16,843 research outputs found
An Article About Albertus C. Van Raalte, Author Unknown, Except for Parts Taken from an Article by Anna C. Post
Get PDFAn article about Albertus C. Van Raalte, author unknown, except for parts taken from an article by Anna C. Post. The author knew first generation persons in the Holland settlement and therefore, the article has some value.https://digitalcommons.hope.edu/vrp_1890s/1012/thumbnail.jp
Kemiallinen ja entsymaattinen happihapetus teknisen ligniinin valorisoinnissa materiaalisovelluksia varten
No full textOxidation by molecular oxygen (O2) is one of the lignin modification methods. O2 is active towards phenolic groups, which are particularly abundant in kraft and soda lignins. The main aim of this thesis was to apply oxidation by O2 to modify technical lignins to enhance their utilization for polymeric chemicals and material applications. O2 oxidation was aided by using either alkaline conditions or laccase enzyme as a catalyst. In addition, oxygen delignification of pulp was studied using kraft lignin as a model substrate to provide data for a mechanistic model for the process. Lignin oxidation mechanisms by O2 under alkaline conditions and laccase catalysis are discussed.
A simple alkali-O2 oxidation method under high lignin content was developed to increase the water solubility of soda lignin, desirable for dispersing applications. Lignin characterization was done directly from the reaction solution. Both the negative charge and the molecular mass of the lignin were controlled by the oxidation parameters, and especially by pH. Oxidation without controlling the pH decrease caused condensation and an increase in molecular mass. Oxidation under a constant pH of 11.5 clearly hindered the condensation and increased the negative charge. Oxidation at constant pH of 13 decreased molecular mass. The results indicate that the organic hydroperoxide formed via coupling of a phenoxyl radical with superoxide (O2•-) is the key intermediate. The course of further reactions is dependent on the degree of protonation of this intermediate (pKa 12–13) and is thus pH dependent. The hydroperoxide anion rearranges leading to degradation. Below pH 12, the protonated form decomposes back to the phenoxyl radical, which spontaneously undergoes coupling and thus induces condensation. Under laccase catalysis conditions, O2•- is not present and thus the reaction paths described above do not function. Therefore, the formed phenoxyl radicals couple with each other rather than degrade. O2 has a significantly lower tendency to attach to the phenoxyl radical compared to O2•-.
The oxidized soda lignin solutions were applied as ready-to-use products for concrete plasticizing. They were superior to commercial lignosulfonate and good in comparison to synthetic superplasticizers. The best performing lignin solution (oxidized at a constant pH of 11.5) also showed promising results in other concrete application tests.
To enhance the utilization of kraft lignin in composite applications, both laccase- and alkali-catalyzed O2 oxidation were used to polymerize lignin-derived low-molecular phenolics for the reduction of VOCs. According to sensing and chemical analysis, the undesirable odor and the formation of VOCs under elevated temperatures were reduced to a greater extent by alkali- than by laccase-catalyzed oxidation. However, neither method led to adequate odor removal. In order to lower the glass transition temperature of lignin, functionalization with a hydrophilic phenolic compound was attempted. However, homogeneous polymerization of this compound was favored over coupling to lignin.
The operating conditions of alkali-O2 oxidation could probably be optimized for targeted lignin characteristics, which would increase the further application potential of technical lignins. Laccase-catalyzed oxidation is best applied when lignin polymerization is desired.Hapetus molekyylisellä hapella (O2) on yksi ligniinin muokkausmenetelmistä. O2 reagoi fenolisten ryhmien kanssa, joita on runsaasti erityisesti sulfaatti- ja soodaligniineissä. Tässä työssä päätavoitteena oli soveltaa O2-hapetusta teknisten ligniinien muokkaukseen, jotta niiden käyttö polymeerisenä kemikaalina ja materiaalisovelluksissa helpottuisi. O2-hapetus toteutettiin joko alkalisissa olosuhteissa tai entsyymiavusteisesti lakkaasilla. Lisäksi työssä tutkittiin massan happidelignifiointia käyttäen malliaineena sulfaattiligniinia. Näin tuotettiin tietoa kyseisen prosessin mekanismimallinnusta varten. Työssä käsitellään ligniinin O2-hapetusmekanismeja alkalisissa olosuhteissa ja lakkaasikatalysoidusti.
Soodaligniinille kehitettiin yksinkertainen korkeassa ligniinipitoisuudessa tapahtuva alkali-O2 -hapetusmenetelmä, joka nostaa ligniinin vesiliukoisuutta dispergointisovelluksia varten. Ligniiniä luonnehdittiin suoraan reaktioliuoksesta. Sekä ligniinin negatiivista varausta että moolimassaa hallittiin hapetusparametreilla, erityisesti pH:n avulla. Hapetus ilman pH-laskun hallintaa aiheutti kondensaatiota ja kasvatti moolimassaa. Hapetus vakio-pH:ssa 11.5 esti selvästi kondensaatiota ja kasvatti negatiivista varausta. Hapetus vakio-pH:ssa 13 pienensi moolimassaa. Tulokset osoittavat, että orgaaninen hydroperoksidi, joka muodostuu fenoksiradikaalin ja superoksidin (O2•-) yhdistyessä, on oleellinen välituote. Jatkoreaktioiden suunta on riippuvainen välituotteen protonoitumisasteesta (pKa 12–13) ja siten pH:sta. Hydroperoksidianionin uudelleenjärjestäytyminen johtaa pilkkoutumiseen. pH:ssa alle 12 sen protonoitunut muoto hajoaa takaisin fenoksiradikaaliksi, joka yhdistyy spontaanisti toiseen vastaavaan ja siten aikaansaa kondensaatiota. Lakkaasikatalysoiduissa olosuhteissa O2•- ei esiinny, ja siksi yllä esitetyt reaktiopolut eivät toimi. Tämän takia muodostuneet fenoksiradikaalit yhdistyvät keskenään sen sijaan, että hajoaisivat. O2 reagoi fenoksiradikaalin kanssa merkittävästi hitaammin kuin O2•-.
Hapetettuja soodaligniiniliuoksia käytettiin sellaisenaan tuotteena betonin notkistuksessa. Ne toimivat selvästi paremmin kuin kaupallinen lignosulfonaatti ja olivat vertailukelpoisia suhteessa synteettisiin tehonotkistimiin. Parhaiten toiminut ligniiniliuos (hapetettu vakio-pH:ssa 11.5) oli lupaava myös muiden betonisovellustestien mukaan.
Sekä lakkaasi- että alkalikatalysoitua O2-hapetusta käytettiin ligniiniperäisten, pienimolekyylisten fenoleiden polymerointiin sulfaattiligniinissä. Näin pyrittiin vähentämään haihtuvien yhdisteiden määrää ja edistämään ligniinin käyttöä komposiittisovelluksissa. Aistiin perustuvan ja kemiallisen analyysin mukaan alkalikatalysoitu hapetus vähensi hajua ja haihtuvien yhdisteiden muodostumista korkeissa lämpötiloissa enemmän kuin lakkaasikatalysoitu. Kumpikaan menetelmistä ei kuitenkaan johtanut riittävään hajun poistoon. Ligniiniin yritettiin liittää vesiliukoinen fenolinen yhdiste, jotta sen lasinsiirtymälämpötila alenisi. Yhdiste kuitenkin homopolymeroitui sen sijaan, että olisi liittynyt ligniiniin.
Alkali-O2 -hapetuksen toimintaolosuhteita optimoimalla saavutetaan hyvin todennäköisesti haluttuja ligniiniominaisuuksia, mikä edistäisi teknisten ligniinien sovelluspotentiaalia entisestään. Lakkaasikatalysoitu hapetus soveltuu parhaiten ligniinin polymerointiin
Richardson, Barbauld, and the construction of an early modern fan club
No full textMPhilMuch has been written about the life and long works of the eighteenth century epistolary novelist, Samuel Richardson, but the prospect of his position as the first celebrity novelist – responsible for courting his own fame as well as initiating his own fan club – has largely been ignored. The body of manuscripts housed at the National Art Library in the Victoria and Albert Museum in London provides the modern scholar with evidence of the skeletal beginnings of an early fan club. This thesis aims to show how these manuscripts were turned into a saleable commodity by the publisher and entrepreneur Richard Phillips, while under the guiding hand of another, slightly later, literary celebrity, Anna Laetitia Barbauld. In order to restore Richardson’s reputation amongst a new nineteenth century audience, Barbauld was required to construct her own idea of him as an eighteenth century celebrity author, and in doing so the insecurities of a self-professed, apparently diffident man, are revealed. Barbauld’s capacious, but heavily edited selection of letters is analyzed in this thesis, providing ample evidence that Richardson’s correspondents were more than just eager letter writers. By using Barbauld’s biography of Richardson this thesis aims to show how she manipulates the genre of life writing in her construction of him.
This thesis offers an alternative reading of how the Richardson manuscripts are viewed, redefining them as not simply a collection of letters, but as a collective entity, deliberately selected and archived as evidence of an early modern fan club, and its celebrity managing director
Selection of work by Anna Gerber
Get PDFVarious journals and magazines Anna Gerber has contributed to. Anna Gerber is a graphic designer and writer based in London.
She is the author and designer of All Messed Up: Unpredictable Graphics (Laurence King, 2004) and co-editor and co-designer
of Influences: A Lexicon of Contemporary Graphic Design (Die Gestalten Verlag, 2006) with Anja Lutz. She writes regularily for magazines such as Print, Eye, Creative Review, Varoom and Idea Magazine and her work has also been published in shift!, dot dot dot and +rosebud.
She teaches at the London College of Communication on the BA Graphic Design and MA Design Writing Criticism programmes. She has also held workshops and lectures across the U.K. (including Tate Modern and the V&A Museum), as well as in India, the U.S., Australia and Malaysia.
Anna Gerber is currently engaged in research and developing projects relating to sustainability and how it applies to graphic
design as well as exploring contemporary graphic design in India
Author and Lecturer Anna Bird Stewart will Speak at the University of Dayton
Get PDFNews release announcing the visitation and speech of author and lecturer Anna Bird Stewart to the University of Dayton
Operatori del processo edilizio
Get PDFLemma che descrive i diversi attori del processo edilizio, con particolare attenzione al processo edilizio pubblico - ISBN:ISSN 2284-00IX - visibile su: Wikitecnica.com/author/giovenale-anna-mari
Processo edilizio
No full textLemma che descrive e reinterpreta, rispetto alla letteratura scientifica, il concetto di processo edilizio, definendone l'evoluzione nel tempo ISBN:ISSN 2284-00IX - Visibile su: wikitecnica.com/author/giovenale-anna-mari
Metaprogettazione
No full textLemma che descrive il concetto di metaprogettazione e pone in risalto l'importanza nell'architettura contemporanea dello strumento "metaprogetto" - ISBN:ISSN 2284-00IX - visibile su: Wikitecnica.com/author/giovenale-anna-mari
Ep. #002 - Anna Tsing
No full textThis recording and transcript form part of a collection of podcasts conducted by the Cultures of Energy at Rice University. Cultures of Energy brings writers, artists and scholars together to talk, think and feel their way into the Anthropocene. We cover serious issues like climate change, species extinction and energy transition. But we also try to confront seemingly huge and insurmountable problems with insight, creativity and laughter.Cultures of Energy Podcast is now on iTunes! Stitcher soon! We celebrate Anna Tsing, Professor of Anthropology at the University of California Santa Cruz, one of the world’s greatest analysts of globalization and the environment and the author (most recently) of The Mushroom at the End of the World: On the Possibility of Life in Capitalist Ruins. Then (6:16) Cymene and Anna talk about feminist legacies, more-than-human anthropology, capitalist ruins and how to think with weeds and mushrooms
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