Latent curing of epoxy-thiol thermosets

Epoxy-thiol curing is a click reaction which allows quantitative yield of the end products. The base-catalyzed reaction is rapid at low temperatures so it is most often desirable to harness reactivity by using latent catalysts. In this work, we used triazabicyclodecene tetraphenylborate (TBD·HBPh4) as a photobase generator (PB). We activated the PB either thermally or by UV light and monitored reaction kinetics by DSC and FTIR methods. Depending on the catalytic system used, the rate of the thiol-epoxy reaction was ordered as follows: Neat base > UV activated PB > thermally activated PB > uncatalyzed system. A series of isothermal and non-isothermal DSC experiments were run on non-irradiated and irradiated samples in order to study the effect of PB content and UV irradiation duration on PB activation efficiency and latency/storage stability. The data from DSC were analyzed using model-free linear isoconversional methods to estimate kinetic parameters such as activation energies. In addition, the kinetics data for both activation methods were shown to be accurately represented by multi-term Kamal models. The storage stability of the systems were studied at room temperature and was shown to fit well to the predictions of the kinetic model.Postprint (author's final draft

Exploring the Intricacies of Integrating with a Port Community System

On the basis of an exploratory case study, this paper is intended to provide understanding on the intricacies associated with the integration of firms with a business sector information infrastructure (BSII) such as a port community system (PCS). Although there is some research on the implementation of PCS, these studies have rarely addressed the issue of integration of preexisting systems. We address this gap with a case study of a PCS in a Spanish port community, which, moreover, complements prior studies by adopting a processual socio-technical perspective on integration. Finally we elaborate implications relevant to the implementation of BSIIs

Cerca d’automorfismes i d’isomorfismes de grafs: algorismes i implementació

Treballs Finals de Grau de Matemàtiques, Facultat de Matemàtiques, Universitat de Barcelona, Any: 2013, Director: Antoni BensenyGraph Isomorphism problem (GIP) consists in constructing an efficient algorithm for testing whether two graphs are isomorphics and to find, if it exists, one isomorphism,i.e, to find a one-to-one, onto mapping from the set of vertexs of one graph to the set of vertexs of the other graph, so that the edges remain the same. GIP is one of the most interesting problems in Discrete Mathematics, it is essential for Graph Theory as well as for computational complexity theory. The problem has interest in the theoretical side, because it is not known if it is a P or NP-complete problem. On the one hand it is known that many classes of graphs admit polynomial time algorithms for isomorphism testing, such as rooted trees, planar graphs, circular graphs, graphs with bounded vertex degree, etc. On the other hand, the search for isomorphism complete problems has produced a large list of problems, such as bipartite graph isomorphism, regular graph isomorphism, complement graph isomorphism, automorphism orbits search, automorphism generators search, etc. So, GIP is a good candidate for an intermediate computational status between P and NP problems. From the practical point of view, GIP has many applica tions for science and technology: pattern recognition, data mining, computer vision, chemistry and VLSI layout validation. During the last decades many algorithms have been born to solve the problem, most of them based on Canonical labeling and direct backtracking, but Brendan McKay’s Nauty algorithm has stood up among the others because its fine performing. In 2011, José Luis López Presa et al. tested Nauty with some special graphs, Miyazaki’s graphs, and confirmed that it was very slow to find isomorphisms. So, they developed a new algorithm, Conauto, which attacks the problem in an original way, using special techniques to prune the automorphisms searching tree, to become one of the fastest algorithms today. The aim of this work is, on the one hand, to study and analyze the theoretical background the algorithm Conauto relies on and, on the other hand, to try to perform any improvement in some aspects: it has been implemented a graphical interface to visualize the partitions on the graphs and it has been performed two different algorithms to calculate the whole automorphism group of the graph starting from a set of generators; a first one based on brute force (strength) and a second one based on the Schreier-Sims algorithm. An algoritm that calculates all isomorphisms between two graphs, starting from one previous isomorphism and the whole automorphism group of one of the graphs, have also been implemented

Mechanical characterization of sol–gel epoxy-silylatedhyperbranched poly(ethyleneimine) coatings by meansof Depth Sensing Indentation methods

A series of hybrid epoxy-silica coatings were prepared from a synthesized hyperbranched poly(ethyleneimine) with ethoxysilyl groups at the chain ends and diglycidylether of bisphenol A in different proportions. The curing procedure was based in a first sol-gel reaction performed at 80 °C in a humid chamber followed by the anionic homopolymerization of epoxides initiated by 1-methylimidazole in an oven at 180 °C. The prepared coatings were characterized mechanically by means of Depth Sensing Indentation technique. The influence of physical ageing on indentation hardness has been evaluated. The kinetic of the delayed depth recovery has been analyzed using the phenomenological so-called Kohlrausch-Williams-Watts relaxation function. It has been found that silylated hyperbranched poly(ethyleneimine) improves simultaneously the mechanical coating performance and the elastic recovery.Postprint (author's final draft

Antiguedades celticas de la Isla de Menorca desde los tiempos mas remotos hasta el s. IV de la era cristiana

La hoja de grabado litografiado sobre Talayots o Torres redondas

Relacion de la Real Proclamacion de S.M. ... Rey Don Carlos IV : executada en la ciudad de Mahon ... en veinte y dos febrero de mil setecientos ochenta y nueve ...

Portada con orla tip., esc. calc. de la ciudad de Mahón "Grases fecit 1789" y letras doradas.En. páginas 12 grabado calc. de monedas: "Grases fecit 1789"Algunas páginas del texto a dos tintas