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Journal articles on the topic 'Epoxid'

Author: Grafiati

Published: 4 June 2021

Last updated: 3 February 2022

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1

Klemm, Elisabeth, Evelin Riesenberg, Hans-Heinrich Hörhold, and Rolf Märtin. "Photoinduzierte Spiroorthoester-Epoxid-Copolymerisation." Zeitschrift für Chemie 24, no. 11 (August 31, 2010): 412. http://dx.doi.org/10.1002/zfch.19840241112.

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2

Hörhold, H. H., and J. Klee. "Neue Copolymere — Untersuchungen zur Epoxid-Amin/Thiol-Additionspolymerisation. Unvernetzte Epoxid-Amin-Additionspolymere. 26." Acta Polymerica 40, no. 6 (June 1989): 421–22. http://dx.doi.org/10.1002/actp.1989.010400618.

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3

Hörhold, Hans-Heinrich, Joachim Klee, and Klaus Bellstedt. "Hochmolekulare lineare Epoxid-Amin-Additionspolymere." Zeitschrift für Chemie 22, no. 5 (August 31, 2010): 166–76. http://dx.doi.org/10.1002/zfch.19820220503.

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4

Klee, Joachim. "Unvernetzte epoxid-amin-additionspolymere, 27. Hybridnetzwerke — Möglichkeiten der carbonsäureanhydridmodifizierung und nachvernetzung von epoxid-amin-prepolymeren." Die Makromolekulare Chemie 190, no. 11 (November 1989): 2673–81. http://dx.doi.org/10.1002/macp.1989.021901101.

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5

Klee, Joachim, Hans-Heinrich Hörhold, and Friedrich Kremer. "Unvernetzte Epoxid-Amin-Additionspolymere, 31. Polykationen auf Basis von Epoxid-Amin-Additionspolymeren. Herstellung und Eigenschaften." Die Makromolekulare Chemie 190, no. 12 (December 1989): 3055–60. http://dx.doi.org/10.1002/macp.1989.021901202.

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6

Klee, J., H. H. Hörhold, and H. Schütz. "Hybridnetzwerke – Wege zur Synthese und Nachvernetzung von methacrylatterminierten Epoxid-Amin-Prepolymeren. Unvernetzte Epoxid-Amin-Additionspolymere 30." Acta Polymerica 42, no. 1 (January 1991): 17–20. http://dx.doi.org/10.1002/actp.1991.010420105.

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7

Klee, J., H. J. Flammersheim, and H. Utschick. "Thermomechanische Untersuchungen an Epoxid/Amin-Carbonsäure-Hybridnetzwerken." Acta Polymerica 41, no. 1 (January 1990): 14–17. http://dx.doi.org/10.1002/actp.1990.010410104.

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8

Hollstein, Werner. "Epoxid- und PUR-Systeme erfüllen höchste Ansprüche." adhäsion KLEBEN & DICHTEN 56, no. 12 (December 2012): 26–28. http://dx.doi.org/10.1365/s35145-012-0182-7.

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9

Ickert, Leif, Jan Bochinger, Sebastian de Nardo, and Dinesh Thirunavukkarasu. "Potenziale für semistrukturelle Serienbauteile aus Epoxid-SMC." Lightweight Design 12, no. 1 (March 2019): 40–45. http://dx.doi.org/10.1007/s35725-018-0075-2.

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10

Eckhardt, Matthias, and Reinhard Brückner. "Erste Modellverbindung des Neocarzinostatin-Chromophors mit Epoxid-und Carbonatring." Angewandte Chemie 108, no. 10 (May 20, 1996): 1185–88. http://dx.doi.org/10.1002/ange.19961081016.

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11

Bellstedt, K., H. H. Hörhold, and E. Klemm. "Polymerlegierungen durch Interpenetrations-Polymerisation von Epoxid/Amin-Acrylat Mischungen." Acta Polymerica 38, no. 9 (September 1987): 547–48. http://dx.doi.org/10.1002/actp.1987.010380909.

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12

Klemm, Elisabeth, Hans-Jürgen Flammersheim, Rolf Märtin, and Hans-Heinrich Hörhold. "Versuche zur stufenweisen epoxid/methacrylat-photopolymerisation mit diaryliodoniumsalz-photoinitiatoren." Angewandte Makromolekulare Chemie 135, no. 1 (October 1985): 131–38. http://dx.doi.org/10.1002/apmc.1985.051350111.

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13

Citovický, P., V. Chrástová, P. Rosner, J. Majer, and A. Štaudnerová. "Die Veresterung von an Polypropylen gebundener Polyacrylsäure mit einem Epoxid." Acta Polymerica 36, no. 5 (May 1985): 252–55. http://dx.doi.org/10.1002/actp.1985.010360504.

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14

Vyrozhemskyi, Valerii, Ivan Kopynets, and Oleksii Sokolov. "INCREASING THE PROPERTIES OF ASPHALT CONCRETES BY USING THE EPOXID FORMATION." Avtoshliakhovyk Ukrayiny, no. 2 (258) ’ 2019 (June 27, 2019): 46–50. http://dx.doi.org/10.33868/0365-8392-2019-2-258-46-50.

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One of the main reasons of low durability of asphalt concrete are the properties of bitumen which is the most sensitive of all its components to the action of external factors. As thermoplastic material, bitumen becomes soft at high summer temperatures leading to rutting, shear and sags formation. At low winter time temperatures it becomes fragile and rigid that due to low-temperature compression of asphalt pavement causes the occurrence of transverse cracks. The most effective direction for increasing the durability and roughness of asphalt pavement is changing the bitumen behavior by various types of additives modification. Among the issues related to all known modifiers, the least studied is the issue of using thermosetting polymers, namely, epoxy components. The main problem with the use of epoxy resins for modification is that under the influence of high process temperatures a rapid hardening of the epoxy resin after combining with the hardener occurs. Such behavior of epoxy components limits the temperature modes and the duration of process operations for the production, transportation and placement of epoxy asphalt mixtures. In this paper, the results of the study of epoxy-asphalt concrete obtained using the cut-back bitumen are presented. The dilution of bitumen allows reducing the process temperatures of the production of epoxy asphalt concrete mixtures which increases the time for their transportation and compaction. As a result of hardening of the epoxy resin, over time, a significant increase in the strength of the epoxy asphalt concrete occurs at all temperatures. The rate of hardening of epoxy asphalt depends on the temperature of the environment. As the temperature rises, the reaction rate between the epoxy resin and the hardener increases, which is reflected in the growth of the strength of the epoxy asphalt concrete at all test temperatures, the more intense evaporation of the solvent and, consequently, the growth of water saturation and the decrease in average density. Keywords. epoxy binder, epoxy asphalt concrete, epoxy resin, modification, cut-back bitumen.

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15

Zhang, Yong-Qiang, Nico Funken, Peter Winterscheid, and Andreas Gansäuer. "Hydroxy-dirigierte, Fluorid-katalysierte Epoxid-Hydrosilylierung zur Synthese von 1,4-Diolen." Angewandte Chemie 127, no. 23 (April 20, 2015): 7035–38. http://dx.doi.org/10.1002/ange.201501729.

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16

Henriques, Dina Schwarz G., Katharina Zimmer, Sven Klare, Andreas Meyer, Elena Rojo-Wiechel, Mirko Bauer, Rebecca Sure, et al. "Hochaktive Titanocen-Katalysatoren für Epoxid-Hydrosilylierungen - Synthese, Theorie, Kinetik, EPR-Spektroskopie." Angewandte Chemie 128, no. 27 (April 29, 2016): 7801–5. http://dx.doi.org/10.1002/ange.201601242.

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17

Klee, J., H. H. Hörhold, W. Tänzer, and M. Fedtke. "Hochdruckflüssigkeitschromatographie (HPLC) von DGEBA-Anilin-Prepolymeren. Unvernetzte Epoxid-Amin-Additionspolymere. 10." Acta Polymerica 37, no. 5 (May 1986): 272–78. http://dx.doi.org/10.1002/actp.1986.010370505.

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18

Klee, J., H. H. Hörhold, and J. Raddatz. "Telechele Prepolymere aus DGEBA und disekundären Diaminen. Unvernetzte Epoxid-Amin-Additionspolymere. 29." Acta Polymerica 41, no. 11 (November 1990): 557–60. http://dx.doi.org/10.1002/actp.1990.010411101.

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19

Hörhold, Hans-Heinrich, Joachim Klee, Heidrun Schütz, and Reiner Radeglia. "Unvernetzte epoxid-amin-additionspolymere, 15. 15N-NMR-spektroskopie von DGEBA-anilin-additionspolymeren." Angewandte Makromolekulare Chemie 144, no. 1 (October 1986): 1–9. http://dx.doi.org/10.1002/apmc.1986.051440101.

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20

Elemes, Yiannis, Scott K. Silverman, Chimin Sheu, Michelle Kao, Christopher S. Foote, Marcos M. Alvarez, and Robert L. Whetten. "Reaktion von C60 mit Dimethyldioxiran zu einem Epoxid und einem 1,3-Dioxolan-Derivat." Angewandte Chemie 104, no. 3 (March 1992): 364–66. http://dx.doi.org/10.1002/ange.19921040341.

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21

Klee, J., H. H. Hörhold, and H. Schütz. "Lineare Additionspolymere aus Bisphenol-A-diglycidylether und primären Monoaminen. Unvernetzte Epoxid-Amin-Additionspolymere. 17." Acta Polymerica 38, no. 5 (May 1987): 293–99. http://dx.doi.org/10.1002/actp.1987.010380509.

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22

Lehenmeier, Maximilian W., Stefan Kissling, Peter T. Altenbuchner, Christian Bruckmeier, Peter Deglmann, Anna-Katharina Brym, and Bernhard Rieger. "Zweikernige Zinkkomplexe mit flexibler Verbindung: die Lösung des Entropieproblems der katalytischen CO2/Epoxid-Copolymerisation?" Angewandte Chemie 125, no. 37 (July 19, 2013): 10004–9. http://dx.doi.org/10.1002/ange.201302157.

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23

Chen, Ke, and Rui Wang. "The Mechanical and Aging Properties of the Natural Rubber/Polyvinyl Alcohol (NR/PVA) Blends." Advanced Materials Research 1073-1076 (December 2014): 12–15. http://dx.doi.org/10.4028/www.scientific.net/amr.1073-1076.12.

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The natural rubber/polyvinyl alcohol (NR/PVA) blends containing epoxid natural rubber as the compatilizer were prepared using latex compounding techniques. The mechanical and thermal oxidation aging properties were studied. Mechanical test showed that the tear strength and hardness of the NR were significantly improved due to adding of the PVA. The tensile strength decreased significantly along with the PVA increasing. Thermal oxidation aging test had obviously impact on the mechanical properties of the material. The performance retention of the material properties was taken effect significantly on the aging test.

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24

Song, Lingxia, Yeyun Meng, Peng Lv, Weiqu Liu, and Hao Pang. "Preparation of a Dmap-Catalysis Lignin Epoxide and the Study of Its High Mechanical-Strength Epoxy Resins with High-Biomass Content." Polymers 13, no. 5 (February 28, 2021): 750. http://dx.doi.org/10.3390/polym13050750.

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The depletion of limited petroleum resources used for the fabrication of epoxy resins calls for the development of biomass-based epoxides as promising alternatives to petroleum-derived epoxides. However, it is challenging to obtain an epoxy resin with both high lignin content and excellent mechanical performance. Herein, a 4-dimethylaminopyridine (DMAP)-lignin epoxide with a certain epoxy value and a small molecular weight is obtained by the catalysis of DMAP for the macromolecular lignin. It was discovered that compared to the prepared composite resin of benzyltriethylammonium chloride (BTEAC)-lignin epoxide, there is a better low-temperature storage modulus for the DMAP-lignin epoxide resin and its composite resins with high-biomass contents, and higher tensile strength for its composite resins. In particular, the DMAP-lignin epoxide/ bisphenol A diglycidyl ether (BADGE) (DB) composite resin with DMAP-lignin epoxide replacement of 80 wt% BADGE, containing up to 58.0 wt% the lignin epoxide, exhibits the tensile strength of 76.3 ± 3.2 MPa. Its tensile strength is 110.2% of BTEAC-lignin epoxide/BADGE (BB) composite resins and is comparable to that of petroleum-based epoxy resins. There are good application prospects for the DB composite resin in the engineering plastics, functional composite, grouting, and other fields.

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25

Stolle, Th, H. Pietsch, and I. Ebert. "Ein Beitrag zur Aufklärung irreversibler Desaktivierungsreaktionen in organischen Photoleitern vom Typ der Epoxid-Arylamin-Additionspolymere." Acta Polymerica 38, no. 6 (June 1987): 340–47. http://dx.doi.org/10.1002/actp.1987.010380608.

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26

Klee, Joachim, Hans-Heinrich Hörhold, Heidrun Schütz, Sabi Varbanov, and Gueorgui Borissov. "Unvernetzte Epoxid-Amin-Additionspolymere, 21. Dimethyl(aminomethyl)phosphinoxid, ein comonomeres für epoxidpolymere mit verminderter entflammbarkeit." Angewandte Makromolekulare Chemie 170, no. 1 (June 1989): 145–57. http://dx.doi.org/10.1002/apmc.1989.051700111.

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27

Opfermann, J., H. H. Hörhold, J. Klee, and R. Wondraczek. "Zur Gelchromatographie von Additionspolymeren aus Bisphenol-A-diglycidylether und Anilin. Unvernetzte Epoxid-Amin-Additionspolymere. 8." Acta Polymerica 36, no. 10 (October 1985): 561–65. http://dx.doi.org/10.1002/actp.1985.010361010.

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28

Larin, Evgeni A., Valeri S. Kochubei, and Yuri M. Atroshchenko. "Regio- and stereoselective synthesis of new diaminocyclopentanols." Beilstein Journal of Organic Chemistry 10 (October 28, 2014): 2513–20. http://dx.doi.org/10.3762/bjoc.10.262.

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The optimal conditions for regio- and stereoselective epoxide ring opening of N,N-disubstituted 1,2-epoxy-3-aminocyclopentanes by different nucleophilic reagents have been developed. The substituents on the nitrogen atom in the epoxide precursor and the orientation of the oxirane ring are crucial for the reaction outcome. Thus, treatment of (1RS,2SR,3SR)-1,2-epoxy-3-(N,N-dibenzylamino)cyclopentane (3b) with amines gave a mixture of C1 and C2 regioadducts, while the use of (1RS,2SR,3SR)-1,2-epoxy-3-(N-benzyl-N-methylamino)cyclopentane (3a) led ultimately to C1 adducts. Base-catalyzed aminolysis of epoxides 6a,b afforded mainly C1 adducts 13a,b arising from trans-diaxal opening of the epoxide ring. Using a Lewis acid catalyst, epoxides 6a,b were transformed into diaminocyclopentanols 14a,b via an alternative pathway involving the formation of aziridinium intermediate 17.

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29

Proksa, Bohumil, Bohumil Steiner, Stanislava Uhrínová, and Miroslav Koóš. "Reaction of Dimethylaminoethyl Derivatives of 1-Benzylidenisoindolin-3-one with Epoxides." Collection of Czechoslovak Chemical Communications 57, no. 7 (1992): 1516–20. http://dx.doi.org/10.1135/cccc19921516.

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Derivatives of 1-(2-(2-dimethylaminoethyl)benzyliden)isoindolin-3-one underwent deamination on reaction with epoxides under mild conditions. Amide group of the substrate reacted slower with epoxide than the dimethylamino grouping whilst the alkanolamide was formed with a great excess of the epoxide only. Of epoxides used in this reaction 1,2-epoxy-3-phenoxypropane, 3-decyloxypropane and 3-chloro-1,2-epoxypropane, the first was found to react most rapidly.

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30

Kammerhofer, Philipp. "Untersuchungen zur Haltbarkeit von Formen aus carbonfaserverstärkten Kunststoffen (CFK): Ein Vergleich der Matrixsysteme Epoxid und BMI." Zeitschrift Kunststofftechnik 1 (2018): 118–45. http://dx.doi.org/10.3139/o999.01012018.

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31

Hörhold, H. H., and R. E. Grützner. "Cyclodimer aus Bisphenol-A-diglycidylether und N,N′-disubstituiertem 4,4′-Diaminodiphenylmethan. Unvernetzte Epoxid-Amin-Additionspolymere, 20." Acta Polymerica 38, no. 4 (April 1987): 247–49. http://dx.doi.org/10.1002/actp.1987.010380410.

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32

Jamieson, Megan, Nicola Brant, Margaret Brimble, and Daniel Furkert. "Remarkable Influence of Cobalt Catalysis on Epoxide Ring-Opening with Sulfoxonium Ylides." Synthesis 49, no. 17 (May 8, 2017): 3952–56. http://dx.doi.org/10.1055/s-0036-1588814.

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Cobalt demonstrates a remarkable ability to catalytically divert the course of epoxide to oxetane ring expansion via reaction with a sulfoxonium ylide. An expanded survey of transition-metal catalysts has confirmed that cobalt salts uniquely instead deliver homoallylic alcohol products from epoxides, with retention of the original epoxide stereochemistry. The reaction is an unusual example of cobalt-catalysed epoxide ring-opening by a carbon nucleophile. A tandem Corey–Chaykovsky/epoxide olefination sequence giving homoallylic alcohols from aldehydes is further demonstrated along with preliminary mechanistic analysis. This communication summarises current understanding and ongoing studies into this intriguing new cobalt-mediated reactivity.

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33

Klee, Joachim, Hans-Heinrich Hörhold, Wolfram Tänzer, and Manfred Fedtke. "Unvernetzte epoxid-amin-additionspolymere, 16. HPLC-analyse und 13C-NMR-spektroskopie von telechelen (diglycidylether-bisphenol A)-anilin-prepolymeren." Angewandte Makromolekulare Chemie 147, no. 1 (January 1987): 71–81. http://dx.doi.org/10.1002/apmc.1987.051470107.

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34

Uebelhart, Peter, and Conrad Hans Eugster. "Synthesen von enantiomerenreinen Apoviolaxanthin-s�uren, -olen und -alen (Persicaxanthin, Sinensiaxanthin und ?-Citraurin-epoxid) und ihrer furanoiden Umlagerungsprodukte." Helvetica Chimica Acta 71, no. 8 (December 14, 1988): 1983–98. http://dx.doi.org/10.1002/hlca.19880710817.

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35

Tsikas, Dimitrios, Kay Kohlhaw, and Gorig Brunner. "Funktionen und Anwendung von Glutathion S-Transferase und Epoxid-Hydratase in einem enzymatischen Hohlfaser-Reaktor zur extrakorporalen Entgiftung." Chemie Ingenieur Technik 63, no. 11 (November 1991): 1150–51. http://dx.doi.org/10.1002/cite.330631126.

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36

Velgová, Helena, and Jaroslav Zajíček. "Reaction of 3,4a-disubstituted 4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestane derivatives with reducing agents." Collection of Czechoslovak Chemical Communications 50, no. 11 (1985): 2457–70. http://dx.doi.org/10.1135/cccc19852457.

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Reaction of all stereoisomeric 3-acetoxy-4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestan-4a-ols I-IV with lithium aluminium hydride and reduction of 3-acetoxy-4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestan-4a-ones XXII and XXIII with sodium borohydride were studied. It was found that reductive opening of the 5β,6β-epoxide ring occured only in the case of the derivatives III and IV due to 5(O)n participation of the 3α-oxygen-containing substituent under formation of the transannular 3α,5α-epoxides VIII and IX, resp. On reduction of the 4a-keto epoxides XXII and XXIII with sodium borohydride the trans-epoxy alcohols III and I were formed. On the basis of 1H NMR data the conformation of the A-ring in the epoxides I-IV, XXII, and XXIII is also discussed.

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37

Crowley, Hiidegard H. "Increased Preservation of infrastructure With LR Gold for Immunocytochemistry." Microscopy Today 7, no. 1 (January 1999): 21. http://dx.doi.org/10.1017/s1551929500063781.

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The acrylic embedding media such as LR White, LR Gold, and others, have long been favored over epoxide embedding media for immunocytochemistry in cases where the antigen is sparse or vulnerable to the chemical activity of epoxy monomers. Since acrylics bond through tissue and not with it as epoxides do (1), Au labeling may increase sharply when acrylics are substituted for epoxides. Unfortunately one serious disadvantage of acrylics is their reduced ability to preserve ultrastructure.

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38

Donnelly, Joseph R., G. Wayne Sovocool, and Richard L. Titus. "Structures and Environmental Significance of Heptachlor Epoxide Isomers." Journal of AOAC INTERNATIONAL 76, no. 5 (September 1, 1993): 1092–97. http://dx.doi.org/10.1093/jaoac/76.5.1092.

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Abstract Historically, both endo- and exo-epoxides of heptachlor are known. The exo-epoxy isomer of heptachlor epoxide is a remarkably stable metabolite of heptachlor and is generally found in the environment where heptachlor was introduced. In this study, the nuclear magnetic resonance and mass spectral characteristics of the 2 epoxide-containing isomers ("A" and "B") were investigated to verify their structural assignments. We believe that the metabolite, Isomer B, is the only isomer found in the environment resulting from environmental contamination by chlordane and heptachlor.

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39

Grant, PK, LR Hanton, and SF Tsai. "Intramolecular Rearrangements of Labda-8(17),14-dien-13-ol (Manool) Derivatives." Australian Journal of Chemistry 38, no. 10 (1985): 1461. http://dx.doi.org/10.1071/ch9851461.

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The products of epoxidation of the enol ether 8,13-epoxy-17-norlabd-8-ene (2) arise from the acid-labile acetal nature of the expected epoxide. Acid-promoted 1,2-nucleophilic rearrangements of subsequently formed epoxides give rise to the isolated products, including the novel spiro hydroxy ketone 8β,13-epoxy-7β-hydroxy-10(9→8)abeo-17-norlabdan-9-one (8), the structure of which was determined by X-ray analysis of the acetate derivative. The structure of the major product, 8,13- epoxy-17-norlabd-8-en-7-one (5), was confirmed by synthesis.

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40

Wijekoon, C. P., P. H. Goodwin, and T. Hsiang. "The involvement of two epoxide hydrolase genes, NbEH1.1 and NbEH1.2, of Nicotiana benthamiana in the interaction with Colletotrichum destructivum, Colletotrichum orbiculare or Pseudomonas syringae pv. tabaci." Functional Plant Biology 35, no. 11 (2008): 1112. http://dx.doi.org/10.1071/fp08160.

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Epoxide hydrolase hydrates epoxides to vicinal diols in the phyto-oxylipin peroxygenase pathway resulting in the production of epoxy alcohols, dihydrodiols, triols and epoxides, including many lipid epoxides associated with resistance. Two epoxide hydrolase genes from Nicotiana benthamiana L., NbEH1.1 and NbEH1.2, were amplified from coding DNA of leaves during a susceptible response to the hemibiotrophic pathogens, Colletotrichum destructivum O’Gara, Colletotrichum orbiculare Berk. and Mont. von Arx. or Pseudomonas syringae pv. tabaci Wolf and Foster, or the hypersensitive resistance response to P. syringae pv. tabaci expressing avrPto. Increases in expression of NbEH1.1 generally occurred during the late biotrophic and necrotrophic stages in the susceptible responses and before the hypersensitive response. NbEH1.2 expression was not significantly induced by C. orbiculare but was induced by C. destructivum, P. syringae pv. tabaci and P. syringae pv. tabaci expressing avrPto, although to a lesser degree than NbEH1.1. Virus-induced gene silencing of NbEH1.1 delayed the appearance of lesions for C. destructivum, reduced populations of P. syringae pv. tabaci and increased populations of P. syringae pv. tabaci expressing avrPto. The importance of epoxide hydrolase during pathogen attack may be related to its roles in detoxification, signalling, or metabolism of antimicrobial compounds.

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41

Nagae, Haruki, Ryota Aoki, Shin-nosuke Akutagawa, Julian Kleemann, Risa Tagawa, Tobias Schindler, Gyeongshin Choi, et al. "Lanthanoidkomplexe mit Trizink-Kronenether als Katalysatoren für die alternierende Copolymerisation von Epoxid und CO2 : eine durch Carboxylat-Anionen kontrollierte Telomerisierung." Angewandte Chemie 130, no. 9 (January 17, 2018): 2518–22. http://dx.doi.org/10.1002/ange.201709218.

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42

Höring, Barbara, Erich Blohberger, and Helmut Schürmann. "Experimentelle Untersuchungen zur Dämpfung in Faser-Kunststoff-Verbunden und Beitrag zur Berechnung der Dämpfung von Antriebswellen/Experimental Research on the Damping in Fibre-Polymer-Composites and Remarks how to Analyze the Damping in Drive Shafts." Konstruktion 70, no. 01-02 (2018): 83–90. http://dx.doi.org/10.37544/0720-5953-2018-01-02-83.

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Inhalt: Am Fachgebiet Konstruktiver Leichtbau und Bauweisen der Technischen Universität Darmstadt wurde das Dämpfungsverhalten von Laminaten anhand von Rohr- probekörpern aus Glasfaser-Epoxid-Verbunden untersucht. Der Fokus lag auf der Versuchsdurchführung, insbesondere auf der Kalibrierung der Messtechnik. Im zweiten Schritt stand eine Parametervariation im Vordergrund – konkret der Größen Frequenz, Faserwinkel, Belastungsamplitude und -historie. Die Untersuchungen bestätigen, dass die Dämpfung der untersuchten Laminate im Frequenzbereich von f = 1 Hz bis f = 30 Hz keine Frequenzabhängigkeit aufweist. Hingegen sind die Belastungsamplitude und -historie von großem Einfluss. Es galt daher, die amplituden-abhängigen Dämpfungskennwerte der UD-Schicht zu ermitteln. Zudem zeigte sich, dass eine höhere Dämpfung mit Mikroschädigungen und damit sinkenden Werkstoffsteifigkeiten einhergeht. Die Messergebnisse bildeten die Grundlage für die Dämpfungsberechnung von Laminaten mittels Energiemethode. Die Berechnungsergebnisse für den amplitudenabhängigen Dämpfungsbereich wurden anhand von Versuchen an Rohrprobekörpern validiert. Die Energiemethode liefert konservative Vorhersagen, die sich durch Berücksichtigung der Querzug-Schub-Interaktion in der UD-Schicht auf die Mikrorissbildung noch zuschärfen lassen.

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43

Oldenburg, Johannes, Simone Rost, Andreas Fregin, Christof Geisen, Vytautas Ivaskevicius, Erhard Seifried, Inge Scharrer, et al. "Mutations in the VKORC1 Gene Cause Warfarin Resistance, Warfarin Sensitivity and Combined Deficiency of Vitamin K Dependent Coagulation Factors." Blood 104, no. 11 (November 16, 2004): 277. http://dx.doi.org/10.1182/blood.v104.11.277.277.

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Abstract Coumarins target blood coagulation via inhibition of the vitamin K epoxide reductase multiprotein complex (VKOR). This complex recycles vitamin K 2,3-epoxide to vitamin K hydroquinone, an essential cofactor for the post-translational gamma-carboxylation of several blood coagulation factors. Recently, two groups including ours identified a key component of the VKOR which we named Vitamin K Epoxid Reductase Subunit 1 (VKORC1). The corresponding gene comprises a 5 kb genomic region and consist of three exons encoding a small 163 aa transmembrane protein. Since VKOR was hypothesized to be involved in two heritable diseases, combined deficiency of vitamin K dependent clotting factors type 2 (VKCFD2) and resistance to coumarin-type drugs (warfarin/phenprocoumon resistance, WR) we sequenced the VKORC1 gene in patients with these phenotypes. The same homozygous missense mutation (R98W) was found in two families from Germany and Lebanon with a mild VKCFD2 phenotype. In 7 patients from 5 families with various degrees of WR (weekly warfarin dose ranged from 115 mg to 280 mg, two patients exhibited complete WR) different heterozygous missense mutations distributed throughout the gene (V29L, V45A, R58G, V66M, L128R) were identified. Furthermore, we proved a heterozygous nonsense mutation (W5Stop) in a young female patient with highly increased phenprocoumon sensitivity. Over-expression of the wild-type protein in HEK 293 cells leads to a striking increase in VKOR activity which is sensitive to warfarin inhibition. In contrast to the wild-type protein, the VKCFD2 variant exhibited a dramatically decrease of VKOR activity. The WR variants showed a varying reduction of the VKOR activity, but unexpectedly, were sensitive to warfarin in the HEK cell expression system The reason for the differing WR phenotypes in human and in the HEK cell expression system are still to be elucidated. In conclusion, VKORC1 protein most likely represents the molecular target of coumarins, which have prescribed for oral anticoagulant therapy since more than 60 years. Mutations in the VKORC1 gene are causative for the hereditary conditions of VKCFD2, warfarin resistance and also warfarin sensitivity. Our findings may provide a basis for a rational design of novel anticoagulants targeting VKOR in the future.

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44

Khan, B. "Micro and Macroscopic Features of Impact Failed Defect Induced Carbon-Epoxy Composites / Mikro- und makroskopische Merkmale von aufprallgeschädigten Kohlenstoff-Epoxid-Verbunden." Practical Metallography 36, no. 9 (September 1, 1998): 487–94. http://dx.doi.org/10.1515/pm-1998-360903.

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45

Jalil, Mohd Jumain, Aliff Farhan Mohd Yamin, Mohd Saufi Md Zaini, Veronique Gloria V. Siduru, Norhashimah Morad, Abdul Hadi, and Mohd Jalil. "Kinetics Studies of Epoxidation and Oxirane Cleavage-Epoxidized Palm Kernel Oil." Recent Innovations in Chemical Engineering (Formerly Recent Patents on Chemical Engineering) 13, no. 3 (June 21, 2020): 232–40. http://dx.doi.org/10.2174/2405520413666200117091235.

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Background: Studies pertaining to the epoxidation of fatty acids, garnered much interest in recent years due to the rising demand of eco-friendly epoxides derived from vegetable oils. Methods: Epoxide is an important chemical precursor for the production of alcohols, glycols and polymers, like polyesters and epoxy resin. Epoxidation is the name given to the reaction when the double bonds are converted into epoxide. Results: Temperature at 55oC was used as a reference material in the epoxide process, as it produces a high yield epoxide being 88%. The kinetic rate of epoxidized palm kernel oil, k was obtained to be k11= 0.5125, k12= 0.05045, k21= 0.03185, k41= 0.01 and k51= 0.01243. Conclusion: Hence, by fitting the result with the experimental work and simulation, the summation of error being stimulated by I-sight simulation was 0.731116428 and the correlation between the experimental and simulation data was 0.925544.

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46

Velgová, Helena. "Participation of the oxygen-containing substituent in alkaline saponification of 3,4a-disubstituted 4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestane derivatives." Collection of Czechoslovak Chemical Communications 51, no. 4 (1986): 930–36. http://dx.doi.org/10.1135/cccc19860930.

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Alkaline saponification of the 3-acetoxy group in 3,4a-disubstituted 4,4-dimethyl-5,6β-epoxy-A-homo-5βcholestane derivatives I-VI was studied. It was found that the 3α- and 4aα-hydroxy groups participated in the cleavage of the 5β,6β-epoxide ring in the derivatives II-IV: the 5(O)n participation by the 3α-hydroxy group (the derivatives III and IV) led to formation of the transannular 3α,5α-epoxides XII and XIV whereas the participation by the 4aα-hydroxy group (the derivatives II and IV) gave rise to the 4aα,5α-epoxides IX and XV. The 5(O)n participation by the 3α-hydroxy group predominated over the preparation by the 4aα-hydroxy group. In the case of the 4a-keto epoxides V and VI the retroaldol-aldol type isomerization led to formation of 3β-hydroxy-4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestan-4a-one as the main component of the equilibration mixtures.

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47

van Hylckama Vlieg, Johan E. T., Jaap Kingma, Arjan J. van den Wijngaard, and Dick B. Janssen. "A Glutathione S-Transferase with Activity towards cis-1,2-Dichloroepoxyethane Is Involved in Isoprene Utilization by Rhodococcus sp. Strain AD45." Applied and Environmental Microbiology 64, no. 8 (August 1, 1998): 2800–2805. http://dx.doi.org/10.1128/aem.64.8.2800-2805.1998.

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ABSTRACT Rhodococcus sp. strain AD45 was isolated from an enrichment culture on isoprene (2-methyl-1,3-butadiene). Isoprene-grown cells of strain AD45 oxidized isoprene to 3,4-epoxy-3-methyl-1-butene,cis-1,2-dichloroethene tocis-1,2-dichloroepoxyethane, andtrans-1,2-dichloroethene totrans-1,2-dichloroepoxyethane. Isoprene-grown cells also degraded cis-1,2-dichloroepoxyethane andtrans-1,2-dichloroepoxyethane. All organic chlorine was liberated as chloride during degradation ofcis-1,2-dichloroepoxyethane. A glutathione (GSH)-dependent activity towards 3,4-epoxy-3-methyl-1-butene, epoxypropane,cis-1,2-dichloroepoxyethane, andtrans-1,2-dichloroepoxyethane was detected in cell extracts of cultures grown on isoprene and 3,4-epoxy-3-methyl-1-butene. The epoxide-degrading activity of strain AD45 was irreversibly lost upon incubation of cells with 1,2-epoxyhexane. A conjugate of GSH and 1,2-epoxyhexane was detected in cell extracts of cells exposed to 1,2-epoxyhexane, indicating that GSH is the physiological cofactor of the epoxide-transforming activity. The results indicate that a GSHS-transferase is involved in the metabolism of isoprene and that the enzyme can detoxify reactive epoxides produced by monooxygenation of chlorinated ethenes.

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48

Seidel, H., B. Pötzsch, M. Watzka, and J. Oldenburg. "Neue Einsichten in die orale Antikoagulationstherapie mit Cumarinen." Hämostaseologie 28, no. 01/02 (March 2008): 44–50. http://dx.doi.org/10.1055/s-0037-1616921.

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ZusammenfassungDie Identifizierung der Vitamin-K-Epoxid-Reduktase (VKORC1) hat maßgeblich zu einem besseren Verständnis des Vitamin-K-Zyklus beigetragen. Das VKORC1-Protein konnte als das molekulare Target der Cumarine charakterisiert werden und stellt das geschwindigkeitsbestimmende Enzym des Vitamin-K-Zyklus und möglicherweise die alleinige Komponente der VKOR-Aktivität dar. Mutationen und Polymorphismen innerhalb der translatierten und nicht translatierten Regionen des VKORC1-Gens verursachen partielle bis totale Cumarin-Resistenz und -Sensitivität. Die Verfügbarkeit einer molekulargenetischen Diagnostik (VKORC1, CYP2C9) und einer Laboranalytik mittels HPLC (zur Bestimmung des Cumarin-, Vitamin-K- und Vitamin- K-Epoxidspiegels) ist hilfreich in der Detektion hereditärer und erworbener Einflussgrößen der Cumarintherapie und könnte zukünftig für eine individualisierte, risikoärmere orale Antikoagulationstherapie zum Einsatz kommen.Eine niedrig dosierte tägliche Vitamin-K-Supplementierung scheint geeignet, die Sicherheit einer oralen Antikoagulationstherapie mit Cumarinen zu verbessern. Bei der Entwicklung neuer und auf molekularer Ebene selektiv wirkender oraler Antikoagulanzien wird sich somit die Frage nach gleich guter Effektivität und Sicherheit im Vergleich zu den ˶alten“ Antikoagulanzien stellen. Gerade auch unter dem Aspekt der Ökonomie könnten die bewährten Cumarine durch eine pharmakogenetisch und nutritiv adaptierte Therapieoptimierung eine Renaissance erfahren.

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49

Yamanashi, Haruto, William E. Boeglin, Christophe Morisseau, Robert W. Davis, Gary A. Sulikowski, Bruce D. Hammock, and Alan R. Brash. "Catalytic activities of mammalian epoxide hydrolases with cis and trans fatty acid epoxides relevant to skin barrier function." Journal of Lipid Research 59, no. 4 (February 19, 2018): 684–95. http://dx.doi.org/10.1194/jlr.m082701.

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Lipoxygenase (LOX)-catalyzed oxidation of the essential fatty acid, linoleate, represents a vital step in construction of the mammalian epidermal permeability barrier. Analysis of epidermal lipids indicates that linoleate is converted to a trihydroxy derivative by hydrolysis of an epoxy-hydroxy precursor. We evaluated different epoxide hydrolase (EH) enzymes in the hydrolysis of skin-relevant fatty acid epoxides and compared the products to those of acid-catalyzed hydrolysis. In the absence of enzyme, exposure to pH 5 or pH 6 at 37°C for 30 min hydrolyzed fatty acid allylic epoxyalcohols to four trihydroxy products. By contrast, human soluble EH [sEH (EPHX2)] and human or murine epoxide hydrolase-3 [EH3 (EPHX3)] hydrolyzed cis or trans allylic epoxides to single diastereomers, identical to the major isomers detected in epidermis. Microsomal EH [mEH (EPHX1)] was inactive with these substrates. At low substrate concentrations (<10 μM), EPHX2 hydrolyzed 14,15-epoxyeicosatrienoic acid (EET) at twice the rate of the epidermal epoxyalcohol, 9R,10R-trans-epoxy-11E-13R-hydroxy-octadecenoic acid, whereas human or murine EPHX3 hydrolyzed the allylic epoxyalcohol at 31-fold and 39-fold higher rates, respectively. These data implicate the activities of EPHX2 and EPHX3 in production of the linoleate triols detected as end products of the 12R-LOX pathway in the epidermis and implicate their functioning in formation of the mammalian water permeability barrier.

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50

van Loo, Bert, Jaap Kingma, Michael Arand, Marcel G. Wubbolts, and Dick B. Janssen. "Diversity and Biocatalytic Potential of Epoxide Hydrolases Identified by Genome Analysis." Applied and Environmental Microbiology 72, no. 4 (April 2006): 2905–17. http://dx.doi.org/10.1128/aem.72.4.2905-2917.2006.

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ABSTRACT Epoxide hydrolases play an important role in the biodegradation of organic compounds and are potentially useful in enantioselective biocatalysis. An analysis of various genomic databases revealed that about 20% of sequenced organisms contain one or more putative epoxide hydrolase genes. They were found in all domains of life, and many fungi and actinobacteria contain several putative epoxide hydrolase-encoding genes. Multiple sequence alignments of epoxide hydrolases with other known and putative α/β-hydrolase fold enzymes that possess a nucleophilic aspartate revealed that these enzymes can be classified into eight phylogenetic groups that all contain putative epoxide hydrolases. To determine their catalytic activities, 10 putative bacterial epoxide hydrolase genes and 2 known bacterial epoxide hydrolase genes were cloned and overexpressed in Escherichia coli. The production of active enzyme was strongly improved by fusion to the maltose binding protein (MalE), which prevented inclusion body formation and facilitated protein purification. Eight of the 12 fusion proteins were active toward one or more of the 21 epoxides that were tested, and they converted both terminal and nonterminal epoxides. Four of the new epoxide hydrolases showed an uncommon enantiopreference for meso-epoxides and/or terminal aromatic epoxides, which made them suitable for the production of enantiopure (S,S)-diols and (R)-epoxides. The results show that the expression of epoxide hydrolase genes that are detected by analyses of genomic databases is a useful strategy for obtaining new biocatalysts.

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