Sequential curing of thiol-acetoacetate-acrylate thermosets by latent Michael addition reactions

Thiol-acetoacetate-acrylate ternary dual-curing thermosets were prepared by a sequential process consisting of thiol-Michael addition to acrylates at room temperature followed by Michael addition of acetoacetates to acrylates at moderately elevated temperature. The curing sequence can be controlled with the help of the different acidities of the protons on thiol and acetoacetate groups, the favorable pKa of the base used as catalyst and the self-limiting character of Michael additions. The latency of the curing steps can be regulated by selection of the right catalysts, temperature and curing conditions. The properties of the intermediate and final materials can be tuned by changing the structure of the monomers and the contribution of both Michael addition reactions.Postprint (author's final draft

Acetoacetate based thermosets prepared by dual-Michael addition reactions

A novel set of dual-curable multiacetoacetate-multiacrylate-divinyl sulfone ternary materials with versatile and manipulable properties are presented. In contrast to common dual-curing systems, the first stage polymer herein consists of a densely crosslinked, high Tg network as a result of base-catalyzed multiacetoacetate-divinyl sulfone Michael addition. A more flexible secondary network forms after base-catalyzed Michael addition of remaining multiacetoacetate to multiacrylate. Curing is truly sequential as the rates of the two Michael additions are significantly different. Curing kinetics were analyzed using differential scanning calorimetry (DSC) and Fourier-transform infrared (FTIR). The materials at each curing stage were characterized using dynamic mechanical analysis (DMA) and SEM. Although some phase separation was observed in certain formulations, the incompatibilities were minimized when the molar percentage of the acetoacetate-divinyl sulfone polymer network was above 75%. Furthermore, the environmental scanning electron microscopy (ESEM) images of these materials show that the more flexible acetoacetate-acrylate phase is dispersed in the form of polymeric spheres within the rigid acetoacetate-divinyl sulfone matrix. This unique dual microstructure can potentially render these materials highly resilient in applications requiring densely crosslinked polymer architectures with enhanced toughnesPostprint (published version

Kinetics and mechanism of organocatalytic aza-Michael additions: direct observation of enamine intermediates.

The imidazoles 1a–g add to the CC-double bond of the iminium ion 2 with rate constants as predicted by the equation log k = sN(N + E). Unfavourable proton shifts from the imidazolium unit to the enamine fragment in the adduct 3 account for the failure of imidazoles to take part in iminium-activated aza-Michael additions to enals

Substrate control in stereoselective lanthionine biosynthesis.

Enzymes are typically highly stereoselective catalysts that enforce a reactive conformation on their native substrates. We report here a rare example in which the substrate controls the stereoselectivity of an enzyme-catalysed Michael-type addition during the biosynthesis of lanthipeptides. These natural products contain thioether crosslinks formed by a cysteine attack on dehydrated Ser and Thr residues. We demonstrate that several lanthionine synthetases catalyse highly selective anti-additions in which the substrate (and not the enzyme) determines whether the addition occurs from the re or si face. A single point mutation in the peptide substrate completely inverted the stereochemical outcome of the enzymatic modification. Quantum mechanical calculations reproduced the experimentally observed selectivity and suggest that conformational restraints imposed by the amino-acid sequence on the transition states determine the face selectivity of the Michael-type cyclization

Friends of Musselman Library Newsletter Spring 2019

From the Dean (Robin Wagner) Library News Don\u27t Judge a book by its Cover: The Human Library You Can Come Home Again! Exhibits Recalling WWII at Home (Devin McKinney and Micheal Birkner) Library Works to Alleviate Textbook Misery (Janelle Wertzberger) Books Sent to African Library (Piper O\u27Keefe \u2717) Musselman Makeover Paying it Forward (Sierra Green \u2711 and Olivia Simmet \u2718) Student Paper Tops 1800 Downloads (Dayna Seeger \u2715) Buy the Book What\u27s so Funny (Sunni DeNicola) Book Displays Offer Outreach Opportunities (Sunni DeNicola) Honor With Books Data Drives Collecting Decisions Rare Discovery: Signed 1st Edition by Adam Smith Pressed Within - Discovering Unusual Bookmarks Unusual Book Formats Alumna Funds Novels with Diversity Themes (Sarah Blumig \u2710) I Couldn\u27t Let Them Go (Robin Wagner) Aldus Printing Device (Mary Wootton) $25,000 Book Conservation Gift (Rev. Vic Myers) Focus on Philanthropy: Elizabeth Headley Paul Special Additions (John Kuhs, Jr.) The Artistry of Endpapers (Michael Hobor \u2769

Friends of Musselman Library Newsletter Spring 2019

From the Dean (Robin Wagner) Library News Don\u27t Judge a book by its Cover: The Human Library You Can Come Home Again! Exhibits Recalling WWII at Home (Devin McKinney and Micheal Birkner) Library Works to Alleviate Textbook Misery (Janelle Wertzberger) Books Sent to African Library (Piper O\u27Keefe \u2717) Musselman Makeover Paying it Forward (Sierra Green \u2711 and Olivia Simmet \u2718) Student Paper Tops 1800 Downloads (Dayna Seeger \u2715) Buy the Book What\u27s so Funny (Sunni DeNicola) Book Displays Offer Outreach Opportunities (Sunni DeNicola) Honor With Books Data Drives Collecting Decisions Rare Discovery: Signed 1st Edition by Adam Smith Pressed Within - Discovering Unusual Bookmarks Unusual Book Formats Alumna Funds Novels with Diversity Themes (Sarah Blumig \u2710) I Couldn\u27t Let Them Go (Robin Wagner) Aldus Printing Device (Mary Wootton) $25,000 Book Conservation Gift (Rev. Vic Myers) Focus on Philanthropy: Elizabeth Headley Paul Special Additions (John Kuhs, Jr.) The Artistry of Endpapers (Michael Hobor \u2769

Friends of Musselman Library Newsletter Fall 2019

From the Dean (Robin Wagner) Library News Cite and Bite Workshops Open Access Week (Janelle Wertzberger, Alecea Standlee, Hana Huskic) Notes at Noon Friends Sponsor Guild Participation (Mary Wootton) Stop the Bleed The Wall Must Go Story Time Table to Farm Pop-up Library Take the Reading Challenge 1,000,000 Grant to Digitize Asian Art Vietnam Oral Histories (Ron Bailey \u2767, Sue Hill \u2767, Michael Birkner, Devin McKinney) Alexander von Humboldt\u27s Secretary (William Bowman) Focus on Philanthropy: Walter Miller Trust A Gift in 3 Dimensions (Richard C. Ryder \u2770) Remembering Richard Ryder \u2770 (Michael Birkner) New Externship - Careers in Library and Information Science (Camille Minns \u2720, Jivan Kharel \u2720) Textbook Affordability is a Workshop Topic (Janelle Wertzberger) Candid Camera (Dwight Eisenhower, Willard Paul, William C. Darrah) GettDigital: Rooted in Memory Uncovering Shakespeare\u27s Sisters (Suzanne Flynn) Touchdown: First Year Athletes Trade Field for Library (Betsy Bein, John Dettinger) Recent Additions: World War II - Photographs and Memorabilia (William Millar \u2754, Walter Lane, Gerald Royals \u2752, Donald Gallion \u2748, Ralph Edgar Peters, Burdette J. Marker) Alumnus Donates Trade Cards (Gary Thompson \u2769

Fall 2005

Content: Message from the University Librarian by Johnnie Ann Ralph Michael Burgess Retires by Brent Singleton Database Additions and Updates: Biological Abstracts on Board for Fall by Stacy Magedanz The Book and Beyond, Part II: Remembrance of Things Past Quiet Zone Comes to 5th Floor by Lisa Bartle Library Goings O

Proposal for encoding Myanmar characters for Karen and Kayah in the UCS

This is a proposal to add characters to the international character encoding standard Unicode for minority languages using the Myanmar script. These additions were published in Unicode Standard version 5.1 in March 2008. This proposal includes characters for Western Pwo Karen, Eastern Pwo Karen, Geba Karen, and Kayah. Some changes were made after the proposal was written, so users should consult the latest Unicode code charts for the most up-to-date repertoire, accessible from: