117,403 research outputs found
De Fabbroni a Chaptal: a fermentação do vinho entre o flogístico e a “nova química”
No full textA busca por melhorar a qualidade e aumentar a longevidade dos vinhos na França e em regiões que hoje fazem parte da Itália levou alguns autores a escrever obras sobre a produção dessa bebida entre a segunda metade do século XVIII e o início do XIX. Nesse período, os vinhos comuns raramente duravam mais do que um ano. A fermentação alcoólica é um dos aspectos abordados com destaque nesses livros.
Em 1787, o autor toscano Adamo Fabbroni (1748-1816) publicou em Florença Dell’ arte di fare il vino, livro em que formula uma teoria sobre a fermentação do vinho baseada em ideias flogísticas. Em 1801, o químico francês Jean-Antoine Chaptal (1756-1832) lançou em Paris L’ art de faire le vin, obra que trata da elaboração do vinho sobre a ótica da nova química de Antoine-Laurent Lavoisier (1743-1794).
O objetivo desta tese é comparar as visões de Fabbroni e Chaptal sobre a fermentação do vinho e mostrar pontos em comum e divergências desses dois autores sobre esse processo químico em um momento em que as ideias dominantes nessa disciplina faziam a transição de concepções flogísticas para uma “nova química”The quest to improve the quality and increase the longevity of wines in France and in regions that are now part of Italy led some authors to write works on the production of this beverage between the second half of the 18th century and the beginning of the 19th. In this period, ordinary wines rarely lasted more than a year. Alcoholic fermentation is one of the aspects discussed with prominence in these books.
In 1787 the Tuscan author Adamo Fabbroni (1748-1816) published in Florence Dell' arte di fare il vino, a book in which he formulates a theory on the fermentation of wine based on phlogistic ideas. In 1801, the French chemist Jean-Antoine Chaptal (1756-1832) published in Paris L 'art de faire le vin, a work dealing with winemaking from the perspective of the new chemistry of Antoine-Laurent Lavoisier (1743-1794).
The objective of this thesis is to compare the visions of Fabbroni and Chaptal on wine fermentation and to show common points and divergences of these two authors about this chemical process at a time when the dominant ideas in this discipline made the transition from phlogistic conceptions to a "new chemistry "Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPE
Guanine-rich oligonucleotides targeted to a critical RY site located in the Ki-ras promoter. Effect of competing self-structures on triplex formation.
No full textInhibition of T7 RNA polymerase transcription by phosphate and phosphorothioate triplex-forming oligonucleotides targeted to a R.Y site downstream from the promoter.
No full text(A,G)-Oligonucleotides form extraordinary stable triple helices with a critical RY sequence of the murine c-Ki-ras promoter and inhibit transcription in transfected NIH3T3 cells.
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Sequence-specific DNA-triplex formation at imperfect homopurine-homopyrimidine sequences within a DNA plasmid
No full textHighly Regio- and Diastereoselective Palladium-Catalyzed Allylic Substitution. Synthesis of 3-(2-aminobutylidene)-4-arylazetidin-2-ones
No full textThe palladium-catalyzed benzylamine attack to a particular allylic moiety, the 3-alkenyl-3-bromo-azetidin-2-one is herein reported. This reaction shows interesting mechanistic aspects and allows to introduce in one step and under high regio- and stereocontrol the amino function in the C3 side chain of the non conventional beta-lactams, thus offering the opportunity for designing new potential glutamine syntethase inhibitors, such as Tabtoxin analogues
Zinc metal-promoted nucleophilic addition of azetidin-2-ones to aldehydes and nitriles
No full textThe reactivity of in situ generated organozinc reagents of 3-alkenyl-3-bromoazetidin-2-ones with aromatic and aliphatic aldehydes to give the corresponding alcohol derivatives has been studied. The effect of solvent and Lewis acids has been explored in order to improve the reaction yields. The application of this methodology to nitriles and acyl chlorides allowed the preparation of the corresponding keto derivatives. The products of these reactions could be of interest on account of their structural similarity with the already known cholesterol adsorption inhibitor
Highly diastereoselective allylic azide formation and isomerization. Synthesis of 3(2 '-amino)-beta-lactams
No full textThe stereoselective anti S(N)2' attack of NaN3 to 3-alkenyl-3-bromo-azetidin-2-ones gave a mixture of diastereomeric azides in fast equilibrium. The [3,3]-sigmatropic rearrangement of allylic azides occurred with complete stereocontrol, allowing the equilibrium to be directed preferentially toward the (E)- or (Z)-isomer, useful precursors of 3(2'-amino)-beta-lactams
Reazioni di cicloaddizione tra alfa-bromocheteni insaturi e immine. Applicazioni alla sintesi di potenziali inibitori biologici
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