of 47017 cells analysed from 46 blood samples could be found as a result of RSO. For 186Re an activity leakage of 3.9%±7% with a maximum of 23.4% corresponding to an effective dose of 2.8±4.5 mSv , respectively 13.8 mSv, was determined. Also in the case of the maximum leakage no significant increase of dicentric chromosomes were detected. No significant biological radiation effect can be detected after RSO with 186Re and 169Er, also in cases of high leakage. Therefore, RSO can be classified as a save therapeutic procedure without a relevant radiation risk.

  14. Dissolved rhenium in river waters: Insight into the chemical weathering of fossil organic carbon?

    NASA Astrophysics Data System (ADS)

    Hilton, Robert; Gaillardet, Jerome

    2010-05-01

    The store of carbon in rock as fossil organic matter represents ~15x1021 g, which is almost 400 times the total amount of carbon present in the oceans and atmosphere. Oxidation of fossil organic carbon (FOC) during chemical weathering returns CO2 that was sequestered from the atmosphere in the geological past, back into the contemporary carbon cycle. Despite this recognition, the natural rates of FOC weathering are poorly constrained in the modern environment, as are the precise controls on its variability. This is primarily due to the difficultly in tracking the dissolved and gaseous carbon produced during FOC weathering, where biology and carbonate weathering mask its influence at a catchment-scale. Here we investigate the use of rhenium (Re) as a tracer of FOC weathering, focusing on a series of mountain catchments in Taiwan. We present dual methodology for determining dissolved Re content in river waters by ICP-MS, using pre-concentration and matrix removal via anion exchange chemistry and by direct analysis through standard-addition. Precision (2sigma) and accuracy at the ppt level are found to be better than 7%. In the 16 sampled catchments, the dissolved Re concentrations span the entire range from the published literature. We investigate the source of dissolved Re in the catchments using measurements of bedrocks and river sediments, and the comparative behavior of Re to major dissolved phases. A preliminary estimate of the Re budget derived from the weathering of FOC is presented, and the implications for the rates of FOC weathering discussed.

  15. Interventional therapy of head and neck cancer with lipid nanoparticle-carried rhenium 186 radionuclide.

    PubMed

    French, J Tyler; Goins, Beth; Saenz, Marcela; Li, Shihong; Garcia-Rojas, Xavier; Phillips, William T; Otto, Randal A; Bao, Ande

    2010-08-01

    Minimally invasive interventional cancer therapy with drug-carrying lipid nanoparticles (ie, liposomes) via convection-enhanced delivery by an infusion pump can increase intratumoral drug concentration and retention while facilitating broad distribution throughout solid tumors. The authors investigated the utility of liposome-carrying beta-emitting radionuclides to treat head and neck cancer by direct intratumoral infusion in nude rats. Four groups of nude rats were subcutaneously inoculated with human tongue cancer cells. After tumors reached an average size of 1.6 cm(3), the treatment group received an intratumoral infusion of liposomal rhenium-186 ((186)Re) (185 MBq [5 mCi]/cm(3) tumor). Three control groups were intratumorally infused with unlabeled liposomes, unencapsulated (186)Re-perrhenate, or unencapsulated intermediate (186)Re compound ((186)Re-N,N-bis[2-mercaptoethyl]-N',N'-diethyl-ethylenediamine [BMEDA]). In vivo distribution of (186)Re activity was measured by planar gamma-camera imaging. Tumor therapy and toxicity were assessed by tumor size, body weight, and hematology. Average tumor volume in the (186)Re-liposome group on posttreatment day 14 decreased to 87.7% +/- 20.1%, whereas tumor volumes increased to 395.0%-514.4% on average in the other three groups (P< .001 vs (186)Re-liposome). The (186)Re-liposomes provided much higher intratumoral retention of (186)Re activity, resulting in an average tumor radiation absorbed dose of 526.3 Gy +/- 93.3, whereas (186)Re-perrhenate and (186)Re-BMEDA groups had only 3.3 Gy +/- 1.2 and 13.4 Gy +/- 9.2 tumor doses, respectively. No systemic toxicity was observed. Liposomal (186)Re effectively treated head and neck cancer with minimal side effects after convection-enhanced interventional delivery. These results suggest the potential of liposomal (186)Re for clinical application in interventional therapy of cancer. Copyright (c) 2010 SIR. Published by Elsevier Inc. All rights reserved.

  16. Rhenium, molybdenum, and uranium in groundwater from the southern Great Basin, USA: Evidence for conservative behavior

    SciTech Connect

    Hodge, V.F.; Johannesson, K.H.; Stetzenbach, K.J.

    1996-09-01

    Dissolved Re, Mo, and U concentrations, and the concentrations of the major cations and anions, were measured in groundwaters from twenty-three springs in the southern Great Basin, USA, from June 1992 through March 1994. Rhenium concentrations ranged from 5 {plus_minus} 1 pmol/kg to 190 {plus_minus} 20 pmol/kg. The highest Re values were observed in the saline groundwater of Saratoga Spring in Death Valley and Cold Spring in Ash Meadows, whereas the lowest Re concentrations were found in Nevares Spring in Death Valley. The mean Re concentration for all of the spring waters sampled is 44 {plus_minus} 33 pmol/kg. The concentrations of Re differs dramatically for groundwaters that discharge from the regional Paleozoic carbonate aquifer and for local groundwaters from felsic volcanic rocks. The mean Re concentration for groundwaters issuing from the carbonate aquifer is 37 {plus_minus} 14 pmol/kg (which is similar to the average Re value reported for seawater, i.e., 39.8 {plus_minus} 0.2 pmol/kg), whereas for the spring waters that discharge from the felsic volcanic aquifers, the mean Re concentration is 18 {plus_minus} 3.5 pmol/kg. Groundwaters discharging from the regional carbonate aquifer in Ash Meadows typically exhibit a U/Re ratio of about 300 while groundwaters that discharge in Death Valley from local felsic volcanic sources have ratios of about 1700. Waters in the remainder of the Death Valley springs are intermediated and may result from the mixing of the carbonate and volcanic derived waters. The substantially larger salinity normalized Re, Mo, and U concentrations in the groundwaters compared to seawater, rule out the possibility that these groundwaters represent simple mixing of dilute terrestrial waters and seawaters or reconstitution of evaporite deposits by groundwater dissolution. 65 refs., 9 figs., 2 tabs.

  17. Rhenium(I) tricarbonyl compounds of bioactive thiosemicarbazones: Synthesis, characterization and activity against Trypanosoma cruzi.

    PubMed

    Rodríguez Arce, Esteban; Machado, Ignacio; Rodríguez, Belén; Lapier, Michel; Zúñiga, María Carolina; Maya, Juan Diego; Olea Azar, Claudio; Otero, Lucía; Gambino, Dinorah

    2017-05-01

    American Trypanosomiasis is a chronic infection discovered and described in 1909 by the Brazilian scientist Carlos Chagas. It is caused by the protozoan parasite Trypanosoma cruzi. Although it affects about 10million people in Latin America, the current chemotherapy is still inadequate. The discovery of new drugs is urgently needed. Our group is focused on the development of prospective metal-based drugs mainly based on bioactive ligands and pharmacologically interesting metal ions. In this work three new rhenium(I) tricarbonyl compounds fac-[Re(I)(CO)3Br(HL)] where HL=5-nitrofuryl containing thiosemicarbazones were synthesized and fully characterized in solution and in the solid state. The in vitro evaluation of the compounds on T. cruzi trypomastigotes (Dm28c strain) showed that the Re(I) compounds are 8 to 15 times more active than the reference drug Nifurtimox and show a 4 to 17 fold increase in activity in respect to the free (HL) ligands. Obtained compounds also show good selectivity indexes (IC50 endothelial cells Ea.hy926/IC50 T. cruzi (Dm28c tripomastigotes)). (1)H NMR and MS studies, performed with time, showed that the fac-[Re(CO)3Br(HL)] species convert into the dimers [Re2(CO)6(L)2] in solution. Crystal structure of [Re(I)2(CO)6(L2)2], the product of complexes' dimerization, was solved. Related to the mechanism of action, the studied compounds do not generate radical oxygen species in the parasite (as 5-nitrofuryl derived thiosemicarbazones do) probably due to the unfavorable nitro reduction potential of the generated dimeric species. On the contrary, the compounds produce a decrease of the oxygen consumption rate of the parasites, maybe inhibiting their mitochondrial respiration.

  18. Design and characterization of alpha-melanotropin peptide analogs cyclized through rhenium and technetium metal coordination.

    PubMed

    Giblin, M F; Wang, N; Hoffman, T J; Jurisson, S S; Quinn, T P

    1998-10-27

    alpha-Melanocyte stimulating hormone (alpha-MSH) analogs, cyclized through site-specific rhenium (Re) and technetium (Tc) metal coordination, were structurally characterized and analyzed for their abilities to bind alpha-MSH receptors present on melanoma cells and in tumor-bearing mice. Results from receptor-binding assays conducted with B16 F1 murine melanoma cells indicated that receptor-binding affinity was reduced to approximately 1% of its original levels after Re incorporation into the cyclic Cys4,10, D-Phe7-alpha-MSH4-13 analog. Structural analysis of the Re-peptide complex showed that the disulfide bond of the original peptide was replaced by thiolate-metal-thiolate cyclization. A comparison of the metal-bound and metal-free structures indicated that metal complexation dramatically altered the structure of the receptor-binding core sequence. Redesign of the metal binding site resulted in a second-generation Re-peptide complex (ReCCMSH) that displayed a receptor-binding affinity of 2.9 nM, 25-fold higher than the initial Re-alpha-MSH analog. Characterization of the second-generation Re-peptide complex indicated that the peptide was still cyclized through Re coordination, but the structure of the receptor-binding sequence was no longer constrained. The corresponding 99mTc- and 188ReCCMSH complexes were synthesized and shown to be stable in phosphate-buffered saline and to challenges from diethylenetriaminepentaacetic acid (DTPA) and free cysteine. In vivo, the 99mTcCCMSH complex exhibited significant tumor uptake and retention and was effective in imaging melanoma in a murine-tumor model system. Cyclization of alpha-MSH analogs via 99mTc and 188Re yields chemically stable and biologically active molecules with potential melanoma-imaging and therapeutic properties.

  19. A novel series of rhenium-bipyrimidine complexes: synthesis, crystal structure and electrochemical properties.

    PubMed

    Chiozzone, Raúl; González, Ricardo; Kremer, Carlos; Cerdá, María Fernanda; Armentano, Donatella; De Munno, Giovanni; Martínez-Lillo, José; Faus, Juan

    2007-02-14

    Four novel rhenium complexes of formula [ReCl(4)(bpym)] (1), [ReBr(4)(bpym)] (2) PPh(4)[ReCl(4)(bpym)] (3) and NBu(4)[ReBr(4)(bpym)] (4) (bpym = 2,2'-bipyrimidine, PPh(4) = tetraphenylphosphonium cation and NBu(4) = tetrabutylammonium cation), have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. The structures of 1 and 2 consist of [ReX(4)(bpym)] molecules held together by van der Waals forces. In both complexes the Re(iv) central atom is surrounded by four halide anions and two nitrogen atoms of a bpym bidentate ligand in a distorted octahedral environment. The structures of 3 and 4 consist of [ReX(4)(bpym)](-) anions and PPh(4)(+) () or NBu(4)(+) (4) cations. The coordination sphere of the Re(iii) metal ion is the same as in 1 and 2, respectively. However, whereas the Re-X bonds are longer the Re-N bonds are shorter than in 1 and 2. This fact reveals that the bpym ligand forms a stronger bond with Re(iii) than with Re(iv) resulting in a stabilisation of the lower oxidation state. [ReX(4)(bpym)] complexes are easily reduced, chemically and electrochemically, to the corresponding [ReX(4)(bpym)](-) anions. A voltammetric study shows that the electron transference is a reversible process characterized by formal redox potentials of +0.19 V (1) and +0.32 V (2) vs. NHE, in acetonitrile as solvent.

  20. Probing the catalytic potential of chloro nitrosyl rhenium(I) complexes.

    PubMed

    Jiang, Yanfeng; Blacque, Olivier; Berke, Heinz

    2011-03-21

    The reduction of the mononitrosyl Re(II) salt [NMe(4)](2)[ReCl(5)(NO)] (1) with zinc in acetonitrile afforded the Re(i) dichloride complex [ReCl(2)(NO)(CH(3)CN)(3)] (2). Subsequent ligand substitution reactions with PCy(3), PiPr(3) and P(p-tolyl)(3) afforded the bisphosphine Re(i) complexes [ReCl(2)(NO)(PR(3))(2)(CH(3)CN)] (3, R = Cy a, iPr b, p-tolyl c) in good yields. The acetonitrile ligand in 3 is labile, permitting its replacement with H(2) (1 bar) to afford the dihydrogen Re(I) complexes [ReCl(2)(NO)(PR(3))(2)(η(2)-H(2))] (4, R = Cy a, iPr b). The catalytic activity of 2, 3 and 4 in hydrogen-related catalyses including dehydrocoupling of Me(2)NH·BH(3), dehydrogenative silylation of styrenes, and hydrosilylation of ketones and aryl aldehydes were investigated, with the main focus on phosphine and halide effects. In the dehydrocoupling of Me(2)NH·BH(3), the phosphine-free complex 2 exhibits the same activity as the bisphosphine-substituted systems. In the dehydrogenative silylation of styrenes, 3a and 4a bearing PCy(3) ligands exhibit high catalytic activities. Monochloro Re(I) hydrides [Re(Cl)(H)(NO)(PR(3))(2)(CH(3)CN)] (5, R = Cy a, iPr b) were proven to be formed in the initiation pathway. The phosphine-free complex 2 showed in dehydrogenative silylations even higher activity than the bisphosphine derivatives, which further emphasizes the importance of a facile phosphine dissociation in the catalytic process. In the hydrosilylation of ketones and aryl aldehydes, at least one rhenium-bound phosphine is required to ensure high catalytic activity.

  1. Protective Coatings

    NASA Technical Reports Server (NTRS)

    1980-01-01

    General Magnaplate Corporation's pharmaceutical machine is used in the industry for high speed pressing of pills and capsules. Machine is automatic system for molding glycerine suppositories. These machines are typical of many types of drug production and packaging equipment whose metal parts are treated with space spinoff coatings that promote general machine efficiency and contribute to compliance with stringent federal sanitation codes for pharmaceutical manufacture. Collectively known as "synergistic" coatings, these dry lubricants are bonded to a variety of metals to form an extremely hard slippery surface with long lasting self lubrication. The coatings offer multiple advantages; they cannot chip, peel or be rubbed off. They protect machine parts from corrosion and wear longer, lowering maintenance cost and reduce undesired heat caused by power-robbing friction.

  2. Nanostructured Coatings

    NASA Astrophysics Data System (ADS)

    Rivière, J.-P.

    In many branches of technology where surfaces are playing a growing role, the use of coatings is often the only way to provide surfaces with specific functional properties. For example, the austenitic stainless steels or titanium alloys exhibit poor resistance to wear and low hardness values, which limits the field of applications. The idea then is to develop new solutions which would improve the mechanical performance and durability of objects used in contact and subjected to mechanical forces in hostile gaseous or liquid environments. Hard coatings are generally much sought after to enhance the resistance to wear and corrosion. They are of particular importance because they constitute a class of protective coatings which is already widely used on an industrial scale to improve the hardness and lifetime of cutting tools.

  3. Gold Coating

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Epner Technology Inc. responded to a need from Goddard Space Flight Center for the ultimate in electroplated reflectivity needed for the Mars Global Surveyor Mars Orbiter Laser Altimeter (MOLA). Made of beryllium, the MOLA mirror was coated by Epner Technology Laser Gold process, specially improved for the project. Improved Laser Gold- coated reflectors have found use in an epitaxial reactor built for a large semiconductor manufacturer as well as the waveguide in Braun-Thermoscan tympanic thermometer and lasing cavities in various surgical instruments.

  4. New insights into hydrosilylation of unsaturated carbon-heteroatom (C═O, C═N) bonds by rhenium(V)-dioxo complexes.

    PubMed

    Huang, Liangfang; Wang, Wenmin; Wei, Xiaoqin; Wei, Haiyan

    2015-04-23

    The hydrosilylation of unsaturated carbon-heteroatom (C═O, C═N) bonds catalyzed by high-valent rhenium(V)-dioxo complex ReO2I(PPh3)2 (1) were studied computationally to determine the underlying mechanism. Our calculations revealed that the ionic outer-sphere pathway in which the organic substrate attacks the Si center in an η(1)-silane rhenium adduct to prompt the heterolytic cleavage of the Si-H bond is the most energetically favorable process for rhenium(V)-dioxo complex 1 catalyzed hydrosilylation of imines. The activation energy of the turnover-limiting step was calculated to be 22.8 kcal/mol with phenylmethanimine. This value is energetically more favorable than the [2 + 2] addition pathway by as much as 10.0 kcal/mol. Moreover, the ionic outer-sphere pathway competes with the [2 + 2] addition mechanism for rhenium(V)-dioxo complex 1 catalyzing the hydrosilylation of carbonyl compounds. Furthermore, the electron-donating group on the organic substrates would induce a better activity favoring the ionic outer-sphere mechanistic pathway. These findings highlight the unique features of high-valent transition-metal complexes as Lewis acids in activating the Si-H bond and catalyzing the reduction reactions.

  5. Modification of 1,2,4,5-tetrazine with cationic rhenium(I) polypyridine units to afford phosphorogenic bioorthogonal probes with enhanced reaction kinetics.

    PubMed

    Choi, Alex Wing-Tat; Tso, Karson Ka-Shun; Yim, Vicki Man-Wai; Liu, Hua-Wei; Lo, Kenneth Kam-Wing

    2015-02-25

    New phosphorogenic bioorthogonal probes derived from mononuclear and binuclear rhenium(I) polypyridine complexes containing a 1,2,4,5-tetrazine moiety were designed; these complexes displayed substantial dienophile-induced emission enhancement, and accelerated reaction kinetics and could target a protein conjugate in living cells.

  6. High activity Rhenium-186 HEDP with autologous peripheral blood stem cell rescue: a phase I study in progressive hormone refractory prostate cancer metastatic to bone

    PubMed Central

    O'Sullivan, J M; McCready, V R; Flux, G; Norman, A R; Buffa, F M; Chittenden, S; Guy, M; Pomeroy, K; Cook, G; Gadd, J; Treleaven, J; Al-Deen, A; Horwich, A; Huddart, R A; Dearnaley, D P

    2002-01-01

    We tested the feasibility and toxicity of high activities Rhenium-186 hydroxyethylidene diphosphonate, with peripheral blood stem cell rescue in patients with progressive hormone refractory prostate cancer metastatic to bone. Twenty-five patients received between 2500 and 5000 MBq of Rhenium-186 hydroxyethylidene diphosphonate followed 14 days later by the return of peripheral blood peripheral blood stem cells. Activity limiting toxicity was defined as grade III haematological toxicity, lasting at least 7 days, or grade IV haematological toxicity of any duration or any serious unexpected toxicity. Activity limiting toxicity occurred in two of six who received activities of 5000 MBq and maximum tolerated activity was defined at this activity level. Prostate specific antigen reductions of 50% or more lasting at least 4 weeks were seen in five of the 25 patients (20%) all of whom received more than 3500 MBq of Rhenium-186 hydroxyethylidene diphosphonate. The actuarial survival at 1 year is 54%. Administered activities of 5000 MBq of Rhenium-186 hydroxyethylidene diphosphonate are feasible using autologous peripheral blood peripheral blood stem cell rescue in patients with progressive hormone refractory prostate cancer metastatic to bone. The main toxicity is thrombocytopaenia, which is short lasting. A statistically significant activity/prostate specific antigen response was seen. We have now commenced a Phase II trial to further evaluate response rates. British Journal of Cancer (2002) 86, 1715–1720. doi:10.1038/sj.bjc.6600348 www.bjcancer.com © 2002 Cancer Research UK PMID:12087455

  7. Use of a new tandem cation/anion exchange system with clinical-scale generators provides high specific volume solutions of technetium-99m and rhenium-188

    SciTech Connect

    Knapp, F.R. Jr.; Beets, A.L.; Mirzadeh, S.; Guhlke, S. |

    1998-03-01

    In this paper the authors describe the first application of a simple and inexpensive post elution tandem cation-anion exchange column system which is based on generator elution with salts of weak acids such as ammonium acetate instead of saline solution to provide very high specific volume solutions of technetium-99m and rhenium-188 from clinical scale molybdenum-99/technetium-99m generator prepared from low specific activity (n,y) molybdenum-99, and tungsten-188/rhenium-188 generators, respectively. Initial passage of the bolus through a strong cation exchange cartridge converts the ammonium acetate to acetic acid which is essentially not ionized at the acidic pH, allowing specific subsequent amine type (QMA SepPak{trademark}) anion exchange cartridge column trapping of the microscopic levels of the pertechnetate or perrhenate. Subsequent elution of the anion cartridge with a small volume (< 1 mL) of saline then provides high specific volume solutions of technetium-99m by concentration of the high eluant volumes obtained by elution of clinical-scale (1 Ci) generators. This new approach also works very effectively to obtain high specific volume solutions of rhenium-188 (> 500 mCi/mL) from the alumina-based tungsten-188/rhenium-188 generator.

  8. Sequential bottom-up and top-down processing for the synthesis of transition metal dichalcogenide nanosheets: the case of rhenium disulfide (ReS2).

    PubMed

    Al-Dulaimi, Naktal; Lewis, Edward A; Lewis, David J; Howell, Simon K; Haigh, Sarah J; O'Brien, Paul

    2016-06-14

    Bottom-up (aerosol-assisted chemical vapor deposition, AACVD) and top-down (liquid phase exfoliation, LPE) processing methodologies are used in tandem to produce colloids of few-layer thick rhenium disulfide (ReS2) in N-methyl pyrrolidone. The processing route we use is a potentially robust and scalable pathway to manufacture useful 2D materials.

  9. Discovery of rhenium and masurium (technetium) by Ida Noddack-Tacke and Walter Noddack. Forgotten heroes of nuclear medicine.

    PubMed

    Biersack, H-J; Stelzner, F; Knapp, F F

    2015-01-01

    The history of the early identification of elements and their designation to the Mendeleev Table of the Elements was an important chapter in German science in which Ida (1896-1978) and Walter (1893-1960) Noddack played an important role in the first identification of rhenium (element 75, 1925) and technetium (element 43, 1933). In 1934 Ida Noddack was also the first to predict fission of uranium into smaller atoms. Although the Noddacks did not for some time later receive the recognition for the first identification of technetium-99m, their efforts have appropriately more recently been recognized. The discoveries of these early pioneers are even more astounding in light of the limited technologies and resources which were available during this period. The Noddack discoveries of elements 43 and 75 are related to the subsequent use of rhenium-188 (beta/gamma emitter) and technetium-99m (gamma emitter) in nuclear medicine. In particular, the theranostic relationship between these two generator-derived radioisotopes has been demonstrated and offers new opportunities in the current era of personalized medicine.

  10. Rhenium-188 Production in Hospitals, by W-188/Re-188 Generator, for Easy Use in Radionuclide Therapy

    PubMed Central

    Argyrou, Maria; Valassi, Alexia; Andreou, Maria; Lyra, Maria

    2013-01-01

    Rhenium-188 (Re-188) is a high energy β-emitting radioisotope obtained from the tungsten-188/rhenium-188 (W-188/Re-188) generator, which has shown utility for a variety of therapeutic applications in nuclear medicine, oncology, and interventional radiology/cardiology. Re-188 decay is accompanied by a 155 keV predominant energy γ-emission, which could be detected by γ-cameras, for imaging, biodistribution, or absorbed radiation dose studies. Its attractive physical properties and its potential low cost associated with a long-lived parent make it an interesting option for clinical use. The setup and daily use of W-188/Re-188 generator in hospital nuclear medicine departments are discussed in detail. The clinical efficacy, for several therapeutic applications, of a variety of Re-188-labeled agents is demonstrated. The high energy of the β-emission of Re-188 is particularly well suited for effective penetration in solid tumours. Its total radiation dose delivered to tissues is comparable to other radionuclides used in therapy. Furthermore, radiation safety and shielding requirements are an important subject of matter. In the case of bone metastases treatment, therapeutic ratios are presented in order to describe the efficacy of Re-188 usage. PMID:23653859

  11. Photocatalytic Conversion of CO2 to CO using Rhenium Bipyridine Platforms Containing Ancillary Phenyl or BODIPY Moieties

    SciTech Connect

    Andrade, Gabriel; Pistner, Allen; Yapp, Glenn P. A.; Lutterman, Daniel A; Rosenthal, Joel

    2013-01-01

    Harnessing of solar energy to drive the reduction of carbon dioxide to fuels requires the development of efficient catalysts that absorb sunlight. In this work, we detail the synthesis, electrochemistry and photophysical properties of a set of homologous fac-ReI(CO)3 complexes containing either an ancillary phenyl (8) or BODIPY (12) substituent. These studies demonstrate that both the electronic properties of the rhenium center and BODIPY chromophore are maintained for these systems. Photolysis studies demonstrate that both assemblies 8 and 12 are competent catalysts for the photochemical reduction of CO2 to CO in DMF using triethanolamine (TEOA) as a sacrificial reductant. Both these systems display TOFs for photocatalytic CO production upon irradiation with light ( ex 400 nm) of ~5 hr 1 with TON values of approximately 20. Although structural and photophysical measurements demonstrate that electronic coupling between the BODIPY and fac-ReI(CO)3 units is limited for complex 12, this work clearly shows that the photoactive BODIPY moiety is tolerated during catalysis and does not interfere with the observed photochemistry. When taken together, these results provide a clear roadmap for the development of advanced rhenium bipyridine complexes bearing ancillary BODIPY groups for the efficient photocatalytic reduction of CO2 using visible light.

  12. Hydrogenation of succinic acid to 1,4-butanediol over rhenium catalyst supported on copper-containing mesoporous carbon.

    PubMed

    Hong, Ung Gi; Park, Hai Woong; Lee, Joongwon; Hwang, Sunhwan; Kwak, Jimin; Yi, Jongheop; Song, In Kyu

    2013-11-01

    Copper-containing mesoporous carbon (Cu-MC) was prepared by a single-step surfactant-templating method. For comparison, copper-impregnated mesoporous carbon (Cu/MC) was also prepared by a surfactant-templating method and a subsequent impregnation method. Rhenium catalysts supported on copper-containing mesoporous carbon and copper-impregnated mesoporous carbon (Re/Cu-MC and Re/Cu/MC, respectively) were then prepared by an incipient wetness method, and they were applied to the liquid-phase hydrogenation of succinic acid to 1,4-butanediol (BDO). It was observed that copper in the Re/Cu-MC catalyst was well incorporated into carbon framework, resulting in higher surface area and larger pore volume than those of Re/Cu/MC catalyst. Therefore, Re/Cu-MC catalyst showed higher copper dispersion than Re/Cu/MC catalyst, although both catalysts retained the same amounts of copper and rhenium. In the liquid-phase hydrogenation of succinic acid to BDO, Re/Cu-MC catalyst showed a better catalytic activity than Re/Cu/MC catalyst. Fine dispersion of copper in the Re/Cu-MC catalyst was responsible for its enhanced catalytic activity.

  13. Effect of Rhenium Addition on Wear Behavior of Cr-Al2O3 Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Chmielewski, Marcin; Piątkowska, Anna

    2015-05-01

    Materials for applications in the automotive industry are required to be strong, stiff, hard, light weight, and wear resistant, which is very difficult to achieve in the case of conventional materials. To meet all these diverse requirements, it is necessary to combine various types of materials (such as metals and ceramics). In the present study, the chromium and chromium-rhenium matrices were reinforced with aluminum oxide to obtain composite materials with improved wear resistance. The composites were fabricated by a powder metallurgy method. The effects of the rhenium addition and volume fraction of aluminum oxide on the wear rate and the friction coefficient of the composites at room temperature were examined in a ball-on-surface apparatus under dry conditions. The worn surfaces and debris were studied by scanning electron microscopy. The final values of the friction coefficient were 0.9 and 0.8 for the Cr-25%Al2O3 and Cr-40%Al2O3 composites, respectively. Alloying Cr matrix with Re improved wear resistance of composite but, at the same time, it caused an increase in its coefficient of friction.

  14. The equilibrium liquidus temperatures of rhenium-carbon, platinum-carbon and cobalt-carbon eutectic alloys

    NASA Astrophysics Data System (ADS)

    Lowe, D. H.; Todd, A. D. W.; Van den Bossche, R.; Bloembergen, P.; Anhalt, K.; Ballico, M.; Bourson, F.; Briaudeau, S.; Campos, J.; Cox, M. G.; del Campo, D.; Dury, M. R.; Gavrilov, V.; Grigoryeva, I.; Hernanz, M. L.; Jahan, F.; Khlevnoy, B.; Khromchenko, V.; Lu, X.; Machin, G.; Mantilla, J. M.; Martin, M. J.; McEvoy, H. C.; Rougié, B.; Sadli, M.; Salim, S. G. R.; Sasajima, N.; Taubert, D. R.; van der Ham, E.; Wang, T.; Wei, D.; Whittam, A.; Wilthan, B.; Woods, D. J.; Woodward, J. T.; Woolliams, E. R.; Yamada, Y.; Yamaguchi, Y.; Yoon, H. W.; Yuan, Z.

    2017-06-01

    The eutectic alloys rhenium-carbon, platinum-carbon and cobalt-carbon have been proposed as reference standards for thermometry, with temperature and uncertainty values specified within the mise en pratique of the definition of the kelvin. These alloys have been investigated in a collaboration of eleven national measurement institutes and laboratories. Published results reported the point-of-inflection in the melting curve with extremely low uncertainties. However, to be considered as standards it is necessary to stipulate what phenomenon a temperature value has been ascribed to; specifically, this should be a thermodynamic state. Therefore, the data have been further evaluated and the equilibrium liquidus temperatures determined based on a consideration of limits and assuming a rectangular probability distribution. The values are: for rhenium-carbon 2747.91  ±  0.44 K, for platinum-carbon 2011.50  ±  0.22 K and for cobalt-carbon 1597.48  ±  0.14 K, with uncertainties at approximately a 95% coverage probability. It is proposed that these values could be used as the basis of thermodynamic temperature measurement at high temperatures (above 1300 K).

  15. Redox induced electron transfer in doublet azo-anion diradical rhenium(II) complexes. Characterization of complete electron transfer series.

    PubMed

    Paul, Nandadulal; Samanta, Subhas; Goswami, Sreebrata

    2010-03-15

    Reactions of dirhenium decacarbonyl with the two azoaromatic ligands, L(a) = (2-phenylazo)pyridine and L(b) = (4-chloro-2-phenylazo)pyridine (general abbreviation of the ligands is L) afford paramagnetic rhenium(II) complexes, [Re(II)(L(*-))(2)(CO)(2)] (1) (S = 1/2 ground state) with two one-electron reduced azo-anion radical ligands in an octahedral geometrical arrangement. At room temperature (300 K) the complexes 1a-b, showed magnetic moments (mu(eff)) close to 1.94 mu(B), which is suggestive of the existence of strong antiferromagnetic interactions in the complexes. The results of magnetic measurements on one of the complexes, 1b, in the temperature range 2-300 K are reported. The above complexes showed two cathodic and two anodic responses in cyclic voltammetry where one-electron oxidation leads to an unusual redox event involving simultaneous reduction of the rhenium(II) and oxidation of the second ligand via intramolecular electron transfer. The oxidized complexes 1a(+) and 1b(+) are air stable and were isolated as crystalline solids as their tri-iodide (I(3)(-)) salts. The structures of the two representative complexes, 1b and [1b]I(3), as determined by X-ray crystallography, are compared. The anionic complexes, [1](-) and [1](2-) were characterized in solution by their spectral properties.

  16. XANES and EXAFS studies on the Rhenium L absorption edges of graphite intercalation compounds of ReCl 5

    NASA Astrophysics Data System (ADS)

    Fröba, M.; Lochte, K.; Metz, W.

    1995-02-01

    X-ray absorption measurements were carried out at the ReL II,III absorption edges of graphite intercalation compounds (GICs) of ReCl 5 and a series of different rhenium chlorides. The EXAFS analysis of the Re L III edges yields a coordination number of six and an average ReCl bond length of 234.6 pm for the GICs. This distance as well as the energy shift of the white lines indicate an oxidation state of 4-4.5 for rhenium in its GICs. The analysis of the white lines always reveals larger widths for the L III as compared to the L II edges. The white lines of the pure metal chlorides in the series +3, +4 and +5 for the oxidation state of Re are shifted to higher energies accompanied by an increase of the intensities. The GICs exhibit the same dependence between energy position and oxidation state, but the intensities are always higher.

  17. Rhenium and technetium tricarbonyl, {M(CO)3} (+) (M = Tc, Re), binding to mammalian metallothioneins: new insights into chemical and radiopharmaceutical implications.

    PubMed

    Lecina, Joan; Palacios, Òscar; Atrian, Sílvia; Capdevila, Mercè; Suades, Joan

    2015-04-01

    This paper deals with the binding of the four mammalian metallothioneins (MTs) to the organometallic metal fragment {fac-M(CO)3}(+) (M = (99)Tc, Re), which is highly promising for the preparation of second-generation radiopharmaceuticals. The study of the transmetallation reaction between zinc and rhenium in Zn7-MT1 by means of UV-vis and CD spectroscopy demonstrated the incorporation of the {fac-Re(CO)3}(+) fragment to the MTs. This reaction should be performed at 70 °C to accelerate the reaction rate, a result that is consistent with the reported reactivity of the rhenium fragment. ESI-TOF MS demonstrated the formation of mixed-metal species as Zn6,{Re(CO)3}-MT, Zn6,{Re(CO)3}2-MT, and Zn5,{Re(CO)3}3-MT, as well as the different reactivity of the four MT isoforms. Hence, Zn-MT3 showed the highest reactivity, in agreement with its high Cu-thionein character, whereas Zn-MT2 exhibited the lowest reactivity, in line with its high Zn-thionein character. The reactivity of the Zn-loaded forms of MT1 and MT4 is intermediate between those of MT3 and MT2. The study of the binding of the {fac-(99)Tc(CO)3}(+) fragment to MTs showed a significant and very interesting different reactivity in relation to rhenium. The transmetallation reaction is much more effective with technetium than with rhenium and significant amounts of mixed Zn x ,{(99)Tc(CO)3} y -MT species were formed with the four MT isoforms whereas only MT3 rendered similar amounts of rhenium derivatives. The results obtained in this study support the possible use of technetium for labelling mammalian metallothioneins and also for possible radiopharmaceutical applications.

  18. Combination of three metals for the treatment of cancer: gallium, rhenium and platinum. 1. Determination of the optimal schedule of treatment.

    PubMed

    Collery, Philippe; Mohsen, Ahmed; Kermagoret, Anthony; D'Angelo, Jean; Morgant, Georges; Desmaele, Didier; Tomas, Alain; Collery, Thomas; Wei, Ming; Badawi, Abdelfattah

    2012-07-01

    Platinum is well known for its anticancer activity, firstly used as cis-diaminedichloroplatinum (II) (CDDP), with a wide range of activity. Its main mechanism of action involves its binding to DNA. Gallium, another metal, has also demonstrated apoptotic effects on malignant cells, but through interaction with targets other than DNA, such as the membrane, cytoskeleton and proteasome, and on enzyme activities. An antitumor synergism between CDDP and both gallium and rhenium compounds has been demonstrated. For these reasons, we proposed to combine these three metals and to determine at which doses each compound could be administered without major toxicity. CDDP, tetrakis(1-octanol) tris(5-aminosalicylate)gallium(III), and a diseleno-ether rhenium(I) complex were used in this experimental study in breast cancer MCF-7 tumor-bearing mice. CDDP was administered intraperitoneally (i.p.) twice a week at the dose of 3 mg/kg. Tetrakis(1-octanol) tris(5-aminosalicylate) gallium (III) and rhenium(I) diseleno-ether complexes were administered orally, daily, five days a week for three weeks, at doses ranging from 20 to 100 mg/kg for the gallium compound and from 10 to 50 mg/kg for the rhenium compound. Doses of 10 mg/kg of rhenium(I) diseleno-ether, and 100 mg/kg of the salicylate gallium compound, in combination with CDDP induced a significant decrease of 50% of the tumor volume, by comparison with the control group. In contrast, the decrease of the tumor volume in mice treated by CDDP alone was less than 25%. Changes in the sequence of administration of the three metals will be discussed to improve the therapeutic index.

  19. Synthesis and reactivity of tris(imido)rhenium complexes containing rhenium-main group element bonds. silicon-carbon bond activations of PhSiH(3) by silyl complexes.

    PubMed

    Gavenonis, John; Tilley, T Don

    2004-07-12

    The synthesis and reactivity of a series of complexes of the (DippN=)(3)Re (Dipp = 2,6-(i)Pr(2)C(6)H(3)) fragment are reported. The anionic, Re(V) complex (THF)(2)Li(micro,micro-NDipp)(2)Re(=NDipp) (1), prepared by the reaction of (DippN=)(3)ReCl with (THF)(3)LiSi(SiMe(3))(3) or (t)BuLi (2 equiv) in the presence of THF (4 equiv), served as an important starting material for the synthesis of rhenium-element-bonded complexes. For example, treatment of 1 with ClSiR(3) gave the corresponding silyl complexes (DippN=)(3)ReSiR(3) (SiR(3) = SiMe(3) (2a), SiHPh(2) (2b), SiH(2)Ph (2c)). Complexes 2a-c are thought to exist in equilibrium between the Re(VII) (DippN=)(3)ReSiR(3) and Re(V) (DippN=)(2)ReN(SiR(3))Dipp isomers. Complexes 2a,b reacted with PhSiH(3) to give reaction mixtures that included 2c, Ph(2)SiH(2), SiH(4), and C(6)H(6). The silane and organic products arise from Si-C bond formation and cleavage. Treatment of 2a with CO gave (DippN=)(2)Re[N(SiMe(3))Dipp](CO) (3), which appears to result from trapping of the reactive Re(V) isomer of 2a by CO. Complex 1 reacted with the main group halides MeI, Ph(3)GeCl, Me(3)SnCl, Ph(2)PCl, and PhSeCl to give the corresponding rhenium complexes (DippN=)(3)ReER(n) (ER(n)() = Me (4), GePh(3) (5), SnMe(3) (6), PPh(2) (7), SePh (8)) in high yields. X-ray diffraction data for 5 indicate that the germyl ligand is bonded to rhenium, but positional disorder of the phenyl and Dipp groups prevented refinement of accurate metric parameters.

  20. Rhenium and manganese bipyridine tricarbonyl catalysts for the electrochemical reduction of carbon dioxide

    NASA Astrophysics Data System (ADS)

    Sampson, Matthew Dean

    Electrocatalytic reduction of carbon dioxide (CO2) is a profoundly challenging problem that is of interest, not only as a means of counteracting unsustainable emissions of CO2, but also as a method for the development of renewable fuels. Rhenium and manganese bipyridine tricarbonyl complexes are among the most active and robust catalysts for proton-coupled CO 2 reduction to carbon monoxide (CO). X- ray Absorption Spectroscopy studies are reported to reveal the electronic ground state of the Re catalysts, which help explain origins for high selectivity for CO2 reduction over proton reduction. Stopped-flow mixing in tandem with rapid-scan IR spectroscopy is utilized to probe the direct reaction of the Re catalysts with CO 2, observing, for the first time, the binding of CO2 to these catalysts. Manganese bipyridine catalysts are desirable, in comparison with their Re analogs, due to the earth-abundance of Mn and the ability for these catalysts to operate at lower overpotentials. One distinct difference between these Mn catalysts and their Re counterparts is a high tendency for dimerization after one-electron reduction, which contributes to the potential necessary to access their active state and to limiting their catalytic activity. Synthetic modification of the bipyridine ligand (by adding bulky mesityl groups) is used to completely eliminate dimerization for these Mn complexes, allowing the active catalyst to be generated at a 300 mV more positive potential than in typically Mn bipyridine complexes. CO2 reactivities in the presence of weak Bronsted acids, strong Bronsted acids, and Lewis acids have been explored in order to encourage this bulky Mn catalyst to reduce CO2 at low overpotentials. Mechanistic tools, including IR-spectroelectrochemistry, are described to gain insight into these unique catalytic processes. In order to further enhance stability and facilitate product separation, the use of metal-organic frameworks (MOFs) is explored as a means of anchoring

  1. Rhenium-186 liposomes as convection-enhanced nanoparticle brachytherapy for treatment of glioblastoma

    PubMed Central

    Phillips, William T.; Goins, Beth; Bao, Ande; Vargas, Daniel; Guttierez, Juan E.; Trevino, Abram; Miller, Jessica R.; Henry, James; Zuniga, Richard; Vecil, Giacomo; Brenner, Andrew J.

    2012-01-01

    Although external beam radiation is an essential component to the current standard treatment of primary brain tumors, its application is limited by toxicity at doses more than80 Gy. Recent studies have suggested that brachytherapy with liposomally encapsulated radionuclides may be of benefit, and we have reported methods to markedly increase the specific activity of rhenium-186 (186Re)–liposomes. To better characterize the potential delivery, toxicity, and efficacy of the highly specific activity of 186Re-liposomes, we evaluated their intracranial application by convection-enhanced delivery in an orthotopic U87 glioma rat model. After establishing an optimal volume of 25 µL, we observed focal activity confined to the site of injection over a 96-hour period. Doses of up to 1850 Gy were administered without overt clinical or microscopic evidence of toxicity. Animals treated with 186Re-liposomes had a median survival of 126 days (95% confidence interval [CI], 78.4–173 days), compared with 49 days (95% CI, 44–53 days) for controls. Log-rank analysis between these 2 groups was highly significant (P = .0013) and was even higher when 100 Gy was used as a cutoff (P < .0001). Noninvasive luciferase imaging as a surrogate for tumor volume showed a statistically significant separation in bioluminescence by 11 days after 100 Gy or less treatment between the experimental group and the control animals (χ2[1, N= 19] = 4.8; P = .029). MRI also supported this difference in tumor size. Duplication of tumor volume differences and survival benefit was possible in a more invasive U251 orthotopic model, with clear separation in bioluminescence at 6 days after treatment (χ2[1, N= 9] = 4.7; P = .029); median survival in treated animals was not reached at 120 days because lack of mortality, and log-rank analysis of survival was highly significant (P = .0057). Analysis of tumors by histology revealed minimal areas of necrosis and gliosis. These results support the potential

  2. Online Rhenium Fractionation Correction Using Tungsten-Doping Technique on a Magnetic Sector ICP-MS.

    NASA Astrophysics Data System (ADS)

    Poirier, A.

    2001-12-01

    Precise Re concentrations are commonly analysed by ID-NTIMS. The use of multicollector ICP-MS may alternatively be more time effective for similar precisions. One major drawback with ICP-MS is the lack of control concerning instrumental mass bias, which tends to be time dependant for a given machine setting. The mass discrimination in the ICP-MS is a sum of numerous phenomena, mainly the space charge effects within the plasma, the supersonic gaseous expansion between the cones, and the fractionation related to the hexapole , in the case of the IsoProbe (Micromass' ICP-MS). Rhenium possesses only two isotopes, so an internal fractionation correction is not possible -at least for spiked samples. A standard bracketing technique would be efficient to resolve this problem if the fractionation effects were evolving regularly with time; we have evidence that it is not always the case for our instrument. Similarly to the Pb-Tl systematics, we added some W to a Re standard solution. These two elements are neighbours in the Mendeleiev table and do not have any isobars. This allows us to measure 184W, 185Re, 186W and 187Re simultaneously (static mode, 188Os is also monitored) and compare the 186W/184W and 187Re/185Re. Repeated analyses of this mixture yielded different fractionation factors ( that is the beta value from the exponential law, normalised to 187Re/185Re=1.67398, Gramlich et al, 1973 and 186W/184W=0.927633, Lee and Halliday, 1995) for these two metals. However these beta values evolve together with time. The relationship between the beta-Re and beta-W is linear, with a slope of one and a non-zero intercept within instrumental precision. The slope indicates that these elements behave similarly in the ICP-MS. The intercept is most likely a result of inconsistent normalising values for the measured ratios : the Re reference value currently used may have to be reconsidered. In conclusion, empirical results allow to calculate an accurate "on-line" fractionation factor

  3. Rhenium-186 liposomes as convection-enhanced nanoparticle brachytherapy for treatment of glioblastoma.

    PubMed

    Phillips, William T; Goins, Beth; Bao, Ande; Vargas, Daniel; Guttierez, Juan E; Trevino, Abram; Miller, Jessica R; Henry, James; Zuniga, Richard; Vecil, Giacomo; Brenner, Andrew J

    2012-04-01

    Although external beam radiation is an essential component to the current standard treatment of primary brain tumors, its application is limited by toxicity at doses more than 80 Gy. Recent studies have suggested that brachytherapy with liposomally encapsulated radionuclides may be of benefit, and we have reported methods to markedly increase the specific activity of rhenium-186 ((186)Re)-liposomes. To better characterize the potential delivery, toxicity, and efficacy of the highly specific activity of (186)Re-liposomes, we evaluated their intracranial application by convection-enhanced delivery in an orthotopic U87 glioma rat model. After establishing an optimal volume of 25 µL, we observed focal activity confined to the site of injection over a 96-hour period. Doses of up to 1850 Gy were administered without overt clinical or microscopic evidence of toxicity. Animals treated with (186)Re-liposomes had a median survival of 126 days (95% confidence interval [CI], 78.4-173 days), compared with 49 days (95% CI, 44-53 days) for controls. Log-rank analysis between these 2 groups was highly significant (P = .0013) and was even higher when 100 Gy was used as a cutoff (P < .0001). Noninvasive luciferase imaging as a surrogate for tumor volume showed a statistically significant separation in bioluminescence by 11 days after 100 Gy or less treatment between the experimental group and the control animals (χ(2)[1, N= 19] = 4.8; P = .029). MRI also supported this difference in tumor size. Duplication of tumor volume differences and survival benefit was possible in a more invasive U251 orthotopic model, with clear separation in bioluminescence at 6 days after treatment (χ(2)[1, N= 9] = 4.7; P = .029); median survival in treated animals was not reached at 120 days because lack of mortality, and log-rank analysis of survival was highly significant (P = .0057). Analysis of tumors by histology revealed minimal areas of necrosis and gliosis. These results support the potential

  4. Exposure data from multi-application, multi-industry maintenance of surfaces and joints sealed with asbestos-containing gaskets and packing.

    PubMed

    Boelter, Fred; Simmons, Catherine; Hewett, Paul

    2011-04-01

    Fluid sealing devices (gaskets and packing) containing asbestos are manufactured and blended with binders such that the asbestos fibers are locked in a matrix that limits the potential for fiber release. Occasionally, fluid sealing devices fail and need to be replaced or are removed during preventive maintenance activities. This is the first study known to pool over a decade's worth of exposure assessments involving fluid sealing devices used in a variety of applications. Twenty-one assessments of work activities and air monitoring were performed under conditions with no mechanical ventilation and work scenarios described as "worst-case" conditions. Frequently, the work was conducted using aggressive techniques, along with dry removal practices. Personal and area samples were collected and analyzed in accordance with the National Institute for Occupational Safety and Health Methods 7400 and 7402. A total of 782 samples were analyzed by phase contrast microscopy, and 499 samples were analyzed by transmission electron microscopy. The statistical data analysis focused on the overall data sets which were personal full-shift time-weighted average (TWA) exposures, personal 30-min exposures, and area full-shift TWA values. Each data set contains three estimates of exposure: (1) total fibers; (2) asbestos fibers only but substituting a value of 0.0035 f/cc for censored data; and (3) asbestos fibers only but substituting the limit of quantification value for censored data. Censored data in the various data sets ranged from 7% to just over 95%. Because all the data sets were censored, the geometric mean and geometric standard deviation were estimated using the maximum likelihood estimation method. Nonparametric, Kaplan-Meier, and lognormal statistics were applied and found to be consistent and reinforcing. All three sets of statistics suggest that the mean and median exposures were less than 25% of 0.1 f/cc 8-hr TWA sample or 1.0 f/cc 30-min samples, and that there is at

  5. COATING METHOD

    DOEpatents

    Townsend, R.G.

    1959-08-25

    A method is described for protectively coating beryllium metal by etching the metal in an acid bath, immersing the etched beryllium in a solution of sodium zincate for a brief period of time, immersing the beryllium in concentrated nitric acid, immersing the beryhlium in a second solution of sodium zincate, electroplating a thin layer of copper over the beryllium, and finally electroplating a layer of chromium over the copper layer.

  6. Contribution of electrospray mass spectrometry for the characterization, design, and development of nitrido technetium and rhenium heterocomplexes as potential radiopharmaceuticals.

    PubMed

    Tisato, Francesco; Bolzati, Cristina; Porchia, Marina; Refosco, Fiorenzo

    2004-01-01

    Diagnostic nuclear medicine (NM) is among the imaging procedures (together with X-ray, computerized tomography, magnetic resonance, and echography) the clinicians can routinely adopt to image organs or tissues and related disorders. (99m)Tc-based agents are the radiopharmaceuticals of election in diagnostic NM because of the ideal physical properties of the 99mTc nuclide (t1/2 6.01 hr; Egamma 142 keV), low cost, and easy availability through the commercial 99Mo/99mTc generator, and chemical versatility of the element. In the last two decades the synergistic work of clinics, pharmacologists, and coordination chemists has had a tremendous impact in the development of new 99mTc-based radiopharmaceuticals through the recognition of the structure at the molecular level of the agent utilized. This has been achieved by studying the physico-chemical properties of the long-lived 99gTc (t1/2 2.11 x 10(5) year; Ebeta 292 keV) and third-row congener Re isostructural compounds. Electrospray ionization mass spectrometry (ESI-MS) and collision experiments (MS/MS) represent valuable analytical techniques suitable for the characterization of both technetium and rhenium complexes relevant to NM. Unequivocal structural identification of these bioinorganic compounds, either simple coordination complexes ("essential radiopharmaceuticals") or more sophisticated structures carrying bioactive fragments ("receptor-specific" radiopharmaceuticals), can be realized in combination with multinuclear NMR spectroscopy. MS/MS experiments provide useful information on the different metal-ligand bond strength, and comparison of the fragmentation profiles of isostructural technetium and rhenium compounds give additional details on the role played by the metal in determining preferred decomposition channels. The analysis of these data contribute to design novel synthetic strategies for the obtainment of technetium and rhenium compounds relevant to NM. The chemistry underlying the production of a new

  7. Solid-state thermolysis of a fac-rhenium(I) carbonyl complex with a redox non-innocent pincer ligand.

    PubMed

    Jurca, Titel; Chen, Wen-Ching; Michel, Sheila; Korobkov, Ilia; Ong, Tiow-Gan; Richeson, Darrin S

    2013-03-25

    The development of rhenium(I) chemistry has been restricted by the limited structural and electronic variability of the common pseudo-octahedral products fac-[ReX(CO)3L2] (L2 = α-diimine). We address this constraint by first preparing the bidentate bis(imino)pyridine complexes [(2,6-{2,6-Me2C6H3N=CPh}2C5H3N)Re(CO)3X] (X = Cl 2, Br 3), which were characterized by spectroscopic and X-ray crystallographic means, and then converting these species into tridentate pincer ligand compounds, [(2,6-{2,6-Me2C6H3N=CPh}2C5H3N)Re(CO)2X] (X = Cl 4, Br 5). This transformation was performed in the solid-state by controlled heating of 2 or 3 above 200 °C in a tube furnace under a flow of nitrogen gas, giving excellent yields (≥95 %). Compounds 4 and 5 define a new coordination environment for rhenium(I) carbonyl chemistry where the metal center is supported by a planar, tridentate pincer-coordinated bis(imino)pyridine ligand. The basic photophysical features of these compounds show significant elaboration in both number and intensity of the d-π* transitions observed in the UV/Vis spec tra relative to the bidentate starting materials, and these spectra were analyzed using time-dependent DFT computations. The redox nature of the bis(imino)pyridine ligand in compounds 2 and 4 was examined by electrochemical analysis, which showed two ligand reduction events and demonstrated that the ligand reduction shifts to a more positive potential when going from bidentate 2 to tridentate 4 (+160 mV for the first reduction step and +90 mV for the second). These observations indicate an increase in electrostatic stabilization of the reduced ligand in the tridentate conformation. Elaboration on this synthetic methodology documented its generality through the preparation of the pseudo-octahedral rhenium(I) triflate complex [(2,6-{2,6-Me2C6H3N=CPh}2C5H3N)Re(CO)2OTf] (7, 93 % yield). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Thermal radiative properties: Coatings.

    NASA Technical Reports Server (NTRS)

    Touloukian, Y. S.; Dewitt, D. P.; Hernicz, R. S.

    1972-01-01

    This volume consists, for the most part, of a presentation of numerical data compiled over the years in a most comprehensive manner on coatings for all applications, in particular, thermal control. After a moderately detailed discussion of the theoretical nature of the thermal radiative properties of coatings, together with an overview of predictive procedures and recognized experimental techniques, extensive numerical data on the thermal radiative properties of pigmented, contact, and conversion coatings are presented. These data cover metallic and nonmetallic pigmented coatings, enamels, metallic and nonmetallic contact coatings, antireflection coatings, resin coatings, metallic black coatings, and anodized and oxidized conversion coatings.

  9. A surface site as polydentate ligand of a metal complex: Density functional studies of rhenium subcarbonyls supported on magnesium oxide

    SciTech Connect

    Hu, A.; Neyman, K.M.; Staufer, M.; Belling, T.; Gates, B.C.; Roesch, N.

    1999-05-12

    Notwithstanding the importance of supported organometallic species as industrial catalysts, most are nonuniform mixtures, with only a few being well-characterized at the atomic level. Rhenium subcarbonyls on MgO, in contrast, consist of nearly uniform surface species and are among the best-studied organometallic complexes on oxides. EXAFS and infrared spectra showed that decomposition of the precursors [HRe(CO){sub 5}], [H{sub 3}Re{sub 3}(CO){sub 12}], and [Re{sub 2}(CO){sub 10}] on MgO powder results in fragments, assigned as Re(CO){sub 3}{sup n+}, coordinated to surface ligands. The concept of a surface site as a polydentate ligand evokes the remarkable circumstance in which the adsorbate-substrate bonds are as strong as metal-ligand bonds in common transition metal complexes, as shown by the present investigation.

  10. The Role of Rhenium on the Temporal Evolution of the Nanostructure of a Model Ni-Al-Cr-Re Superalloy

    NASA Technical Reports Server (NTRS)

    Yoon, Kevin E.; Noebe, Ronald D.; Seidman, David N.

    2004-01-01

    Rhenium (2 at.%) additions to a model Ni-8.5 at.% Cr-10 at.% Al alloy are studied with respect to its effects on the temporal evolution of the nanostructure and the partitioning behavior of the four elements between the gamma (fcc) and gamma' (L1(sub 2)) phases. Chemical evolution of this quaternary alloy aged at 1073 K from 0.25 to 264 h, is investigated by three-dimensional atom-probe (3DAP) microscopy. The morphology of gamma'-precipitates remains spheroidal, even at an aging time of 264 h. The results demonstrate that Re slows the coarsening of gamma'-precipitates, in comparison to the ternary Ni-10 at.% A1-8.5 at.% Cr alloy at 1073 K.

  11. Two-electron carbon dioxide reduction catalyzed by rhenium(I) bis(imino)acenaphthene carbonyl complexes.

    PubMed

    Portenkirchner, Engelbert; Kianfar, Elham; Sariciftci, Niyazi Serdar; Knör, Günther

    2014-05-01

    Rhenium(I) carbonyl complexes carrying substituted bis(arylimino)acenaphthene ligands (BIAN-R) have been tested as potential catalysts for the two-electron reduction of carbon dioxide. Cyclic voltammetric studies as well as controlled potential electrolysis experiments were performed using CO2-saturated solutions of the complexes in acetonitrile and acetonitrile-water mixtures. Faradaic efficiencies of more than 30 % have been determined for the electrocatalytic production of CO. The effects of ligand substitution patterns and water content of the reaction medium on the catalytic performance of the new catalysts are discussed. © 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

  12. Synthesis, characterization and cellular location of cytotoxic constitutional organometallic isomers of rhenium delivered on a cyanocobalmin scaffold.

    PubMed

    Santoro, Giuseppe; Zlateva, Theodora; Ruggi, Albert; Quaroni, Luca; Zobi, Fabio

    2015-04-21

    Constitutional isomers of cyanocobalamin adducts based on a fluorescent rhenium tris-carbonyl diimine complex were prepared, characterized and tested against PC-3 cancer cells. The adducts differ only in the relative binding position of the organometallic species which is either bound at the cyano or the 5'-hydroxo group of vitamin B12. When tested for their cytotoxic potency, the species showed IC50 values in the low μM rage. Upon conjugation to the vitamin an energy transfer process causes an extremely low quantum yield of fluorescence emission, making the conjugates unsuitable for fluorescence imaging. However, by exploiting the vibrational signature of the fac-[Re(CO)3](+) core, their cellular distribution was evaluated via FTIR spectromicroscopy.

  13. Synthesis, characterization and binding affinities of rhenium(I) thiosemicarbazone complexes for the estrogen receptor (α/β).

    PubMed

    Núñez-Montenegro, Ara; Carballo, Rosa; Vázquez-López, Ezequiel M

    2014-11-01

    The binding affinities towards estrogen receptors (ERs) α and β of a set of thiosemicarbazone ligands (HL(n)) and their rhenium(I) carbonyl complexes [ReX(HL(n))(CO)3] (X=Cl, Br) were determined by a competitive standard radiometric assay with [(3)H]-estradiol. The ability of the coordinated thiosemicarbazone ligands to undergo deprotonation and the lability of the ReX bond were used as a synthetic strategy to obtain [Re(hpy)(L(n))(CO)3] (hpy=3- or 4-hydroxypyridine). The inclusion of the additional hpy ligand endows the new thiosemicarbazonate complexes with an improved affinity towards the estrogen receptors and, consequently, the values of the inhibition constant (Ki) could be determined for some of them. In general, the values of Ki for both ER subtypes suggest an appreciable selectivity towards ERα. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Rhenium hydride/boron Lewis acid cocatalysis of alkene hydrogenations: activities comparable to those of precious metal systems.

    PubMed

    Jiang, Yanfeng; Hess, Jeannine; Fox, Thomas; Berke, Heinz

    2010-12-29

    Dibromonitrosyl(dihydrogen)rhenium(I) complexes [ReBr(2)(NO)(PR(3))(2)(η(2)-H(2))] (1; R = iPr, a; Cy, b) and Me(2)NH·BH(3) (DMAB) catalyze at either 90 °C or ambient temperature under 10 bar of H(2) the hydrogenation of various terminal and cyclic alkenes (1-hexene, 1-octene, cyclooctene, styrene, 1,5-cyclooctadiene, 1,7-octadiene, α-methylstyrene). Maximum turnover frequency (TOF) values of 3.6 × 10(4) h(-1) at 90 °C and 1.7 × 10(4) h(-1) at 23 °C were achieved in the hydrogenation of 1-hexene. The extraordinary catalytic performance of the 1/DMAB system is attributed to the formation of five-coordinate rhenium(I) hydride complexes [Re(Br)(H)(NO)(PR(3))(2)] (2; R = iPr, a; Cy, b) and the action of the Lewis acid BH(3) originating from DMAB. The related 2/BH(3)·THF catalytic system also exhibits under the same conditions high activity in the hydrogenation of various alkenes with a maximum turnover number (TON) of 1.2 × 10(4) and a maximum TOF of 4.0 × 10(4) h(-1). For the hydrogenations of 1-hexene with 2a and 2b, the effect of the strength of the boron Lewis acid was studied, the acidity being in the following order: BCl(3) > BH(3) > BEt(3) ≈ BF(3) > B(C(6)F(5))(3) > BPh(3) ≫ B(OMe)(3). The order in catalytic activity was found to be B(C(6)F(5))(3) > BEt(3) ≈ BH(3)·THF > BPh(3) ≫ BF(3)·OEt(2) > B(OMe)(3) ≫ BCl(3). The stability of the catalytic systems was checked via TON vs time plots, which revealed the boron Lewis acids to cause an approximate inverse order with the Lewis acid strength: BPh(3) > BEt(3) ≈ BH(3)·THF > B(C(6)F(5))(3). For the 2a/BPh(3) system a maximum TON of 3.1 × 10(4) and for the 2a/B(C(6)F(5))(3) system a maximum TOF of 5.6 × 10(4) h(-1) were obtained in the hydrogenation of 1-hexene. On the basis of kinetic isotope effect determinations, H(2)/D(2) scrambling, halide exchange experiments, Lewis acid variations, and isomerization of terminal alkenes, an Osborn-type catalytic cycle is proposed with olefin before H(2

  15. Stereochemical studies in the development of technetium radiopharmaceuticals. 1. Fluxional racemization of technetium and rhenium penicillamine complexes

    SciTech Connect

    Johnson, D.L.; Fritzberg, A.R.; Hawkins, B.L.; Kasina, S.; Eshima, D.

    1984-12-05

    Rhenium and technetium penicillamine complexes have been synthesized by SnCl/sub 2/ reduction of ReO/sub 4//sup -/ or TcO/sub 4//sup -/ in the presence of optically pure or racemic penicillamine. The complexes are characterized by their chromatographic behavior, electronic spectra, fast atom bombardment mass spectra, and variable temperature /sup 1/H NMR spectra. All complexes are six-coordinate in solution, with one tridentate penicillamine, one bidentate penicillamine, and one oxo ligand. The mixed complexes are functional, racemizing by exchange of carboxylates at the sites trans to the oxo ligand. Kinetics of this process were measured by complete line-shape analysis of the NMR spectra, and values for reaction rate constants are reported.

  16. New metallic quasi-two-dimensional structures of graphene and molybdenum disulfide layers with embedded rhenium atoms

    NASA Astrophysics Data System (ADS)

    Demin, V. A.; Chernozatonskii, L. A.

    2015-01-01

    New metallic structures in the system of graphene and molybdenum disulfide layers with embedded rhenium atoms, in which the graphene layer is rotated by 30° to the molybdenum disulfide layer and the Re atom either substitutes the molybdenum atom in the MoS2 layer or is located between the layers mainly interacting with three sulfur atoms and six carbon atoms, are examined. In the latter case, a high electron density of states has been found in the Fermi level, which indicates a high metallicity of the graphene30°-(Re)-MoS2 bilayer in comparison with other bilayer structures considered earlier. All proposed structures are energetically stable. Possible applications of the studied bilayers have been considered as well.

  17. The optical sensor fac-tricarbonylchloro(di-2-pyridylmethanone p-nitrophenylhydrazone)rhenium(I) dimethyl sulfoxide solvate.

    PubMed

    Bakir, M

    2001-12-01

    The first metal complex of di-2-pyridylmethanone p-nitrophenylhydrazone (dpknph), i.e. the title compound, fac-[ReCl(C17H13N5O2)(CO)3]*C2H6OS, crystallizes as well separated pseudo-tetrahedral DMSO (DMSO is dimethyl sulfoxide) and pseudo-octahedral fac-[ReCl(dpknph)(CO)3] moieties. Two N atoms from dpknph, three C atoms from the carbonyl groups and one chloride ion occupy the coordination sphere around rhenium. The coordinated dpknph ligand forms a six-membered ring in a boat conformation, with the pyridine rings in a butterfly formation. The p-nitrophenylhydrazone moiety is planar, with all C and N atoms in sp2-hybridized forms. The molecules pack as stacks of interlocked fac-[ReCl(dpknph)(CO)3]*DMSO units via a network of non-covalent bonds that include solute-solute, solvent-solute and pi-pi interactions.

  18. Rhenium(I) polypyridine diamine complexes as intracellular phosphorogenic sensors: synthesis, characterization, emissive behavior, biological properties, and nitric oxide sensing.

    PubMed

    Choi, Alex Wing-Tat; Yim, Vicki Man-Wai; Liu, Hua-Wei; Lo, Kenneth Kam-Wing

    2014-07-28

    We report the development of a series of rhenium(I) polypyridine complexes appended with an electron-rich diaminoaromatic moiety as phosphorogenic sensors for nitric oxide (NO). The diamine complexes [Re(N^N)(CO)3 (py-DA)][PF6 ] (py-DA=3-(N-(2-amino-5-methoxyphenyl)aminomethyl)pyridine; N^N=1,10-phenanthroline (phen) (1 a), 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4 -phen) (2 a), 4,7-diphenyl-1,10-phenanthroline (Ph2 -phen) (3 a)) have been synthesized and characterized. In contrast to common rhenium(I) diimines, these diamine complexes were very weakly emissive due to quenching of the triplet metal-to-ligand charge-transfer ((3) MLCT) emission by the diaminoaromatic moiety through photoinduced electron transfer (PET). Upon treatment with NO, the complexes were converted into the triazole derivatives [Re(N^N)(CO)3 (py-triazole)][PF6 ] (py-triazole=3-((6-methoxybenzotriazol-1-yl)methyl)pyridine; N^N=phen (1 b), Me4 -phen (2 b), Ph2 -phen (3 b)), resulting in significant emission enhancement (I/I0 ≈60). The diamine complexes exhibited high reaction selectivity to NO, and their emission intensity was found to be independent on pH. Also, these complexes were effectively internalized by HeLa cells and RAW264.7 macrophages with negligible cytotoxicity. Additionally, the use of complex 3 a as an intracellular phosphorogenic sensor for NO has been demonstrated. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Identification of rhenium donors and sulfur vacancy acceptors in layered MoS{sub 2} bulk samples

    SciTech Connect

    Brandão, F. D. Ribeiro, G. M.; Vaz, P. H.; González, J. C.; Krambrock, K.

    2016-06-21

    MoS{sub 2} monolayers, a two-dimensional (2D) direct semiconductor material with an energy gap of 1.9 eV, offer many opportunities to be explored in different electronic devices. Defects often play dominant roles in the electronic and optical properties of semiconductor devices. However, little experimental information about intrinsic and extrinsic defects or impurities is available for this 2D system, and even for macroscopic 3D samples for which MoS{sub 2} shows an indirect bandgap of 1.3 eV. In this work, we evaluate the nature of impurities with unpaired spins using electron paramagnetic resonance (EPR) in different geological macroscopic samples. Regarding the fact that monolayers are mostly obtained from natural crystals, we expect that the majority of impurities found in macroscopic samples are also randomly present in MoS{sub 2} monolayers. By EPR at low temperatures, rhenium donors and sulfur vacancy acceptors are identified as the main impurities in bulk MoS{sub 2} with a corresponding donor concentration of about 10{sup 8–12} defects/cm{sup 2} for MoS{sub 2} monolayer. Electrical transport experiments as a function of temperature are in good agreement with the EPR results, revealing a shallow donor state with an ionization energy of 89 meV and a concentration of 7 × 10{sup 15 }cm{sup −3}, which we attribute to rhenium, as well as a second deeper donor state with ionization energy of 241 meV with high concentration of 2 × 10{sup 19 }cm{sup −3} and net acceptor concentration of 5 × 10{sup 18 }cm{sup −3} related to sulfur vacancies.

  20. Influence of donor-acceptor distance variation on photoinduced electron and proton transfer in rhenium(I)-phenol dyads.

    PubMed

    Kuss-Petermann, Martin; Wolf, Hilke; Stalke, Dietmar; Wenger, Oliver S

    2012-08-01

    A homologous series of four molecules in which a phenol unit is linked covalently to a rhenium(I) tricarbonyl diimine photooxidant via a variable number of p-xylene spacers (n = 0-3) was synthesized and investigated. The species with a single p-xylene spacer was structurally characterized to get some benchmark distances. Photoexcitation of the metal complex in the shortest dyad (n = 0) triggers release of the phenolic proton to the acetonitrile/water solvent mixture; a H/D kinetic isotope effect (KIE) of 2.0 ± 0.4 is associated with this process. Thus, the shortest dyad basically acts like a photoacid. The next two longer dyads (n = 1, 2) exhibit intramolecular photoinduced phenol-to-rhenium electron transfer in the rate-determining excited-state deactivation step, and there is no significant KIE in this case. For the dyad with n = 1, transient absorption spectroscopy provided evidence for release of the phenolic proton to the solvent upon oxidation of the phenol by intramolecular photoinduced electron transfer. Subsequent thermal charge recombination is associated with a H/D KIE of 3.6 ± 0.4 and therefore is likely to involve proton motion in the rate-determining reaction step. Thus, some of the longer dyads (n = 1, 2) exhibit photoinduced proton-coupled electron transfer (PCET), albeit in a stepwise (electron transfer followed by proton transfer) rather than concerted manner. Our study demonstrates that electronically strongly coupled donor-acceptor systems may exhibit significantly different photoinduced PCET chemistry than electronically weakly coupled donor-bridge-acceptor molecules.