Víctor Martínez Junza

Escola Universitària Salesiana de Sarrià | EUSS

This paper focuses on the study of discontinuities in the teaching of mathematics in engineering within the framework of the anthropological theory of didactics (ATD) and, in particular, attempts to characterize the internal discontinuity between the teaching of mathematics and the role of mathematical activity in engineering subjects through an in...

A simple approach for the functionalization of cylindrically shaped zeolite L crystals with iron oxide magnetic nanoparticles is reported. These functionalized zeolites can be aligned very easily by applying a magnetic field in solution, on different substrates, and in a polymeric matrix. The aligned zeolite loaded with fluorescent dyes are anisotr...

Four different riboflavin (RF) derivatives, two electronically modified compounds (1- and 5-deazariboflavin, 1DRF and 5DRF) and two sterically modified compounds (7,8-didemethyl- and 8-isopropylriboflavin, DMRF and iprRF), were subjected to a combination of time-resolved measurements (absorption and fluorescence) and high-level quantum chemical inv...

Biosubstrate-sensitizer binding is one of the factors that enhances the type-I mechanism over the type-II in the whole photodynamic process. 2,7,12,17-Tetraphenylporphycene (TPPo), a second-generation photosensitizer, is a hydrophobic compound with good photophysical properties for photodynamic therapy applications that has proved its ability for t...

A small contraction concomitant with the relaxation of the protein in ca. 3 mus is observed upon ns-laser excitation at 455 nm of the Cys69Ala (C69A) mutant of flavodoxin II from Azotobacter vinelandii. This constitutes another example of detection of a UV-vis silent transient species through a photocalorimetric technique. The contraction is attrib...

Nanosecond transient absorption spectroscopy has been used to study reaction centre (RC) chlorophyll triplet quenching by carotenoid in intact photosystem II cores from T. elongatus with closed RCs. We found a triplet beta-carotene ((3)Car) signal (absorption difference maximum at 530 nm) that is sensitized by the RC chlorophyll (Chl) triplet with...

Two ²-carotenes are located in the D1–D2 reaction center (RC) of photosystem II (PSII) in the X-ray structure (Loll et al. 2005). Despite the presence of these ²-carotenes and a high yield of reaction center (RC) triplet chlorophyll (Chl) production, no Chl triplet quenching by ²- carotene has been observed so far in the RC of PS II (see Telfer 200...

The enthalpy change, DeltaTH, and volume change, DeltaTV, associated with triplet state formation upon excitation of free-base meso-tetra-(4-sulfonatophenyl)porphyrin, TSPP4-, its Zn derivative, ZnTSPP4-, and meso-tetra-(4-carboxyphenyl)porphyrin, TCPP4-, were obtained in aqueous solutions by the application of laser-induced optoacoustics spectrosc...

Time-resolved laser-induced optoacoustic spectroscopy was used for the determination of the enthalpy, ΔTH, and structural volume changes, ΔTV, concomitant with triplet state formation upon excitation of meso-tetrakis(4-sulfonatophenyl)porphyrin, TSPP4-, as well as with the triplet state electron-transfer (ET) quenching by benzoquinone, BQ (ΔRH and...

Photophysical studies with semi-rigid, 1, and flexible, 2, donor–bridge–acceptor (D–b–A2+) molecules with D a porphyrin and A2+ a methyl viologen moiety, were performed in neat polar solvents as well as included in surfactant (DTAB) aqueous and in reverse AOT/n-alkane micelles. The micelles acted as nanoreactors for the photoinduced electron transf...

The thermodynamic parameters for the formation of the free radicals upon electron transfer quenching of the flavin triplet state (3FMN) by tryptophan and tyrosine, Delta(FR)H and Delta(FR)V, were obtained in aqueous solution by the application of laser-induced optoacoustic spectroscopy at various temperatures. The Delta(FR)H and Delta(FR)V values i...