El comportamiento post-critico de las vigas de acero armadas con chapas delgadas

An advance of expositions concerning the method of ultimate strength or post-critical strength of steel beams reinforced with thin plates is presented. This method is being object of experimental researches at the Applied Mechanics and Structures Institute (IMAE) of the Mathematics and Engineering Faculty, National University, Rosario (Argentina).Se presenta un avance de planteamientos relativos al método de la resistencia última o resistencia post-crítica de vigas de acero armadas con chapas delgadas, el cual está siendo objeto de investigaciones experimentales en el Instituto de Mecánica Aplicada y Estructuras (IMAE) de la Facultad de Ciencias Exactas e Ingeniería de la Universidad Nacional de Rosario (República Argentina)

Application of Hansch’s Model to Capsaicinoids and Capsinoids: A Study Using the Quantitative Structure−Activity Relationship. A Novel Method for the Synthesis of Capsinoids

We describe a synthetic approach for two families of compounds, the capsaicinoids and capsinoids, as part of a study of the quantitative relationship between structure and activity

Fine grain thermal modeling and experimental validation of 3D-ICs

n/

Tuning chelation by the surfactant-like peptide A6H using predetermined pH values

We examine the self-assembly of a peptide A6H comprising a hexa-alanine sequence A6 with a histidine (H) “head group”, which chelates Zn2+ cations. We study the self assembly of A6H and binding of Zn2+ ions in ZnCl2 solutions, under acidic and neutral conditions. A6H self-assembles into nanotapes held together by a β-sheet structure in acidic aqueous solutions. By dissolving A6H in acidic ZnCl2 solutions, the carbonyl oxygen atoms in A6H chelate the Zn2+ ions and allow for β-sheet formation at lower concentrations, consequently reducing the onset concentration for nanotape formation. A6H mixed with water or ZnCl2 solutions under neutral conditions produces short sheets or pseudocrystalline tapes, respectively. The imidazole ring of A6H chelates Zn2+ ions in neutral solutions. The internal structure of nanosheets and pseudocrystalline sheets in neutral solutions is similar to the internal structure of A6H nanotapes in acidic solutions. Our results show that it is possible to induce dramatic changes in the self-assembly and chelation sites of A6H by changing the pH of the solution. However, it is likely that the amphiphilic nature of A6H determines the internal structure of the self-assembled aggregates independent from changes in chelation

Certificazione di progetto. Cos\u2019\ue8, come si ottiene e quali vantaggi riserva al settore

Con l'affermarsi della bioedilizia e, pi\uf9 in generale, dell'edilizia in legno, anche la certificazione forestale ha sviluppato strumenti specifici. Accanto alla certificazione della gestione forestale e della catena di custodia, negli ultimi anni \ue9 andata affermandosi la certificazione di progetto. Tale tipologia di certificazione consente di certificare interi progetti (es. un edificio) o parti degli stessi (es. pavimenti, tetto, serramenti) purch\ue9 vi sia impiego di legno certificato. Nel mondo i progetti certificati sono circa 40, due dei quali in Italia. L'utilizzo di legno certificato \ue9 inoltre oggetto di interesse anche da parte di altri standard di certificazione settoriali, quali LEED e BREEAM. La certificazione di progetto potrebbe consentire di coniugare due pratiche virtuose: (i) l\u2019uso del legno in edilizia, con vantaggi in termini ambientali, energetici, tecnologici, di benessere umano ed estetici, e (ii) la gestione responsabile delle foreste. Essa consente infatti di dare garanzia dell\u2019approvvigionamento e dell\u2019impiego di legno proveniente da aree forestali gestite nel rispetto di criteri ambientali, sociali ed economici, dimostrandone la veridicit\ue0 e dandone visibilit\ue0

Constituents of Nothapodytes foetida

Five new alkaloids, along with camptothecin 1 and 9-methoxycamptothecin 2, were isolated from a trunk bark extract of Nothapodytes foetida (Wight) Sleumer (lcacinaceae). The structures were elucidated by spectroscopic means as mappicine and the 9-methoxymappicine glycosides (3-6) and the di-p-coumaroylspermidine ester of a camptothecin-like compound 7, which we have named foetidin I

Cerium(III) chloride-promoted chemoselective esterification of phenolic alcohols

A mild and operationally simple method for the chemoselective esterification of phenolic alcohols is described. The reaction overcomes the tyranny of protection, and capitalizes on the activation of acyl halides with cerium(III) chloride to selectively esterify alcohol hydroxyls in the presence of phenolic ones. The generality of the reaction was demonstrated with a series of phenolic alcohols of dietary relevance (vanillol, hydroxytyrosol, epicatechin), providing an expeditious entry into a series of compounds of relevance for biomedical research, some of which previously available only by enzymatic methods