Jaume Serra Hunter : el pensament a la vida

Exposaré molt breument les dades biografiques, . les obres de Jaume Serra Hunter a que he tingut accés i una bibliografia, ben poca, sobre la seva personalitat. En una primera part estudiaré el programa de Serra Hunter, tal com es formula a *Idealitat, Metafísica, Espiritualisme)) , i d'altres escrits posteriors que el complementen. En una segona part parlaré del seu darrer llibre El pensament i la vida, que dóna el títol d'aquesta conferencia, especialment del que diu sobre l'home i sobre el coneixement; una tercera part sera dedicada als deixebles de Serra Hunter

Effects of hydroxyapatite (0001) Ca2+/Mg2+ substitution on adsorbed D-ribose ring puckering

Advanced Molecular Dynamics (MD) simulation protocols have been used to assess the ring puckering of cyclic D-ribose when the sugar is adsorbed on the most stable (0001) facet of calcium hydroxyapatite (HAp). In addition, sugar¿mineral interactions, which are crucial for transfection processes and prebiotic chemistry, have been studied for systems in which the Ca2+ ions of the above mentioned HAp facet were totally or partially replaced by Mg2+. The latter replacement is spatially and quantitatively limited and has been found to cause important alterations in the conformational behavior of D-ribose that are similar to those suffered in hairpin RNA from A to B helical structures. Accordingly, replacement of Ca2+ by Mg2+ has a dramatic effect on the functionality of the nucleic acid. These changes have been related to both the substitution site on the surface and the amount of ions. Our results show that when replacement by Mg2+ occurs in OH--coordinated Ca2+ ions, Mg2+¿D-ribose interactions are strong enough to prevent the interactions between the hydroxyl groups of the sugar and the remaining Ca2+ ions.Peer ReviewedPostprint (published version

Creative accounting in Spain : some evidence from Spanish quoted companies

The nature and incidence of earnings management practices have been examined in many research studies, especially in the United States. Research into such practices in Europe, and specifically in Spain has been less common. This paper makes a contribution to the existing literature by offering an analysis of certain features of Spanish accounting that can be classified as earnings management. The population of companies under review comprises those included in the IBEX-35 index, and so includes the largest companies in Spain. The effects upon earnings of four commonly encountered features in Spanish accounting practice are examined and quantified: audit report qualifications, special authorisations to override accounting regulation, changes in accounting policy and extraordinary items. The results of the analysis show that net earnings are affected to a significant extent by these items. The paper concludes that these relatively overt forms of earnings management are employed in the financial statements of several leading Spanish companies. While a reduction in the level of options offered by accounting regulation may help to reduce the incidence of earnings management, it is noted that a tightening of standards in one area tends to simply shift the location of earnings management. Remedial measures should, therefore, also include improvements in supervision

Accions metabòliques de la vitamina D molt més enllà del que podíem imaginar fa uns deu anys

La vitamina D és una peça clau en la regulació de l'homeòstasi mineral, protegeix la integritat de l'os i modula el creixement, i la seva deficiència és un problema de salut pública avui dia. Fora de l'os la vitamina D també ha estat associada amb efectes metabòlics, i s'han publicat en els últims anys múltiples estudis que demostren la relació de nivells baixos de vitamina D i obesitat. La concentració de vitamina D està associada a adipositat, però diversos estudis suggereixen que la deficiència de vitamina D pot ser un factor independent relacionat amb la patogènesi de comorbiditats associades a l'obesitat. En aquest article volem revisar la fisiopatologia de la deficiència de la vitamina D amb la seva associació amb l'obesitat i el paper que en representa el dèficit en les comorbiditats relacionades amb l'obesitat.The vitamin D is key in the regulation of the mineral homeostasis, protecting the integrity of the bone and modulating its growth. Its deficiency is currently a public health problem. Out of the bone the vitamin D has been associated with metabolic effects. Recent studies have demonstrated the relation between low levels of vitamin D and obesity. The concentration of vitamin D is associated with adiposity, but several studies suggest that the deficiency of vitamin D can be an independent factor related to the pathogenesis of comorbidities associated with the obesity. In this article, the pathophysiology of vitamin D deficiency and its association with obesity and comorbidities related with obesity are reviewed

Distribution of dopant ions around poly(3,4-ethylenedioxythiophene) chains: a theoretical study

The effect of counterions and multiple polymer chains on the properties and structure of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with ClO4- has been examined using density functional theory (DFT) calculations with periodic boundary conditions (PBCs). Calculations on a one-dimensional periodic model with four explicit polymer repeat units and two ClO4- molecules indicate that the latter are separated as much as possible, with the salt structure and band gap obtained from such ClO4- distribution being in excellent agreement with those determined experimentally. On the other hand, DFT calculations on periodic models that include two chains indicate that neighboring PEDOT chains are shifted along the molecular axis by a half of the repeat unit length, with dopant ions intercalated between the polymer molecules acting as cement. In order to support these structural features, classical molecular dynamics (MD) simulations have been performed on a multiphasic system consisting of 69 explicit PEDOT chains anchored onto a steel surface, explicit ClO4- anions embedded in the polymer matrix, and an acetonitrile phase layer onto the polymer matrix. Analyses of the radial distribution functions indicate that the all-anti conformation, the relative disposition of adjacent PEDOT chains and the distribution of ClO4- dopant ions are fully consistent with periodic DFT predictions. The agreement between two such different methodologies allows reinforcing the microscopic understanding of the PEDOT film structure.Peer ReviewedPostprint (author's final draft

Heterochirality Restricts the Self-Assembly of Phenylalanine Dipeptides Capped with Highly Aromatic Groups

The influence of stereochemistry on the self-assembly of phenylalanine (Phe) dipeptides bearing aromatic fluorenyl groups at both the N- and C-termini (Fmoc, OFm) has been investigated. For this purpose, Fmoc–d-Phe–l-Phe–OFm and Fmoc–l-Phe–l-Phe–OFm have been examined considering a wide variety of solvents, which differ in dielectric constant and volatility. Results reveal that replacement of l-Phe by d-Phe has a major impact on the self-assembly propensities, restricting drastically the structural diversity and polymorphism shown by the homochiral dipeptide. Thus, the analogous heterochiral dipeptide shows a great propensity to form micro/nanofibers, independently of the environmental conditions. Theoretical calculations revealed that the stability of antiparallel disposition is much higher (a factor of ca. 15) for Fmoc–d-Phe–l-Phe–OFm than that for Fmoc–l-Phe–l-Phe–OFm, which has been attributed to the hydrophobic core formed in the former. Overall, results suggest that control of the backbone chirality is a potent and versatile strategy to drive and finely tune the self-assembly propensities of highly aromatic peptides.This work was supported by MINECO (RTI2018-098951-B-I00, RTI2018-101827-B-I00, and CTQ2013-40855-R), AGAUR (2017SGR359 and 2017SGR373), and Gobierno de Aragon (research group Aminoacidos y Peptidos E19_20R). Support for the research of C.A. was received through the prize “ICREA Academia” for excellence in research funded by the Generalitat de Catalunya

Analysis of nitrogen fixation by a catalyst capable of transforming N2, CO2 and CH4 into amino acids under mild reactions conditions

The processes related to the fixation of nitrogen ina catalyst able to produce glycine and alanine from a N2, CO2and CH4gas mixture at mild reaction conditions have been studied by combining experimental and theoretical investigations.Results have allowed to understand the role of different elements of the catalyst, which is constituted by permanently polarized hydroxyapatite (p-HAp), zirconia, and aminotris(methylenephosphonic acid)(ATMP). ATMP attractsN2moleculestowards the surface,maintainingthem close to the zirconiaand p-HAp componentsthatare the most active from a catalytic point of view. On the other hand, the associative mechanismisthermodynamicallyfavouredunder mild reaction conditionswith respect to the dissociative one,whichis limited by the barrier associated to the N–Nbondcleavage. Because this reaction mechanism is similar to that employed in the nitrogen fixation bynitrogenase enzymes, thesefindingsprovide an opportunity to designnew bioinspired catalystsPostprint (author's final draft