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Sample records for dc resins

  1. Suppression of surface charge accumulation on Al2O3-filled epoxy resin insulator under dc voltage by direct fluorination

    NASA Astrophysics Data System (ADS)

    Zhang, Boya; Zhang, Guixin; Wang, Qiang; Li, Chuanyang; He, Jinliang; An, Zhenlian

    2015-12-01

    Surface charge accumulation on insulators under high dc voltage is a major factor that may lead to the reduction of insulation levels in gas insulated devices. In this paper, disc insulators made of Al2O3-filled epoxy resin were surface fluorinated using a F2/N2 mixture (12.5% F2) at 50 °C and 0.1 MPa for different durations of 15 min, 30 min and 60 min. A dc voltage was applied to the insulator for 30 min and the charge density on its surface was measured by an electrostatic probe. The results revealed significant lower surface charge densities on the fluorinated insulators in comparison with the original one. Surface conductivity measurements indicated a higher surface conductivity by over three orders of magnitude after fluorination, which would allow the charges to transfer along the surface and thus may suppress their accumulation. Further, attenuated total reflection infrared analysis and surface morphology observations of the samples revealed that the introduction of fluoride groups altered the surface physicochemical properties. These structure changes, especially the physical defects reduced the depth of charge traps in the surface layer, which was verified by the measurement of energy distributions of the electron and hole traps based on the isothermal current theory. The results in this paper demonstrate that fluorination can be a promising and effective method to suppress surface charge accumulation on epoxy insulators in gas insulated devices.

  2. Suppression of surface charge accumulation on Al{sub 2}O{sub 3}-filled epoxy resin insulator under dc voltage by direct fluorination

    SciTech Connect

    Zhang, Boya; Zhang, Guixin Li, Chuanyang; He, Jinliang; Wang, Qiang; An, Zhenlian

    2015-12-15

    Surface charge accumulation on insulators under high dc voltage is a major factor that may lead to the reduction of insulation levels in gas insulated devices. In this paper, disc insulators made of Al{sub 2}O{sub 3}-filled epoxy resin were surface fluorinated using a F{sub 2}/N{sub 2} mixture (12.5% F{sub 2}) at 50 °C and 0.1 MPa for different durations of 15 min, 30 min and 60 min. A dc voltage was applied to the insulator for 30 min and the charge density on its surface was measured by an electrostatic probe. The results revealed significant lower surface charge densities on the fluorinated insulators in comparison with the original one. Surface conductivity measurements indicated a higher surface conductivity by over three orders of magnitude after fluorination, which would allow the charges to transfer along the surface and thus may suppress their accumulation. Further, attenuated total reflection infrared analysis and surface morphology observations of the samples revealed that the introduction of fluoride groups altered the surface physicochemical properties. These structure changes, especially the physical defects reduced the depth of charge traps in the surface layer, which was verified by the measurement of energy distributions of the electron and hole traps based on the isothermal current theory. The results in this paper demonstrate that fluorination can be a promising and effective method to suppress surface charge accumulation on epoxy insulators in gas insulated devices.

  3. Milliwatt dc/dc Inverter

    NASA Technical Reports Server (NTRS)

    Mclyman, C. W.

    1983-01-01

    Compact dc/dc inverter uses single integrated-circuit package containing six inverter gates that generate and amplify 100-kHz square-wave switching signal. Square-wave switching inverts 10-volt local power to isolated voltage at another desired level. Relatively high operating frequency reduces size of filter capacitors required, resulting in small package unit.

  4. Simplified dc to dc converter

    NASA Technical Reports Server (NTRS)

    Gruber, R. P. (Inventor)

    1984-01-01

    A dc to dc converter which can start with a shorted output and which regulates output voltage and current is described. Voltage controlled switches directed current through the primary of a transformer the secondary of which includes virtual reactance. The switching frequency of the switches is appropriately varied to increase the voltage drop across the virtual reactance in the secondary winding to which there is connected a low impedance load. A starting circuit suitable for voltage switching devices is provided.

  5. DC to DC battery charger

    SciTech Connect

    Carr, F.L.; Terrill, L.R.

    1987-01-20

    A DC to DC battery charger is described for a vehicle comprising: adapter plug means for making electrical connections to a first battery through a cigarette lighter socket in the vehicle; means of making electrical connections to a second battery to be charged; a DC to AC converter and an AC to DC rectifier for elevating the voltage from the first battery to a voltage above that of the second battery; integrated circuit means for generating a pulse width modulated current as a function for the charged condition of the second battery; transistor switch means supplied with the pulse width modulated current for developing a charging voltage; a choke coil and a capacitor serially connected to the transistor switch means; and a diode connected across the choke coil and the capacitor whereby the capacitor is charged during pulses of current from the transistor switch means through the choke coil. The choke coil reverses polarity at the termination of the pulses of current and continues to charge the battery through the diode. The DC rectified voltage is controlled by the integrated circuit means for regulating current through the choke coil.

  6. Adaptable DC offset correction

    NASA Technical Reports Server (NTRS)

    Golusky, John M. (Inventor); Muldoon, Kelly P. (Inventor)

    2009-01-01

    Methods and systems for adaptable DC offset correction are provided. An exemplary adaptable DC offset correction system evaluates an incoming baseband signal to determine an appropriate DC offset removal scheme; removes a DC offset from the incoming baseband signal based on the appropriate DC offset scheme in response to the evaluated incoming baseband signal; and outputs a reduced DC baseband signal in response to the DC offset removed from the incoming baseband signal.

  7. Synthesis of fluorinated dimethacrylate monomer and its application in preparing Bis-GMA free dental resin.

    PubMed

    Yin, Mei; Guo, Sen; Liu, Fang; He, Jingwei

    2015-11-01

    With the aim to reduce human exposure to Bis-phenol A derivatives, a novel fluorinated dimethacrylate monomer FUDMA was synthesized and mixed with triethyleneglycol dimethacrylate (TEGDMA) to prepare 2,2-bis[4-(2-hydroxy-3-methacryloy- loxypropyl)phenyl]propane (Bis-GMA) free dental resin system. Physicochemical properties, such as double bond conversion (DC), polymerization shrinkage (VS), water sorption (WS) and solubility (SL), flexural strength (FS) and modulus (FM), and fracture energy of FUDMA/TEGDMA resin system were investigated. Bis-GMA/TEGDMA resin system was used as a control. The results showed that, compared with Bis-GMA/TEGDMA resin system, FUDMA/TEGDMA had advantages like higher DC, lower VS, and higher fracture energy, but had no disadvantages. Therefore, FUDMA/TEGDMA resin system had better comprehensive physicochemical properties than Bis-GMA/TEGDMA resin system, and FUDMA had potential to be used as a substitute for Bis-GMA. PMID:26282076

  8. High-Efficiency dc/dc Converter

    NASA Technical Reports Server (NTRS)

    Sturman, J.

    1982-01-01

    High-efficiency dc/dc converter has been developed that provides commonly used voltages of plus or minus 12 Volts from an unregulated dc source of from 14 to 40 Volts. Unique features of converter are its high efficiency at low power level and ability to provide output either larger or smaller than input voltage.

  9. Effects of resin formulation and nanofiller surface treatment on the properties of experimental hybrid resin composite.

    PubMed

    Musanje, Lawrence; Ferracane, Jack L

    2004-08-01

    This study evaluated the effects of nanofiller surface treatment and resin viscosity on the early and long-term properties of experimental hybrid composites. Three resin formulations (low, medium and high viscosity) were prepared by varying the ratio of TEGDMA:UDMA:bis-GMA (47:33:16 wt%; 30:33:33 wt%; 12:33:51 wt%). Composites contained 71.3 wt% silanated strontium glass (1-3 microm) and 12.6 wt% of either silanated or unsilanated silica (OX-50; 0.04 microm). Specimens (n=10) for flexural strength, flexural modulus, fracture toughness and Knoop hardness were tested after 24 h, 1 and 6 months exposure to water at 37 degrees C. Degree of conversion (DC) was determined 24 h after photoinitiation using FTIR. Resin viscosity only had a marginal influence on the mechanical response of composites but it can be adjusted to achieve a balance between DC and mechanical properties. Adding non-bonded nanofiller to hybrid composites had no systematic effect on DC. Non-bonded nanofillers had no significant effect on the long-term properties of hybrid composites. PMID:15046897

  10. Ramp technique for dc partial discharge testing

    NASA Technical Reports Server (NTRS)

    Bever, R. S.

    1985-01-01

    The partial discharge (PD) data presently obtained by means of a stepwise ramp technique, for the cases of high voltage (HV) components and such resin-packaged HV devices as the Space Telescope's Faint Object Camera, is acquired separately on part-way ramps to rated voltage and on the intermediate voltage plateaus. For test specimens intended for dc service, this ramp method yields more data on insulation integrity than quiescent dc measurements, especially in the case of specimens of high resistivity which causes the discharge frequency to be deceptively low at constant dc voltage. During upward ramping the voltage distribution is capacitive, and the PD behavior resembles that of an ac test. Many more pulses are obtained in the voids without the heat otherwise generated by the application of 60-Hz ac. PD histograms are presented for various materials, with and without intentional defects.

  11. Incombustible resin composition

    NASA Technical Reports Server (NTRS)

    Akima, T.

    1982-01-01

    Incombustible resin compositions composed of aromatic compounds were obtained through (1) combustion polymer material and (2) bisphenol A or halogenated bisphenol A and bisphenol A diglycidl ether or halogenated bisphenol A diglycidyl ether. The aromatic compound is an adduct of bifunctional phenols and bifunctional epoxy resins.

  12. Delayed cure bismaleimide resins

    DOEpatents

    Not Available

    1982-08-12

    Prior art polybismaleimides begin to polymerize at or just above the melting point of the monomer. This patent describes new bismaleimide resins which have an increased pot life and provide longer time periods in which the monomer remains fluid. The resins can be polymerized into molded articles with a high uniformity of properties. (DLC)

  13. DC/DC Converter Stability Testing Study

    NASA Technical Reports Server (NTRS)

    Wang, Bright L.

    2008-01-01

    This report presents study results on hybrid DC/DC converter stability testing methods. An input impedance measurement method and a gain/phase margin measurement method were evaluated to be effective to determine front-end oscillation and feedback loop oscillation. In particular, certain channel power levels of converter input noises have been found to have high degree correlation with the gain/phase margins. It becomes a potential new method to evaluate stability levels of all type of DC/DC converters by utilizing the spectral analysis on converter input noises.

  14. Development of resins for composites by resin transfer molding

    NASA Technical Reports Server (NTRS)

    Woo, Edmund P.; Puckett, Paul M.; Maynard, Shawn J.

    1991-01-01

    Designed to cover a wide range of resin technology and to meet the near-term and long-term needs of the aircraft industry, this research has three objectives: to produce resin transfer molding (RES) resins with improved processability, to produce prepreg systems with high toughness and service temperature, and to produce new resin systems. Progress on reaching the objectives is reported.

  15. Effect of Different Thicknesses of Pressable Ceramic Veneers on Polymerization of Light-cured and Dual-cured Resin Cements

    PubMed Central

    Cho, Seok-Hwan; Lopez, Arnaldo; Berzins, David W.; Prasad, Soni; Ahn, Kwang Woo

    2015-01-01

    Aim This study evaluated the effects of ceramic veneer thicknesses on the polymerization of two different resin cements. Materials and Methods A total of 80 ceramic veneer discs were fabricated by using a pressable ceramic material (e.max Press; Ivoclar Vivadent) from a Low Translucency (LT) ingot (A1 shade). These discs were divided into light-cured (LC; NX3 Nexus LC; Kerr) and dual-cured (DC; NX3 Nexus DC; Kerr) and each group was further divided into 4 subgroups, based on ceramic disc thickness (0.3 mm, 0.6 mm, 0.9 mm, and 1.2 mm). The values of Vickers microhardness (MH) and degree of conversion (DOC) were obtained for each specimen after a 24-hour storage period. Association between ceramic thickness, resin cement type, and light intensity readings (mW/cm2) with respect to microhardness and degree of conversion was statistically evaluated by using ANOVA. Results For the DOC values, there was no significant difference observed among the LC resin cement subgroups, except in the 1.2 mm subgroup; only the DOC value (14.0 ± 7.4%) of 1.2 mm DC resin cement had significantly difference from that value (28.9 ± 7.5%) of 1.2 mm LC resin cement (P<.05). For the MH values between LC and DC resin cement groups, there was statistically significant difference (P<.05); overall, the MH values of LC resin cement groups demonstrated higher values than DC resin cement groups. On the other hands, among the DC resin cement subgroups, the MH values of 1.2 mm DC subgroup was significantly lower than the 0.3 mm and 0.6 mm subgroups (P<.05). However, among the LC subgroups, there was no statistically significant difference among them (P >.05). Conclusion The degree of conversion and hardness of the resin cement was unaffected with veneering thicknesses between 0.3 and 0.9 mm. However, the DC resin cement group resulted in a significantly lower DOC and MH values for the 1.2 mm subgroup. Clinical Significance While clinically adequate polymerization of LC resin cement can be achieved

  16. Biocompatibility of composite resins

    PubMed Central

    Mousavinasab, Sayed Mostafa

    2011-01-01

    Dental materials that are used in dentistry should be harmless to oral tissues, so they should not contain any leachable toxic and diffusible substances that can cause some side effects. Reports about probable biologic hazards, in relation to dental resins, have increased interest to this topic in dentists. The present paper reviews the articles published about biocompatibility of resin-restorative materials specially resin composites and monomers which are mainly based on Bis-GMA and concerns about their degradation and substances which may be segregated into oral cavity. PMID:23372592

  17. Biocidal quaternary ammonium resin

    NASA Technical Reports Server (NTRS)

    Janauer, G. E.

    1983-01-01

    Activated carbon (charcoal) and polymeric resin sorbents are widely used in the filtration and treatment of drinking water, mainly to remove dissolved organic and inorganic impurities and to improve the taste. Earlier hopes that activated carbon might "disinfect' water proved to be unfounded. The feasibility of protecting against microbial infestation in charcoal and resin beds such as those to be incorporated into total water reuse systems in spacecraft was investigated. The biocidal effect of IPCD (insoluable polymeric contact disinfectants) in combination with a representative charcoal was assessed. The ion exchange resins (IPCD) were shown to adequately protect charcoal and ion exchange beds.

  18. Thermally stable laminating resins

    NASA Technical Reports Server (NTRS)

    Jones, R. J.; Vaughan, R. W.; Burns, E. A.

    1972-01-01

    Improved thermally stable laminating resins were developed based on the addition-type pyrolytic polymerization. Detailed monomer and polymer synthesis and characterization studies identified formulations which facilitate press molding processing and autoclave fabrication of glass and graphite fiber reinforced composites. A specific resin formulation, termed P10P was utilized to prepare a Courtaulds HMS reinforced simulated airfoil demonstration part by an autoclave molding process.

  19. Acetylene terminated matrix resins

    NASA Technical Reports Server (NTRS)

    Goldfarb, I. J.; Lee, Y. C.; Arnold, F. E.; Helminiak, T. E.

    1985-01-01

    The synthesis of resins with terminal acetylene groups has provided a promising technology to yield high performance structural materials. Because these resins cure through an addition reaction, no volatile by-products are produced during the processing. The cured products have high thermal stability and good properties retention after exposure to humidity. Resins with a wide variety of different chemical structures between the terminal acetylene groups are synthesized and their mechanical properties studied. The ability of the acetylene cured polymers to give good mechanical properties is demonstrated by the resins with quinoxaline structures. Processibility of these resins can be manipulated by varying the chain length between the acetylene groups or by blending in different amounts of reactive deluents. Processing conditions similar to the state-of-the-art epoxy can be attained by using backbone structures like ether-sulfone or bis-phenol-A. The wide range of mechanical properties and processing conditions attainable by this class of resins should allow them to be used in a wide variety of applications.

  20. Repair bond strength of dual-cured resin composite core buildup materials

    PubMed Central

    El-Deeb, Heba A.; Ghalab, Radwa M.; Elsayed Akah, Mai M.; Mobarak, Enas H.

    2015-01-01

    The reparability of dual-cured resin composite core buildup materials using a light-cured one following one week or three months storage, prior to repair was evaluated. Two different dual-cured resin composites; Cosmecore™ DC automix and Clearfil™ DC automix core buildup materials and a light-cured nanofilled resin composite; Filtek™ Z350 XT were used. Substrate specimens were prepared (n = 12/each substrate material) and stored in artificial saliva at 37 °C either for one week or three months. Afterward, all specimens were ground flat, etched using Scotchbond™ phosphoric acid etchant and received Single Bond Universal adhesive system according to the manufacturers’ instructions. The light-cured nanofilled resin composite (Filtek™ Z350 XT) was used as a repair material buildup. To determine the cohesive strength of each solid substrate material, additional specimens from each core material (n = 12) were prepared and stored for the same periods. Five sticks (0.8 ± 0.01 mm2) were obtained from each specimen (30 sticks/group) for microtensile bond strength (μTBS) testing. Modes of failure were also determined. Two-way ANOVA revealed a significant effect for the core materials but not for the storage periods or their interaction. After one week, dual-cured resin composite core buildup materials (Cosmecore™ DC and Clearfil™ DC) achieved significantly higher repair μTBS than the light-cured nanofilled resin composite (Filtek™ Z350 XT). However, Clearfil™ DC revealed the highest value, then Cosmecore™ DC and Filtek™ Z350 XT, following storage for 3-month. Repair strength values recovered 64–86% of the cohesive strengths of solid substrate materials. The predominant mode of failure was the mixed type. Dual-cured resin composite core buildup materials revealed acceptable repair bond strength values even after 3-month storage. PMID:26966567

  1. DC source assemblies

    DOEpatents

    Campbell, Jeremy B; Newson, Steve

    2013-02-26

    Embodiments of DC source assemblies of power inverter systems of the type suitable for deployment in a vehicle having an electrically grounded chassis are provided. An embodiment of a DC source assembly comprises a housing, a DC source disposed within the housing, a first terminal, and a second terminal. The DC source also comprises a first capacitor having a first electrode electrically coupled to the housing, and a second electrode electrically coupled to the first terminal. The DC source assembly further comprises a second capacitor having a first electrode electrically coupled to the housing, and a second electrode electrically coupled to the second terminal.

  2. Graphite fiber reinforced thermoplastic resins

    NASA Technical Reports Server (NTRS)

    Novak, R. C.

    1975-01-01

    Mechanical properties of neat resin samples and graphite fiber reinforced samples of thermoplastic resins were characterized with particular emphasis directed to the effects of environmental exposure (humidity, temperature and ultraviolet radiation). Tensile, flexural, interlaminar shear, creep and impact strengths were measured for polysulfone, polyarylsulfone and a state-of-the-art epoxy resin samples. In general, the thermoplastic resins exhibited environmental degradation resistance equal to or superior to the reference epoxy resin. Demonstration of the utility and quality of a graphite/thermoplastic resin system was accomplished by successfully thermoforming a simulated compressor blade and a fan exit guide vane.

  3. Method for removing contaminants from plastic resin

    DOEpatents

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2008-12-09

    A resin recycling method that produces essentially contaminant-free synthetic resin material in an environmentally safe and economical manner. The method includes receiving the resin in container form. The containers are then ground into resin particles. The particles are exposed to a solvent, the solvent contacting the resin particles and substantially removing contaminants on the resin particles. After separating the particles and the resin, a solvent removing agent is used to remove any residual solvent remaining on the resin particles after separation.

  4. Radiation effects on DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Zhang, Dexin; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2000-01-01

    DC-DC switching converters are circuits that can be used to convert a DC voltage of one value to another by switching action. They are increasing being used in space systems. Most of the popular DC-DC switching converters utilize power MOSFETs. However power MOSFETs, when subjected to radiation, are susceptible to degradation of device characteristics or catastrophic failure. This work focuses on the effects of total ionizing dose on converter performance. Four fundamental switching converters (buck converter, buck-boost converter, cuk converter, and flyback converter) were built using Harris IRF250 power MOSFETs. These converters were designed for converting an input of 60 volts to an output of about 12 volts with a switching frequency of 100 kHz. The four converters were irradiated with a Co-60 gamma source at dose rate of 217 rad/min. The performances of the four converters were examined during the exposure to the radiation. The experimental results show that the output voltage of the converters increases as total dose increases. However, the increases of the output voltage were different for the four different converters, with the buck converter and cuk converter the highest and the flyback converter the lowest. We observed significant increases in output voltage for cuk converter at a total dose of 24 krad (si).

  5. Phosphonic acid based exchange resins

    DOEpatents

    Horwitz, E.P.; Alexandratos, S.D.; Gatrone, R.C.; Chiarizia, R.

    1995-09-12

    An ion exchange resin is described for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene. 10 figs.

  6. Phosphonic acid based exchange resins

    DOEpatents

    Horwitz, E. Philip; Alexandratos, Spiro D.; Gatrone, Ralph C.; Chiarizia, Ronato

    1995-01-01

    An ion exchange resin for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene.

  7. Epoxy resin holograms

    NASA Astrophysics Data System (ADS)

    Ruiz-Limón, B.; Wetzel, G. B. J.; Olivares Pérez, A.; Ponce-Lee, E. L.; Ramos-Garcia, R.; Toxqui López, S.; Hernández-Garay, M. P.; Fuentes-Tapia, I.

    2006-02-01

    We observed that a commercial epoxy resin (Comex (R) is enable to record images by means of lithography techniques. We can generate a hologram using a digital image and a computer simulation program and transferred it on our resin by microlithography techniques to get a phase hologram and increase its efficiency. The exposition to the heat produce temperature gradients and the information in the mask is transferred to the material by the refraction index changes, thus the film is recorded. At the same time the hologram is cured.

  8. DC-to-DC switching converter

    NASA Technical Reports Server (NTRS)

    Cuk, Slobodan M. (Inventor); Middlebrook, Robert D. (Inventor)

    1980-01-01

    A dc-to-dc converter having nonpulsating input and output current uses two inductances, one in series with the input source, the other in series with the output load. An electrical energy transferring device with storage, namely storage capacitance, is used with suitable switching means between the inductances to DC level conversion. For isolation between the source and load, the capacitance may be divided into two capacitors coupled by a transformer, and for reducing ripple, the inductances may be coupled. With proper design of the coupling between the inductances, the current ripple can be reduced to zero at either the input or the output, or the reduction achievable in that way may be divided between the input and output.

  9. Radiation Effects on DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Zhang, De-Xin; AbdulMazid, M. D.; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2001-01-01

    In this work, several DC-DC converters were designed and built. The converters are Buck Buck-Boost, Cuk, Flyback, and full-bridge zero-voltage switched. The total ionizing dose radiation and single event effects on the converters were investigated. The experimental results for the TID effects tests show that the voltages of the Buck Buck-Boost, Cuk, and Flyback converters increase as total dose increased when using power MOSFET IRF250 as a switching transistor. The change in output voltage with total dose is highest for the Buck converter and the lowest for Flyback converter. The trend of increase in output voltages with total dose in the present work agrees with those of the literature. The trends of the experimental results also agree with those obtained from PSPICE simulation. For the full-bridge zero-voltage switch converter, it was observed that the dc-dc converter with IRF250 power MOSFET did not show a significant change of output voltage with total dose. In addition, for the dc-dc converter with FSF254R4 radiation-hardened power MOSFET, the output voltage did not change significantly with total dose. The experimental results were confirmed by PSPICE simulation that showed that FB-ZVS converter with IRF250 power MOSFET's was not affected with the increase in total ionizing dose. Single Event Effects (SEE) radiation tests were performed on FB-ZVS converters. It was observed that the FB-ZVS converter with the IRF250 power MOSFET, when the device was irradiated with Krypton ion with ion-energy of 150 MeV and LET of 41.3 MeV-square cm/mg, the output voltage increased with the increase in fluence. However, for Krypton with ion-energy of 600 MeV and LET of 33.65 MeV-square cm/mg, and two out of four transistors of the converter were permanently damaged. The dc-dc converter with FSF254R4 radiation hardened power MOSFET's did not show significant change at the output voltage with fluence while being irradiated by Krypton with ion energy of 1.20 GeV and LET of 25

  10. Resin impregnation process for producing a resin-fiber composite

    NASA Technical Reports Server (NTRS)

    Palmer, Raymond J. (Inventor); Moore, William E. (Inventor)

    1994-01-01

    Process for vacuum impregnation of a dry fiber reinforcement with a curable resin to produce a resin-fiber composite, by drawing a vacuum to permit flow of curable liquid resin into and through a fiber reinforcement to impregnate same and curing the resin-impregnated fiber reinforcement at a sufficient temperature and pressure to effect final curing. Both vacuum and positive pressure, e.g. autoclave pressure, are applied to the dry fiber reinforcement prior to application of heat and prior to any resin flow to compact the dry fiber reinforcement, and produce a resin-fiber composite of reduced weight, thickness and resin content, and improved mechanical properties. Preferably both a vacuum and positive pressure, e.g. autoclave pressure, are also applied during final curing.

  11. Influence of irradiance on Knoop hardness, degree of conversion, and polymerization shrinkage of nanofilled and microhybrid composite resins.

    PubMed

    Fugolin, Ana Paula Piovezan; Correr-Sobrinho, Lourenço; Correr, Américo Bortolazzo; Sinhoreti, Mário Alexandre Coelho; Guiraldo, Ricardo Danil; Consani, Simonides

    2016-01-01

    The purpose of this study was to investigate the influence of the irradiance emitted by a light-curing unit on microhardness, degree of conversion (DC), and gaps resulting from shrinkage of 2 dental composite resins. Cylinders of nanofilled and microhybrid composites were fabricated and light cured. After 24 hours, the tops and bottoms of the specimens were evaluated via indentation testing and Fourier transform infrared spectroscopy to determine Knoop hardness number (KHN) and DC, respectively. Gap width (representing polymerization shrinkage) was measured under a scanning electron microscope. The nanofilled composite specimens presented significantly greater KHNs than did the microhybrid specimens (P < 0.05). The microhybrid composite resin exhibited significantly greater DC and gap width than the nanofilled material (P < 0.05). Irradiance had a mostly material-dependent influence on the hardness and DC, but not the polymerization shrinkage, of composite resins. PMID:26943085

  12. Nontoxic Resins Advance Aerospace Manufacturing

    NASA Technical Reports Server (NTRS)

    2009-01-01

    The 2008 NASA Commercial Invention of the Year, PETI-330, is a polyimide matrix resin that performs well at high temperatures and is easily processed into composites in a simple, short curing cycle. Invented by scientists at Langley Research Center, PETI-330 is now licensed to Ube Industries, based in Japan with its American headquarters in New York. In addition to being durable and lightweight, the resin is also nontoxic, which makes it safe for workers to handle. PETI-330 was created specifically for heat-resistant composites formed with resin transfer molding and resin infusion, which formerly could only be used with low temperature resin systems.

  13. Adsorption of three pharmaceuticals on two magnetic ion-exchange resins.

    PubMed

    Jiang, Miao; Yang, Weiben; Zhang, Ziwei; Yang, Zhen; Wang, Yuping

    2015-05-01

    The presence of pharmaceuticals in aquatic environments poses potential risks to the ecology and human health. This study investigated the removal of three widely detected and abundant pharmaceuticals, namely, ibuprofen (IBU), diclofenac (DC), and sulfadiazine (SDZ), by two magnetic ion-exchange resins. The adsorption kinetics of the three adsorbates onto both resins was relatively fast and followed pseudo-second-order kinetics. Despite the different pore structures of the two resins, similar adsorption patterns of DC and SDZ were observed, implying the existence of an ion-exchange mechanism. IBU demonstrated a combination of interactions during the adsorption process. These interactions were dependent on the specific surface area and functional groups of the resin. The adsorption isotherm fittings verified the differences in the behavior of the three pharmaceuticals on the two magnetic ion-exchange resins. The presence of Cl- and SO4(2-) suppressed the adsorption amount, but with different inhibition levels for different adsorbates. This work facilitates the understanding of the adsorption behavior and mechanism of pharmaceuticals on magnetic ion-exchange resins. The results will expand the application of magnetic ion-exchange resins to the removal of pharmaceuticals in waters. PMID:25968278

  14. Preparation and Evaluation of Dental Resin with Antibacterial and Radio-Opaque Functions

    PubMed Central

    He, Jingwei; Söderling, Eva; Vallittu, Pekka K.; Lassila, Lippo V. J.

    2013-01-01

    In order to prepare antibacterial and radio-opaque dental resin, a methacrylate monomer named 2-Dimethyl-2-dodecyl-1-methacryloxyethyl ammonium iodine (DDMAI) with both antibacterial and radio-opaque activities was added into a 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropyl)-phenyl]propane (Bis-GMA)/methyl methacrylate (MMA) dental resin system. Degree of conversion (DC), flexural strength (FS) and modulus (FM), water sorption (WS) and solubility (WSL), antibacterial activity, and radio-opacity (ROX) of the obtained dental resin system were investigated. Bis-GMA/MMA resin system without DDMAI was used as a control. The results showed that DDMAI could endow BIS-GMA/MMA resin system with good antibacterial (p < 0.05) and radio-opaque function without influencing the DC (p > 0.05). However, incorporating DDMAI into Bis-GMA/MMA resin could reduce mechanical properties (p < 0.05) and increase WS and WSL (p < 0.05), thus further work is needed in order to optimize the resin formulation. PMID:23470923

  15. Multilevel DC link inverter

    DOEpatents

    Su, Gui-Jia

    2003-06-10

    A multilevel DC link inverter and method for improving torque response and current regulation in permanent magnet motors and switched reluctance motors having a low inductance includes a plurality of voltage controlled cells connected in series for applying a resulting dc voltage comprised of one or more incremental dc voltages. The cells are provided with switches for increasing the resulting applied dc voltage as speed and back EMF increase, while limiting the voltage that is applied to the commutation switches to perform PWM or dc voltage stepping functions, so as to limit current ripple in the stator windings below an acceptable level, typically 5%. Several embodiments are disclosed including inverters using IGBT's, inverters using thyristors. All of the inverters are operable in both motoring and regenerating modes.

  16. Radiation-Tolerant DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Skutt, Glenn; Sable, Dan; Leslie, Leonard; Graham, Shawn

    2012-01-01

    A document discusses power converters suitable for space use that meet the DSCC MIL-PRF-38534 Appendix G radiation hardness level P classification. A method for qualifying commercially produced electronic parts for DC-DC converters per the Defense Supply Center Columbus (DSCC) radiation hardened assurance requirements was developed. Development and compliance testing of standard hybrid converters suitable for space use were completed for missions with total dose radiation requirements of up to 30 kRad. This innovation provides the same overall performance as standard hybrid converters, but includes assurance of radiation- tolerant design through components and design compliance testing. This availability of design-certified radiation-tolerant converters can significantly reduce total cost and delivery time for power converters for space applications that fit the appropriate DSCC classification (30 kRad).

  17. High-temperature resins

    NASA Technical Reports Server (NTRS)

    Serafini, T. T.

    1982-01-01

    The basic chemistry, cure processes, properties, and applications of high temperature resins known as polyimides are surveyed. Condensation aromatic polymides are prepared by reacting aromatic diamines with aromatic dianhydrides, aromatic tetracarboxylic acids, or with dialkyl esters of aromatic tetracarboxylic acids, depending on the intended end use. The first is for coatings or films while the latter two are more suitable for polyimide matrix resins. Prepreg solutions are made by dissolving reactants in an aprotic solvent, and advances in the addition of a diamine on the double bond and radical polymerization of the double bond are noted to have yielded a final cure product with void-free characteristics. Attention is given to properties of the Skybond, Pyralin, and NR-150B polyimide prepreg materials and characteristics of aging in the NP-150 polyimides. Finally, features of the NASA-developed PMR polyimides are reviewed.

  18. Flame Retardant Epoxy Resins

    NASA Technical Reports Server (NTRS)

    Thompson, C. M.; Smith, J. G., Jr.; Connell, J. W.; Hergenrother, P. M.; Lyon, R. E.

    2004-01-01

    As part of a program to develop fire resistant exterior composite structures for future subsonic commercial aircraft, flame retardant epoxy resins are under investigation. Epoxies and their curing agents (aromatic diamines) containing phosphorus were synthesized and used to prepare epoxy formulations. Phosphorus was incorporated within the backbone of the epoxy resin and not used as an additive. The resulting cured epoxies were characterized by thermogravimetric analysis, propane torch test, elemental analysis and microscale combustion calorimetry. Several formulations showed excellent flame retardation with phosphorous contents as low as 1.5% by weight. The fracture toughness of plaques of several cured formulations was determined on single-edge notched bend specimens. The chemistry and properties of these new epoxy formulations are discussed.

  19. Bismaleimide Copolymer Matrix Resins

    NASA Technical Reports Server (NTRS)

    Parker, John A.; Heimbuch, Alvin H.; Hsu, Ming-Ta S.; Chen, Timothy S.

    1987-01-01

    Graphite composites, prepared from 1:1 copolymer of two new bismaleimides based on N,N'-m-phenylene-bis(m-amino-benzamide) structure have mechanical properties superior to those prepared from other bismaleimide-type resins. New heat-resistant composites replace metal in some structural applications. Monomers used to form copolymers with superior mechanical properties prepared by reaction of MMAB with maleic or citraconic anhydride.

  20. Forback DC-to-DC converter

    NASA Technical Reports Server (NTRS)

    Lukemire, Alan T. (Inventor)

    1995-01-01

    A pulse-width modulated DC-to-DC power converter including a first inductor, i.e. a transformer or an equivalent fixed inductor equal to the inductance of the secondary winding of the transformer, coupled across a source of DC input voltage via a transistor switch which is rendered alternately conductive (ON) and nonconductive (OFF) in accordance with a signal from a feedback control circuit is described. A first capacitor capacitively couples one side of the first inductor to a second inductor which is connected to a second capacitor which is coupled to the other side of the first inductor. A circuit load shunts the second capacitor. A semiconductor diode is additionally coupled from a common circuit connection between the first capacitor and the second inductor to the other side of the first inductor. A current sense transformer generating a current feedback signal for the switch control circuit is directly coupled in series with the other side of the first inductor so that the first capacitor, the second inductor and the current sense transformer are connected in series through the first inductor. The inductance values of the first and second inductors, moreover, are made identical. Such a converter topology results in a simultaneous voltsecond balance in the first inductance and ampere-second balance in the current sense transformer.

  1. Forback DC-to-DC converter

    NASA Technical Reports Server (NTRS)

    Lukemire, Alan T. (Inventor)

    1993-01-01

    A pulse-width modulated DC-to-DC power converter including a first inductor, i.e. a transformer or an equivalent fixed inductor equal to the inductance of the secondary winding of the transformer, coupled across a source of DC input voltage via a transistor switch which is rendered alternately conductive (ON) and nonconductive (OFF) in accordance with a signal from a feedback control circuit is described. A first capacitor capacitively couples one side of the first inductor to a second inductor which is connected to a second capacitor which is coupled to the other side of the first inductor. A circuit load shunts the second capacitor. A semiconductor diode is additionally coupled from a common circuit connection between the first capacitor and the second inductor to the other side of the first inductor. A current sense transformer generating a current feedback signal for the switch control circuit is directly coupled in series with the other side of the first inductor so that the first capacitor, the second inductor and the current sense transformer are connected in series through the first inductor. The inductance values of the first and second inductors, moreover, are made identical. Such a converter topology results in a simultaneous voltsecond balance in the first inductance and ampere-second balance in the current sense transformer.

  2. System for removing contaminants from plastic resin

    DOEpatents

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2010-11-23

    A resin recycling system that produces essentially contaminant-free synthetic resin material in an environmentally safe and economical manner. The system includes receiving the resin in container form. A grinder grinds the containers into resin particles. The particles are exposed to a solvent in one or more solvent wash vessels, the solvent contacting the resin particles and substantially removing contaminants on the resin particles. A separator is used to separate the resin particles and the solvent. The resin particles are then placed in solvent removing element where they are exposed to a solvent removing agent which removes any residual solvent remaining on the resin particles after separation.

  3. Advanced thermoplastic resins, phase 1

    NASA Technical Reports Server (NTRS)

    Hendricks, C. L.; Hill, S. G.; Falcone, A.; Gerken, N. T.

    1991-01-01

    Eight thermoplastic polyimide resin systems were evaluated as composite matrix materials. Two resins were selected for more extensive mechanical testing and both were versions of LaRC-TPI (Langley Research Center - Thermoplastic Polyimide). One resin was made with LaRC-TPI and contained 2 weight percent of a di(amic acid) dopant as a melt flow aid. The second system was a 1:1 slurry of semicrystalline LaRC-TPI powder in a polyimidesulfone resin diglyme solution. The LaRC-TPI powder melts during processing and increases the melt flow of the resin. Testing included dynamic mechanical analysis, tension and compression testing, and compression-after-impact testing. The test results demonstrated that the LaRC-TPI resins have very good properties compared to other thermoplastics, and that they are promising matrix materials for advanced composite structures.

  4. Vitrification of ion exchange resins

    DOEpatents

    Cicero-Herman, Connie A.; Workman, Rhonda Jackson

    2001-01-01

    The present invention relates to vitrification of ion exchange resins that have become loaded with hazardous or radioactive wastes, in a way that produces a homogenous and durable waste form and reduces the disposal volume of the resin. The methods of the present invention involve directly adding borosilicate glass formers and an oxidizer to the ion exchange resin and heating the mixture at sufficient temperature to produce homogeneous glass.

  5. Correlation between clinical performance and degree of conversion of resin cements: a literature review

    PubMed Central

    DE SOUZA, Grace; BRAGA, Roberto Ruggiero; CESAR, Paulo Francisco; LOPES, Guilherme Carpena

    2015-01-01

    Resin-based cements have been frequently employed in clinical practice to lute indirect restorations. However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photo-cured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC) under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. Specific measures are to be taken to ensure a higher DC of the luting system to be used. PMID:26398507

  6. Intelligent dc-dc Converter Technology Developed and Tested

    NASA Technical Reports Server (NTRS)

    Button, Robert M.

    2001-01-01

    The NASA Glenn Research Center and the Cleveland State University have developed a digitally controlled dc-dc converter to research the benefits of flexible, digital control on power electronics and systems. Initial research and testing has shown that conventional dc-dc converters can benefit from improved performance by using digital-signal processors and nonlinear control algorithms.

  7. Phosphorus-containing bisimide resins

    NASA Technical Reports Server (NTRS)

    Varma, I. K.; Fohlen, G. M.; Parker, J. A. (Inventor)

    1981-01-01

    The production of fire-resistant resins particularly useful for making laminates with inorganic fibers such as graphite fibers is discussed. The resins are by (1) condensation of an ethylenically unsaturated cyclic anhydride with a bis(diaminophenyl) phosphine oxide, and (2) by addition polymerization of the bisimide so obtained. Up to about 50%, on a molar basis, of benzophenonetetracarboxylic acid anhydride can be substituted for some of the cyclic anhydride to alter the properties of the products. Graphite cloth laminates made with these resins show 800 C char yields greater than 70% by weight in nitrogen. Limiting oxygen indexes of more than 100% are determined for these resins.

  8. A new polyimide laminatine resin

    NASA Technical Reports Server (NTRS)

    Barrick, J. D. W.; Jewell, R. A.; Stclair, T. L.

    1977-01-01

    Addition polyimide for composite materials is based on liquid monomers and has significant advantages over most existing high-temperature resins. Essentially solventless prepreg has improved drape, tack.

  9. PRESENCE OF DICHLOROMETHANE ON CLEANED XAD-2 RESIN: A POTENTIAL PROBLEM AND SOLUTIONS

    EPA Science Inventory

    Preparation of XAD-2 resin for indoor air sampling with commonly used cleaning methods, such as Soxhlet extraction with dichloromethane (DCM) followed by vacuum drying and nitrogen purging, can lead to elevated DCM levels (>100 ppb) in the sampled indoor air, which result from DC...

  10. Synthesis of a liquid-crystalline resin monomer with the property of low shrinkage polymerization.

    PubMed

    Liu, Wenwen; Chen, Su; Liu, Yiran; Ma, Yuanping; Wang, Na; Zhang, Zhenting; Yang, Yuzhe

    2013-01-01

    To reduce the polymerization shrinkage of the dental resin composites, a new liquid-crystalline resin monomer was developed. The acrylate liquid crystalline resin monomer (ALCRM), (4-3-(acryloyloxy)-2-hydroxypropoxy) phenyl 4-(3-(acryloyloxy)-2-hydroxypropoxy) benzoate, was synthesized by a three-step method. Using the ALCRM as the main monomer, the degree of conversion (DC) and the volume shrinkage of the resin matrix were compared with the traditional composite resin monomer (Bis-GMA), 2,2-bis[4-(2-hydroxy-3-methacryloyloxy-propoxy)-phenyl] propane. The new monomer showed liquid crystalline characteristics with a mesomorphic phasetransition temperature between 18ºC and 42ºC. When copolymerized with triethylene glycol dimethacrylate (TEGDMA) at a weight ratio of 7:3, the DC of ALCRM was higher and the volume shrinkage was 3.62±0.26%, which was less than that of the Bis-GMA. The ALCRM exhibits promising potential for the development of superior dental resins with low volume shrinkage. PMID:23903635

  11. 40 CFR 414.50 - Applicability; description of the thermosetting resins subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... the products classified under SIC 28214 thermosetting resins including those resins and resin groups listed below. Product groups are indicated with an asterisk (*). *Alkyd Resins Dicyanodiamide Resin *Epoxy Resins *Fumaric Acid Polyesters *Furan Resins Glyoxal-Urea Formaldehyde Textile Resin...

  12. 40 CFR 414.50 - Applicability; description of the thermosetting resins subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... the products classified under SIC 28214 thermosetting resins including those resins and resin groups listed below. Product groups are indicated with an asterisk (*). *Alkyd Resins Dicyanodiamide Resin *Epoxy Resins *Fumaric Acid Polyesters *Furan Resins Glyoxal-Urea Formaldehyde Textile Resin...

  13. 40 CFR 414.50 - Applicability; description of the thermosetting resins subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... the products classified under SIC 28214 thermosetting resins including those resins and resin groups listed below. Product groups are indicated with an asterisk (*). *Alkyd Resins Dicyanodiamide Resin *Epoxy Resins *Fumaric Acid Polyesters *Furan Resins Glyoxal-Urea Formaldehyde Textile Resin...

  14. 40 CFR 414.50 - Applicability; description of the thermosetting resins subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... the products classified under SIC 28214 thermosetting resins including those resins and resin groups listed below. Product groups are indicated with an asterisk (*). *Alkyd Resins Dicyanodiamide Resin *Epoxy Resins *Fumaric Acid Polyesters *Furan Resins Glyoxal-Urea Formaldehyde Textile Resin...

  15. 40 CFR 414.50 - Applicability; description of the thermosetting resins subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... the products classified under SIC 28214 thermosetting resins including those resins and resin groups listed below. Product groups are indicated with an asterisk (*). *Alkyd Resins Dicyanodiamide Resin *Epoxy Resins *Fumaric Acid Polyesters *Furan Resins Glyoxal-Urea Formaldehyde Textile Resin...

  16. Imide modified epoxy matrix resins

    NASA Technical Reports Server (NTRS)

    Scola, D. A.; Pater, R. H.

    1981-01-01

    High char yield epoxy using novel bisimide amines (BIA's) as curing agents with a state of the art epoxy resin was developed. Stoichiometric quantities of the epoxy resin and the BIA's were studied to determine the cure cycle required for preparation of resin specimens. The bisimide cured epoxies were designated IME's (imide modified epoxy). The physical, thermal and mechanical properties of these novel resins were determined. The levels of moisture absorption exhibited by the bisimide amine cured expoxies (IME's) were considerably lower than the state of the art epoxies. The strain-to-failure of the control resin system was improved 25% by replacement of DDS with 6F-DDS. Each BIA containing resin exhibited twice the char yield of the control resin MY 720/DDS. Graphite fiber reinforced control (C) and IME resins were fabricated and characterized. Two of the composite systems showed superior properties compared to the other Celion 6000/IME composite systems and state of the art graphite epoxy systems. The two systems exhibited excellent wet shear and flexural strengths and moduli at 300 and 350 F.

  17. Preparation and characterization of Bis-GMA free dental resin system with synthesized dimethacrylate monomer TDDMMA derived from tricyclo[5.2.1.0(2,6)]-decanedimethanol.

    PubMed

    Yin, Mei; Liu, Fang; He, Jingwei

    2016-04-01

    As a substitute for 2,2-bis[4-(2-hydroxy-3- methacryloxypropoxy)phenyl] propane (Bis-GMA) in dental materials, a new dimethacrylate monomer TDDMMA without bisphenol-A structure was synthesized through the reaction between tricyclo[5.2.1.0(2,6)]- decanedimethanol and 2-isocyanatoethyl methacrylate. The TDDMMA was mixed with triethylene glycol dimethacrylate (TEGDMA) to prepare Bis-GMA free dental resin. Physicochemical properties, such as double bond conversion (DC), polymerization shrinkage (VS), water sorption (WS) and solubility (SL), flexural strength (FS) and modulus (FM) and fracture energy of TDDMMA/TEGDMA resin system were investigated. Bis-GMA/TEGDMA resin system was used as a control. The results showed that, compared with Bis-GMA/TEGDMA resin system, TDDMMA/TEGDMA resin system had comparable VS and several advantages like higher DC, lower SL and better mechanical properties after water immersion. PMID:26717250

  18. RISK D/C

    NASA Technical Reports Server (NTRS)

    Dias, W. C.

    1994-01-01

    RISK D/C is a prototype program which attempts to do program risk modeling for the Space Exploration Initiative (SEI) architectures proposed in the Synthesis Group Report. Risk assessment is made with respect to risk events, their probabilities, and the severities of potential results. The program allows risk mitigation strategies to be proposed for an exploration program architecture and to be ranked with respect to their effectiveness. RISK D/C allows for the fact that risk assessment in early planning phases is subjective. Although specific to the SEI in its present form, RISK D/C can be used as a framework for developing a risk assessment program for other specific uses. RISK D/C is organized into files, or stacks, of information, including the architecture, the hazard, and the risk event stacks. Although predefined, all stacks can be upgraded by a user. The architecture stack contains information concerning the general program alternatives, which are subsequently broken down into waypoints, missions, and mission phases. The hazard stack includes any background condition which could result in a risk event. A risk event is anything unfavorable that could happen during the course of a specific point within an architecture, and the risk event stack provides the probabilities, consequences, severities, and any mitigation strategies which could be used to reduce the risk of the event, and how much the risk is reduced. RISK D/C was developed for Macintosh series computers. It requires HyperCard 2.0 or later, as well as 2Mb of RAM and System 6.0.8 or later. A Macintosh II series computer is recommended due to speed concerns. The standard distribution medium for this package is one 3.5 inch 800K Macintosh format diskette. RISK D/C was developed in 1991 and is a copyrighted work with all copyright vested in NASA. Macintosh and HyperCard are trademarks of Apple Computer, Inc.

  19. Bond strength between acrylic resin and maxillofacial silicone

    PubMed Central

    HADDAD, Marcela Filié; GOIATO, Marcelo Coelho; dos SANTOS, Daniela Micheline; CREPALDI, Nádia de Marchi; PESQUEIRA, Aldiéris Alves; BANNWART, Lisiane Cristina

    2012-01-01

    The development of implant dentistry improved the possibilities of rehabilitation with maxillofacial prosthesis. However, clinically it is difficult to bond the silicone to the attachment system. Objectives This study aimed to evaluate the effect of an adhesive system on the bond strength between acrylic resin and facial silicone. Material and Methods A total of 120 samples were fabricated with auto-polymerized acrylic resin and MDX 4-4210 facial silicone. Both materials were bonded through mechanical retentions and/or application of primers (DC 1205 primer and Sofreliner primer S) and adhesive (Silastic Medical Adhesive Type A) or not (control group). Samples were divided into 12 groups according to the method used to attach the silicone to the acrylic resin. All samples were subjected to a T-peel test in a universal testing machine. Failures were classified as adhesive, cohesive or mixed. The data were evaluated by the analysis of variance (ANOVA) and the Tukey's HSD test (α=.05). Results The highest bond strength values (5.95 N/mm; 3.07 N/mm; 4.75 N/mm) were recorded for the samples that received a Sofreliner primer application. These values were significantly higher when the samples had no scratches and did not receive the application of Silastic Medical Adhesive Type A. Conclusions The most common type of failure was adhesive. The use of Sofreliner primer increased the bond strength between the auto-polymerized acrylic resin and the Silastic MDX 4-4210 facial silicone. PMID:23329247

  20. DC Breakdown Experiments

    SciTech Connect

    Calatroni, S.; Descoeudres, A.; Levinsen, Y.; Taborelli, M.; Wuensch, W.

    2009-01-22

    In the context of the CLIC (Compact Linear Collider) project investigations of DC breakdown in ultra high vacuum are carried out in parallel with high power RF tests. From the point of view of saturation breakdown field the best material tested so far is stainless steel, followed by titanium. Copper shows a four times weaker breakdown field than stainless steel. The results indicate clearly that the breakdown events are initiated by field emission current and that the breakdown field is limited by the cathode. In analogy to RF, the breakdown probability has been measured in DC and the data show similar behaviour as a function of electric field.

  1. DC attenuation meter

    DOEpatents

    Hargrove, Douglas L.

    2004-09-14

    A portable, hand-held meter used to measure direct current (DC) attenuation in low impedance electrical signal cables and signal attenuators. A DC voltage is applied to the signal input of the cable and feedback to the control circuit through the signal cable and attenuators. The control circuit adjusts the applied voltage to the cable until the feedback voltage equals the reference voltage. The "units" of applied voltage required at the cable input is the system attenuation value of the cable and attenuators, which makes this meter unique. The meter may be used to calibrate data signal cables, attenuators, and cable-attenuator assemblies.

  2. Degree of conversion of nanofilled and microhybrid composite resins photo-activated by different generations of LEDs

    PubMed Central

    RIBEIRO, Benicia Carolina Iaskieviscz; BOAVENTURA, Juliana Maria Capelozza; de BRITO-GONÇALVES, Joel; RASTELLI, Alessandra Nara de Souza; BAGNATO, Vanderlei Salvador; SAAD, José Roberto Cury

    2012-01-01

    Objective This study aimed at evaluating the degree of conversion (DC) of four composite resins, being one nanofilled and 3 microhybrid resins, photo-activated with second- and third-generation light-emitting diodes (LEDs). Material and methods FiltekTM Z350 nanofilled composite resins and Amelogen® Plus, Vit-l-escenceTM and Opallis microhybrid resins were photo-activated with two second-generation LEDs (Radii-cal and Elipar Free LightTM 2) and one third-generation LED (Ultra-Lume LED 5) by continuous light mode, and a quartz halogen-tungsten bulb (QHT, control). After 24 h of storage, the samples were pulverized into fine powder and 5 mg of each material were mixed with 100 mg of potassium bromide (KBr). After homogenization, they were pressed, which resulted in a pellet that was evaluated using an infrared spectromer (Nexus 470, Thermo Nicolet) equipped with TGS detector using diffuse reflectance (32 scans, resolution of 4 cm-1) coupled to a computer. The percentage of unreacted carbon-carbon double bonds (% C=C) was determined from the ratio of absorbance intensities of aliphatic C=C (peak at 1637 cm-1) against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm-1). Results The ANOVA showed a significant effect on the interaction between the light-curing units (LCUs) and the composite resins (p<0.001). The Tukey's test showed that the nanofilled resin (FiltekTM Z350) and Opallis when photo-activated by the halogen lamp (QTH) had the lowest DC compared with the other microhybrid composite resins. The DC of the nanofilled resin (FiltekTM Z350) was also lower using LEDs. The highest degrees of conversion were obtained using the third-generation LED and one of second-generation LEDs (Elipar Free LightTM 2). Conclusions The nanofilled resin showed the lowest DC, and the Vit-l-escenceTM microhybrid composite resin showed the highest DC. Among the LCUs, it was not possible to establish an order, even though the second

  3. Resin composite repair: Quantitative microleakage evaluation of resin-resin and resin-tooth interfaces with different surface treatments

    PubMed Central

    Celik, Cigdem; Cehreli, Sevi Burcak; Arhun, Neslihan

    2015-01-01

    Objective: The aim was to evaluate the effect of different adhesive systems and surface treatments on the integrity of resin-resin and resin-tooth interfaces after partial removal of preexisting resin composites using quantitative image analysis for microleakage testing protocol. Materials and Methods: A total of 80 human molar teeth were restored with either of the resin composites (Filtek Z250/GrandioSO) occlusally. The teeth were thermocycled (1000×). Mesial and distal 1/3 parts of the restorations were removed out leaving only middle part. One side of the cavity was finished with course diamond bur and the other was air-abraded with 50 μm Al2O3. They were randomly divided into four groups (n = 10) to receive: Group 1: Adper Single Bond 2; Group 2: All Bond 3; Group 3: ClearfilSE; Group 4: BeautiBond, before being repaired with the same resin composite (Filtek Z250). The specimens were re-thermocycled (1000×), sealed with nail varnish, stained with 0.5% basic fuchsin, sectioned mesiodistally and photographed digitally. The extent of dye penetration was measured by image analysis software (ImageJ) for both bur-finished and air-abraded surfaces at resin-tooth and resin-resin interfaces. The data were analyzed statistically. Results: BeautiBond exhibited the most microleakage at every site. Irrespective of adhesive and initial composite type, air-abrasion showed less microleakage except for BeautiBond. The type of initial repaired restorative material did not affect the microleakage. BeautiBond adhesive may not be preferred in resin composite repair in terms of microleakage prevention. Conclusions: Surface treatment with air-abrasion produced the lowest microleakage scores, independent of the adhesive systems and the pre-existing resin composite type. Pre-existing composite type does not affect the microleakage issue. All-in-one adhesive resin (BeautiBond) may not be preferred in resin composite repair in terms of microleakage prevention. PMID:25713491

  4. DYLOS DC110

    EPA Science Inventory

    The Dylos DC1100 air quality monitor measures particulate matter (PM) to provide a continuous assessment of indoor air quality. The unit counts particles in two size ranges: large and small. According to the manufacturer, large particles have diameters between 2.5 and 10 micromet...

  5. DC arc weld starter

    DOEpatents

    Campiotti, Richard H.; Hopwood, James E.

    1990-01-01

    A system for starting an arc for welding uses three DC power supplies, a high voltage supply for initiating the arc, an intermediate voltage supply for sustaining the arc, and a low voltage welding supply directly connected across the gap after the high voltage supply is disconnected.

  6. Chromatography resin support

    DOEpatents

    Dobos, James G.

    2002-01-01

    An apparatus and method of using an improved chromatography resin support is disclosed. The chromatography support platform is provided by a stainless steel hollow cylinder adapted for being inserted into a chromatography column. An exterior wall of the stainless steel cylinder defines a groove for carrying therein an "O"-ring. The upper surface of the stainless steel column is covered by a fine stainless steel mesh welded to the edges of the stainless steel cylinder. When placed upon a receiving ledge defined within a chromatography column, the "O"-ring provides a fluid tight seal with the inner edge wall of the chromatography cylinder. The stainless steel mesh supports the chromatography matrix and provides a back flushable support which is economical and simple to construct.

  7. Indirect resin composites

    PubMed Central

    Nandini, Suresh

    2010-01-01

    Aesthetic dentistry continues to evolve through innovations in bonding agents, restorative materials, and conservative preparation techniques. The use of direct composite restoration in posterior teeth is limited to relatively small cavities due to polymerization stresses. Indirect composites offer an esthetic alternative to ceramics for posterior teeth. This review article focuses on the material aspect of the newer generation of composites. This review was based on a PubMed database search which we limited to peer-reviewed articles in English that were published between 1990 and 2010 in dental journals. The key words used were ‘indirect resin composites,’ composite inlays,’ and ‘fiber-reinforced composites.’ PMID:21217945

  8. DC-DC powering for the CMS pixel upgrade

    NASA Astrophysics Data System (ADS)

    Feld, Lutz; Fleck, Martin; Friedrichs, Marcel; Hensch, Richard; Karpinski, Waclaw; Klein, Katja; Rittich, David; Sammet, Jan; Wlochal, Michael

    2013-12-01

    The CMS experiment plans to replace its silicon pixel detector with a new one with improved rate capability and an additional detection layer at the end of 2016. In order to cope with the increased number of detector modules the new pixel detector will be powered via DC-DC converters close to the sensitive detector volume. This paper reviews the DC-DC powering scheme and reports on the ongoing R&D program to develop converters for the pixel upgrade. Design choices are discussed and results from the electrical and thermal characterisation of converter prototypes are shown. An emphasis is put on system tests with up to 24 converters. The performance of pixel modules powered by DC-DC converters is compared to conventional powering. The integration of the DC-DC powering scheme into the pixel detector is described and system design issues are reviewed.

  9. Regulated dc-to-dc converter features low power drain

    NASA Technical Reports Server (NTRS)

    Thornwall, J.

    1968-01-01

    A regulated dc-to-dc converter requires negligible standby power for the operation of critical electronic equipment. The main operating circuitry consumes power intermittently according to load conditions, rather than constantly.

  10. 21 CFR 178.3930 - Terpene resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Terpene resins. 178.3930 Section 178.3930 Food and... and Production Aids § 178.3930 Terpene resins. The terpene resins identified in paragraph (a) of this... the terpene resins identified in paragraph (b) of this section may be safely used as components...

  11. 21 CFR 178.3930 - Terpene resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Terpene resins. 178.3930 Section 178.3930 Food and... and Production Aids § 178.3930 Terpene resins. The terpene resins identified in paragraph (a) of this... the terpene resins identified in paragraph (b) of this section may be safely used as components...

  12. 21 CFR 178.3930 - Terpene resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Terpene resins. 178.3930 Section 178.3930 Food and... and Production Aids § 178.3930 Terpene resins. The terpene resins identified in paragraph (a) of this... the terpene resins identified in paragraph (b) of this section may be safely used as components...

  13. 21 CFR 178.3930 - Terpene resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Terpene resins. 178.3930 Section 178.3930 Food and... and Production Aids § 178.3930 Terpene resins. The terpene resins identified in paragraph (a) of this... the terpene resins identified in paragraph (b) of this section may be safely used as components...

  14. 21 CFR 178.3930 - Terpene resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Terpene resins. 178.3930 Section 178.3930 Food and... Terpene resins. The terpene resins identified in paragraph (a) of this section may be safely used as components of polypropylene film intended for use in contact with food, and the terpene resins identified...

  15. Resin polymerization problems--are they caused by resin curing lights, resin formulations, or both?

    PubMed

    Christensen, R P; Palmer, T M; Ploeger, B J; Yost, M P

    1999-01-01

    Negative effects of rapid, high-intensity resin curing have been predicted for both argon lasers and plasma-arc curing lights. To address these questions, six different resin restorative materials were cured with 14 different resin curing lights representing differences in intensities ranging from 400 mW/cm2 to 1,900 mW/cm2; delivery modes using constant, ramped, and stepped methods; cure times ranging from 1 second to 40 seconds; and spot sizes of 6.7 mm to 10.9 mm. Two lasers, five plasma-arc lights, and seven halogen lights were used. Shrinkage, modulus, heat generation, strain, and physical changes on the teeth and resins during strain testing were documented. Results showed effects associated with lights were not statistically significant, but resin formulation was highly significant. Microfill resins had the least shrinkage and the lowest modulus. An autocure resin had shrinkage and modulus as high as or higher than the light-cured hybrid resins. Lasers and plasma-arc lights produced the highest heat increases on the surface (up to 21 degrees C) and within the resin restorations (up to 14 degrees C), and the halogen lights produced the most heat within the pulp chamber (up to 2 degrees C). Strain within the tooth was least with Heliomolar and greatest with Z100 Restorative and BISFIL II autocure resin. Clinical effects of strain relief were evident as white lines at the tooth-resin interface and cracks in enamel adjacent to the margins. This work implicates resin formulation, rather than light type or curing mode, as the important factor in polymerization problems. Lower light intensity and use of ramped and stepped curing modes did not provide significant lowering of shrinkage, modulus, or strain, and did not prevent enamel cracking adjacent to margins and formation of "white line" defects at the margins. Until materials with lower shrinkage and modulus are available, use of low-viscosity surface sealants as a final step in resin placement is suggested to

  16. Flammability screening tests of resins

    NASA Technical Reports Server (NTRS)

    Arhart, R. W.; Farrar, D. G.; Hughes, B. M.

    1979-01-01

    Selected flammability characteristics of glass cloth laminates of thermosetting resins are evaluated. A protocol for the evaluation of the flammability hazards presented by glass cloth laminates of thermosetting resins and the usefulness of that protocol with two laminates are presented. The glass laminates of an epoxy resin, M-751 are evaluated for: (1) determination of smoke generation from the laminates; (2) analysis of products of oxidative degradation of the laminates; (3) determination of minimum oxygen necessary to maintain flaming oxidation; (4) evaluation of toxicological hazards.

  17. Grafted methylenediphosphonate ion exchange resins

    DOEpatents

    Trochimcznk, A.W.; Gatrone, R.C.; Alexandratos, S.; Horwitz, E.P.

    1997-04-08

    An ion exchange resin is disclosed that is comprised of an insoluble copolymer onto which are grafted pendent groups that provide 1.0 to about 10 mmol/g dry weight phosphorus. The pendent groups have the formula as shown in the patent wherein R is hydrogen, a cation or mixtures thereof; and R{sup 1} is hydrogen or an C{sub 1}-C{sub 2} alkyl group. The resin also contains zero to about 5 mmol/g dry weight of pendent aromatic sulfonate groups. Processes for making and using an ion exchange resin are also disclosed.

  18. Grafted methylenediphosphonate ion exchange resins

    DOEpatents

    Trochimcznk, Andrzej W.; Gatrone, Ralph C.; Alexandratos, Spiro; Horwitz, E. Philip

    1997-01-01

    An ion exchange resin is disclosed that is comprised of an insoluble copolymer onto which are grafted pendent groups that provide 1.0 to about 10 mmol/g dry weight phosphorous. The pendent groups have the formula ##STR1## wherein R is hydrogen, a cation or mixtures thereof; and R.sup.1 is hydrogen or an C.sub.1 -C.sub.2 alkyl group. The resin also contains zero to about 5 mmol/g dry weight of pendent aromatic sulfonate groups. Processes for making and using an ion exchange resin are also disclosed.

  19. Grafted methylenediphosphonate ion exchange resins

    DOEpatents

    Trochimcznk, Andrzej W.; Gatrone, Ralph C.; Alexandratos, Spiro; Horwitz, E. Philip

    1998-01-27

    An ion exchange resin is disclosed that is comprised of an insoluble copolymer onto which are grafted pendent groups that provide 1.0 to about 10 mmol/g dry weight phosphorous. The pendent groups have the formula ##STR1## wherein R is hydrogen, a cation or mixtures thereof; and R.sup.1 is hydrogen or an C.sub.1 -C.sub.2 alkyl group. The resin also contains zero to about 5 mmol/g dry weight of pendent aromatic sulfonate groups. Processes for making and using an ion exchange-resin are also disclosed.

  20. Resin/graphite fiber composites

    NASA Technical Reports Server (NTRS)

    Cavano, P. J.; Jones, R. J.; Vaughan, R. W.

    1972-01-01

    High temperature resin matrices suitable for use in advanced graphite fiber composites for jet engine applications were evaluated. A series of planned, sequential screening experiments with resin systems in composite form were performed to reduce the number of candidates to a single A-type polyimide resin that repetitively produced void-free, high strength and modulus composites acceptable for use in the 550 F range for 1000 hours. An optimized processing procedure was established for this system. Extensive mechanical property studies characterized this single system, at room temperature, 500 F, 550 F and 600 F, for various exposure times.

  1. Early Oscillation Detection for DC/DC Converter Fault Diagnosis

    NASA Technical Reports Server (NTRS)

    Wang, Bright L.

    2011-01-01

    The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.

  2. DC current monitor

    NASA Technical Reports Server (NTRS)

    Canter, Stanley (Inventor)

    1991-01-01

    A non-intrusive DC current monitor is presented which emulates the theoretical operation of an AC transformer. A conductor, carrying the current to be measured, acts as the primary of a DC current transformer. This current is passed through the center of a secondary coil, and core positioned thereabout, and produces a magnetic flux which induces a current in the secondary proportional to the current flowing in the primary. Means are provided to periodically reset the transformer core such that the measurement inaccuracies associated with core saturation are obviated. A reset current is caused to periodically flow through the secondary coil which produces a magnetic flux oppositely polarized to the flux created by the current in the primary, thus allowing ongoing measurements to be made.

  3. Liquid monobenzoxazine based resin system

    DOEpatents

    Tietze, Roger; Nguyen, Yen-Loan; Bryant, Mark

    2014-10-07

    The present invention provides a liquid resin system including a liquid monobenzoxazine monomer and a non-glycidyl epoxy compound, wherein the weight ratio of the monobenzoxazine monomer to the non-glycidyl epoxy compound is in a range of about 25:75 to about 60:40. The liquid resin system exhibits a low viscosity and exceptional stability over an extended period of time making its use in a variety of composite manufacturing methods highly advantageous.

  4. Regenerating Water-Sterilizing Resins

    NASA Technical Reports Server (NTRS)

    Colombo, G. V.; Putnam, D. F.

    1982-01-01

    Iodine-dispensing resin can be regenerated after iodine content has been depleted, without being removed from water system. Resin is used to make water potable by killing bacteria, fungi, and viruses. Regeneration technique may be come basis of water purifier for very long space missions. Enough crystalline iodine for multiple regenerations during mission can be stored in one small cartridge. Cartridge could be inserted in waterline as necessary on signal from iodine monitor or timer.

  5. Maleimide Functionalized Siloxane Resins

    SciTech Connect

    Loy, D.A.; Shaltout, R.M.

    1999-04-01

    Polyorganosiloxanes are a commercially important class of compounds. They exhibit many important properties, including very low glass transition temperatures, making them useful over a wide temperature range. In practice, the polysiloxane polymer is often mixed with a filler material to help improve its mechanical properties. An alternative method for increasing polymer mechanical strength is through the incorporation of certain substituents on the polymer backbone. Hard substituents such as carbonates and imides generally result in improved mechanical properties of polysiloxanes. In this paper, we present the preparation of novel polysiloxane resins modified with hard maleimide substituents. Protected ethoxysilyl-substituted propyl-maleimides were prepared. The maleimide substituent was protected with a furanyl group and the monomer polymerized under aqueous acidic conditions. At elevated temperatures (>120 C), the polymer undergoes retro Diels-Alder reaction with release of foran (Equation 1). The deprotected polymer can then be selectively crosslinked by a forward Diels-Alder reaction (in the presence of a co-reactant having two or more dime functionalities).

  6. The effect of biobased plastic resins containing chichen feather fibers on the growth and flowering of Begonia boliviensis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to evaluate growth and flowering of Begoniaboliviensis A. DC. 'Bonfire' when grown in medium mixed with pellets made from biobased plastic resins containing chicken feather fibers. We also analyzed macro- and macro-elements in soil and leaf tissues during different develope...

  7. Curing behavior and reaction kinetics of binder resins for 3D-printing investigated by dielectric analysis (DEA)

    NASA Astrophysics Data System (ADS)

    Möginger, B.; Kehret, L.; Hausnerova, B.; Steinhaus, J.

    2016-05-01

    3D-Printing is an efficient method in the field of additive manufacturing. In order to optimize the properties of manufactured parts it is essential to adapt the curing behavior of the resin systems with respect to the requirements. Thus, effects of resin composition, e.g. due to different additives such as thickener and curing agents, on the curing behavior have to be known. As the resin transfers from a liquid to a solid glass the time dependent ion viscosity was measured using DEA with flat IDEX sensors. This allows for a sensitive measurement of resin changes as the ion viscosity changes two to four decades. The investigated resin systems are based on the monomers styrene and HEMA. To account for the effects of copolymerization in the calculation of the reaction kinetics it was assumed that the reaction can be considered as a homo-polymerization having a reaction order n≠1. Then the measured ion viscosity curves are fitted with the solution of the reactions kinetics - the time dependent degree of conversion (DC-function) - for times exceeding the initiation phase representing the primary curing. The measured ion viscosity curves can nicely be fitted with the DC-function and the determined fit parameters distinguish distinctly between the investigated resin compositions.

  8. Effect of Light Intensity on the Degree of Conversion of Dual-cured Resin Cement at Different Depths with the use of Translucent Fiber Posts

    PubMed Central

    Bahari, Mahmoud; Savadi Oskoee, Siavash; Kimyai, Soodabeh; Mohammadi, Narmin; Saati Khosroshahi, Elmira

    2014-01-01

    Objectives: To evaluate the effect of different light intensities on the degree of conversion (DC) of dual-cured resin cement at different depths of translucent fiber posts. Materials and Methods: Thirty translucent fiber posts were randomly assigned into three (n=10) groups. They were cemented in the simulated canal spaces using Duo-Link dual-cured resin cement. The cement was light-cured under 600, 800 and 1100 mW/cm2 light intensities for 40 seconds. DC of the resin cement was calculated at cervical, middle and apical thirds using the spectra of FT-Raman spectrometer. Data were analyzed by repeated measurement ANOVA and Tukey’s post hoc tests (α=0.05). Results: In all the groups, the least DC was obtained at the apical region. There were no significant differences in the DC with different light intensities between the cervical and middle regions (p>0.05). However, in the apical region, the DC in both 800 and 1100 mw/cm2 was similar (p>0.05), but greater with 600 mW/cm2 light intensity (p=0.02 and p<0.001, respectively). Conclusion: In comparison with the light intensity of 600 mW/cm2, the light intensity of 800 mW/cm2 significantly increased the DC of dual-cured resin cement in the apical region. However, DC was not significantly different between 800 and 1100 mw/cm2 light intensities. If the resin cement, especially in the apical areas is not sufficiently cured, microleakage might increase and post retention might be jeopardized. In comparison with 600 mW/cm2 light intensity, 800 mW/cm2 significantly increases DC at the apical third that might be clinically beneficial. PMID:25628659

  9. Auxiliary resonant DC tank converter

    DOEpatents

    Peng, Fang Z.

    2000-01-01

    An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.

  10. Low Melt Viscosity Resins for Resin Transfer Molding

    NASA Technical Reports Server (NTRS)

    Harris, Frank W.

    2002-01-01

    In recent years, resin transfer molding (RTM) has become one of the methods of choice for high performance composites. Its cost effectiveness and ease of fabrication are major advantages of RTM. RTM process usually requires resins with very low melt viscosity (less than 10 Poise). The optimum RTM resins also need to display high thennal-oxidative stability, high glass transition temperature (T(sub g)), and good toughness. The traditional PMR-type polyimides (e.g. PMR-15) do not fit this requirement, because the viscosities are too high and the nadic endcap cures too fast. High T(sub g), low-melt viscosity resins are highly desirable for aerospace applications and NASA s Reusable Launch Vehicle (RLV) program. The objective of this work is to prepare low-melt viscosity polyimide resins for RTM or resin film infusion (RFI) processes. The approach involves the synthesis of phenylethynyl-terminated imide oligomers. These materials have been designed to minimize their melt viscosity so that they can be readily processed. During the cure, the oligomers undergo both chain extension and crosslinking via the thermal polymerization of the phenylethynyl groups. The Phenylethynyl endcap is preferred over the nadic group due to its high curing temperature, which provides broader processing windows. This work involved the synthesis and polymerization of oligomers containing zig-zag backbones and twisted biphenyl structures. Some A-B type precursors which possessed both nitro and anhydride functionality, or both nitro and amine functionality, were also synthesized in order to obtain the well defined oligomers. The resulting zig-zag structured oligomers were then end-capped with 4-phenylethynylphthalic anhydride (PEPA) for further cure. The properties of these novel imide oligomers are evaluated.

  11. Improved DC Gun Insulator

    SciTech Connect

    M.L. Neubauer, K.B. Beard, R. Sah, C. Hernandez-Garcia, G. Neil

    2009-05-01

    Many user facilities such as synchrotron light sources and free electron lasers require accelerating structures that support electric fields of 10-100 MV/m, especially at the start of the accelerator chain where ceramic insulators are used for very high gradient DC guns. These insulators are difficult to manufacture, require long commissioning times, and have poor reliability, in part because energetic electrons bury themselves in the ceramic, creating a buildup of charge and causing eventual puncture. A novel ceramic manufacturing process is proposed. It will incorporate bulk resistivity in the region where it is needed to bleed off accumulated charge caused by highly energetic electrons. This process will be optimized to provide an appropriate gradient in bulk resistivity from the vacuum side to the air side of the HV standoff ceramic cylinder. A computer model will be used to determine the optimum cylinder dimensions and required resistivity gradient for an example RF gun application. A ceramic material example with resistivity gradient appropriate for use as a DC gun insulator will be fabricated by glazing using doping compounds and tested.

  12. Analysis of self-oscillating dc-to-dc converters

    NASA Technical Reports Server (NTRS)

    Burger, P.

    1974-01-01

    The basic operational characteristics of dc-to-dc converters are analyzed along with the basic physical characteristics of power converters. A simple class of dc-to-dc power converters are chosen which could satisfy any set of operating requirements, and three different controlling methods in this class are described in detail. Necessary conditions for the stability of these converters are measured through analog computer simulation whose curves are related to other operational characteristics, such as ripple and regulation. Further research is suggested for the solution of absolute stability and efficient physical design of this class of power converters.

  13. High performance dc-dc conversion with voltage multipliers

    NASA Technical Reports Server (NTRS)

    Harrigill, W. T.; Myers, I. T.

    1974-01-01

    The voltage multipliers using capacitors and diodes first developed by Cockcroft and Walton in 1932 were reexamined in terms of state of the art fast switching transistors and diodes, and high energy density capacitors. Because of component improvements, the voltage multiplier, used without a transformer, now appears superior in weight to systems now in use for dc-dc conversion. An experimental 100-watt 1000-volt dc-dc converter operating at 100 kHz was built, with a component weight of about 1 kg/kW. Calculated and measured values of output voltage and efficiency agreed within experimental error.

  14. Multiple high voltage output DC-to-DC power converter

    NASA Technical Reports Server (NTRS)

    Cronin, Donald L. (Inventor); Farber, Bertrand F. (Inventor); Gehm, Hartmut K. (Inventor); Goldin, Daniel S. (Inventor)

    1977-01-01

    Disclosed is a multiple output DC-to-DC converter. The DC input power is filtered and passed through a chopper preregulator. The chopper output is then passed through a current source inverter controlled by a squarewave generator. The resultant AC is passed through the primary winding of a transformer, with high voltages induced in a plurality of secondary windings. The high voltage secondary outputs are each solid-state rectified for passage to individual output loads. Multiple feedback loops control the operation of the chopper preregulator, one being responsive to the current through the primary winding and another responsive to the DC voltage level at a selected output.

  15. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E.P.; Alexandratos, S.D.; Gatrone, R.C.; Chiarizia, R.

    1994-01-25

    An ion exchange resin is described for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene. 9 figures.

  16. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E.P.; Alexandratos, S.D.; Gatrone, R.C.; Chiarizia, R.

    1996-07-23

    An ion exchange resin is described for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene. 10 figs.

  17. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E. Philip; Alexandratos, Spiro D.; Gatrone, Ralph C.; Chiarizia, Ronato

    1996-01-01

    An ion exchange resin for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene.

  18. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E. Philip; Alexandratos, Spiro D.; Gatrone, Ralph C.; Chiarizia, Ronato

    1994-01-01

    An ion exchange resin for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene disphosphonic acid with styrene, acrylonitrile and divinylbenzene.

  19. Soluble high molecular weight polyimide resins

    NASA Technical Reports Server (NTRS)

    Jones, R. J.; Lubowitz, H. R.

    1970-01-01

    High molecular weight polyimide resins have greater than 20 percent /by weight/ solubility in polar organic solvents. They permit fabrication into films, fibers, coatings, reinforced composite, and adhesive product forms. Characterization properties for one typical polyimide resin are given.

  20. Degree of conversion and leached monomers of urethane dimethacrylate-hydroxypropyl methacrylate-based dental resin systems.

    PubMed

    Zhang, Meng; Puska, Mervi A; Botelho, Michael G; Säilynoja, Eija S; Matinlinna, Jukka P

    2016-01-01

    The degree of conversion (DC) and monomer leaching of three experimental urethane dimethacrylate (UEDMA)-hydroxypropyl methacrylate (HPMA)-based resin systems were studied. Three experimental resins (E1: 70.6 wt% UEDMA + 27.4 wt% HPMA, E2: 80.6 wt% UEDMA + 17.4 wt% HPMA, E3: 90.6 wt% UEDMA + 7.4 wt% HPMA) and one control resin [C: 70.6 wt% bis-phenol A glycidyl methacrylate (bis-GMA) + 27.4 wt% methyl methacrylate (MMA)] were prepared. For the DC test, cylindrical specimens [1.5 mm (h) × 6 mm (d)] were scanned with an ATR-FTIR instrument before and after light-curing (n = 5). For the monomer leaching test, block-shaped specimens [5.67 mm (l) × 2.00 mm (w) × 2.00 mm (h)] were light-cured (n = 6), stored in a 75% ethanol:water solution for 3 days, and then analyzed with HPLC. The UEDMA-HPMA-based experimental groups showed higher DC (62-78%) than the bis-GMA-MMA-based control group (58-66%), and the DC decreased as the UEDMA content increased (P < 0.05). Amongst the four groups, E3 exhibited the lowest leaching of both mono methacrylate (0.1% HPMA) and dimethacrylate (<0.043% UEDMA) monomers after 30 or 40 s of curing. The UEDMA-HPMA-based resins, therefore, exhibited higher DC and less monomer leaching compared to the bis-GMA-MMA-based resin. (J Oral Sci 58, 15-22, 2016). PMID:27021535

  1. Method for loading resin beds

    DOEpatents

    Notz, Karl J.; Rainey, Robert H.; Greene, Charles W.; Shockley, William E.

    1978-01-01

    An improved method of preparing nuclear reactor fuel by carbonizing a uranium loaded cation exchange resin provided by contacting a H.sup.+ loaded resin with a uranyl nitrate solution deficient in nitrate, comprises providing the nitrate deficient solution by a method comprising the steps of reacting in a reaction zone maintained between about 145.degree.-200.degree. C, a first aqueous component comprising a uranyl nitrate solution having a boiling point of at least 145.degree. C with a second aqueous component to provide a gaseous phase containing HNO.sub.3 and a reaction product comprising an aqueous uranyl nitrate solution deficient in nitrate.

  2. A DC Transformer

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.; Ihlefeld, Curtis M.; Starr, Stanley O.

    2013-01-01

    A component level dc transformer is described in which no alternating currents or voltages are present. It operates by combining features of a homopolar motor and a homopolar generator, both de devices, such that the output voltage of a de power supply can be stepped up (or down) with a corresponding step down (or up) in current. The basic theory for this device is developed, performance predictions are made, and the results from a small prototype are presented. Based on demonstrated technology in the literature, this de transformer should be scalable to low megawatt levels, but it is more suited to high current than high voltage applications. Significant development would be required before it could achieve the kilovolt levels needed for de power transmission.

  3. A Plasma-Based DC-DC Electrical Transformer

    NASA Astrophysics Data System (ADS)

    Nebel, Richard; Finn, John

    2013-10-01

    Previous work has indicated that it may be possible to make DC-DC electrical transformers using plasmas. The mechanism is an MHD electromagnetic relaxation process induced by helical electrodes. This process is now being tested on the Bismark device at Tibbar Technologies.

  4. Efficient Design in a DC to DC Converter Unit

    NASA Technical Reports Server (NTRS)

    Bruemmer, Joel E.; Williams, Fitch R.; Schmitz, Gregory V.

    2002-01-01

    Space Flight hardware requires high power conversion efficiencies due to limited power availability and weight penalties of cooling systems. The International Space Station (ISS) Electric Power System (EPS) DC-DC Converter Unit (DDCU) power converter is no exception. This paper explores the design methods and tradeoffs that were utilized to accomplish high efficiency in the DDCU. An isolating DC to DC converter was selected for the ISS power system because of requirements for separate primary and secondary grounds and for a well-regulated secondary output voltage derived from a widely varying input voltage. A flyback-current-fed push-pull topology or improved Weinberg circuit was chosen for this converter because of its potential for high efficiency and reliability. To enhance efficiency, a non-dissipative snubber circuit for the very-low-Rds-on Field Effect Transistors (FETs) was utilized, redistributing the energy that could be wasted during the switching cycle of the power FETs. A unique, low-impedance connection system was utilized to improve contact resistance over a bolted connection. For improved consistency in performance and to lower internal wiring inductance and losses a planar bus system is employed. All of these choices contributed to the design of a 6.25 KW regulated dc to dc converter that is 95 percent efficient. The methodology used in the design of this DC to DC Converter Unit may be directly applicable to other systems that require a conservative approach to efficient power conversion and distribution.

  5. Dc-To-Dc Converter Uses Reverse Conduction Of MOSFET's

    NASA Technical Reports Server (NTRS)

    Gruber, Robert P.; Gott, Robert W.

    1991-01-01

    In modified high-power, phase-controlled, full-bridge, pulse-width-modulated dc-to-dc converters, switching devices power metal oxide/semiconductor field-effect transistors (MOSFET's). Decreases dissipation of power during switching by eliminating approximately 0.7-V forward voltage drop in anti-parallel diodes. Energy-conversion efficiency increased.

  6. 21 CFR 177.1550 - Perfluorocarbon resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... Perfluorocarbon resins can be identified by their characteristic infrared spectra. (2) Melt-viscosity. (i) The per-fluoro-carbon resins identified in paragraph (a)(1) of this section shall have a melt viscosity of not... viscosity of the perfluorocarbon resins identified in paragraph (a)(1) of this section shall not vary...

  7. 21 CFR 177.1550 - Perfluorocarbon resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... Perfluorocarbon resins can be identified by their characteristic infrared spectra. (2) Melt-viscosity. (i) The per-fluoro-carbon resins identified in paragraph (a)(1) of this section shall have a melt viscosity of not... viscosity of the perfluorocarbon resins identified in paragraph (a)(1) of this section shall not vary...

  8. 21 CFR 177.1550 - Perfluorocarbon resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    .... Perfluorocarbon resins can be identified by their characteristic infrared spectra. (2) Melt-viscosity. (i) The per-fluoro-carbon resins identified in paragraph (a)(1) of this section shall have a melt viscosity of not... viscosity of the perfluorocarbon resins identified in paragraph (a)(1) of this section shall not vary...

  9. Method for removing contaminants from plastic resin

    DOEpatents

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2008-12-30

    A method for removing contaminants from synthetic resin material containers using a first organic solvent system and a second carbon dioxide system. The organic solvent is utilized for removing the contaminants from the synthetic resin material and the carbon dioxide is used to separate any residual organic solvent from the synthetic resin material.

  10. Method of removing contaminants from plastic resins

    DOEpatents

    Bohnert,George W.; Hand,Thomas E.; Delaurentiis,Gary M.

    2007-08-07

    A method for removing contaminants from synthetic resin material containers using a first organic solvent system and a second carbon dioxide system. The organic solvent is utilized for removing the contaminants from the synthetic resin material and the carbon dioxide is used to separate any residual organic solvent from the synthetic resin material.

  11. Method of removing contaminants from plastic resins

    DOEpatents

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2008-11-18

    A method for removing contaminants from synthetic resin material containers using a first organic solvent system and a second carbon dioxide system. The organic solvent is utilized for removing the contaminants from the synthetic resin material and the carbon dioxide is used to separate any residual organic solvent from the synthetic resin material.

  12. 21 CFR 172.280 - Terpene resin.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Terpene resin. 172.280 Section 172.280 Food and... Terpene resin. The food additive terpene resin may be safely used in accordance with the following prescribed conditions: (a) The food additive is the betapinene polymer obtained by polymerizing...

  13. 21 CFR 172.280 - Terpene resin.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Terpene resin. 172.280 Section 172.280 Food and..., Films and Related Substances § 172.280 Terpene resin. The food additive terpene resin may be safely used... polymer obtained by polymerizing terpene hydrocarbons derived from wood. It has a softening point of...

  14. 21 CFR 172.280 - Terpene resin.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Terpene resin. 172.280 Section 172.280 Food and..., Films and Related Substances § 172.280 Terpene resin. The food additive terpene resin may be safely used... polymer obtained by polymerizing terpene hydrocarbons derived from wood. It has a softening point of...

  15. 21 CFR 172.280 - Terpene resin.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Terpene resin. 172.280 Section 172.280 Food and..., Films and Related Substances § 172.280 Terpene resin. The food additive terpene resin may be safely used... polymer obtained by polymerizing terpene hydrocarbons derived from wood. It has a softening point of...

  16. 21 CFR 172.280 - Terpene resin.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Terpene resin. 172.280 Section 172.280 Food and..., Films and Related Substances § 172.280 Terpene resin. The food additive terpene resin may be safely used... polymer obtained by polymerizing terpene hydrocarbons derived from wood. It has a softening point of...

  17. Early Oscillation Detection Technique for Hybrid DC/DC Converters

    NASA Technical Reports Server (NTRS)

    Wang, Bright L.

    2011-01-01

    Oscillation or instability is a situation that must be avoided for reliable hybrid DC/DC converters. A real-time electronics measurement technique was developed to detect catastrophic oscillations at early stages for hybrid DC/DC converters. It is capable of identifying low-level oscillation and determining the degree of the oscillation at a unique frequency for every individual model of the converters without disturbing their normal operations. This technique is specially developed for space-used hybrid DC/DC converters, but it is also suitable for most of commercial and military switching-mode power supplies. This is a weak-electronic-signal detection technique to detect hybrid DC/DC converter oscillation presented as a specific noise signal at power input pins. It is based on principles of feedback control loop oscillation and RF signal modulations, and is realized by using signal power spectral analysis. On the power spectrum, a channel power amplitude at characteristic frequency (CPcf) and a channel power amplitude at switching frequency (CPsw) are chosen as oscillation level indicators. If the converter is stable, the CPcf is a very small pulse and the CPsw is a larger, clear, single pulse. At early stage of oscillation, the CPcf increases to a certain level and the CPsw shows a small pair of sideband pulses around it. If the converter oscillates, the CPcf reaches to a higher level and the CPsw shows more high-level sideband pulses. A comprehensive stability index (CSI) is adopted as a quantitative measure to accurately assign a degree of stability to a specific DC/DC converter. The CSI is a ratio of normal and abnormal power spectral density, and can be calculated using specified and measured CPcf and CPsw data. The novel and unique feature of this technique is the use of power channel amplitudes at characteristic frequency and switching frequency to evaluate stability and identify oscillations at an early stage without interfering with a DC/DC converter s

  18. Process for curing bismaleimide resins

    NASA Technical Reports Server (NTRS)

    Parker, John A. (Inventor); OTHY S.imides alone. (Inventor)

    1986-01-01

    This invention relates to vinyl pyridine group containing compounds and oligomers, their advantageous copolymerization with bismaleimide resins, and the formation of reinforced composites based on these copolymers. When vinyl pyridines including vinyl stilbazole materials and vinyl styrylpyridine oligomer materials are admixed with bismaleimides and cured to form copolymers the cure temperatures of the copolymers are substantially below the cure temperatures of the bismaleimides alone.

  19. Synthesis of improved phenolic resins

    NASA Technical Reports Server (NTRS)

    Delano, C. B.; Mcleod, A. H.

    1979-01-01

    Twenty seven addition cured phenolic resin compositions were prepared and tested for their ability to give char residues comparable to state-of-the-art phenolic resins. Cyanate, epoxy, allyl, acrylate, methacrylate and ethynyl derivatized phenolic oligomers were investigated. The novolac-cyanate and propargyl-novolac resins provided anaerobic char yields at 800 C of 58 percent. A 59 percent char yield was obtained from modified epoxy novolacs. A phosphonitrilic derivative was found to be effective as an additive for increasing char yields. The novolac-cyanate, epoxy-novolac and methacrylate-epoxy-novolac systems were investigated as composite matrices with Thornel 300 graphite fiber. All three resins showed good potential as composite matrices. The free radical cured methacrylate-epoxy-novolac graphite composite provided short beam shear strengths at room temperature of 93.3 MPa (13.5 ksi). The novolac-cyanate graphite composite produced a short beam shear strength of 74 MPa (10.7 ksi) and flexural strength of 1302 MPa (189 ksi) at 177 C. Air heat aging of the novolac-cyanate and epoxy novolac based composites for 12 weeks at 204 C showed good property retention.

  20. 76 FR 13926 - Airworthiness Directives; The Boeing Company Model DC-8-11, DC-8-12, DC-8-21, DC-8-31, DC-8-32...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-15

    ... required by AD 2008-25-05, Amendment 39-15763 (73 FR 78936, December 24, 2008), for Principal Structural... Policies and Procedures (44 FR 11034, February 26, 1979), and 3. Will not have a significant economic...-8-21, DC-8-31, DC-8-32, DC-8-33, DC-8-41, DC-8-42, DC-8-43, DC-8-51, DC-8-52, DC-8-53,......

  1. Fiber reinforced composite resin systems.

    PubMed

    Giordano, R

    2000-01-01

    The Targis/Vectris and Sculpture/FibreKor systems were devised to create a translucent maximally reinforced resin framework for fabrication of crowns, bridges, inlays, and onlays. These materials are esthetic, have translucency similar to castable glass-ceramics such as OPC and Empress, and have fits that are reported to be acceptable in clinical and laboratory trials. These restorations rely on proper bonding to the remaining tooth structure; therefore, careful attention to detail must be paid to this part of the procedure. Cementation procedures should involve silane treatment of the cleaned abraded internal restoration surface, application of bonding agent to the restoration as well as the etched/primed tooth, and finally use of a composite resin. Each manufacturer has a recommended system which has been tested for success with its resin system. These fiber reinforced resins are somewhat different than classical composites, so not all cementation systems will necessarily work with them. Polishing of the restoration can be accomplished using diamond or alumina impregnated rubber wheels followed by diamond paste. The glass fibers can pose a health risk. They are small enough to be inhaled and deposited in the lungs, resulting in a silicosis-type problem. Therefore, if fibers are exposed and ground on, it is extremely important to wear a mask. Also, the fibers can be a skin irritant, so gloves also should be worn. If the fibers become exposed intraorally, they can cause gingival inflammation and may attract plaque. The fibers should be covered with additional composite resin. If this cannot be accomplished, the restoration should be replaced. The bulk of these restorations are formed using a particulate filled resin, similar in structure to conventional composite resins. Therefore, concerns as to wear resistance, color stability, excessive expansion/contraction, and sensitivity remain until these materials are proven in long-term clinical trials. They do hold the

  2. Oxygen index tests of thermosetting resins

    NASA Technical Reports Server (NTRS)

    Gilwee, W. J., Jr.; Parker, J. A.; Kourtides, D. A.

    1980-01-01

    The flammability characteristics of nine thermosetting resins under evaluation for use in aircraft interiors are described. These resins were evaluated using the Oxygen Index (ASTM 2863) testing procedure. The test specimens consisted of both neat resin and glass reinforced resin. When testing glass-reinforced samples it was observed that Oxygen Index values varied inversely with resin content. Oxygen values were also obtained on specimens exposed to temperatures up to 300 C. All specimens experienced a decline in Oxygen Index when tested at an elevated temperature.

  3. Commercial Ion Exchange Resin Vitrification Studies

    SciTech Connect

    Cicero-Herman, C.A

    2002-06-28

    In the nuclear industry, ion exchange resins are used for purification of aqueous streams. The major contaminants of the resins are usually the radioactive materials that are removed from the aqueous streams. The use of the ion exchange resins creates a waste stream that can be very high in both organic and radioactive constituents. Therefore, disposal of the spent resin often becomes an economic problem because of the large volumes of resin produced and the relatively few technologies that are capable of economically stabilizing this waste. Vitrification of this waste stream presents a reasonable disposal alternative because of its inherent destruction capabilities, the volume reductions obtainable, and the durable product that it produces.

  4. Triple voltage dc-to-dc converter and method

    SciTech Connect

    Su, Gui-Jia

    2008-08-05

    A circuit and method of providing three dc voltage buses and transforming power between a low voltage dc converter and a high voltage dc converter, by coupling a primary dc power circuit and a secondary dc power circuit through an isolation transformer; providing the gating signals to power semiconductor switches in the primary and secondary circuits to control power flow between the primary and secondary circuits and by controlling a phase shift between the primary voltage and the secondary voltage. The primary dc power circuit and the secondary dc power circuit each further comprising at least two tank capacitances arranged in series as a tank leg, at least two resonant switching devices arranged in series with each other and arranged in parallel with the tank leg, and at least one voltage source arranged in parallel with the tank leg and the resonant switching devices, said resonant switching devices including power semiconductor switches that are operated by gating signals. Additional embodiments having a center-tapped battery on the low voltage side and a plurality of modules on both the low voltage side and the high voltage side are also disclosed for the purpose of reducing ripple current and for reducing the size of the components.

  5. Phenoxy resins containing pendent ethynyl groups

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M.; Jensen, B. J.; Havens, S. J.

    1984-01-01

    As part of an effort on tougher/solvent resistant matrix resins for composites, research was directed towards exploring methods to improve the solvent resistance of linear amorphous thermoplastics. Ethyl reactive groups were placed on the ends of oligomers and pendent along the polymer chain and subsequently thermally reacted to provide crosslinking and thus improvement in solvent resistance. This concept is extended to another thermoplastic, a phenoxy resin. A commercially available phenoxy resin (PKHH) was systematically modified by reaction of the pendent hydroxyl groups on the phenoxy resin with various amounts of 4-ethynylbenzoyl chloride. As the pendent ethynyl group content in the phenoxy resin increased, the cured resin exhibited a higher glass transition temperature, better solvent resistance and less flexibility. The solvent resistance was further improved by correcting a low molecular weight diethynyl compound, 2,2-bis(4-ethynylbenzoyloxy-4'-phenyl)propane, with a phenoxy resin containing pendent ethynyl groups.

  6. Bi-Directional DC-DC Converter for PHEV Applications

    SciTech Connect

    Abas Goodarzi

    2011-01-31

    Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.

  7. Piezometer completion report for borehold cluster sites DC-19, DC-20 and DC-22

    SciTech Connect

    Jackson, R.L.; Diediker, L.D.; Ledgerwood, R.K.; Veatch, M.D.

    1984-07-01

    This report describes the design and installation of multi-level piezometers at borehole cluster sites DC-19, DC-20 and DC-22. The network of borehole cluster sites will provide facilities for multi-level water-level monitoring across the RRL for piezometer baseline monitoring and for large-scale hydraulic stress testing. These groundwater-monitoring facilities were installed between August 1983 and March 1984. Three series of piezometer nests (A-, C- and D-series) were installed in nine hydrogeologic units (monitoring horizons) within the Columbia River Basalt Group at each borehole cluster site. In addition to the piezometer facilities, a B-series pumping well was installed at borehole cluster sites DC-20 and DC-22. The A-series piezometer nest monitors the basal Ringold sediments and the Rattlesnake Ridge interbed. The C-series piezometer nests monitors the six deepest horizons, which are in increasing depth, the Priest Rapids interflow. 21 refs., 6 figs., 14 tabs.

  8. Degree of conversion of different composite resins photo-activated with light-emitting diode and argon ion laser

    NASA Astrophysics Data System (ADS)

    Messias, A. M.; Galvão, M. R.; Boaventura, J. M. C.; Jacomassi, D. P.; Bernardi, M. I. B.; Bagnato, V. S.; Rastelli, A. N. S.; Andrade, M. F.

    2015-02-01

    This study evaluated the degree of conversion (DC%) of one experimental and different brands of composite resins light-cured by two light sources (one LED and one argon laser). The percentage of unreacted C = C was determined from the ratio of absorbance intensities of aliphatic C = C (peak at 1637 cm-1) against internal standards before and after curing: aromatic C-C (peak at 1610 cm-1) except for P90, where %C = C bonds was given for C-O-C (883 cm-1) and C-C (1257 cm-1). ANOVA and Tukey’s test revealed no statistically significant difference among Z350 (67.17), Z250 (69.52) and experimental (66.61  ±  2.03) with LED, just among them and Evolu-X (75.51) and P90 (32.05) that showed higher and lower DC%, respectively. For the argon laser, there were no differences among Z250 (70.67), Z350 (69.60), experimental (65.66) and Evolu-X (73, 37), however a significant difference was observed for P90 (36.80), which showed lowest DC%. The light sources showed similar DC%, however the main difference was observed regarding the composite resins. The lowest DC% was observed for the argon laser. P90 showed the lowest DC% for both light-curing sources.

  9. Bond performance of "Touch and Cure" adhesives on resin core systems.

    PubMed

    Kadowaki, Yoshitaka; Kakuda, Shinichi; Kawano, Shimpei; Katsumata, Aiichiro; Ting, Shihchun; Hoshika, Shuhei; Ikeda, Takatsumi; Tanaka, Toru; Carvalho, Ricardo Marinsde; Sano, Hidehiko

    2016-01-01

    The purpose of this study was to compare the micro-tensile bond strength (µTBS) of three resin core composites to dentin and to examine the bonded interface of the composites. One experimental TDK-03(TD) and, two commercial, DC core Automix One (DC) and Unifil core EM(UN) were used. Flat dentin surfaces of human molars were exposed using #600 SiC paper and bonded with the respective adhesive of each system. After bonding, the composites were built up on the surfaces and cured under two conditions: "light condition" or "dark condition". µTBSs (MPa) in the light condition were: TD; 60.02±17.08, DC; 38.21±13.70, and UN; 29.50±9.71; in the dark condition: TD; 54.62±17.11, DC; 8.40±4.81, and UN; 9.47±6.56. Dark curing negatively affected the bond strength of the two commercial resin-core materials. The experimental material was not affected by the curing conditions. PMID:27251993

  10. DC-Compensated Current Transformer.

    PubMed

    Ripka, Pavel; Draxler, Karel; Styblíková, Renata

    2016-01-01

    Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component. PMID:26805830

  11. Lessons learned, DC-XA

    SciTech Connect

    Steinmeyer, D.

    1997-01-01

    The Delta Clipper-Experimental A (DC-XA) program was conceived and specifically developed to provide a low cost reusable flight vehicle testbed for demonstrating performance and operability testing of advanced technologies required for the development of next generation Reusable Launch Vehicles (RLVs). The three primary program objectives addressed were: To integrate a variety of advanced launch vehicle technology components into the DC-XA flight vehicle testbed. Demonstrate performance, operability, and supportability of Advanced Launch Technologies (ALT) components through ground and flight testing of the DC-XA. Demonstrate rapid prototyping of hardware and software in a combined government, industry cooperative effort. {copyright} {ital 1997 American Institute of Physics.}

  12. Foam, Foam-resin composite and method of making a foam-resin composite

    NASA Technical Reports Server (NTRS)

    Cranston, John A. (Inventor); MacArthur, Doug E. (Inventor)

    1995-01-01

    This invention relates to a foam, a foam-resin composite and a method of making foam-resin composites. The foam set forth in this invention comprises a urethane modified polyisocyanurate derived from an aromatic amino polyol and a polyether polyol. In addition to the polyisocyanurate foam, the composite of this invention further contains a resin layer, wherein the resin may be epoxy, bismaleimide, or phenolic resin. Such resins generally require cure or post-cure temperatures of at least 350.degree. F.

  13. Compact dc link

    SciTech Connect

    Flairty, C. )

    1991-10-01

    The EPRI Compact Substation Project (a HVDC Converter Station) was developed, designed, and constructed per EPRI Agreement RP213. In December 1983, the converter station operated at its rating (100 MW power transmission and 300 kV dc bias plus 100 kV operating voltage). From January to May 1984, the converter station operated at various power transmission levels. Operation was intermittent due to a randomly occurring voltage breakdown. The voltage breakdown was isolated to the steel tanks containing the thyristor valves in an SF{sub 6} environment. The type of insulators stressed within the valve tanks were: (1) the epoxy cone shape insulators providing an interface to the bus entering the valve tank; (2) epoxy fiberglass hydraulic columns for the flow of the R113 refrigerant to and from the thyristor valves; and (3) the epoxy fiberglass support columns supporting the thyristor valves from the floor of the valve tank. The cause of the randomly occurring breakdown was investigated and determined to be the epoxy fiberglass support columns. The random dielectric breakdowns were due to excessive voltage gradients existing at the epoxy fiberglass support columns. This probably was caused by the misplacement of an internal insert within the column with respect to an external shield on the column. The cost and time to retrofit the support columns outweighed the benefits expected from resuming the project. Consequently, work was terminated and the equipment disassembled. Examination of the epoxy fiberglass support columns revealed several arcing tracks along the inside surface confirming the earlier hypothesis. 53 figs., 32 tabs.

  14. Digital Control Technologies for Modular DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Button, Robert M.; Kascak, Peter E.; Lebron-Velilla, Ramon

    2002-01-01

    Recent trends in aerospace Power Management and Distribution (PMAD) systems focus on using commercial off-the-shelf (COTS) components as standard building blocks. This move to more modular designs has been driven by a desire to reduce costs and development times, but is also due to the impressive power density and efficiency numbers achieved by today's commercial DC-DC converters. However, the PMAD designer quickly learns of the hidden "costs" of using COTS converters. The most significant cost is the required addition of external input filters to meet strict electromagnetic interference (MIAMI) requirements for space systems. In fact, the high power density numbers achieved by the commercial manufacturers are greatly due to the lack of necessary input filters included in the COTS module. The NASA Glenn Research Center is currently pursuing a digital control technology that addresses this problem with modular DC-DC converters. This paper presents the digital control technologies that have been developed to greatly reduce the input filter requirements for paralleled, modular DC-DC converters. Initial test result show that the input filter's inductor size was reduced by 75 percent, and the capacitor size was reduced by 94 percent while maintaining the same power quality specifications.

  15. High Temperature Transfer Molding Resins

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor); Hergenrother, Paul M. (Inventor)

    2000-01-01

    High temperature resins containing phenylethynyl groups that are processable by transfer molding have been prepared. These phenylethynyl containing oligomers were prepared from aromatic diamines containing phenylethynyl groups and various ratios of phthalic anhydride and 4-phenylethynlphthalic anhydride in glacial acetic acid to form a mixture of imide compounds in one step. This synthetic approach is advantageous since the products are a mixture of compounds and consequently exhibit a relatively low melting temperature. In addition, these materials exhibit low melt viscosities which are stable for several hours at 210-275 C, and since the thermal reaction of the phenylethynyl group does not occur to any appreciable extent at temperatures below 300 C, these materials have a broad processing window. Upon thermal cure at approximately 300-350 C, the phenylethynyl groups react to provide a crosslinked resin system. These new materials exhibit excellent properties and are potentially useful as adhesives, coatings, films, moldings and composite matrices.

  16. Advanced thermoplastic resins, phase 2

    NASA Technical Reports Server (NTRS)

    Brown, A. M.; Hill, S. G.; Falcone, A.

    1991-01-01

    High temperature structural resins are required for use on advanced aerospace vehicles as adhesives and composite matrices. NASA-Langley developed polyimide resins were evaluated as high temperature structural adhesives for metal to metal bonding and as composite matrices. Adhesive tapes were prepared on glass scrim fabric from solutions of polyamide acids of the semicrystalline polyimide LARC-CPI, developed at the NASA-Langley Research Center. Using 6Al-4V titanium adherends, high lap shear bond strengths were obtained at ambient temperature (45.2 MPa, 6550 psi) and acceptable strengths were obtained at elevated temperature (14.0 MPa, 2030 psi) using the Pasa-Jell 107 conversion coating on the titanium and a bonding pressure of 1.38 MPa (200 psi). Average zero degree composite tensile and compressive strengths of 1290 MPa (187 ksi) and 883 MPa (128 ksi) respectively were obtained at ambient temperature with unsized AS-4 carbon fiber reinforcement.

  17. Pharmaceutical Applications of Ion-Exchange Resins

    NASA Astrophysics Data System (ADS)

    Elder, David P.

    2005-04-01

    The historical uses of ion-exchange resins and a summary of the basic chemical principles involved in the ion-exchange process are discussed. Specific applications of ion-exchange resins are provided. The utility of these agents to stabilize drugs are evaluated. Commonly occurring chemical and physical incompatibilities are reviewed. Ion-exchange resins have found applicability as inactive pharmaceutical constituents, particularly as disintegrants (inactive tablet ingredient whose function is to rapidly disrupt the tablet matrix on contact with gastric fluid). One of the more elegant approaches to improving palatability of ionizable drugs is the use of ion-exchange resins as taste-masking agents. The selection, optimization of drug:resin ratio and particle size, together with a review of scaleup of typical manufacturing processes for taste-masked products are provided. Ion-exchange resins have been extensively utilized in oral sustained-release products. The selection, optimization of drug:resin ratio and particle size, together with a summary of commonly occurring commercial sustained-release products are discussed. Ion-exchange resins have also been used in topical products for local application to the skin, including those where drug flux is controlled by a differential electrical current (ionotophoretic delivery). General applicability of ion-exchange resins, including ophthalmic delivery, nasal delivery, use as drugs in their own right (e.g., colestyramine, formerly referred to as cholestyramine), as well as measuring gastrointestinal transit times, are discussed. Finally, pharmaceutical monographs for ion-exchange resins are reviewed.

  18. Phosphorus-containing imide resins

    NASA Technical Reports Server (NTRS)

    Varma, I. K.; Fohlen, G. M.; Parker, J. A. (Inventor)

    1984-01-01

    Flame-resistant reinforced bodies are disclosed which are composed of reinforcing fibers, filaments or fabrics in a cured body of bis- and tris-imide resins derived from tris(m-aminophenyl) phosphine oxides by reaction with maleic anhydride or its derivatives, or of addition polymers of such imides, including a variant in which a mono-imide is condensed with a dianhydride and the product is treated with a further quantity of maleic anhydride.

  19. High-Temperature Polyimide Resin

    NASA Technical Reports Server (NTRS)

    Vanucci, Raymond D.; Malarik, Diane C.

    1990-01-01

    Improved polyimide resin used at continuous temperatures up to 700 degrees F (371 degrees C). PMR-II-50, serves as matrix for fiber-reinforced composites. Material combines thermo-oxidative stability with autoclave processability. Used in such turbine engine components as air-bypass ducts, vanes, bearings, and nozzle flaps. Other potential applications include wing and fuselage skins on high-mach-number aircraft and automotive engine blocks and pistons.

  20. Synthesis of improved polyester resins

    NASA Technical Reports Server (NTRS)

    Mcleod, A. H.; Delano, C. B.

    1979-01-01

    Eighteen aromatic unsaturated polyester prepolymers prepared by a modified interfacial condensation technique were investigated for their solubility in vinyl monomers and ability to provide high char yield forming unsaturated polyester resins. The best resin system contained a polyester prepolymer of phthalic, fumaric and diphenic acids reacted with 2,7-naphthalene diol and 9,9-bis(4-hydroxyphenyl)fluorene. This prepolymer is very soluble in styrene, divinyl benzene, triallyl cyanurate, diallyl isophthalate and methylvinylpyridine. It provided anaerobic char yields as high as 41 percent at 800 C. The combination of good solubility and char yield represents a significant improvement over state-of-the-art unsaturated polyester resins. The majority of the other prepolymers had only low or no solubility in vinyl monomers. Graphite composites from this prepolymer with styrene were investigated. The cause for the observed low shear strengths of the composites was not determined, however 12-week aging of the composites at 82 C showed that essentially no changes in the composites had occurred.

  1. ELUTION OF URANIUM FROM RESIN

    DOEpatents

    McLEan, D.C.

    1959-03-10

    A method is described for eluting uranium from anion exchange resins so as to decrease vanadium and iron contamination and permit recycle of the major portion of the eluats after recovery of the uranium. Diminution of vanadium and iron contamination of the major portion of the uranium is accomplished by treating the anion exchange resin, which is saturated with uranium complex by adsorption from a sulfuric acid leach liquor from an ore bearing uranium, vanadium and iron, with one column volume of eluant prepared by passing chlorine into ammonium hydroxide until the chloride content is about 1 N and the pH is about 1. The resin is then eluted with 8 to 9 column volumes of 0.9 N ammonium chloride--0.1 N hydrochloric acid solution. The eluants are collected separately and treated with ammonia to precipitate ammonium diuranate which is filtered therefrom. The uranium salt from the first eluant is contaminated with the major portion of ths vanadium and iron and is reworked, while the uranium recovered from the second eluant is relatively free of the undesirable vanadium and irons. The filtrate from the first eluant portion is discarded. The filtrate from the second eluant portion may be recycled after adding hydrochloric acid to increase the chloride ion concentration and adjust the pH to about 1.

  2. Assessment of flow and cure monitoring using direct current and alternating current sensing in vacuum-assisted resin transfer molding

    NASA Astrophysics Data System (ADS)

    Vaidya, Uday K.; Jadhav, Nitesh C.; Hosur, Mahesh V.; Gillespie, John W., Jr.; Fink, Bruce K.

    2000-12-01

    Vacuum-assisted resin transfer molding (VARTM) is an emerging manufacturing technique that holds promise as an affordable alternative to traditional autoclave molding and automated fiber placement for producing large-scale structural parts. In VARTM, the fibrous preform is laid on a single-sided tool, which is then bagged along with the infusion and vacuum lines. The resin is then infused through the preform, which causes simultaneous wetting in its in-plane and transverse directions. An effective sensing technique is essential so that comprehensive information pertaining to the wetting of the preform, arrival of resin at various locations, cure gradients associated with thickness and presence of dry spots may be monitored. In the current work, direct current (dc) and alternating current sensing/monitoring techniques were adopted for developing a systematic understanding of the resin position and cure on plain weave S2-glass preforms with Dow Derakane vinyl ester VE 411-350, Shell EPON RSL 2704/2705 and Si-AN epoxy as the matrix systems. A SMARTweave dc sensing system was utilized to conduct parametric studies: (a) to compare the flow and cure of resin through the stitched and non-stitched preforms; (b) to investigate the influence of sensor positioning, i.e. top, middle and bottom layers; and (c) to investigate the influence of positioning of the process accessories, i.e. resin infusion point and vacuum point on the composite panel. The SMARTweave system was found to be sensitive to all the parametric variations introduced in the study. Furthermore, the results obtained from the SMARTweave system were compared to the cure monitoring studies conducted by using embedded interdigitated (IDEX) dielectric sensors. The results indicate that SMARTweave sensing was a viable alternative to obtaining resin position and cure, and was more superior in terms of obtaining global information, in contrast to the localized dielectric sensing approach.

  3. 21 CFR 177.2510 - Polyvinylidene fluoride resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyvinylidene fluoride resins. 177.2510 Section... Repeated Use § 177.2510 Polyvinylidene fluoride resins. Polyvinylidene fluoride resins may be safely used... fluoride resins consist of basic resins produced by the polymerization of vinylidene fluoride. (b)...

  4. Scintillating 99Tc Selective Ion Exchange Resins

    SciTech Connect

    Mitchell Greenhalgh; Richard D. Tillotson

    2012-07-01

    Scintillating technetium (99Tc) selective ion exchange resins have been developed and evaluated for equilibrium capacities and detection efficiencies. These resins can be utilized for the in-situ concentration and detection of low levels of pertechnetate anions (99TcO4-) in natural waters. Three different polystyrene type resin support materials were impregnated with varying amounts of tricaprylmethylammonium chloride (Aliquat 336) extractant, several different scintillating fluors and wavelength shifters. The prepared resins were contacted batch-wise to equilibrium over a wide range of 99TcO4- concentrations in natural water. The measured capacities were used to develop Langmuir adsorption isotherms for each resin. 99Tc detection efficiencies were determined and up to 71.4 ± 2.6% was achieved with some resins. The results demonstrate that a low level detection limit for 99TcO4- in natural waters can be realized.

  5. Development of tough, moisture resistant laminating resins

    NASA Technical Reports Server (NTRS)

    Brand, R. A.; Harrison, E. S.

    1982-01-01

    Tough, moisture resistant laminating resins for employment with graphite fibers were developed. The new laminating resins exhibited cost, handleability and processing characteristics equivalent to 394K (250 F) curing epoxies. The laminating resins were based on bisphenol A dicyanate and monofunctional cyanates with hydrophobic substituents. These resins sorb only small quantities of moisture at equilibrium (0.5% or less) with minimal glass transition temperature depression and represent an improvement over epoxies which sorb around 2% moisture at equilibrium. Toughening was accomplished by the precipitation of small diameter particles of butadiene nitrile rubber throughout the resin matrix. The rubber domains act as microcrack termini and energy dissipation sites, allowing increased stress accommodation prior to catastrophic failure. A unique blend of amine terminated butadiene nitrile elastomer (MW 2,000) and a high nitrile content butadiene nitrile rubber yielded the desired resin morphology.

  6. New modified hydrocarbon resins; An alternative to styrenated terpene resins in hot melts

    SciTech Connect

    Carper, J.D. )

    1990-06-01

    This paper reports on the development of two hydrocarbon-based resin formulations that could be used with different thermoplastic block copolymers to formulate pressure-sensitive adhesives. Results are examined with one of these resins in formulations with styrene-isoprene-styrene (SIS) and styrene-butadiene (SB) compounds. The new modified hydrocarbon resin, with a softening point of 98{degrees} C, matches the adhesive performance of a terpene resin with a softening point of 105{degrees} C. The resin performs as well as the modified terpene in SIS-, SB-, and EVA-based adhesives. The new hydrocarbon resin is especially well suited for hot-melt adhesives. It exhibits low volatility, good color stability, and excellent melt viscosity stability. Since the new resin is based on petroleum hydrocarbon feedstocks, it should be available at moderate, stable prices. The other hydrocarbon resin, with a softening point of 85{degrees} C, produced comparable results.

  7. Porous Ceramic Spheres from Ion Exchange Resin

    NASA Technical Reports Server (NTRS)

    Dynys, Fred

    2005-01-01

    A commercial cation ion exchange resin, cross-linked polystyrene, has been successfully used as a template to fabricate 20 to 50 micron porous ceramic spheres. Ion exchange resins have dual template capabilities. Pore architecture of the ceramic spheres can be altered by changing the template pattern. Templating can be achieved by utilizing the internal porous structure or the external surface of the resin beads. Synthesis methods and chemical/physical characteristics of the ceramic spheres will be reported.

  8. Resin selection criteria for tough composite structures

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Smith, G. T.

    1983-01-01

    Resin selection criteria are derived using a structured methodology consisting of an upward integrated mechanistic theory and its inverse (top-down structured theory). These criteria are expressed in a "criteria selection space" which are used to identify resin bulk properties for improved composite "toughness". The resin selection criteria correlate with a variety of experimental data including laminate strength, elevated temperature effects and impact resistance.

  9. Novel silica-based ion exchange resin

    SciTech Connect

    1997-11-01

    Eichrom`s highly successful Diphonixo resin resembles a conventional ion exchange resin in its use of sulfonic acid ligands on a styrene- divinylbenzene matrix. Diphonix resin exhibits rapid exchange kinetics that allow economical operation of ion exchange systems. Unlike conventional resins, Diphonix resin contains chelating ligands that are diphosphonic acid groups that recognize and remove the targeted metals and reject the more common elements such as sodium, calcium and magnesium. This latter property makes Diphonix ideal for many industrial scale applications, including those involving waste treatment. For treatment of low-level, transuranic (TRU) and high- level radioactive wastes, Diphonix`s polystyrene backbone hinders its application due to radiolytic stability of the carbon-hydrogen bonds and lack of compatibility with expected vitrification schemes. Polystyrene-based Diphonix is approximately 60% carbon- hydrogen. In response to an identified need within the Department of Energy for a resin with the positive attributes of Diphonix that also exhibits greater radiolytic stability and final waste form compatibility, Eichrom has successfully developed a new, silica-based resin version of Diphonix. Target application for this new resin is for use in environmental restoration and waste management situations involving the processing of low-level, transuranic and high-level radioactive wastes. The resin can also be used for processing liquid mixed waste (waste that contains low level radioactivity and hazardous constituents) including mixed wastes contaminated with organic compounds. Silica-based Diphonix is only 10% carbon-hydrogen, with the bulk of the matrix silica.

  10. Characterization of PMR polyimide resin and prepreg

    NASA Technical Reports Server (NTRS)

    Lindenmeyer, P. H.; Sheppard, C. H.

    1984-01-01

    Procedures for the chemical characterization of PMR-15 resin solutions and graphite-reinforced prepregs were developed, and a chemical data base was established. In addition, a basic understanding of PMR-15 resin chemistry was gained; this was translated into effective processing procedures for the production of high quality graphite composites. During the program the PMR monomers and selected model compounds representative of postulated PMR-15 solution chemistry were acquired and characterized. Based on these data, a baseline PMR-15 resin was formulated and evaluated for processing characteristics and composite properties. Commercially available PMR-15 resins were then obtained and chemically characterized. Composite panels were fabricated and evaluated.

  11. 21 CFR 177.1550 - Perfluorocarbon resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... for repeated use in contact with food. (d) Specifications—(1) Infrared identification. Perfluorocarbon resins can be identified by their characteristic infrared spectra. (2) Melt-viscosity. (i) The...

  12. Bending rigidity of composite resin coating clasps.

    PubMed

    Ikebe, K; Kibi, M; Ono, T; Nokubi, T

    1993-12-01

    The purpose of this study is to examine the bending profiles of composite resin coating cast clasps. The cobalt-chromium alloy cast clasps were made using tapered wax pattern. Silane coupling method (Silicoater MD, Kulzer Co.) was used to attach composite resin to metal surface. The breakage and the bending rigidity of composite resin coating clasps were evaluated. Results were as follows: 1) After the repeated bending test to the tips of clasp arm at 10,000 times in 0.25 mm deflection, neither crack on composite resin surface nor separation at resin/metal interface was observed in any specimen. 2) There was no significant difference in the bending rigidity of clasp arms between before and after composite resin coating. From these results, it was demonstrated that the composite resin coating cast clasp was available in clinical cases and coating with composite resin had little influence on the bending rigidity of clasp arms. Therefore, it was suggested that our clasp designing and fabricating system to control the bending rigidity of clasp arms could be applied to composite resin coating clasps. PMID:8935086

  13. Sand control with resin and explosive

    SciTech Connect

    Dees, J.M.; Begnaud, W.J.; Sahr, N.L.

    1992-09-08

    This patent describes a method for treating a well having perforated casing to prevent solids movement through the perforations and into the wellbore. It comprises positioning a quantity of liquid resin solution such that the solution occupies the interval of the casing having perforations; positioning an explosive in proximity with the liquid resin solution; detonating the explosive; displacing the liquid resin solution remaining in the wellbore after step (c) through the perforations with a displacing fluid; and injecting a chemical solution through the perforations to cause the resin to polymerize to form a consolidated permeable matrix.

  14. 75 FR 36298 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-8-31, DC-8-32, DC-8-33, DC-8-41...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-25

    ...-09-04, Amendment 39-15484 (73 FR 21523, April 22, 2008), for all Model DC-8-31, DC-8-32, DC-8-33, DC... ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and 3... removing Amendment 39-15484 (73 FR 21523, April 22, 2008) and adding the following new AD:...

  15. Imide modified epoxy matrix resins

    NASA Technical Reports Server (NTRS)

    Scola, D. A.

    1982-01-01

    Results of a program designed to develop tough imide modified epoxy (IME) resins cured by bisimide amine (BIA) hardeners are presented. State of the art epoxy resin, MY720, was used. Three aromatic bisimide amines and one aromatic aliphatic BIA were evaluated. BIA's derived from 6F anhydride (3,3 prime 4,4 prime-(hexafluoro isopropyl idene) bis (phthalic anhydride) and diamines, 3,3 prime-diam nodiphenyl sulfone (3,3 prime-DDS), 4,4 prime-diamino diphenyl sulfone (4,4 prime-DDS), 1.12-dodecane diamine (1,12-DDA) were used. BIA's were abbreviated 6F-3,3 prime-DDS, 6F-4,4 prime-DDS, 6F-3,3 prime-DDS-4,4 prime DDS, and 6F-3,3 prime-DDS-1,12-DDA corresponding to 6F anhydride and diamines mentioned. Epoxy resin and BIA's (MY720/6F-3,3 prime-DDS, MY720/6F-3,3 prime-DDS-4,4 prime-DDS, MY720/6F-3,3 prime-DDS-1,12-DDA and a 50:50 mixture of a BIA and parent diamine, MY720/6F-3,3 prime-DDS/3,3 prime-DDS, MY720/6F-3,3 prime-DDS-4,4 prime-DDS/3,3 prime-DDS, MY720/6F-3,3 prime-DDS-1,12-DDA/3,3 prime-DDS were studied to determine effect of structure and composition. Effect of the addition of two commercial epoxies, glyamine 200 and glyamine 100 on the properties of several formulations was evaluated. Bisimide amine cured epoxies were designated IME's (imide modified epoxy). Physical, thermal and mechanical properties of these resins were determined. Moisture absorption in boiling water exhibited by several of the IME's was considerably lower than the state of the art epoxies (from 3.2% for the control and state of the art to 2.0 wt% moisture absorption). Char yields are increased from 20% for control and state of the art epoxies to 40% for IME resins. Relative toughness characteristics of IME resins were measured by 10 deg off axis tensile tests of Celion 6000/IME composites. Results show that IME's containing 6F-3,3 prime-DDS or 6F-3,3 prime-DDS-1,12-DDA improved the "toughness" characteristics of composites by about 35% (tensile strength), about 35% (intralaminar shear

  16. Commercial Of-The Shelf DC/DC Converter

    NASA Astrophysics Data System (ADS)

    Denzinger, W.; Baumel, S.

    2011-10-01

    A commercial of-the-shelf (COTS) DC/DC converter for the supply of digital electronics on board of spacecraft has been developed with special emphasis on: *Low cost Readily available *Easy manufacturing *No use of ITAR listed EEE parts like rad-hard mosfets *Minimum number of rad-hard digital and analog IC's *Design tolerance against SEE by appropriate filtering The study was supported by the European Space Agency (ESA) under the contract number 21729/08/NL7LvH.

  17. Low dose failures of hardened DC-DC power converters

    NASA Technical Reports Server (NTRS)

    Lehman, J.; Yui, C.; Rax, B. G.; Miyahira, T. F.; Weideman, M.; Schrick, P.; Swift, G. M.; Johnston, A. H.

    2002-01-01

    Box-level total dose testing of the FOG (Fiber Optic Gyro) by IXSEA at ESA's GammabeamFacility were abruptly terminated at 8krad (Si) due to catastrophic failure (complete shutdown). This was unexpected because all components within the gyro were supposedly radiation tolerant. Further testing showed that the components responsible for the failure were two DC-DC converters, manufactured by Interpoint, that stopped regulating shortly before shutdown. This paper summarizes diagnostic test results for the converters to determine the underlying cause of the unexpected failure at low levels of radiation.

  18. Light-weight DC to very high voltage DC converter

    DOEpatents

    Druce, R.L.; Kirbie, H.C.; Newton, M.A.

    1998-06-30

    A DC-DC converter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current. 1 fig.

  19. Light-weight DC to very high voltage DC converter

    DOEpatents

    Druce, Robert L.; Kirbie, Hugh C.; Newton, Mark A.

    1998-01-01

    A DC-DC converter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current.

  20. High refractive index photocurable resins

    NASA Astrophysics Data System (ADS)

    Morford, Robert V.; Mercado, Ramil L.; Planje, Curtis E.; Flaim, Tony D.

    2005-04-01

    The performance of optoelectronic devices can be increased by incorporating a high refractive index layer into the system. This paper describes several potential high refractive index resin candidates. Our materials include the added advantages over other systems because the new materials are cationically photocurable and free flowing, have low shrinkage upon cure, have no (or little) volatile organic components, are applicable by a variety of methods (dip coating, roller coating, injection molding, or film casting), can be applied in a variety of thicknesses (10-100 m), are fast-curing, and possess robust physical properties. Particular attention focuses on the refractive index in the visible spectrum, light transmission, and formulation viscosity.

  1. Polyimide Resins Resist Extreme Temperatures

    NASA Technical Reports Server (NTRS)

    2009-01-01

    Spacecraft and aerospace engines share a common threat: high temperature. The temperatures experienced during atmospheric reentry can reach over 2,000 F, and the temperatures in rocket engines can reach well over 5,000 F. To combat the high temperatures in aerospace applications, Dr. Ruth Pater of Langley Research Center developed RP-46, a polyimide resin capable of withstanding the most brutal temperatures. The composite material can push the service temperature to the limits of organic materials. Designed as an environmentally friendly alternative to other high-temperature resins, the RP-46 polyimide resin system was awarded a 1992 "R&D 100" award, named a "2001 NASA Technology of the Year," and later, due to its success as a spinoff technology, "2004 NASA Commercial Invention of the Year." The technology s commercial success also led to its winning the Langley s "Paul F. Holloway Technology Transfer Award" as well as "Richard T. Whitcom Aerospace Technology Transfer Award" both for 2004. RP-46 is relatively inexpensive and it can be readily processed for use as an adhesive, composite, resin molding, coating, foam, or film. Its composite materials can be used in temperatures ranging from minus 150 F to 2,300 F. No other organic materials are known to be capable of such wide range and extreme high-temperature applications. In addition to answering the call for environmentally conscious high-temperature materials, RP-46 provides a slew of additional advantages: It is extremely lightweight (less than half the weight of aluminum), chemical and moisture resistant, strong, and flexible. Pater also developed a similar technology, RP-50, using many of the same methods she used with RP-46, and very similar in composition to RP-46 in terms of its thermal capacity and chemical construction, but it has different applications, as this material is a coating as opposed to a buildable composite. A NASA license for use of this material outside of the Space Agency as well as

  2. Phosphorus-containing imide resins

    NASA Technical Reports Server (NTRS)

    Varma, I. K.; Fohlen, G. M.; Parker, J. A. (Inventor)

    1985-01-01

    Cured polymers of bis and tris-imides derived from tris(m-aminophenyl) phosphine oxides by reaction with maleic anhydride or its derivatives, and addition polymers of such imides, including a variant in which a monoimide is condensed with a dianhydride and the product is treated with a further quantity of maleic anhydride prior to curing are disclosed and claimed. Such polymers are flame resistant. Also disclosed are an improved method of producing tris(m-aminophenyl) phosphine oxides from the nitro analogues by reduction with hydrazine hydrate using palladized charcoal or Raney nickel as the catalyst and fiber reinforced cured resin composites.

  3. Evaluation of Polymerization Efficacy in Composite Resins via FT-IR Spectroscopy and Vickers Microhardness Test

    PubMed Central

    Jafarzadeh, Tahereh-Sadat; Erfan, Mohammad; Behroozibakhsh, Marjan; Fatemi, Mostafa; Masaeli, Reza; Rezaei, Yashar; Bagheri, Hossein; Erfan, Yasaman

    2015-01-01

    Background and aims. Polymerization efficacy affects the properties and performance of composite resin restorations.The purpose of this study was to evaluate the effectiveness of polymerization of two micro-hybrid, two nano-hybrid and one nano-filled ormocer-based composite resins, cured by two different light-curing systems, using Fourier transformation infrared (FT-IR) spectroscopy and Vickers microhardness testing at two different depths (top surface, 2 mm). Materials and methods. For FT-IR spectrometry, five cylindrical specimens (5mm in diameter × 2 mm in length) were prepared from each composite resin using Teflon molds and polymerized for 20 seconds. Then, 70-μm wafers were sectioned at the top surface and at2mm from the top surface. The degree of conversion for each sample was calculated using FT-IR spectroscopy. For Vickers micro-hardness testing, three cylindrical specimens were prepared from each composite resin and polymerized for 20 seconds. The Vickers microhardness test (Shimadzu, Type M, Japan) was performed at the top and bottom (depth=2 mm) surfaces of each specimen. Three-way ANOVA with independent variables and Tukey tests were performed at 95% significance level. Results. No significant differences were detected in degree of conversion and microhardness between LED and QTH light-curing units except for the ormocer-based specimen, CeramX, which exhibited significantly higher DC by LED. All the composite resins showed a significantly higher degree of conversion at the surface. Microhardness was not significantly affected by depth, except for Herculite XRV Ultra and CeramX, which showed higher values at the surface. Conclusion. Composite resins containing nano-particles generally exhibited more variations in degree of conversion and microhardness. PMID:26889359

  4. Evaluation of Polymerization Efficacy in Composite Resins via FT-IR Spectroscopy and Vickers Microhardness Test.

    PubMed

    Jafarzadeh, Tahereh-Sadat; Erfan, Mohammad; Behroozibakhsh, Marjan; Fatemi, Mostafa; Masaeli, Reza; Rezaei, Yashar; Bagheri, Hossein; Erfan, Yasaman

    2015-01-01

    Background and aims. Polymerization efficacy affects the properties and performance of composite resin restorations.The purpose of this study was to evaluate the effectiveness of polymerization of two micro-hybrid, two nano-hybrid and one nano-filled ormocer-based composite resins, cured by two different light-curing systems, using Fourier transformation infrared (FT-IR) spectroscopy and Vickers microhardness testing at two different depths (top surface, 2 mm). Materials and methods. For FT-IR spectrometry, five cylindrical specimens (5mm in diameter × 2 mm in length) were prepared from each composite resin using Teflon molds and polymerized for 20 seconds. Then, 70-μm wafers were sectioned at the top surface and at2mm from the top surface. The degree of conversion for each sample was calculated using FT-IR spectroscopy. For Vickers micro-hardness testing, three cylindrical specimens were prepared from each composite resin and polymerized for 20 seconds. The Vickers microhardness test (Shimadzu, Type M, Japan) was performed at the top and bottom (depth=2 mm) surfaces of each specimen. Three-way ANOVA with independent variables and Tukey tests were performed at 95% significance level. Results. No significant differences were detected in degree of conversion and microhardness between LED and QTH light-curing units except for the ormocer-based specimen, CeramX, which exhibited significantly higher DC by LED. All the composite resins showed a significantly higher degree of conversion at the surface. Microhardness was not significantly affected by depth, except for Herculite XRV Ultra and CeramX, which showed higher values at the surface. Conclusion. Composite resins containing nano-particles generally exhibited more variations in degree of conversion and microhardness. PMID:26889359

  5. 21 CFR 175.380 - Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... condensation of xylene-formaldehyde resin and 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins, to... include resins produced by the condensation of allyl ether of mono-, di-, or trimethylol phenol and...

  6. TMI-2 purification demineralizer resin study

    SciTech Connect

    Thompson, J D; Osterhoudt, T R

    1984-05-01

    Study of the Makeup and Purification System demineralizers at TMI-2 has established that fuel quantities in the vessels are low, precluding criticality, that the high radioactive cesium concentration on the demineralizer resins can be chemically removed, and that the demineralizer resins can probably be removed from the vessels by sluicing through existing plant piping. Radiation measurements from outside the demineralizers establishing that there is between 1.5 and 5.1 (probably 3.3) lb of fuel in the A vessel and less than that amount in the B vessel. Dose rates up to 2780 R per hour were measured on contact with the A demineralizer. Remote visual observation of the A demineralizer showed a crystalline crust overlaying amber-colored resins. The cesium activity in solid resin samples ranged from 220 to 16,900 ..mu..Ci/g. Based on this information, researchers concluded that the resins cannot be removed through the normal pathway in their present condition. Studies do show that the resins will withstand chemical processing designed to rinse and elute cesium from the resins. The process developed should work on the TMI-2 resins.

  7. Modified resins for solid-phase extraction

    DOEpatents

    Fritz, James S.; Sun, Jeffrey J.

    1993-07-27

    A process of treating aqueous solutions to remove organic solute contaminants by contacting an aqueous solution containing polar organic solute contaminants with a functionalized polystyrene-divinyl benzene adsorbent resin, with the functionalization of said resin being accomplished by organic hydrophilic groups such as hydroxymethyl, acetyl and cyanomethyl.

  8. Modified resins for solid-phase extraction

    DOEpatents

    Fritz, James S.; Sun, Jeffrey J.

    1991-12-10

    A process of treating aqueous solutions to remove organic solute contaminants by contacting an aqueous solution containing polar organic solute contaminants with a functionalized polystyrene-divinyl benzene adsorbent resin, with the functionalization of said resin being accomplished by organic hydrophilic groups such as hydroxymethyl, acetyl and cyanomethyl.

  9. Fluorinated diamond bonded in fluorocarbon resin

    DOEpatents

    Taylor, Gene W.

    1982-01-01

    By fluorinating diamond grit, the grit may be readily bonded into a fluorocarbon resin matrix. The matrix is formed by simple hot pressing techniques. Diamond grinding wheels may advantageously be manufactured using such a matrix. Teflon fluorocarbon resins are particularly well suited for using in forming the matrix.

  10. Silicone modified resins for graphite fiber laminates

    NASA Technical Reports Server (NTRS)

    Frost, L. W.; Bower, G. M.

    1980-01-01

    Six silicone modified resins were selected for evaluation in unidirectional filament wound graphite laminates. Neat samples of these resins had 1,000 C char residues of 6-63%. The highest flexural values measured for the laminates were a strength of 1,220 MPa and a modulus of 105 GPa. The highest interlaminar shear strength was 72 MPa.

  11. Some experiences with epoxy resin grouting compounds.

    PubMed

    Hosein, H R

    1980-07-01

    Epoxy resin systems are used in tiling and grouting in the construction industry. Because of the nature of the application, skin contact is the primary hazard. The most prevalent reaction was reddening of the forearms, followed by whole body reddening and loss of appetite, these latter two being associated with smoking while applying the resin. PMID:7415974

  12. 21 CFR 177.1555 - Polyarylate resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1555 Polyarylate resins. Polyarylate resins (CAS Reg. No. 51706-10-6) may be safely used as articles or components of articles intended for use...

  13. 21 CFR 177.1555 - Polyarylate resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1555 Polyarylate resins. Polyarylate resins (CAS Reg. No. 51706-10-6) may be safely used as articles or components of articles intended for use...

  14. 21 CFR 177.1555 - Polyarylate resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1555 Polyarylate resins. Polyarylate resins (CAS Reg. No. 51706-10-6) may be safely used as articles or components of articles intended for use...

  15. Optical and color stabilities of paint-on resins for shade modification of restorative resins.

    PubMed

    Arikawa, Hiroyuki; Kanie, Takahito; Fujii, Koichi; Ban, Seiji; Homma, Tetsuya; Takahashi, Hideo

    2004-06-01

    The purpose of this study was to examine the optical and color stabilities of the paint-on resin used for shade modification of restorative resins. Three shades of paint-on resin and two crown and bridge resins were used. The light transmittance characteristics of the materials during accelerated aging tests such as water immersion, toothbrush abrasion, ultraviolet (UV) light irradiation, and staining tests were measured. Discolorations of materials resulting from tests were also determined. There were no significant effects of water immersion, toothbrush abrasion and UV light irradiation on the light transmittance and visible color change of paint-on resins, whereas the staining tests significantly decreased the light transmittance and increased color change of the translucent shades of materials. Our results indicate that the paint-on resins exhibit stable optical properties and color appearance, which are at least as good as the crown and bridge resins. PMID:15287561

  16. Effect of Resin Viscosity in Fiber Reinforcement Compaction in Resin Injection Pultrusion Process

    NASA Astrophysics Data System (ADS)

    Shakya, N.; Roux, J. A.; Jeswani, A. L.

    2013-12-01

    In resin injection pultrusion, the liquid resin is injected through the injection slots into the fiber reinforcement; the liquid resin penetrates through the fibers as well as pushes the fibers towards the centerplane causing fiber compaction. The compacted fibers are more difficult to penetrate, thus higher resin injection pressure becomes necessary to achieve complete reinforcement wetout. Lower injection pressures below a certain range (depending upon the fiber volume fraction and resin viscosity) cannot effectively penetrate through the fiber bed and thus cannot achieve complete wetout. Also, if the degree of compaction is very high the fibers might become essentially impenetrable. The more viscous the resin is, the harder it is to penetrate through the fibers and vice versa. The effect of resin viscosity on complete wetout achievement with reference to fiber-reinforcement compaction is presented in this study.

  17. Piezometer completion report for borehole cluster sites DC-19, DC-20, and DC-22

    SciTech Connect

    Jackson, R.L.; Diediker, L.D.; Ledgerwood, R.K.; Veatch, M.D.

    1984-07-01

    This report describes the design and installation of multi-level piezometers at borehole cluster sites DC-19, DC-20 and DC-22. The network of borehole cluster sites will provide facilities for multi-level water-level monitoring across the RRL for piezometer baseline monitoring and for large-scale hydraulic stress testing. These groundwater-monitoring facilities were installed between August 1983 and March 1984. Three series of piezometer nests (A-, C- and D-series) were installed in nine hydrogeologic units (monitoring horizons) within the Columbia River Basalt Group at each borehole cluster site. In addition to the piezometer facilities, a B-series pumping well was installed at borehole cluster sites DC-20 and DC-22. The A-series piezometer nest monitors the basal Ringold sediments and the Rattlesnake Ridge interbed. The C-series piezometer nests monitors the six deepest horizons, which are in increasing depth, the Priest Rapids interflow, Sentinel Gap flow top, Ginkgo flow top, Rocky Coulee flow top, Cohassett flow top and Umtanum flow top. The D-series piezometer monitors the Mabton interbed. The B-series pumping well was completed in the Priest Rapids interflow. 21 refs., 6 figs., 6 tabs.

  18. Resin/graphite fiber composites

    NASA Technical Reports Server (NTRS)

    Cavano, P. J.

    1974-01-01

    Techniques were developed that provided thermo-oxidatively stable A-type polyimide/graphite fiber composites using the approach of in situ polymerization of monomeric reactants directly on reinforcing fibers, rather than employing separately prepared prepolymer varnish. This was accomplished by simply mixing methylene dianiline and two ester-acids and applying this solution to the fibers for subsequent molding. Five different formulated molecular weight resins were examined, and an optimized die molding procedure established for the 1500 formulated molecular weight system. Extensive ultrasonic inspection of composites was successfully utilized as a technique for monitoring laminate quality. Composite mechanical property studies were conducted with this polyimide resin at room temperature and after various time exposures in a thermo-oxidative environment at 561 K (550 F), 589 K (600 F) and 617 K (650 F). It was determined that such composites have a long term life in the temperature range of 561 K to 589 K. The final phase involved the fabrication and evaluation of a series of demonstration airfoil specimens.

  19. Physical Properties of Synthetic Resin Materials

    NASA Technical Reports Server (NTRS)

    Fishbein, Meyer

    1939-01-01

    A study was made to determine the physical properties of synthetic resins having paper, canvas, and linen reinforcements, and of laminated wood impregnated with a resin varnish. The results show that commercial resins have moduli of elasticity that are too low for structural considerations. Nevertheless, there do exist plastics that have favorable mechanical properties and, with further development, it should be possible to produce resin products that compare favorably with the light-metal alloys. The results obtained from tests on Compound 1840, resin-impregnated wood, show that this material can stand on its own merit by virtue of a compressive strength four times that of the natural wood. This increase in compressive strength was accomplished with an increase of density to a value slightly below three times the normal value and corrected one of the most serious defects of the natural product.

  20. Evaluation of resins for provisional restorations.

    PubMed

    Burgess, J O; Haveman, C W; Butzin, C

    1992-06-01

    An in vivo study of two resin materials (Barricaid and Caulk Temporary Crown and Bridge Resin) was done to determine the retention, post-operative sensitivity, and fabrication time of provisional restorations made from these materials. Following the placement of these resins in 67 intracoronal cavity preparations of 19 adult patients, a baseline evaluation was made which included a clinical examination and color slides. Twenty-four hours after the temporary restorations were placed, the patients completed evaluations of the post-operative sensitivity experienced. There was no difference in post-operative sensitivity between the teeth restored with Barricaid or Caulk Temporary Crown and Bridge Resin. At the insertion appointment of the final restoration, the interim restoration's success rate was determined. There was no difference between the retention of the two provisional materials. Fabrication time was significantly different with Barricaid restorations requiring less than one-half the fabrication time of the Caulk Temporary Crown and Bridge Resin material. PMID:1388950

  1. Release and toxicity of dental resin composite

    PubMed Central

    Gupta, Saurabh K.; Saxena, Payal; Pant, Vandana A.; Pant, Aditya B.

    2012-01-01

    Dental resin composite that are tooth-colored materials have been considered as possible substitutes to mercury-containing silver amalgam filling. Despite the fact that dental resin composites have improved their physico-chemical properties, the concern for its intrinsic toxicity remains high. Some components of restorative composite resins are released in the oral environment initially during polymerization reaction and later due to degradation of the material. In vitro and in vivo studies have clearly identified that these components of restorative composite resins are toxic. But there is a large gap between the results published by research laboratories and clinical reports. The objective of this manuscript was to review the literature on release phenomenon as well as in vitro and in vivo toxicity of dental resin composite. Interpretation made from the recent data was also outlined. PMID:23293458

  2. FT-Raman spectroscopy study of organic matrix degradation in nanofilled resin composite.

    PubMed

    Soares, Luís Eduardo Silva; Nahórny, Sídnei; Martin, Airton Abrahão

    2013-04-01

    This in vitro study evaluated the effect of light curing unit (LCU) type, mouthwashes, and soft drink on chemical degradation of a nanofilled resin composite. Samples (80) were divided into eight groups: halogen LCU, HS--saliva (control); HPT--Pepsi Twist®; HLC--Listerine®; HCP--Colgate Plax®; LED LCU, LS--saliva (control); LPT--Pepsi Twist®; LLC--Listerine®; LCP--Colgate Plax®. The degree of conversion analysis and the measure of the peak area at 2,930 cm-1 (organic matrix) of resin composite were done by Fourier-transform Raman spectroscopy (baseline, after 7 and 14 days). The data were subjected to multifactor analysis of variance (ANOVA) at a 95% confidence followed by Tukey's HSD post-hoc test. The DC ranged from 58.0% (Halogen) to 59.3% (LED) without significance. Differences in the peak area between LCUs were found after 7 days of storage in S and PT. A marked increase in the peak intensity of HLC and LLC groups was found. The soft-start light-activation may influence the chemical degradation of organic matrix in resin composite. Ethanol contained in Listerine® Cool Mint mouthwash had the most significant degradation effect. Raman spectroscopy is shown to be a useful tool to investigate resin composite degradation. PMID:23388411

  3. Effect of dual-peak LED unit on the polymerization of coinitiator-containing composite resins.

    PubMed

    Lee, Dong-Soo; Jeong, Tae-Sung; Kim, Shin; Kim, Hyung-Il; Kwon, Yong Hoon

    2012-01-01

    The purpose of the present study was to evaluate the effect of dual-peak LED on the polymerization of coinitiator-containing composite resins. For this, microhardness, degree of conversion (DC), and polymerization shrinkage were evaluated. Specimens (coinitiator-containing: Aelite LS Posterior, Tetric EvoCeram, and Vit-l-escence; only camphorquinone-containng: Filtek Z350 and Grandio) were light cured using a quartz-tungsten-halogen (QTH: OP), a single-peak light-emitting diode (LED) (L. E. Demetron: DM), and a dual-peak LED (G-light: GL), respectively. All specimens light cured using GL showed the highest microhardness both on the top and bottom surfaces compared with the values obtained using the rest light-curing units (LCUs). DC had no consistent trend correspond to the LCU, but rather product specific. OP yielded the lowest polymerization shrinkage on the specimens. The coinitiator-containing composite resins achieved the highest microhardness by the dual-peak LED (GL). However, the influence of GL on DC and polymerization shrinkage of the specimens was not consistent. PMID:22864221

  4. Solidification of ion exchange resin wastes

    SciTech Connect

    Not Available

    1982-08-01

    Solidification media investigated included portland type I, portland type III and high alumina cements, a proprietary gypsum-based polymer modified cement, and a vinyl ester-styrene thermosetting plastic. Samples formulated with hydraulic cement were analyzed to investigate the effects of resin type, resin loading, waste-to-cement ratio, and water-to-cement ratio. The solidification of cation resin wastes with portland cement was characterized by excessive swelling and cracking of waste forms, both after curing and during immersion testing. Mixed bed resin waste formulations were limited by their cation component. Additives to improve the mechanical properties of portland cement-ion exchange resin waste forms were evaluated. High alumina cement formulations dislayed a resistance to deterioration of mechanical integrity during immersion testing, thus providing a significant advantage over portland cements for the solidification of resin wastes. Properties of cement-ion exchange resin waste forms were examined. An experiment was conducted to study the leachability of /sup 137/Cs, /sup 85/Sr, and /sup 60/Co from resins modified in portland type III and high alumina cements. The cumulative /sup 137/Cs fraction release was at least an order of magnitude greater than that of either /sup 85/Sr or /sup 60/Co. Release rates of /sup 137/Cs in high alumina cement were greater than those in portland III cement by a factor of two.Compressive strength and leach testing were conducted for resin wastes solidified with polymer-modified gypsum based cement. /sup 137/Cs, /sup 85/Sr, and /sup 60/Co fraction releases were about one, two and three orders of magnitude higher, respectively, than in equivalent portland type III cement formulations. As much as 28.6 wt % dry ion exchange resin was successfully solidified using vinyl ester-styrene compared with a maximum of 25 wt % in both portland and gypsum-based cement.

  5. Physical and chemical properties of an antimicrobial Bis-GMA free dental resin with quaternary ammonium dimethacrylate monomer.

    PubMed

    Huang, Qi-ting; He, Jing-wei; Lin, Zheng-mei; Liu, Fang; Lassila, Lippo V J; Vallittu, Pekka K

    2016-03-01

    The objective of this study was to evaluate the antibacterial activity, physicochemical properties of the quaternary ammonium dimethacrylate monomer N,N-bis[2-(3-(methacryloyloxy)propanamido)-ethyl]-N-methylhexadecyl ammonium bromide (IMQ-16) containing diurethane dimethacrylate (UDMA)/tricyclodecane dimethanol diacrylate (SR833s) resin system and compare with bisphenylglycidyl dimethacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) resin system. It was hypothesized that the physical and chemical properties of the experimental polymers would be comparable with Bis-GMA/TEGDMA polymer and IMQ-16 monomer could endow the UDMA/SR833s resin with antibacterial activity. Double bond conversion (DC) was measured using Fourier transform infrared spectroscopy (FTIR). Mechanical properties including flexural strength (FS) and flexural modulus (FM) were measured by three-point bending test with bars of 2mm×2mm×25mm. Water sorption (WS) and solubility (WSL) were also investigated. Antibacterial activity of obtained polymers against Streptococcus mutans Ingbitt (S. mutans) was tested through direct contact test (DCT). The presence of antibacterial activity due to soluble components was also investigated by agar diffusion test (ADT). All of the polymers containing IMQ-16 exhibited improvements in WS and WSL, while maintaining equivalent DC and FS relative to the Bis-GMA/TEGDMA control system. Incorporation of 17% and 20% of IMQ-16 into UDMA/SR833s resin reduced the viable counts of S. mutans after incubation on the surface of the materials and produced no inhibition zones around the cured discs in ADT. UDMA/SR833s resin system is promising to formulate an antibacterial polymer with equivalent or even higher physicochemical properties relative to Bis-GMA/TEGDMA formulation. IMQ-16 is capable to endow UDMA/SR833s resin system with significant antibacterial activity when the mass ratio is 17% or 20%. PMID:26688422

  6. DC coupled Doppler radar physiological monitor.

    PubMed

    Zhao, Xi; Song, Chenyan; Lubecke, Victor; Boric-Lubecke, Olga

    2011-01-01

    One of the challenges in Doppler radar systems for physiological monitoring is a large DC offset in baseband outputs. Typically, AC coupling is used to eliminate this DC offset. Since the physiological signals of interest include frequency content near DC, it is not desirable to simply use AC coupling on the radar outputs. While AC coupling effectively removes DC offset, it also introduces a large time delay and distortion. This paper presents the first DC coupled IQ demodulator printed circuit board (PCB) design and measurements. The DC coupling is achieved by using a mixer with high LO to RF port isolation, resulting in a very low radar DC offset on the order of mV. The DC coupled signals from the PCB radar system were successfully detected with significant LNA gain without saturation. Compared to the AC coupled results, the DC coupled results show great advantages of less signal distortion and more accurate rate estimation. PMID:22254704

  7. Switching coordination of distributed dc-dc converters for highly efficient photovoltaic power plants

    DOEpatents

    Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja

    2014-09-09

    A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.

  8. Designing dc Inductors With Airgaps

    NASA Technical Reports Server (NTRS)

    Wagner, A. P.

    1986-01-01

    Optimal parameters obtained designing near saturation point. New iterative procedure aids design of dc inductors with airgaps in cores. For given core area and length, technique gives design having specified inductance and peak flux density in core, using minimum required copper weight. Executed rapidly on programmable, hand-held calculator. Applications include lightweight inductors for aircraft electronics.

  9. D.C. Fights Crime.

    ERIC Educational Resources Information Center

    American School and University, 1984

    1984-01-01

    Describes a 30-233 "Youth Awareness Program" in Washington, DC, to help students recognize the responsibilities of citizenship. Police collaborate with schools in providing classroom visits, field trips, and instructional materials aimed at specific areas of concern for adolescents, such as alcohol, drugs, smoking, sexuality, juvenile justice, and…

  10. Experiments with a DC Motor

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2010-01-01

    Experiments with an electric motor provide good opportunity to demonstrate some basic laws of electricity and magnetism. The aim of the experiments with a low-power dc motor is to show how the motor approaches its steady rotation and how its torque, mechanical power and efficiency depend on the rotation velocity. The tight relationship between the…

  11. DC-Powered Jumping Ring

    ERIC Educational Resources Information Center

    Jeffery, Rondo N.; Farhang, Amiri

    2016-01-01

    The classroom jumping ring demonstration is nearly always performed using alternating current (AC), in which the ring jumps or flies off the extended iron core when the switch is closed. The ring jumps higher when cooled with liquid nitrogen (LN2). We have performed experiments using DC to power the solenoid and find similarities and significant…

  12. Novel injectable and in situ curable glycolide/lactide based biodegradable polymer resins and composites.

    PubMed

    Xie, Dong; Park, Jong-Gu; Zhao, Jun; Turner, Charles H

    2007-07-01

    Novel in situ polymerizable liquid three-arm biodegradable oligomeric polyesters based upon glycolic acid (GA), L-lactic acid (LLA), and their copolymers are synthesized and characterized. Injectable and in situ curable polymer neat resins and their composites formulated with bioabsorbable beta-tricalcium phosphate are prepared at room temperature using photo- and redox-initiation systems, respectively. The cured neat resins show the initial compressive yield strength (YCS, MPa), modulus (M, MPa), ultimate compressive strength (UCS, MPa), and toughness (T, kN mm), ranging from 4.0 to 20.1, 201.5 to 730.2, 82.7 to 310.5, and 1.02 to 3.93. The cured composites show the initial YCS, M, UCS and T, ranging from 27.7 to 56.4, 1440 to 4870, 81.6 to 158.9, and 0.94 to 1.97. Increasing GA/LLA ratio increases all the initial compressive strengths of both neat resins and composites. Increasing filler content increases YCS and M but decreases UCS and T. A diametral tensile strength test shows the same trend as a compressive strength test. There seems to be an optimal flexural strength for the composite at the filler content around 43%. An increasing molar ratio increases curing time but decreases the degree of conversion (DC). An increasing filler content increases curing time but decreases exotherm and DC. During the course of degradation, all the materials show a burst degradation behavior within 24 h, followed by an increase in CS. The poly(glycolic acid) neat resin completely loses its strength at around Day 45. The composites completely lose their strengths at different time intervals, depending on their molar ratio and filler content. The degradation rate is found to be molar ratio and filler-content dependent. PMID:16920760

  13. Resin/graphite fiber composites

    NASA Technical Reports Server (NTRS)

    Cavano, P. J.

    1974-01-01

    Processing techniques were developed for the fabrication of both polyphenylquinoxaline and polyimide composites by the in situ polymerization of monomeric reactants directly on the graphite reinforcing fibers, rather than using previously prepared prepolymer varnishes. Void-free polyphenylquinoxaline composites were fabricated and evaluated for room and elevated flexure and shear properties. The technology of the polyimide system was advanced to the point where the material is ready for commercial exploitation. A reproducible processing cycle free of operator judgment factors was developed for fabrication of void-free composites exhibiting excellent mechanical properties and a long time isothermal life in the range of 288 C to 316 C. The effects of monomer reactant stoichiometry and process modification on resin flow were investigated. Demonstration of the utility and quality of this polyimide system was provided through the successful fabrication and evaluation of four complex high tip speed fan blades.

  14. Influence of the interposition of ceramic spacers on the degree of conversion and the hardness of resin cements.

    PubMed

    Calgaro, Patricia Angélica Milani; Furuse, Adilson Yoshio; Correr, Gisele Maria; Ornaghi, Bárbara Pick; Gonzaga, Carla Castiglia

    2013-01-01

    This study evaluated: I) the effect of photo-activation through ceramics on the degree of conversion (DC) and on the Knoop hardness (KHN) of light- and dual-cured resin cements; and II) two different protocols for obtaining the spectra of uncured materials, to determine the DC of a dual-cured resin cement. Thin films of cements were photo-activated through ceramics [feldspathic porcelain (FP); lithium disilicate glass-ceramics of low translucency (e.max-LT), medium opacity (e.max-MO) and high translucency (e.max-HT); glass-infiltrated alumina composite (IC) and polycrystalline zirconia (ZR)] with thicknesses of 1.5 and 2.0 mm. DC was analyzed by Fourier transform infrared (FTIR) spectroscopy. Two protocols were used to obtain the spectra of the uncured materials: I) base and catalyst pastes were mixed, and II) thin films of base and catalyst pastes were obtained separately, and an average was obtained. KHN assessment was performed with cylindrical specimens. The results were analyzed by ANOVA and Tukey's test (α= 0.05). The light-cured cement showed higher DC (61.9%) than the dual-cured cement (55.7%). The DC varied as follows: FP (65.4%), e.max-HT (65.1%), e.max-LT (61.8%), e.max-MO (60.9%), ZR (54.8%), and IC (44.9%). The light-cured cement showed lower KHN (22.0) than the dual-cured (25.6) cement. The cements cured under 1.5 mm spacers showed higher KHN (26.2) than when polymerized under 2.0 mm ceramics (21.3). Regarding the two protocols, there were significant differences only in three groups. Thus, both methods can be considered appropriate. The physical and mechanical properties of resin cements may be affected by the thickness and microstructure of the ceramic material interposed during photo-activation. PMID:24036978

  15. 49 CFR 173.165 - Polyester resin kits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Polyester resin kits. 173.165 Section 173.165... Polyester resin kits. (a) Polyester resin kits consisting of a base material component (Class 3, Packing..., according to the criteria for Class 3, applied to the base material. Additionally, polyester resin kits...

  16. 49 CFR 173.165 - Polyester resin kits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Polyester resin kits. 173.165 Section 173.165... Polyester resin kits. (a) Polyester resin kits consisting of a base material component (Class 3, Packing..., according to the criteria for Class 3, applied to the base material. Additionally, polyester resin kits...

  17. 49 CFR 173.165 - Polyester resin kits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Polyester resin kits. 173.165 Section 173.165... Polyester resin kits. (a) Except for transportation by aircraft, polyester resin kits consisting of a base.... Additionally, unless otherwise excepted in this subchapter, polyester resin kits must be packaged...

  18. 21 CFR 177.2355 - Mineral reinforced nylon resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Mineral reinforced nylon resins. 177.2355 Section... Repeated Use § 177.2355 Mineral reinforced nylon resins. Mineral reinforced nylon resins identified in... reinforced nylon resins consist of nylon 66, as identified in and complying with the specifications of §...

  19. 21 CFR 176.110 - Acrylamide-acrylic acid resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Acrylamide-acrylic acid resins. 176.110 Section... Paper and Paperboard § 176.110 Acrylamide-acrylic acid resins. Acrylamide-acrylic acid resins may be...) Acrylamide-acrylic acid resins are produced by the polymerization of acrylamide with partial hydrolysis or...

  20. DC to DC power converters and methods of controlling the same

    DOEpatents

    Steigerwald, Robert Louis; Elasser, Ahmed; Sabate, Juan Antonio; Todorovic, Maja Harfman; Agamy, Mohammed

    2012-12-11

    A power generation system configured to provide direct current (DC) power to a DC link is described. The system includes a first power generation unit configured to output DC power. The system also includes a first DC to DC converter comprising an input section and an output section. The output section of the first DC to DC converter is coupled in series with the first power generation unit. The first DC to DC converter is configured to process a first portion of the DC power output by the first power generation unit and to provide an unprocessed second portion of the DC power output of the first power generation unit to the output section.

  1. SEM and elemental analysis of composite resins

    SciTech Connect

    Hosoda, H.; Yamada, T.; Inokoshi, S. )

    1990-12-01

    Twenty-four chemically cured, 21 light-cured anterior, three light-cured anterior/posterior, and 18 light-cured posterior composite resins were examined using scanning electron microscopy, and the elemental composition of their filler particles was analyzed with an energy dispersive electron probe microanalyzer. According to the results obtained, the composite resins were divided into five groups (traditional, microfilled type, submicrofilled type, hybrid type, and semihybrid), with two additional hypothetical categories (microfilled and hybrid). Characteristics of each type were described with clinical indications for selective guidance of respective composite resins for clinical use.

  2. Class II Resin Composites: Restorative Options.

    PubMed

    Patel, Minesh; Mehta, Shamir B; Banerji, Subir

    2015-10-01

    Tooth-coloured, resin composite restorations are amongst the most frequently prescribed forms of dental restoration to manage defects in posterior teeth. The attainment of a desirable outcome when placing posterior resin composite restorations requires the clinician to have a good understanding of the benefits (as well as the limitations) posed by this material, together with a sound knowledge of placement technique. Numerous protocols and materials have evolved to assist the dental operator with this type of demanding posterior restoration. With the use of case examples, four techniques available are reported here. CPD/Clinical Relevance: This article explores varying techniques for the restoration of Class II cavities using resin composite. PMID:26685471

  3. Improved microbial-check-valve resins

    NASA Technical Reports Server (NTRS)

    Colombo, G. V.; Putnam, D. F.

    1980-01-01

    Improved microbial-check-valve resins have been tested for their microbicidal effectiveness and long-term stability. Resins give more-stable iodine concentrations than previous preparations and do not impart objectionable odor or taste to treated water. Microbial check valve is small cylindrical device, packed with iodide-saturated resin, that is installed in water line where contamination by micro-organisms is to be prevented. Prototype microbial check valve was tested for stability and performance under harsh environmental conditions. Effectiveness was 100 percent at 35 deg, 70 deg, and 160 deg F (2 deg, 21 deg, and 71 deg C).

  4. Properties of a nanodielectric cryogenic resin

    SciTech Connect

    Polyzos, Georgios; Tuncer, Enis; Sauers, Isidor; More, Karren Leslie

    2010-01-01

    Physical properties of a nanodielectric composed of in situ synthesized titanium dioxide (TiO{sub 2}) nanoparticles ({le} 5 nm in diameter) and a cryogenic resin are reported. The dielectric losses were reduced by a factor of 2 in the nanocomposite, indicating that the presence of small TiO{sub 2} nanoparticles restricted the mobility of the polymer chains. Dielectric breakdown data of the nanodielectric was distributed over a narrower range than that of the unfilled resin. The nanodielectric had 1.56 times higher 1% breakdown probability than the resin, yielding 0.64 times thinner insulation thickness for the same voltage level, which is beneficial in high voltage engineering.

  5. Chemical Characterization of Phenol/Formaldehyde Resins

    NASA Technical Reports Server (NTRS)

    Brayden, T. H.

    1986-01-01

    Report discusses tests of commercial phenol/formaldehyde resins to establish relationships among composition before use, behavior during curing, and strength after curing. Resin used in carbon/carbon laminates. In curing process, two molecules of phenol joined together in sequence of reactions involving molecule of formaldehyde. Last step of sequence, molecule of water released. Sequence repeats until one of ingredients used up, leaving solidified thermoset plastic. Issues to be resolved: number and relative abundances of ingredients, presence of certain chemical groups, heat-producing ability of resin, and range of molecular weights present.

  6. Mesoscopic electronics beyond DC transport

    NASA Astrophysics Data System (ADS)

    di Carlo, Leonardo

    Since the inception of mesoscopic electronics in the 1980's, direct current (dc) measurements have underpinned experiments in quantum transport. Novel techniques complementing dc transport are becoming paramount to new developments in mesoscopic electronics, particularly as the road is paved toward quantum information processing. This thesis describes seven experiments on GaAs/AlGaAs and graphene nanostructures unified by experimental techniques going beyond traditional dc transport. Firstly, dc current induced by microwave radiation applied to an open chaotic quantum dot is investigated. Asymmetry of mesoscopic fluctuations of induced current in perpendicular magnetic field is established as a tool for separating the quantum photovoltaic effect from classical rectification. A differential charge sensing technique is next developed using integrated quantum point contacts to resolve the spatial distribution of charge inside a double quantum clot. An accurate method for determining interdot tunnel coupling and electron temperature using charge sensing is demonstrated. A two-channel system for detecting current noise in mesoscopic conductors is developed, enabling four experiments where shot noise probes transmission properties not available in dc transport and Johnson noise serves as an electron thermometer. Suppressed shot noise is observed in quantum point contacts at zero parallel magnetic field, associated with the 0.7 structure in conductance. This suppression evolves with increasing field into the shot-noise signature of spin-lifted mode degeneracy. Quantitative agreement is found with a phenomenological model for density-dependent mode splitting. Shot noise measurements of multi-lead quantum-dot structures in the Coulomb blockade regime distill the mechanisms by which Coulomb interaction and quantum indistinguishability correlate electron flow. Gate-controlled sign reversal of noise cross correlation in two capacitively-coupled dots is observed, and shown to

  7. Dilation and Curettage (D&C)

    MedlinePlus

    ... Advocacy For Patients About ACOG Dilation and Curettage (D&C) Home For Patients Search FAQs Dilation and ... FAQ062, February 2016 PDF Format Dilation and Curettage (D&C) Special Procedures What is dilation and curettage ( ...

  8. Cobalt Ions Improve the Strength of Epoxy Resins

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St. Clair, A. K.

    1986-01-01

    Technique developed for improving mechanical strength of epoxy resins by adding cobalt ions in form of tris(acetylacetonato)cobalt (III) complex. Solid cast disks prepared from cobalt ion-containing epoxy resins tested for flexural strength and stiffness. Incorporation of cobalt ions into epoxies increased flexural strength of resins by 10 to 95 percent. Suitable resins for this technique include any liquid or solid TGMDA resins. Improved epoxy formulation proves useful as composite matrix resin, adhesive, or casting resin for applications on commercial and advanced aircraft.

  9. Optimal depth of cure for nanohybrid resin composite using quartz tungsten halogen and new high intensity light-emitting diode curing units.

    PubMed

    Tanthanuch, Saijai; Ruengsri, Prapansri; Kukiattrakoon, Boonlert

    2013-08-01

    This study sought to evaluate the effects of quartz tungsten halogen (QTH) and light-emitting diode (LED) photocuring units on the degree of conversion (DC) and surface microhardness of a resin composite that had been cured for optimal depth of cure (DoC) assessment. Two hundred and forty cylindrical specimens (4.0 mm in diameter, 2.0-4.0 mm thick) of shade A2 resin composite were prepared and cured with either a QTH or an LED. The DC and top and bottom surface hardness were recorded, and data were analyzed using 2-way ANOVA, Tukey's test, t-test (α = 0.05) and linear regression analysis. The results showed that surface microhardness values and DC were affected by light intensity (P < 0.01), and resin composite thickness (2, 3, and 4 mm) (P < 0.01). Resin composite polymerized by the QTH had an optimal DoC of 3 mm, compared to 4 mm for the LED. PMID:23928448

  10. Hydraulic Permeability of Resorcinol-Formaldehyde Resin

    SciTech Connect

    Taylor, Paul Allen

    2010-01-01

    An ion exchange process using spherical resorcinol-formaldehyde (RF) resin is the baseline process for removing cesium from the dissolved salt solution in the high-level waste tanks at the Hanford Site, using large scale columns as part of the Waste Treatment Plant (WTP). The RF resin is also being evaluated for use in the proposed small column ion exchange (SCIX) system, which is an alternative treatment option at Hanford and at the Savannah River Site (SRS). A recirculating test loop with a small ion exchange column was used to measure the effect of oxygen uptake and radiation exposure on the permeability of a packed bed of the RF resin. The lab-scale column was designed to be prototypic of the proposed Hanford columns at the WTP. Although the test equipment was designed to model the Hanford ion exchange columns, the data on changes in the hydraulic permeability of the resin will also be valuable for determining potential pressure drops through the proposed SCIX system. The superficial fluid velocity in the lab-scale test (3.4-5.7 cm/s) was much higher than is planned for the full-scale Hanford columns to generate the maximum pressure drop expected in those columns (9.7 psig). The frictional drag from this high velocity produced forces on the resin in the lab-scale tests that matched the design basis of the full-scale Hanford column. Any changes in the resin caused by the radiation exposure and oxygen uptake were monitored by measuring the pressure drop through the lab-scale column and the physical properties of the resin. Three hydraulic test runs were completed, the first using fresh RF resin at 25 C, the second using irradiated resin at 25 C, and the third using irradiated resin at 45 C. A Hanford AP-101 simulant solution was recirculated through a test column containing 500 mL of Na-form RF resin. Known amounts of oxygen were introduced into the primary recirculation loop by saturating measured volumes of the simulant solution with oxygen and reintroducing

  11. DC-Powered Jumping Ring

    NASA Astrophysics Data System (ADS)

    Jeffery, Rondo N.; Amiri, Farhang

    2016-02-01

    The classroom jumping ring demonstration is nearly always performed using alternating current (AC), in which the ring jumps or flies off the extended iron core when the switch is closed. The ring jumps higher when cooled with liquid nitrogen (LN2). We have performed experiments using DC to power the solenoid and find similarities and significant differences from the AC case. In particular, the ring does not fly off the core but rises a short distance and then falls back. If the ring jumps high enough, the rising and the falling motion of the ring does not follow simple vertical motion of a projectile. This indicates that there are additional forces on the ring in each part of its motion. Four possible stages of the motion of the ring with DC are identified, which result from the ring current changing directions during the jump in response to a changing magnetic flux through the moving ring.

  12. dc-free coset codes

    NASA Technical Reports Server (NTRS)

    Deng, Robert H.; Herro, Mark A.

    1988-01-01

    A class of block coset codes with disparity and run-length constraints are studied. They are particularly well suited for high-speed optical fiber links and similar channels, where dc-free pulse formats, channel error control, and low-complexity encoder-decoder implementations are required. The codes are derived by partitioning linear block codes. The encoder and decoder structures are the same as those of linear block codes with only slight modifications. A special class of dc-free coset block codes are derived from BCH codes with specified bounds on minimum distance, disparity, and run length. The codes have low disparity levels (a small running digital sum) and good error-correcting capabilities.

  13. Washington: A DC Circuit Tour

    NASA Astrophysics Data System (ADS)

    Halpern, Paul

    2010-12-01

    I explore the history of physics in Washington, D.C., and its environs through a tour of notable sites and personalities. Highlights include visits to the Smithsonian and Carnegie Institutions, stops at the Einstein Memorial, George Washington University, the University of Maryland, and the American Center for Physics, and biographical sketches of physicists Joseph Henry, George Gamow, Edward Teller, and others who worked in the District of Columbia.

  14. Ecological benefits of dc power transmission

    SciTech Connect

    Kutuzova, N. B.

    2011-05-15

    The environmental effects of dc overhead transmission lines are examined. The major effects of ac and dc transmission lines are compared. Dc lines have advantages compared to ac lines in terms of electrical safety for people under the lines, biological effects, corona losses, and clearance width.

  15. Dental repair material: a resin-modified glass-ionomer bioactive ionic resin-based composite.

    PubMed

    Croll, Theodore P; Berg, Joel H; Donly, Kevin J

    2015-01-01

    This report documents treatment and repair of three carious teeth that were restored with a new dental repair material that features the characteristics of both resin-modified glass-ionomer restorative cement (RMGI) and resin-based composite (RBC). The restorative products presented are reported by the manufacturer to be the first bioactive dental materials with an ionic resin matrix, a shock-absorbing resin component, and bioactive fillers that mimic the physical and chemical properties of natural teeth. The restorative material and base/liner, which feature three hardening mechanisms, could prove to be a notable advancement in the adhesive dentistry restorative materials continuum. PMID:25822408

  16. Phenoxy resins containing pendent ethynyl groups and cured resins obtained therefrom

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M. (Inventor)

    1985-01-01

    Phenoxy resins containing pendent ethynyl groups, the process for preparing the same, and the cured resin products obtained therefrom are disclosed. Upon the application of heat, the ethynyl groups react to provide branching and crosslinking with the cure temperature being lowered by using a catalyst if desired but not required. The cured phenoxy resins containing pendent ethynyl groups have improved solvent resistance and higher use temperature than linear uncrosslinked phenoxy resins and are applicable for use as coatings, films, adhesives, composited matrices and molding compounds.

  17. Method for regenerating magnetic polyamine-epichlorohydrin resin

    DOEpatents

    Kochen, Robert L.; Navratil, James D.

    1997-07-29

    Magnetic polymer resins capable of efficient removal of actinides and heavy metals from contaminated water are disclosed together with methods for making, using, and regenerating them. The resins comprise polyamine-epichlorohydrin resin beads with ferrites attached to the surfaces of the beads. Markedly improved water decontamination is demonstrated using these magnetic polymer resins of the invention in the presence of a magnetic field, as compared with water decontamination methods employing ordinary ion exchange resins or ferrites taken separately.

  18. Method for regenerating magnetic polyamine-epichlorohydrin resin

    DOEpatents

    Kochen, R.L.; Navratil, J.D.

    1997-07-29

    Magnetic polymer resins capable of efficient removal of actinides and heavy metals from contaminated water are disclosed together with methods for making, using, and regenerating them. The resins comprise polyamine-epichlorohydrin resin beads with ferrites attached to the surfaces of the beads. Markedly improved water decontamination is demonstrated using these magnetic polymer resins of the invention in the presence of a magnetic field, as compared with water decontamination methods employing ordinary ion exchange resins or ferrites taken separately. 9 figs.

  19. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... Butyrates Cellulose Acetate Resin *Cellulose Acetates *Cellulose Acetates Propionates Cellulose Nitrate... Polymers Nylon 11 Resin *Nylon 6-66 Copolymers *Nylon 6—Nylon 11 Blends Nylon 6 Resin Nylon 612 Resin...

  20. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... Butyrates Cellulose Acetate Resin *Cellulose Acetates *Cellulose Acetates Propionates Cellulose Nitrate... Polymers Nylon 11 Resin *Nylon 6-66 Copolymers *Nylon 6—Nylon 11 Blends Nylon 6 Resin Nylon 612 Resin...

  1. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... Butyrates Cellulose Acetate Resin *Cellulose Acetates *Cellulose Acetates Propionates Cellulose Nitrate... Polymers Nylon 11 Resin *Nylon 6-66 Copolymers *Nylon 6—Nylon 11 Blends Nylon 6 Resin Nylon 612 Resin...

  2. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... Butyrates Cellulose Acetate Resin *Cellulose Acetates *Cellulose Acetates Propionates Cellulose Nitrate... Polymers Nylon 11 Resin *Nylon 6-66 Copolymers *Nylon 6—Nylon 11 Blends Nylon 6 Resin Nylon 612 Resin...

  3. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... Butyrates Cellulose Acetate Resin *Cellulose Acetates *Cellulose Acetates Propionates Cellulose Nitrate... Polymers Nylon 11 Resin *Nylon 6-66 Copolymers *Nylon 6—Nylon 11 Blends Nylon 6 Resin Nylon 612 Resin...

  4. Improved high-temperature resistant matrix resins

    NASA Technical Reports Server (NTRS)

    Green, H. E.; Chang, G. E.; Wright, W. F.; Ueda, K.; Orell, M. K.

    1989-01-01

    A study was performed with the objective of developing matrix resins that exhibit improved thermo-oxidative stability over state-of-the-art high temperature resins for use at temperatures up to 644 K (700 F) and air pressures up to 0.7 MPa (100 psia). The work was based upon a TRW discovered family of polyimides currently licensed to and marketed by Ethyl Corporation as EYMYD(R) resins. The approach investigated to provide improved thermo-oxidative properties was to use halogenated derivatives of the diamine, 2, 2-bis (4-(4-aminophenoxy)phenyl) hexafluoropropane (4-BDAF). Polyimide neat resins and Celion(R) 12,000 composites prepared from fluorine substituted 4-BDAF demonstrated unexpectedly lower glass transition temperatures (Tg) and thermo-oxidative stabilities than the baseline 4-BDAF/PMDA polymer.

  5. Silicone modified resins for graphite fiber laminates

    NASA Technical Reports Server (NTRS)

    Frost, L. W.; Bower, G. M.

    1979-01-01

    The development of silicon modified resins for graphite fiber laminates which will prevent the dispersal of graphite fibers when the composites are burned is discussed. Eighty-five silicone modified resins were synthesized and evaluated including unsaturated polyesters, thermosetting methacrylates, epoxies, polyimides, and phenolics. Neat resins were judged in terms of Si content, homogeneity, hardness, Char formation, and thermal stability. Char formation was estimated by thermogravimetry to 1,000 C in air and in N2. Thermal stability was evaluated by isothermal weight loss measurements for 200 hrs in air at three temperatures. Four silicone modified epoxies were selected for evaluation in unidirectional filament wound graphite laminates. Neat samples of these resins had 1,000 C char residues of 25 to 50%. The highest flexural values measured for the laminates were a strength of 140 kpsi and a modulus of 10 Mpsi. The highest interlaminar shear strength was 5.3 kpsi.

  6. Synthesis of improved phenolic and polyester resins

    NASA Technical Reports Server (NTRS)

    Delano, C. B.

    1980-01-01

    Thirty-seven cured phenolic resin compositions were prepared and tested for their ability to provide improved char residues and moisture resistance over state of the art epoxy resin composite matrices. Cyanate, epoxy novolac and vinyl ester resins were investigated. Char promoter additives were found to increase the anaerobic char yield at 800 C of epoxy novolacs and vinyl esters. Moisture resistant cyanate and vinyl ester compositions were investigated as composite matrices with Thornel 300 graphite fiber. A cyanate composite matrix provided state of the art composite mechanical properties before and after humidity exposure and an anaerobic char yield of 46 percent at 800 C. The outstanding moisture resistance of the matrix was not completely realized in the composite. Vinyl ester resins showed promise as candidates for improved composite matrix systems.

  7. 21 CFR 177.1550 - Perfluorocarbon resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... articles intended for repeated use in contact with food. (d) Specifications—(1) Infrared identification. Perfluorocarbon resins can be identified by their characteristic infrared spectra. (2) Melt-viscosity. (i) The...

  8. Determining resin/fiber content of laminates

    NASA Technical Reports Server (NTRS)

    Garrard, G. G.; Houston, D. W.

    1979-01-01

    Article discusses procedure where hydrazine is used to extract graphite fibers from cured polyimide resin. Method does not attack graphite fibers and is faster than hot-concentrated-acid digestion process.

  9. 21 CFR 872.3140 - Resin applicator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... applicator is a brushlike device intended for use in spreading dental resin on a tooth during application of tooth shade material. (b) Classification. Class I (general controls). The device is exempt from...

  10. 21 CFR 872.3140 - Resin applicator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... applicator is a brushlike device intended for use in spreading dental resin on a tooth during application of tooth shade material. (b) Classification. Class I (general controls). The device is exempt from...

  11. 21 CFR 872.3140 - Resin applicator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... applicator is a brushlike device intended for use in spreading dental resin on a tooth during application of tooth shade material. (b) Classification. Class I (general controls). The device is exempt from...

  12. 21 CFR 872.3140 - Resin applicator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... applicator is a brushlike device intended for use in spreading dental resin on a tooth during application of tooth shade material. (b) Classification. Class I (general controls). The device is exempt from...

  13. 21 CFR 872.3140 - Resin applicator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... applicator is a brushlike device intended for use in spreading dental resin on a tooth during application of tooth shade material. (b) Classification. Class I (general controls). The device is exempt from...

  14. Radiation testing of organic ion exchange resins

    SciTech Connect

    Carlson, C.D.; Bray, L.A.; Bryan, S.A.

    1995-09-01

    A number of ion exchange materials are being evaluated as part of the Tank Waste Remediation System (TWRS) Pacific Northwest Laboratory (PNL) Pretreatment Project for the removal of {sup 137}Cs from aqueous tank wastes. Two of these materials are organic resins; a phenol-formaldehyde resin (Duolite CS-100) produced by Rohm and Haas Co. (Philadelphia, Pennsylvania) and a resorcinol-formaldehyde (RF) resin produced by Boulder Scientific Co. (Mead, Colorado). One of the key parameters in the assessment of the organic based ion exchange materials is its useful lifetime in the radioactive and chemical environment that will be encountered during waste processing. The focus of the work presented in this report is the radiation stability of the CS-100 and the RF resins. The scope of the testing included one test with a sample of the CS-100 resin and testing of two batches of the RF resin (BSC-187 and BSC-210). Samples of the exchangers were irradiated with a {sup 60}Co source to a total absorbed dose of 10{sup 9} R over a period of 5 months in a static (no flow) and a flowing configuration with neutralized current acid waste (NCAW) simulant as a feed. Based on a maximum concentration of {sup 137}Cs on the resin that would result from processing NCAW, this dose represents an operational period of at least 150 days for the RF resin and at least 1260 days for the CS-100 resin. Gas generation in the static experiment was continuously monitored and G values (molecules of gas per 100 eV) were determined for each species. Resin samples were obtained periodically and the equilibrium behavior of the resins was assessed by determining the distribution coefficients (K{sub d}s). Structural information was also obtained by {sup 13}C cross polarization magic angle (CPMAS) nuclear magnetic resonance (NMR) spectrometry and Fourier Transform Infrared (FTIR) spectroscopy so that changes to the chemical structure could be correlated with changes in K{sub d}.

  15. 76 FR 68745 - DC Energy, LLC; DC Energy Mid-Atlantic, LLC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission DC Energy, LLC; DC Energy Mid-Atlantic, LLC v. PJM Interconnection, L.L.C... Federal Energy Regulatory Commission (Commission), 18 CFR 385.206 (2011), DC Energy, LLC (DC Energy)...

  16. Advanced DC/DC Converters towards higher Volumetric Efficiencies for Space Applications

    NASA Technical Reports Server (NTRS)

    Plante, Jeannette; Shue, Jack; Liu, David; Wang, Bright; Shaw, Harry

    2005-01-01

    Contents include the following: 1. NASA mission outlook. 2. Issues with DC/DC converter for space. 3. Statement of newly initiated engineering activities for DC/DC converter. 4. Overview of prototyping work with novel materials. 5. Results of cryogenic testing.

  17. Full wave dc-to-dc converter using energy storage transformers

    NASA Technical Reports Server (NTRS)

    Moore, E. T.; Wilson, T. G.

    1969-01-01

    Full wave dc-to-dc converter, for an ion thrustor, uses energy storage transformers to provide a method of dc-to-dc conversion and regulation. The converter has a high degree of physical simplicity, is lightweight and has high efficiency.

  18. Cesium-specific phenolic ion exchange resin

    DOEpatents

    Bibler, Jane P.; Wallace, Richard M.

    1995-01-01

    A phenolic, cesium-specific, cation exchange resin is prepared by neutralizing resorcinol with potassium hydroxide, condensing/polymerizing the resulting intermediate with formaldehyde, heat-curing the resulting polymer to effect cross-linking and grinding it to desired particle size for use. This resin will selectively and efficiently adsorb cesium ions in the presence of a high concentration of sodium ions with a low carbon to cesium ratio.

  19. Cesium-specific phenolic ion exchange resin

    DOEpatents

    Bibler, J.P.; Wallace, R.M.

    1995-08-15

    A phenolic, cesium-specific, cation exchange resin is prepared by neutralizing resorcinol with potassium hydroxide, condensing/polymerizing the resulting intermediate with formaldehyde, heat-curing the resulting polymer to effect cross-linking and grinding it to desired particle size for use. This resin will selectively and efficiently adsorb cesium ions in the presence of a high concentration of sodium ions with a low carbon to cesium ratio. 2 figs.

  20. Dual and self-curing potential of self-adhesive resin cements as thin films.

    PubMed

    Moraes, R R; Boscato, N; Jardim, P S; Schneider, L F J

    2011-01-01

    In this study, the dual- and self-curing potential of self-adhesive resin cements (SARCs) as thin, clinically-relevant cement films was investigated. The SARCs tested were: BisCem (BSC; Bisco), Maxcem Elite (MXE; Kerr), RelyX Unicem clicker (UNI; 3M ESPE), seT capsule (SET; SDI), and SmartCem 2 (SC2; Dentsply Caulk). The conventional cement RelyX ARC (3M ESPE) was tested as a reference. The degree of conversion (DC) as a function of time was evaluated by real-time Fourier transform infrared spectroscopy with an attenuated total reflectance (ATR) device. The cements were either photoactivated for 40 seconds (dual-cure mode) or not photoactivated (self-cure mode). The cement film thickness was 50 ± 10 μm. The DC (%) was evaluated 1, 5, 10, 15, 20, 25, and 30 minutes after placing the cement on the ATR cell. Data for DC as a function of time were analyzed by two-way repeated measures analysis of variance (ANOVA). DC values at 30 minutes for the self- and dual-cure modes were submitted to one-way ANOVA. Post hoc comparisons were performed using the Student-Newman-Keuls test (p<0.05). The rate and the extent of conversion were lower for the SARCs compared with the conventional cement. Means ± standard deviations (SD) for the dual-cure mode at 30 minutes were: 75 ± 5 (ARC)a, 73 ± 8 (SET)a, 61 ± 4 (MXE)b, 51 ± 9 (BSC)c, 51 ± 4 (UNI)c, and 48 ± 3 (SC2)c, while in the self-cure mode means and SD were 62 ± 6 (ARC)a, 54 ± 3 (MXE)b, 40 ± 6 (SC2)c, 35 ± 2 (UNI)c, 35 ± 3 (SET)c, and 11 ± 3 (BSC)d. The DC for the dual-cure mode was generally higher than the self-cure, irrespective of the time. Discrepancies in DC between the dual- and self-cure modes from 11% to 79% were observed. In conclusion, SARCs may present slower rate of polymerization and lower final DC than conventional resin cements, in either the dual- or self-cure mode. PMID:21864125

  1. Cleanup of TMI-2 demineralizer resins

    SciTech Connect

    Bond, W.D.; King, L.J.; Knauer, J.B.; Hofstetter, K.J.; Thompson, J.D.

    1985-01-01

    Radiocesium is being removed from Demineralizers A and B (DA and DB by a process that was developed from laboratory tests on small samples of resin from the demineralizers. The process was designed to elute the radiocesium from the demineralizer resins and then to resorb it onto the zeolite ion exchangers contained in the Submerged Demineralizer System (SDS). The process was also required to limit the maximum cesium activities in the resin eluates (SDS feeds) so that the radiation field surrounding the pipelines would not be excessive. The process consists of 17 stages of batch elution. In the initial stage, the resin is contacted with 0.18 M boric acid. Subsequent stages subject the resin to increasing concentrations of sodium in NaH/sub 2/BO/sub 3/-H/sub 3/BO/sub 3/ solution (total B = 0.35 M) and then 1 M sodium hydroxide in the final stages. Results on the performance of the process in the cleanup of the demineralizers at TMI-2 are compared to those obtained from laboratory tests with small samples of the DA and DB resins. To date, 15 stages of batch elution have been completed on the demineralizers at TMI-2 which resulted in the removal of about 750 Ci of radiocesium from DA and about 3300 Ci from DB.

  2. Ion Exchange Temperature Testing with SRF Resin

    SciTech Connect

    Russell, Renee L.; Rinehart, Donald E.; Brown, Garrett N.; Peterson, Reid A.

    2012-03-01

    Ion exchange using the Spherical Resorcinol-Formaldehyde (SRF) resin has been selected by the U.S. Department of Energy’s Office of River Protection for use in the Pretreatment Facility of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) and for potential application in an at-tank deployment for removing 137Cs. Recent proposed changes to the WTP ion exchange process baseline indicate that higher temperatures (50°C) to alleviate post-filtration precipitation issues prior to reaching the ion exchange columns may be required. Therefore, it is important to understand the behavior of SRF resin performance under the conditions expected with the new equipment and process changes. This research examined the impact of elevated temperature on resin loading and resin degradation during extended solution flow using elevated temperature (45°, 50°, 55°, 60°, 65°, 75°C). Testing for extended times at elevated temperatures showed that the resin does degrade and loading capacity is reduced at and above 45°C. Above 60°C the resin appears to not load at all.

  3. Imide modified epoxy matrix resins

    NASA Technical Reports Server (NTRS)

    Scola, D. A.

    1984-01-01

    The results of a program designed to develop tough imide modified epoxy resins cured by bisimide amine (BIA) hardeners are described. State-of-the-art epoxides MY720 and DER383 were used, and four bismide amines were evaluated. These were the BIA's derived from the 6F anhydride (4,4'-(hexafluoroisopropylidene) bis(phthalic anhydride) and the diamines 3,3'-diaminodiphynyl sulfone, 4,4'-oxygianiline, 4,4'-methylene dianiline, and 1,12-dodecane diamine. A key intermediate, designated 6F anhydride, is required for the synthesis of the bisimide amines. Reaction parameters to synthesize a precursor to the 6F anhydride (6FHC) in high yields were investigated. The catalyst trifluoromethane sulfonic acid was studied. Although small scale runs yielded the 6FHC in 50 percent yield, efforts to ranslate these results to a larger scale synthesis gave the 6FHC in only 9 percent yield. Results show that the concept of using bisimide amine as curing agents to improve the toughness properties of epoxies is valid.

  4. Preparation and cured properties of novel cycloaliphatic epoxy resins

    SciTech Connect

    Tokizawa, Makoto; Okada, Hiroyoshi; Wakabayashi, Nobukatsu; Kimura, Tomiaki . Research Center)

    1993-10-20

    Preparation and characterization of novel cycloaliphatic epoxy resins, which are derived from octadienyl compounds, were studied. From a model peracetic acid epoxidation reaction using 2,7-octadienyl acetate-1, the structure of the liquid resins is estimated to be mainly terminal epoxides and some amount of inner epoxide depending on the epoxide content. The epoxy resins offer lower toxicity and lower vapor pressure. The reactivity of the resin with acid anhydrides is moderate but faster than that of traditional cyclohexane epoxide-type resins and slower than that of the glycidyl ester-type resins. This reactivity was also examined using model compounds. The heat deflection temperature of the hexahydro-phthalic anhydride-cured resins is shown to be directly proportional to the number of epoxy groups in the molecules. The flexural strength of the cured resins is nearly equivalent to that of the commercial resins, although the flexural elongation of the resins is larger than that of the rigid cyclohexane epoxide-type resins. The thermal stability of the cured resins is compared to typical rigid cycloaliphatic resins; furthermore, high water resistance of the cured resins is suggested to be attributed to the hydrophobic character of the C[sub 8] chain by cross-linking.

  5. Tc-99 Ion Exchange Resin Testing

    SciTech Connect

    Valenta, Michelle M.; Parker, Kent E.; Pierce, Eric M.

    2010-08-01

    Pacific Northwest National Laboratory was contracted by CHPRC to evaluate the release of 99Tc from spent resin used to treat water from well 299-W15-765 and stored for several years. The key questions to be answered are: 1) does 99Tc readily release from the spent ion exchange resin after being in storage for several years; 2) if hot water stripping is used to remove the co-contaminant carbon tetrachloride, will 99Tc that has been sequestered by the resin be released; and 3) can spent resin be encapsulated into a cementitious waste form; if so, how much 99Tc would be released from the weathering of the monolith waste form? The results from the long term stability leach test results confirm that the resin is not releasing a significant amount of the sequestered 99Tc, evident by the less than 0.02% of the total 99Tc loaded being identified in the solution. Furthermore, it is possible that the measured 99Tc concentration is the result of 99Tc contained in the pore spaces of the resin. In addition to these results, analyses conducted to examine the impact of hot water on the release of 99Tc suggest that only a small percentage of the total is being released. This suggest that hot water stripping to remove carbon tetrachloride will not have a significant affect on the resin’s ability to hold-on to sequestered 99Tc. Finally, encapsulation of spent resin in a cementitious material may be a viable disposal option, but additional tests are needed to examine the extent of physical degradation caused by moisture loss and the effect this degradation process can have on the release of 99Tc.

  6. Degree of conversion of two dual-cured resin cements light-irradiated through zirconia ceramic disks

    PubMed Central

    Kim, Min-Jeong; Kim, Kyo-Han; Kim, Young-Kyung

    2013-01-01

    PURPOSE The aim of this Fourier transform infrared (FTIR) spectroscopic study was to measure the degree of conversion (DC) of dual-cured resin cements light-irradiated through zirconia ceramic disks with different thicknesses using various light-curing methods. MATERIALS AND METHODS Zirconia ceramic disks (KT12) with three different thicknesses (1.0, 2.0, and 4.0 mm) were prepared. The light transmittance of the disks was measured using ultraviolet visible near-infrared spectroscopy. Four different light-curing protocols were used by combining two curing light modes (Elipar TriLight (standard mode) and bluephase G2 (high power mode)) with light-exposure times of 40 and 120 seconds. The DCs of the two dual-cured resin cements (Duo-Link and Panavia F2.0) light-irradiated through the disks was analyzed at three time intervals (3, 7, and 10 minutes) by FTIR spectroscopy. The data was analyzed using repeated measures ANOVA (α=.05).Two-way ANOVA and Tukey post hoc test were used to analyze the 10 minute DC results. RESULTS The 1.0 mm thick disk exhibited low light transmittance (<25%), and the transmittance decreased considerably with increasing disk thickness. All groups exhibited significantly higher 10 minute DC values than the 3 or 7 minute values (P<.05), but some exceptions were observed in Duo-Link. Two-way ANOVA revealed that the influence of the zirconia disk thickness on the 10 minute DC was dependent on the light-curing methods (P<.001). This finding was still valid even at 4.0 mm thickness, where substantial light attenuation took place. CONCLUSION The curing of the dual-cured resin cements was affected significantly by the light-curing technique, even though the additional chemical polymerization mechanism worked effectively. PMID:24353887

  7. Resin flow monitoring in vacuum-assisted resin transfer molding using optical fiber distributed sensor

    NASA Astrophysics Data System (ADS)

    Eum, Soohyun; Kageyama, Kazuro; Murayama, Hideaki; Ohsawa, Isamu; Uzawa, Kiyoshi; Kanai, Makoto; Igawa, Hirotaka

    2007-04-01

    In this study, we implemented resin flow monitoring by using an optical fiber sensor during vacuum assisted resin transfer molding (VaRTM).We employed optical frequency domain reflectometry (OFDR) and fiber Bragg grating (FBG) sensor for distributed sensing. Especially, long gauge FBGs (about 100mm) which are 10 times longer than an ordinary FBG were employed for more effective distributed sensing. A long gauge FBG was embedded in GFRP laminates, and other two ones were located out of laminate for wavelength reference and temperature compensation, respectively. During VaRTM, the embedded FBG could measure how the preform affected the sensor with vacuum pressure and resin was flowed into the preform. In this study, we intended to detect the gradient of compressive strain between impregnated part and umimpregnated one within long gauge FBG. If resin is infused to preform, compressive strain which is generated on FBG is released by volume of resin. We could get the wavelength shift due to the change of compressive strain along gauge length of FBG by using short-time Fourier transformation for signal acquired from FBG. Therefore, we could know the resin flow front with the gradient of compressive strain of FBG. In this study, we used silicon oil which has same viscosity with resin substitute for resin in order to reuse FBG. In order to monitor resin flow, the silicon oil was infused from one edge of preform, the silicon oil was flowed from right to left. Then, we made dry spot within gauge length by infusing silicon oil to both sides of preform to prove the ability of dry spot monitoring with FBG. We could monitor resin flow condition and dry spot formation successfully using by FBG based on OFDR.

  8. Effect of modulated photo-activation on polymerization shrinkage behavior of dental restorative resin composites.

    PubMed

    Tauböck, Tobias T; Feilzer, Albert J; Buchalla, Wolfgang; Kleverlaan, Cornelis J; Krejci, Ivo; Attin, Thomas

    2014-08-01

    This study investigated the influence of modulated photo-activation on axial polymerization shrinkage, shrinkage force, and hardening of light- and dual-curing resin-based composites. Three light-curing resin composites (SDR bulk-fill, Esthet X flow, and Esthet X HD) and one dual-curing material (Rebilda DC) were subjected to different irradiation protocols with identical energy density (27 J cm(-2) ): high-intensity continuous light (HIC), low-intensity continuous light (LIC), soft-start (SS), and pulse-delay curing (PD). Axial shrinkage and shrinkage force of 1.5-mm-thick specimens were recorded in real time for 15 min using custom-made devices. Knoop hardness was determined at the end of the observation period. Statistical analysis revealed no significant differences among the curing protocols for both Knoop hardness and axial shrinkage, irrespective of the composite material. Pulse-delay curing generated the significantly lowest shrinkage forces within the three light-curing materials SDR bulk-fill, Esthet X flow, and Esthet X HD. High-intensity continuous light created the significantly highest shrinkage forces within Esthet X HD and Rebilda DC, and caused significantly higher forces than LIC within Esthet X flow. In conclusion, both the composite material and the applied curing protocol control shrinkage force formation. Pulse-delay curing decreases shrinkage forces compared with high-intensity continuous irradiation without affecting hardening and axial polymerization shrinkage. PMID:25039287

  9. Single event AC - DC electrospraying

    NASA Astrophysics Data System (ADS)

    Stachewicz, U.; Dijksman, J. F.; Marijnissen, J. C. M.

    2008-12-01

    Electrospraying is an innovative method to deposit very small amounts of, for example, biofluids (far less than 1 p1) that include DNA or protein molecules. An electric potential is applied between a nozzle filled with liquid and a counter electrode placed at 1-2 millimeter distance from the nozzle. In our set-up we use an AC field superposed on a DC field to control the droplet generation process. Our approach is to create single events of electrospraying triggered by one single AC pulse. During this pulse, the equilibrium meniscus (determined by surface tension, static pressure and the DC field) of the liquid changes rapidly into a cone and subsequently into a jet formed at the cone apex. Next, the jet breaks-up into fine droplets and the spraying stops. The meniscus returns to its equilibrium shape again. So far we obtained a stable and reproducible single event process for ethanol and ethylene glycol with water using glass pipettes. The results will be used to generate droplets on demand in a controlled way and deposit them on a pre-defined place on the substrate.

  10. Polymerization characteristics of EMA-based resin.

    PubMed

    Saito, Yuji

    2004-03-01

    To explore the feasibility of a new relining material, polymerization characteristics such as peak temperature, setting time, residual monomer, and postpolymerization were examined in ethyl methacrylate (EMA) resins composed of EMA and 4 kinds of EMA/methyl methacrylate (MMA) copolymers with high and low molecular weights and initiated by benzoyl peroxide/N,N-dimethyl-p-toluidine system and compared with those of MMA/PMMA resins. Peak temperature (53.8-71.0 degrees C) and residual monomer (2.56-3.52% after 1 h and 1.57-2.31% after 24 h) of the EMA resins were significantly lower than those of the MMA resins (88.9-93.4 degrees C and 4.61-5.85% after 1 h and 4.09-4.84% after 24 h, respectively). The composition of the copolymers had a significant effect on peak temperature and setting time but no significant effect on residual monomer and postpolymerization. The molecular weight of the copolymers affected peak temperature, setting time and residual monomer significantly. This study suggested that EMA resins are worthy of further evaluation as a relining material. PMID:15164919