Hydrogen-induced microstructural changes of Pd films

The development of the microstructure in nanocrystalline, polycrystalline and epitaxial Pd films loaded with hydrogen is investigated. Structural changes in Pd films loaded with hydrogen were characterized by positron annihilation spectroscopy combined with electron microscopy and X-ray diffraction. It was found that hydrogen charging causes plastic deformation which leads to an increase of the defect density in all Pd films studied. Moreover, the formation of buckles was observed in nanocrystalline and polycrystalline Pd films loaded above a certain critical hydrogen concentration. Buckling leads to detachment of the film from the substrate and this is accompanied with in-plane stress relaxation and plastic deformation of the film.     

Catalytic activity evaluation for hydrogen production via autothermal reforming of methane

A nickel catalyst (5.75 wt.%) supported on gamma-alumina was evaluated through autothermal reforming of methane (ATR). The reforming process was pointed to hydrogen production, following thermodynamic and stoichiometric predictions. The catalyst was characterised by several methods including atomic absorption spectroscopy (AAS), B.E.T.-N₂, X-ray diffraction (XRD), scanning electron microscope (SEM) and thermal analyses (thermogravimetry, TG; derivate thermogravimetry, DTG; and differential thermal analysis, DTA). Experimental evaluations in a fixed-bed reactor (1023–1123 K, 1.00 bar, 150–400 cm³/min feed) presented methane conversions in the range of 40–65%. The effluent mixtures provided hydrogen yields in the range of 78–84%, carbon monoxide 3–14%, and carbon dioxide 5–18%. High molar H₂/CO ratios, ranging from 8 to 90, were obtained. Operating autothermal conditions (excess of steam, 1023–1123 K, 1.00 bar) provided low coke formation and high hydrogen selectivity (81%) for methane reforming.     

A Planning Model for the Fuerte-Carrizo Irrigation System, Mexico

A methodology is presented for planning the operation of the Fuerte-Carrizo irrigation system in northwest Mexico. The system has two storage dams, two irrigation districts, and water transfer capabilities between both dams. The methodology uses a combination of linear programming (LP) and simulation. The LP model maximizes the net return of the farmers, subject to restrictions of the system, availability of water and land, and water transfer relationships. The simulation model is programmed as a microcomputer interactive package simulating the performance of the system. The methodology has proven to be a useful tool to assist those responsible for the operation of the irrigation system.     

Thiophene as Internal Promoter of Selectivity for the Liquid Phase Hydrogenation of Citral Over Ru/KL Catalysts

The effect of thiophene (Th) addition, in the concentration range 0–6 ppm, on the performance of Ru/KL catalysts is analyzed for the liquid phase hydrogenation of citral at 323 K and 4 MPa. The results show a promoter effect of thiophene on the overall hydrogenation activity of the catalysts, with a maximum at 3 ppm concentration of Th. Particularly, it is evidenced an increase in the selectivity towards the hydrogenation of the carbonyl group of citral.     

Quantum complementarity and logical indeterminacy

Whenever a mathematical proposition to be proved requires more information than it is contained in an axiomatic system, it can neither be proved nor disproved, i.e. it is undecidable, or logically undetermined, within this axiomatic system. I will show that certain mathematical propositions on a d-valent function of a binary argument can be encoded in d-dimensional quantum states of mutually unbiased basis (MUB) sets, and truth values of the propositions can be tested in MUB measurements. I will then show that a proposition is undecidable within the system of axioms encoded in the state, if and only if the measurement associated with the proposition gives completely random outcomes.     

Fatty acid composition of selected roes from some marine species

Fifteen roes from different marine fish species available in Spain were analyzed in order to determine their fatty acid (FA) composition, especially the eicosapentaenoic acid (20:5n‐3, EPA) and docosahexaenoic acid (22:6n‐3, DHA) contents. Roes from Atlantic bonito (Sarda sarda), European squid (Loligo vulgaris), cuttlefish (Sepia spp.), lumpfish (Cyclopterus lumpus), European hake (Merluccius merluccius), Atlantic salmon (Salmo salar) and gonads of male Atlantic mackerel (Scomber scombrus) reached EPA + DHA amounts higher than 30% of the total FA, and among them, roes from lumpfish, European hake and salmon provide different FA type ratios that could make them adequate as dietary sources of EPA and DHA.     

Molecular interactions at biointerfaces: a study of lipid adsorption

The study of the behaviour of biointerfaces is of great interest because it enables us to gain a much better understanding of the interactions between different biological compounds. Superficial processes are strongly dependent on such interactions. In the present work, we have focused our attention on the adsorption of a cationic lipid onto different colloidal polymer systems. Subsequently, the coadsorption of this lipid and an immunoprotein (F(ab') ₂) was performed trying to achieve stable latex particles. The aim was to obtain a structured interface similar to that of a simple biological membrane. Mainly, we have placed emphasis on the study of interaction forces that govern lipid adsorption when we change the dielectric constant in the medium. In order to obtain homogeneous aqueous lipid solutions some ethanol was added to samples. The adsorption isotherms were carried out at different experimental conditions, changing the ethanol contents and the pH of the environment. Moreover, the electrokinetic behaviour and the colloidal stability of these biocomplexes were studied, and both yielded highly compatible results. The adsorption of lipid onto polymeric sorbents is an irreversible process that takes place rapidly. The preferential interaction between the lipid and polymeric surfaces is electrostatic. Only in those samples with low alcohol concentration, hydrophobic forces take place weakly. Lipid-surface interactions are influenced by the nature of buffer ions. The colloidal stability of the systems decreases as the amount of the adsorbed lipid is higher. Sequential coadsorption experiments showed that the lipid molecules adhere both to the polymer surface and to the previously adsorbed immunoprotein.