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Sample records for epoxidized novolac resin

  1. Sub-70 nm resolution patterning of high etch-resistant epoxy novolac resins using gas permeable templates in ultraviolet nanoimprint lithography

    NASA Astrophysics Data System (ADS)

    Takei, Satoshi; Hanabata, Makoto

    2016-05-01

    This study aimed to expand the resolution limits of epoxy novolac resins that have enhanced etch resistance as one of the desirable resist properties for next-generation devices. Epoxy novolac resins have high etch resistance. However, because epoxy novolac resins are either solid or semisolid at room temperature, and because the use of volatile solvents in resist can be a cause of pattern failure in nanoimprint lithography, epoxy novolac resins have been of limited utility as resist. Excellent sub-70 nm resolution patterning can be achieved by diluting 15 wt % acetone in an ultraviolet nanoimprint lithography using gas-permeable templates.

  2. Structure and property relationships of fractionated novolac resins

    NASA Astrophysics Data System (ADS)

    Chen, K. Rex; Kwong, Ranee W.; Jordhamo, George M.; Allen, Robert D.; Gallagher-Wetmore, Paula M.

    1997-07-01

    In a previous paper, we described the performance of near- monodisperse novolak resins obtained through supercritical fluid extraction. The low molecular weight partner was found to be the key element for high contrast and high resolution of the reconstructed tandem resists. In this paper, we use 13C NMR spectroscopy to further explore the microstructure and the composition of each fraction. The results show that the percentage of ortho-ortho methylene bond (%o-o') remains relatively constant throughout all the fractions. However, the %o-o' unhindered CH2-bond is higher for the low molecular weight fraction than for that of the high molecular weight fraction. Also, the p-cresol to m-cresol ratio (p/m) is not constant among all the fractions. The p/m ratio of the lower MW fraction is greater than 2, then quickly reduces to 1 and then gradually decreases to 0.6. Since the %o-o' unhindered CH2- linkage is mainly the bond between p-cresol unit, it is expected to see that as the p/m ratio increases, the %o-o' unhindered bond increases. The good lithographic performance of some of the tandem resist described previously is closely related to this high ortho-ortho linkage. However, as the amount of low MW partner increases without corresponding adjustment of PAC loading, microgrooving is observed. We discuss the effect of PAC loading on the lithographic performance in these low molecular rich formulations.

  3. Lithographic performance and dissolution behavior of novolac resins for various developer surfactant systems

    NASA Astrophysics Data System (ADS)

    Flores, Gary E.; Loftus, James E.

    1992-06-01

    The use of surfactants in today's society ranges over a wide variety of technologies, from soaps and detergents to house paints and electronic materials. In the semiconductor industry, surfactants are commonly used as coating additives in photoresists, as additives in wet chemical etchants, as additives in developer solutions, and in other areas where surface activity is desirable. In most applications, the mechanisms of surfactant chemistry are well established, yet there has been only a limited amount of published literature pertaining to characterizing the behavior of surfactants in developer systems for photoresists. This project explores the application of surfactants in an aqueous tetramethyl ammonium hydroxide (TMAH) based developer for two optical resists, one incorporating a 2,1,4- diazonaphthoquinone (DNQ) sensitizer, while the other incorporates a 2,1,5-DNQ sensitizer. In addition, each optical resist is based on different positive novolac resins with distinct structural properties. This feature aids in illustrating the improtance of matching the developer surfactant with the photoresist resin structure. Four distinct non-ionic surfactants with well published physical and chemical properties are examined. Properties of the surfactants explored include differences in structure, surfactant concentration, various degrees of hydrophilic versus lipophilic content (known as the HLB, or hydrophilic - lipophilic balance), and the differences in reported critical micelle concentration (CMC). Previous research investigated the performance characteristics of the 2,1,5-DNQ for these four surfactants. This investigation is an extension of the previous project by next considering a significantly different photoresist. A discussion of potential mechanisms of the solubilization and wetting effects is utilized to promote an understanding of surfactant effects in resist/developer systems. Also, because of the extensive characterization involved in screening surfactants, a

  4. Toughening of epoxy resins by epoxidized soybean oil

    SciTech Connect

    Frischinger, I.; Dirlikov, S.

    1993-12-31

    Homogeneous mixtures of a liquid rubber based on prepolymers of epoxidized soybean oil with amines, diglycidyl ether of bisphenol A epoxy resins, and commercial diamines form, under certain conditions, two-phase thermosetting materials that consist of a rigid epoxy matrix and randomly distributed small rubbery soybean particles (0.1-5 {mu}m). These two-phase thermosets have improved toughness, similar to that of other rubber-modified epoxies, low water absorption, and low sodium content. In comparison to the unmodified thermosets, the two-phase thermosets exhibit slightly lower glass-transition temperatures and Young`s moduli, but their dielectric properties do not change. The epoxidized soybean oil is available at a price below that of commercial epoxy resins and appears very attractive for epoxy toughening on an industrial scale. 15 refs., 17 figs., 6 tabs.

  5. Production of carbonaceous adsorbents from agricultural by-products and novolac resin under a continuous countercurrent flow type pyrolysis operation.

    PubMed

    Ioannou, Z; Simitzis, J

    2013-02-01

    Carbonaceous adsorbents based on novolac resin (N) and olive stone biomass (B) in a proportion of 20/80 and 40/60 w./w. N/O were produced. The specimens were cured (c) and pyrolyzed/carbonized (C) up to 1000 °C under a continuous countercurrent flow type pyrolysis operation (N20B-cC, N40B-cC). Commercial activated carbon (AC) was used for comparison reasons. Methylene blue adsorption from its aqueous solutions onto the adsorbents and kinetic analysis were investigated. The specific surface area of adsorbents and the gross calorific values (GCV) of cured materials were determined. The results show that N40B-cC presents lower weight loss and shrinkage but higher methylene blue adsorption than N20B-cC. Pseudo-second order mechanism describes better methylene blue adsorption onto all adsorbents. The specific surface area of carbonaceous and the gross calorific values of cured materials follow the order: AC>N20B-cC>N40B-cC and N100-c>N40B-c>N20B-c>B respectively. Olive stone biomass may constitute a suitable precursor for the production of carbonaceous materials. PMID:23246760

  6. Epoxidized natural rubber toughened aqueous resole type liquefied EFB resin: Physical and chemical characterization

    NASA Astrophysics Data System (ADS)

    Amran, Umar Adli; Zakaria, Sarani; Chia, Chin Hua

    2013-11-01

    A preliminary study on the reaction between aqueous resole type resinified liquefied palm oil empty fruit bunches fibres (RLEFB) with epoxidized natural rubber (ENR). Liquefaction of empty fruit bunches (EFB) is carried out at different ratio of phenol to EFB (P:EFB). Resole type phenolic resin is prepared using sodium hydroxide (NaOH) as the catalyst with the ratio of liquefied EFB (LEFB) to formaldehyde (LEFB:F) of 1:1.8. 50% epoxidation of epoxidized natural rubber (ENR-50) is used to react with resole resin by mixing with ENR with aqueous resole resin. The cured resin is characterized with FT-IR and SEM. Aqueous system have been found to be unsuitable medium in the reaction between resin and ENR. This system produced a highly porous product when RLEFB/ENR resin is cured.

  7. Novel novolac resins produced from 2,6-bishydroxymethyl-p-cresol, p-cresol, and m-cresol: a method to more evenly distribute p-cresol units throughout a novolac resin

    NASA Astrophysics Data System (ADS)

    Jeffries, Alfred T., III; Brzozowy, David J.; Greene, Nancy N.; Kokubo, Tadayoshi; Tan, Shiro

    1993-09-01

    In an effort to improve the performance of positive resists by increasing the amounts of o,o- bonding, some m-/p-cresol novolacs were prepared in which a portion of the p-cresol was replaced by 2,6-bishydroxymethyl-p-cresol (BHMPC). This work distinguishes itself from earlier work in which BHMPC was the sole source of p-cresol. Fractionated BHMPC polymers were shown to incorporate more p-cresol into their higher molecular weight portions of the molecules. The parent novolacs possessed lower molecular weights and polydispersivities than conventional m-/p-cresol novolacs of the same composition. The lithographically acceptable polymers were evaluated on an 0.52 NA i-line stepper. The resists made from the fractionated BHMPC polymers exhibited a direct relationship between the amount of p-cresol in the higher molecular weight fractions and resolution. The reasons for the difference in performance are discussed in terms of the m-/p-cresol contents of the fractionated and unfractionated polymers as determined by carbon-13 nmr.

  8. Pilot scale production, characterization, and optimization of epoxidized vegetable oil-based resins

    NASA Astrophysics Data System (ADS)

    Monono, Ewumbua Menyoli

    Novel epoxidized sucrose soyate (ESS) resins perform much better than other vegetable oil-based resins; thus, they are of current interest for commercial scale production and for a wide range of applications in coatings and polymeric materials. However, no work has been published that successfully scaled-up the reaction above a 1 kg batch size. To achieve this goal, canola oil was first epoxidized at a 300 g scale to study the epoxidation rate and thermal profile at different hydrogen peroxide (H2O2) addition rates, bath temperatures, and reaction times. At least 83% conversion of double bonds to oxirane was achieved by 2.5 h, and the reaction temperature was 8-15 °C higher than the water bath temperature within the first 30-40 min of epoxidation. A 38 L stainless steel kettle was modified as a reactor to produce 10 kg of ESS. Twenty 7-10 kg batches of ESS were produced with an overall 87.5% resin yield and > 98% conversion after batch three. The conversion and resin quality were consistent across the batches due to the modifications on the reaction that improved mixing and reaction temperature control within 55-65 oC. The total production time was reduced from 8 to 4 days due to the fabrication of a 40 L separatory funnel for both washing and filtration. A math model was developed to optimize the epoxidation process. This was done by using the Box-Behnken design to model the conversion at various acetic acid, H2O2, and Amberlite ratios and at various reaction temperatures and times. The model had an adjusted R2 of 97.6% and predicted R2 of 96.8%. The model showed that reagent amounts and time can be reduced by 18% without compromising the desired conversion value and quality.

  9. Novel bio-based thermoset resins based on epoxidized vegetable oils for structural adhesives

    NASA Astrophysics Data System (ADS)

    Sivasubramanian, Shivshankar

    Conventional engineered wood composites are bonded for the most part through formaldehyde-based structural adhesives such as urea formaldehyde (UF), melamine formaldehyde (MF), phenol formaldehyde (PF) and resorcinol formaldehyde (RF). Formaldehyde is a known human carcinogen; the occupational exposure and emission after manufacturing of these binders is raising more and more concern. With increasing emphasis on environmental issues, there is clear incentive to replace these hazardous conventional formaldehyde-based binders with cco-friendly resins having similar properties but derived from renewable sources, bearing in mind the economics of the structural wood composite industry. In this thesis, the curing reaction of bio-derived epoxy thermosets with inexpensive, low-toxicity precursors, including polyimines and amino acids was investigated. Epoxidized linseed oil (ELO) and epoxidized soybean oil (ESO) were successfully crosslinked with both branched polyethyleneimine (PEI) and triethylenetetramine (fETA). Epoxidized castor oil (ECO) was crosslinked with polyethyleneimine (PEI), having different molecular weights. Curing conditions were optimized through solvent uptake and soluble fraction analysis. Finally, the mechanical properties of the optimized compositions of rigid bioepoxies were evaluated using dynamic mechanical rheological testing (DMRT). While not as stiff as conventional materials, optimized materials have sufficient room temperature moduli to show promise for coatings and as binders in engineered wood products.

  10. [Use of aluminum foil baths for embedding biological materials in epoxide resins].

    PubMed

    Agaev, Iu M; Merkulov, V A

    1975-11-01

    The baths intended for embedding the biological material into epoxide resins are made of aluminium foil, 0.1 mm thick, cut in the form of rectangles (13 X 18 mm). The rectangular foil plates are placed on a soft microporous rubber separator 30--40 mm thick and by means of a form with the base equal to 5 X 10 mm the baths are pressed down by 4 mm deep. The baths are stuck to the paper stripes by rubber cement to ensure easy handling and numeration. In the process of embedding and polymerization the paper stripes having the baths are placed in the exsiccator with P2O5 and thermostate on special aluminium stands. PMID:775710

  11. 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.

  12. Effect of annealing temperature of nano-sized BaFe12O19 in Novolac phenolic resin on microwave properties for use as EMI shielding material in X-band

    NASA Astrophysics Data System (ADS)

    Ozah, S.; Bhattacharyya, N. S.

    2013-01-01

    Nanosized barium ferrite (BaFe12O19) powders are synthesized using co-precipitation technique at three different annealing temperatures. The X-Ray Diffraction pattern indicates the presence of hexagonal structure for all the three samples. Transmission electron microscopy (TEM) shows the particles are hexagonal in shape. The synthesized BaFe12O19 powder samples are mechanically mixed with Novolac phenolic resin (NPR) with filler to polymer weight ratio of 30:60 to prepare pellets of BaFe12O19/NPR composites of dimensions, 10.38 mm x 22.94 mm x 4 mm. The complex permittivity, ɛr and complex permeability, μr of the developed samples are measured at X-band by Nicolson-Ross method using Agilent E8362C vector network analyzer. The effect of the annealing temperature on the complex permittivity and permeability in the X-band is studied. The maximum dielectric constant and permeability is obtained of the BaFe12O19/NPR composite with BaFe12O19 annealed at 9000C as 6 and 2 respectively. The composite is a good candidate for microwave absorption study.

  13. Dissolution kinetics of high-resolution novolac resists

    NASA Astrophysics Data System (ADS)

    Itoh, Katsuyuki; Yamanaka, Koji; Nozue, Hiroshi; Kasama, Kunihiko

    1991-06-01

    Dissolution kinetics, as well as the formation mechanism of a surface insoluble layer produced by dipping into TMAH (tetramethylammonium hydroxide) developer, have been investigated. In the previous paper, we mentioned that dissolution rate characteristics of high resolution novolac resist are clearly divided into three regions. To investigate this dissolution mechanism, we evaluated the temperature dependence of R (Dissolution rate) by changing the exposure dose, PAC (photoactive compound equals dissolution inhibitor) and the TMAH concentration. From Arrhenius Plots of these resist systems, it is considered that R is determined by two competitive reactions in the presence of TMAH; i.e., (a) the complex formation between PAC and novolac resin which produces dissolution inhibition effect, (b) TMAH induced deprotonation of phenolic hydroxy groups in novolac resin which accelerates the dissolution of the resist. Furthermore, we also describe the formation mechanism of a surface insoluble layer produced by dipping into a TMAH developer followed by water rinse, on the basis of the dissolution time of this layer (ts). The resist surface was also analyzed by using FT-IR (Fourier transform infrared spectroscopic measurement) and XPS (X-ray photoelectron spectroscopy). As a result, it was found that (a) water rinse is essential for the surface insoluble layer formation, (b) the ts value is not directly correlated with PAC accumulation in the resist surface and (c) the ts value becomes longer when the amount of penetrated TMAH into the resist increases. These results suggest that the surface insoluble layer is produced via water rinse of PAC-novolac complex described above.

  14. Thermochemical tests on resins: Char resistance of selected phenolic cured epoxides

    NASA Technical Reports Server (NTRS)

    Keck, F. L.

    1982-01-01

    Curing epoxy resins with novalac phenolic resins is a feasible approach for increasing intact char of the resin system. Char yields above 40% at 700 C were achieved with epoxy novalac (DEN 438)/novalac phenolic (BRWE 5833) resin systems with or without catalyst such as ethyl tri-phenyl phosphonium iodide. These char yields are comparable to commercially used epoxy resin systems like MY-720/DDS/BF3. Stable prepregs are easily made from a solvent solution of the epoxy/phenolic system and this provides a feasible process for fabrication of same into commercial laminates.

  15. Exploration of cardanol-based phenolated and epoxidized resins by size exclusion chromatography and MALDI mass spectrometry.

    PubMed

    Fouquet, Thierry; Puchot, Laura; Verge, Pierre; Bomfim, João A S; Ruch, David

    2014-09-16

    Cardanol and cardanol derivatives are among the most important biobased materials currently investigated in green chemistry, as renewable and promising building blocks in lieu of traditional raw materials from non renewable resources, in particular owing to the olefinic linkages on the C15 alkyl side-chain. Despite the increasing interest they arouse, analytical chemistry dedicated to cardanol and associated resins has been rarely reported in the literature, found even poorer when dealing with chromatography and mass spectrometry. In this work, a thorough molecular characterization was conducted using matrix assisted laser desorption ionization (MALDI) mass spectrometry, size exclusion chromatography (SEC), and SEC-MALDI coupling to gain insights into the composition of phenolated, epoxidized, and epoxidized phenolated cardanol. A nomenclature was proposed to properly describe the numerous species found in these materials, while simulations of the unsaturation patterns and their comparison with the detected patterns in MALDI-MS gave useful details about the phenolation treatment expected to occur on the polyunsaturated C15 side chain. Finally, the SEC-MALDI off-line coupling allowed SEC peaks to be deconvoluted by mass spectrometry and MALDI artefacts related to matrix adduction to be pointed out. PMID:25150696

  16. EPR investigations of gamma-irradiated novolacs

    NASA Astrophysics Data System (ADS)

    Schrödner, M.; Wünsche, P.; Lampe, I. v.

    EPR investigations of γ-irradiated phenol, p-chlorophenol, o-chlorophenol, 3,5-dichlorophenol and p-cresol novolac are presented. The elimination of a chlorine atom from the phenolic ring must be assumed in the case of chlorinated novolacs. The corresponding aryl radical could only be detected in the case of 3,5-dichlorophenol novolac in a large amount. Furthermore phenoxy and cyclohexadienyl radicals were found in the spectra. The radiation chemical as well as the resist sensitivity are enhanced by chlorination but there is no definite correlation between them.

  17. Jute fiber composites from coal, super clean coal, and petroleum vacuum residue-modified phenolic resin

    SciTech Connect

    Ahmaruzzaman, M.; Sharma, D.K.

    2005-07-01

    Jute fiber composites were prepared with novolac and coal, phenolated-oxidized super clean coal (POS), petroleum vacuum residue (XVR)-modified phenol-formaldehyde (novolac) resin. Five different type of resins, i.e., coal, POS, and XVR-modified resins were used by replacing (10% to 50%) with coal, POS, and XVR. The composites thus prepared have been characterized by tensile strength, hardness, thermogravimetric analysis (TGA), Fourier-transfer infrared (FT-IR), water absorption, steam absorption, and thickness swelling studies. Twenty percent POS-modified novolac composites showed almost the same tensile strength as that of pure novolac composites. After 30% POS incorporation, the tensile strength decreased to 25.84MPa from 33.96MPa in the case of pure novolac resin composites. However, after 50% POS incorporation, the percent retention of tensile strength was appreciable, i.e., 50.80% retention of tensile strength to that of pure novolac jute composites. The tensile strength of coal and XVR-rnodified composites showed a trend similar to that shown by POS-modified novolac resin composites. However, composites prepared from coal and XVR-modified resin with 50% phenol replacement showed 25.4% and 42% tensile strength retention, respectively, compared to that of pure novolac jute composites. It was found that the hardness of the modified composites slightly decreased with an increase in coal, POS, and XVR incorporation in the resin. The XVR-modified composites showed comparatively lower steam absorption than did coal or POS-modified composites. The thermal stability of the POS-modified composites was the highest among the composites studied. The detailed results obtained are being reported.

  18. Novolacs With Alternating P-Cresol & Polyhydroxyphenyl Monomer Units: Developer Cationic Effects And Thermal Properties

    NASA Astrophysics Data System (ADS)

    Blakeney, Andrew J.; Jeffries, Alfred T.; Wehrle, John J.; Gardner, Wesley M.

    1988-01-01

    Novolacs which alternate p-cresol monomer units with polyhydroxyphenyl monomer units have been synthesized by acid catalyzed condensation of 2,6-bis(hydroxymethyl)-p-cresol with polyhydroxybenzenes such as resorcinol or 4-chlororesorcinol. These novolacs are highly alkaline soluble and exhibit improved glass transition temperatures relative to conventional novolacs. Unexpected developer cation effects have been observed on the dissolution times of some of these novolacs. The effect of molecular weight on these effects will be discussed for one system. The dissolution discrimination and inhibition of a 4- chlororesorcinol containing novolac was examined relative to a standard m-,p-cresol novolac and polyvinyl phenol. Images produced from a resist using a p-cresol/ 4-chlororesorcinol novolac showed no significant image degradation at 200 degrees C.

  19. 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.

  20. Heptachlor epoxide

    Integrated Risk Information System (IRIS)

    Heptachlor epoxide ; CASRN 1024 - 57 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogen

  1. 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.

  2. Epoxidation catalyst and process

    DOEpatents

    Linic, Suljo; Christopher, Phillip

    2010-10-26

    Disclosed herein is a catalytic method of converting alkenes to epoxides. This method generally includes reacting alkenes with oxygen in the presence of a specific silver catalyst under conditions suitable to produce a yield of the epoxides. The specific silver catalyst is a silver nanocrystal having a plurality of surface planes, a substantial portion of which is defined by Miller indices of (100). The reaction is performed by charging a suitable reactor with this silver catalyst and then feeding the reactants to the reactor under conditions to carry out the reaction. The reaction may be performed in batch, or as a continuous process that employs a recycle of any unreacted alkenes. The specific silver catalyst has unexpectedly high selectivity for epoxide products. Consequently, this general method (and its various embodiments) will result in extraordinarily high epoxide yields heretofore unattainable.

  3. Succinic anhydrides from epoxides

    SciTech Connect

    Coates, Geoffrey W.; Rowley, John M.

    2013-07-09

    Catalysts and methods for the double carbonylation of epoxides are disclosed. Each epoxide molecule reacts with two molecules of carbon monoxide to produce a succinic anhydride. The reaction is facilitated by catalysts combining a Lewis acidic species with a transition metal carbonyl complex. The double carbonylation is achieved in single process by using reaction conditions under which both carbonylation reactions occur without the necessity of isolating or purifying the product of the first carbonylation.

  4. Succinic anhydrides from epoxides

    SciTech Connect

    Coates, Geoffrey W; Rowley, John M

    2014-12-30

    Catalysts and methods for the double carbonylation of epoxides are disclosed. Each epoxide molecule reacts with two molecules of carbon monoxide to produce a succinic anhydride. The reaction is facilitated by catalysts combining a Lewis acidic species with a transition metal carbonyl complex. The double carbonylation is achieved in single process by using reaction conditions under which both carbonylation reactions occur without the necessity of isolating or purifying the product of the first carbonylation.

  5. Fabrication and physical testing of graphite composite panels utilizing woven graphite fabric with current and advanced state-of-the-art resin systems

    NASA Technical Reports Server (NTRS)

    Lee, S. C. S.

    1979-01-01

    Three weaves were evaluated; a balanced plain weave, a balanced 8-harness satin weave, and a semiunidirectional crowfoot satin weave. The current state-of-the-art resin system selected was Fiberite's 934 Epoxy; the advanced resin systems evaluated were Phenolic, Phenolic/Novolac, Benzyl and Bismaleimide. The panels were fabricated for testing on NASA/Ames Research Center's Composites Modification Program. Room temperature mechanical tests only were performed by Hitco; the results are presented.

  6. Phenolic dyes as nonbleachable absorbers compatible with novolac resins for linewidth control in photoresists

    DOEpatents

    Renschler, C.L.

    1986-11-25

    Photoresist techniques and compositions are provided employing curcumin as an absorptive dye for the purpose of reducing linewidth non-uniformity caused by scattered and reflective light from the substrate-resist interface. The photoresist compositions containing curcumin as the absorptive dye are used in the production of microelectronic circuitry by both single layer and multilayer photoresist techniques.

  7. Characterization of the development of DNQ/novolac resists by surface energy measurements

    NASA Astrophysics Data System (ADS)

    Fadda, Emilienne; Amblard, Gilles R.; Weill, Andre P.; Prola, Alain

    1994-05-01

    The resist processes used for optical lithography are mainly positive tone, based on the use of DNQ/novolac photoresists. It has been demonstrated that enhancing the resist pattern profiles is possible by optimization of the development step. Development techniques, such as two-step or interrupted development, have been introduced to enhance the contrast of DNQ/novolac resists. This paper demonstrates that the resist surface modifications occurring during development can be followed by surface energy measurements. The surface energy changes of four commercial resists (JSR IX 500, Shipley SPRT 510, OCG HPR 504 and Hoechst AZ 5206) during development are investigated. The results are then correlated to the changes in pattern profiles obtained when using the interrupted development technique.

  8. Novel combination of photoactive species: photoresists formed from selectively esterified novolacs and polyfunctional photoactive compounds

    NASA Astrophysics Data System (ADS)

    Jeffries, Alfred T., III; Brzozowy, David J.; Naiini, Ahmad A.; Gallagher-Wetmore, Paula M.

    1997-07-01

    The addition of selected PACs to resists comprised of selectively esterified DNQ novolacs improves their performance in terms of side wall angle and resolution compared to resists whose photoactive component is composed of entirely selectively esterified DNQ novolacs. The performance gain is particularly evident for the resists with two selectively esterified fractions. A conventional 60/40 m-cresol/p-cresol novolac was synthesized and fractionated into five nearly equal weight fractions using supercritical fluids (SCF) fractionation technique. Resists were made from either a single esterified fraction [fraction Two, esterification level (EL), 42%] or dual esterified fractions (fractions Two and Four, EL 21% each), a selection of PACs and the remaining unesterified fractions. They were compared to a control containing only the corresponding esterified fraction(s). The PACs A and B were effective at increasing the resist profile angle for 0.50 (mu) features in the singly esterified novalacs in comparison to the control material and exhibited flat tops. The resolution and profiles of dual esterified fraction resists improved significantly when low levels of PACs were added to dual esterified fraction control resist. The comparison was made from 0.40 (mu) features. The resist made using PAC C is the best candidate for photospeed although its profile angle is less in comparison to PACs A and B.

  9. Friction reducing properties and stability of epoxidized oleochemicals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have studied the properties of epoxidized oleochemical methyl esters including epoxidized soybean oil, epoxidized methyl oleate, epoxidized methyl linoleate, and epoxidized methyl linolenate. We have compared these materials to a similar series of unmodified olefins. Several interesting trends ...

  10. Microbial production of epoxides

    DOEpatents

    Clark, Thomas R.; Roberto, Francisco F.

    2003-06-10

    A method for microbial production of epoxides and other oxygenated products is disclosed. The method uses a biocatalyst of methanotrophic bacteria cultured in a biphasic medium containing a major amount of a non-aqueous polar solvent. Regeneration of reducing equivalents is carried out by using endogenous hydrogenase activity together with supplied hydrogen gas. This method is especially effective with gaseous substrates and cofactors that result in liquid products.

  11. 21 CFR 177.1650 - Polysulfide polymer-polyepoxy resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1650 Polysulfide polymer-polyepoxy resins. Polysulfide polymer... polyfunctional epoxide resins, cured with the aid of tri(dimethylaminomethyl) phenol, to which have been...

  12. 40 CFR 63.1431 - Process vent annual epoxides emission factor plan requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... factor plan requirements. 63.1431 Section 63.1431 Protection of Environment ENVIRONMENTAL PROTECTION... group determination procedures in the NESHAP for Group I Polymers and Resins (40 CFR part 63, subpart U... Production § 63.1431 Process vent annual epoxides emission factor plan requirements. (a) Applicability...

  13. Process for improving moisture resistance of epoxy resins by addition of chromium ions

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; Stoakley, D. M.; St.clair, T. L.; Singh, J. J. (Inventor)

    1985-01-01

    A process for improving the moisture resistance properties of epoxidized TGMDA and DGEBA resin system by chemically incorporating chromium ions is described. The addition of chromium ions is believed to prevent the absorption of water molecules.

  14. Development and characterization of soy-based epoxy resins and pultruded FRP composites

    NASA Astrophysics Data System (ADS)

    Zhu, Jiang

    This dissertation focuses on the development, manufacture and characterization of novel soy-based epoxy FRP composites. Use of alternative epoxy resin systems derived from a renewable resource holds potential for low cost raw materials for the polymer and composite industries. Epoxidized Allyl Soyate (EAS) and Epoxidized Methyl Soyate (EMS) were developed from soybean oil with two chemical modification procedures: transesterification and epoxidation. This research investigates the curing characteristics and thermal and mechanical properties of the neat soyate resin systems. The derived soyate resins have higher reactivity and superior performance compared to commercially available epoxidized soybean oil. An efficient two-step curing method was developed in order to utilize these soyate resins to their full potential. The epoxy co-resin systems with varied soyate resin content were successfully used to fabricate composite material through pultrusion. The pultrusion resin systems with 30 wt% soyate resins yielded improved, or comparable mechanical properties with neat commercial resins. A finite element analysis of the heat transfer and curing process was performed to study the processing characterization on glass/epoxy composite pultrusion. This model can be used to establish baseline process variables and will benefit subsequent optimization. This research demonstrates that soy-based resins, especially EAS, show considerable promise as an epoxy resin supplement for use in polymer and composite structural applications. The new products derived from soybean oil can provide competitive performance, low cost and environmental advantages.

  15. Array of Love-wave sensors based on quartz/Novolac to detect CWA simulants.

    PubMed

    Matatagui, D; Fontecha, J; Fernández, M J; Aleixandre, M; Gràcia, I; Cané, C; Horrillo, M C

    2011-09-15

    An array of Love-wave sensors based on quartz and Novolac has been developed to detect chemical warfare agents (CWAs). These weapons are a risk for human health due to their efficiency and high lethality; therefore an early and clear detection is of enormous importance for the people safety. Love-wave devices realized on quartz as piezoelectric substrate and Novolac as guiding layer have been used to make up an array of six sensors, which have been coated with specific polymers by spin coating. The CWAs are very dangerous and for safety reasons their well known simulants have been used: dimethylmethyl phosphonate (DMMP), dipropyleneglycol methyl ether (DPGME), dimethylmethyl acetamide (DMA), dichloroethane (DCE), dichloromethane (DCM) and dichloropentane (DCP). The array has been exposed to these CWA simulants detecting very low concentrations, such as 25 ppb of DMMP, a simulant of nerve agent sarin. Finally, principal component analysis (PCA) as data pre-processing and discrimination technique, and probabilistic neural networks (PNN) as patterns classification technique have been applied. The performance of the sensor array has shown stability, accuracy, high sensitivity and good selectivity to these simulants. PMID:21807207

  16. Assessment of the chemical changes during storage of phenol-formaldehyde resins pyrolysis gas chromatography mass spectrometry, inverse gas chromatography and Fourier transform infra red methods.

    PubMed

    Strzemiecka, B; Voelkel, A; Zięba-Palus, J; Lachowicz, T

    2014-09-12

    The chemical changes occurring in the phenol-formaldehyde resins (resol and novolac type) during their storage were investigated. In this paper the FT-IR, py-GCMS and inverse gas chromatography methods were applied for assessment of the changes occurring during storage of the phenolic resins. We have found that during storage some examined resins occurred partial curing. The results from all techniques applied are consistent. Py-GCMS is useful technique for screening the storage processes but IGC seems to be most sensitive one. PMID:25092596

  17. A New Class Of Resins For Deep Ultraviolet Photoresists

    NASA Astrophysics Data System (ADS)

    Osuch, C. E.; Brahim, K.; Hopf, F. R.; McFarland, M. J.; Mooring, A.; Wu, C. J.

    1986-07-01

    As Bowden has pointed out in his recent discussion on high resolution lithography, conventional photoresists are not particularly suitable for use in the deep ultraviolet (DUV) regime.' The reasons for this are: (1) the novolac resin is a strong absorber at wavelengths shorter than 300 nm;2 and (2) the products produced upon irradiation of the photoactive compound (PAC) absorb in this region (which prevents the phenomenon known as "photobleaching" from occurring). Of these two difficulties the first appeared, to us, to be the more restrictive. Therefore we chose to investigate alternate resins, more transparent in the DUV region, to substitute for novolac. We initially sought to remain within the realm of the dissolution inhibition mechanism and to utilize conventional PAC's. Although it was possible to prepare resins having improved UV absorbtion characteristics (a maleimidestyrene copolymer will be discussed here) and to formulate positive acting resists from them, we found that the resists were not able to adequately form high resolution images with vertical wall profiles. Examples of this behavior are presented. Because of the apparent inability to obtain satisfactory wall profiles, we abandoned the methods based on the dissolution inhibition mechanism. We then elected to explore the so-called "chemical amplification" approach pioneered by Wilson, Ito, Frechet, and their coworkers. To this end, maleimide styrene copolymer was substituted on the nitrogen atom with the tertbutyloxy carbonyl group. This resin, upon application of heat, reverts to maleimide styrene via a process which is apparently catalyzed in the presence of acid. These observations led us to develop a photoresist based on a mixture of a photoacid and the N-blocked maleimide/styrene resin. Details of the performance of this resist are presented.

  18. Effect of network structure on thermal and mechanical properties of cured epoxy resin containing mesogenic group

    SciTech Connect

    Ochi, M.; Shimizu, Y.; Tsuyuno, N.

    1996-10-01

    Epoxy resin containing biphenol group as a mesogenic group was cured with phenol (PN) and catechol (CN) novolacs. In the CN-cured biphenol type epoxy resin, the glass-rubber transition, almost disappeared and thus the very high elastic modulus was obtained in the high temperature region. It is clear that the micro-Brownian motion of the network chains is highly suppressed in this cured system. On the other hand, the PN-cured resin showed the well-defined glass-rubber transition and thus the low rubbery modulus. In addition, in the former system, the characteristic pattern like a schlieren texture was clearly observed in the polarized optical microphotographs. This shows that the mesogenic group contained in the epoxy molecule is oriented in the system cued with catechol novolac, which has neighboring active hydrogens. The computer simulation based on the molecular mechanics also showed that the orientation of the network chains should occur in the CN-cured biphenol epoxy system. Thus, we conclude that the suppression of the micro-Brownian motion in the CN-cured system is due to the orientation of network chains containing a mesogenic group. Moreover, it has been shown that die mechanical and bonding strength at high temperature is considerably improved by the suppression of the network chain in the CN-cured biphenol resin system.

  19. Electroless copper coating of epoxide plates in an ultrasonic field.

    PubMed

    Touyeras, F; Hihn, J Y; Doche, M L; Roizard, X

    2001-07-01

    This paper reports the study of ultrasonic irradiation effects on electroless copper coating on an epoxide resin. Several parameters were monitored, such as plating rates, practical adhesion and internal stress, versus varying acoustic powers at a constant frequency of 530 kHz. Exposure conditions were characterised by both transmitted power and interfacial mass transfer coefficients. Optimum conditions expressed in irradiation time and power were determined. The use of ultrasound during electroless copper plating affects the plating rates and the deposits properties, particularly the practical adhesion which increases whereas the internal stress decreases. Then, the changes in the coating mechanisms are discussed. PMID:11441612

  20. Occurrence of bisphenols, bisphenol A diglycidyl ethers (BADGEs), and novolac glycidyl ethers (NOGEs) in indoor air from Albany, New York, USA, and its implications for inhalation exposure.

    PubMed

    Xue, Jingchuan; Wan, Yanjian; Kannan, Kurunthachalam

    2016-05-01

    Bisphenols, bisphenol A diglycidyl ethers (BADGEs), and novolac glycidyl ethers (NOGEs) are used in the production of epoxy resins and polycarbonate plastics. Despite the widespread application of these chemicals in household products, studies on their occurrence in indoor air are limited. In this study, 83 indoor air samples were collected in 2014 from various locations in Albany, New York, USA, to determine the concentrations of bisphenols, BADGEs (refer to BADGE and its derivatives), and NOGEs (refer to NOGE and its derivatives) and to calculate inhalation exposure to these compounds. Among eight bisphenols measured, BPA, BPF, and BPS were found in bulk air (i.e., vapor plus particulate phases), at geometric mean (GM) concentrations of 0.43, 0.69 and 0.09 ng m(-3), respectively. Among 11 BADGEs and NOGEs determined, BADGE·2H2O was the predominant compound found in indoor air (detection rate [DR]: 85.5%), at concentrations as high as 6.71 ng m(-3). Estimation of inhalation exposure to these chemicals for various age groups showed that teenagers had the highest exposure doses to BPA, BPF, BPS, and BADGE·2H2O at 5.91, 9.48, 1.24, and 3.84 ng day(-1), respectively. The body weight-normalized estimates of exposure were the highest for infants, with values at 0.24, 0.39, 0.05, and 0.16 ng kg bw(-1) day(-1) for BPA, BPF, BPS, and BADGE·2H2O, respectively. This is the first survey to report inhalation exposure to bisphenols, BADGEs, and NOGEs. PMID:26923236

  1. Industrially relevant epoxy-acrylate hybrid resin photopolymerizations

    NASA Astrophysics Data System (ADS)

    Ajiboye, Gbenga I.

    Photopolymerization of epoxy-acrylate hybrid resins takes advantages of inherent properties present in the free-radical and cationic reactions to reduce oxygen inhibition problems that plague free-radical reactions. Similarly, the combined reaction mechanisms reduce moisture sensitivity of the cationic reactions. Despite the advantages of epoxy-acrylate hybrid resins, problems persist that need to be addressed. For example, low conversion and polymerization rate of the epoxides are a problem, because the fast acrylate conversion prevents the epoxide from reaching high conversion. Controlling phase separation is challenging, since two moieties with different properties are reacting. The physical properties of the polymer will be impacted by the availability of different moieties. High shrinkage stress results from the acrylate moiety, causing buckling and cracking in film and coating applications. The overall goal of this study is to use the fundamental knowledge of epoxy-acrylate hybrid resins to formulate industrially viable polymers. In order to achieve this goal, the study focuses on the following objectives: (I) determine the apparent activation energy of the hybrid monomer METHB, (II) increase epoxide conversion and polymerization rate of hybrid formulations, and (III) control physical properties in epoxy-acrylate hybrid resins. In order to increase the epoxide conversion and rate of polymerization, the sensitivity of epoxides to alcohol is used to facilitate the activated monomer (AM) mechanism and induce a covalent bond between the epoxide and acrylate polymers through the hydroxyl group. It is hypothesized that if the AM mechanism is facilitated, epoxide conversion will increase. As a result, the resins can be tailored to control phase separation and physical properties, and shrinkage stress can be reduced. In pursuit of these objectives, the hybrid monomer METHB was polymerized at temperatures ranging from 30°C to 70°C to obtain apparent activation

  2. Optical properties and indentation hardness of thin-film acrylated epoxidized oil

    NASA Astrophysics Data System (ADS)

    Rahman, Mohammad Syuhaimi Ab.; Shaktur, Khaled Mohamed; Mohammad, Rahmah; Zalikha, Wan Aimi; Nawi, Norwimie; Mohd, Ahmad Faiza

    2012-02-01

    Epoxy acrylate has been widely used as optical resin for applications such as cladding, the core of a waveguide, and other photonic devices. In this study, sustainable resin from edible oil was used as an alternative to epoxy acrylate. Structural features and the transmission of planar thin-film resin from an ultraviolet-visible spectroscopy (UV-VIS) spectrometer were investigated upon UV exposure. It was found that high transmission still persists for all samples with and without an UV absorber for exposed and unexposed samples. The film was found to absorb strongly below 400 nm. A change in the cut-off wavelength was observed upon exposure. Thin-film hardness and its dynamic indentation in the load-unload mode with different test forces were evaluated. Vickers hardness and the elastic modulus were determined for unacrylated epoxidized soybean oil (ESO) and acrylated epoxidized soybean oil (AESO). It was found that the AESO has a higher Vickers hardness and elastic modulus than those of unacrylated thin film. The Vickers hardness and elastic modulus were found to increase as the applied test force increased. The refractive index, thickness, and modes present were characterized from a spin-coated planar thin film. The refractive index in the transverse electric mode (TE) and transverse magnetic mode (TM) were determined and compared for unacrylated and acrylated epoxidized oil.

  3. Toughening mechanism in elastomer-modified epoxy resins, part 2

    NASA Technical Reports Server (NTRS)

    Yee, A. F.; Pearson, R. A.

    1984-01-01

    The role of matrix ductility on the toughenability and toughening mechanism of elastomer-modified DGEBRA epoxies was investigated. Matrix ductility was varied by using epoxide resins of varying epoxide monomer molecular weights. These epoxide resins were cured using 4,4' diaminodiphenyl sulfone (DDS) and, in some cases, modified with 10% HYCAR(r)CTBN 1300X8. Fracture roughness values for the neat epoxies were found to be almost independent on the monomer molecular weight of the epoxide resin used. However, it was found that the fracture toughness of the elastomer-modified epoxies was very dependent upon the epoxide monomer molecular weight. Tensile dilatometry indicated that the toughening mechanism, when present, is similar to the mechanisms found for the piperidine cured epoxies in Part 1. SEM and OM corroborate this finding. Dynamic mechanical studies were conducted to shed light on the toughenability of the epoxies. The time-dependent small strain behavior of these epoxies were separated into their bulk and shear components. The bulk component is related to brittle fracture, whereas the shear component is related to yielding. It can be shown that the rates of shear and bulk strain energy buildup for a given stress are uniquely determined by the values of Poisson's ratio, nu. It was found that nu increases as the monomer molecular weight of the epoxide resin used increases. This increase in nu can be associated with the low temperature beta relaxation. The effect of increasing cross-link density is to shift the beta relaxation to higher temperatures and to decrease the magnitude of the beta relaxation. Thus, increasing cross-link density decreases nu and increases the tendency towards brittle fracture.

  4. Process for improving mechanical properties of epoxy resins by addition of cobalt ions

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St.clair, A. K. (Inventor)

    1984-01-01

    A resin product useful as an adhesive, composite or casting resin is described as well as the process used in its preparation to improve its flexural strength mechanical property characteristics. Improved flexural strength is attained with little or no change in density, thermal stability or moisture resistance by chemically incorporating 1.2% to 10.6% by weight Co(3) ions in an epoxidized resin system.

  5. Rheology Analysis of Thermosetting Resin Candidates for Use in Fuel Compacting

    SciTech Connect

    Trammell, Michael P.

    2012-06-01

    The AGR-1 and AGR-2 overcoating and compacting method utilized a wet mixing process where liquid resin (Hexion Durite SC-1008) was blended with natural and synthetic graphite to produce a graphite/resin matrix for overcoating. The matrix production method specified in the scale-up plan is a co-grinding jet mill process where powdered resin and graphite are fed at the same time into a jet mill. Because of the change in matrix production style, SC-1008 cannot be used in the jet milling process because it is a liquid. Also, attempts to dry out matrix made with SC-1008 for use in the overcoating process at B&W had mixed results. The SC-1008 resin became tacky when dried which caused the matrix to build up inside the overcoater. The scale- up jet milling/mixing and overcoating processes required that a suite of solid or powdered resins be identified. Suitable resins candidates were down selected to two resins, specifically Plenco 14838 and Hexion SD-1708. These resins are referred to as novolac or “two-stage” resins because they require the addition of a curing agent such as hexamethylenetetramine (Hexa) to promote an increased level of cross linking. The overcoating matrix is made of 3 components; natural graphite, synthetic graphite, and resin. The most influential component of the compacting process is the resin component and how it behaves with regards to time, temperature, and pressure. The selected scale-up resins are considered fast curing which means that the increase in molecular weight (curing) occurs over a relatively short period of time, ranging from a few seconds to several minutes depending on the temperature. To find the optimal compacting conditions it is useful to quantify this behavior. In this report, rheology is used to investigate viscosity as a function of time at specific temperatures for the previously mentioned resins.

  6. Epoxy resin

    DOEpatents

    Wilson, Glenn R.; Salyer, Ival O.; Ball, III, George L.

    1976-07-13

    By mixing one part of a prepolymer containing a polyamine partially polymerized with an organic epoxide and subsequently reacted with a fatty acid containing from 8 to 32 carbon atoms, and then reacting this prepolymer mixture with 3 parts of an organic epoxide, a composition was obtained which made a gas frothable, shear-stable, room temperature curing, low density foam. A particularly advantageous prepolymer was prepared using a polyamine selected from the group consisting of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine, partially polymerized with an organic epoxide having an average molecular weight of about 350 and having an epoxide equivalent of 185 to 192, and reacted with 2-10 weight percent linoleic acid. When one part of this prepolymer was reacted with about three parts of epoxy, and frothed by whipping in air or nitrogen an epoxy foam was produced which could be troweled onto surfaces and into corners or crevices, and subsequently cured, at near ambient temperature, to a strong dimensionally stable foam product.

  7. Organocatalyzed enantioselective desymmetrization of aziridines and epoxides

    PubMed Central

    2013-01-01

    Summary Enantioselective desymmetrization of meso-aziridines and meso-epoxides with various nucleophiles by organocatalysis has emerged as a cutting-edge approach in recent years. This review summarizes the origin and recent developments of enantioselective desymmetrization of meso-aziridines and meso-epoxides in the presence of organocatalysts. PMID:24062828

  8. Toluene Monooxygenase-Catalyzed Epoxidation of Alkenes

    PubMed Central

    McClay, Kevin; Fox, Brian G.; Steffan, Robert J.

    2000-01-01

    Several toluene monooxygenase-producing organisms were tested for their ability to oxidize linear alkenes and chloroalkenes three to eight carbons long. Each of the wild-type organisms degraded all of the alkenes that were tested. Epoxides were produced during the oxidation of butene, butadiene, and pentene but not hexene or octadiene. A strain of Escherichia coli expressing the cloned toluene-4-monooxygenase (T4MO) of Pseudomonas mendocina KR1 was able to oxidize butene, butadiene, pentene, and hexene but not octadiene, producing epoxides from all of the substrates that were oxidized. A T4MO-deficient variant of P. mendocina KR1 oxidized alkenes that were five to eight carbons long, but no epoxides were detected, suggesting the presence of multiple alkene-degrading enzymes in this organism. The alkene oxidation rates varied widely (ranging from 0.01 to 0.33 μmol of substrate/min/mg of cell protein) and were specific for each organism-substrate pair. The enantiomeric purity of the epoxide products also varied widely, ranging from 54 to >90% of a single epoxide enantiomer. In the absence of more preferred substrates, such as toluene or alkenes, the epoxides underwent further toluene monooxygenase-catalyzed transformations, forming products that were not identified. PMID:10788354

  9. Process modeling, optimization and analysis of esterification reaction of cashew nut shell liquid (CNSL)-derived epoxy resin using response surface methodology.

    PubMed

    Sultania, Minakshi; Rai, J S P; Srivastava, Deepak

    2011-01-30

    Concept of five-levels-four-factors central composite rotatable design was utilized for the optimization of reaction conditions of cardanol-based vinyl ester resin production, by employing response surfaces methodology, to establish a relationship between the process variables and the extent of conversion under a wide range of operating conditions which resulted in different extent of conversions. The maximum extent of conversion of cardanol-based epoxidised novolac resin (CNE) and methacrylic acid (MA) catalyzed by triphenylphosphine was found to be 95% at optimum set of conditions of molar ratio (1:0.9) between CNE and MA, catalyst concentration (1.49%), reaction temperature (89.96 °C) and reaction time (17,991s). Geometrical representation of the mathematical models in three-dimensional response surface plots and isoresponse contour plots served as a good aid in understanding the behavior of reaction under different operating conditions by only limited sets of experiments. A statistical model predicted that the highest conversion yield of novolac resin would be greater than 95% at the optimized reaction conditions. The predicted values thus obtained were close to the experimental values indicating suitability of the model. PMID:21051142

  10. Variation of Resin Properties Through the Thickness of Cured Samples

    NASA Technical Reports Server (NTRS)

    1984-01-01

    It is the purpose of this work to gain knowledge of the glassy materials used as matrices in composites and to study the homogeneity resulting from the curing process. An attempt is made to link the glass transition quantitatively with the presence of a given material. Expoxy resins containing various amounts of hardener (TGDDM/DDS system) were cured in a muffle furnace at 473 K for seven hours. The glass transition temperature, T sub g versus weight minus percent of hardener in the epoxy resin were measured. A limit was rapidly reached in T sub g at only two percent hardener. Thus, the glass transition of the fully cured epoxy-amine matrix seems not much different from the epoxide-epoxide cure. The T sub g versus cure-time for the epoxide-epoxide reaction was also studied. My 720 was cured by itself in an oil bath at 473 K for different lengths of time. The T sub g was found to increase exponentially with the cure time, and a maximum T sub g of about 450 K was reached after eleven hours. The reaction was found to be inhibited by running the sample under argon.

  11. Quetol 651: Not just a low viscosity resin.

    PubMed

    Ellis, E Ann

    2016-01-01

    Quetol 651, a low viscosity epoxy resin, is miscible with alcohols, acetone, and water. It is versatile and can be used as a single epoxide or mixed with other epoxides and anhydrides. The most important characteristic is that the addition of Quetol 651 to a formulation results in a lower viscosity embedding medium and allows for good detection of antigenic activity. Properly formulated and mixed resins containing Quetol 651 have excellent sectioning properties and good beam stability. The decrease in viscosity lends to lower specific gravity of the embedding medium and less interfering electron density between specimen elements resulting in better spatial resolution. New formulations and viscosity data are presented and compared to long used, embedding formulations and the extensive uses of Quetol 651 are reviewed. PMID:26516031

  12. Kinetic Resolution in Asymmetric Epoxidation using Iminium Salt Catalysis

    PubMed Central

    2013-01-01

    The first reported examples of kinetic resolution in epoxidation reactions using iminium salt catalysis are described, providing up to 99% ee in the epoxidation of racemic cis-chromenes. PMID:23862687

  13. Alkene epoxidation employing metal nitro complexes

    DOEpatents

    Andrews, M.A.; Cheng, C.W.; Kelley, K.P.

    1982-07-15

    Process for converting alkenes to form epoxides utilizes transition metal nitro complexes of the formula: M(RCN)/sub 2/XNO/sub 2/ wherein M is palladium or platinum, R is an alkyl or aryl group containing up to 12 carbon atoms, and X is a monoanionic, monodentate ligand such as chlorine, optionally in the presence of molecular oxygen.

  14. Epoxidation of Methyl Oleate using Heterogeneous Catalyst

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work we studied the catalytic activity of commercial alumina, and laboratory synthesized alumina doped with Lewis acid metals, in the epoxidation of methyl oleate with aqueous hydrogen peroxide. It was observed that the reaction yields increased when the amount of catalyst, the quantity of ...

  15. Determination of equivalent weight of epoxides

    SciTech Connect

    Selig, W.S.

    1987-01-15

    Hydrogen bromide is generated in situ by the addition of perchloric acid to quaternary ammonium bromide. The HBr rapidly opens the oxirane (epoxide) ring. The excess hydrogen bromide is sensed and indicated by the electrode couple in the potentiometric titration. 2 refs.

  16. Epoxidation of methyl oleate using heterogeneous catalyst

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A variety of synthetic processes have been reported, utilizing epoxidized soybean oil and corresponding epoxy fatty ester systems, as intermediates to obtain industrially significant materials, e.g. bio-based polymers, emollients, chemical solvents, fuel additives, and lubricants. One of the reason...

  17. Polymerization of epoxidized triglycerides with fluorosulfonic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of triglycerides as agri-based renewable raw materials for the development of new products is highly desirable in view of uncertain future petroleum prices. A new method of polymerizing epoxidized soybean oil has been devised with the use of fluorosulfonic acid. Depending on the reaction con...

  18. Functionalization of Oleyl Carbonate by Epoxidation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increasing interest in commercial applications due to their physical properties and relatively straightforward synthesis. Herein, oleyl carbonate (1), an olechemical-based compound derived from oleyl alcohol, was epoxidized utilizing performic acid generated in situ from formic acid and 50% H2O2. ...

  19. Sub-micrometer Novolac-Derived Carbon Beads for High Performance Supercapacitors and Redox Electrolyte Energy Storage.

    PubMed

    Krüner, Benjamin; Lee, Juhan; Jäckel, Nicolas; Tolosa, Aura; Presser, Volker

    2016-04-13

    Carbon beads with sub-micrometer diameter were produced with a self-emulsifying novolac-ethanol-water system. A physical activation with CO2 was carried out to create a high microporosity with a specific surface area varying from 771 (DFT) to 2237 m(2)/g (DFT) and a total pore volume from 0.28 to 1.71 cm(3)/g. The carbon particles conserve their spherical shape after the thermal treatments. The controllable porosity of the carbon spheres is attractive for the application in electrochemical double layer capacitors. The electrochemical characterization was carried out in aqueous 1 M Na2SO4 (127 F/g) and organic 1 M tetraethylammonium tetrafluoroborate in propylene carbonate (123 F/g). Furthermore, an aqueous redox electrolyte (6 M KI) was tested with the highly porous carbon and a specific energy of 33 W·h/kg (equivalent to 493 F/g) was obtained. In addition to a high specific capacitance, the carbon beads also provide an excellent rate performance at high current and potential in all tested electrolytes, which leads to a high specific power (>11 kW/kg) with an electrode thickness of ca. 200 μm. PMID:26996252

  20. Curing agent for polyepoxides and epoxy resins and composites cured therewith. [preventing carbon fiber release

    NASA Technical Reports Server (NTRS)

    Serafini, T. T.; Delvigs, P.; Vannucci, R. D. (Inventor)

    1981-01-01

    A curing for a polyepoxide is described which contains a divalent aryl radical such as phenylene a tetravalent aryl radical such as a tetravalent benzene radical. An epoxide is cured by admixture with the curing agent. The cured epoxy product retains the usual properties of cured epoxides and, in addition, has a higher char residue after burning, on the order of 45% by weight. The higher char residue is of value in preventing release to the atmosphere of carbon fibers from carbon fiber-epoxy resin composites in the event of burning of the composite.

  1. Effect of Monomer Structure on Curing Behavior, CO2 Solubility, and Gas Permeability of Ionic Liquid-Based Epoxy-Amine Resins and Ion-Gels

    SciTech Connect

    McDanel, WM; Cowan, MG; Barton, JA; Gin, DL; Noble, RD

    2015-04-29

    New imidazolium- and pyrrolidinium-based bis(epoxide)-functionalized ionic liquid (IL) monorners were synthesized: and reacted with multifunctional amine monomers to produce cross-linked, epoxy-amine poly(ionic liquid) (PIL) resins and PIL/IL ion-gel membranes. The length and chemical nature (i.e., alkyl versus ether) between the irrildazolium group and epokitie groups were studied to determine their effects on CO2 affinity. The CO2 uptake (millimoles per gram) of the epoxy amine resins (between 0.1 and 1 mmol/g) was found to depend predominately on the epoxide-to-amine ratio and the bis(epoxide) IL molecular weight. The effect of using a primary versus a secondary amine-containing multifunctional monoiner was also assessed for the resin-synthesis. Secondary amines can increase CO2 permeability but also increase the iime required for biS(epoxide) coriversion. When either the epoxide or athine monomer structure is changed, the CO2 solubility and permeability of the resulting PIL resins and ion-sel membranes can be tuned.

  2. Stereochemistry of the epoxidation of internal perfluoroalkenes with sodium hypochlorite

    SciTech Connect

    Filyakova, T.I.; Peschanskii, N.V.; Kodess, M.I.; Zapevalov, A.Ya.; Kolenko, I.P.

    1988-07-20

    The authors studied the epoxidation of the mixture of cis and trans isomers of internal disubstituted perfluoroalkenes with sodium hypochlorite. Epoxidation was realized with an alkaline aqueous solution of sodium hypochlorite in the presence of acetonitrile. The epoxidation of the geometric isomers of internal disubstituted perfluoroalkenes by sodium hypochlorite is stereospecific. The /sup 19/F NMR spectra of the cis and trans isomers of internal perfluoroolefin oxides were obtained, and the relationships are discussed.

  3. Epoxide composites with thermally reduced graphite oxide and their properties

    NASA Astrophysics Data System (ADS)

    Arbuzov, A. A.; Muradyan, V. E.; Tarasov, B. P.; Sokolov, E. A.; Babenko, S. D.

    2016-05-01

    The properties of epoxide composites modified by thermal reduced graphite oxide are studied. The dielectric permittivities of epoxide composites with additives of up to 1.5 wt % of reduced graphite oxide are studied at a frequency of 9.8 GHz. It is shown that despite its low electrical conductivity, the large specific surface area of reduced graphite oxide allows us to create epoxide composites with high complex dielectric permittivities and dielectric loss tangents.

  4. Simple Epoxide Formation for the Organic Laboratory Using Oxone

    ERIC Educational Resources Information Center

    Broshears, Williams C.; Esteb, John J.; Richter, Jeremy; Wilson, Anne M.

    2004-01-01

    Epoxide chemistry is widely used in organic synthesis and regularly discussed in organic chemistry textbooks. An experiment to generate dimethyldioxirane in situ from acetone using Oxone is explained.

  5. The electron-impact promoted fragmentation of aurone epoxides.

    NASA Technical Reports Server (NTRS)

    Brady, B. A.; O'Sullivan, W. I.; Duffield, A. M.

    1972-01-01

    The mass spectra of six aurone epoxides have been rationalized with the aid of high resolution mass spectrometry and metastable ion evidence. These compounds fragment in a well defined manner and mechanisms are proposed for the formation of their characteristic ions. Some similarity was observed between the mass spectra of 6-methoxyaurone epoxide (II), 4-hydroxy-7-methoxy-3-phenylcoumarin (VII) and 7-methoxyflavonol (IX). The possibility that VII and IX are intermediates in the fragmentation of epoxide II is discussed. Thermal rearrangement of aurone epoxide II was shown to yield the corresponding flavonol IX and coumarin VII.

  6. Remote cure monitoring of polymeric resins by laser Raman spectroscopy

    SciTech Connect

    Hong, K.C.; Vess, T.M.; Lyon, R.E.; Myrick, M.L.

    1993-05-01

    The validity of using Raman spectroscopy to monitor the cure chemistries of amine-cured epoxy is demonstrated by correlating NIR absorbance measurements with Raman measurements for a concentration series of bisphenol-A diglycidylether in its own reaction product with diethylamine. The intensity of a normalized Raman peak at 1240 cm{sup {minus}l}, assigned to the epoxide functionality, was found to be linearly related to the concentration of epoxide groups in the resin mixtures. Also, it is shown that the Ciba-Geigy Matrimid 5292 system can be monitored by ex-situ FT-Raman spectroscopy by observing changes in the carbonyl stretching (1773 cm{sup {minus}1}) or the C=C stretching of maleimide (1587 cm{sup {minus}1}) during the cure reaction.

  7. Studies on acrylated epoxydised triglyceride resin-co-butyl methacrylate towards the development of biodegradable pressure sensitive adhesives.

    PubMed

    David, S Begila; Sathiyalekshmi, K; Gnana Raj, G Allen

    2009-12-01

    The potential chemical utility of Soya bean oil for the preparation of novel biodegradable polymeric pressure sensitive adhesive has been investigated. Epoxy resin was prepared through in situ epoxidation of Soya bean oil under controlled reaction conditions. Acrylated epoxidised triglyceride resin (AET resin) and copolymer of AET resin with butyl methacrylate were prepared and evaluated. Higher the concentration of butyl methacrylate higher is the degree of copolymerization of AET resin with butyl methacrylate. An optimum concentration of AET resin with butyl methacrylate (100 : 0.40) yields favourable shear holding time and peel strength to qualify as pressure sensitive adhesive. The candidate PSA formulation is biodegradable with antimicrobial activity against gram positive S. aureus ATCC 25923. PMID:18584126

  8. 40 CFR 721.2675 - Perfluoroalkyl epoxide (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Perfluoroalkyl epoxide (generic name). 721.2675 Section 721.2675 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.2675 Perfluoroalkyl epoxide (generic name). (a) Chemical substances and significant new...

  9. 40 CFR 721.2675 - Perfluoroalkyl epoxide (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Perfluoroalkyl epoxide (generic name). 721.2675 Section 721.2675 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.2675 Perfluoroalkyl epoxide (generic name). (a) Chemical substances and significant new...

  10. 40 CFR 721.2675 - Perfluoroalkyl epoxide (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Perfluoroalkyl epoxide (generic name). 721.2675 Section 721.2675 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.2675 Perfluoroalkyl epoxide (generic name). (a) Chemical substances and significant new...

  11. 40 CFR 721.2675 - Perfluoroalkyl epoxide (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Perfluoroalkyl epoxide (generic name). 721.2675 Section 721.2675 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.2675 Perfluoroalkyl epoxide (generic name). (a) Chemical substances and significant new...

  12. 40 CFR 721.2675 - Perfluoroalkyl epoxide (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Perfluoroalkyl epoxide (generic name). 721.2675 Section 721.2675 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.2675 Perfluoroalkyl epoxide (generic name). (a) Chemical substances and significant new...

  13. 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.

  14. Identification of Epoxide-Derived Metabolite(s) of Benzbromarone.

    PubMed

    Wang, Kai; Wang, Hui; Peng, Ying; Zheng, Jiang

    2016-04-01

    Benzbromarone (BBR) is a benzofuran derivative that has been quite useful for the treatment of gout; however, it was withdrawn from European markets in 2003 because of reported serious incidents of drug-induced liver injury. BBR-induced hepatotoxicity has been suggested to be associated with the formation of a quinone intermediate. The present study reported epoxide-derived intermediate(s) of BBR. An N-acetylcysteine (NAC) conjugate derived from epoxide metabolite(s) was detected in both microsomal incubations of BBR and urine samples of mice treated with BBR. The NAC conjugate was identified as 6-NAC BBR. Ketoconazole suppressed the bioactivation of BBR to the epoxide intermediate(s), and the CYP3A subfamily was the primary enzyme responsible for the formation of the epoxide(s). The present study provided new information on metabolic activation of BBR. PMID:26792818

  15. Epoxides--is there a human health problem?

    PubMed Central

    Manson, M M

    1980-01-01

    The purpose of this review is to consider whether epoxides represent a hazard to human health. Possible means of occupational and non-occupational exposure are discussed with reference to the production and uses of industrially important compounds and other epoxides, such as naturally occurring plant and fungal products. In addition to epoxides themselves, unsaturated compounds that may be metabolised in vivo to epoxides are included, since this appears to be a further important means of exposure. The toxicology, in particular carcinogenicity and mutagenicity, is discussed, along with a brief outline of the biochemistry such as metabolism, binding to cell constituents, and DNA repair mechanisms. The question of interactions between different epoxides in vivo is also raised. PMID:7004476

  16. 4D printing smart biomedical scaffolds with novel soybean oil epoxidized acrylate

    PubMed Central

    Miao, Shida; Zhu, Wei; Castro, Nathan J.; Nowicki, Margaret; Zhou, Xuan; Cui, Haitao; Fisher, John P.; Zhang, Lijie Grace

    2016-01-01

    Photocurable, biocompatible liquid resins are highly desired for 3D stereolithography based bioprinting. Here we solidified a novel renewable soybean oil epoxidized acrylate, using a 3D laser printing technique, into smart and highly biocompatible scaffolds capable of supporting growth of multipotent human bone marrow mesenchymal stem cells (hMSCs). Porous scaffolds were readily fabricated by simply adjusting the printer infill density; superficial structures of the polymerized soybean oil epoxidized acrylate were significantly affected by laser frequency and printing speed. Shape memory tests confirmed that the scaffold fixed a temporary shape at −18 °C and fully recovered its original shape at human body temperature (37 °C), which indicated the great potential for 4D printing applications. Cytotoxicity analysis proved that the printed scaffolds had significant higher hMSC adhesion and proliferation than traditional polyethylene glycol diacrylate (PEGDA), and had no statistical difference from poly lactic acid (PLA) and polycaprolactone (PCL). This research is believed to significantly advance the development of biomedical scaffolds with renewable plant oils and advanced 3D fabrication techniques. PMID:27251982

  17. 4D printing smart biomedical scaffolds with novel soybean oil epoxidized acrylate.

    PubMed

    Miao, Shida; Zhu, Wei; Castro, Nathan J; Nowicki, Margaret; Zhou, Xuan; Cui, Haitao; Fisher, John P; Zhang, Lijie Grace

    2016-01-01

    Photocurable, biocompatible liquid resins are highly desired for 3D stereolithography based bioprinting. Here we solidified a novel renewable soybean oil epoxidized acrylate, using a 3D laser printing technique, into smart and highly biocompatible scaffolds capable of supporting growth of multipotent human bone marrow mesenchymal stem cells (hMSCs). Porous scaffolds were readily fabricated by simply adjusting the printer infill density; superficial structures of the polymerized soybean oil epoxidized acrylate were significantly affected by laser frequency and printing speed. Shape memory tests confirmed that the scaffold fixed a temporary shape at -18 °C and fully recovered its original shape at human body temperature (37 °C), which indicated the great potential for 4D printing applications. Cytotoxicity analysis proved that the printed scaffolds had significant higher hMSC adhesion and proliferation than traditional polyethylene glycol diacrylate (PEGDA), and had no statistical difference from poly lactic acid (PLA) and polycaprolactone (PCL). This research is believed to significantly advance the development of biomedical scaffolds with renewable plant oils and advanced 3D fabrication techniques. PMID:27251982

  18. Regiospecific Epoxidation of Carvone: A Discovery-Oriented Experiment for Understanding the Selectivity and Mechanism of Epoxidation Reactions

    ERIC Educational Resources Information Center

    Mak, Kendrew K. W.; Lai, Y. M.; Siu, Yuk-Hong

    2006-01-01

    This article describes a discovery-oriented experiment for demonstrating the selectivity of two epoxidation reactions. Peroxy acids and alkaline H[subscript 2]O[subscript 2] are two commonly used reagents for alkene epoxidation. The former react preferentially with electron-rich alkenes while the latter works better with alpha,beta-unsaturated…

  19. Thermoset coatings from epoxidized sucrose soyate and blocked, bio-based dicarboxylic acids.

    PubMed

    Kovash, Curtiss S; Pavlacky, Erin; Selvakumar, Sermadurai; Sibi, Mukund P; Webster, Dean C

    2014-08-01

    A new 100% bio-based thermosetting coating system was developed from epoxidized sucrose soyate crosslinked with blocked bio-based dicarboxylic acids. A solvent-free, green method was used to block the carboxylic acid groups and render the acids miscible with the epoxy resin. The thermal reversibility of this blocking allowed for the formulation of epoxy-acid thermoset coatings that are 100% bio-based. This was possible due to the volatility of the vinyl ethers under curing conditions. These systems have good adhesion to metal substrates and perform well under chemical and physical stress. Additionally, the hardness of the coating system is dependent on the chain length of the diacid used, making it tunable. PMID:24777954

  20. Bacterial Expression and HTS Assessment of Soluble Epoxide Hydrolase Phosphatase.

    PubMed

    Klingler, Franca-Maria; Wolf, Markus; Wittmann, Sandra; Gribbon, Philip; Proschak, Ewgenij

    2016-08-01

    Soluble epoxide hydrolase (sEH) is a bifunctional enzyme that possesses an epoxide hydrolase and lipid phosphatase activity (sEH-P) at two distinct catalytic domains. While the physiological role of the epoxide hydrolase domain is well understood, the consequences of the phosphatase activity remain unclear. Herein we describe the bacterial expression of the recombinant N-terminal domain of sEH-P and the development of a high-throughput screening protocol using a sensitive and commercially available substrate fluorescein diphosphate. The usability of the assay system was demonstrated and novel inhibitors of sEH-P were identified. PMID:27009944

  1. Purification and specificity of a human microsomal epoxide hydratase

    PubMed Central

    Oesch, Franz

    1974-01-01

    Epoxide hydratase was solubilized from human liver microsomal fractions and purified to an extent where the specific activity was 40-fold greater than that of the liver homogenate. Combination of homogenate and purified preparation showed that the increase in activity was not due to the removal of an inhibitor. Monosubstituted oxiranes with a lipophilic substituent larger than an ethyl group (isopropyl, t-butyl, n-hexyl, phenyl) readily interacted as substrates or inhibitors with this purified human epoxide hydratase, whereas those with a small substituent (methyl, ethyl, vinyl) were inactive, probably reflecting greater affinity of the former epoxides owing to lipophilic binding sites near the active site of the enzyme. In a series of oxiranes having a lipophilic substituent of sufficient size (styrene oxides), monosubstituted as well as 1,1- and cis-1,2-disubstituted oxiranes readily served as substrates or inhibitors of the enzyme, but not the trans-1,2-disubstituted, tri- or tetra-substituted oxiranes. trans-Substitution at the oxirane ring apparently prevents access of the oxirane ring to the active site by steric hindrance. Epoxide hydratase was also solubilized from microsomal fractions of rat and guinea-pig liver and purified by the same procedure. Structural requirements for effective interaction of substrates, inhibitors and activators were qualitatively identical for epoxide hydratase from the three sources. However, several quantitative differences were observed. Thus human hepatic epoxide hydratase seems to be very similar to, although not identical with, the enzyme from guinea pig or rat. Studies with epoxide hydratase from the latter two species therefore appear to be significant with respect to man. In addition, knowledge of structural requirements for epoxides to serve as substrates for human epoxide hydratase may prove useful for drug design. Compounds which need aromatic or olefinic moieties for their desired effect would not be expected to lead

  2. Carcinogenicity and mechanistic insights on the behavior of epoxides and epoxide-forming chemicals.

    PubMed

    Melnick, Ronald L

    2002-12-01

    Many epoxides and their precursors are high production volume chemicals that have major uses in the polymer industry and as intermediates in the manufacture of other chemicals. Several of these chemicals were demonstrated to be carcinogenic in laboratory animal studies conducted by the Ramazzini Foundation (e.g., vinyl chloride, acrylonitrile, styrene, styrene oxide, and benzene) and by the National Toxicology Program (e.g., ethylene oxide, 1,3-butadiene, isoprene, chloroprene, acrylonitrile, glycidol, and benzene). The most common sites of tumor induction were lung, liver, harderian gland, and circulatory system in mice; Zymbal's gland and brain in rats; and mammary gland and forestomach in both species. Differences in cancer outcome among studies of epoxide chemicals may be related to differences in study design (e.g., dose, duration, and route of exposure; observation period; animal strains), as well as biological factors affecting target organ dosimetry of the DNA-reactive epoxide (toxicokinetics) and tissue response (toxicodynamics). N7-Alkylguanine, N1-alkyladenine, and cyclic etheno adducts, as well as K-ras and p53 mutations, have been detected in animals and/or workers exposed to several of these chemicals. The classifications of these chemical carcinogens by IARC and NTP are based on animal and human data and results of mechanistic studies. Reducing occupational and environmental exposures to these chemicals will certainly reduce human cancer risks. PMID:12562636

  3. Quantification of derivatives of bisphenol A diglycidyl ether (BADGE) and novolac glycidyl ether (NOGE) migrated from can coatings into tuna by HPLC/fluorescence and MS detection.

    PubMed

    Berger, U; Oehme, M; Girardin, L

    2001-01-01

    A reversed phase high performance liquid chromatographic method combined with fluorescence and mass spectrometric detection in series is presented for the separation and quantification of bisphenol A diglycidyl ether (BADGE) and novolac glycidyl ether (NOGE) derivatives in extracts from food can coatings, tuna and oil. Fifteen samples of tuna cans bought in four European countries were investigated. Atmospheric pressure chemical ionization mass spectrometry in the positive ion mode (APCI(+)-MS) allowed to tentatively identify BADGE and NOGE related compounds originating from reactions of the glycidyl ethers with bisphenols, phenol, butanol, water and hydrochloric acid. Quantification was based on the external standard method and fluorescence detection. Mass fractions up to 3.7 micrograms/g were found for hydrochlorination products of bisphenol F diglycidyl ether (BFDGE + 2HCl) in tuna. Furthermore, total migration quantities of phenolic ether compounds were estimated. The highest values found were 20 micrograms/g in tuna and 43 micrograms/g in the oil phase. PMID:11225353

  4. Orally Bioavailable Potent Soluble Epoxide Hydrolase Inhibitors

    PubMed Central

    Hwang, Sung Hee; Tsai, Hsing-Ju; Liu, Jun-Yan; Morisseau, Christophe; Hammock, Bruce D.

    2008-01-01

    A series of N,N′-disubstituted ureas having a conformationally restricted cis- or trans-1,4-cyclohexane α to the urea were prepared and tested as soluble epoxide hydrolase (sEH) inhibitors. This series of compounds showed low nanomolar to picomolar activities against recombinant human sEH. Both isomers showed similar potencies, but the trans isomers were more metabolically stable in human hepatic microsomes. Furthermore, these new potent inhibitors show a greater metabolic stability in vivo than previously described sEH inhibitors. We demonstrated that trans-4-[4-(3-adamantan-1-ylureido)cyclohexyloxy]benzoic acid 13g (t-AUCB, IC50 = 1.3 ± 0.05 nM) had excellent oral bioavailability (98%, n = 2) and blood area under the curve in dogs and was effective in vivo to treat hypotension in lipopolysaccharide challenged murine models. PMID:17616115

  5. Potent Urea and Carbamate Inhibitors of Soluble Epoxide Hydrolases

    NASA Astrophysics Data System (ADS)

    Morisseau, Christophe; Goodrow, Marvin H.; Dowdy, Deanna; Zheng, Jiang; Greene, Jessica F.; Sanborn, James R.; Hammock, Bruce D.

    1999-08-01

    The soluble epoxide hydrolase (sEH) plays a significant role in the biosynthesis of inflammation mediators as well as xenobiotic transformations. Herein, we report the discovery of substituted ureas and carbamates as potent inhibitors of sEH. Some of these selective, competitive tightbinding inhibitors with nanomolar Ki values interacted stoichiometrically with the homogenous recombinant murine and human sEHs. These inhibitors enhance cytotoxicity of trans-stilbene oxide, which is active as the epoxide, but reduce cytotoxicity of leukotoxin, which is activated by epoxide hydrolase to its toxic diol. They also reduce toxicity of leukotoxin in vivo in mice and prevent symptoms suggestive of acute respiratory distress syndrome. These potent inhibitors may be valuable tools for testing hypotheses of involvement of diol and epoxide lipids in chemical mediation in vitro or in vivo systems.

  6. Molecular Epoxidation Reactions Catalyzed by Rhenium, Molybdenum, and Iron Complexes.

    PubMed

    Kück, Jens W; Reich, Robert M; Kühn, Fritz E

    2016-02-01

    Epoxidations are of high relevance in many organic syntheses, both in industry and academia. In this personal account, the development of rhenium, molybdenum, and iron complexes in molecular epoxidation catalysis is presented. Methyltrioxorhenium (MTO) is the benchmark catalyst for these reactions, with a thoroughly investigated mechanism and reactivity profile. More recently, highly active molecular molybdenum and iron catalysts have emerged, challenging the extraordinary role of MTO in epoxidation catalysis with high turnover frequencies (TOFs). This development is highlighted in its use of cheaper, more readily available metals, and the challenges of using base metals in catalysis are discussed. These results show the promise that relatively cheap and abundant metals, such as molybdenum and iron, hold for the future of epoxidation catalysis. PMID:26776087

  7. Investigation of copper(II) tetrafluoroborate catalysed epoxide opening

    PubMed Central

    Capes, Amy S.; Crossman, Arthur T.; Webster, Lauren A.; Ferguson, Michael A.J.; Gilbert, Ian H.

    2011-01-01

    We report the extension of the copper(II) tetrafluoroborate catalysed opening of epoxides with alcohols to include a wider variety of alcohols, a range of solvents and a method to purify the products from the reaction. PMID:22505782

  8. Organocatalytic asymmetric epoxidation and tandem epoxidation/Passerini reaction under eco-friendly reaction conditions.

    PubMed

    Deobald, Anna Maria; Corrêa, Arlene G; Rivera, Daniel G; Paixão, Márcio Weber

    2012-10-14

    An eco-friendly synthesis of highly functionalized epoxides and their incorporation into an organocatalytic multicomponent approach are reported. For this, a modified class of diarylprolinol silyl ethers was designed to enable high catalytic activity in an environmentally benign solvent system. The one-pot procedure showed great efficiency in promoting stereoselective multicomponent transformations in a tandem, 'green' fashion. Because of its non-residual, efficient and selective character, this synthetic design shows promise for large-scale applications in both diversity and target-oriented syntheses. PMID:22918441

  9. Cure reaction of epoxy resins catalyzed by graphite-based nanofiller

    NASA Astrophysics Data System (ADS)

    Corcione, C. Esposito; Acocella, Maria Rosaria; Giuri, Antonella; Maffezzoli, Alfonso; Guerra, Gaetano

    2015-12-01

    A significant effort was directed to the synthesis of graphene stacks/epoxy nanocomposites and to the analysis of the effect of a graphene precursor on cure reaction of a model epoxy matrix. A comparative thermal analysis of epoxy resins filled with an exfoliated graphite oxide eGO were conducted. The main aim was to understand the molecular origin of the influence of eGO on the Tg of epoxy resins. The higher Tg values previously observed for low curing temperatures, for epoxy resins with graphite-based nanofillers, were easily rationalized by a catalytic activity of graphitic layers on the reaction between the epoxy and amine groups of the resin, which leads to higher crosslinking density in milder conditions. A kinetic analysis of the cure mechanism of the epoxy resin associated to the catalytical activity of the graphite based filler was performed by isothermal DSC measurements. The DSC results showed that the addition of graphite based filler greatly increased the enthalpy of epoxy reaction and the reaction rate, confirming the presence of a catalytic activity of graphitic layers on the crosslinking reaction between the epoxy resin components (epoxide oligomer and di-amine). A kinetic modelling analysis, arising from an auto-catalyzed reaction mechanism, was finally applied to isothermal DSC data, in order to predict the cure mechanism of the epoxy resin in presence of the graphite based nanofiller.

  10. Photopolymerizations of multicomponent epoxide and acrylate/epoxide hybrid systems for controlled kinetics and enhanced material properties

    NASA Astrophysics Data System (ADS)

    Eom, Ho Seop

    2011-12-01

    Cationic photopolymerization of multifunctional epoxides is very useful for efficient cure at room temperature and has been widely used in coatings and adhesives. Despite excellent properties of the final cured polymers, cationic photopolymerizations of epoxides have seen limited application due to slow reactions (relative to acrylates) and brittleness associated with a highly crosslinked, rigid network. To address these issues, two reaction systems were studied in this thesis: photoinitiated cationic copolymerizations of a cycloaliphatic diepoxide with epoxidized elastomers and acrylate/epoxide hybrid photopolymerizations. Oligomer/monomer structures, viscosity, compositions, and photoinitiator system were hypothesized to play important roles in controlling photopolymerizations of the epoxide-based mixtures. A fundamental understanding of the interplay between these variables for the chosen systems will provide comprehensive guidelines for the future development of photopolymerization systems comparable to the epoxide-based mixtures in this research. For diepoxide/oligomer mixtures, the observed overall enhancement in polymerization rate and ultimate conversion of the cycloaliphatic diepoxide was attributed to the activated monomer mechanism associated with hydroxyl terminal groups in the epoxidized oligomers. This enhancement increased with increasing oligomer content. The mixture viscosity influenced the initial reactivity of the diepoxide for oligomer content above 50 wt.%. Real-time consumption of internal epoxides in the oligomers was successfully determined using Raman spectroscopy. Initial reactivity and ultimate conversion of the internal epoxides decreased with increasing the diepoxide content. This trend was more pronounced for the oligomer containing low internal epoxide content. These results indicate that the reactivity of the hydroxyl groups is higher toward cationic active centers of the diepoxide than those of the internal epoxides in the oligomers

  11. 40 CFR 721.10210 - Soybean oil, epoxidized, reaction products with diethanolamine.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.10210 Soybean oil, epoxidized, reaction products... chemical substance identified as soybean oil, epoxidized, reaction products with diethanolamine (PMN P-09... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Soybean oil, epoxidized,...

  12. 40 CFR 721.10210 - Soybean oil, epoxidized, reaction products with diethanolamine.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.10210 Soybean oil, epoxidized, reaction products... chemical substance identified as soybean oil, epoxidized, reaction products with diethanolamine (PMN P-09... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Soybean oil, epoxidized,...

  13. 40 CFR 721.10210 - Soybean oil, epoxidized, reaction products with diethanolamine.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.10210 Soybean oil, epoxidized, reaction products... chemical substance identified as soybean oil, epoxidized, reaction products with diethanolamine (PMN P-09... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Soybean oil, epoxidized,...

  14. 40 CFR 721.10210 - Soybean oil, epoxidized, reaction products with diethanolamine.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.10210 Soybean oil, epoxidized, reaction products... chemical substance identified as soybean oil, epoxidized, reaction products with diethanolamine (PMN P-09... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Soybean oil, epoxidized,...

  15. Formation of furan fatty alkyl esters from their bis-epoxide fatty esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Epoxidation of vegetable oils and consecutive epoxide ring-opening reaction is a widely investigated path for producing biobased lubricants and polymers. The reaction mechanism and products are considered well-studied and known. In the current study, the reactions of epoxidized alkyl soyate with fou...

  16. Sulfuric acid as a catalyst for ring-opening of biobased bis-epoxides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetable oils can be relatively and easily transformed into bio-based epoxides. Because of this, the acid-catalyzed epoxide ring-opening has been explored for the preparation of bio-based lubricants and polymers. Detailed model studies are carried out only with mono-epoxide made from methyl oleate,...

  17. Soluble epoxide hydrolase: Gene structure, expression and deletion

    PubMed Central

    Harris, Todd R.; Hammock, Bruce D.

    2013-01-01

    Mammalian soluble epoxide hydrolase (sEH) converts epoxides to their corresponding diols through the addition of a water molecule. sEH readily hydrolyzes lipid signaling molecules, including the epoxyeicosatrienoic acids (EETs), epoxidized lipids produced from arachidonic acid by the action of cytochrome p450s. Through its metabolism of the EETs and other lipid mediators, sEH contributes to the regulation of vascular tone, nociception, angiogenesis and the inflammatory response. Because of its central physiological role in disease states such as cardiac hypertrophy, diabetes, hypertension, and pain sEH is being investigated as a therapeutic target. This review begins with a brief introduction to sEH protein structure and function. sEH evolution and gene structure are then discussed before human small nucleotide polymorphisms and mammalian gene expression are described in the context of several disease models. The review ends with an overview of studies that have employed the sEH knockout mouse model. PMID:23701967

  18. Epoxide Chemistry: Guided Inquiry Experiment Emphasizing Structure Determination and Mechanism

    NASA Astrophysics Data System (ADS)

    Krishnamurty, H. G.; Jain, Niveta; Samby, Kiran

    2000-04-01

    This paper presents an operationally simple three-step synthesis of an a-hydroxy acid based on epoxide chemistry. The focus of the experiment is on the preparation of the chalcone epoxide and its reaction with hot alcoholic alkali. The experiment leads to an unpredicted reaction product. Its structure is established as 2-benzyl-2-phenylglycollic acid by chemical and spectroscopic analysis. The hydroxyacid is a good example to bring home an important NMR principle: the nonequivalence of hydrogens adjacent to a stereogenic center. The formation of the alpha-hydroxy acid is a mechanistic puzzle. A stepwise mechanism can be developed applying lecture-based organic chemistry concepts. On the other hand, acid-catalyzed (H2SO4, BF3) reaction of the chalcone epoxide gives benzoylphenylacetaldehyde. The exercise can be used as a multistep organic chemistry experiment. It also gives students a research-type experience.

  19. Epoxidation of propylene dimers and isomerization of mixtures obtained

    SciTech Connect

    Dobrev, D.M.; Kurtev, K.S.

    1988-05-10

    Mixtures of hexenes are obtained in the dimerization of propylene on a Ziegler catalyst. By the epoxidation of this mixture by organic peroxides, followed by isomerization of the oxides, C/sub 6/ ketones, which are used as solvents, can be obtained. The hexenes were obtained by dimerization of propylene in the presence of a Ni(C/sub 5/H/sub 7/O/sub 2/)/sub 2/-P(C/sub 6/H/sub 5/)/sub 3/-(C/sub 3/H/sub 5/)/sub 2/AlCl catalytic system. The epoxidation was carried with technical grade isopropylbenzyl hydroperoxide (IPBHP). MoO/sub 2/(C/sub 5/H/sub 7/O/sub 2/)/sub 2/ was used as the catalyst. The relative rates of epoxidation of different isomers contained in the dimeric fraction, with respect to 2-methyl-1-pentene, was determined by means of competing reactions.

  20. 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.

  1. 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)

  2. The oxidation of copper catalysts during ethylene epoxidation.

    PubMed

    Greiner, M T; Jones, T E; Johnson, B E; Rocha, T C R; Wang, Z J; Armbrüster, M; Willinger, M; Knop-Gericke, A; Schlögl, R

    2015-10-14

    The oxidation of copper catalysts during ethylene epoxidation was characterized using in situ photoemission spectroscopy and electron microscopy. Gas chromatography, proton-transfer reaction mass spectrometry and electron-ionization mass spectrometry were used to characterize the catalytic properties of the oxidized copper. We find that copper corrodes during epoxidation in a 1 : 1 mixture of oxygen and ethylene. The catalyst corrosion passes through several stages, beginning with the formation of an O-terminated surface, followed by the formation of Cu2O scale and eventually a CuO scale. The oxidized catalyst exhibits measurable activity for ethylene epoxidation, but with a low selectivity of <3%. Tests on pure Cu2O and CuO powders confirm that the oxides intrinsically exhibit partial-oxidation activity. Cu2O was found to form acetaldehyde and ethylene epoxide in roughly equal amounts (1.0% and 1.2% respectively), while CuO was found to form much less ethyl aldehyde than ethylene epoxide (0.1% and 1.0%, respectively). Metallic copper catalysts were examined in extreme dilute-O2 epoxidation conditions to try and keep the catalyst from oxidizing during the reaction. It was found that in feed of 1 part O2 to 2500 parts C2H4 (PO2 = 1.2 × 10(-4) mbar) the copper surface becomes O-terminated. The O-terminated surface was found to exhibit partial-oxidation selectivity similar to that of Cu2O. With increasing O2 concentration (>8/2500) Cu2O forms and eventually covers the surface. PMID:26345450

  3. 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.

  4. Ionic Liquid Epoxy Resin Monomers

    NASA Technical Reports Server (NTRS)

    Paley, Mark S. (Inventor)

    2013-01-01

    Ionic liquid epoxide monomers capable of reacting with cross-linking agents to form polymers with high tensile and adhesive strengths. Ionic liquid epoxide monomers comprising at least one bis(glycidyl) N-substituted nitrogen heterocyclic cation are made from nitrogen heterocycles corresponding to the bis(glycidyl) N-substituted nitrogen heterocyclic cations by a method involving a non-nucleophilic anion, an alkali metal cation, epichlorohydrin, and a strong base.

  5. 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

  6. 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.

  7. DEVELOPMENT OF METABOLICALLY STABLE INHIBITORS OF MAMMALIAN MICROSOMAL EPOXIDE HYDROLASE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The microsomal epoxide hydrolase (mEH) plays a significant role in the metabolism of xenobiotics such as polyaromatic toxicants. Additionally, polymorphism studies have underlined a potential role of this enzyme in relation to a number of diseases, such as emphysema, spontaneous abortion, eclampsia ...

  8. Peptidyl-urea based inhibitors of soluble epoxide hydrolases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We prepared a series of amino acid derived cyclohexyl and adamantyl ureas and tested them as inhibitors of the human soluble epoxide hydrolase, and obtained very potent compounds (K(I)=15nM) that are >10-fold more soluble than previously described sEH inhibitors. While our lead compound 2 showed low...

  9. Ring-opening Polymerization of Epoxidized Soybean Oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ring opening polymerization of epoxidized soybean oil (ESO) initiated by boron trifluoride diethyl etherate, (BF3•OEt2), in methylene chloride was conducted in an effort to develop useful biodegradable polymers. The resulting polymers (PESO) were characterized using Infrared (IR), differential scan...

  10. Stability and friction reducing properties of epoxidized oleochemical methyl esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of oleochemicals as biobased replacements for petrochemical lubricants is an important area of study. Physical properties of the epoxidized fatty esters derived from vegetable oil are reported and compared to their olefinic counterparts. Overall the frictional behavior of epoxy methyl olea...

  11. ULTRASOUND-ASSISTED ORGANIC SYNTHESIS: ALCOHOL OXIDATION AND OLEFIN EPOXIDATION

    EPA Science Inventory

    Ultrasound-assisted Organic Synthesis: Alcohol Oxidation and Olefin Epoxidation

    Unnikrishnan R Pillai, Endalkachew Sahle-Demessie , Vasudevan Namboodiri, Quiming Zhao, Juluis Enriquez
    U.S. EPA , 26 W. Martin Luther King Dr. , Cincinnati, OH 45268
    Phone: 513-569-773...

  12. 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.

  13. Effect of epoxidation level on thermal properties and ionic conductivity of epoxidized natural rubber solid polymer nanocomposite electrolytes

    NASA Astrophysics Data System (ADS)

    Harun, Fatin; Chan, Chin Han; Sim, Lai Har; Winie, Tan; Zainal, Nurul Fatahah Asyqin

    2015-08-01

    Effect of epoxide content on the thermal and conductivity properties of epoxidized natural rubber (ENR) solid polymer nanocomposite electrolytes was investigated. Commercial available epoxidized natural rubber having 25 (ENR25) and 50 mole% (ENR50) epoxide, respectively were incorporated with lithium perchlorate (LiClO4) salt and titanium dioxide (TiO2) nanofiller via solution casting method. The solid polymer nanocomposite electrolytes were characterized by differential scanning calorimetry (DSC) and impedance spectroscopy (IS) for their thermal properties and conductivity, respectively. It was evident that introduction of LiClO4 causes a greater increase in glass transition temperature (Tg) and ionic conductivity of ENR50 as compared to ENR25. Upon addition of TiO2 in ENR/LiClO4 system, a remarkable Tg elevation was observed for both ENRs where ENR50 reveals a more pronounced changes. It is interesting to note that they exhibit different phenomenon in ionic conductivity with TiO2 loading where ENR25 shows enhancement of conductivity while ENR50 shows declination.

  14. Effect of epoxidation level on thermal properties and ionic conductivity of epoxidized natural rubber solid polymer nanocomposite electrolytes

    SciTech Connect

    Harun, Fatin; Chan, Chin Han; Winie, Tan; Sim, Lai Har; Zainal, Nurul Fatahah Asyqin

    2015-08-28

    Effect of epoxide content on the thermal and conductivity properties of epoxidized natural rubber (ENR) solid polymer nanocomposite electrolytes was investigated. Commercial available epoxidized natural rubber having 25 (ENR25) and 50 mole% (ENR50) epoxide, respectively were incorporated with lithium perchlorate (LiClO{sub 4}) salt and titanium dioxide (TiO{sub 2}) nanofiller via solution casting method. The solid polymer nanocomposite electrolytes were characterized by differential scanning calorimetry (DSC) and impedance spectroscopy (IS) for their thermal properties and conductivity, respectively. It was evident that introduction of LiClO{sub 4} causes a greater increase in glass transition temperature (T{sub g}) and ionic conductivity of ENR50 as compared to ENR25. Upon addition of TiO{sub 2} in ENR/LiClO{sub 4} system, a remarkable T{sub g} elevation was observed for both ENRs where ENR50 reveals a more pronounced changes. It is interesting to note that they exhibit different phenomenon in ionic conductivity with TiO{sub 2} loading where ENR25 shows enhancement of conductivity while ENR50 shows declination.

  15. 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.

  16. Modeling Epoxidation of Drug-like Molecules with a Deep Machine Learning Network.

    PubMed

    Hughes, Tyler B; Miller, Grover P; Swamidass, S Joshua

    2015-07-22

    Drug toxicity is frequently caused by electrophilic reactive metabolites that covalently bind to proteins. Epoxides comprise a large class of three-membered cyclic ethers. These molecules are electrophilic and typically highly reactive due to ring tension and polarized carbon-oxygen bonds. Epoxides are metabolites often formed by cytochromes P450 acting on aromatic or double bonds. The specific location on a molecule that undergoes epoxidation is its site of epoxidation (SOE). Identifying a molecule's SOE can aid in interpreting adverse events related to reactive metabolites and direct modification to prevent epoxidation for safer drugs. This study utilized a database of 702 epoxidation reactions to build a model that accurately predicted sites of epoxidation. The foundation for this model was an algorithm originally designed to model sites of cytochromes P450 metabolism (called XenoSite) that was recently applied to model the intrinsic reactivity of diverse molecules with glutathione. This modeling algorithm systematically and quantitatively summarizes the knowledge from hundreds of epoxidation reactions with a deep convolution network. This network makes predictions at both an atom and molecule level. The final epoxidation model constructed with this approach identified SOEs with 94.9% area under the curve (AUC) performance and separated epoxidized and non-epoxidized molecules with 79.3% AUC. Moreover, within epoxidized molecules, the model separated aromatic or double bond SOEs from all other aromatic or double bonds with AUCs of 92.5% and 95.1%, respectively. Finally, the model separated SOEs from sites of sp(2) hydroxylation with 83.2% AUC. Our model is the first of its kind and may be useful for the development of safer drugs. The epoxidation model is available at http://swami.wustl.edu/xenosite. PMID:27162970

  17. Modeling Epoxidation of Drug-like Molecules with a Deep Machine Learning Network

    PubMed Central

    2015-01-01

    Drug toxicity is frequently caused by electrophilic reactive metabolites that covalently bind to proteins. Epoxides comprise a large class of three-membered cyclic ethers. These molecules are electrophilic and typically highly reactive due to ring tension and polarized carbon–oxygen bonds. Epoxides are metabolites often formed by cytochromes P450 acting on aromatic or double bonds. The specific location on a molecule that undergoes epoxidation is its site of epoxidation (SOE). Identifying a molecule’s SOE can aid in interpreting adverse events related to reactive metabolites and direct modification to prevent epoxidation for safer drugs. This study utilized a database of 702 epoxidation reactions to build a model that accurately predicted sites of epoxidation. The foundation for this model was an algorithm originally designed to model sites of cytochromes P450 metabolism (called XenoSite) that was recently applied to model the intrinsic reactivity of diverse molecules with glutathione. This modeling algorithm systematically and quantitatively summarizes the knowledge from hundreds of epoxidation reactions with a deep convolution network. This network makes predictions at both an atom and molecule level. The final epoxidation model constructed with this approach identified SOEs with 94.9% area under the curve (AUC) performance and separated epoxidized and non-epoxidized molecules with 79.3% AUC. Moreover, within epoxidized molecules, the model separated aromatic or double bond SOEs from all other aromatic or double bonds with AUCs of 92.5% and 95.1%, respectively. Finally, the model separated SOEs from sites of sp2 hydroxylation with 83.2% AUC. Our model is the first of its kind and may be useful for the development of safer drugs. The epoxidation model is available at http://swami.wustl.edu/xenosite. PMID:27162970

  18. 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.

  19. A definition of the parameters that influence and control the flow of resin during vacuum impregnation of magnets and other structures

    NASA Astrophysics Data System (ADS)

    Canfer, S. J.; Evans, D.; Greenhalgh, R. J. S.; Morrow, D.

    2002-05-01

    After winding and termination, the final stage in the preparation of many superconducting and conventional magnets is vacuum impregnation with an epoxide resin. Given the importance of the vacuum impregnation process in the overall scheme of magnet manufacture, it is surprising that there are many factors that effect the success and economics of the process that are still not quantified. This paper defines the pressure range, outgassing rates and moisture content that are considered necessary to achieve complete resin impregnation of tightly wound or other compacted, high impedance structures.

  20. Direct epoxidation of propylene over stabilized Cu(+) surface sites on titanium-modified Cu2O.

    PubMed

    Yang, Xiaofang; Kattel, Shyam; Xiong, Ke; Mudiyanselage, Kumudu; Rykov, Sergei; Senanayake, Sanjaya D; Rodriguez, José A; Liu, Ping; Stacchiola, Dario J; Chen, Jingguang G

    2015-10-01

    Direct propylene epoxidation by O2 is a challenging reaction because of the strong tendency for complete combustion. Results from the current study demonstrate that by generating highly dispersed and stabilized Cu(+) active sites in a TiCuOx mixed oxide the epoxidation selectivity can be tuned. The TiCuOx surface anchors the key surface intermediate, an oxametallacycle, leading to higher selectivity for epoxidation of propylene. PMID:26215635

  1. Markedly Elevated Carbamazepine-10,11-epoxide/Carbamazepine Ratio in a Fatal Carbamazepine Ingestion

    PubMed Central

    Russell, Jason L.; Spiller, Henry A.; Baker, Daniel D.

    2015-01-01

    Carbamazepine is a widely used anticonvulsant. Its metabolite, carbamazepine-10,11-epoxide, has been found to display similar anticonvulsant and neurotoxic properties. While the ratio of parent to metabolite concentration varies significantly, at therapeutic doses the epoxide concentration is generally about 20% of the parent. We report a case of fatal carbamazepine overdose in which the epoxide metabolite concentration was found to be 450% higher than the parent compound, suggesting a potential role for metabolite quantification in severe toxicity. PMID:26550016

  2. Direct Epoxidation of Propylene over Stabilized Cu+ Surface Sites on Ti Modified Cu2O

    DOE PAGESBeta

    Yang, X.; Kattel, S.; Xiong, K.; Mudiyanselage, K.; Rykov, S.; Senanayake, S. D.; Rodriguez, J. A.; Liu, P.; Stacchiola, D. J.; Chen, J. G.

    2015-07-17

    Direct propylene epoxidation by O2 is a challenging reaction because of the strong tendency for complete combustion. Results from the current study demonstrate the feasibility to tune the epoxidation selectivity by generating highly dispersed and stabilized Cu+ active sites in a TiCuOx mixed oxide. The TiCuOx surface anchors the key surface intermediate, oxametallacycle, leading to higher selectivity for epoxidation of propylene.

  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. 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.

  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. Isolation and characterization of Xenopus soluble epoxide hydrolase.

    PubMed

    Purba, Endang R; Oguro, Ami; Imaoka, Susumu

    2014-07-01

    Soluble epoxide hydrolase (sEH) contributes to cell growth, but the contribution of sEH to embryonic development is not well understood. In this study, Xenopus sEH cDNA was isolated from embryos of Xenopus laevis. The Xenopus sEH was expressed in Escherichia coli and was purified. The epoxide hydrolase and phosphatase activities of purified sEH were investigated. The Xenopus sEH did not show phosphatase activity toward 4-methylumbelliferyl phosphate or several lysophosphatidic acids although it had EH activity. The amino acid sequence of Xenopus sEH was compared with that reported previously. We found amino acid substitutions of the 29th Thr to Asn and the 146th Arg to His and prepared a sEH mutant (N29T/H146R), designed as mutant 1. Neither wild-type sEH nor mutant 1 had phosphatase activity. Additional substitution of the 11th Gly with Asp was found by comparison with human sEH which has phosphatase activity, but the Xenopus sEH mutant G11D prepared as mutant 2 did not have phosphatase activity. The epoxide hydrolase activity of sEH seemed to be similar to that of human sEH, while Xenopus sEH did not have phosphatase activity toward several substrates that human sEH metabolizes. PMID:24681163

  7. Acid-Catalyzed Reaction of Epoxides on Atmospheric Nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, W.; Gomez-Hernandez, M.; Lal, V.; Qiu, C.; Khalizov, A. F.; Wang, L.; Zhang, R.

    2013-12-01

    Aerosol plays an important role in affecting the earth climate and harming human health. Atmospheric aerosols can be formed from either primary emissions or gas-to-particle conversion process. Numerous studies, including both experimental and theoretical, have been carried out to elucidate the mechanism of gas-to-particle conversion process (a.k.a. nucleation) and the later growth stage of newly formed nanoparticles. However, a complete list of species involving in the nucleation and growth processes of nanoparticles is still poorly understood. The growth of newly formed sulfuric acid - water nanoparticles has been suggested to involve several potential organic vapors, such as amines, glyoxal, 2-4 hexadienal, and epoxides. In the present study, new formed sulfuric acid -water nanoparticles were size selected by a differential mobility analyzer and exposed to epoxide vapors. The size-change after exposure was detected using the second differential mobility analyzer. The size-enlarged particles were then collected by an electrostatic precipitator, thermal vaporized, and analyzed by an ion drift chemical ionization mass spectrometer. Our results show that the sizes of nanoparticles are increased considerably and the magnitude of the increment in size is size-dependent. Mass spectrometry analysis of the nanoparticles after exposure demonstrates that low volatile organosulfate and oligomers are formed in nanoparticles upon their exposure to epoxide vapors.

  8. 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.

  9. 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.

  10. 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.

  11. Towards a General Understanding of Carbonyl-Stabilised Ammonium Ylide-Mediated Epoxidation Reactions.

    PubMed

    Novacek, Johanna; Roiser, Lukas; Zielke, Katharina; Robiette, Raphaël; Waser, Mario

    2016-08-01

    The key factors for carbonyl-stabilised ammonium ylide-mediated epoxidation reactions were systematically investigated by experimental and computational means and the hereby obtained energy profiles provide explanations for the observed experimental results. In addition, we were able to identify the first tertiary amine-based chiral auxiliary that allows for high enantioselectivities and high yields for such epoxidation reactions. PMID:27381752

  12. Asymmetric Epoxidation: A Twinned Laboratory and Molecular Modeling Experiment for Upper-Level Organic Chemistry Students

    ERIC Educational Resources Information Center

    Hii, King Kuok; Rzepa, Henry S.; Smith, Edward H.

    2015-01-01

    The coupling of a student experiment involving the preparation and use of a catalyst for the asymmetric epoxidation of an alkene with computational simulations of various properties of the resulting epoxide is set out in the form of a software toolbox from which students select appropriate components. At the core of these are the computational…

  13. 40 CFR 721.7210 - Epoxidized copolymer of phenol and substituted phenol.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Epoxidized copolymer of phenol and substituted phenol. 721.7210 Section 721.7210 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.7210 Epoxidized copolymer of phenol and substituted phenol. (a)...

  14. 40 CFR 721.7210 - Epoxidized copolymer of phenol and substituted phenol.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Epoxidized copolymer of phenol and substituted phenol. 721.7210 Section 721.7210 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.7210 Epoxidized copolymer of phenol and substituted phenol. (a)...

  15. 40 CFR 721.7210 - Epoxidized copolymer of phenol and substituted phenol.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Epoxidized copolymer of phenol and substituted phenol. 721.7210 Section 721.7210 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.7210 Epoxidized copolymer of phenol and substituted phenol. (a)...

  16. 40 CFR 721.7210 - Epoxidized copolymer of phenol and substituted phenol.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Epoxidized copolymer of phenol and substituted phenol. 721.7210 Section 721.7210 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.7210 Epoxidized copolymer of phenol and substituted phenol. (a)...

  17. 40 CFR 721.7210 - Epoxidized copolymer of phenol and substituted phenol.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Epoxidized copolymer of phenol and substituted phenol. 721.7210 Section 721.7210 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.7210 Epoxidized copolymer of phenol and substituted phenol. (a)...

  18. COMPARATIVE STUDIES OF THE EFFECT OF POLYCYCLIC AROMATIC HYDROCARBON GEOMETRY ON THE HYDROLYSIS OF DIOL EPOXIDES

    EPA Science Inventory

    Comparative studies of the effect of polycyclic aromatic hydrocarbon geometry on the hydrolysis of diol epoxides

    The interaction of the diol epoxides (DEs) of both planar and non-planar PAHs with water have been examined using quantum mechanical and molecular dynamics. Th...

  19. General, Highly Selective Synthesis of 1,3- and 1,4-Difunctionalized Building Blocks by Regiodivergent Epoxide Opening.

    PubMed

    Funken, Nico; Mühlhaus, Felix; Gansäuer, Andreas

    2016-09-19

    We describe a regiodivergent epoxide opening (REO) featuring a catalyst-controlled synthesis of enantiomerically and diastereomerically highly enriched or pure syn- and anti- 1,3- and 1,4-difunctionalized building blocks from a common epoxide precursor. The REO is attractive for natural product synthesis and as a branching reaction for diversity-oriented synthesis with epoxides. PMID:27600090

  20. Photoaffinity labeling of opioid receptor with morphine-7,8-oxide (morphine epoxide)

    SciTech Connect

    Takayanagi, I.; Shibata, R.; Miyata, N.; Hirobe, M.

    1982-05-01

    The opioid receptor mediating inhibitory action of morphine in the electrically stimulated guinea pig ileum was irreversibly photoinactivated by morphine epoxide (3 X 10(-6) M). Morphine epoxide (up to 3 X 10(-5) M) did not influence the responses of rat vas deferens (epsilon-receptor) or rabbit vas deferens (kappa-receptor) to electrical stimulation. Effective concentrations of morphine epoxide were much lower in the guinea pig ileum (mu-receptor) than in the mouse vas deference (delta-receptor). The inhibitory action of (Met)-enkephalin on the twitch responses of the rat vas deferens and mouse vas deferens to electrical stimulation were not influenced after irradiation in the presence of morphine epoxide (3 X 10(-6) M). Therefore, morphine epoxide is probably a useful probe for photoaffinity labeling of the mu-receptor in vitro.

  1. Biodegradation of heptachlor and heptachlor epoxide-contaminated soils by white-rot fungal inocula.

    PubMed

    Purnomo, Adi Setyo; Putra, Surya Rosa; Shimizu, Kuniyoshi; Kondo, Ryuichiro

    2014-10-01

    The ability of certain white-rot fungi (WRF) inocula to transform heptachlor and heptachlor epoxide and its application in artificially contaminated soil were investigated. Fungal inoculum of Pleurotus ostreatus eliminated approximately 89 % of heptachlor after 28 days of incubation, and chlordene was detected as the primary metabolite. The fungal inoculum of Pleurotus ostreatus had the highest ability to degrade heptachlor epoxide; approximately 32 % were degraded after 28 days of incubation, and heptachlor diol was detected as the metabolite product. Because Pleurotus ostreatus transformed heptachlor into a less toxic metabolite and could also effectively degrade heptachlor epoxide, it was then selected to be applied to artificially contaminated soil. The spent mushroom waste (SMW) of Pleurotus ostreatus degraded heptachlor and heptachlor epoxide by approximately 91 and 26 %, respectively, over 28 days. This finding indicated that Pleurotus ostreatus SMW could be used to bioremediate heptachlor- and heptachlor epoxide-contaminated environments. PMID:24840358

  2. 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.

  3. 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.

  4. Iron-catalysed propylene epoxidation by nitrous oxide: dramatic shift of allylic oxidation to epoxidation by the modification with alkali metal salts.

    PubMed

    Wang, Xiaoxing; Zhang, Qinghong; Guo, Qian; Lou, Yinchuan; Yang, Lujuan; Wang, Ye

    2004-06-21

    A dramatic shift of allylic oxidation to epoxidation has been observed during the oxidation of propylene by N(2)O when the FeO(x)/SBA-15 catalyst is modified with alkali metal salts, and the roles of alkali metal salts are to suppress the reactivity of lattice oxygen and to induce an iron coordination structure effective for epoxidation with N(2)O. PMID:15179482

  5. 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.

  6. An enzyme catalysing the conjugation of epoxides with glutathione

    PubMed Central

    Boyland, E.; Williams, K.

    1965-01-01

    1. Liver supernatant preparations from rats and ferrets catalyse the conjugation of some epoxides with glutathione. The enzyme involved might be called `glutathione S-epoxidetransferase', as it is different from glutathione S-aryltransferase, the enzyme catalysing the conjugation of 1,2-dichloro-4-nitrobenzene, 4-nitro-pyridine N-oxide and other cyclic compounds with glutathione and from the enzyme catalysing the conjugation of iodomethane and glutathione. 2. The enzyme does not catalyse the reaction with cysteine. It is not inactivated by dialysis but is unstable at pH 5·0. 3. The role of the enzyme in metabolism of foreign compounds is discussed. PMID:14342229

  7. Catalysts for CO2/epoxide ring-opening copolymerization

    PubMed Central

    Trott, G.; Saini, P. K.; Williams, C. K.

    2016-01-01

    This article summarizes and reviews recent progress in the development of catalysts for the ring-opening copolymerization of carbon dioxide and epoxides. The copolymerization is an interesting method to add value to carbon dioxide, including from waste sources, and to reduce pollution associated with commodity polymer manufacture. The selection of the catalyst is of critical importance to control the composition, properties and applications of the resultant polymers. This review highlights and exemplifies some key recent findings and hypotheses, in particular using examples drawn from our own research. PMID:26755758

  8. Catalysts for CO2/epoxide ring-opening copolymerization.

    PubMed

    Trott, G; Saini, P K; Williams, C K

    2016-02-28

    This article summarizes and reviews recent progress in the development of catalysts for the ring-opening copolymerization of carbon dioxide and epoxides. The copolymerization is an interesting method to add value to carbon dioxide, including from waste sources, and to reduce pollution associated with commodity polymer manufacture. The selection of the catalyst is of critical importance to control the composition, properties and applications of the resultant polymers. This review highlights and exemplifies some key recent findings and hypotheses, in particular using examples drawn from our own research. PMID:26755758

  9. Development of optically transparent cyclic olefin photoresist binder resins

    NASA Astrophysics Data System (ADS)

    Rhodes, Larry F.; Chang, Chun; Burns, Cheryl; Barnes, Dennis A.; Bennett, Brian; Seger, Larry; Wu, Xiaoming; Sobek, Andy; Mishak, Mike; Peterson, Craig; Langsdorf, Leah; Hada, Hideo; Shimizu, Hiroaki; Sasaki, Kazuhito

    2005-05-01

    Of all candidate 193 nm photoresist binder resins, transition metal catalyzed vinyl addition cyclic olefin (i.e., norbornene) polymers (PCO) hold the promise of high transparency and excellent etch resistance. In order to access lower molecular weight polymers, which are typically used in photoresists, α-olefin chain transfer agents (CTAs) are used in synthesizing vinyl addition poly(norbornenes). For example, HFANB (α,α-bis(trifluoromethyl)bicyclo [2.2.1]hept-5-ene-2-ethanol) homopolymers (p(HFANB)) with molecular weights (Mn) less than 5000 have been synthesized using such chain transfer agents. However, the optical density (OD) at 193 nm of these materials was found to rise as their molecular weights decreased consistent with a polymer end group effect. Extensive NMR and MS analysis of these polymers revealed that olefinic end groups derived from the chain transfer agent were responsible for the deleterious rise in OD. Chemical modification of these end groups by epoxidation, hydrogenation, hydrosilation, etc. lowers the OD of the polymer by removing the olefinic chromophore, however, it does require a second synthetic step. Thus a new class of non-olefinic chain transfer agents has been developed at Promerus that allow for excellent control of vinyl addition cyclic olefin polymer molecular weight and low optical density without the need of a post-polymerization chemical modification. Low molecular weight homopolymers of HFANB have been synthesized using these chain transfer agents that exhibit ODs <= 0.07 absorbance units per micron. This molecular weight control technology has been applied to both positive tone and negative tone vinyl addition cyclic olefin binder resins. Lithographic and etch performance of positive tone photoresists based on these binder resins will be presented.

  10. 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.

  11. 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.

  12. 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.

  13. Integrated process and dual-function catalyst for olefin epoxidation

    DOEpatents

    Zhou, Bing; Rueter, Michael

    2003-01-01

    The invention discloses a dual-functional catalyst composition and an integrated process for production of olefin epoxides including propylene oxide by catalytic reaction of hydrogen peroxide from hydrogen and oxygen with olefin feeds such as propylene. The epoxides and hydrogen peroxide are preferably produced simultaneously in situ. The dual-functional catalyst comprises noble metal crystallites with dimensions on the nanometer scale (on the order of <1 nm to 10 nm), specially dispersed on titanium silicalite substrate particles. The dual functional catalyst catalyzes both the direct reaction of hydrogen and oxygen to generate hydrogen peroxide intermediate on the noble metal catalyst surface and the reaction of the hydrogen peroxide intermediate with the propylene feed to generate propylene oxide product. Combining both these functions in a single catalyst provides a very efficient integrated process operable below the flammability limits of hydrogen and highly selective for the production of hydrogen peroxide to produce olefin oxides such as propylene oxide without formation of undesired co-products.

  14. Epoxide hydrolase of Trichoderma reesei: Biochemical properties and conformational characterization.

    PubMed

    de Oliveira, Gabriel Stephani; Adriani, Patricia Pereira; Borges, Flavia Garcia; Lopes, Adriana Rios; Campana, Patricia T; Chambergo, Felipe S

    2016-08-01

    Epoxide hydrolases (EHs) are enzymes that are present in all living organisms and catalyze the hydrolysis of epoxides to the corresponding vicinal diols. EHs have biotechnological potential in chiral chemistry. We report the cloning, purification, enzymatic activity, and conformational analysis of the TrEH gene from Trichoderma reesei strain QM9414 using circular dichroism spectroscopy. The EH gene has an open reading frame encoding a protein of 343 amino acid residues, resulting in a molecular mass of 38.2kDa. The enzyme presents an optimum pH of 7.2, and it is highly active at temperatures ranging from 23 to 50°C and thermally inactivated at 70°C (t1/2=7.4min). The Michaelis constants (Km) were 4.6mM for racemic substrate, 21.7mM for (R)-(+)-styrene oxide and 3.0mM for (S)-(-)-styrene oxide. The kcat/Km analysis indicated that TrEH is enantioselective and preferentially hydrolyzes (S)-(-)-styrene oxide. The conformational stability studies suggested that, despite the extreme conditions (high temperatures and extremely acid and basic pHs), TrEH is able to maintain a considerable part of its regular structures, including the preservation of the native cores in some cases. The recombinant protein showed enantioselectivity that was distinct from other fungus EHs, making this protein a potential biotechnological tool. PMID:27177457

  15. Catalysis of potato epoxide hydrolase, StEH1

    PubMed Central

    Elfström, Lisa T.; Widersten, Mikael

    2005-01-01

    The kinetic mechanism of epoxide hydrolase (EC 3.3.2.3) from potato, StEH1 (Solanum tuberosum epoxide hydrolase 1), was studied by presteady-state and steady-state kinetics as well as by pH dependence of activity. The specific activities towards the different enantiomers of TSO (trans-stilbene oxide) as substrate were 43 and 3 μmol·min−1·mg−1 with the R,R- or S,S-isomers respectively. The enzyme was, however, enantioselective in favour of the S,S enantiomer due to a lower Km value. The pH dependences of kcat with R,R or S,S-TSO were also distinct and supposedly reflecting the pH dependences of the individual kinetic rates during substrate conversion. The rate-limiting step for TSO and cis- and trans-epoxystearate was shown by rapid kinetic measurements to be the hydrolysis of the alkylenzyme intermediate. Functional characterization of point mutants verified residues Asp105, Tyr154, Tyr235 and His300 as crucial for catalytic activity. All mutants displayed drastically decreased enzymatic activities during steady state. Presteady-state measurements revealed the base-deficient H300N (His300→Asn) mutant to possess greatly reduced efficiencies in catalysis of both chemical steps (alkylation and hydrolysis). PMID:15882148

  16. 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.

  17. 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.

  18. Aminoacylase 1-catalysed deacetylation of bioactives epoxides mycotoxin-derived mercapturates; 3,4-epoxyprecocenes as models of cytotoxic epoxides.

    PubMed

    Stocker, Pierre; Brunel, Jean Michel; de Rezende, Leandro; do Amaral, Antonia Tavares; Morelli, Xavier; Roche, Phillipe; Vidal, Nicolas; Giardina, Thierry; Perrier, Josette

    2012-08-01

    The mycotoxin aflatoxin B1 (AFB1) is a carcinogenic food contaminant which is metabolically activated by epoxydation. The metabolism of mycotoxins via the mercapturate metabolic pathway was shown, in general, to lead to their detoxication. Mercapturic acids thus formed (S-substitued-N-acetyl-l-cysteines) may be accumulated in the kidney and either excreted in the urine or desacetylated by Acylase 1 (ACY1) to yield cysteine S-conjugates. To be toxic, the N-acetyl-l-cysteine-S-conjugates first have to undergo deacetylation by ACY 1. The specificity and rate of mercapturic acid deacetylation may determine the toxicity, however the exact deacetylation processes involved are not well known. The aim of this study was to investigate the role of ACY1 in the toxicity of some bioactive epoxides from Aflatoxin B1. We characterized the kinetic parameters of porcine kidney and human recombinant aminoacylase-1 towards some aromatic and aliphatic-derived mercapturates analogue of mycotoxin-mercapturic acids and 3,4-epoxyprecocene, a bioactive epoxide derivated from aflatoxin. The deacetylation of mercapturated substrates was followed both by reverse phase HPLC and by TNBS method. Catalytic activity was discussed in a structure-function relationship. Ours results indicate for the first time that aminoacylase-1 could play an important role in deacetylating mercapturate metabolites of aflatoxin analogues and this process may be in relation with their cyto- and nephrotoxicity in human. PMID:22349737

  19. Role of induction of specific hepatic cytochrome P450 isoforms in epoxidation of 4-vinylcyclohexene.

    PubMed

    Fontaine, S M; Hoyer, P B; Halpert, J R; Sipes, I G

    2001-09-01

    4-Vinyl-1-cyclohexene (VCH) is ovotoxic in B6C3F(1) mice but not in Fischer-344 rats, which can be partially attributed to greater formation of toxic epoxides from VCH in mice compared with rats. Since repeated exposure to VCH is necessary to cause ovotoxicity in mice, it is important to determine whether repeated exposure results in induction of cytochrome P450 (CYP) enzymes involved in its bioactivation. Hepatic microsomes prepared from mice or rats treated repeatedly with VCH demonstrated significantly increased VCH bioactivation in vitro, as assessed by VCH-1,2-epoxide, VCH-7,8-epoxide, or vinylcyclohexene diepoxide (VCD) formation. Mice and rats were then dosed with VCH, VCH-1,2-epoxide, or VCD for 10 days and measured for increases in hepatic microsomal CYP levels or activities. Total hepatic CYP levels were elevated only in microsomes from mice pretreated with VCH or VCH-1,2-epoxide. Immunoblotting analysis of microsomes from VCH-treated rodents revealed elevated levels of CYP2A and CYP2B in mice but not rats. VCH-1,2-epoxide pretreatment also increased CYP2B levels in the mouse. Activities toward specific substrates for CYP2A and CYP2B (coumarin and pentoxyresorufin, respectively) confirmed that VCH and VCH-1,2-epoxide pretreatments resulted in increased catalytic activities of CYP2A and CYP2B in the mouse but not the rat. Pretreatment with phenobarbital, a known inducer of CYP2A and CYP2B, increased VCH bioactivation in both species. Interestingly, metabolism studies with human CYP "Supersomes" reveal that, of eight isoforms tested, only human CYP2E1 and CYP2B6 were capable of significantly catalyzing VCH epoxidation, whereas CYP2B6, CYP2A6, CYP2E1, and CYP3A4 were capable of catalyzing the epoxidation of the monoepoxides. PMID:11502734

  20. Cyclic interconversion of vitamin K1 and vitamin K1 2,3-epoxide in man.

    PubMed Central

    Bechtold, H; Trenk, D; Meinertz, T; Rowland, M; Jähnchen, E

    1983-01-01

    The disposition of a single intravenous bolus dose of 10 mg vitamin K1 and vitamin K1-2,3-epoxide were studied in two healthy subjects without and with 12 h pretreatment dose of phenprocoumon (0.4 mg/kg). For each compound administered alone the plasma concentration-time profile was adequately fitted by a biexponential equation, with an average terminal half-life of 2.0 and 1.15 h for the administered vitamin K and its 2,3-epoxide respectively. While vitamin K1 was measurable in plasma following administration of vitamin K1-2,3-epoxide, the epoxide was not detectable following administration of vitamin K1. Following pretreatment with phenprocoumon and after intravenous administration of vitamin K1, both the average half-life and area under the plasma concentration-time profile of vitamin K1 were marginally reduced to 1.5 h and 1.76 mg l-1 h respectively, while the plasma concentration of vitamin K1-2,3-epoxide was readily measurable and its half-life markedly prolonged to 14.7 h. Following pretreatment with phenprocoumon and after oral administration of vitamin K1-2,3-epoxide, no vitamin K1 was detectable in plasma and the half-life of the epoxide was 13.8 h. Based on area considerations the data suggest that either phenprocoumon does more than just inhibit the reduction of vitamin K1-2,3-epoxide to vitamin K1, or that the simple model describing the interconversion between vitamin K1 and its epoxide is inadequate. The same conclusion is drawn from the analysis of comparable data in dogs, obtained by Carlisle & Blaschke (1981). PMID:6661354

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. Data set of optimal parameters for colorimetric red assay of epoxide hydrolase activity.

    PubMed

    de Oliveira, Gabriel Stephani; Adriani, Patricia Pereira; Borges, Flavia Garcia; Lopes, Adriana Rios; Campana, Patricia T; Chambergo, Felipe S

    2016-09-01

    The data presented in this article are related to the research article entitled "Epoxide hydrolase of Trichoderma reesei: Biochemical properties and conformational characterization" [1]. Epoxide hydrolases (EHs) are enzymes that catalyze the hydrolysis of epoxides to the corresponding vicinal diols. This article describes the optimal parameters for the colorimetric red assay to determine the enzymatic activity, with an emphasis on the characterization of the kinetic parameters, pH optimum and thermal stability of this enzyme. The effects of reagents that are not resistant to oxidation by sodium periodate on the reactions can generate false positives and interfere with the final results of the red assay. PMID:27366781

  7. Methods of producing epoxides from alkenes using a two-component catalyst system

    DOEpatents

    Kung, Mayfair C.; Kung, Harold H.; Jiang, Jian

    2013-07-09

    Methods for the epoxidation of alkenes are provided. The methods include the steps of exposing the alkene to a two-component catalyst system in an aqueous solution in the presence of carbon monoxide and molecular oxygen under conditions in which the alkene is epoxidized. The two-component catalyst system comprises a first catalyst that generates peroxides or peroxy intermediates during oxidation of CO with molecular oxygen and a second catalyst that catalyzes the epoxidation of the alkene using the peroxides or peroxy intermediates. A catalyst system composed of particles of suspended gold and titanium silicalite is one example of a suitable two-component catalyst system.

  8. Mechanism of olefin epoxidation in the presence of a titanium-containing zeolite

    NASA Astrophysics Data System (ADS)

    Danov, S. M.; Krasnov, V. L.; Sulimov, A. V.; Ovcharova, A. V.

    2013-11-01

    The effect of the nature of a solvent on the liquid-phase epoxidation of olefins with an aqueous solution of hydrogen peroxide over a titanium-containing zeolite is studied. Butanol-1, butanol-2, propanol-1, isopropanol, methanol, ethanol, water, acetone, methyl ethyl ketone, isobutanol, and tert-butanol are examined as solvents. A mechanism of olefin epoxidation with hydrogen peroxide in an alcohol medium over a titanium-containing zeolite is proposed. Epoxidation reactions involving hydrogen peroxide and different olefins are studied experimentally.

  9. 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.

  10. Olefin Epoxidation in Aqueous Phase Using Ionic-Liquid Catalysts.

    PubMed

    Cokoja, Mirza; Reich, Robert M; Wilhelm, Michael E; Kaposi, Marlene; Schäffer, Johannes; Morris, Danny S; Münchmeyer, Christian J; Anthofer, Michael H; Markovits, Iulius I E; Kühn, Fritz E; Herrmann, Wolfgang A; Jess, Andreas; Love, Jason B

    2016-07-21

    Hydrophobic imidazolium-based ionic liquids (IL) act as catalysts for the epoxidation of unfunctionalized olefins in water using hydrogen peroxide as oxidant. Although the catalysts are insoluble in both the substrate and in water, surprisingly, they are very well soluble in aqueous H2 O2 solution, owing to perrhenate-H2 O2 interactions. Even more remarkably, the presence of the catalyst also boosts the solubility of substrate in water. This effect is crucially dependent on the cation design. Hence, the imidazolium perrhenates enable both the transfer of hydrophobic substrate into the aqueous phase, and serve as actual catalysts, which is unprecedented. At the end of the reaction and in absence of H2 O2 the IL catalyst forms a third phase next to the lipophilic product and water and can easily be recycled. PMID:27219852

  11. Structure of a bacterial homologue of vitamin K epoxide reductase

    SciTech Connect

    Li, Weikai; Schulman, Sol; Dutton, Rachel J.; Boyd, Dana; Beckwith, Jon; Rapoport, Tom A.

    2010-03-19

    Vitamin K epoxide reductase (VKOR) generates vitamin K hydroquinone to sustain {gamma}-carboxylation of many blood coagulation factors. Here, we report the 3.6 {angstrom} crystal structure of a bacterial homologue of VKOR from Synechococcus sp. The structure shows VKOR in complex with its naturally fused redox partner, a thioredoxin-like domain, and corresponds to an arrested state of electron transfer. The catalytic core of VKOR is a four transmembrane helix bundle that surrounds a quinone, connected through an additional transmembrane segment with the periplasmic thioredoxin-like domain. We propose a pathway for how VKOR uses electrons from cysteines of newly synthesized proteins to reduce a quinone, a mechanism confirmed by in vitro reconstitution of vitamin K-dependent disulphide bridge formation. Our results have implications for the mechanism of the mammalian VKOR and explain how mutations can cause resistance to the VKOR inhibitor warfarin, the most commonly used oral anticoagulant.

  12. Conformational diversity and enantioconvergence in potato epoxide hydrolase 1.

    PubMed

    Bauer, P; Carlsson, Å Janfalk; Amrein, B A; Dobritzsch, D; Widersten, M; Kamerlin, S C L

    2016-06-28

    Potato epoxide hydrolase 1 (StEH1) is a biocatalytically important enzyme that exhibits rich enantio- and regioselectivity in the hydrolysis of chiral epoxide substrates. In particular, StEH1 has been demonstrated to enantioconvergently hydrolyze racemic mixes of styrene oxide (SO) to yield (R)-1-phenylethanediol. This work combines computational, crystallographic and biochemical analyses to understand both the origins of the enantioconvergent behavior of the wild-type enzyme, as well as shifts in activities and substrate binding preferences in an engineered StEH1 variant, R-C1B1, which contains four active site substitutions (W106L, L109Y, V141K and I155V). Our calculations are able to reproduce both the enantio- and regioselectivities of StEH1, and demonstrate a clear link between different substrate binding modes and the corresponding selectivity, with the preferred binding modes being shifted between the wild-type enzyme and the R-C1B1 variant. Additionally, we demonstrate that the observed changes in selectivity and the corresponding enantioconvergent behavior are due to a combination of steric and electrostatic effects that modulate both the accessibility of the different carbon atoms to the nucleophilic side chain of D105, as well as the interactions between the substrate and protein amino acid side chains and active site water molecules. Being able to computationally predict such subtle effects for different substrate enantiomers, as well as to understand their origin and how they are affected by mutations, is an important advance towards the computational design of improved biocatalysts for enantioselective synthesis. PMID:27049844

  13. Expanding the Catalytic Triad in Epoxide Hydrolases and Related Enzymes

    PubMed Central

    2015-01-01

    Potato epoxide hydrolase 1 exhibits rich enantio- and regioselectivity in the hydrolysis of a broad range of substrates. The enzyme can be engineered to increase the yield of optically pure products as a result of changes in both enantio- and regioselectivity. It is thus highly attractive in biocatalysis, particularly for the generation of enantiopure fine chemicals and pharmaceuticals. The present work aims to establish the principles underlying the activity and selectivity of the enzyme through a combined computational, structural, and kinetic study using the substrate trans-stilbene oxide as a model system. Extensive empirical valence bond simulations have been performed on the wild-type enzyme together with several experimentally characterized mutants. We are able to computationally reproduce the differences between the activities of different stereoisomers of the substrate and the effects of mutations of several active-site residues. In addition, our results indicate the involvement of a previously neglected residue, H104, which is electrostatically linked to the general base H300. We find that this residue, which is highly conserved in epoxide hydrolases and related hydrolytic enzymes, needs to be in its protonated form in order to provide charge balance in an otherwise negatively charged active site. Our data show that unless the active-site charge balance is correctly treated in simulations, it is not possible to generate a physically meaningful model for the enzyme that can accurately reproduce activity and selectivity trends. We also expand our understanding of other catalytic residues, demonstrating in particular the role of a noncanonical residue, E35, as a “backup base” in the absence of H300. Our results provide a detailed view of the main factors driving catalysis and regioselectivity in this enzyme and identify targets for subsequent enzyme design efforts. PMID:26527505

  14. 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

  15. Vibrational Excitations and Low Energy Electronic Structure of Epoxide-decorated Graphene

    PubMed Central

    Mattson, E.C.; Johns, J.E.; Pande, K.; Bosch, R.A.; Cui, S.; Gajdardziska-Josifovska, M.; Weinert, M.; Chen, J.H.; Hersam, M.C.; Hirschmugl, C.J.

    2014-01-01

    We report infrared studies of adsorbed atomic oxygen (epoxide functional groups) on graphene. Two different systems are used as a platform to explore these interactions, namely, epitaxial graphene/SiC(0001) functionalized with atomic oxygen (graphene epoxide, GE) and chemically reduced graphene oxide (RGO). In the case of the model GE system, IR reflectivity measurements show that epoxide groups distort the graphene π bands around the K-point, imparting a finite effective mass and contributing to a band gap. In the case of RGO, epoxide groups are found to be present following the reduction treatment by a combination of polarized IR reflectance and transmittance measurements. Similar to the GE system, a band gap in the RGO sample is observed as well. PMID:24563725

  16. The Role of Long Chain Fatty Acids and Their Epoxide Metabolites in Nociceptive Signaling

    PubMed Central

    Wagner, Karen; Vito, Steve; Inceoglu, Bora; Hammock, Bruce D.

    2014-01-01

    Lipid derived mediators contribute to inflammation and the sensing of pain. The contributions of omega-6 derived prostanoids in enhancing inflammation and pain sensation are well known. Less well explored are the opposing anti-inflammatory and analgesic effects of the omega-6 derived epoxyeicosatrienoic acids. Far less has been described about the epoxidized metabolites derived from omega-3 long chain fatty acids. The epoxide metabolites are turned over rapidly with enzymatic hydrolysis by the soluble epoxide hydrolase being the major elimination pathway. Despite this, the overall understanding of the role of lipid mediators in the pathology of chronic pain is growing. Here we review the role of long chain fatty acids and their metabolites in alleviating both acute and chronic pain conditions. We focus specifically on the epoxidized metabolites of omega-6 and omega-3 long chain fatty acids as well as a novel strategy to modulate their activity in vivo. PMID:25240260

  17. Regio- and Stereoselective Monoepoxidation of Dienes using Methyltrioxorhenium: Synthesis of Allylic Epoxides

    PubMed Central

    2015-01-01

    Methyltrioxorhenium (MTO) complexed with pyridine was shown to be a highly effective catalyst for the regioselective monoepoxidation of conjugated di- and trienes using 30% H2O2 at or below room temperature. The resultant allylic epoxides, and the triols derived from them, are versatile synthetic intermediates as well as substructures present in many bioactive natural products. The site of epoxidation was dependent upon olefin substitution, olefin geometry (Z vs E), and the presence of electron-withdrawing substituents on adjacent carbons. For 1-acyl(silyl)oxypenta-2,4-dienes, epoxidation of the distal olefin was generally favored in contrast to the adjacent regioselectivity characteristic of Sharpless, peracid, and other directed epoxidations of hydroxylated dienes. PMID:25321319

  18. Biobased composites from thermoplastic polyurethane elastomer and cross-linked acrylated-epoxidized soybean oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean oil is an important sustainable material. Crosslinked acrylated epoxidized soybean oil (AESO) is brittle without flexibility and the incorporation of thermoplastic polyurethane improves its toughness for industrial applications. The hydrophilic functional groups from both oil and polyurethan...

  19. A Computational Study of Acid Catalyzed Aerosol Reactions of Atmospherically Relevant Epoxides

    EPA Science Inventory

    Epoxides are important intermediates of atmospheric isoprene oxidation. Their subsequent reactions in the particle phase lead to the production of organic compounds detected in ambient aerosols. We apply density functional theory to determine the important kinetic factors that ...

  20. Chemoenzymatic Epoxidation of Alkenes and Reusability Study of the Phenylacetic Acid

    PubMed Central

    Abdulmalek, Emilia; Mizan, Hanis Nabillah; Abdul Rahman, Mohd. Basyaruddin; Basri, Mahiran; Salleh, Abu Bakar

    2014-01-01

    Here, we focused on a simple enzymatic epoxidation of alkenes using lipase and phenylacetic acid. The immobilised Candida antarctica lipase B, Novozym 435 was used to catalyse the formation of peroxy acid instantly from hydrogen peroxide (H2O2) and phenylacetic acid. The peroxy phenylacetic acid generated was then utilised directly for in situ oxidation of alkenes. A variety of alkenes were oxidised with this system, resulting in 75–99% yield of the respective epoxides. On the other hand, the phenylacetic acid was recovered from the reaction media and reused for more epoxidation. Interestingly, the waste phenylacetic acid had the ability to be reused for epoxidation of the 1-nonene to 1-nonene oxide, giving an excellent yield of 90%. PMID:24587751

  1. Hydroxyl-Substituted Ladder Polyethers via Selective Tandem Epoxidation/Cyclization Sequence

    PubMed Central

    Czabaniuk, Lara C.; Jamison, Timothy F.

    2015-01-01

    A new and highly selective method for the synthesis of hydroxyl-substituted tetrahydropyrans is described. This method utilizes titanium(IV) iso-propoxide and diethyl tartrate to perform a diastereoselective epoxidation followed by in situ epoxide activation and highly selective endo-cyclization to form the desired tetrahydropyran ring. The HIJ ring fragment of the marine ladder polyether yessotoxin was synthesized using this two-stage tactic that proceeds with high efficiency and excellent regioselectivity. PMID:25647091

  2. Highly Active Titanocene Catalysts for Epoxide Hydrosilylation: Synthesis, Theory, Kinetics, EPR Spectroscopy.

    PubMed

    Henriques, Dina Schwarz G; Zimmer, Katharina; Klare, Sven; Meyer, Andreas; Rojo-Wiechel, Elena; Bauer, Mirko; Sure, Rebecca; Grimme, Stefan; Schiemann, Olav; Flowers, Robert A; Gansäuer, Andreas

    2016-06-27

    A catalytic system for titanocene-catalyzed epoxide hydrosilylation is described. It features a straightforward preparation of titanocene hydrides that leads to a reaction with low catalyst loading, high yields, and high selectivity of radical reduction. The mechanism was studied by a suite of methods, including kinetic studies, EPR spectroscopy, and computational methods. An unusual resting state leads to the observation of an inverse rate order with respect to the epoxide. PMID:27125466

  3. The Epoxidation of Carbonyl Compounds with a Benzyne-Triggered Sulfur Ylide.

    PubMed

    Lou, Mei-Mei; Wang, Han; Song, Li; Liu, Hong-Yi; Li, Zhong-Qiu; Guo, Xiao-Shuang; Zhang, Fu-Geng; Wang, Bin

    2016-07-15

    An efficient method for the synthesis of epoxides from carbonyl compounds, sulfoxides, and benzyne is presented. The strategy involved an epoxidation by a sulfur ylide which is formed in situ from sulfoxide and benzyne through the S-O bond insertion and deprotonation. This one-pot reaction proceeds under mild and base-free conditions, providing a convenient way to introduce the substituted methylene groups onto the carbonyl carbon. PMID:27337065

  4. 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.

  5. 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

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Mutagenic characterization of cholesterol epoxides in Chinese hamster V79 cells.

    PubMed

    Peterson, A R; Peterson, H; Spears, C P; Trosko, J E; Sevanian, A

    1988-10-01

    The uptake, metabolism and alkylating properties of the diastereomeric cholesterol epoxides were studied using Chinese hamster lung fibroblasts (V79 cells). Specific emphasis is given to the comparative cyto- and geno-toxic effects of cholesterol 5 beta,6 beta-epoxide (beta CE) and cholesterol 5 alpha,6 alpha-epoxide (alpha CE) and data are provided for the first time indicating that beta CE can induce more 6-thioguanine-resistant cells than alpha CE. Cholesterol 5 beta,6 beta-epoxide induced colonies of cells resistant to 6-thioguanine at 2-3-fold the frequencies observed with the alpha-isomer, but neither compound produced ouabain-resistant colonies. The cytotoxicity (LD50) of alpha CE was estimated to be 45-50 microM whereas beta CE displayed an LD50 of 25-29 microM. Inhibition of DNA synthesis (IC50) was observed over the same dose ranges as the LD50 for each epoxide isomer. The epoxides were assimilated by cells to an equal extent, however, beta CE was metabolized to cholestane 3 beta,5 alpha-6 beta-triol twice as rapidly as the alpha-isomer. Both epoxides reacted with 4-(4'-nitrobenzyl)-pyridine to a similar extent, and with identical nucleophilic selectivity at pH 7.4, but their alkylating activity was estimated on this basis to be two orders of magnitude less than methyl methanesulfonate. Binding experiments with the DNA or cultured V79 cells or with calf-thymus DNA indicated that interactions were noncovalent and DNA binding did not correlate with the potency of the epoxides to induce the 6-thioguanine-resistant phenotype. Our results could be interpreted as indicating that both cholesterol epoxide isomers are weak mutagens or that they might induce some epigenetic event repressing the hypoxanthine guanine-phosphoribosyltransferase gene. The similarity of the epoxides' alkylating activity and their DNA-binding properties are inconsistent with their different potencies in inducing the 6-thioguanine-resistant phenotype, suggesting that the mechanism leading

  18. Epoxidation Activities of Human Cytochromes P450c17 and P450c21

    PubMed Central

    2015-01-01

    Some cytochrome P450 enzymes epoxidize unsaturated substrates, but this activity has not been described for the steroid hydroxylases. Physiologic steroid substrates, however, lack carbon–carbon double bonds in the parts of the pregnane molecules where steroidogenic hydroxylations occur. Limited data on the reactivity of steroidogenic P450s toward olefinic substrates exist, and the study of occult activities toward alternative substrates is a fundamental aspect of the growing field of combinatorial biosynthesis. We reasoned that human P450c17 (steroid 17-hydroxylase/17,20-lyase, CYP17A1), which 17- and 16α-hydroxylates progesterone, might catalyze the formation of the 16α,17-epoxide from 16,17-dehydroprogesterone (pregna-4,16-diene-3,20-dione). CYP17A1 catalyzed the novel 16α,17-epoxidation and the ordinarily minor 21-hydroxylation of 16,17-dehydroprogesterone in a 1:1 ratio. CYP17A1 mutation A105L, which has reduced progesterone 16α-hydroxylase activity, gave a 1:5 ratio of epoxide:21-hydroxylated products. In contrast, human P450c21 (steroid 21-hydroxylase, CYP21A2) converted 16,17-dehydroprogesterone to the 21-hydroxylated product and only a trace of epoxide. CYP21A2 mutation V359A, which has significant 16α-hydroxylase activity, likewise afforded the 21-hydroxylated product and slightly more epoxide. CYP17A1 wild-type and mutation A105L do not 21- or 16α-hydroxylate pregnenolone, but the enzymes 21-hydroxylated and 16α,17-epoxidized 16,17-dehydropregnenolone (pregna-5,16-diene-3β-ol-20-one) in 4:1 or 12:1 ratios, respectively. Catalase and superoxide dismutase did not prevent epoxide formation. The progesterone epoxide was not a time-dependent, irreversible CYP17A1 inhibitor. Our substrate modification studies have revealed occult epoxidase and 21-hydroxylase activities of CYP17A1, and the fraction of epoxide formed correlated with the 16α-hydroxylase activity of the enzymes. PMID:25386927

  19. 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.

  20. 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.

  1. Epoxide Opening of a 7,17-Seco-7,8-Epoxy-C19-Diterpenoid Alkaloid.

    PubMed

    Ji, Hong; Wang, Feng-Peng; Chen, Qiao-Hong

    2015-12-01

    A new and effective approach toward epoxide opening of a 7,17-seco-7,8-epoxy-C19-diterpenoid alkaloid is herein described. The starting epoxide was prepared from naturally occurring yunnaconitine via a nine-step transformation. Treatment of this epoxide with trifluoroacetic anhydride in dioxane at 110 degrees C followed by reduction with sodium boron hydride generated two epoxide opening compounds 7 and 8. Each of their structures is characteristic of a Δ8,15 bridgehead double bond and a 7β-oxygen-substituted group. PMID:26882668

  2. Impact of Stereochemistry on Ligand Binding: X-ray Crystallographic Analysis of an Epoxide-Based HIV Protease Inhibitor.

    PubMed

    Benedetti, Fabio; Berti, Federico; Campaner, Pietro; Fanfoni, Lidia; Demitri, Nicola; Olajuyigbe, Folasade M; De March, Matteo; Geremia, Silvano

    2014-09-11

    A new pseudopeptide epoxide inhibitor, designed for irreversible binding to HIV protease (HIV-PR), has been synthesized and characterized in solution and in the solid state. However, the crystal structure of the complex obtained by inhibitor-enzyme cocrystallization revealed that a minor isomer, with inverted configuration of the epoxide carbons, has been selected by HIV-PR during crystallization. The structural characterization of the well-ordered pseudopeptide, inserted in the catalytic channel with its epoxide group intact, provides deeper insights into inhibitor binding and HIV-PR stereoselectivity, which aids development of future epoxide-based HIV inhibitors. PMID:25221650

  3. 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).

  4. Mechanical properties and magnetocaloric effects in La(Fe, Si)13 hydrides bonded with different epoxy resins

    NASA Astrophysics Data System (ADS)

    Zhang, Hu; Sun, YuJie; Li, YaWei; Wu, YuanYuan; Long, Yi; Shen, Jun; Hu, FengXia; Sun, JiRong; Shen, BaoGen

    2015-02-01

    The mechanical properties and magnetocaloric effect (MCE) of bonded La(Fe, Si)13 hydrides have been studied in detail. The mechanical strength increases with increasing the grade of epoxy resin from E-20 to E-51. This occurs because more pores and boundaries are filled with high grade resin since high epoxide content increases the degree of crosslinking and reduces the viscosity and shrinkage of resin. The compressive strength reaches 162 MPa for the bonded LaFe11.7Si1.3C0.2H1.8 with 3 wt. % E-51, which is 35% higher than that of bulk LaFe11.7Si1.3C0.2 compound (120 MPa). The mass ΔSM values remain almost same in bonded hydrides and are in a good agreement with the theoretical value. The maximum volumetric ΔSM values are 61.8, 58.0, and 54.7 mJ/cm3 K for bonded hydrides with epoxy resins E-20, E-44, and E-51, respectively, much higher than those of some magnetocaloric materials in same temperature range. The improved mechanical properties and large MCE indicate that bonded LaFe11.7Si1.3C0.2H1.8 is a promising material for room temperature magnetic refrigeration.

  5. Epoxide-Mediated Differential Packaging of Cif and Other Virulence Factors into Outer Membrane Vesicles

    PubMed Central

    Ballok, Alicia E.; Filkins, Laura M.; Bomberger, Jennifer M.; Stanton, Bruce A.

    2014-01-01

    Pseudomonas aeruginosa produces outer membrane vesicles (OMVs) that contain a number of secreted bacterial proteins, including phospholipases, alkaline phosphatase, and the CFTR inhibitory factor (Cif). Previously, Cif, an epoxide hydrolase, was shown to be regulated at the transcriptional level by epoxides, which serve as ligands of the repressor, CifR. Here, we tested whether epoxides have an effect on Cif levels in OMVs. We showed that growth of P. aeruginosa in the presence of specific epoxides but not a hydrolysis product increased Cif packaging into OMVs in a CifR-independent fashion. The outer membrane protein, OprF, was also increased under these conditions, but alkaline phosphatase activity was not significantly altered. Additionally, we demonstrated that OMV shape and density were affected by epoxide treatment, with two distinct vesicle fractions present when cells were treated with epibromohydrin (EBH), a model epoxide. Vesicles isolated from the two density fractions exhibited different protein profiles in Western blotting and silver staining. We have shown that a variety of clinically or host-relevant treatments, including antibiotics, also alter the proteins packaged in OMVs. Proteomic analysis of purified OMVs followed by an analysis of transposon mutant OMVs yielded mutants with altered vesicle packaging. Finally, epithelial cell cytotoxicity was reduced in the vesicles formed in the presence of EBH, suggesting that this epoxide alters the function of the OMVs. Our data support a model whereby clinically or host-relevant signals mediate differential packaging of virulence factors in OMVs, which results in functional consequences for host-pathogen interactions. PMID:25112474

  6. Final Report: Experimental and Theoretical Studies of Surface Oxametallacycles - Connections to Heterogeneous Olefin Epoxidation

    SciTech Connect

    Mark A. Barteau

    2009-09-15

    This project has aimed at the rational design of catalysts for direct epoxidation of olefins. This chemistry remains one of the most challenging problems in heterogeneous catalysis. Although the epoxidation of ethylene by silver catalysts to form ethylene oxide (EO) has been practiced for decades, little progress has been made in expanding this technology to other products and processes. We have made significant advances through the combination of surface science experiments, Density Functional Theory (DFT) calculations, and catalytic reactor experiments, toward understanding the mechanism of this reaction on silver catalysts, and to the rational improvement of selectivity. The key has been our demonstration of surface oxametallacycle intermediates as the species that control reaction selectivity. This discovery permits the influence of catalyst promoters on selectivity to be probed, and new catalyst formulations to be developed. It also guides the development of new chemistry with potential for direct epoxidation of more complex olefins. During the award period we have focused on 1. the formation and reaction selectivity of complex olefin epoxides on silver surfaces, and 2. the influence of co-adsorbed oxygen atoms on the reactions of surface oxametallacycles on silver, and 3. the computational prediction, synthesis, characterization and experimental evaluation of bimetallic catalysts for ethylene epoxidation. The significance of these research thrusts is as follows. Selective epoxidation of olefins more complex than ethylene requires suppression of not only side reactions available to the olefin such as C-H bond breaking, but it requires formation and selective ring closure of the corresponding oxametallacycle intermediates. The work carried out under this grant has significantly advanced the field of catalyst design from first principles. The combination of computational tools, surface science, and catalytic reactor experiments in a single laboratory has few

  7. Purification of a vitamin K epoxide reductase that catalyzes conversion of vitamin K 2,3-epoxide to 3-hydroxy-2-methyl-3-phytyl-2,3-dihydronaphthoquinone.

    PubMed Central

    Mukharji, I; Silverman, R B

    1985-01-01

    An enzyme from bovine liver microsomes that catalyzes the reduction of vitamin K 2,3-epoxide to 2- and 3-hydroxy-2-methyl-3-phytyl-2,3-dihydronaphthoquinone was purified 1152-fold to apparent homogeneity. Microsomes were solubilized with 3-[3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), and the enzyme was purified by chromatography on PBE-94 ion exchanger, hydroxylapatite, and DEAE-cellulose, and then gel filtration on Sephacryl S-200. The homogeneity of the final preparation was established by polyacrylamide slab gel electrophoresis in the presence of sodium dodecyl sulfate. The molecular weight of the native enzyme is 25,000 and that of denatured enzyme is 12,400, which suggests that the enzyme is a dimer with identical subunits. No chromophoric cofactors are associated with the enzyme. Dithiothreitol and CHAPS are essential for activity, but high concentrations of glycerol reduces the activity. The enzyme is not inhibited by warfarin, a potent inhibitor of the vitamin K epoxide reductase, which catalyzes the conversion of vitamin K 2,3-epoxide to vitamin K. Evidence is presented indicating that the purified enzyme is not simply a fragment of the warfarin-sensitive vitamin K epoxide reductase. Images PMID:3857611

  8. Soluble Epoxide Hydrolase Dimerization Is Required for Hydrolase Activity*

    PubMed Central

    Nelson, Jonathan W.; Subrahmanyan, Rishi M.; Summers, Sol A.; Xiao, Xiangshu; Alkayed, Nabil J.

    2013-01-01

    Soluble epoxide hydrolase (sEH) plays a key role in the metabolic conversion of the protective eicosanoid 14,15-epoxyeicosatrienoic acid to 14,15-dihydroxyeicosatrienoic acid. Accordingly, inhibition of sEH hydrolase activity has been shown to be beneficial in multiple models of cardiovascular diseases, thus identifying sEH as a valuable therapeutic target. Recently, a common human polymorphism (R287Q) was identified that reduces sEH hydrolase activity and is localized to the dimerization interface of the protein, suggesting a relationship between sEH dimerization and activity. To directly test the hypothesis that dimerization is essential for the proper function of sEH, we generated mutations within the sEH protein that would either disrupt or stabilize dimerization. We quantified the dimerization state of each mutant using a split firefly luciferase protein fragment-assisted complementation system. The hydrolase activity of each mutant was determined using a fluorescence-based substrate conversion assay. We found that mutations that disrupted dimerization also eliminated hydrolase enzymatic activity. In contrast, a mutation that stabilized dimerization restored hydrolase activity. Finally, we investigated the kinetics of sEH dimerization and found that the human R287Q polymorphism was metastable and capable of swapping dimer partners faster than the WT enzyme. These results indicate that dimerization is required for sEH hydrolase activity. Disrupting sEH dimerization may therefore serve as a novel therapeutic strategy for reducing sEH hydrolase activity. PMID:23362272

  9. Soluble epoxide hydrolase dimerization is required for hydrolase activity.

    PubMed

    Nelson, Jonathan W; Subrahmanyan, Rishi M; Summers, Sol A; Xiao, Xiangshu; Alkayed, Nabil J

    2013-03-15

    Soluble epoxide hydrolase (sEH) plays a key role in the metabolic conversion of the protective eicosanoid 14,15-epoxyeicosatrienoic acid to 14,15-dihydroxyeicosatrienoic acid. Accordingly, inhibition of sEH hydrolase activity has been shown to be beneficial in multiple models of cardiovascular diseases, thus identifying sEH as a valuable therapeutic target. Recently, a common human polymorphism (R287Q) was identified that reduces sEH hydrolase activity and is localized to the dimerization interface of the protein, suggesting a relationship between sEH dimerization and activity. To directly test the hypothesis that dimerization is essential for the proper function of sEH, we generated mutations within the sEH protein that would either disrupt or stabilize dimerization. We quantified the dimerization state of each mutant using a split firefly luciferase protein fragment-assisted complementation system. The hydrolase activity of each mutant was determined using a fluorescence-based substrate conversion assay. We found that mutations that disrupted dimerization also eliminated hydrolase enzymatic activity. In contrast, a mutation that stabilized dimerization restored hydrolase activity. Finally, we investigated the kinetics of sEH dimerization and found that the human R287Q polymorphism was metastable and capable of swapping dimer partners faster than the WT enzyme. These results indicate that dimerization is required for sEH hydrolase activity. Disrupting sEH dimerization may therefore serve as a novel therapeutic strategy for reducing sEH hydrolase activity. PMID:23362272

  10. [Determination of epoxidized soybean oil in bottled foods].

    PubMed

    Kawamura, Yoko; Kanno, Shinji; Mutsuga, Motoh; Tanamoto, Kenichi

    2006-12-01

    A determination method for epoxidized soybean oil (ESBO) in bottled foods was developed and used to survey bottled foods on the Japanese market. The amount of sample required was decreased to 20 g and the standard addition method was adopted for the quantification, because lipid in foods interrupted the hydrolysis of ESBO. The recoveries were 87.1 and 98.9% and the determination limit was 5.0 microg/g for a 20 g sample, be cause lipid in foods interupted the hydrolysis of ESBO. The recoveries using the internal standard method varied widely, because hydrolysis of the internal standard, cis-11,14-eicosadienoic acid ethyl ester, was affected more than that of ESBO by coexisting lipid in the sample. ESBO was not detected in any of the bottled baby food samples examined (14 samples), though it had been frequently detected in previous European surveys. This difference may be related to the low fat content and low fluidity of the bottled baby foods retailed in Japan. On the other hand, ESBO was detected at levels of 25.7-494.0 microg/g in liver paste, pasta sauce, Sungan in spicy oil, and spicy oil. These foods had higher fat content and higher fluidity. However, ESBO intake from these foods appears unlikely to exceed the TDI in the EU (1 mg/kg bw/day). PMID:17228787

  11. Discovery of enantioselectivity of urea inhibitors of soluble epoxide hydrolase.

    PubMed

    Manickam, Manoj; Pillaiyar, Thanigaimalai; Boggu, PullaReddy; Venkateswararao, Eeda; Jalani, Hitesh B; Kim, Nam-Doo; Lee, Seul Ki; Jeon, Jang Su; Kim, Sang Kyum; Jung, Sang-Hun

    2016-07-19

    Soluble epoxide hydrolase (sEH) hydrolyzes epoxyeicosatrienoic acids (EETs) in the metabolic pathway of arachidonic acid and has been considered as an important therapeutic target for chronic diseases such as hypertension, diabetes and inflammation. Although many urea derivatives are known as sEH inhibitors, the enantioselectivity of the inhibitors is not highlighted in spite of the stereoselective hydrolysis of EETs by sEH. In an effort to explore the importance of enantioselectivity in the urea scaffold, a series of enantiomers with the stereocenter adjacent to the urea nitrogen atom were prepared. The selectivity of enantiomers of 1-(α-alkyl-α-phenylmethyl)-3-(3-phenylpropyl)ureas showed wide range differences up to 125 fold with the low IC50 value up to 13 nM. The S-configuration with planar phenyl and small alkyl groups at α-position is crucial for the activity and selectivity. However, restriction of the free rotation of two α-groups with indan-1-yl or 1,2,3,4-tetrahydronaphthalen-1-yl moiety abolishes the selectivity between the enantiomers, despite the increase in activity up to 13 nM. The hydrophilic group like sulfonamido group at para position of 3-phenylpropyl motif of 1-(α-alkyl-α-phenylmethyl-3-(3-phenylpropyl)urea improves the activity as well as enantiomeric selectivity. All these ureas are proved to be specific inhibitor of sEH without inhibition against mEH. PMID:27092411

  12. Soluble epoxide hydrolase: A potential target for metabolic diseases.

    PubMed

    He, Jinlong; Wang, Chunjiong; Zhu, Yi; Ai, Ding

    2016-05-01

    Epoxyeicosatrienoic acids (EETs), important lipid mediators derived from arachidonic acid, have many beneficial effects in metabolic diseases, including atherosclerosis, hypertension, cardiac hypertrophy, diabetes, non-alcoholic fatty liver disease, and kidney disease. Epoxyeicosatrienoic acids can be further hydrolyzed to less active diols by the enzyme soluble epoxide hydrolase (sEH). Increasing evidence suggests that inhibition of sEH increases levels of EETs, which have anti-inflammatory effects and can prevent the development of hypertension, atherosclerosis, heart failure, fatty liver, and multiple organ fibrosis. Arachidonic acid is the most abundant omega-6 polyunsaturated fatty acid (PUFA) and shares the same set of enzymes with omega-3 PUFAs, such as docosahexaenoic acid and eicosapentaenoic acid. The omega-3 PUFAs and metabolites, such as regioisomeric epoxyeicosatetraenoic acids and epoxydocosapentaenoic acids, have been reported to have strong vasodilatory and anti-inflammatory effects. Therefore, sEH may be a potential therapeutic target for metabolic disorders. In this review, we focus on our and other recent studies of the functions of sEH, including the effects of its eicosanoid products from both omega-3 and omega-6 PUFAs, in various metabolic diseases. We also discuss the possible cellular and molecular mechanisms underlying the regulation of sEH. PMID:26621325

  13. Soluble epoxide hydrolase deficiency ameliorates acute pancreatitis in mice.

    PubMed

    Bettaieb, Ahmed; Morisseau, Christophe; Hammock, Bruce; Haj, Fawaz

    2014-10-01

    Acute pancreatitis (AP) is a frequent gastrointestinal disorder that causes significant morbidity and its incidence has been progressively increasing. AP starts as a local inflammation in the pancreas that often leads to systemic inflammatory response and complications. Soluble epoxide hydrolase (sEH) is a cytosolic enzyme whose inhibition in murine models has beneficial effects in inflammatory diseases, but its significance in AP remains unexplored. To investigate whether sEH may have a causal role in AP we utilized sEH knockout (KO) mice to determine the effects of sEH deficiency on ceruelin- and arginine-induced AP. sEH expression increased at the protein and messenger RNA levels, as well as sEH activity in the early phase of cerulein- and arginine-induced AP in mice. In addition, amylase and lipase levels were lower in cerulein-treated sEH KO mice compared with non-treated controls. Moreover, pancreatic mRNA and serum concentrations of the inflammatory cytokines IL-1ß and IL-6 were lower in sEH KO mice compared with controls. Further, sEH KO mice exhibited decreased cerulein- and arginine-induced NF-?B inflammatory response, MAPKs activation and decreased cell death. These findings demonstrate a novel role for sEH in the progression of cerulein- and arginine-induced AP. PMID:26461340

  14. Disrupting Dimerization Translocates Soluble Epoxide Hydrolase to Peroxisomes

    PubMed Central

    Nelson, Jonathan W.; Das, Anjali J.; Barnes, Anthony P.; Alkayed, Nabil J.

    2016-01-01

    The epoxyeicosatrienoic acid (EET) neutralizing enzyme soluble epoxide hydrolase (sEH) is a neuronal enzyme, which has been localized in both the cytosol and peroxisomes. The molecular basis for its dual localization remains unclear as sEH contains a functional peroxisomal targeting sequence (PTS). Recently, a missense polymorphism was identified in human sEH (R287Q) that enhances its peroxisomal localization. This same polymorphism has also been shown to generate weaker sEH homo-dimers. Taken together, these observations suggest that dimerization may mask the sEH PTS and prevent peroxisome translocation. In the current study, we test the hypothesis that dimerization is a key regulator of sEH subcellular localization. Specifically, we altered the dimerization state of sEH by introducing substitutions in amino acids responsible for the dimer-stabilizing salt-bridge. Green Fluorescent Protein (GFP) fusions of each of mutants were co-transfected into mouse primary cultured cortical neurons together with a PTS-linked red fluorescent protein to constitutively label peroxisomes. Labeled neurons were analyzed using confocal microscopy and co-localization of sEH with peroxisomes was quantified using Pearson’s correlation coefficient. We find that dimer-competent sEH constructs preferentially localize to the cytosol, whereas constructs with weakened or disrupted dimerization were preferentially targeted to peroxisomes. We conclude that the sEH dimerization status is a key regulator of its peroxisomal localization. PMID:27203283

  15. GENETIC VARIATION IN SOLUBLE EPOXIDE HYDROLASE (EPHX2) AND RISK OF CORONARY HEART DISEASE: THE ATHEROSCLEROSIS RISK IN COMMUNITIES (ARIC) STUDY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Endothelial dysfunction contributes to the development of coronary heart disease (CHD). Soluble epoxide hydrolase metabolizes epoxyeicosatrienoic acids in the vasculature and regulates endothelial function. We sought to determine whether genetic variation in soluble epoxide hydrolase (EPHX2) was ass...

  16. Genetic variation in soluble epoxide hydrolase (EPHX2) and risk of coronary heart disease: The Atherosclerosis Risk in Communities (ARIC) study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Endothelial dysfunction contributes to the development of coronary heart disease (CHD). Soluble epoxide hydrolase metabolizes epoxyeicosatrienoic acids in the vasculature and regulates endothelial function. We sought to determine whether genetic variation in soluble epoxide hydrolase (EPHX2) was ass...

  17. Synthesis and physicochemical properties of epoxidized Tmp trioleate by in situ method

    NASA Astrophysics Data System (ADS)

    Samidin, Salma; Salimon, Jumat

    2014-09-01

    Tmp trioleate was initially synthesized via esterification of trimetilolprapane and oleic acid (90%) using 1.5% of H2SO4 as a catalyst. The production of Tmp trioleate was observed at 98% (w/w). The iodine value of Tmp trioleate was analyzed for further reaction of epoxidation. Epoxide was important reaction as an intermediate for preparation of chemical modified lubricants from vegetable oils. Finding the best way of epoxidation process will give high quality for further modification of oil instead of reduce the cost and time for the preparation process during reaction of epoxidation. In this study, the epoxidation of unsaturation Tmp trioleate with peroxyformic acid generated in-situ from hydrogen peroxide 30% in H2O2 with formic acid was studied. 95% conversion to oxygen oxirane content (OOC) ring was obtained. The derivatization showed an improvement of the compound's oxidative stability evidenced from pressurized differential scanning calorimetry (PDSC) data which are 177°C to 200°C. Physicochemical properties showed increasing of temperature of flash point from 280°C to 300°C and viscosity index (VI) from 146 to 154. However, the pour point showed increasing temperature which was -58.81°C to -17.32°C. From the data obtained, these derivatives have shown better performance of lubricity properties. Overall, the data indicates that these performances are compatible to the commercial lubricants.

  18. Synthesis and physicochemical properties of epoxidized Tmp trioleate by in situ method

    SciTech Connect

    Samidin, Salma; Salimon, Jumat

    2014-09-03

    Tmp trioleate was initially synthesized via esterification of trimetilolprapane and oleic acid (90%) using 1.5% of H{sub 2}SO{sub 4} as a catalyst. The production of Tmp trioleate was observed at 98% (w/w). The iodine value of Tmp trioleate was analyzed for further reaction of epoxidation. Epoxide was important reaction as an intermediate for preparation of chemical modified lubricants from vegetable oils. Finding the best way of epoxidation process will give high quality for further modification of oil instead of reduce the cost and time for the preparation process during reaction of epoxidation. In this study, the epoxidation of unsaturation Tmp trioleate with peroxyformic acid generated in-situ from hydrogen peroxide 30% in H{sub 2}O{sub 2} with formic acid was studied. 95% conversion to oxygen oxirane content (OOC) ring was obtained. The derivatization showed an improvement of the compound's oxidative stability evidenced from pressurized differential scanning calorimetry (PDSC) data which are 177°C to 200°C. Physicochemical properties showed increasing of temperature of flash point from 280°C to 300°C and viscosity index (VI) from 146 to 154. However, the pour point showed increasing temperature which was −58.81°C to −17.32°C. From the data obtained, these derivatives have shown better performance of lubricity properties. Overall, the data indicates that these performances are compatible to the commercial lubricants.

  19. Zirconium phenylphosphonate-anchored methyltrioxorhenium as novel heterogeneous catalyst for epoxidation of cyclohexene.

    PubMed

    He, Sha; Liu, Xin; Zhao, Hongyue; Zhu, Yue; Zhang, Fazhi

    2015-01-01

    Epoxidation of olefins to epoxides is widely recognized as an important unit process in the manufacture of fine chemicals and intermediates. Developing an environmentally benign heterogeneous catalytic system for olefin epoxidation with high activity and selectivity is still a challenge in this research field. Herein, we report our attempts to synthesize novel zirconium phenylphosphonate-anchored methyltrioxorhenium (MTO/ZrPP) heterogeneous catalysts by a conventional impregnation method and evaluate their catalytic performance for epoxidation of cyclohexene using urea-hydrogen peroxide adduct (UHP) as oxidant without the addition of base ligands. The MTO/ZrPP catalyst samples are characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), inductively coupled plasma emission spectrometry (ICP-ES), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and solid-state (1)H magic-angle spinning nuclear magnetic resonance ((1)H MAS NMR) techniques. Meanwhile, the density functional theory (DFT) calculation is carried out to further understand the structure feature and interactions of the MTO/ZrPP catalyst. It is revealed that MTO is anchored on support surface by the favored hydrogen-bonding interaction between two oxo ligands of MTO and two H atoms from the adjacent phenyls of ZrPP. MTO/ZrPP catalyst displays excellent catalytic activity for cyclohexene epoxidation. Moreover, only cyclohexene oxide production can be obtained under the employed reaction conditions. PMID:25313467

  20. 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.

  1. 40 CFR 63.1427 - Process vent requirements for processes using extended cookout as an epoxide emission reduction...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., liters. Dliq, i = Density of reactor liquid, kg/liter. Cvap, i = Concentration of epoxide in the reactor... end of the ECO, liters. Dliq, f = Density of reactor liquid, kg/liter. Cvap, f = Concentration of... liquid at the point in time when all epoxide has been added to the reactor and prior to any venting....

  2. 40 CFR 63.1427 - Process vent requirements for processes using extended cookout as an epoxide emission reduction...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., weight percent. Vliq, i = Volume of reactor liquid at the onset of the ECO, liters. Dliq, i = Density of.... Dliq, f = Density of reactor liquid, kg/liter. Cvap, f = Concentration of epoxide in the reactor vapor... operator shall determine the concentration of epoxide in the reactor liquid at the point in time when...

  3. 40 CFR 63.1427 - Process vent requirements for processes using extended cookout as an epoxide emission reduction...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., weight percent. Vliq, i = Volume of reactor liquid at the onset of the ECO, liters. Dliq, i = Density of.... Dliq, f = Density of reactor liquid, kg/liter. Cvap, f = Concentration of epoxide in the reactor vapor... operator shall determine the concentration of epoxide in the reactor liquid at the point in time when...

  4. A biotechnological approach to the synthesis of epoxides: bioconversion of hydrocarbons by Pseudomonas oleovorans during growth in a multiphase system

    SciTech Connect

    De Smet, M.J.

    1983-04-01

    This communication examines the oxidation of alkanes and alkenes by Pseudomonas oleovorans. A variety of substrates were tested in order to extend the practical use of P. oleovorans for the synthesis of chiral epoxides. Concludes that hydrocarbon fermentations of P. oleovorans might be an important tool not only in the production of epoxides but also in the production of aliphatic polyesters and biosurfactants.

  5. Epoxidation of alkenes through oxygen activation over a bifunctional CuO/Al2O3 catalyst.

    PubMed

    Scotti, Nicola; Ravasio, Nicoletta; Zaccheria, Federica; Psaro, Rinaldo; Evangelisti, Claudio

    2013-03-01

    The epoxidation of alkenes was carried out over a CuO/Al(2)O(3) catalyst using cumene as an oxygen carrier, through a one-pot reaction, giving high conversion and selectivity with different substrates. Trans-β-methylstyrene gave the corresponding epoxide in 95% yield after 3 h. PMID:23358661

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Increased Silver Activity for Direct Propylene Epoxidation via Subnanometer Size Effects

    SciTech Connect

    Lei, Y.; Mehmood, Faisal; Lee, Sang Soo; Greeley, Jeffrey P.; Lee, Byeongdu; Seifert, Soenke; Winans, R. E.; Elam, J. W.; Meyer, R. J.; Redfern, Paul C.; Teschner, D.; Schlogl, Robert; Pellin, M. J.; Curtiss, Larry A.; Vajda, S.

    2010-04-09

    Production of the industrial chemical propylene oxide is energy-intensive and environmentally unfriendly. Catalysts based on bulk silver surfaces with direct propylene epoxidation by molecular oxygen have not resolved these problems because of substantial formation of carbon dioxide. We found that unpromoted, size-selected Ag3 clusters and ~3.5-nanometer Ag nanoparticles on alumina supports can catalyze this reaction with only a negligible amount of carbon dioxide formation and with high activity at low temperatures. Density functional calculations show that, relative to extended silver surfaces, oxidized silver trimers are more active and selective for epoxidation because of the open-shell nature of their electronic structure. The results suggest that new architectures based on ultrasmall silver particles may provide highly efficient catalysts for propylene epoxidation.

  12. A broadly applicable and practical oligomeric (salen) Co catalyst for enantioselective epoxide ring-opening reactions

    PubMed Central

    White, David E.; Tadross, Pamela M.; Lu, Zhe

    2014-01-01

    The (salen) Co catalyst (4a) can be prepared as a mixture of cyclic oligomers in a short, chromatography-free synthesis from inexpensive, commercially available precursors. This catalyst displays remarkable enhancements in reactivity and enantioselectivity relative to monomeric and other multimeric (salen) Co catalysts in a wide variety of enantioselective epoxide ring-opening reactions. The application of catalyst 4a is illustrated in the kinetic resolution of terminal epoxides by nucleophilic ring-opening with water, phenols, and primary alcohols; the desymmetrization of meso epoxides by addition of water and carbamates; and the desymmetrization of oxetanes by intramolecular ring opening with alcohols and phenols. The favorable solubility properties of complex 4a under the catalytic conditions facilitated mechanistic studies, allowing elucidation of the basis for the beneficial effect of oligomerization. Finally, a catalyst selection guide is provided to delineate the specific advantages of oligomeric catalyst 4a relative to (salen) Co monomer 1 for each reaction class. PMID:25045188

  13. Copper nanocrystal plane effect on stereoselectivity of catalytic deoxygenation of aromatic epoxides.

    PubMed

    Xiao, Bin; Niu, Zhiqiang; Wang, Yang-Gang; Jia, Wei; Shang, Jian; Zhang, Lan; Wang, Dingsheng; Fu, Yao; Zeng, Jie; He, Wei; Wu, Kai; Li, Jun; Yang, Jinlong; Liu, Lei; Li, Yadong

    2015-03-25

    Previous studies have shown that crystal planes of heterogeneous catalysts could display enhanced activity, such that higher turnover or chemoselectivity could be achieved. Here we report an example where the reaction stereoselectivity was significantly affected by the catalyst crystal planes. In copper-catalyzed deoxygenation reaction of aromatic epoxides, copper cubes, wires, and plates gave the olefin products with different cis/trans selectivities, whereas homogeneous copper catalysts showed poor selectivity. Scanning tunneling microscope and density functional theory studies revealed that the different adsorption mode and higher adsorption strength of epoxide oxygen on Cu{100} plane were responsible for the observed variation of selectivity. The copper-catalyzed deoxygenation reaction provided new practical access to cis-olefins from readily available aromatic epoxides. Our work also indicated that nanocrystal catalysts may provide useful stereochemical control in organic reactions. PMID:25778784

  14. Inhibiting an Epoxide Hydrolase Virulence Factor from Pseudomonas aeruginosa Protects CFTR.

    PubMed

    Bahl, Christopher D; Hvorecny, Kelli L; Bomberger, Jennifer M; Stanton, Bruce A; Hammock, Bruce D; Morisseau, Christophe; Madden, Dean R

    2015-08-17

    Opportunistic pathogens exploit diverse strategies to sabotage host defenses. Pseudomonas aeruginosa secretes the CFTR inhibitory factor Cif and thus triggers loss of CFTR, an ion channel required for airway mucociliary defense. However, the mechanism of action of Cif has remained unclear. It catalyzes epoxide hydrolysis, but there is no known role for natural epoxides in CFTR regulation. It was demonstrated that the hydrolase activity of Cif is strictly required for its effects on CFTR. A small-molecule inhibitor that protects this key component of the mucociliary defense system was also uncovered. These results provide a basis for targeting the distinctive virulence chemistry of Cif and suggest an unanticipated role of physiological epoxides in intracellular protein trafficking. PMID:26136396

  15. 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.

  16. Soluble epoxide hydrolase limits mechanical hyperalgesia during inflammation

    PubMed Central

    2011-01-01

    Background Cytochrome-P450 (CYP450) epoxygenases metabolise arachidonic acid (AA) into four different biologically active epoxyeicosatrienoic acid (EET) regioisomers. Three of the EETs (i.e., 8,9-, 11,12- and 14,15-EET) are rapidly hydrolysed by the enzyme soluble epoxide hydrolase (sEH). Here, we investigated the role of sEH in nociceptive processing during peripheral inflammation. Results In dorsal root ganglia (DRG), we found that sEH is expressed in medium and large diameter neurofilament 200-positive neurons. Isolated DRG-neurons from sEH-/- mice showed higher EET and lower DHET levels. Upon AA stimulation, the largest changes in EET levels occurred in culture media, indicating both that cell associated EET concentrations quickly reach saturation and EET-hydrolyzing activity mostly effects extracellular EET signaling. In vivo, DRGs from sEH-deficient mice exhibited elevated 8,9-, 11,12- and 14,15-EET-levels. Interestingly, EET levels did not increase at the site of zymosan-induced inflammation. Cellular imaging experiments revealed direct calcium flux responses to 8,9-EET in a subpopulation of nociceptors. In addition, 8,9-EET sensitized AITC-induced calcium increases in DRG neurons and AITC-induced calcitonin gene related peptide (CGRP) release from sciatic nerve axons, indicating that 8,9-EET sensitizes TRPA1-expressing neurons, which are known to contribute to mechanical hyperalgesia. Supporting this, sEH-/- mice showed increased nociceptive responses to mechanical stimulation during zymosan-induced inflammation and 8,9-EET injection reduced mechanical thresholds in naive mice. Conclusion Our results show that the sEH can regulate mechanical hyperalgesia during inflammation by inactivating 8,9-EET, which sensitizes TRPA1-expressing nociceptors. Therefore we suggest that influencing the CYP450 pathway, which is actually highly considered to treat cardiovascular diseases, may cause pain side effects. PMID:21970373

  17. Pharmacokinetics: time-dependent changes--autoinduction of carbamazepine epoxidation

    SciTech Connect

    Bertilsson, L.; Tomson, T.; Tybring, G.

    1986-07-01

    Drugs labeled with stable isotopes have been useful to study time-dependent changes in kinetics. Early studies suggested that carbamazepine (CBZ) may induce its own metabolism, but this could not be proved until tetradeuterium-labeled CBZ (CBZ-D4) was synthesized and then given to patients. CBZ-D4 was administered to three children during long-term treatment of epilepsy with CBZ. After 17 to 32 days of treatment, the plasma clearance of CBZ-D4 was doubled, but during the next four months, there was no further increase, indicating that autoinduction was complete within one month. Two patients with chronic alcoholism were treated with CBZ for five days. Half of the first dose of 600 mg was comprised of CBZ-D4. The half-life of this CBZ-D4 dose in the two patients (20 and 26 hr, respectively) was similar to the post-steady-state half-life of CBZ (23 hr in both patients) measured later. A single dose of CBZ given one week after the last maintenance dose had a longer half-life (46 and 45 hr, respectively), which probably is close to the disposition of the drug before starting the treatment with CBZ. This shows that autoinduction of CBZ metabolism was completed during the very first doses of CBZ. Autoinduction also disappeared rapidly after stopping the treatment. We have shown that it is mainly the epoxide-diol pathway that is induced, both during autoinduction and after induction with other antiepileptic agents.

  18. Evaluation of fish models of soluble epoxide hydrolase inhibition.

    PubMed Central

    Newman, J W; Denton, D L; Morisseau, C; Koger, C S; Wheelock, C E; Hinton, D E; Hammock, B D

    2001-01-01

    Substituted ureas and carbamates are mechanistic inhibitors of the soluble epoxide hydrolase (sEH). We screened a set of chemicals containing these functionalities in larval fathead minnow (Pimphales promelas) and embryo/larval golden medaka (Oryzias latipes) models to evaluate the utility of these systems for investigating sEH inhibition in vivo. Both fathead minnow and medaka sEHs were functionally similar to the tested mammalian orthologs (murine and human) with respect to substrate hydrolysis and inhibitor susceptibility. Low lethality was observed in either larval or embryonic fish exposed to diuron [N-(3,4-dichlorophenyl), N'-dimethyl urea], desmethyl diuron [N-(3,4-dichlorophenyl), N'-methyl urea], or siduron [N-(1-methylcyclohexyl), N'-phenyl urea]. Dose-dependent inhibition of sEH was a sublethal effect of substituted urea exposure with the potency of siduron < desmethyl diuron = diuron, differing from the observed in vitro sEH inhibition potency of siduron > desmethyl diuron > diuron. Further, siduron exposure synergized the toxicity of trans-stilbene oxide in fathead minnows. Medaka embryos exposed to diuron, desmethyl diuron, or siduron displayed dose-dependent delays in hatch, and elevated concentrations of diuron and desmethyl diuron produced developmental toxicity. The dose-dependent toxicity and in vivo sEH inhibition correlated, suggesting a potential, albeit undefined, relationship between these factors. Additionally, the observed inversion of in vitro to in vivo potency suggests that these fish models may provide tools for investigating the in vivo stability of in vitro inhibitors while screening for untoward effects. PMID:11171526

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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.

  8. 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.

  9. 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.

  10. Asymmetric epoxidation of allylic alcohols catalyzed by vanadium-binaphthylbishydroxamic Acid complex.

    PubMed

    Noji, Masahiro; Kobayashi, Toshihiro; Uechi, Yuria; Kikuchi, Asami; Kondo, Hisako; Sugiyama, Shigeo; Ishii, Keitaro

    2015-03-20

    A vanadium-binaphthylbishydroxamic acid (BBHA) complex-catalyzed asymmetric epoxidation of allylic alcohols is described. The optically active binaphthyl-based ligands BBHA 2a and 2b were synthesized from (S)-1,1'-binaphthyl-2,2'-dicarboxylic acid and N-substituted-O-trimethylsilyl (TMS)-protected hydroxylamines via a one-pot, three-step procedure. The epoxidations of 2,3,3-trisubstituted allylic alcohols using the vanadium complex of 2a were easily performed in toluene with a TBHP water solution to afford (2R)-epoxy alcohols in good to excellent enantioselectivities. PMID:25714329

  11. The selection reaction of homogeneous catalyst in soy-epoxide hydroxylation

    NASA Astrophysics Data System (ADS)

    Elvistia Firdaus, Flora

    2014-04-01

    Hydroxylation reaction of soy-epoxide has resulted soy-polyol; a prepolymeric material for polyurethane. The conversion and selectivity of soy-epoxide butanol based to hydroxylation was found higher than soy-ethylene glycol (EG) based. These reactions were performed by sulfur acid which commonly known as homogeneous catalyst. Conversion and selectivity of homogeneous catalyst compared to bentonite; a heteregeneous catalyst was lower as in fact the mixtures were more viscous. The catalysis were significantly effected to cell morphology. Foams were conducted by heterogeneous catalyst resulted an irregular form of windows while homogeneous catalyst are more ordered.

  12. Synthesis of phytuberin. 4-endo-tet acid-catalyzed cyclization of alpha-hydroxy epoxides.

    PubMed

    Prangé, Thierry; Rodríguez, María S; Suárez, Ernesto

    2003-05-30

    The total synthesis of phytuberin, a phytoalexin of the Solanum genus, from (-)-alpha-santonin is reported. The key steps include (a) reductive cleavage of the C-O bond of the gamma-lactone with concomitant protection of the C1 double bond, (b) Sharpless stereocontrolled hydroxy-assisted epoxidation of allylic alcohol 6 and simultaneous deprotection of the C1 double bond, (c) a rare 4-endo-tet acid-catalyzed cyclization of an alpha-hydroxy epoxide, and (d) an unprecedented 4-exo selenocyclization of a homoallylic alcohol. PMID:12762747

  13. Ni(II) salts and 2-propanol effect catalytic reductive coupling of epoxides and alkynes.

    PubMed

    Beaver, Matthew G; Jamison, Timothy F

    2011-08-01

    A Ni-catalyzed reductive coupling of alkynes and epoxides using Ni(II) salts and simple alcohol reducing agents is described. Whereas previously reported conditions relied on Ni(cod)(2) and Et(3)B, this system has several advantages including the use of air-stable and inexpensive Ni(II) precatalysts (e.g., NiBr(2)·3H(2)O) as the source of Ni(0) and simple alcohols (e.g., 2-propanol) as the reducing agent. Deuterium-labeling experiments are consistent with oxidative addition of an epoxide C-O bond that occurs with inversion of configuration. PMID:21718038

  14. 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.

  15. Novel Finding of Widespread Occurrence and Accumulation of Bisphenol A Diglycidyl Ethers (BADGEs) and Novolac Glycidyl Ethers (NOGEs) in Marine Mammals from the United States Coastal Waters.

    PubMed

    Xue, Jingchuan; Kannan, Kurunthachalam

    2016-02-16

    Bisphenol A diglycidyl ether (BADGE)- and bisphenol F diglycidyl ether (BFDGE)-based epoxy resins have a broad range of applications, including serving as inner coatings of food and beverage cans and as protective coatings in marine construction. Prior to this study, no studies had examined the occurrence and bioaccumulation of BADGEs or BFDGEs in aquatic organisms. In this study, BADGE, BFDGE, and nine of their derivatives were determined in 121 tissue (liver, kidney, blubber, and brain) samples from eight species of marine mammals collected from the U.S. coastal waters of Florida, California, Washington, and Alaska. BADGE·2HCl was the predominant compound found in the majority (78.5%) of the marine mammal tissues analyzed, at concentrations of up to 2950 ng/g (wet weight (wt)) found in the liver of a sea otter from Kachemak Bay, Alaska. The measured concentrations of BADGE·2HCl in marine mammals were on the order of hundreds of nanograms per gram tissue, which are some of the highest concentrations ever reported for this compound in biota. Males contained greater concentrations of BADGE·2HCl than did females. BADGE·2HCl also was found in the brain tissues of sea otters. Trace levels of BADGE·2HCl were found in the livers of polar bears from Alaska, which suggested that BADGEs are widely distributed in the oceanic environment. PMID:26800265

  16. 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

  17. Preferential Glutathione Conjugation of a Reverse Diol Epoxide Compared with a Bay Region Diol Epoxide of Benzo[a]pyrene in Human Hepatocytes

    PubMed Central

    Upadhyaya, Pramod; Hochalter, J. Bradley; Balbo, Silvia; McIntee, Edward J.

    2010-01-01

    Many studies have examined the relationship between polymorphisms in glutathione S-transferase genes and cancer in people exposed to polycyclic aromatic hydrocarbons (PAH) such as benzo[a]pyrene (BaP), but the results to date have been modest. Missing from these studies has been an exploration of the formation of the appropriate glutathione conjugates in humans. We incubated human hepatocytes from 10 donors with racemic anti-BaP-7,8-diol-9,10-epoxide (BPDE), believed to be a major ultimate carcinogen of BaP, or with the noncarcinogenic reverse diol epoxide, racemic anti-BaP-9,10-diol-7,8-epoxide (rev-BPDE). Incubations were carried out for 12 or 24 h. We used high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry-selected reaction monitoring at m/z 464 → m/z 317 to analyze the incubation mixtures for the mercapturic acid products that would result from glutathione conjugation. The standard mercapturic acids were synthesized by reaction of BPDE or rev-BPDE with N-acetylcysteine. We obtained convincing evidence in human hepatocytes for mercapturic acid formation from rev-BPDE in all 10 samples, in amounts up to 17 pmol/ml. However, we could detect mercapturic acids from BPDE in only 1 of 10 samples (0.05 pmol/ml). Taken together with our similar previous results of analyses of phenanthrene metabolites in human hepatocytes and human urine, the results of this study indicate that conjugation of BPDE with glutathione is a minor pathway in humans, indicating that glutathione S-transferase genotyping is not an effective method for assessing risk of PAH-induced cancer in humans, at least with respect to the diol epoxide pathway of PAH carcinogenesis. PMID:20547966

  18. 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.

  19. 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.

  20. Volume shrinkage and rheological studies of epoxidised and unepoxidised poly(styrene-block-butadiene-block-styrene) triblock copolymer modified epoxy resin-diamino diphenyl methane nanostructured blend systems.

    PubMed

    George, Sajeev Martin; Puglia, Debora; Kenny, Josè M; Parameswaranpillai, Jyotishkumar; Vijayan P, Poornima; Pionteck, Jűrgen; Thomas, Sabu

    2015-05-21

    Styrene-block-butadiene-block-styrene (SBS) copolymers epoxidised at different epoxidation degrees were used as modifiers for diglycidyl ether of the bisphenol A-diamino diphenyl methane (DGEBA-DDM) system. Epoxy systems containing modified epoxidised styrene-block-butadiene-block-styrene (eSBS) triblock copolymer with compositions ranging from 0 to 30 wt% were prepared and the curing reaction was monitored in situ using rheometry and pressure-volume-temperature (PVT) analysis. By controlling the mole percent of epoxidation, we could generate vesicles, worm-like micelles and core-shell nanodomains. At the highest mole percent of epoxidation, the fraction of the epoxy miscible component in the triblock copolymer (epoxidised polybutadiene (PB)) was maximum. This gave rise to core-shell nanodomains having a size of 10-15 nm, in which the incompatible polystyrene (PS) becomes the core, the unepoxidised PB becomes the shell and the epoxidised PB interpenetrates with the epoxy phase. On the other hand, the low level of epoxidation gave rise to bigger domains having a size of ∼1 μm and the intermediate epoxidation level resulted in a worm-like structure. This investigation specifically focused on the importance of cure rheology on nanostructure formation, using rheometry. The reaction induced phase separation of the PS phase in the epoxy matrix was carefully explored through rheological measurements. PVT measurements during curing were carried out to understand the volume shrinkage of the blend, confirming that shrinkage behaviour is related to the block copolymer phase separation process during curing. The volume shrinkage was found to be maximum in the case of blends with unmodified SBS, where a heterogeneous morphology was observed, while a decrease in the shrinkage was evidenced in the case of SBS epoxidation. It could be explained by two effects: (1) solubility of the epoxidised block copolymer in the DGEBA leads to the formation of nanoscopic domains upon

  1. High-performance UV-curable epoxy resin-based microarray and microfluidic immunoassay devices.

    PubMed

    Yu, Ling; Liu, Yingshuai; Gan, Ye; Li, Chang Ming

    2009-06-15

    Immunoassay devices including microarray and microfluidic systems were fabricated with an UV-curable resin by a new economic approach, which can not only simply produce a 3-dimensional (3D) patterned structure, but also simultaneously introduce functional epoxide groups for efficient protein immobilization. The performance of the epoxy resin-based microarray was improved by optimization of printing buffer, probe concentration, and immobilization time, showing a detection dynamic range of 5 orders of magnitude and a limit of detection (LOD) of 10 pg mL(-1) for immunoglobulin G (IgG). The developed microfluidic immunoassay device demonstrates a LOD of 100 pg mL(-1) for IL-5 detection. The device can also be used to colorimetrically detect proteins via naked human eyes for immunoassays. This work provides a simple and inexpensive method to fabricate a sensitive immunoassay device, especially a 3D microfluidic system, which has great potential to develop a portable immunoassay device via human eye detection for point-of-care service and/or high throughput screening of infectious diseases. PMID:19346122

  2. 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.

  3. Preferential Glutathione Conjugation of a Reverse Diol Epoxide Compared to a Bay Region Diol Epoxide of Phenanthrene in Human Hepatocytes: Relevance to Molecular Epidemiology Studies of Glutathione-S-Transferase Polymorphisms and Cancer

    PubMed Central

    Hecht, Stephen S.; Berg, Jeannette Zinggeler; Hochalter, J. Bradley

    2009-01-01

    Bay region diol epoxides are recognized ultimate carcinogens of polycyclic aromatic hydrocarbons (PAH), and in vitro studies have demonstrated that they can be detoxified by conjugation with glutathione, leading to the widely investigated hypothesis that individuals with low activity forms of glutathione-S-transferases are at higher risk of PAH induced cancer, a hypothesis that has found at most weak support in molecular epidemiology studies. A weakness in this hypothesis was that the mercapturic acids resulting from conjugation of PAH bay region diol epoxides had never been identified in human urine. We recently analyzed smokers’ urine for mercapturic acids derived from phenanthrene, the simplest PAH with a bay region. The only phenanthrene diol epoxide-derived mercapturic acid in smokers’ urine was produced from the reverse diol epoxide, anti-phenanthrene-3,4-diol-1,2-epoxide (11), not the bay region diol epoxide, anti-phenanthrene-1,2-diol-3,4-epoxide (10), which does not support the hypothesis noted above. In this study, we extended these results by examining the conjugation of phenanthrene metabolites with glutathione in human hepatocytes. We identified the mercapturic acid N-acetyl-S-(r-4,t-2,3-trihydroxy-1,2,3,4-tetrahydro-c-1-phenanthryl)-L-cysteine (14a), (0.33–35.9 pmol/mL at 10 µM 8, 24h incubation, N = 10) in all incubations with phenanthrene-3,4-diol (8) and the corresponding diol epoxide 11, but no mercapturic acids were detected in incubations with phenanthrene-1,2-diol (7) and only trace amounts were observed in incubations with the corresponding bay region diol epoxide 10. Taken together with our previous results, these studies clearly demonstrate that glutathione conjugation of a reverse diol epoxide of phenanthrene is favored over conjugation of a bay region diol epoxide. Since reverse diol epoxides of PAH are generally weakly or non-mutagenic/carcinogenic, these results, if generalizable to other PAH, do not support the widely held

  4. Diastereoselective synthesis of CF3-substituted, epoxide-fused heterocycles with β-(trifluoromethyl)vinylsulfonium salts.

    PubMed

    Fritz, Sven P; West, Thomas H; McGarrigle, Eoghan M; Aggarwal, Varinder K

    2012-12-21

    CF(3)-substituted vinyl diphenylsulfonium triflate is an effective annulation reagent for the formation of α-CF(3) substituted, epoxide-fused heterocycles (pyrrolidines, piperidines, and tetrahydrofurans). This simple method affords a variety of valuable heterocyclic building blocks in a highly diastereoselective manner (dr >20:1). PMID:23231752

  5. Synthesis of an Epoxide Carbonylation Catalyst: Exploration of Contemporary Chemistry for Advanced Undergraduates

    ERIC Educational Resources Information Center

    Getzler, Yutan D. Y. L.; Schmidt, Joseph A. R.; Coates, Geoffrey W.

    2005-01-01

    A class of highly active, well-defined compounds for the catalytic carbonylation of epoxides and aziridines to beta-lactones and beta-lactams are introduced. The synthesis of one of the catalysts involves a simple imine condensation to form the ligand followed by air-sensitive metalation and salt metathesis steps.

  6. EPOXIDATION OF SMALL ORGANIC MOLECULES USING A SPINNING TUBE-IN-TUBE REACTOR

    EPA Science Inventory

    The commodity-scale epoxidation of several organic molecules has been carried out using a Spinning Tube-in-Tube (STTr) reactor (manufactured by Kreido Laboratories). This reactor, which embodies and facilitates the use of Green Chemistry principles and Process Intensification, a...

  7. Hydroxylation and Epoxidation of Fatty Acids by Bacillus megaterium ALA2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacillus megaterium ALA2 produces many new oxygenated fatty acids from linoleic acid. Strain ALA2 hydroxylated palmitic acid to omega-1, omega-2, and omega-3 hydroxy palmitate. Now we found that strain ALA2 also epoxidized linoleic acid to 12,13-epoxy-9(Z)-octadecenoic acid and 9,10-epoxy-12(Z)-oc...

  8. Deep eutectic solvents (DESs) are viable cosolvents for enzyme-catalyzed epoxide hydrolysis.

    PubMed

    Lindberg, Diana; de la Fuente Revenga, Mario; Widersten, Mikael

    2010-06-01

    A special group of ionic liquids, deep eutectic solvents (DESs) have been tested as cosolvents in enzyme-catalyzed hydrolysis of a chiral (1,2)-trans-2-methylstyrene oxide. The choline chloride:ethane diol (ET), choline chloride:glycerol (GLY) and choline:chloride:urea (REL) DESs were included in the reaction mixtures with epoxide and the potato epoxide hydrolase StEH1. The effect of the DESs on enzyme function was primarily elevations of K(M) (up to 20-fold) and with lesser effects on turnover numbers (twofold variation). The regioselectivity in hydrolysis of the (1R,2R)-2-trans-methylstyrene oxide was altered in the presence of GLY or ET to favor epoxide ring opening at the benzylic carbon (R=2.33), enhancing the regioselectivity observed in buffer-only systems (R=1.35). The DES solutions dissolved 1.5-fold higher epoxide concentrations as compared to phosphate buffer. The total conversion of high concentration (40 g/l) of (1S,2S)-MeSO was not negatively affected by addition of 40% GLY. PMID:20438773

  9. Thermal behavior of epoxidized cardanol diethyl phosphate as novel renewable plasticizer for poly(vinyl chloride)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A novel plasticizer, epoxidized cardanol diethyl phosphate (ECEP), based on cardanol was synthesized. Chemical structure of ECEP was characterized by fourier transform infrared (FTIR), 1H-nuclear magnetic resonance(1H NMR) and 13C-nuclear magnetic resonance(13C NMR) spectroscopy. Effects of ECEP sub...

  10. Catalyzed ring-opening polymerization of epoxidized soybean oil by hydrated and anhydrous fluoroantimonic acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ring-opening polymerization of epoxidized soybean oil (ESO) catalyzed by the super acid, fluroantimonic acid hexahydrate (HSbF6-6H2O), and the anhydrous form (HSbF6) in ethyl acetate was conducted in an effort to develop useful biodegradable polymers. The resulting polymerized ESO (SA-RPESO and SAA-...

  11. Lewis Acid Catalyzed Ring-opening Polymerization of Epoxidized Soybean Oil in Liquid Carbon Dioxide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ring-opening polymerization of epoxidized soybean oil (ESO) catalyzed by boron trifluoride diethyl etherate (BF3•OEt2), in liquid carbon dioxide, was conducted in an effort to develop useful biobased biodegradable polymers. The resulting polymers (RPESO) were characterized by FTIR spectroscopy, diff...

  12. Boron Trifluoride Catalized Ring-Opening Polymerization of Epoxidized Soybean Oil in Liquid Carbon Dioxide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Boron trifluoride diethyl etherate (BF3.OEt2) catalyzed ring-opening polymerization of epoxidized soybean oil (ESO), in liquid carbon dioxide, was conducted in an effort to develop useful biobased biodegradable polymers. The resulting polymers (RPESO) were characterized by FTIR spectroscopy, differ...

  13. Formation of furan fatty alkyl esters from their bis-epoxide fatty esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reactions of epoxidized alkyl soyate with four different alcohols: ethanol, isopropyl alcohol, 2-ethylhexanol, benzyl alcohol, in the presence of Bronsted acid catalyst, were investigated. Products that were not reported in prior studies of similar reactions were found. These were furan fatty acid a...

  14. EXPRESSION AND CHARACTERIZATION OF THE RECOMBINANT JUVENILE HORMONE EPOXIDE HYDROLASE (JHEH) FROM MANDUCA SEXTA. (R825433)

    EPA Science Inventory

    The cDNA of the microsomal Juvenile Hormone Epoxide Hydrolase (JHEH) from Manduca sexta was expressed in vitro in the baculovirus system. In insect cell culture, the recombinant enzyme (Ms-JHEH) was produced at a high level (100 fold over background EH catalytic activit...

  15. Ultrathin CuO nanorods: controllable synthesis and superior catalytic properties in styrene epoxidation.

    PubMed

    Jia, Wei; Liu, Yuxi; Hu, Pengfei; Yu, Rong; Wang, Yu; Ma, Lei; Wang, Dingsheng; Li, Yadong

    2015-05-25

    Ultrathin copper oxide (CuO) nanorods with diameters of ∼3.6 nm were obtained in one step using oleylamine (OAm) as both the solvent and the surface controller. The oriented attachment is responsible for the formation of the ultrathin CuO nanorods. Furthermore, this ultrathin nanostructure catalyst exhibited excellent activity and high styrene oxide yields in styrene epoxidation. PMID:25920405

  16. (Salen)Mn(III) Catalyzed Asymmetric Epoxidation Reactions by Hydrogen Peroxide in Water: A Green Protocol

    PubMed Central

    Ballistreri, Francesco Paolo; Gangemi, Chiara M. A.; Pappalardo, Andrea; Tomaselli, Gaetano A.; Toscano, Rosa Maria; Trusso Sfrazzetto, Giuseppe

    2016-01-01

    Enantioselective epoxidation reactions of some chosen reactive alkenes by a chiral Mn(III) salen catalyst were performed in H2O employing H2O2 as oxidant and diethyltetradecylamine N-oxide (AOE-14) as surfactant. This procedure represents an environmentally benign protocol which leads to e.e. values ranging from good to excellent (up to 95%). PMID:27420047

  17. Sultones and Sultines via a Julia–Kocienski Reaction of Epoxides

    PubMed Central

    Smith, Geoffrey M T; Burton, Paul M; Bray, Christopher D

    2015-01-01

    The development of the homologous Julia–Kocienski reaction has led to the discovery of two new reaction modes of epoxides with sulfones. These pathways allow rapid and direct access to a range of γ-sultones and γ-sultines. PMID:26503062

  18. FORMATION OF HEMOGLOBIN ADDUCTS OF ACRYLAMIDE AND ITS EPOXIDE METABOLITE GLYCIDAMIDE IN THE RAT

    EPA Science Inventory

    A method was developed for the determination of hemoglobin (Hb) adducts form by the neurotoxic agent acrylamide and its mutagenic epoxide metabolite glycidamide. he method was based on simultaneous measurements of the cysteine adducts formed by these two agents by means of gas ch...

  19. Differences in Catalytic Sites for CO Oxidation and Propylene Epoxidation on Au Nanoparticles

    SciTech Connect

    Lee, W.S.; Stach, E.; Zhang, R.; Akatay, M.C.; Baertsch, C.D.; Ribeiro, F.H.; Delgass, W.N.

    2011-08-29

    Sintering and increased Au loading of Au/TS-1 causes the rate of CO oxidation per mole of Au to increase, whereas that for epoxidation of propylene in O{sub 2} and H{sub 2} decreases. This opposite trend in rate behavior shows that the catalytic sites for the two reactions must be different.

  20. Graphene oxide as an acid catalyst for the room temperature ring opening of epoxides.

    PubMed

    Dhakshinamoorthy, Amarajothi; Alvaro, Mercedes; Concepción, Patricia; Fornés, Vicente; Garcia, Hermenegildo

    2012-06-01

    The minute amount of hydrogen sulfate groups introduced into the graphene oxide (GO) obtained by Hummers oxidation of graphite renders this material as a highly efficient, recyclable acid catalyst for the ring opening of epoxides with methanol and other primary alcohols as nucleophile and solvent. PMID:22534622

  1. Synthesis of epoxidized cardanol and its antioxidative properties for vegetable oils and biodiesel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A novel antioxidant epoxidized cardanol (ECD), derived from cardanol, was synthesized and characterized by FT-IR, 1H-NMR and 13C-NMR. Oxidative stability of ECD used in vegetable oils and biodiesel was evaluated by pressurized differential scanning calorimetry (PDSC) and the Rancimat method, respect...

  2. Indirubin 3'-Epoxide Induces Caspase-Independent Cell Death in Human Neuroblastoma.

    PubMed

    Kurita, Masahiro; Hanada, Satoshi; Ichimaru, Yoshimi; Saito, Hiroaki; Tabata, Keiichi; Asami, Satoru; Miyairi, Shinichi; Suzuki, Takashi

    2016-01-01

    Indirubin inhibits cyclin-dependent kinases by binding to their ATP-binding site, thereby exerting potent cytotoxicity on some tumor cells. We examined the anti-tumor effect of indirubin 3'-epoxide on human neuroblastoma cell lines (IMR-32, SK-N-SH, and NB-39). The results revealed potent cytotoxicity of indirubin 3'-epoxide against the IMR-32 (IC50: 0.16 µM) and SK-N-SH (IC50: 0.07 µM) cells. Furthermore, it also induced an increase of the sub-G1 population in the IMR-32 cells. Examination by Hoechst 33342 staining revealed apoptosis characterized by cell shrinkage, nuclear condensation and nuclear fragmentation in a concentration-dependent manner. Furthermore, annexin V-propidium iodide (PI) double-staining revealed an increase in the percentage of early apoptotic cells following treatment of the cells with indirubin 3'-epoxide without activation of caspases. In addition, significant decreases in the protein level of survivin and poly(ADP-ribose)polymerase (PARP), and increase in that of apoptosis-inducing factor (AIF) were found in the nuclei of the cells. These results suggest that indirubin 3'-epoxide induced caspase-independent apoptosis through mechanisms involving DNA fragmentation and inhibition of DNA repair. PMID:27251501

  3. Surface Tension Studies of Alkyl Esters and Epoxidized Alkyl Esters Relevant to Oleochemically Based Fuel Additives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report the surface tension of several epoxidized oleochemicals and their comparable fatty esters at temperatures between 25 and 60 deg C. Surface tensions of the olefins measured at 40 deg C range from 25.9 mN m-1, for isobutyl oleate, to 28.4 mN m-1 for methyl linoleate. The epoxy versions of ...

  4. Engineering of an epoxide hydrolase for efficient bioresolution of bulky pharmaco substrates

    PubMed Central

    Kong, Xu-Dong; Yuan, Shuguang; Li, Lin; Chen, She; Xu, Jian-He; Zhou, Jiahai

    2014-01-01

    Optically pure epoxides are essential chiral precursors for the production of (S)-propranolol, (S)-alprenolol, and other β-adrenergic receptor blocking drugs. Although the enzymatic production of these bulky epoxides has proven difficult, here we report a method to effectively improve the activity of BmEH, an epoxide hydrolase from Bacillus megaterium ECU1001 toward α-naphthyl glycidyl ether, the precursor of (S)-propranolol, by eliminating the steric hindrance near the potential product-release site. Using X-ray crystallography, mass spectrum, and molecular dynamics calculations, we have identified an active tunnel for substrate access and product release of this enzyme. The crystal structures revealed that there is an independent product-release site in BmEH that was not included in other reported epoxide hydrolase structures. By alanine scanning, two mutants, F128A and M145A, targeted to expand the potential product-release site displayed 42 and 25 times higher activities toward α-naphthyl glycidyl ether than the wild-type enzyme, respectively. These results show great promise for structure-based rational design in improving the catalytic efficiency of industrial enzymes for bulky substrates. PMID:25331869

  5. BENZO(A)PYRENE DIOL EPOXIDE I BINDS TO DNA AT REPLICATION FORKS (JOURNAL VERSION)

    EPA Science Inventory

    The distribution in replication forks of DNA lesions caused by the treatment of S phase calls with benzo(a)pyrene-diol-epoxide-1 (BPDE-1) was studied in synchronized C3H10T1/2 cells. Sites of carcinogen modification of DNA were identified by polyclonal rabbit antibodies that were...

  6. Epoxide hydrolase activities and epoxy fatty acids in the mosquito Culex quinquefasciatus

    PubMed Central

    Xu, Jiawen; Morisseau, Christophe; Yang, Jun; Mamatha, Dadala M.

    2015-01-01

    Culex mosquitoes have emerged as important model organisms for mosquito biology, and are disease vectors for multiple mosquito-borne pathogens, including West Nile virus. We characterized epoxide hydrolase activities in the mosquito Culex quinquefasciatus, which suggested multiple forms of epoxide hydrolases were present. We found EH activities on epoxy eicosatrienoic acids (EETs). EETs and other eicosanoids are well-established lipid signaling molecules in vertebrates. We showed EETs can be synthesized in vitro from arachidonic acids by mosquito lysate, and EETs were also detected in vivo both in larvae and adult mosquitoes by LC-MS/MS. The EH activities on EETs can be induced by blood feeding, and the highest activity was observed in the midgut of female mosquitoes. The enzyme activities on EETs can be inhibited by urea-based inhibitors designed for mammalian soluble epoxide hydrolases (sEH). The sEH inhibitors have been shown to play diverse biological roles in mammalian systems, and they can be useful tools to study the function of EETs in mosquitoes. Besides juvenile hormone metabolism and detoxification, insect epoxide hydrolases may also play a role in regulating lipid signaling molecules, such as EETs and other epoxy fatty acids, synthesized in vivo or obtained from blood feeding by female mosquitoes. PMID:25686802

  7. Formation of furan fatty alkyl esters from their bis-epoxide fatty esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reactions of epoxidized alkyl soyate with four different alcohols: ethanol, isopropyl alcohol, 2-ethylhexanol, and benzyl alcohol were investigated in the presence of Bronsted acid catalyst. Products not reported in prior studies of similar reactions were found. These were furan fatty acid alkyl est...

  8. INTERACTION OF BENZO(A)PYRENE DIOL EPOXIDE WITH SVAO MINICHROMOSOMES

    SciTech Connect

    Gamper, Howard B.; Yokota, Hisao A.; Bartholomew, James C.

    1980-03-01

    SV40 minichromosomes were reacted with (+)7{beta},8{alpha}-dihydroxy-9{alpha},10{alpha}-epoxy- 7,8,9,10-tetrahydrobenzo[a]pyrene (BaP diol epoxide). Low levels of modification (< 5 DNA adducts/minichromosome) did not detectably alter the structure of the minichromosomes but high levels (> 200 DNA adducts/minichromosome) led to extensive fragmentation. Relative to naked SV40 DNA BaP diol epoxide induced alkylation and strand scission of minichromosomal DNA was reduced or enhanced by factors of 1.5 and 2.0, respectively. The reduction in covalent binding was attributed to the presence of histones, which competed with DNA for the hydrocarbon and reduced the probability of BaP diol epoxide intercalation by tightening the helix. The enhancement of strand scission was probably due to the catalytic effect of histones on the rate of S-elimination at apurinic sites, although an altered adduct profile or the presence of a repair endonuclease were not excluded. Staphylococcal nuclease digestion indicated that BaP dial epoxide randomly alkylated the minichromosomal DNA. This is in contrast to studies with cellular chromatin where internucleosomal DNA was preferentially modified. Differences in the minichromosomal protein complement were responsible for this altered susceptibility.

  9. Predicting efficient C(60) epoxidation and viable multiple oxide formation by theoretical study

    PubMed

    Manoharan

    2000-02-25

    The epoxidation of C(60) by various oxidizing agents such as dimethyldioxirane (DMD), methyl(trifluoromethyl)dioxirane (MTMD), and bis(trifluoromethyl)dioxirane (BTMD) has been probed computationally by the AM1 method. The computations have revealed that for the reaction forming C(60)O through a concerted "spiro" transition state, the currently used DMD involves its HOMO lone-pair and the LUMO (pi) of fullerene in an inverse electron demand fashion. This is distinct from the DMD reaction with ethylene. On the other hand, the addition of CF(3) groups lowers the LUMO (peroxide sigma) of MTMD and BTMD by virtue of negative hyperconjugation; the oxidants can then attack the fullerene nucleophilically at an increased rate to the maximum extent. These estimations have thus established that the strong electrophilic oxidizing agents remarkably enhance the fullerene epoxidation. DMD further produces C(60)O(2) and C(60)O(3) via multiple epoxidations, as C(60)O might best be produced quantitatively by MTMD and BTMD. The regiochemistry of the multiple oxidation products in which the subsequent oxidations take place at the adjacent sites is consistent with the increased nucleophilicity of the nearest double bonds attached to the prevailing epoxide function. PMID:10814058

  10. Mononuclear Nonheme High-Spin Iron(III)-Acylperoxo Complexes in Olefin Epoxidation and Alkane Hydroxylation Reactions.

    PubMed

    Wang, Bin; Lee, Yong-Min; Clémancey, Martin; Seo, Mi Sook; Sarangi, Ritimukta; Latour, Jean-Marc; Nam, Wonwoo

    2016-02-24

    Mononuclear nonheme high-spin iron(III)-acylperoxo complexes bearing an N-methylated cyclam ligand were synthesized, spectroscopically characterized, and investigated in olefin epoxidation and alkane hydroxylation reactions. In the epoxidation of olefins, epoxides were yielded as the major products with high stereo-, chemo-, and enantioselectivities; cis- and trans-stilbenes were oxidized to cis- and trans-stilbene oxides, respectively. In the epoxidation of cyclohexene, cyclohexene oxide was formed as the major product with a kinetic isotope effect (KIE) value of 1.0, indicating that nonheme iron(III)-acylperoxo complexes prefer C═C epoxidation to allylic C-H bond activation. Olefin epoxidation by chiral iron(III)-acylperoxo complexes afforded epoxides with high enantioselectivity, suggesting that iron(III)-acylperoxo species, not high-valent iron-oxo species, are the epoxidizing agent. In alkane hydroxylation reactions, iron(III)-acylperoxo complexes hydroxylated C-H bonds as strong as those in cyclohexane at -40 °C, wherein (a) alcohols were yielded as the major products with high regio- and stereoselectivities, (b) activation of C-H bonds by the iron(III)-acylperoxo species was the rate-determining step with a large KIE value and good correlation between reaction rates and bond dissociation energies of alkanes, and (c) the oxygen atom in the alcohol product was from the iron(III)-acylperoxo species, not from molecular oxygen. In isotopically labeled water (H2(18)O) experiments, incorporation of (18)O from H2(18)O into oxygenated products was not observed in the epoxidation and hydroxylation reactions. On the basis of mechanistic studies, we conclude that mononuclear nonheme high-spin iron(III)-acylperoxo complexes are strong oxidants capable of oxygenating hydrocarbons prior to their conversion into iron-oxo species via O-O bond cleavage. PMID:26816269

  11. Biomimetic iron-catalyzed asymmetric epoxidation of aromatic alkenes by using hydrogen peroxide.

    PubMed

    Gelalcha, Feyissa Gadissa; Anilkumar, Gopinathan; Tse, Man Kin; Brückner, Angelika; Beller, Matthias

    2008-01-01

    A novel and general biomimetic non-heme Fe-catalyzed asymmetric epoxidation of aromatic alkenes by using hydrogen peroxide is reported herein. The catalyst consists of ferric chloride hexahydrate (FeCl(3)6 H(2)O), pyridine-2,6-dicarboxylic acid (H(2)(pydic)), and readily accessible chiral N-arenesulfonyl-N'-benzyl-substituted ethylenediamine ligands. The asymmetric epoxidation of styrenes with this system gave high conversions but poor enantiomeric excesses (ee), whereas larger alkenes gave high conversions and ee values. For the epoxidation of trans-stilbene (1 a), the ligands (S,S)-N-(4-toluenesulfonyl)-1,2-diphenylethylenediamine ((S,S)-4 a) and its N'-benzylated derivative ((S,S)-5 a) gave opposite enantiomers of trans-stilbene oxide, that is, (S,S)-2 a and (R,R)-2 a, respectively. The enantioselectivity of alkene epoxidation is controlled by steric and electronic factors, although steric effects are more dominant. Preliminary mechanistic studies suggest the in situ formation of several chiral Fe-complexes, such as [FeCl(L*)(2)(pydic)]HCl (L*=(S,S)-4 a or (S,S)-5 a in the catalyst mixture), which were identified by ESIMS. A UV/Vis study of the catalyst mixture, which consisted of FeCl(3)6 H(2)O, H(2)(pydic), and (S,S)-4 a, suggested the formation of a new species with an absorbance peak at lambda=465 nm upon treatment with hydrogen peroxide. With the aid of two independent spin traps, we could confirm by EPR spectroscopy that the reaction proceeds via radical intermediates. Kinetic studies with deuterated styrenes showed inverse secondary kinetic isotope effects, with values of k(H)/k(D)=0.93 for the beta carbon and k(H)/k(D)=0.97 for the alpha carbon, which suggested an unsymmetrical transition state with stepwise O transfer. Competitive epoxidation of para-substituted styrenes revealed a linear dual-parameter Hammett plot with a slope of 1.00. Under standard conditions, epoxidation of 1 a in the presence of ten equivalents of H(2) (18)O resulted in an absence

  12. Regioselective Isomerization of 2,3-Disubstituted Epoxides to Ketones: An Alternative to the Wacker Oxidation of Internal Alkenes.

    PubMed

    Lamb, Jessica R; Mulzer, Michael; LaPointe, Anne M; Coates, Geoffrey W

    2015-12-01

    We report an alternative pathway to the Wacker oxidation of internal olefins involving epoxidation of trans-alkenes followed by a mild and highly regioselective isomerization to give the major ketone isomers in 66-98% yield. Preliminary kinetics and isotope labeling studies suggest epoxide ring opening as the turnover limiting step in our proposed mechanism. A similar catalytic system was applied to the kinetic resolution of select trans-epoxides to give synthetically useful selectivity factors of 17-23 for benzyl-substituted substrates. PMID:26522052

  13. 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.

  14. Dysregulation of Soluble Epoxide Hydrolase and Lipidomic Profiles in Anorexia Nervosa

    PubMed Central

    Shih, Pei-an Betty; Yang, Jun; Morisseau, Christophe; German, J. Bruce; Van Zeeland, Ashley; Armando, Aaron M.; Quehenberger, Oswald; Bergen, Andrew W.; Magistretti, Pierre; Berrettini, Wade; Halmi, Katherine Ann; Schork, Nicholas; Hammock, Bruce D.; Kaye, Walter

    2015-01-01

    Individuals with anorexia nervosa (AN) restrict eating and become emaciated. AN tend to have an aversion to foods rich in fat. Because Epoxide Hydrolase 2 (EPHX2) was identified as a novel AN susceptibility gene, and because its protein product, soluble epoxide hydrolase (sEH), converts bioactive epoxides of polyunsaturated fatty acid (PUFA) to the corresponding diols, lipidomic and metabolomic targets of EPHX2 were assessed to evaluate the biological functions of EPHX2 and their role in AN. Epoxide substrates of sEH and associated oxylipins were measured in ill AN, recovered AN, and gender- and race-matched controls. PUFA and oxylipin markers were tested as potential biomarkers for AN. Oxylipin ratios were calculated as proxy markers of in vivo sEH activity. Several free- and total PUFAs were associated with AN diagnosis and with AN recovery. AN displayed elevated n-3 PUFAs and may differ from controls in PUFA elongation and desaturation processes. Cytochrome P450 pathway oxylipins from arachidonic acid, linoleic acid, alpha-linolenic acid, and docosahexaenoic acid PUFAs are associated with AN diagnosis. The diol:epoxide ratios suggest the sEH activity is higher in AN compared to controls. Multivariate analysis illustrates normalization of lipidomic profiles in recovered ANs. EPHX2 influences AN risk through in vivo interaction with dietary PUFAs. PUFA composition and concentrations as well as sEH activity may contribute to the pathogenesis and prognosis of AN. Our data support the involvement of EPHX2-associated lipidomic and oxylipin dysregulations in AN, and reveal their potential as biomarkers to assess responsiveness to future intervention or treatment. PMID:25824304

  15. Discovery of a Novel Microsomal Epoxide Hydrolase-Catalyzed Hydration of a Spiro Oxetane.

    PubMed

    Li, Xue-Qing; Hayes, Martin A; Grönberg, Gunnar; Berggren, Kristina; Castagnoli, Neal; Weidolf, Lars

    2016-08-01

    Oxetane moieties are increasingly being used by the pharmaceutical industry as building blocks in drug candidates because of their pronounced ability to improve physicochemical parameters and metabolic stability of drug candidates. The enzymes that catalyze the biotransformation of the oxetane moiety are, however, not well studied. The in vitro metabolism of a spiro oxetane-containing compound AZD1979 [(3-(4-(2-oxa-6-azaspiro[3.3]heptan-6-ylmethyl)phenoxy)azetidin-1-yl)(5-(4-ethoxyphenyl)-1,3,4-oxadiazol-2-yl)methanone] was studied and one of its metabolites, M1, attracted our interest because its formation was NAD(P)H independent. The focus of this work was to elucidate the structure of M1 and to understand the mechanism(s) of its formation. We established that M1 was formed via hydration and ring opening of the oxetanyl moiety of AZD1979. Incubations of AZD1979 using various human liver subcellular fractions revealed that the hydration reaction leading to M1 occurred mainly in the microsomal fraction. The underlying mechanism as a hydration, rather than an oxidation reaction, was supported by the incorporation of (18)O from H2 (18)O into M1. Enzyme kinetics were performed probing the formation of M1 in human liver microsomes. The formation of M1 was substantially inhibited by progabide, a microsomal epoxide hydrolase inhibitor, but not by trans-4-[4-(1-adamantylcarbamoylamino)cyclohexyloxy]benzoic acid, a soluble epoxide hydrolase inhibitor. On the basis of these results, we propose that microsomal epoxide hydrolase catalyzes the formation of M1. The substrate specificity of microsomal epoxide hydrolase should therefore be expanded to include not only epoxides but also the oxetanyl ring system present in AZD1979. PMID:27256986

  16. Reusable manganese compounds containing pyrazole-based ligands for olefin epoxidation reactions.

    PubMed

    Manrique, Ester; Poater, Albert; Fontrodona, Xavier; Solà, Miquel; Rodríguez, Montserrat; Romero, Isabel

    2015-10-28

    We describe the synthesis of new manganese(ii) and manganese(iii) complexes containing the bidentate ligands 2-(3-pyrazolyl)pyridine, pypz-H, and 3(5)-(2-hydroxyphenyl)pyrazole, HOphpz-H, with formula [MnX2(pypz-H)2] (X = Cl(-), 1, CF3SO3(-), 2, OAc(-), 3 or NO3(-) (4)), [MnCl2(pypz-H)(H2O)2], 5, or [MnCl(Ophpz-H)2], 6. All the complexes have been characterized through analytical, spectroscopic and electrochemical techniques. Single X-ray structure analysis revealed a six-coordinated Mn(ii) ion in complexes 1-5, and a five-coordinated Mn(iii) ion in complex 6. Compound 5 is the first co-crystal of Mn(ii) containing Cl and H2O ligands together with bidentate nitrogen ligands. The catalytic activity of complexes 1-6 has been tested with regard to the epoxidation of styrene and, in the case of 1, 5 and 6, other alkenes have been epoxidized using peracetic acid as oxidant in different media, among which glycerol, a green solvent never used in epoxidation reactions using peracetic acid as oxidant. The catalysts show moderate to high conversions and selectivities towards the corresponding epoxides. For complexes 1, 5 and 6, a certain degree of cis→trans isomerization is observed in the case of cis-β-methylstyrene. These observations have been explained through computational calculations. The reutilization of catalysts 1 and 6 for the epoxidation of alkenes has been evaluated in [bmim] : acetonitrile mixture (bmim = 1-butyl-3-methylimidazolium), allowing the effective recyclability of the catalytic system and keeping high conversion and selectivity values up to 12 successive runs, in all cases. PMID:26389716

  17. Titania-silica mixed oxides. II. Catalytic behaviour in olefin epoxidation

    SciTech Connect

    Hutter, R.; Mallat, T.; Baiker, A.

    1995-04-15

    Various titania-silica aerogels prepared by an alkoxide-sol-gel route have been tested in the epoxidation of bulky olefins using cumene hydroperoxide as oxidant. The drying method, the titanium content between 2 and 20 wt%, and the calcination temperature between 473 and 1073 K were the most important preparation parameters, influencing the catalytic behaviour of the aerogels. The aerogels dried by semicontinuous extraction with supercritical CO{sub 2} at low temperature (LT aerogel) were found to be much more efficient epoxidation catalysts than aerogels prepared by high-temperature supercritical drying and conventionally dried xerogels. The reaction rate of cyclohexene epoxidation over LT aerogels increased monotonically with increasing Ti content. In the range of 333-363 K the catalysts containing 20 wt% TiO{sub 2} (20LT) showed high activity and selectivity (79-93% to peroxide and 87-100% to epoxide) in the oxidation of various cyclic olefins, including cyclododecene, norbornene, cyclohexene, and limonene. Catalytic experiments, FTIR, and UV-vis spectroscopy indicated that the LT aerogels consist of two different types of active species: titanium well-dispersed in the silica matrix and titania nanodomains. The key factors determining the activity and selectivity of sol-gel titania-silica catalysts are the morphology (surface area and pore size) and the relative proportions of Ti-O-Si and Ti-O-Ti structural parts. A comparative study of the epoxidation of cyclohexene, cyclododecene, and norbornene over structurally different titania-silica catalysts, indicates that 20LT shows better catalytic behaviour in these reactions than Ti zeolites and silica-supported titania. 46 refs., 12 figs., 3 tabs.

  18. In Silico Prediction of Cytochrome P450-Mediated Biotransformations of Xenobiotics: A Case Study of Epoxidation.

    PubMed

    Zhang, Jing; Ji, Li; Liu, Weiping

    2015-08-17

    Predicting the biotransformation of xenobiotics is important in toxicology; however, as more compounds are synthesized than can be investigated experimentally, powerful computational methods are urgently needed to prescreen potentially useful candidates. Cytochrome P450 enzymes (P450s) are the major enzymes involved in xenobiotic metabolism, and many substances are bioactivated by P450s to form active compounds. An example is the conversion of olefinic substrates to epoxides, which are intermediates in the metabolic activation of many known or suspected carcinogens. We have calculated the activation energies for epoxidation by the active species of P450 enzymes (an iron-oxo porphyrin cation radical oxidant, compound I) for a diverse set of 36 olefinic substrates with state-of-the-art density functional theory (DFT) methods. Activation energies can be estimated by the computationally less demanding method of calculating the ionization potentials of the substrates, which provides a useful and simple predictive model based on the reaction mechanism; however, the preclassification of these diverse substrates into weakly polar and strongly polar groups is a prerequisite for the construction of specific predictive models with good predictability for P450 epoxidation. This approach has been supported by both internal and external validations. Furthermore, the relation between the activation energies for the regioselective epoxidation and hydroxylation reactions of P450s and experimental data has been investigated. The results show that the computational method used in this work, single-point energy calculations with the B3LYP functional including zero-point energy and solvation and dispersion corrections based on B3LYP-optimized geometries, performs well in reproducing the experimental trends of the epoxidation and hydroxylation reactions. PMID:26200167

  19. Dysregulation of soluble epoxide hydrolase and lipidomic profiles in anorexia nervosa.

    PubMed

    Shih, P B; Yang, J; Morisseau, C; German, J B; Zeeland, A A Scott-Van; Armando, A M; Quehenberger, O; Bergen, A W; Magistretti, P; Berrettini, W; Halmi, K A; Schork, N; Hammock, B D; Kaye, W

    2016-04-01

    Individuals with anorexia nervosa (AN) restrict eating and become emaciated. They tend to have an aversion to foods rich in fat. Because epoxide hydrolase 2 (EPHX2) was identified as a novel AN susceptibility gene, and because its protein product, soluble epoxide hydrolase (sEH), converts bioactive epoxides of polyunsaturated fatty acid (PUFA) to the corresponding diols, lipidomic and metabolomic targets of EPHX2 were assessed to evaluate the biological functions of EPHX2 and their role in AN. Epoxide substrates of sEH and associated oxylipins were measured in ill AN, recovered AN and gender- and race-matched controls. PUFA and oxylipin markers were tested as potential biomarkers for AN. Oxylipin ratios were calculated as proxy markers of in vivo sEH activity. Several free- and total PUFAs were associated with AN diagnosis and with AN recovery. AN displayed elevated n-3 PUFAs and may differ from controls in PUFA elongation and desaturation processes. Cytochrome P450 pathway oxylipins from arachidonic acid, linoleic acid, alpha-linolenic acid and docosahexaenoic acid PUFAs are associated with AN diagnosis. The diol:epoxide ratios suggest the sEH activity is higher in AN compared with controls. Multivariate analysis illustrates normalization of lipidomic profiles in recovered ANs. EPHX2 influences AN risk through in vivo interaction with dietary PUFAs. PUFA composition and concentrations as well as sEH activity may contribute to the pathogenesis and prognosis of AN. Our data support the involvement of EPHX2-associated lipidomic and oxylipin dysregulations in AN, and reveal their potential as biomarkers to assess responsiveness to future intervention or treatment. PMID:25824304

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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)...

  8. 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.

  9. 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.

  10. 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.

  11. Epoxide pathways improve model predictions of isoprene markers and reveal key role of acidity in aerosol formation

    EPA Science Inventory

    Isoprene significantly contributes to organic aerosol in the southeastern United States where biogenic hydrocarbons mix with anthropogenic emissions. In this work, the Community Multiscale Air Quality model is updated to predict isoprene aerosol from epoxides produced under both ...

  12. Isolation of β-Cryptoxanthin-epoxides, Precursors of Cryptocapsin and 3'-Deoxycapsanthin, from Red Mamey (Pouteria sapota).

    PubMed

    Turcsi, Erika; Murillo, Enrique; Kurtán, Tibor; Szappanos, Ádám; Illyés, Tünde-Zita; Gulyás-Fekete, Gergely; Agócs, Attila; Avar, Péter; Deli, József

    2015-07-01

    From an extract of red mamey (Pouteria sapota) β-cryptoxanthin-5,6-epoxide, β-cryptoxanthin-5',6'-epoxide, 3'-deoxycapsanthin, and cryptocapsin were isolated and characterized by UV-vis spectroscopy, electronic circular dichroism (ECD), nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry (MS). Epoxidation of β-cryptoxanthin delivered the β-(5'R,6'S)- and (5'S,6'R)-cryptoxanthin-5',6'-epoxides, which were identified by HPLC-ECD analysis. These carotenoids among others are quite common in the fruits of Central America, and as they are natural provitamins A, they should play an important role in the diet of the mostly vitamin A deficient population of this region. PMID:26057604

  13. 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.

  14. 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.

  15. Stress corrosion of fiberglass-reinforced (FRP) composites

    SciTech Connect

    Sapalidis, S.N.; Hogg, P.J.; Kelley, D.H.; Youd, S.J.

    1997-12-01

    The stress corrosion characteristics of uniaxial glass fiber reinforced thermosetting resin composites have been examined in Hydrochloric acid at room temperature and 80 C. A simple technique based on linear elastic fracture mechanisms (LEFM) is presented for characterizing crack growth in these materials subjected to hostile acidic environments. The environmental stress corrosion cracking is investigated both for different types of resin and different types of glass fiber reinforcements. Two matrices were used: Bis-A epoxy vinyl ester resin (based on Bisphenol-A epoxy resin) and novolac epoxy vinyl ester resin (based on epoxidized novolac resin). Two glass fiber types were employed: standard E-glass fiber and R, a special type of E-glass with superior acid resistance. Model experiments using a modified double cantilever beam test with static loading have been carried out on unidirectional composite specimens in 1M Hydrochloric acid solution at room temperature and 80 C. The rate of rack growth in the specimens depends on the applied stress, the temperature and the environment. Consequently, the lifetime of a component or structure made from GRP, subjected to stress corrosion conditions, could be predicted provided the dependence of crack growth rate on stress intensity at the crack tip is known. Scanning electron microscopy studies of the specimen fracture surfaces have identified the characteristic failure mechanisms. The most thing findings of this work is that the selection of epoxy vinyl ester resins reinforced with R fiber exhibited superior resistance to crack growth at 80 C compared to similar E-glass reinforced composites at room temperatures.

  16. 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.

  17. 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...

  18. 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

  19. 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.

  20. 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.

  1. Synthesis of beta-lactones by the regioselective, cobalt and Lewis acid catalyzed carbonylation of simple and functionalized epoxides.

    PubMed

    Lee, J T; Thomas, P J; Alper, H

    2001-08-10

    The PPNCo(CO)(4) and BF(3) x Et(2)O catalyzed carbonylation of simple and functionalized epoxides in DME gives the corresponding beta-lactones regioselectively in good to high yields. The carbonylation occurred selectively at the unsubstituted C-O bond of the epoxide ring, and this reaction tolerates various functional groups such as alkenyl, halide, hydroxy, and alkyl ether. PMID:11485465

  2. Nazarov cyclization of divinyl and arylvinyl epoxides: application in the synthesis of resveratrol-based natural products.

    PubMed

    Sudhakar, Gangarajula; Satish, Kovela

    2015-04-20

    New variation in the Nazarov cyclization has been developed by preparing divinyl and arylvinyl epoxides as pentadienyl cation precursors for the first time. Highly substituted cyclopentadienes, hydrindienes, and indenes were synthesized to demonstrate the compatibility of this reaction with substrates bearing a variety of substitutions and having different types of epoxides. Application of this method in the synthesis of resveratrol-based natural products was also demonstrated. PMID:25760544

  3. A New Biocatalyst for Production of Optically Pure Aryl Epoxides by Styrene Monooxygenase from Pseudomonas fluorescens ST

    PubMed Central

    Di Gennaro, Patrizia; Colmegna, Andrea; Galli, Enrica; Sello, Guido; Pelizzoni, Francesca; Bestetti, Giuseppina

    1999-01-01

    We developed a biocatalyst by cloning the styrene monooxygenase genes (styA and styB) from Pseudomonas fluorescens ST responsible for the oxidation of styrene to its corresponding epoxide. Recombinant Escherichia coli was able to oxidize different aryl vinyl and aryl ethenyl compounds to their corresponding optically pure epoxides. The results of bioconversions indicate the broad substrate preference of styrene monooxygenase and its potential for the production of several fine chemicals. PMID:10347083

  4. In Vivo Anti-Tumor Activity and Toxicological Evaluations of Perillaldehyde 8,9-Epoxide, a Derivative of Perillyl Alcohol

    PubMed Central

    Andrade, Luciana Nalone; Amaral, Ricardo Guimarães; Dória, Grace Anne Azevedo; Fonseca, Cecília Santos; da Silva, Tayane Kayane Mariano; Albuquerque Júnior, Ricardo Luiz Cavalcante; Thomazzi, Sara Maria; do Nascimento, Lázaro Gomes; Carvalho, Adriana Andrade; de Sousa, Damião Pergentino

    2016-01-01

    Recent studies have revealed the high cytotoxicity of p-menthane derivatives against human tumor cells. In this study, the substance perillaldehyde 8,9-epoxide, a p-menthane class derivative obtained from (S)-(−)-perillyl alcohol, was selected in order to assess antitumor activity against experimental sarcoma 180 tumors. Toxicological effects related to the liver, spleen, kidneys and hematology were evaluated in mice submitted to treatment. The tumor growth inhibition rate was 38.4%, 58.7%, 35.3%, 45.4% and 68.1% at doses of 100 and 200 mg/kg/day for perillaldehyde 8,9-epoxide, perillyl alcohol and 25 mg/kg/day for 5-FU intraperitoneal treatments, respectively. No toxicologically significant effect was found in liver and kidney parameters analyzed in Sarcoma 180-inoculated mice treated with perillaldehyde 8,9-epoxide. Histopathological analyses of the liver, spleen, and kidneys were free from any morphological changes in the organs of the animals treated with perillaldehyde 8,9-epoxide. In conclusion, the data suggest that perillaldehyde 8,9-epoxide possesses significant antitumor activity without systemic toxicity for the tested parameters. By comparison, there was no statistical difference for the antitumor activity between perillaldehyde 8,9-epoxide and perillyl alcohol. PMID:26742032

  5. Synthetic reactions with rare taccalonolides reveal the value of C-22,23 epoxidation for microtubule stabilizing potency.

    PubMed

    Peng, Jiangnan; Risinger, April L; Li, Jing; Mooberry, Susan L

    2014-07-24

    The taccalonolides are microtubule stabilizers isolated from plants of the genus Tacca. Taccalonolide AF is 231 times more potent than the major metabolite taccalonolide A and differs only by the oxidation of the C-22,23 double bond in A to an epoxy group in AF. In the current study, 10 other rare natural taccalonolides were epoxidized and in each case epoxidation improved potency. The epoxidation products of taccalonolide T and AI were the most potent, with IC50 values of 0.43 and 0.88 nM, respectively. These potent taccalonolides retained microtubule stabilizing effects, and T-epoxide demonstrated antitumor effects in a xenograft model of breast cancer. Additional reactions demonstrated that reduction of the C-6 ketone resulted in an inactive taccalonolide and that C-22,23 epoxidation restored its activity. These studies confirm the value of C-22,23 epoxidation as an effective strategy for increasing the potency of a wide range of structurally diverse taccalonolide microtubule stabilizers. PMID:24959756

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. From epoxidized linseed oil to bioresin: an overall approach of epoxy/anhydride cross-linking.

    PubMed

    Pin, Jean-Mathieu; Sbirrazzuoli, Nicolas; Mija, Alice

    2015-04-13

    Biorenewable resources can be used as green monomers to design tailored structures for formulations that can play an important role as functional materials. The choice of optimal structures depends on the targeted properties and applications. This work focuses on the elaboration of biobased materials with toughened mechanical properties based on epoxidized linseed oil. This result was obtained by an overall approach of cross-linking process, that is, starting with the optimal choice of hardeners and finally favoring the side reactions of polymerization. Therefore, the anionic alternating copolymerization of epoxide with mono- and dianhydrides was investigated to tailor the parameters that led to maximal conversions and properties. The obtained highly cross-linked networks perform well, as demonstrated by good impact strengths, high glass transition temperatures, and excellent thermal stability, which opens up the possibility of using these emergent materials for industrial applications. PMID:25754910

  11. Controlling Catalytic Selectivity via Adsorbate Orientation on the Surface: From Furfural Deoxygenation to Reactions of Epoxides.

    PubMed

    Pang, Simon H; Medlin, J Will

    2015-04-16

    Specificity to desired reaction products is the key challenge in designing solid catalysts for reactions involving addition or removal of oxygen to/from organic reactants. This challenge is especially acute for reactions involving multifunctional compounds such as biomass-derived aromatic molecules (e.g., furfural) and functional epoxides (e.g., 1-epoxy-3-butene). Recent surface-level studies have shown that there is a relationship between adsorbate surface orientation and reaction selectivity in the hydrogenation pathways of aromatic oxygenates and the ring-opening or ring-closing pathways of epoxides. Control of the orientation of reaction intermediates on catalytic surfaces by modifying the surface or near-surface environment has been shown to be a promising method of affecting catalytic selectivity for reactions of multifunctional molecules. In this Perspective, we review recent model studies aimed at understanding the surface chemistry for these reactions and studies that utilize this insight to rationally design supported catalysts. PMID:26263134

  12. Synthesis, characterization and catalytic activities towards epoxidation of olefins of dinuclear copper(II) complexes

    NASA Astrophysics Data System (ADS)

    Halder, Shibashis; Mukherjee, Aparajita; Ghosh, Koushik; Dey, Sudipto; Nandi, Mahasweta; Roy, Partha

    2015-12-01

    Two copper(II) complexes, [Cu2(L1)Cl3].2H2O (1) and [Cu2(L2)(N3)Cl2] (2) where HL1 = 4-methyl-2,6-bis((2-morpholinoethylimino)methyl)phenol and HL2 = 4-methyl-2,6-bis((3-morpholinopropylimino)methyl)phenol have been synthesized and characterized by elemental analysis, various spectroscopic methods, TGA and single crystal X-ray diffraction analysis. Single crystal X-ray diffraction analysis reveals that in both the complexes, two copper atoms are linked by phenoxo oxygen atom and a bridging ligand, namely chloride and azide, respectively. These complexes have been used as catalyst for the epoxidation of cyclohexene, styrene, α-methyl styrene, trans-stilbene and norbornene using tert-butyl hydroperoxide as the oxidant in acetonitrile under mild conditions. All of the substrates undergo conversion to produce respective epoxide as the major product.

  13. Block Copolymerization of Lactide and an Epoxide Facilitated by a Redox Switchable Iron-Based Catalyst.

    PubMed

    Biernesser, Ashley B; Delle Chiaie, Kayla R; Curley, Julia B; Byers, Jeffery A

    2016-04-18

    A cationic iron(III) complex was active for the polymerization of various epoxides, whereas the analogous neutral iron(II) complex was inactive. Cyclohexene oxide polymerization could be "switched off" upon in situ reduction of the iron(III) catalyst and "switched on" upon in situ oxidation, which is orthogonal to what was observed previously for lactide polymerization. Conducting copolymerization reactions in the presence of both monomers resulted in block copolymers whose identity can be controlled by the oxidation state of the catalyst: selective lactide polymerization was observed in the iron(II) oxidation state and selective epoxide polymerization was observed in the iron(III) oxidation state. Evidence for the formation of block copolymers was obtained from solubility differences, GPC, and DOSY-NMR studies. PMID:26991820

  14. 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...

  15. Direct Epoxidation of Propylene over Stabilized Cu+ Surface Sites on Ti Modified Cu2O

    SciTech Connect

    Yang, X.; Kattel, S.; Xiong, K.; Mudiyanselage, K.; Rykov, S.; Senanayake, S. D.; Rodriguez, J. A.; Liu, P.; Stacchiola, D. J.; Chen, J. G.

    2015-07-17

    Direct propylene epoxidation by O2 is a challenging reaction because of the strong tendency for complete combustion. Results from the current study demonstrate the feasibility to tune the epoxidation selectivity by generating highly dispersed and stabilized Cu+ active sites in a TiCuOx mixed oxide. The TiCuOx surface anchors the key surface intermediate, oxametallacycle, leading to higher selectivity for epoxidation of propylene.

  16. Cloning and characterization of an epoxide hydrolase from Cupriavidus metallidurans-CH34.

    PubMed

    Kumar, Ranjai; Wani, Shadil Ibrahim; Chauhan, Nar Singh; Sharma, Rakesh; Sareen, Dipti

    2011-09-01

    A putative epoxide hydrolase-encoding gene was identified from the genome sequence of Cupriavidus metallidurans CH34. The gene was cloned and overexpressed in Escherichia coli with His(6)-tag at its N-terminus. The epoxide hydrolase (CMEH) was purified to near homogeneity and was found to be a homodimer, with subunit molecular weight of 36 kDa. The CMEH had broad substrate specificity as it could hydrolyze 13 epoxides, out of 15 substrates tested. CMEH had high specific activity with 1,2-epoxyoctane, 1,2-epoxyhexane, styrene oxide (SO) and was also found to be active with meso-epoxides. The enzyme had optimum pH and temperature of 7.5 and 37°C respectively, with racemic SO. Biotransformation of 80 mM SO with recombinant whole E. coli cells expressing CMEH led to 56% ee(P) of (R)-diol with 77.23% conversion in 30 min. The enzyme could hydrolyze (R)-SO, ∼2-fold faster than (S)-SO, though it accepted both (R)- and (S)-SO with similar affinity as K(m)(R) and K(m)(S) of CMEH were 2.05±0.42 and 2.11±0.16 mM, respectively. However, the k(cat)(R) and k(cat)(S) for the two enantiomers of SO were 4.80 and 3.34 s(-1), respectively. The wide substrate spectrum exhibited by CMEH combined with the fast conversion rate makes it a robust biocatalyst for industrial use. Regioselectivity studies with enantiopure (R)- and (S)-SO revealed that with slightly altered regioselectivity, CMEH has a high potential to synthesize an enantiopure (R)-PED, through an enantioconvergent hydrolytic process. PMID:21515382

  17. Potent antimalarial 1,2,4-trioxanes through perhydrolysis of epoxides.

    PubMed

    Hao, Hong-Dong; Wittlin, Sergio; Wu, Yikang

    2013-06-01

    Perhydrolysis of a sterically congested multifunctional epoxide was achieved in ethereal H2O2 with the aid of a recently developed Mo catalyst. The resulting hydroperoxide cyclized to give a 1,2,4-trioxane, which could be readily elaborated into qinghaosu and a range of novel analogues. Some of the compounds with two such trioxane moieties showed in vitro antimalarial activity comparable to or even better than that of artesunate or chloroquine. PMID:23576327

  18. Monolithic Nickel (II) Oxide Aerogels Using an Organic Epoxide: The Importance of the Counter Ion

    SciTech Connect

    Gash, A E; Satcher, J H; Simpson, R L

    2004-01-13

    The synthesis and characterization of nickel (II) oxide aerogel materials prepared using the epoxide addition method is described. The addition of the organic epoxide propylene oxide to an ethanolic solution of NiCl{sub 2} 6H{sub 2}O resulted in the formation of an opaque light green monolithic gel and subsequent drying with supercritical CO{sub 2} gave a monolithic aerogel material of the same color. This material has been characterized using powder X-ray diffraction, electron microscopy, elemental analysis, and nitrogen adsorption/desorption analysis. The results indicate that the nickel (II) oxide aerogel has very low bulk density (98 kg/m{sup 3} ({approx}98 %porous)), high surface area (413 m{sup 2}/g), and has a particulate-type aerogel microstructure made up of very fine spherical particles with an open porous network. By comparison, a precipitate of Ni{sub 3}(NO{sub 3}){sub 2}(OH){sub 4} is obtained when the same preparation is attempted with the common Ni(NO{sub 3}){sub 2} 6H{sub 2}O salt as the precursor. The implications of the difference of reactivity of the two different precursors are discussed in the context of the mechanism of gel formation via the epoxide addition method. The synthesis of nickel (II) oxide aerogel, using the epoxide addition method, is especially unique in our experience. It is our first example of the successful preparation of a metal oxide aerogel using a metal divalent metal ion and may have implications for the application of this method to the preparation of aerogels or nanoparticles of other divalent metal oxides. To our knowledge this is the first report of a monolithic pure nickel (II) oxide aerogel materials.

  19. A stable epoxide as a potential endogenous estrogen metabolite: Possible significance in breast cancer?

    PubMed

    Raeside, James I

    2016-06-01

    Epoxides as reactive intermediates of estrogen metabolism have been considered to be potential precursors of the 2- and 4-hydroxy, catechol estrogens and even to be mutagenic/carcinogenic agents themselves. The labile nature of the intermediates has made proof of their existence difficult in natural biological conditions. In our studies on estrogen metabolism in vitro, in various tissues from several laboratory and domestic species, there was chromatographic evidence of formation of a stable estrogen metabolite that could be seen after incubation with radiolabeled estrone, but not with unlabeled substrate. Investigation with acid treatment of the metabolite yielded material detected as 6-hydroxy-estrone-suggesting the presence of an additional oxygen atom in the molecule. An identification of the "unknown compound" has not yet been made but, with this evidence, the properties revealed so far can best be met by assuming the presence of 5,6-epoxy-estrone. The recent favorable reports on the role of 5α,6α-epoxy-cholesterol in breast cancer has led to the hypothesis that the formation of a similar, stable epoxide of an estrogen could potentially be a compound of interest. If a metabolic pathway from estrone to 6-hydroxy-estrone through a stable epoxide has indeed been observed, it would suggest that identifying and screening for the enzymes responsible for its production, as opposed to those generating the catecholestrogens, could provide valuable information in relation to breast cancer. The balance in production of estrogen epoxides could be a key factor in determining normal health or risk of tumor development. PMID:27142140

  20. A non-canonical caleosin from Arabidopsis efficiently epoxidizes physiological unsaturated fatty acids with complete stereoselectivity.

    PubMed

    Blée, Elizabeth; Flenet, Martine; Boachon, Benoît; Fauconnier, Marie-Laure

    2012-10-01

    In plants, epoxygenated fatty acids (EFAs) are constituents of oil seeds as well as defence molecules and components of biopolymers (cutin, suberin). While the pleiotropic biological activities of mammalian EFAs have been well documented, there is a paucity of information on the physiological relevance of plant EFAs and their biosynthesis. Potential candidates for EFA formation are caleosin-type peroxygenases which catalyze the epoxidation of unsaturated fatty acids in the presence of hydroperoxides as co-oxidants. However, the caleosins characterized so far, which are mostly localized in seeds, are poor epoxidases. In sharp contrast, quantitative RT-PCR analysis revealed that PXG4, a class II caleosin gene, is expressed in roots, stems, leaves and flowers of Arabidopsis. Expressed in yeast, PXG4 encodes a calcium-dependent membrane-associated hemoprotein able to catalyze typical peroxygenase reactions. Moreover, we show here that purified recombinant PXG4 is an efficient fatty acid epoxygenase, catalyzing the oxidation of cis double bonds of unsaturated fatty acids. Physiological linoleic and linolenic acids proved to be the preferred substrates for PXG4; they are oxidized into the different positional isomers of the monoepoxides and into diepoxides. An important regioselectivity was observed; the C-12,13 double bond of these unsaturated fatty acids being the least favored unsaturation epoxidized by PXG4, linolenic acid preferentially yielded the 9,10-15,16-diepoxide. Remarkably, PXG4 catalyzes exclusively the formation of (R),(S)-epoxide enantiomers, which is the absolute stereochemistry of the epoxides found in planta. These findings pave the way for the study of the functional role of EFAs and caleosins in plants. PMID:22913587

  1. The stability of the three transmembrane and the four transmembrane human vitamin K epoxide reductase models

    NASA Astrophysics Data System (ADS)

    Wu, Sangwook

    2016-04-01

    The three transmembrane and the four transmembrane helix models are suggested for human vitamin K epoxide reductase (VKOR). In this study, we investigate the stability of the human three transmembrane/four transmembrane VKOR models by employing a coarse-grained normal mode analysis and molecular dynamics simulation. Based on the analysis of the mobility of each transmembrane domain, we suggest that the three transmembrane human VKOR model is more stable than the four transmembrane human VKOR model.

  2. Imidazolinium salts as catalysts for the ring-opening alkylation of meso epoxides by alkylaluminum complexes.

    PubMed

    Zhou, H; Campbell, E J; Nguyen, S T

    2001-07-12

    [reaction: see text] Imidazolinium salts and their N-heterocyclic carbene (NHC) derivatives catalyze the alkylation of a variety of meso epoxides in the presence of triethylaluminum (yield = 70-90%), under mild conditions. Imidazolinium salts are better catalysts than their NHC derivatives but can lead to dimerization side reactions under extended reaction time. Preformed NHC.AlEt(3) complexes and Wanzlick-type olefins, which are dimers of free NHCs, are also catalysts for this reaction. PMID:11440586

  3. Mechanistic study of secondary organic aerosol components formed from nucleophilic addition reactions of methacrylic acid epoxide

    NASA Astrophysics Data System (ADS)

    Birdsall, A. W.; Miner, C. R.; Mael, L. E.; Elrod, M. J.

    2014-08-01

    Recently, methacrylic acid epoxide (MAE) has been proposed as a precursor to an important class of isoprene-derived compounds found in secondary organic aerosol (SOA): 2-methylglyceric acid (2-MG) and a set of oligomers, nitric acid esters and sulfuric acid esters related to 2-MG. However, the specific chemical mechanisms by which MAE could form these compounds have not been previously studied. In order to determine the relevance of these processes to atmospheric aerosol, MAE and 2-MG have been synthesized and a series of bulk solution-phase experiments aimed at studying the reactivity of MAE using nuclear magnetic resonance (NMR) spectroscopy have been performed. The present results indicate that the acid-catalyzed MAE reaction is more than 600 times slower than a similar reaction of an important isoprene-derived epoxide, but is still expected to be kinetically feasible in the atmosphere on more acidic SOA. The specific mechanism by which MAE leads to oligomers was identified, and the reactions of MAE with a number of atmospherically relevant nucleophiles were also investigated. Because the nucleophilic strengths of water, sulfate, alcohols (including 2-MG), and acids (including MAE and 2-MG) in their reactions with MAE were found to be of a similar magnitude, it is expected that a diverse variety of MAE + nucleophile product species may be formed on ambient SOA. Thus, the results indicate that epoxide chain reaction oligomerization will be limited by the presence of high concentrations of non-epoxide nucleophiles (such as water); this finding is consistent with previous environmental chamber investigations of the relative humidity-dependence of 2-MG-derived oligomerization processes and suggests that extensive oligomerization may not be likely on ambient SOA because of other competitive MAE reaction mechanisms.

  4. Mechanistic study of secondary organic aerosol components formed from nucleophilic addition reactions of methacrylic acid epoxide

    NASA Astrophysics Data System (ADS)

    Birdsall, A. W.; Miner, C. R.; Mael, L. E.; Elrod, M. J.

    2014-12-01

    Recently, methacrylic acid epoxide (MAE) has been proposed as a precursor to an important class of isoprene-derived compounds found in secondary organic aerosol (SOA): 2-methylglyceric acid (2-MG) and a set of oligomers, nitric acid esters, and sulfuric acid esters related to 2-MG. However, the specific chemical mechanisms by which MAE could form these compounds have not been previously studied with experimental methods. In order to determine the relevance of these processes to atmospheric aerosol, MAE and 2-MG have been synthesized and a series of bulk solution-phase experiments aimed at studying the reactivity of MAE using nuclear magnetic resonance (NMR) spectroscopy have been performed. The present results indicate that the acid-catalyzed MAE reaction is more than 600 times slower than a similar reaction of an important isoprene-derived epoxide, but is still expected to be kinetically feasible in the atmosphere on more acidic SOA. The specific mechanism by which MAE leads to oligomers was identified, and the reactions of MAE with a number of atmospherically relevant nucleophiles were also investigated. Because the nucleophilic strengths of water, sulfate, alcohols (including 2-MG), and acids (including MAE and 2-MG) in their reactions with MAE were found to be of similar magnitudes, it is expected that a diverse variety of MAE + nucleophile product species may be formed on ambient SOA. Thus, the results indicate that epoxide chain reaction oligomerization will be limited by the presence of high concentrations of non-epoxide nucleophiles (such as water); this finding is consistent with previous environmental chamber investigations of the relative humidity dependence of 2-MG-derived oligomerization processes and suggests that extensive oligomerization may not be likely on ambient SOA because of other competitive MAE reaction mechanisms.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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...

  11. 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...

  12. 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...

  13. 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.

  14. 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.

  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. Lysophosphatidic acids are new substrates for the phosphatase domain of soluble epoxide hydrolase[S

    PubMed Central

    Oguro, Ami; Imaoka, Susumu

    2012-01-01

    Soluble epoxide hydrolase (sEH) is a bifunctional enzyme that has a C-terminus epoxide hydrolase domain and an N-terminus phosphatase domain. The endogenous substrates of epoxide hydrolase are known to be epoxyeicosatrienoic acids, but the endogenous substrates of the phosphatase activity are not well understood. In this study, to explore the substrates of sEH, we investigated the inhibition of the phosphatase activity of sEH toward 4-methylumbelliferyl phosphate by using lecithin and its hydrolyzed products. Although lecithin itself did not inhibit the phosphatase activity, the hydrolyzed lecithin significantly inhibited it, suggesting that lysophospholipid or fatty acid can inhibit it. Next, we investigated the inhibition of phosphatase activity by lysophosphatidyl choline, palmitoyl lysophosphatidic acid, monopalmitoyl glycerol, and palmitic acid. Palmitoyl lysophosphatidic acid and fatty acid efficiently inhibited phosphatase activity, suggesting that lysophosphatidic acids (LPAs) are substrates for the phosphatase activity of sEH. As expected, palmitoyl, stearoyl, oleoyl, and arachidonoyl LPAs were efficiently dephosphorylated by sEH (Km, 3–7 μM; Vmax, 150–193 nmol/min/mg). These results suggest that LPAs are substrates of sEH, which may regulate physiological functions of cells via their metabolism. PMID:22217705

  17. Persistence and changes in bioavailability of dieldrin, DDE and heptachlor epoxide in earthworms over 45 years

    USGS Publications Warehouse

    Beyer, W. Nelson; Gale, Robert W.

    2013-01-01

    The finding of dieldrin (88 ng/g), DDE (52 ng/g), and heptachlor epoxide (19 ng/g) in earthworms from experimental plots after a single moderate application (9 kg/ha) 45 years earlier attests to the remarkable persistence of these compounds in soil and their continued uptake by soil organisms. Half-lives (with 95 % confidence intervals) in earthworms, estimated from exponential decay equations, were as follows: dieldrin 4.9 (4.3-5.7) years, DDE 5.3 (4.7-6.1) years, and heptachlor epoxide 4.3 (3.8-4.9) years. These half-lives were not significantly different from those estimated after 20 years. Concentration factors (dry weight earthworm tissue/dry weight soil) were initially high and decreased mainly during the first 11 years after application. By the end of the study, average concentration factors were 1.5 (dieldrin), 4.0 (DDE), and 1.8 (heptachlor epoxide), respectively.

  18. Human microsomal epoxide hydrolase: genetic polymorphism and functional expression in vitro of amino acid variants

    PubMed Central

    Hassett, Christopher; Aicher, Lauri; Sidhu, Jaspreet S.

    2016-01-01

    Human microsomal epoxide hydrolase (mEH) is a biotransformation enzyme that metabolizes reactive epoxide intermediates to more water-soluble trans-dihydrodiol derivatives. We compared protein-coding sequences from six full-length human mEH DNA clones and assessed potential amino acid variation at seven positions. The prevalence of these variants was assessed in at least 37 unrelated individuals using polymerase chain reaction experiments. Only Tyr/His 113 (exon 3) and His/Arg 139 (exon 4) variants were observed. The genotype frequencies determined for residue 113 alleles indicate that this locus may not be in Hardy – Weinberg equilibrium, whereas frequencies observed for residue 139 alleles were similar to expected values. Nucleotide sequences coding for the variant amino acids were constructed in an mEH cDNA using site-directed mutagenesis, and each was expressed in vitro by transient transfection of COS-1 cells. Epoxide hydrolase mRNA level, catalytic activity, and immunoreactive protein were evaluated for each construct. The results of these analyses demonstrated relatively uniform levels of mEH RNA expression between the constructs. mEH enzymatic activity and immunoreactive protein were strongly correlated, indicating that mEH specific activity was similar for each variant. However, marked differences were noted in the relative amounts of immunoreactive protein and enzymatic activity resulting from the amino acid substitutions. These data suggest that common human mEH amino acid polymorphisms may alter enzymatic function, possibly by modifying protein stability. PMID:7516776

  19. Reduction of epoxidized vegetable oils: a novel method to prepare bio-based polyols for polyurethanes.

    PubMed

    Zhang, Chaoqun; Ding, Rui; Kessler, Michael R

    2014-06-01

    A novel method, epoxidation/reduction of vegetable oils, is developed to prepare bio-based polyols for the manufacture of polyurethanes (PUs). These polyols are synthesized from castor oil (CO), epoxidized soybean oil, and epoxidized linseed oil and their molecular structures are characterized. They are used to prepare a variety of PUs, and their thermomechanical properties are compared to those of PU made with petroleum-based polyol (P-450). It is shown that PUs made with polyols from soybean and linseed oil exhibit higher glass transition temperatures, tensile strength, and Young's modulus and PU made with polyol from CO exhibits higher elongation at break and toughness than PU made with P-450. However, PU made with P-450 displays better thermal resistance because of tri-ester structure and terminal functional groups. The method provides a versatile way to prepare bio-polyols from vegetable oils, and it is expected to partially or completely replace petroleum-based polyols in PUs manufacture. PMID:24668919

  20. Reaction-based epoxide fluorescent probe for in vivo visualization of hydrogen sulfide.

    PubMed

    Sathyadevi, Palanisamy; Chen, Yu-Jen; Wu, Shou-Cheng; Chen, Yen-Hao; Wang, Yun-Ming

    2015-06-15

    Hydrogen sulfide (H2S) has emerged as the most important biosynthetic gasotransmitters along with nitric oxide (NO) and carbon monoxide (CO). In this study, we report the design and the synthesis of a new epoxide fluorescent probe 7-glycidyloxy-9-(2-glycidyloxycarbonylphenyl)-2-xanthone (FEPO) for use in in vivo visualization of hydrogen sulfide. The probe employs a fluorescein as a fluorophore, and is equipped with an operating epoxide unit. FEPO functions via epoxide ring opening upon nucleophilic attack of H2S. This ring opening strategy may open a new avenue for the development of various H2S fluorescent sensors. FEPO showed high selectivity and high sensitivity for H2S. FEPO's cytotoxicity was tested using MTT (2-(4,5-dimethyl-2-thiazolyl)-3,5-diphenyl-2H-tetrazolium bromide) assay. Furthermore, the use of confocal imaging of H2S and in vivo imaging in live zebra fish demonstrated FEPO's potential biological applications. We anticipate that, owing to their ideal properties, probes of this type will find great uses in exploring the role of H2S in biology. PMID:25660659

  1. Complex Cure Kinetics of the Hydroxyl-Epoxide Reaction in DGEBA Epoxy Hardened with Diethanolamine

    NASA Astrophysics Data System (ADS)

    Ancipink, Windy; McCoy, John; Kropka, Jamie; Celina, Mathias

    The curing of a diglycidyl ether of bisphenol-A Epoxy (Epon 828) with diethanolamine (DEA) involves a fast amine-epoxide reaction followed by a slower hydroxyl-epoxide reaction. At curing temperatures below 100°C, the time scales of these two reactions are well separated, and the hydroxyl addition can be studied as an ''isolated'' reaction. The hydroxyl-epoxide reaction is of great interest due to the complex kinetics involved, which are brought about by competing reactions. The reaction kinetics are believed to be tertiary amine catalyzed and are well fit to a modified form of the Kamal-type equation. Here we study the complex long term reaction kinetics at various temperatures, by using isothermal modulated differential scanning calorimetry, micro calorimetry, and infrared spectroscopy. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  2. Effect of the synthetic method on the catalytic activity of alumina: Epoxidation of cyclohexene

    SciTech Connect

    Valderruten, N.E.; Peña, W.F.; Ramírez, A.E.; Rodríguez-Páez, J.E.

    2015-02-15

    Graphical abstract: Temperature influence on percent conversion and selectivity in the epoxidation of cyclohexene using commercial alumina as a catalyst. - Highlights: • Aluminum oxide was synthesized using Pechini method. • The alumina obtained showed a mix of boehmite and γ-alumina phases. • We research an economically feasible method to obtain alumina for use as a catalyst. • Alumina obtained by Pechini showed high percent conversion and/or selectivity. • The best results were 78% conversion and 78% selectivity to epoxidation reactions. - Abstract: Al{sub 2}O{sub 3} was prepared from different inorganic precursors via the Pechini method and compared with Al{sub 2}O{sub 3} prepared by the sol–gel method. Structural characterization of these materials was carried out by FTIR, X-ray diffraction (XRD), N{sub 2} adsorption at −196 °C and transmission electron microscopy (TEM). The solids were tested in the epoxidation of cyclohexene and a difference in their catalytic activities was observed. The characterization results indicate that the samples prepared by Pechini have a mixture of γ-alumina and boehmite, a condition favoring catalytic activity, whereas the sol–gel sample is less crystalline due to higher boehmite content. These results indicate that both the nature of the precursor and the method of synthesis strongly affect the catalytic activity of Al{sub 2}O{sub 3}.

  3. High biobased content epoxy-anhydride thermosets from epoxidized sucrose esters of Fatty acids.

    PubMed

    Pan, Xiao; Sengupta, Partha; Webster, Dean C

    2011-06-13

    Novel highly functional biobased epoxy compounds, epoxidized sucrose esters of fatty acids (ESEFAs), were cross-linked with a liquid cycloaliphatic anhydride to prepare polyester thermosets. The degree of cure or conversion was studied using differential scanning calorimetry (DSC), and the sol content of the thermosets was determined using solvent extraction. The mechanical properties were studied using tensile testing to determine Young's modulus, tensile stress, and elongation at break. Dynamic mechanical analysis (DMA) was used to determine glass-transition temperature, storage modulus, and cross-link density. The nanomechanical properties of the surfaces were studied using nanoindentation to determine reduced modulus and indentation hardness. The properties of coatings on steel substrates were studied to determine coating hardness, adhesion, solvent resistance, and mechanical durability. Compared with the control, epoxidized soybean oil, the anhydride-cured ESEFAs have high modulus and are hard and ductile, high-performance thermoset materials while maintaining a high biobased content (71-77% in theory). The exceptional performance of the ESEFAs is attributed to the unique structure of these macromolecules: well-defined compact structures with high epoxide functionality. These biobased thermosets have potential uses in applications such as composites, adhesives, and coatings. PMID:21561167

  4. Characterization of an epoxide hydrolase from the Florida red tide dinoflagellate, Karenia brevis.

    PubMed

    Sun, Pengfei; Leeson, Cristian; Zhi, Xiaoduo; Leng, Fenfei; Pierce, Richard H; Henry, Michael S; Rein, Kathleen S

    2016-02-01

    Epoxide hydrolases (EH, EC 3.3.2.3) have been proposed to be key enzymes in the biosynthesis of polyether (PE) ladder compounds such as the brevetoxins which are produced by the dinoflagellate Karenia brevis. These enzymes have the potential to catalyze kinetically disfavored endo-tet cyclization reactions. Data mining of K. brevis transcriptome libraries revealed two classes of epoxide hydrolases: microsomal and leukotriene A4 (LTA4) hydrolases. A microsomal EH was cloned and expressed for characterization. The enzyme is a monomeric protein with molecular weight 44kDa. Kinetic parameters were evaluated using a variety of epoxide substrates to assess substrate selectivity and enantioselectivity, as well as its potential to catalyze the critical endo-tet cyclization of epoxy alcohols. Monitoring of EH activity in high and low toxin producing cultures of K. brevis over a three week period showed consistently higher activity in the high toxin producing culture implicating the involvement of one or more EH in brevetoxin biosynthesis. PMID:26626160

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. Expression and characterization of an epoxide hydrolase from Anopheles gambiae with high activity on epoxy fatty acids

    PubMed Central

    Xu, Jiawen; Morisseau, Christophe; Hammock, Bruce D.

    2014-01-01

    In insects, epoxide hydrolases (EHs) play critical roles in the metabolism of xenobiotic epoxides from the food resources and in the regulation of endogenous chemical mediators, such as juvenile hormones. Using the baculovirus expression system, we expressed and characterized an epoxide hydrolase from Anopheles gambiae (AgEH) that is distinct in evolutionary history from insect juvenile hormone epoxide hydrolases (JHEHs). We partially purified the enzyme by ion exchange chromatography and isoelectric focusing. The experimentally determined molecular weight and pI were estimated to be 35kD and 6.3 respectively, different than the theoretical ones. The AgEH had the greatest activity on long chain epoxy fatty acids such as 14,15-epoxyeicosatrienoic acids (14,15-EET) and 9,10-epoxy-12Z-octadecenoic acids (9,10-EpOME or leukotoxin) among the substrates evaluated. Juvenile hormone III, a terpenoid insect growth regulator, was the next best substrate tested. The AgEH showed kinetics comparable to the mammalian soluble epoxide hydrolases, and the activity could be inhibited by AUDA [12-(3-adamantan-1-yl-ureido) dodecanoic acid], a urea-based inhibitor designed to inhibit the mammalian soluble epoxide hydrolases. The rabbit serum generated against the soluble epoxide hydrolase of Mus musculus can both cross-react with natural and denatured forms of the AgEH, suggesting immunologically they are similar. The study suggests there are mammalian sEH homologs in insects, and epoxy fatty acids may be important chemical mediators in insects. PMID:25173592

  11. 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.

  12. Substrate range and enantioselectivity of epoxidation reactions mediated by the ethene-oxidising Mycobacterium strain NBB4.

    PubMed

    Cheung, Samantha; McCarl, Victoria; Holmes, Andrew J; Coleman, Nicholas V; Rutledge, Peter J

    2013-02-01

    Mycobacterium strain NBB4 is an ethene-oxidising micro-organism isolated from estuarine sediments. In pursuit of new systems for biocatalytic epoxidation, we report the capacity of strain NBB4 to convert a diverse range of alkene substrates to epoxides. A colorimetric assay based on 4-(4-nitrobenzyl)pyridine) has been developed to allow the rapid characterisation and quantification of biocatalytic epoxide synthesis. Using this assay, we have demonstrated that ethene-grown NBB4 cells epoxidise a wide range of alkenes, including terminal (propene, 1-butene, 1-hexene, 1-octene and 1-decene), cyclic (cyclopentene, cyclohexene), aromatic (styrene, indene) and functionalised substrates (allyl alcohol, dihydropyran and isoprene). Apparent specific activities have been determined and range from 2.5 to 12.0 nmol min(-1) per milligram of cell protein. The enantioselectivity of epoxidation by Mycobacterium strain NBB4 has been established using styrene as a test substrate; (R)-styrene oxide is produced in enantiomeric excesses greater than 95%. Thus, the ethene monooxygenase of Mycobacterium NBB4 has a broad substrate range and promising enantioselectivity, confirming its potential as a biocatalyst for alkene epoxidation. PMID:22410742

  13. UV-assisted removal of inactive peroxide species for sustained epoxidation of cyclooctene on anatase TiO2.

    PubMed

    Yang, Changjun; Lang, Xianjun; Ma, Wanhong; Chen, Chuncheng; Ji, Hongwei; Zhao, Jincai

    2014-05-19

    Epoxidation of olefins with H2O2 is one of the most important reactions in organic synthesis. We found that anatase TiO2 can be a good catalyst for the epoxidation of cyclooctene with H2O2 at room temperature. However, the catalyst deactivated quickly in the presence of excess amount of H2O2 because of the formation of inactive side-on Ti-η(2)-peroxide species on the surface of TiO2, the presence of which was confirmed by isotope-labelled resonance UV Raman spectroscopy and kinetics studies. Interestingly, the epoxidation reaction could be dramatically accelerated under irradiation of UV light with λ≥350 nm. This phenomenon is attributed to the photo-assisted removal of the inactive peroxide species, through which the active sites on the surface of anatase TiO2 are regenerated and the catalytic epoxidation of cyclooctene with H2O2 is resumed. This finding provides an alternative for sustained epoxidation reactions on TiO2 at room temperature. Moreover, it also has significant implications on the deactivation pathway and possible solutions in Ti-based heterogeneous catalysis or photocatalysis. PMID:24764202

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  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. 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.

  20. 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

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Strategic use of nickel(0)-catalyzed enyne-epoxide reductive coupling towards the synthesis of (−)-cyatha-3,12-diene

    PubMed Central

    Sparling, Brian A.; Simpson, Graham L.; Jamison, Timothy F.

    2009-01-01

    Various situations are explored in which the nickel(0)-catalyzed enyne-epoxide reductive coupling was utilized to access key intermediates towards the total synthesis of (−)-cyatha-3,12-diene (1). Enantioenriched 3,5-dien-1-ols with a variety of functionality were obtained in a straightforward manner from easily accessible 1,3-enynes and terminal epoxides. PMID:20161213

  7. Soluble epoxide hydrolase expression in a porcine model of arteriovenous graft stenosis and anti-inflammatory effects of a soluble epoxide hydrolase inhibitor

    PubMed Central

    Sanders, William G.; Morisseau, Christophe; Hammock, Bruce D.; Cheung, Alfred K.

    2012-01-01

    Synthetic arteriovenous (AV) grafts, placed between an artery and vein, are used for hemodialysis but often fail due to stenosis, typically at the vein-graft anastomosis. This study recorded T lymphocyte and macrophage accumulation at the vein-graft anastomosis, suggesting a role for inflammation in stenosis development. Epoxyeicosatrienoic acids (EETs), products of cytochrome P-450 epoxidation of arachidonic acid, have vasculoprotective and anti-inflammatory effects including inhibition of platelet activation, cell migration, and adhesion. EETs are hydrolyzed by soluble epoxide hydrolase (sEH) to less active diols. The effects of a specific inhibitor of sEH (sEHI) on cytokine release from human monocytes and mouse bone marrow–derived macrophages (BMMΦ) from wild-type (WT) and sEH knockout (KO) animals were investigated. Expression of sEH protein increased over time at the anastomosis as evaluated by immunohistochemistry. Pre-exposure of adherent human monocytes to sEHI (5 μM) significantly inhibited lipopolysaccharide-induced release of monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor-α and enhanced the EET-to-diol ratio. Release of MCP-1 from WT BMMΦ was significantly inhibited but release from sEH KO BMMΦ was not attenuated indicating the specificity of the sEHI. In contrast, sEHI did not inhibit the release of macrophage inflammatory protein-1 or interleukin-6. Nuclear translocation of NF-κB, as assessed by immunocytochemical staining, was not decreased with sEHI in monocytes, but the phosphorylation of JNK was completely abrogated, suggesting this pathway is the target of sEHI effects in monocytes. These results suggest that sEHI may be useful for inhibition of inflammation and subsequently stenosis in AV grafts. PMID:22621785

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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...

  13. 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.

  14. 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.

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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.

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. Structure of cytochrome P450 PimD suggests epoxidation of the polyene macrolide pimaricin occurs via a hydroperoxoferric intermediate

    PubMed Central

    Kells, Petrea M.; Ouellet, Hugues; Santos-Aberturas, Javier; Aparicio, Jesus F.; Podust, Larissa M.

    2010-01-01

    SUMMARY We present the x-ray structure of PimD, both substrate-free and in complex with 4,5-desepoxypimaricin. PimD is a cytochrome P450 monooxygenase with native epoxidase activity that is critical in the biosynthesis of the polyene macrolide antibiotic pimaricin. Intervention in this secondary metabolic pathway could advance the development of drugs with improved pharmacologic properties. Epoxidation by P450 typically includes formation of a charge-transfer complex between an oxoferryl π-cation radical species (Compound I) and the olefin π-bond as the initial intermediate. Catalytic and structural evidence presented here suggest that epoxidation of 4,5-desepoxypimaricin proceeds via a hydroperoxoferric intermediate (Compound 0). The oxygen atom of Compound 0 distal to the heme iron may insert into the double bond of the substrate to make an epoxide ring. Stereoelectronic features of the putative transition state suggest substrate-assisted proton delivery. PMID:20797613

  7. 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}.

  8. 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.

  9. 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.

  10. The Molecular Structure of Epoxide Hydrolase B From And Its Complex With Urea-Based Inhibitor

    SciTech Connect

    Biswal, B.K.; Morisseau, C.; Garen, G.; Cherney, M.M.; Garen, C.; Niu, C.; Hammock, B.D.; James, M.N.G.

    2009-05-11

    Mycobacterium tuberculosis (Mtb), the intracellular pathogen that infects macrophages primarily, is the causative agent of the infectious disease tuberculosis in humans. The Mtb genome encodes at least six epoxide hydrolases (EHs A to F). EHs convert epoxides to trans-dihydrodiols and have roles in drug metabolism as well as in the processing of signaling molecules. Herein, we report the crystal structures of unbound Mtb EHB and Mtb EHB bound to a potent, low-nanomolar (IC(50) approximately 19 nM) urea-based inhibitor at 2.1 and 2.4 A resolution, respectively. The enzyme is a homodimer; each monomer adopts the classical alpha/beta hydrolase fold that composes the catalytic domain; there is a cap domain that regulates access to the active site. The catalytic triad, comprising Asp104, His333 and Asp302, protrudes from the catalytic domain into the substrate binding cavity between the two domains. The urea portion of the inhibitor is bound in the catalytic cavity, mimicking, in part, the substrate binding; the two urea nitrogen atoms donate hydrogen bonds to the nucleophilic carboxylate of Asp104, and the carbonyl oxygen of the urea moiety receives hydrogen bonds from the phenolic oxygen atoms of Tyr164 and Tyr272. The phenolic oxygen groups of these two residues provide electrophilic assistance during the epoxide hydrolytic cleavage. Upon inhibitor binding, the binding-site residues undergo subtle structural rearrangement. In particular, the side chain of Ile137 exhibits a rotation of around 120 degrees about its C(alpha)-C(beta) bond in order to accommodate the inhibitor. These findings have not only shed light on the enzyme mechanism but also have opened a path for the development of potent inhibitors with good pharmacokinetic profiles against all Mtb EHs of the alpha/beta type.

  11. Assessing the oxidative potential of isoprene-derived epoxides and secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Kramer, Amanda J.; Rattanavaraha, Weruka; Zhang, Zhenfa; Gold, Avram; Surratt, Jason D.; Lin, Ying-Hsuan

    2016-04-01

    Fine particulate matter (PM2.5) is known to contribute to adverse health effects, such as asthma, cardiopulmonary disease, and lung cancer. Secondary organic aerosol (SOA) is a major component of PM2.5 and can be enhanced by atmospheric oxidation of biogenic volatile organic compounds in the presence of anthropogenic pollutants, such as nitrogen oxides (NOx) and sulfur dioxide. However, whether biogenic SOA contributes to adverse health effects remains unclear. The objective of this study was to assess the potential of isoprene-derived epoxides and SOA for generating reactive oxygen species (ROS) in light of the recent recognition that atmospheric oxidation of isoprene in the presence of acidic sulfate aerosol is a major contributor to the global SOA burden. The dithiothreitol (DTT) assay was used to characterize the ROS generation by the isoprene-derived epoxides, trans-β-isoprene epoxydiol (trans-β-IEPOX) and methacrylic acid epoxide (MAE), and their hydrolysis products, the 2-methyltetrol diastereomers (2-MT), 2-methylglyceric acid (2-MG), their organosulfate derivatives, as well as an isoprene-derived hydroxyhydroperoxide (ISOPOOH). In addition, ROS generation potential was evaluated for total SOA produced from photooxidation of isoprene and methacrolein (MACR) as well as from the reactive uptake of trans-β-IEPOX and MAE onto acidified sulfate aerosol. The high-NOx regime, which yields 2-MG-, MAE- and MACR-derived SOA has a higher ROS generation potential than the low-NOx regime, which yields 2-MT, IEPOX- and isoprene-derived SOA. ISOPOOH has an ROS generation potential similar to 1,4-naphthoquinone (1,4-NQ), suggesting a significant contribution of aerosol-phase organic peroxides to PM oxidative potential. MAE- and MACR-derived SOA show equal or greater ROS generation potential than reported in studies on diesel exhaust PM, highlighting the importance of a comprehensive investigation of the toxicity of isoprene-derived SOA.

  12. Determinants of Reactivity and Selectivity in Soluble Epoxide Hydrolase from Quantum Mechanics/Molecular Mechanics Modeling

    PubMed Central

    2012-01-01

    Soluble epoxide hydrolase (sEH) is an enzyme involved in drug metabolism that catalyzes the hydrolysis of epoxides to form their corresponding diols. sEH has a broad substrate range and shows high regio- and enantioselectivity for nucleophilic ring opening by Asp333. Epoxide hydrolases therefore have potential synthetic applications. We have used combined quantum mechanics/molecular mechanics (QM/MM) umbrella sampling molecular dynamics (MD) simulations (at the AM1/CHARMM22 level) and high-level ab initio (SCS-MP2) QM/MM calculations to analyze the reactions, and determinants of selectivity, for two substrates: trans-stilbene oxide (t-SO) and trans-diphenylpropene oxide (t-DPPO). The calculated free energy barriers from the QM/MM (AM1/CHARMM22) umbrella sampling MD simulations show a lower barrier for phenyl attack in t-DPPO, compared with that for benzylic attack, in agreement with experiment. Activation barriers in agreement with experimental rate constants are obtained only with the highest level of QM theory (SCS-MP2) used. Our results show that the selectivity of the ring-opening reaction is influenced by several factors, including proximity to the nucleophile, electronic stabilization of the transition state, and hydrogen bonding to two active site tyrosine residues. The protonation state of His523 during nucleophilic attack has also been investigated, and our results show that the protonated form is most consistent with experimental findings. The work presented here illustrates how determinants of selectivity can be identified from QM/MM simulations. These insights may also provide useful information for the design of novel catalysts for use in the synthesis of enantiopure compounds. PMID:22280021

  13. The Nature of the Reaction Intermediates in the FAD-Dependent Epoxidation Mechanism of Styrene Monooxygenase*

    PubMed Central

    Kantz, Auric; Gassner, George T.

    2010-01-01

    Styrene monooxygenase (SMO) is a two-component flavoenzyme composed of an NADH-specific flavin reductase (SMOB) and FAD-specific styrene epoxidase (NSMOA). NSMOA binds tightly to reduced FAD and catalyzes the stereospecific addition of one atom of molecular oxygen to the vinyl side chain of styrene in the enantioselective synthesis of S-styrene oxide. In this mechanism, molecular oxygen first reacts with NSMOA(FADred) to yield an FAD C(4a)- peroxide intermediate. This species is non-fluorescent and has an absorbance maximum of 382 nm. Styrene then reacts with the peroxide intermediate with a second order rate constant of 2.6 × 106 ± 0.1 × 106 M−1 s−1 to yield a fluorescent intermediate with an absorbance maximum of 368 nm. We compute an activation free energy of 8.7 kcal.mol∙−1 for the oxygenation step in good agreement with that expected for a peroxide-catalyzed epoxidation, and acid-quenched samples recovered at defined time points in the single-turnover reaction indicate that styrene oxide synthesis is coincident with the formation phase of the fluorescent intermediate. These findings support FAD C(4a)-peroxide as the oxygen atom donor and identity of the fluorescent intermediate as an FAD C(4a)-hydroxide product of the styrene epoxidation. Overall, four pH-dependent rate constants corresponding to peroxyflavin formation (pKa = 7.2), styrene epoxidation (pKa = 7.7), styrene oxide dissociation (pKa = 8.3), and hydroxyflavin dehydration (pKa 7.6) are needed to fit the single-turnover kinetics. PMID:21166448

  14. Stereospecific biocatalytic epoxidation: the first example of direct regeneration of a FAD-dependent monooxygenase for catalysis.

    PubMed

    Hollmann, Frank; Lin, Po-Chi; Witholt, Bernard; Schmid, Andreas

    2003-07-01

    Catalysis for chemical synthesis by cell-free monooxygenases necessitates an efficient and robust in situ regeneration system to supply the enzyme with reducing equivalents. We report on a novel approach to directly regenerate flavin-dependent monooxygenases. The organometallic complex [CpRh(bpy)(H(2)O)](2+) catalyzes the transhydrogenation reaction between formate and isoalloxazine-based cofactors such as FAD and FMN. Coupling this FADH(2) regeneration reaction to the FADH(2)-dependent styrene monooxygenase (StyA) resulted in a chemoenzymatic epoxidation reaction where the organometallic compound substitutes for the native reductase (StyB), the nicotinamide coenzyme (NAD), and an artificial NADH regeneration system such as formate dehydrogenase. Various styrene derivatives were converted into the essentially optically pure (S)-epoxides (ee > 98%). In addition, StyA was shown to be capable of performing sulfoxidation reactions. The productivity of the chemoenzymatic epoxidation reaction using 6.5 microM StyA reached up to 6.4 mM/h, corresponding to approximately 70% of a comparable fully enzymatic reaction using StyB, NADH, and formate dehydrogenase for regeneration. The coupling efficiency of the nonenzymatic regeneration reaction to enzymatic epoxidation was examined in detail, leading to an optimized reaction setup with minimized quenching of the electron supply for the epoxidation reaction. Thus, up to 60% of the reducing equivalents provided via [CpRh(bpy)(H(2)O)](2+) could be channeled into epoxide rather than hydrogen peroxide formation, allowing selective synthesis with high yields. PMID:12837091

  15. 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.

  16. 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.

  17. How the Proximal Pocket May Influence the Enantiospecificities of Chloroperoxidase-Catalyzed Epoxidations of Olefins

    PubMed Central

    Morozov, Alexander N.; Chatfield, David C.

    2016-01-01

    Chloroperoxidase-catalyzed enantiospecific epoxidations of olefins are of significant biotechnological interest. Typical enantiomeric excesses are in the range of 66%–97% and translate into free energy differences on the order of 1 kcal/mol. These differences are generally attributed to the effect of the distal pocket. In this paper, we show that the influence of the proximal pocket on the electron transfer mechanism in the rate-limiting event may be just as significant for a quantitatively accurate account of the experimentally-measured enantiospecificities. PMID:27517911

  18. Technological Aspects of Chemoenzymatic Epoxidation of Fatty Acids, Fatty Acid Esters and Vegetable Oils: A Review.

    PubMed

    Milchert, Eugeniusz; Malarczyk, Kornelia; Kłos, Marlena

    2015-01-01

    The general subject of the review is analysis of the effect of technological parameters on the chemoenzymatic epoxidation processes of vegetable oils, fatty acids and alkyl esters of fatty acids. The technological parameters considered include temperature, concentration, amount of hydrogen peroxide relative to the number of unsaturated bonds, the amounts of enzyme catalysts, presence of solvent and amount of free fatty acids. Also chemical reactions accompanying the technological processes are discussed together with different technological options and significance of the products obtained. PMID:26633342

  19. Manganese(II)/Picolinic Acid Catalyst System for Epoxidation of Olefins.

    PubMed

    Moretti, Ross A; Du Bois, J; Stack, T Daniel P

    2016-06-01

    An in situ generated catalyst system based on Mn(CF3SO3)2, picolinic acid, and peracetic acid converts an extensive scope of olefins to their epoxides at 0 °C in <5 min, with remarkable oxidant efficiency and no evidence of radical behavior. Competition experiments indicate an electrophilic active oxidant, proposed to be a high-valent Mn = O species. Ligand exploration suggests a general ligand sphere motif contributes to effective oxidation. The method is underscored by its simplicity and use of inexpensive reagents to quickly access high value-added products. PMID:27191036

  20. Rhodium-Catalyzed Endo-Selective Epoxide-Opening Cascades: Formal Synthesis of (−)-Brevisin

    PubMed Central

    Armbrust, Kurt W.; Beaver, Matthew G.; Jamison, Timothy F.

    2015-01-01

    [Rh(CO)2Cl]2 is as an effective catalyst for endo-selective cyclizations and cascades of epoxy-(E)-enoate alcohols, thus enabling the synthesis of oxepanes and oxepane-containing polyethers from di- and trisubstituted epoxides. Syntheses of the ABC and EF ring systems of (−)-brevisin via all endo-diepoxide-opening cascades using this method constitute a formal total synthesis and demonstrate the utility of this methodology in the context of the synthesis of marine ladder polyether natural products. PMID:25984951

  1. Enantioselective cross-coupling of meso-epoxides with aryl halides.

    PubMed

    Zhao, Yang; Weix, Daniel J

    2015-03-11

    The first enantioselective cross-electrophile coupling of aryl bromides with meso-epoxides to form trans-β-arylcycloalkanols is presented. The reaction is catalyzed by a combination of (bpy)NiCl2 and a chiral titanocene under reducing conditions. Yields range from 57 to 99% with 78-95% enantiomeric excess. The 30 examples include a variety of functional groups (ether, ester, ketone, nitrile, ketal, trifluoromethyl, sulfonamide, sulfonate ester), both aryl and vinyl halides, and five- to seven-membered rings. The intermediacy of a carbon radical is strongly suggested by the conversion of cyclooctene monoxide to an aryl [3.3.0]bicyclooctanol. PMID:25716775

  2. Microbiological Transformations. 33. Fungal Epoxide Hydrolases Applied to the Synthesis of Enantiopure Para-Substituted Styrene Oxides. A Mechanistic Approach.

    PubMed

    Pedragosa-Moreau, S.; Morisseau, C.; Zylber, J.; Archelas, A.; Baratti, J.; Furstoss, R.

    1996-10-18

    The biohydrolysis of differently para-substituted styrene oxide derivatives was studied, using whole cells of the fungi Aspergillus niger or Beauveria sulfurescens. These microorganisms proved to be equipped with epoxide hydrolases which are able to achieve these hydrolyses with high enantioselectivity. This allowed the preparation of the optically active epoxides and of the corresponding vicinal diols which were obtained with good to excellent enantiomeric purity. These two microorganisms proved to be enantiocomplementary. A mechanistic study, carried out using a crude lyophilized enzymatic extract from A.niger, indicated via Hammet coefficient plotting that this hydrolysis is very probably due to a general base-catalyzed process. PMID:11667667

  3. Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

    PubMed Central

    Rulev, Yuri A; Gugkaeva, Zalina; Maleev, Victor I

    2015-01-01

    Summary Two new one-component aluminium-based catalysts for the reaction between epoxides and carbon dioxide have been prepared. The catalysts are composed of aluminium–salen chloride complexes with trialkylammonium groups directly attached to the aromatic rings of the salen ligand. With terminal epoxides, the catalysts induced the formation of cyclic carbonates under mild reaction conditions (25–35 °C; 1–10 bar carbon dioxide pressure). However, with cyclohexene oxide under the same reaction conditions, the same catalysts induced the formation of polycarbonate. The catalysts could be recovered from the reaction mixture and reused. PMID:26664580

  4. Synthesis and structure-activity relationship of piperidine-derived non-urea soluble epoxide hydrolase inhibitors

    SciTech Connect

    Pecic, Stevan; Pakhomova, Svetlana; Newcomer, Marcia E.; Morisseau, Christophe; Hammock, Bruce D.; Zhu, Zhengxiang; Rinderspacher, Alison; Deng, Shi-Xian

    2013-09-27

    A series of potent amide non-urea inhibitors of soluble epoxide hydrolase (sEH) is disclosed. The inhibition of soluble epoxide hydrolase leads to elevated levels of epoxyeicosatrienoic acids (EETs), and thus inhibitors of sEH represent one of a novel approach to the development of vasodilatory and anti-inflammatory drugs. Structure–activities studies guided optimization of a lead compound, identified through high-throughput screening, gave rise to sub-nanomolar inhibitors of human sEH with stability in human liver microsomal assay suitable for preclinical development.

  5. Metal complex-catalyzed epoxidation of olefins by dioxygen with co-oxidation of aldehydes: A mechanistic study

    SciTech Connect

    Nam, W.; Kim, H.J.; Kim, S.H.

    1996-02-14

    Mechanistic studies of the oxidation of olefins by dioxygen plus aldehyde in the presence of metal complexes such as metalloporphyrins and metal cyclam complexes have been carried out. Epoxides were the predominant products, with trace amounts of allylic oxidation products. cis-Stilbene was oxidized to a mixture of cis- and trans-stilbene oxides. It is concluded from this study that the principal role of the metal complexes is to aid in the initiation step for the free radical autoxidation of the aldehyde and that acylperoxy radicals generated in the autoxidation reaction (or metal complexes formed by complexation of the acylperoxy radicals) are the active epoxidizing agents.

  6. Effect of warfarin on plasma and liver vitamin K levels and vitamin K epoxide reductase activity in relation to plasma clotting factor levels in rats.

    PubMed

    Yamanaka, Y; Yamano, M; Yasunaga, K; Shike, T; Uchida, K

    1990-01-15

    Changes in plasma and liver vitamin K1 and vitamin K1 epoxide levels, liver microsomal vitamin K epoxide reductase activity, and plasma clotting factor II and VII levels were determined in rats after a single injection of warfarin (2.5 mg/kg, s.c.). The plasma and liver vitamin K1 levels gradually decreased after warfarin injection, attaining the lowest values at 2-3 hrs and remaining low for 48 hrs. They then returned to the control levels at 72 hrs. The changes in vitamin K1 epoxide levels were opposite, with an increase being seen soon after the warfarin injection, the highest values at 3 hrs and a gradual decrease to the initial levels occurring subsequently. The combined levels of vitamin K1 plus vitamin K1 epoxide, however, remained almost constant in both plasma and liver after the warfarin injection. The liver vitamin K epoxide reductase activity decreased to its lowest level soon after the injection and then gradually increased after 12 hrs, but the activity at 72 hrs was only about 30% of the initial activity. The plasma clotting factor levels gradually decreased after the injection, bottomed at 24 hrs and then began to increase, recovering almost to the initial levels at 72 hrs. A positive correlation was found between plasma and liver levels for both vitamin K1 and vitamin K1 epoxide, and the slope of the vitamin K1 epoxide curve was steeper than that for vitamin K1 in the warfarin-treated rats. A similar positive correlation was found for both vitamin K1 and vitamin K1 epoxide after vitamin K1 injection in normal untreated rats, but the slope of the vitamin K1 epoxide curve was much shallower. These results suggest that warfarin inhibits vitamin K epoxide reductase and decreases blood clotting factor synthesis, thus increasing plasma and liver vitamin K1 epoxide levels. A vitamin K epoxide reductase activity one third of that in normal rats is sufficient to maintain normal reduction of vitamin K1 epoxide and synthesis of blood clotting factors. PMID

  7. 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.

  8. Phosphotungstic acid supported on magnetic nanoparticles as an efficient reusable catalyst for epoxidation of alkenes

    SciTech Connect

    Kooti, M.; Afshari, M.

    2012-11-15

    Highlights: ► Phosphotungstic acid supported on functionalized cobalt ferrite was prepared. ► Silica coated cobalt ferrite nanoparticles were used as support. ► This composite was successfully used as catalyst for epoxidation of alkenes. ► Oxidation reactions were carried out in the presence of t-BuOOH as oxidant. ► The catalyst can be readily separated from solution by magnetic field. -- Abstract: A new magnetically separable catalyst consisting of phosphotungstic acid supported on imidazole functionalized silica coated cobalt ferrite nanoparticles was prepared. The synthesized catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). This immobilized phosphotungstic acid was shown to be an efficient heterogeneous catalyst for the epoxidation of various alkenes using tert-butylhydroperoxide (t-BuOOH) as oxidant. The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no significant loss of catalytic activity.

  9. MWCNTs-reinforced epoxidized linseed oil plasticized polylactic acid nanocomposite and its electroactive shape memory behaviour.

    PubMed

    Alam, Javed; Alam, Manawwer; Raja, Mohan; Abduljaleel, Zainularifeen; Dass, Lawrence Arockiasamy

    2014-01-01

    A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs) was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA) was first plasticized by epoxidized linseed oil (ELO) in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %), with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC), tensile test, and thermo gravimetric analysis (TGA). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME) in the resulting nanocomposite was investigated by a fold-deploy "U"-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices. PMID:25365179

  10. Seasonal changes of violaxanthin cycle pigment de-epoxidation in wintergreen and evergreen plants.

    PubMed

    Dymova, Olga; Golovko, Tamara

    2012-01-01

    We studied carotenoids composition and the activities of the xanthophylls pigments in evergreen conifers (Abies sibirica, Juniperus communis, Picea obovata) and dwarf-shrub (Vaccinium vitis-idaea), and in wintergreen herbaceous plants (Ajuga reptans, Pyrola rotundifolia) growing near Syktyvkar (61°67(/) N 50°77(/) E). The carotenoid pool consisted mainly of following xanthophylls: lutein (70%), neoxanthin (7-10%) and a xanthophylls cycle component - violaxanthin (3-15%). Zeaxanthin and antheraxanthin were found in conifer samples collected in December-March while in other species - during all year. A direct connection between xanthophyll pigment de-epoxidation level and light energy thermal dissipation was shown only for boreal conifer species. It is proposed that zeaxanthin plays a central role in the dissipation of excess excitation energy (nonphotochemical quenching) in the antenna of photosystem II (PSII). We conclude that the increase in the extent of de-epoxidation is beneficial for the retention of PSII activity for conifers in early spring and for herbs in summer. PMID:22428127

  11. Epoxidized soybean oil/ZnO biocomposites for soft tissue applications: preparation and characterization.

    PubMed

    Díez-Pascual, Ana M; Díez-Vicente, Angel L

    2014-10-01

    Biocompatible and biodegradable nanocomposites comprising epoxidized soybean oil (ESO) as matrix, zinc oxide (ZnO) nanoparticles as reinforcements, and 4-dimethylaminopyridine (DMAP) as a catalyst have been successfully prepared via epoxidization of the double bonds of the vegetable oil, ultrasonication, and curing without the need for interfacial modifiers. Their morphology, water uptake, thermal, mechanical, barrier, tribological, and antibacterial properties have been investigated. FT-IR analysis revealed the existence of strong ESO-ZnO hydrogen-bonding interactions. The nanoparticles acted as mass transport barriers, hindering the diffusion of volatiles generated during the decomposition process and leading to higher thermal stability, and also reduced the water absorption and gas permeability of the bioresin. Significant improvements in the static and dynamic mechanical properties, such as storage and Young's moduli, tensile strength, toughness, hardness, glass transition, and heat distortion temperature, were attained on reinforcement. A small drop in the nanocomposite stiffness and strength was found after exposure to several cycles of steam sterilization or to simulated body fluid (SBF) at physiological temperature. Extraordinary reductions in the coefficient of friction and wear rate were detected under both dry and SBF conditions, confirming the potential of these nanoparticles for improving the tribological performance of ESO. The nanocomposites displayed antimicrobial action against human pathogen bacteria with and without UV illumination, which increased progressively with the ZnO content. These sustainable, ecofriendly, and low-cost biomaterials are very promising for use in biomedical applications, like structural tissue engineering scaffolds. PMID:25222018

  12. Molecular and biochemical characterization of juvenile hormone epoxide hydrolase from the silkworm, Bombyx mori.

    PubMed

    Zhang, Qi-Rui; Xu, Wei-Hua; Chen, Fu-Sheng; Li, Sheng

    2005-02-01

    One major route of insect juvenile hormone (JH) degradation is epoxide hydration by JH epoxide hydrolase (JHEH). A full-length cDNA (1536 bp) encoding a microsomal JHEH was isolated from the silkworm, Bombyx mori. Bommo-JHEH cDNA contains an open reading frame encoding a 461-amino acid protein (52 kDa), which reveals a high degree of similarity to the previously reported insect JHEHs. The residues Tyr298, Tyr373, and the HGWP motif corresponding to the oxyanion hole of JHEHs and the residues Asp227, His430, and Glu403 in the catalytic triad are well conserved in Bommo-JHEH. Bommo-JHEH was highly expressed in the fat body, where its mRNA expression pattern was in contrast to the pattern of hemolymph levels of JH during the larval development, suggesting that Bommo-JHEH plays an important role in JH degradation. Recombinant Bommo-JHEH (52 kDa) expressed in Sf9 insect cells was membrane-bound and had a high level of enzyme activity (300-fold over the control activity). This Bommo-JHEH study provides a better understanding of how JH levels are regulated in the domesticated silkworm. PMID:15681225

  13. Heavy chain single-domain antibodies to detect native human soluble epoxide hydrolase.

    PubMed

    Cui, Yongliang; Li, Dongyang; Morisseau, Christophe; Dong, Jie-Xian; Yang, Jun; Wan, Debin; Rossotti, Martín A; Gee, Shirley J; González-Sapienza, Gualberto G; Hammock, Bruce D

    2015-09-01

    The soluble epoxide hydrolase (sEH) is a potential pharmacological target for treating hypertension, vascular inflammation, pain, cancer, and other diseases. However, there is not a simple, inexpensive, and reliable method to estimate levels of active sEH in tissues. Toward developing such an assay, a polyclonal variable domain of heavy chain antibody (VHH) sandwich immunoassay was developed. Ten VHHs, which are highly selective for native human sEH, were isolated from a phage-displayed library. The ten VHHs have no significant cross-reactivity with human microsomal epoxide hydrolase, rat and mouse sEH, and denatured human sEH. There is a high correlation between protein levels of the sEH determined by the enzyme-linked immunosorbent assay (ELISA) and the catalytic activity of the enzyme in S9 fractions of human tissues (liver, kidney, and lung). The VHH-based ELISA appears to be a new reliable method for monitoring the sEH and may be useful as a diagnostic tool for diseases influenced by sEH. This study also demonstrates the broad utility of VHH in biochemical and pharmacological research. PMID:26229025

  14. Soluble epoxide hydrolase as an anti-inflammatory target of the thrombolytic stroke drug SMTP-7.

    PubMed

    Matsumoto, Naoki; Suzuki, Eriko; Ishikawa, Makoto; Shirafuji, Takumi; Hasumi, Keiji

    2014-12-26

    Although ischemic stroke is a major cause of death and disability worldwide, only a small fraction of patients benefit from the current thrombolytic therapy due to a risk of cerebral hemorrhage caused by inflammation. Thus, the development of a new strategy to combat inflammation during thrombolysis is an urgent demand. The small molecule thrombolytic SMTP-7 effectively treats ischemic stroke in several animal models with reducing cerebral hemorrhage. Here we revealed that SMTP-7 targeted soluble epoxide hydrolase (sEH) to suppress inflammation. SMTP-7 inhibited both of the two sEH enzyme activities: epoxide hydrolase (which inactivates anti-inflammatory epoxy-fatty acids) and lipid phosphate phosphatase. SMTP-7 suppressed epoxy-fatty acid hydrolysis in HepG2 cells in culture, implicating the sEH inhibition in the anti-inflammatory mechanism. The sEH inhibition by SMTP-7 was independent of its thrombolytic activity. The simultaneous targeting of thrombolysis and sEH by a single molecule is a promising strategy to revolutionize the current stroke therapy. PMID:25361765

  15. Epoxidation of olefins catalysed by vanadium-salan complexes: a theoretical mechanistic study.

    PubMed

    Kuznetsov, Maxim L; Pessoa, João Costa

    2009-07-28

    Plausible mechanisms of olefin epoxidation catalysed by a V-salan model complex [VIV(=O)(L)(H2O)] (1, L=(CH2NHCH2CH=CHO-)2) in the presence of H2O2 are investigated and compared by theoretical methods using density functional theory. Three main routes, i.e. the Mimoun, Sharpless and biradical mechanisms, were examined in detail, and the Sharpless pathway was found to be the most favourable one. The reaction starts from the formation of an active catalytic species [VV(=O)(OO)(LH)] (3c) upon interaction of 1 with H2O2, then concerted, highly synchronous attack of the olefin to 3c occurs yielding the epoxide and catalyst [VV(=O)2(LH)], the latter being oxidized by H2O2 to 3c. The activation barrier strongly depends on the proton location in the catalyst molecule and is the lowest when one of the oxygen atoms of the salan ligand is protonated and the vanadium atom is penta-coordinated with one vacant coordination position (complex 3c). The olefin in this reaction acts as an electron donor (nucleophile) rather than as an electron acceptor (electrophile). PMID:19587988

  16. Soluble Epoxide Hydrolase as an Anti-inflammatory Target of the Thrombolytic Stroke Drug SMTP-7*

    PubMed Central

    Matsumoto, Naoki; Suzuki, Eriko; Ishikawa, Makoto; Shirafuji, Takumi; Hasumi, Keiji

    2014-01-01

    Although ischemic stroke is a major cause of death and disability worldwide, only a small fraction of patients benefit from the current thrombolytic therapy due to a risk of cerebral hemorrhage caused by inflammation. Thus, the development of a new strategy to combat inflammation during thrombolysis is an urgent demand. The small molecule thrombolytic SMTP-7 effectively treats ischemic stroke in several animal models with reducing cerebral hemorrhage. Here we revealed that SMTP-7 targeted soluble epoxide hydrolase (sEH) to suppress inflammation. SMTP-7 inhibited both of the two sEH enzyme activities: epoxide hydrolase (which inactivates anti-inflammatory epoxy-fatty acids) and lipid phosphate phosphatase. SMTP-7 suppressed epoxy-fatty acid hydrolysis in HepG2 cells in culture, implicating the sEH inhibition in the anti-inflammatory mechanism. The sEH inhibition by SMTP-7 was independent of its thrombolytic activity. The simultaneous targeting of thrombolysis and sEH by a single molecule is a promising strategy to revolutionize the current stroke therapy. PMID:25361765

  17. LDRD final report on new homogeneous catalysts for direct olefin epoxidation (LDRD 52591).

    SciTech Connect

    Goldberg, Karen; Smythe, Nicole A.; Moore, Joshua T.; Stewart, Constantine A.; Kemp, Richard Alan; Miller, James Edward; Kornienko, Alexander (New Mexico Institute of Mining and Technology); Denney, Melanie C. (University of Washington); Cetto, Kara L.

    2006-02-01

    This report summarizes our findings during the study of a novel homogeneous epoxidation catalyst system that uses molecular oxygen as the oxidant, a ''Holy Grail'' in catalysis. While olefins (alkenes) that do not contain allylic hydrogens can be epoxidized directly using heterogeneous catalysts, most olefins cannot, and so a general, atom-efficient route is desired. While most of the work performed on this LDRD has been on pincer complexes of late transition metals, we also scouted out metal/ligand combinations that were significantly different, and unfortunately, less successful. Most of the work reported here deals with phosphorus-ligated Pd hydrides [(PCP)Pd-H]. We have demonstrated that molecular oxygen gas can insert into the Pd-H bond, giving a structurally characterized Pd-OOH species. This species reacts with oxygen acceptors such as olefins to donate an oxygen atom, although in various levels of selectivity, and to generate a [(PCP)Pd-OH] molecule. We discovered that the active [(PCP)Pd-H] active catalyst can be regenerated by addition of either CO or hydrogen. The demonstration of each step of the catalytic cycle is quite significant. Extensions to the pincer-Pd chemistry by attaching a fluorinated tail to the pincer designed to be used in solvents with higher oxygen solubilities are also presented.

  18. Epoxidized Soybean Oil: Evaluation of Oxidative Stabilization and Metal Quenching/Heat Transfer Performance

    NASA Astrophysics Data System (ADS)

    Simencio Otero, Rosa L.; Canale, Lauralice C. F.; Said Schicchi, Diego; Agaliotis, Eliana; Totten, George E.; Sánchez Sarmiento, Gustavo

    2013-07-01

    Vegetable and animal oils as a class of fluids have been used for hundreds of years, if not longer, as quenchants for hardening steel. However, when petroleum oils became available in the late 1800s and early 1900s, the use of these fluids as quenchants, in addition to their use in other industrial oil applications, quickly diminished. This was primarily, but not exclusively, due to their generally very poor thermal-oxidative instability and the difficulty for formulating fluid analogs with varying viscosity properties. Interest in the use of renewable fluids, such as vegetable oils, has increased dramatically in recent years as alternatives to the use of relatively non-biodegradable and toxic petroleum oils. However, the relatively poor thermal-oxidative stability has continued to be a significant reason for their general non-acceptance in the marketplace. Soybean oil (SO) is one of the most highly produced vegetable oils in Brazil. Currently, there are commercially produced epoxidized versions of SO which are available. The objective of this paper is to discuss the potential use of epoxidized SO and its heat transfer properties as a viable alternative to petroleum oils for hardening steel.

  19. Rapid purification of cytosolic epoxide hydrolase from normal and clofibrate-treated animals by affinity chromatography.

    PubMed Central

    Prestwich, G D; Hammock, B D

    1985-01-01

    Epoxide hydrolase from liver cytosol (cEH) of both normal and clofibrate-treated mice can be bioselectively adsorbed onto an affinity column prepared from epoxy-activated Sepharose and 7-methoxycitronellyl thiol. The free ligand is a modest inhibitor of cEH (I50, approximately equal to 3 X 10(-4) M) and lacks the epoxide function necessary for it to be turned over as a substrate. This study demonstrates that a methoxy group can be used to mimic an oxirane in a vertebrate system. Bioselective elution of cEH can be accomplished with several chalcone oxides, which are selective potent inhibitors (I50, 1-50 X 10(-7) M), and activity can be recovered by dialysis. This procedure thus enhances the purification by offering independent opportunities for selective binding and selective elution. Conservatively, a 40%-80% recovery of partially inhibited enzyme activity can be achieved in 4-48 hr with a 30- to 90-fold purification. The purified cEH from clofibrate-induced animals was essentially homogeneous by NaDodSO4/PAGE and had an apparent subunit molecular weight of 58,000. The cEHs from normal and clofibrate-induced animals appeared identical by NaDodSO4/PAGE. Since the cEH activity in normal and clofibrate-treated animals is due to the same enzyme, the increase in cEH activity caused by selected hypolipidemic agents appears to be true induction. Images PMID:3856846

  20. The Cloning and Characterization of a Soluble Epoxide Hydrolase in Chicken

    PubMed Central

    Harris, T. R.; Morisseau, C.; Walzem, R. L.; Ma, S. J.; Hammock, B. D.

    2006-01-01

    The mammalian soluble epoxide hydrolase (sEH) plays a role in the regulation of blood pressure and vascular homeostasis through its hydrolysis of the endothelial-derived messenger molecules, the epoxyeicosatrienoic acids. This study reports the cloning and expression of a sEH homolog from chicken liver. The resulting 63-kDa protein has an isoelectric point of 6.1. The recombinant enzyme displayed epoxide hydrolase activity when assayed with [3H]-trans-1,3-diphenylpropene oxide (t-DPPO), as well as trans-9,10-epoxystearate and the cis-8,9-, 11,12-, and 14,15- epoxyeicosatrienoic acids. The chicken enzyme displayed a lower kcat:Km for t-DPPO than the mammalian enzymes. The enzyme was sensitive to urea-based inhibitors developed for mammalian sEH. Such compounds could be used to study the role of chicken sEH in conditions in which endothelial-derived vasodilation is believed to be impaired, such as pulmonary hypertension syndrome. PMID:16523628

  1. Epoxidation of soybean oil catalyzed by peroxo phosphotungstic acid supported on modified halloysite nanotubes

    NASA Astrophysics Data System (ADS)

    Jiang, Junqing; Zhang, Yanwu; Yan, Liwei; Jiang, Pingkai

    2012-06-01

    {PO4[W(O)(O2)2]4}3- was supported onto modified halloysite nanotubes (HNTs) to prepare heterogeneous catalysts and these catalysts were applied in epoxidation of soybean oil. To enhance the cohesive force between {PO4[W(O)(O2)2]4}3- and HNTs, quaternary amino groups were anchored onto HNTs through silylation of N-(2-aminoethyl)-3-aminopropyl trimethoxysilane and alkylation of amino groups. Further {PO4[W(O)(O2)2]4}3- was supported onto HNTs by ion exchange. The heterogeneous catalysts were characterized by FTIR, TGA, XRF and TEM-EDS. Then the catalytic behaviour to epoxidation of soybean oil was studied in detail. The results show that the introduction of phase transfer agent during preparation of the catalysts is very effective to improve catalytic activity and mechanical agitation combining with ultrasonic agitation is the best agitation way. The catalytic reactivity increased as reaction time increased. Moreover, the catalysts can be easily recovered from the reaction system by centrifugation as deposit and recycled three times without obviously decreasing the catalytic activity. Through re-exchange of {PO4[W(O)(O2)2]4}3-, the heterogeneous catalyst can be regenerated without catalytic activity loss.

  2. Soluble Epoxide Hydrolase Homologs in Strongylocentrotus purpuratus Suggest a Gene Duplication Event and Subsequent Divergence

    PubMed Central

    Harris, Todd R.; Aronov, Pavel A.

    2008-01-01

    The mammalian soluble epoxide hydrolase (sEH) is a multidomain enzyme composed of C- and N-terminal regions that contain active sites for epoxide hydrolase (EH) and phosphatase activities, respectively. We report the cloning of two 60 kDa multidomain enzymes from the purple sea urchin Strongylocentrotus purpuratus displaying significant sequence similarity to both the N- and C-terminal domains of the mammalian sEH. While one urchin enzyme did not exhibit EH activity, the second enzyme hydrolyzed several lipid messenger molecules metabolized by the mammalian sEH, including the epoxyeicosatrienoic acids. Neither of the urchin enzymes displayed phosphatase activity. The urchin EH was inhibited by small molecule inhibitors of the mammalian sEH and is the likely ancestor of the enzyme. Sequence comparisons suggest that the urchin sEH homologs are the result of a gene fusion event between a gene encoding for an EH and a gene for an enzyme of undetermined function. This fusion event was followed by a duplication event to produce the urchin enzymes. PMID:18554159

  3. A novel activity of microsomal epoxide hydrolase: metabolism of the endocannabinoid 2-arachidonoylglycerol

    PubMed Central

    Nithipatikom, Kasem; Endsley, Michael P.; Pfeiffer, Adam W.; Falck, John R.; Campbell, William B.

    2014-01-01

    Microsomal epoxide hydrolase (EPHX1, EC 3.3.2.9) is a highly abundant α/β-hydrolase enzyme that is known for its catalytical epoxide hydrolase activity. A wide range of EPHX1 functions have been demonstrated including xenobiotic metabolism; however, characterization of its endogenous substrates is limited. In this study, we present evidence that EPHX1 metabolizes the abundant endocannabinoid 2-arachidonoylglycerol (2-AG) to free arachidonic acid (AA) and glycerol. The EPHX1 metabolism of 2-AG was demonstrated using commercially available EPHX1 microsomes as well as PC-3 cells overexpressing EPHX1. Conversely, EPHX1 siRNA markedly reduced the EPHX1 expression and 2-AG metabolism in HepG2 cells and LNCaP cells. A selective EPHX1 inhibitor, 10-hydroxystearamide, inhibited 2-AG metabolism and hydrolysis of a well-known EPHX1 substrate, cis-stilbene oxide. Among the inhibitors studied, a serine hydrolase inhibitor, methoxy-arachidonyl fluorophosphate, was the most potent inhibitor of 2-AG metabolism by EPHX1 microsomes. These results demonstrate that 2-AG is an endogenous substrate for EPHX1, a potential role of EPHX1 in the endocannabinoid signaling and a new AA biosynthetic pathway. PMID:24958911

  4. MWCNTs-Reinforced Epoxidized Linseed Oil Plasticized Polylactic Acid Nanocomposite and Its Electroactive Shape Memory Behaviour

    PubMed Central

    Alam, Javed; Alam, Manawwer; Raja, Mohan; Abduljaleel, Zainularifeen; Dass, Lawrence Arockiasamy

    2014-01-01

    A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs) was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA) was first plasticized by epoxidized linseed oil (ELO) in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %), with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC), tensile test, and thermo gravimetric analysis (TGA). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME) in the resulting nanocomposite was investigated by a fold-deploy “U”-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices. PMID:25365179

  5. 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.

  6. Characterization of Polyimide Matrix Resins and Prepregs

    NASA Technical Reports Server (NTRS)

    Maximovich, M. G.; Galeos, R. M.

    1985-01-01

    Graphite/polyimide composite materials are attractive candidates for a wide range of aerospace applications. They have many of the virtues of graphite/epoxies, i.e., high specific strengths and stiffness, and also outstanding thermal/oxidative stability. Yet they are not widely used in the aerospace industry due to problems of procesability. By their nature, modern addition polyimide (PI) resins and prepregs are more complex than epoxies; the key to processing lies in characterizing and understanding the materials. Chemical and rheological characterizations are carried out on several addition polyimide resins and graphite reinforced prepregs, including those based on PMR-15, LARC 160 (AP 22), LARC 160 (Curithane 103) and V378A. The use of a high range torque transducer with a Rheometrics mechanical spectrometer allows rheological data to be generated on prepreg materials as well as neat resins. The use of prepreg samples instead of neat resins eliminates the need for preimidization of the samples and the data correlates well with processing behavior found in the shop. Rheological characterization of the resins and prepregs finds significant differences not readily detected by conventional chemical characterization techniques.

  7. Diffusion of residual monomer in polymer resins.

    PubMed Central

    Piver, W T

    1976-01-01

    A simplified mathematical model which made use of Fick's laws of diffusion written in spherical coordinates was developed to describe the rate of diffusion of residual monomers from polymer resins. The properties of the monomer-polymer system which influenced the amount of monomer remaining in the polymer as a function of time were the diffusivity and solubility of the monomer in the polymer, and the particle size of the polymer resin. This model was used to analyze literature data on the diffusion of residual vinyl chloride monomer in polyvinyl chloride resins made by the suspension process. It was concluded that particle size of the resin was a significant parameter which should be taken advantage of in process equipment designed to remove residual monomer from PVC resins. The diffusivity of the monomer in the polymer was a function of the solubility of the monomer in the polymer. Monomer solubility can be determined from Henry's law. It was suggested that this model could be adapted to describe diffusion of monomers from any monomer-polymer system, and would be a useful approach to modeling the transport of nonreactive chemical additives from plastics. PMID:1026410

  8. 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

  9. Water transport into epoxy resins and composites

    SciTech Connect

    Tsou, H.S.

    1987-01-01

    The processing-property relationships were established for the epoxy system of tetraglycidyl 4,4'-diaminodiphenyl methane (TGDDM) cured with diaminodiphenyl sulfone (DDS). The TGDDM-DDS epoxy system was selected for analysis as the ensuing polymer matrix is most common in high-performance fiber-reinforced epoxy composites. Experiments on water transport in epoxy resins with varying compositions were performed and a relaxation-coupled transport behavior was observed in these epoxy resins. By post-curing vitrified epoxy resins, the additional free volume usually measured in them was removed and maximum water uptake was reduced. Since epoxy resins were in a quasi-equilibrium glassy state after the post-cure, Fick's law with a constant diffusion coefficient could adequately describe the water sorption behavior. A network formation model based on the branching theory was developed, taking into account the difference in reactivities of primary and secondary amines and the etherification reaction. Using this network formation model, water uptake in post-cured epoxy resins was found to be proportional to tertiary amine concentration.

  10. Development of a heterogeneous laminating resin system

    NASA Technical Reports Server (NTRS)

    Biermann, T. F.; Hopper, L. C.

    1985-01-01

    The factors which effect the impact resistance of laminating resin systems and yet retain equivalent performance with the conventional 450 K curing epoxy matrix systems in other areas were studied. Formulation work was conducted on two systems, an all-epoxy and an epoxy/bismaleimide, to gain fundamental information on the effect formulation changes have upon neat resin and composite properties. The all-epoxy work involved formulations with various amounts and combinations of eight different epoxy resins, four different hardeners, fifteen different toughening agents, a filler, and a catalyst. The epoxy/bismaleimide effort improved formulations with various amounts and combinations of nine different resins, four different hardeners, eight different toughening agents, four different catalysts, and a filler. When a formulation appeared to offer the proper combination of properties required for a laminating resin Celion 3K-70P fabric was prepregged. Initial screening tests on composites primarily involved Gardner type impact and measurement of short beam shear strengths under dry and hot/wet conditions.

  11. Biocompatibility of polymethylmethacrylate resins used in dentistry.

    PubMed

    Gautam, Rupali; Singh, Raghuwar D; Sharma, Vinod P; Siddhartha, Ramashanker; Chand, Pooran; Kumar, Rakesh

    2012-07-01

    Biocompatibility or tissue compatibility describes the ability of a material to perform with an appropriate host response when applied as intended. Poly-methylmethacrylate (PMMA) based resins are most widely used resins in dentistry, especially in fabrication of dentures and orthodontic appliances. They are considered cytotoxic on account of leaching of various potential toxic substances, most common being residual monomer. Various in vitro and in vivo experiments and cell based studies conducted on acrylic based resins or their leached components have shown them to have cytotoxic effects. They can cause mucosal irritation and tissue sensitization. These studies are not only important to evaluate the long term clinical effect of these materials, but also help in further development of alternate resins. This article reviews information from scientific full articles, reviews, or abstracts published in dental literature, associated with biocompatibility of PMMA resins and it is leached out components. Published materials were searched in dental literature using general and specialist databases, like the PubMED database. PMID:22454327

  12. Color stability of composite resin cements.

    PubMed

    Smith, Darrell S; Vandewalle, Kraig S; Whisler, Gerry

    2011-01-01

    This study sought to determine the difference in color stability of resin cements after one year of storage in water. Three commercial resin cements (Nexus 3, Calibra, Variolink 2) were evaluated under three different curing conditions (photo-, dual-, and self-cure) over three storage time periods (3, 6, and 12 months). A plastic mold was used to prepare cylindrical specimens of each of the three resin cements. For the phototcured specimens, only the base component of the resin cement was cured. For the dual- and self-cure specimens, the base and catalyst of the cements were mixed according to the manufacturer's instructions, syringed into the mold, and either photocured as before (dual-cure) or allowed to chemically set (self-cure). The total amount of color change (delta E) was calculated using a spectrophotometer after 24 hours (baseline) and after 3, 6, and 12 months of storage in distilled water. Data were analyzed using a repeated measures ANOVA and a Tukey test. After one year of storage, Nexus 3 demonstated the lowest color change values (delta E) under all curing conditions, although it was not significantly different from Variolink 2 when photocured or Calibra when self-cured. New resin cements without a traditional benzoyl peroxide/amine redox initiator system, such as Nexus 3, could be more color-stable over time. PMID:22313825

  13. Theoretical investigation of the mechanism for the cycloaddition of CO2 to epoxides catalyzed by a magnesium(II) porphyrin complex.

    PubMed

    Wang, Qin; Guo, Cai-Hong; Jia, Jianfeng; Wu, Hai-Shun

    2015-07-01

    The cycloaddition of CO2 to epoxides, catalyzed by Mg(TPP)/TBAI (TPP = tetraphenylporphyrin; TBAI = tetrabutylammonium iodide), was investigated using DFT methods. Epoxides with various substituents were studied to explore steric and electronic effects on the reaction mechanism. Computational results show that the cycloaddition proceeds according to a much easier mechanism in the presence of Mg(TPP) and TBAI than the mechanism that takes place when Mg(TPP) is used as the catalyst. A preference for the epoxide ring-opening to occur at the methine (Cα) or methylene (Cβ) carbon was noted. The ring-closing step leading to the formation of a five-membered carbonate is predicted to determine the reaction rate. For alkyl-substituted epoxides, the β pathway is favorable since steric factors are dominant; for epoxides with a strongly electron-donating group and styrene oxide, the reaction is mainly controlled by electronic factors and proceeds along the α pathway. When the epoxide has a strongly electron-withdrawing group (CF3), both steric and electronic effects play important roles. The calculated reactivity of epoxides with CO2 catalyzed by Mg(TPP)/TBAI is in good agreement with that observed experimentally. PMID:26113116

  14. THE SOLUBLE EPOXIDE HYDROLASE GENE HARBORS SEQUENCE VARIATIONS ASSOCIATED WITH SUSCEPTIBILITY TO AND PROTECTION FROM INCIDENT ISCHEMIC STROKE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stroke is the leading cause of severe disability and the third leading cause of death, accounting for one of every 15 deaths in the USA. We investigated the association of polymorphisms in the soluble epoxide hydrolase gene (EPHX2) with incident ischemic stroke in African-Americans and Whites. Twelv...

  15. 40 CFR 63.1427 - Process vent requirements for processes using extended cookout as an epoxide emission reduction...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 12 2014-07-01 2014-07-01 false Process vent requirements for processes using extended cookout as an epoxide emission reduction technique. 63.1427 Section 63.1427 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS...

  16. Enantioselective ring-opening of meso-epoxides by aromatic amines catalyzed by a homochiral metal-organic framework.

    PubMed

    Regati, Sridhar; He, Yabing; Thimmaiah, Muralidhara; Li, Peng; Xiang, Shengchang; Chen, Banglin; Zhao, John Cong-Gui

    2013-10-28

    The enantioselective ring-opening of meso-epoxides by aromatic amines was achieved by using a new chiral metal-organic framework . The corresponding α-hydroxyamines were obtained with good yields and ee values (up to 89% ee). PMID:24030658

  17. Ingestion of the epoxide hydrolase inhibitor AUDA modulates immune responses of the mosquito, Culex quinquefasciatus during blood feeding.

    PubMed

    Xu, Jiawen; Morisseau, Christophe; Yang, Jun; Lee, Kin Sing Stephen; Kamita, Shizuo G; Hammock, Bruce D

    2016-09-01

    Epoxide hydrolases (EHs) are enzymes that play roles in metabolizing xenobiotic epoxides from the environment, and in regulating lipid signaling molecules, such as juvenile hormones in insects and epoxy fatty acids in mammals. In this study we fed mosquitoes with an epoxide hydrolase inhibitor AUDA during artificial blood feeding, and we found the inhibitor increased the concentration of epoxy fatty acids in the midgut of female mosquitoes. We also observed ingestion of AUDA triggered early expression of defensin A, cecropin A and cecropin B2 at 6 h after blood feeding. The expression of cecropin B1 and gambicin were not changed more than two fold compared to controls. The changes in gene expression were transient possibly because more than 99% of the inhibitor was metabolized or excreted at 42 h after being ingested. The ingestion of AUDA also affected the growth of bacteria colonizing in the midgut, but did not affect mosquito longevity, fecundity and fertility in our laboratory conditions. When spiked into the blood, EpOMEs and DiHOMEs were as effective as the inhibitor AUDA in reducing the bacterial load in the midgut, while EETs rescued the effects of AUDA. Our data suggest that epoxy fatty acids from host blood are immune response regulators metabolized by epoxide hydrolases in the midgut of female mosquitoes, inhibition of which causes transient changes in immune responses, and affects growth of microbes in the midgut. PMID:27369469

  18. 40 CFR 63.1427 - Process vent requirements for processes using extended cookout as an epoxide emission reduction...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 12 2013-07-01 2013-07-01 false Process vent requirements for processes using extended cookout as an epoxide emission reduction technique. 63.1427 Section 63.1427 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS...

  19. 3-D QSAR ANALYSIS OF INHIBITION OF MURINE SOLUBLE EPOXIDE HYDROLASE (MSEH) BY BENZOYLUREAS, ARYLUREAS, AND THEIR ANALOGUES. (R825433)

    EPA Science Inventory

    Two hundred and seventy-one compounds including benzoylureas, arylureas and related compounds were assayed using recombinant murine soluble epoxide hydrolase (MsEH) produced from a baculovirus expression system. Among all the insect growth regulators assayed, 18 benzoylphenylu...

  20. Efficient alkene epoxidation catalyzed by molybdenyl acetylacetonate supported on aminated UiO-66 metal−organic framework

    SciTech Connect

    Kardanpour, Reihaneh; Tangestaninejad, Shahram; Mirkhani, Valiollah; Moghadam, Majid; Mohammadpoor-Baltork, Iraj; Zadehahmadi, Farnaz

    2015-03-15

    Metal–organic frameworks (MOFs) containing Mo Schiff base complexes were prepared by post-synthesis method and applied as efficient catalysts in the epoxidation of alkenes with tert-BuOOH. In this manner, UiO-66-NH{sub 2} (UiO=University of Oslo) MOF was reacted with salicylaldehyde and thiophene-2-carbaldehyde to produce bidentate Schiff bases. Then, the Schiff base ligands were used for immobilization of molybdenyl acetylacetonate. These new catalysts were characterized by FT-IR, UV–vis spectroscopic techniques, X-ray diffraction (XRD), BET, inductively coupled plasma atomic emission spectroscopy (ICP-AES) and field emission scanning electron microscopy (FE-SEM). These catalytic systems showed excellent activity in the epoxidation of alkenes such as cyclic and linear ones with tert-butyl hydroperoxide (TBHP) in 1,2-dichloroethane, and reused several times without any appreciable loss of their activity. - Graphical abstract: Efficient alkene epoxidation with TBHP catalyzed by heterogeneous and reusable molybdenum base catalysts is reported. - Highlights: • UiO-66-NH{sub 2} was modified with salicylaldehyde and thiophene-2-carbaldehyde. • The Schiff base groups were used for immobilization of MoO{sub 2}(acac){sub 2}. • The heterogeneous catalysts were prepared. • The prepared catalysts were used for epoxidation of alkenes. • Compared to other catalyst, our catalysts were more efficient and forceful.

  1. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Modified reaction products of alkyl... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10145 Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

  2. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Modified reaction products of alkyl... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10145 Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

  3. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Modified reaction products of alkyl... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10145 Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

  4. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Modified reaction products of alkyl... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10145 Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

  5. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified reaction products of alkyl... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10145 Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

  6. SYNTHESIS OF TETRAHYDROPYRAN DERIVATIVES VIA A NOVEL INDIUM TRICHLORIDE MEDIATED CROSS-CYCLIZATION BETWEEN EPOXIDES AND HOMOALLYL ALCOHOLS. (R822668)

    EPA Science Inventory

    Abstract

    A cross-cyclization between epoxides and homoallyl alcohols catalyzed by indium chloride generates tetrahydropyran derivatives in high yields.

    Graphical Abstract


    INVESTIGATION OF THE SURFACE PROPERTIES OF POLYMERIC SOAPS OBTAINED BY RING-OPENING POLYMERIZATION OF EPOXIDIZED SOYBEAN OIL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Epoxidized soybean oil (ESO) was converted to a polysoap via a two-step synthetic procedure of catalytic ring-opening polymerization (PESO), followed by hydrolysis with a base (HPESO). Various molecular weights of PESO and HPESO were prepared by varying the reaction temperature and/or catalyst conc...

  7. Expression and characterization of styrene monooxygenases of Rhodococcus sp. ST-5 and ST-10 for synthesizing enantiopure (S)-epoxides.

    PubMed

    Toda, Hiroshi; Imae, Ryouta; Komio, Tomoko; Itoh, Nobuya

    2012-10-01

    Styrene monooxygenase (StyA, SMOA)- and flavin oxidoreductase (StyB, SMOB)-coding genes of styrene-assimilating bacteria Rhodococcus sp. ST-5 and ST-10 were successfully expressed in Escherichia coli. Determined amino acid sequences of StyAs and StyBs of ST-5 and ST-10 showed more similarity with those of Pseudomonas than with self-sufficient styrene monooxygenase (StyA2B) of Rhodococcus. Recombinant enzymes were purified from E. coli cells as functional proteins, and their properties were characterized in detail. StyBs (flavin oxidoreductase) of strains ST-5 and ST-10 have similar enzymatic properties to those of Pseudomonas, but StyB of strain ST-10 exhibited higher temperature stability than that of strain ST-5. StyAs of strains ST-5 and ST-10 catalyzed the epoxidation of vinyl side-chain of styrene and its derivatives and produced (S)-epoxides from styrene derivatives and showed high stereoselectivity. Both StyAs showed higher specific activity on halogenated styrene derivatives than on styrene itself. Additionally, the enzymes could catalyze the epoxidation of short-chain 1-alkenes to the corresponding (S)-epoxides. Aromatic compounds including styrene, 3-chlorostyrene, styrene oxide, and benzene exhibited marked inhibition of SMO reaction, although linear 1-alkene showed no inhibition of SMO activity at any concentration. PMID:22258641

  8. Ponderosa pine resin defenses and growth: metrics matter.

    PubMed

    Hood, Sharon; Sala, Anna

    2015-11-01

    Bark beetles (Coleoptera: Curculionidae, Scolytinae) cause widespread tree mortality in coniferous forests worldwide. Constitutive and induced host defenses are important factors in an individual tree's ability to survive an attack and in bottom-up regulation of bark beetle population dynamics, yet quantifying defense levels is often difficult. For example, in Pinus spp., resin flow is important for resistance to bark beetles but is extremely variable among individuals and within a season. While resin is produced and stored in resin ducts, the specific resin duct metrics that best correlate with resin flow remain unclear. The ability and timing of some pine species to produce induced resin is also not well understood. We investigated (i) the relationships between ponderosa pine (Pinus ponderosa Lawson & C. Lawson) resin flow and axial resin duct characteristics, tree growth and physiological variables, and (ii) if mechanical wounding induces ponderosa pine resin flow and resin ducts in the absence of bark beetles. Resin flow increased later in the growing season under moderate water stress and was highest in faster growing trees. The best predictors of resin flow were nonstandardized measures of resin ducts, resin duct size and total resin duct area, both of which increased with tree growth. However, while faster growing trees tended to produce more resin, models of resin flow using only tree growth were not statistically significant. Further, the standardized measures of resin ducts, density and duct area relative to xylem area, decreased with tree growth rate, indicating that slower growing trees invested more in resin duct defenses per unit area of radial growth, despite a tendency to produce less resin overall. We also found that mechanical wounding induced ponderosa pine defenses, but this response was slow. Resin flow increased after 28 days, and resin duct production did not increase until the following year. These slow induced responses may allow

  9. Modeling of Toxicity-Relevant Electrophilic Reactivity for Guanine with Epoxides: Estimating the Hard and Soft Acids and Bases (HSAB) Parameter as a Predictor.

    PubMed

    Zhang, Jing; Wang, Chenchen; Ji, Li; Liu, Weiping

    2016-05-16

    According to the electrophilic theory in toxicology, many chemical carcinogens in the environment and/or their active metabolites are electrophiles that exert their effects by forming covalent bonds with nucleophilic DNA centers. The theory of hard and soft acids and bases (HSAB), which states that a toxic electrophile reacts preferentially with a biological macromolecule that has a similar hardness or softness, clarifies the underlying chemistry involved in this critical event. Epoxides are hard electrophiles that are produced endogenously by the enzymatic oxidation of parent chemicals (e.g., alkenes and PAHs). Epoxide ring opening proceeds through a SN2-type mechanism with hard nucleophile DNA sites as the major facilitators of toxic effects. Thus, the quantitative prediction of chemical reactivity would enable a predictive assessment of the molecular potential to exert electrophile-mediated toxicity. In this study, we calculated the activation energies for reactions between epoxides and the guanine N7 site for a diverse set of epoxides, including aliphatic epoxides, substituted styrene oxides, and PAH epoxides, using a state-of-the-art density functional theory (DFT) method. It is worth noting that these activation energies for diverse epoxides can be further predicted by quantum chemically calculated nucleophilic indices from HSAB theory, which is a less computationally demanding method than the exacting procedure for locating the transition state. More importantly, the good qualitative/quantitative correlations between the chemical reactivity of epoxides and their bioactivity suggest that the developed model based on HSAB theory may aid in the predictive hazard evaluation of epoxides, enabling the early identification of mutagenicity/carcinogenicity-relevant SN2 reactivity. PMID:26929981

  10. [Application of composite resin inlays to deciduous molars--a clinical observation of the resin onlay].

    PubMed

    Yamamoto, H; Iyori, H; Kanomi, R; Yao, K; Hieda, T

    1990-01-01

    Although composite resin has been used as an aesthetic restorative material, wear and fracture of the resin of fracture of the tooth structure are likely to occur when the size of the dental cavities are large. In addition to the lack of the aesthetic value, clinical results of prefabricated metal crown revealed several problems which were caused by the wear of the metal and the ill-adaptation of the cervical margin. In the present study, 50 devitalized deciduous molars were treated with composite resin onlays which were designed to cover the entire occlusal surface of the deciduous molar, and the clinical results were evaluated for a 6 month period. Additionally, for the purpose of simplification of the laboratory process for making resin onlays, ready-made occlusal shells were fabricated. The variety of the prepared shell size consisted of 7 sizes for the first deciduous molar, 9 sizes for the upper second deciduous molar and 10 sizes for the lower deciduous molar. The following results were obtained. 1) A partial resin fracture at the peripheral area of the mesio-buccal cuspid was found in five cases out of 50. 2) A glossy appearance on the surface of the onlay which was created by coated unfilled resin disappeared after 6 months of observation. 3) In relation to the resin onlay, when the antagonistic tooth was restored with prefabricated metal crowns, holes were made by attrition on all the crowns within a 3-4 month period.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2133972

  11. Composite resin in medicine and dentistry.

    PubMed

    Stein, Pamela S; Sullivan, Jennifer; Haubenreich, James E; Osborne, Paul B

    2005-01-01

    Composite resin has been used for nearly 50 years as a restorative material in dentistry. Use of this material has recently increased as a result of consumer demands for esthetic restorations, coupled with the public's concern with mercury-containing dental amalgam. Composite is now used in over 95% of all anterior teeth direct restorations and in 50% of all posterior teeth direct restorations. Carbon fiber reinforced composites have been developed for use as dental implants. In medicine, fiber-reinforced composites have been used in orthopedics as implants, osseous screws, and bearing surfaces. In addition, hydroxyapatite composite resin has become a promising alternative to acrylic cement in stabilizing fractures and cancellous screw fixation in elderly and osteoporotic patients. The use of composite resin in dentistry and medicine will be the focus of this review, with particular attention paid to its physical properties, chemical composition, clinical applications, and biocompatibility. PMID:16393132

  12. Jetted mixtures of particle suspensions and resins

    NASA Astrophysics Data System (ADS)

    Hoath, S. D.; Hsiao, W.-K.; Hutchings, I. M.; Tuladhar, T. R.

    2014-10-01

    Drop-on-demand (DoD) ink-jetting of hard particle suspensions with volume fraction Φ ˜ 0.25 has been surveyed using 1000 ultra-high speed videos as a function of particle size (d90 = 0.8—3.6 μm), with added 2 wt. % acrylic (250 kDa) or 0.5 wt. % cellulose (370 kDa) resin, and also compared with Newtonian analogues. Jet break-off times from 80 μm diameter nozzles were insensitive (120 ± 10 μs) to particle size, and resin jet break-off times were not significantly altered by >30 wt. % added particles. Different particle size grades can be jetted equally well in practice, while resin content effectively controls DoD break-off times.

  13. Improved high temperature resistant matrix resins

    NASA Technical Reports Server (NTRS)

    Chang, G. E.; Powell, S. H.; Jones, R. J.

    1983-01-01

    The objective was to develop organic matrix resins suitable for service at temperatures up to 644 K (700 F) and at air pressures up to 0.4 MPa (60 psia) for time durations of a minimum of 100 hours. Matrix resins capable of withstanding these extreme oxidative environmental conditions would lead to increased use of polymer matrix composites in aircraft engines and provide significant weight and cost savings. Six linear condensation, aromatic/heterocyclic polymers containing fluorinated and/or diphenyl linkages were synthesized. The thermo-oxidative stability of the resins was determined at 644 K and compressed air pressures up to 0.4 MPa. Two formulations, both containing perfluoroisopropylidene linkages in the polymer backbone structure, exhibited potential for 644 K service to meet the program objectives. Two other formulations could not be fabricated into compression molded zero defect specimens.

  14. Determination by gas-liquid chromatography of trace amounts of soft polyvinyl chloride plastic additives in aqueous solutions. I. Epoxidized vegetable oils.

    PubMed

    Smistad, G; Waaler, T; Roksvaag, P O

    1989-01-01

    A gas-liquid chromatographic method for the determination of epoxidized vegetable oils (EVO), such as epoxidized soybean oil and epoxidized linseed oil, in aqueous solutions is described. The EVOs are extracted with n-hexane and transesterified to the methyl esters by sodium methoxide in methanol. 3% OV-210 is used as the stationary phase. The weakest standard solution corresponds to 5 micrograms/l (5 ppb) of EVO in an aqueous sample. The reproducibility of a single analysis is 5%. The method is used for the determination of EVO in intravenous fluids stored in flexible polyvinyl chloride bags. PMID:2597333

  15. Development of Highly Active and Regioselective Catalysts for the Copolymerization of Epoxides with Cyclic Anhydrides: An Unanticipated Effect of Electronic Variation.

    PubMed

    DiCiccio, Angela M; Longo, Julie M; Rodríguez-Calero, Gabriel G; Coates, Geoffrey W

    2016-06-01

    Recent developments in polyester synthesis have established several systems based on zinc, chromium, cobalt, and aluminum catalysts for the ring-opening alternating copolymerization of epoxides with cyclic anhydrides. However, to date, regioselective processes for this copolymerization have remained relatively unexplored. Herein we report the development of a highly active, regioselective system for the copolymerization of a variety of terminal epoxides and cyclic anhydrides. Unexpectedly, electron withdrawing substituents on the salen framework resulted in a more redox stable Co(III) species and longer catalyst lifetime. Using enantiopure propylene oxide, we synthesized semicrystalline polyesters via the copolymerization of a range of epoxide/anhydride monomer pairs. PMID:27171536

  16. BENZO[a]PYRENE DIOL EPOXIDE PERTURBATION OF CELL CYCLE KINETICS OF SYNCHRONIZED MOUSE LIVER EPITHELIAL CELLS

    SciTech Connect

    Pearlman, A.L.; Navsky, B.N.; Bartholomew, J.C

    1980-07-01

    A cell cycle synchronization system is described for the analysis of the perturbation of cell cycle kinetics and the cycle-phase specificity of chemicals and other agents. We used the system to study the effects of ({+-})r-7, t-8-dihydroxy-t-9, 10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BaP diol epoxide) upon the cell cycle of mouse liver epithelial cells(NMuLi). BaP diol epoxide(0.6 uM) was added to replated cultures of NMuLi cells that had been synchronized in various stages of the cell cycle by centrifugal elutriation. DNA histograms were obtained by flow cytometry as a function of time after replating. The data were analyzed by a computer modeling routine and reduced to a few graphs illustrating the 'net effects' of the BaP diol epoxide relative to controls. BaP diol epoxide slowed S-phase traversal in all samples relative to their respective control. Traversal through G{sub 2}M was also slowed by at least 50%. BaP diol epoxide had no apparent effect upon G{sub 1} traversal by cycling cells, but delayed the recruitment of quiescent G{sub 0} cells by about 2 hrs. The methods described constitute a powerful new approach for probing the cell cycle effects of a wide variety of agents. The present system appears to be extremely sensitive and capable of characterizing the action of agents on each phase of the cell cycle. The methods are automatable and would allow for the assay and possible differential characterization of mutagens and carcinogens.

  17. Cytochrome P450-type hydroxylation and epoxidation in a tyrosine-liganded hemoprotein, catalase-related allene oxide synthase.

    PubMed

    Boeglin, William E; Brash, Alan R

    2012-07-13

    The ability of hemoproteins to catalyze epoxidation or hydroxylation reactions is usually associated with a cysteine as the proximal ligand to the heme, as in cytochrome P450 or nitric oxide synthase. Catalase-related allene oxide synthase (cAOS) from the coral Plexaura homomalla, like catalase itself, has tyrosine as the proximal heme ligand. Its natural reaction is to convert 8R-hydroperoxy-eicosatetraenoic acid (8R-HPETE) to an allene epoxide, a reaction activated by the ferric heme, forming product via the Fe(IV)-OH intermediate, Compound II. Here we oxidized cAOS to Compound I (Fe(V)=O) using the oxygen donor iodosylbenzene and investigated the catalytic competence of the enzyme. 8R-hydroxyeicosatetraenoic acid (8R-HETE), the hydroxy analog of the natural substrate, normally unreactive with cAOS, was thereby epoxidized stereospecifically on the 9,10 double bond to form 8R-hydroxy-9R,10R-trans-epoxy-eicosa-5Z,11Z,14Z-trienoic acid as the predominant product; the turnover was 1/s using 100 μm iodosylbenzene. The enantiomer, 8S-HETE, was epoxidized stereospecifically, although with less regiospecificity, and was hydroxylated on the 13- and 16-carbons. Arachidonic acid was converted to two major products, 8R-HETE and 8R,9S-eicosatrienoic acid (8R,9S-EET), plus other chiral monoepoxides and bis-allylic 10S-HETE. Linoleic acid was epoxidized, whereas stearic acid was not metabolized. We conclude that when cAOS is charged with an oxygen donor, it can act as a stereospecific monooxygenase. Our results indicate that in the tyrosine-liganded cAOS, a catalase-related hemoprotein in which a polyunsaturated fatty acid can enter the active site, the enzyme has the potential to mimic the activities of typical P450 epoxygenases and some capabilities of P450 hydroxylases. PMID:22628547

  18. Reaction Mechanism for Direct Propylene Epoxidation by Alumina-Supported Silver Aggregates. The Role of the Particle / Support Interface

    SciTech Connect

    Cheng, Lei; Yin, Chunrong; Mehmood, Faisal; Liu, Bin; Greeley, Jeffrey P.; Lee, Sungsik; Lee, Byeongdu; Seifert, Soenke; Winans, R. E.; Teschner, D.; Schlogl, Robert; Vajda, S.; Curtiss, Larry A.

    2013-11-21

    Sub-nanometer Ag aggregates on alumina supports have been found to be active toward direct propylene epoxidation to propylene oxide by molecular oxygen at low temperatures, with a negligible amount of carbon dioxide formation (Science 328, p. 224, 2010). In this work, we computationally and experimentally investigate the origin of the high reactivity of the sub-nanometer Ag aggregates. Computationally, we study O2 dissociation and propylene epoxidation on unsupported Ag19 and Ag20 clusters, as well as alumina-supported Ag19. The O2 dissociation and propylene epoxidation apparent barriers at the interface between the Ag aggregate and the alumina support are calculated to be 0.2 and 0.2~0.4 eV, respectively. These barriers are somewhat lower than those on sites away from the interface. The mechanism at the interface is similar to what was previously found for the silver trimer on alumina and can account for the high activity observed for the direct oxidation of propylene on the Ag aggregates. The barriers for oxygen dissociation on these model systems both at the interface and on the surfaces are small compared to crystalline surfaces, indicating that availability of oxygen will not be a rate limiting step for the aggregates, as in the case of the crystalline surfaces. Experimentally, we investigate Ultrananocrystalline Diamond (UNCD)-supported silver aggregates under reactive conditions of propylene partial oxidation. The UNCD-supported Ag clusters are found to be not measurably active toward propylene oxidation, in contrast to the alumina supported Ag clusters. This suggests that the lack of metal-oxide interfacial sites of the Ag-UNCD catalyst, limits the epoxidation catalytic activity. This combined computational and experimental study shows the importance of the metal-oxide interface as well as the non-crystalline nature of the alumina-supported sub-nanometer Ag aggregate catalysts for propylene epoxidation.

  19. Resin additive improves performance of high-temperature hydrocarbon lubricants

    NASA Technical Reports Server (NTRS)

    Johnson, R. L.; Loomis, W. R.

    1971-01-01

    Paraffinic resins, in high temperature applications, improve strength of thin lubricant film in Hertzian contacts even though they do not increase bulk oil viscosity. Use of resin circumvents corrosivity and high volatility problems inherent with many chemical additives.

  1. REDFORD CORE MAKING MACHINE. RESIN IMPREGNATED SAND IS BLOWN INTO ...

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

    REDFORD CORE MAKING MACHINE. RESIN IMPREGNATED SAND IS BLOWN INTO THE HEATED CORE BOX THAT SETS THE RESIN CREATING THE HARDENED CORE SHOWN HERE. - Southern Ductile Casting Company, Core Making, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  2. Try-in Pastes Versus Resin Cements: A Color Comparison.

    PubMed

    Vaz, Edenize Cristina; Vaz, Maysa Magalhães; Rodrigues Gonçalves de Oliveira, Maria Beatriz; Takano, Alfa Emília; de Carvalho Cardoso, Paula; de Torres, Érica Miranda; Gonzaga Lopes, Lawrence

    2016-05-01

    This study aimed to compare the color of ceramic veneer restorations using different shades of try-in pastes and resin cement. Researchers found no differences between try-in pastes and resin cements after cementation. PMID:27213935

  3. Additive effects on the toughening of unsaturated polyester resins

    SciTech Connect

    Suspene, L.; Yang, Y.S.; Pascault, J.P.

    1993-12-31

    An elastomer additive, carboxy-terminated acrylonitrile-butadiene copolymer, was used for toughening in the free radical cross-linking copolymerization of unsaturated polyester (UP) resins. For molded parts, Charpy impact behavior was generally enhanced and the number of catastrophic failures was reduced. The miscibility and interfacial properties of additive and resin blends play important roles in the toughening process. Phase-diagram studies showed that the elastomer additive is immiscible with the UP resin and is phase-separated from the resin matrix during curing. This phase-separation phenomenon is similar to that in the low-profile mechanism of UP resins. Additive-resin system miscibility greatly influences curing morphology. Microvoids occurred in the additive phase of cured resin because of shrinkage stress. The intrinsic inhomogeneity of the polyester network and the existence of microvoids in the final product limit the toughening effect of additives on unsaturated polyester resins. 49 refs., 13 figs., 3 tabs.

  4. Effect of resin monomer composition on toothbrush wear resistance.

    PubMed

    Kawai, K; Iwami, Y; Ebisu, S

    1998-04-01

    The purpose of this study was to compare the toothbrush abrasion resistance of seven different experimental resins which were made by changing the composition of resin monomers. The experimental resins were made by mixing four kinds of dental resin monomers (Bis-GMA, UDMA, TMPT and TEGDMA), camphorquinone (1 wt%), dimethylaminoethyl methacrylate (2 wt%) and 2,6-di-tert-butyl-p-cresol (0.05 wt%). The resin specimens were stored in air for 2 weeks, and then put on a toothbrush abrasion testing machine. After 100000 strokes, the wear loss of each specimen was determined by weight change during the wear test. TMPT-TEGDMA resin showed the most wear resistance, while Bis-GMA- and UDMA-based resins showed increased wear resistance with an increased content of TEGDMA. Also, a inverse relationship between the microhardness number and the amount of wear of the respective resins was confirmed. PMID:9610853

  5. Performance Properties of Graphite Reinforced Composites with Advanced Resin Matrices

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.

    1980-01-01

    This article looks at the effect of different resin matrices on thermal and mechanical properties of graphite composites, and relates the thermal and flammability properties to the anaerobic char yield of the resins. The processing parameters of graphite composites utilizing graphite fabric and epoxy or other advanced resins as matrices are presented. Thermoset resin matrices studied were: aminecured polyfunctional glycidyl aminetype epoxy (baseline), phenolicnovolac resin based on condensation of dihydroxymethyl-xylene and phenol cured with hexamine, two types of polydismaleimide resins, phenolic resin, and benzyl resin. The thermoplastic matrices studied were polyethersulfone and polyphenylenesulfone. Properties evaluated in the study included anaerobic char yield, limiting oxygen index, smoke evolution, moisture absorption, and mechanical properties at elevated temperatures including tensile, compressive, and short-beam shear strengths. Generally, it was determined that graphite composites with the highest char yield exhibited optimum fire-resistant properties.

  6. Standard tests for toughened resin composites, revised edition

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Several toughened resin systems are evaluated to achieve commonality for certain kinds of tests used to characterize toughened resin composites. Specifications for five tests were standardized; these test standards are described.

  7. PMR Resin Compositions For High Temperatures

    NASA Technical Reports Server (NTRS)

    Vannucci, Raymond D.

    1989-01-01

    Report describes experiments to identify polymer matrix resins suitable for making graphite-fiber laminates used at 700 degree F (371 degree C) in such applications as aircraft engines to achieve higher thrust-to-weight ratios. Two particular high-molecular-weight formulations of PMR (polymerization of monomer reactants) resins most promising. PMR compositions of higher FMW exhibit enhanced thermo-oxidative stability. Formation of high-quality laminates with these compositions requires use of curing pressures higher than those suitable for compositions of lower FMW.

  8. Electronic structure and optical properties of resin

    NASA Astrophysics Data System (ADS)

    Rao, Zhi-Fan; Zhou, Rong-Feng

    2013-03-01

    We used the density of functional theory (DFT) to study the electronic structure and density of states of resin by ab initio calculation. The results show the band gap of resin is 1.7 eV. The covalent bond is combined C/O atoms with H atoms. The O 2p orbital is the biggest effect near the Fermi level. The results of optical properties show the reflectivity is low, and the refractive index is 1.7 in visible light range. The highest absorption coefficient peak is in 490 nm and the value is 75,000.

  9. New phosphorus-containing bisimide resins

    NASA Technical Reports Server (NTRS)

    Varma, I. K.; Fohlen, G. M.; Hsu, M.-T.; Parker, J. A.

    1984-01-01

    Phosphorus-based flame retardants have been effectively used in a wide variety of polymeric materials. Such additives, however, may either influence the decomposition reaction in polymers or lack durability due to a tendency to be leached out by solvents. Attention is given to the synthesis, characterization, thermal stability and degradation mechanisms of bisimide resins, and an evaluation is conducted of the flammability and mechanical properties of graphite cloth-reinforced laminates fabricated from one of the six phosphorus-containing bisimide resins considered.

  10. Resin transfer molding of textile composites

    NASA Technical Reports Server (NTRS)

    Falcone, Anthony; Dursch, Harry; Nelson, Karl; Avery, William

    1993-01-01

    The design and manufacture of textile composite panels, tubes, and angle sections that were provided to NASA for testing and evaluation are documented. The textile preform designs and requirements were established by NASA in collaboration with Boeing and several vendors of textile reinforcements. The following four types of preform architectures were used: stitched uniweave, 2D-braids, 3D-braids, and interlock weaves. The preforms consisted primarily of Hercules AS4 carbon fiber; Shell RSL-1895 resin was introduced using a resin transfer molding process. All the finished parts were inspected using ultrasonics.

  11. Benzonorbornadiene end caps for PMR resins

    NASA Technical Reports Server (NTRS)

    Panigot, Michael J.; Waters, John F.; Varde, Uday; Sutter, James K.; Sukenik, Chaim N.

    1992-01-01

    Several ortho-disubstituted benzonorbornadiene derivatives are described. These molecules contain acid, ester, or anhydride functionality permitting their use as end caps in PMR (polymerization of monomer reactants) polyimide systems. The replacement of the currently used norbornenyl end caps with benzonorbornadienyl end caps affords resins of increased aromatic content. It also allows evaluation of some mechanistic aspects of PMR cross-linking. Initial testing of N-phenylimide model compounds and of actual resin formulations using the benzonorbornadienyl end cap reveals that they undergo efficient thermal crosslinking to give oligomers with physical properties and thermal stability comparable to commercial norbornene-end-capped PMR systems.

  12. Technical assessment for quality control of resins

    NASA Technical Reports Server (NTRS)

    Gosnell, R. B.

    1977-01-01

    Survey visits to companies involved in the manufacture and use of graphite-epoxy prepregs were conducted to assess the factors which may contribute to variability in the mechanical properties of graphite-epoxy composites. In particular, the purpose was to assess the contributions of the epoxy resins to variability. Companies represented three segments of the composites industry - aircraft manufacturers, prepreg manufacturers, and epoxy resin manufacturers. Several important sources of performance variability were identified from among the complete spectrum of potential sources which ranged from raw materials to composite test data interpretation.

  13. Resin Dermatitis in a Car Factory

    PubMed Central

    Engel, H. O.; Calnan, C. D.

    1966-01-01

    An outbreak of dermatitis in a car assembly factory is described; it affected 50 workers who handled rubber weatherstrips coated with an adhesive. The adhesive was found to contain para-tertiary butyl phenol (P.T.B.P.) formaldehyde resin. Of those patch tested 70% gave positive reactions to the adhesive and 65% to the resin. Improved methods of handling and personal protection succeeded in arresting the occurrence of dermatitis. Barrier creams gave no protection in these circumstances. The episode illustrates the different preventive control methods which have to be tried when dealing with a simple skin hazard which cannot be abolished. Images PMID:5904100

  14. Occupational dermatitis to epoxydic and phenolic resins.

    PubMed

    Geraut, Christian; Tripodi, Dominique; Brunet-Courtois, Béatrice; Leray, Fabrice; Geraut, Laurent

    2009-01-01

    Contact dermatitis to epoxydic and phenolic resins are the most frequent contact dermatoses due to plastics, in particular in the form of airborne dermatitis. The chemical formulas of the various components of these resins and their additives are complex and the patch tests available in the trade are insufficient and often arrive at a late stage in the progress of industry, in particular in advanced technologies like aeronautical engineering, shipbuilding or the new floor and wall coverings in buildings. This article is a review of the actions to be taken with these allergies, as well as with regards to their diagnosis, prevention and medico-legal compensation. PMID:19349256

  15. Method Development for the Determination of Diallyldimethylammonium Chloride at Trace Levels by Epoxidation Process.

    PubMed

    Mwangi, Isaac W; Ngila, J Catherine; Ndungu, Patrick; Msagati, Titus A M

    2013-01-01

    Domestic water is abstracted from its sources in raw form with a high content of dissolved and suspended material. Polydiallyldimethylammonium chloride (polyDADMAC) is a cationic polyelectrolyte used in the initial water clarification process. However, its residues in treated water pose a health risk as they react with chlorine to produce a carcinogenic compound. There is a need to determine the concentration of the polyelectrolyte cations that pass through the flocculation stage before the chlorine disinfection process in water treatment plants to ascertain the safety of water to consumers. The cationic polymer is UV inactive, and previously available methods for determining the concentrations of polyelectrolytes are unsatisfactory due to poor detection limits. This paper describes a UV-Visible (UV-vis) spectrophotometry method for the determination of residual polyDADMAC as an epoxide. The novelty method lies on the epoxidation of polyDADMAC using 20 % sodium hydroxide dissolved in 30 % hydrogen peroxide to produce a UV-Vis active compound. The epoxidation was confirmed by UV-Vis, FTIR and (1)H NMR techniques. Dilute solutions of varying concentrations of polyDADMAC (0.2-1.0 mg L(-1)) were treated with a basic solution of hydrogen peroxide then analysed by UV-Vis spectrophotometry. The wavelength at maximum absorption (λmax) was found to be 313 nm, and a linear calibration curve with a correlation coefficient (R (2)) of 0.993 was used for quantification purposes. The detection limit measured as three times the signal of the blank and was found to be 2.1 × 10(-4) mg L(-1). The method was applied to determine the concentration of polyDADMAC spiked in water samples collected from a pool as a model for environmental matrix. The results obtained agreed with the quantities spiked in the solution, thus qualified the method to be suitable for the determination of polyDADMAC in treated waters at trace levels. The method was also used to investigate the

  16. In vivo imaging of VMAT2 in pancreas using a 18F epoxide derivative of tetrabenazine

    PubMed Central

    Kung, Hank F.; Lieberman, Brian P.; Zhuang, Zhi-Ping; Oya, Shunichi; Kung, Mei-Ping; Choi, Seok Rye; Poessl, Karl; Blankemeyer, Eric; Hou, Catherine; Skovronsky, Daniel; Kilbourn, Michael

    2008-01-01

    Objectives Development of imaging agents for pancreatic beta cell mass may provide tools for studying insulin-secreting beta cells and their relationship with diabetes mellitus. In this paper a new imaging agent, [18F](+)-2-oxiranyl-3-isobutyl-9-(3-fluoropropoxy)-10-methoxy-2,3,4,6,7,11b-hexahydro-1H-pyrido[2,1-a]isoquinoline [18F](+)4, which displays properties targeting vesicular monoamine transporter 2 (VMAT2) binding sites of beta cells in the pancreas, was evaluated as a PET (positron emission tomography) agent for estimating beta cell mass in vivo. The hydrolyzable epoxide group of (+)4 may provide a mechanism for shifting biodistribution from liver to kidney thus, reducing the background signal. Methods Both 18F and 19F labeled (+) and (−) isomers of 4 were synthesized and evaluated. Organ distribution was carried out in normal rats. Uptake of [18F](+)4 in pancreas of normal rats was measured and correlated with blocking studies using competing drugs, (+)dihydrotetrabenazine, (+)-DTBZ or 9-fluoropropyl-(+)dihydro tetrabenazine (FP-(+)-DTBZ, (+)2). Results In vitro binding study of VMAT2 using rat brain striatum showed a Ki value of 0.08 and 0.15 nM for the (+)4 and (±)4, respectively. The in vivo biodistribution of [18F](+)4 in rats showed the highest uptake in the pancreas (2.68 %ID/g at 60 min post-injection). In vivo competition experiments with cold FP-(+)-DTBZ, (+)2, (3.5 mg/kg, 5 min iv pretreatment) led to a significant reduction of pancreas uptake (85 % blockade at 60 min). The inactive isomer [18F](−)4 showed significantly lower pancreas uptake (0.22 %ID/g at 30 min post-injection). Animal PET imaging studies of [18F](+)4 in normal rats demonstrated an avid pancreatic uptake in rats. Conclusion The preliminary results suggest that the epoxide, [18F](+)4, is highly selective in binding to VMAT2 and it has an excellent uptake in the pancreas of rats. The liver uptake was significantly reduced through the use of the epoxide group. Therefore, it

  17. Combination of natural fiber Boehmeria nivea (ramie) with matrix epoxide for bullet proof vest body armor

    NASA Astrophysics Data System (ADS)

    Anggoro, Didi Dwi; Kristiana, Nunung

    2015-12-01

    Ballistic protection equipment, such as a bulletproof vest, is a soldier's most important means of preserving life and survivability in extreme combat conditions. The bulletproof vests are designed to protect the user's chest from injury without disturbing the ability to perform his duties. Aromatic polyamide or aramid fibers known under the trade name Kevlar, Trawon and so is synthetic fiber materials commonly used in the manufacture of bulletproof vests. This synthetic fibers have high tensile strength and ductility. Kevlar is expensive and imported material. In this study, will introduce local natural raw materials, ramie fiber (Boehmeria nivea) which is cheaper and environmentally friendly. It has enough tenacity and tensile strength as a bulletproof vest. This experiment uses two panels, there are Panel A as front surface of Panel B. Panel A is a combination of ramie and epoxide matrix, while panel B is only ramie. From several variations of experimental combinations between Panel A and Panel B, optimal combination obtained with 16 layers of panel A and 31-34 layers of panel B which is able to protect againts cal. 7.65 mm × 17 mm (.32 ACP) bullet fired through pistol .32 Pindad from a distance of 20 meters. Panel with a size of 20 cm × 20 cm has a total thickness between 12,922 to13,745 mm and a total weight between 506,26 to 520,926gram. Scanning electron microscopy (SEM) observations indicated that the porosity and surface area of the ramie fiber is smooth, fiber surfaces showed topography with micropores. SEM also showed well-arranged structure of fibers bonding. Energy Dispersive X-ray (EDX) analysis indicated 100 % carbon contents in ramie fiber. Test result indicates that panel from composite ramie-epoxide can reach the level 1of International Standard of NIJ - 010104. Compared to panel from polyester fiber, the panel from composite ramie-epoxide (0,50-0,52 kg) is lighter weight than panel polyester fiber (1,642 kg).

  18. Combination of natural fiber Boehmeria nivea (ramie) with matrix epoxide for bullet proof vest body armor

    SciTech Connect

    Anggoro, Didi Dwi Kristiana, Nunung

    2015-12-29

    Ballistic protection equipment, such as a bulletproof vest, is a soldier’s most important means of preserving life and survivability in extreme combat conditions. The bulletproof vests are designed to protect the user’s chest from injury without disturbing the ability to perform his duties. Aromatic polyamide or aramid fibers known under the trade name Kevlar, Trawon and so is synthetic fiber materials commonly used in the manufacture of bulletproof vests. This synthetic fibers have high tensile strength and ductility. Kevlar is expensive and imported material. In this study, will introduce local natural raw materials, ramie fiber (Boehmeria nivea) which is cheaper and environmentally friendly. It has enough tenacity and tensile strength as a bulletproof vest. This experiment uses two panels, there are Panel A as front surface of Panel B. Panel A is a combination of ramie and epoxide matrix, while panel B is only ramie. From several variations of experimental combinations between Panel A and Panel B, optimal combination obtained with 16 layers of panel A and 31-34 layers of panel B which is able to protect againts cal. 7.65 mm × 17 mm (.32 ACP) bullet fired through pistol .32 Pindad from a distance of 20 meters. Panel with a size of 20 cm × 20 cm has a total thickness between 12,922 to13,745 mm and a total weight between 506,26 to 520,926gram. Scanning electron microscopy (SEM) observations indicated that the porosity and surface area of the ramie fiber is smooth, fiber surfaces showed topography with micropores. SEM also showed well-arranged structure of fibers bonding. Energy Dispersive X-ray (EDX) analysis indicated 100 % carbon contents in ramie fiber. Test result indicates that panel from composite ramie-epoxide can reach the level 1of International Standard of NIJ - 010104. Compared to panel from polyester fiber, the panel from composite ramie-epoxide (0,50-0,52 kg) is lighter weight than panel polyester fiber (1,642 kg)

  19. Synthesis, Characterization, and Cross-Linking Strategy of a Quercetin-Based Epoxidized Monomer as a Naturally-Derived Replacement for BPA in Epoxy Resins.

    PubMed

    Kristufek, Samantha L; Yang, Guozhen; Link, Lauren A; Rohde, Brian J; Robertson, Megan L; Wooley, Karen L

    2016-08-23

    The natural polyphenolic compound quercetin was functionalized and cross-linked to afford a robust epoxy network. Quercetin was selectively methylated and functionalized with glycidyl ether moieties using a microwave-assisted reaction on a gram scale to afford the desired monomer (Q). This quercetin-derived monomer was treated with nadic methyl anhydride (NMA) to obtain a cross-linked network (Q-NMA). The thermal and mechanical properties of this naturally derived network were compared to those of a conventional diglycidyl ether bisphenol A-derived counterpart (DGEBA-NMA). Q-NMA had similar thermal properties [i.e., glass transition (Tg ) and decomposition (Td ) temperatures] and comparable mechanical properties (i.e., Young's Modulus, storage modulus) to that of DGEBA-NMA. However, it had a lower tensile strength and higher flexural modulus at elevated temperatures. The application of naturally derived, sustainable compounds for the replacement of commercially available petrochemical-based epoxies is of great interest to reduce the environmental impact of these materials. Q-NMA is an attractive candidate for the replacement of bisphenol A-based epoxies in various specialty engineering applications. PMID:27415143

  20. 40 CFR 721.2752 - Epoxy resin containing phosphorus (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Epoxy resin containing phosphorus... Specific Chemical Substances § 721.2752 Epoxy resin containing phosphorus (generic). (a) Chemical substance... epoxy resin containing phosphorus (PMN P-00-912) is subject to reporting under this section for...