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Abstract: The structural and hydrogenation properties of the (Ti0.355V0.645)100−x M x (x =7, 14 and 21) alloys with M=Mn, Fe, Co and Ni and their hydrides have been investigated. The limit of solubility of the M element in the solid solution at constant Ti/V ratio (0.55) increases from Ni to Mn, respectively, from 7at.% to more than 14at.% at 1273K. For the single phase BCC alloys, the hydrogen capacities reach about 4wt.% at room temperature under 2MPa but the reversible capacity at 298K is low for the (Ti0.355V0.645)93M7 alloys. However, the cell volume reduction induced by the increasing substitution of the M element leads to a reversible capacity of 2wt.% at room temperature for the (Ti0.355V0.645)86Fe14 alloy. Moreover, the influence of the M element is observed on the equilibrium pressure since destabilization of the hydride is larger for Fe than Mn beyond geometrical consideration. Evolution of the structural parameters during absorption and desorption have been studied by neutron and X-ray diffraction for the Mn (x =7) and Fe (x =14) alloys, respectively. For the system (Ti0.355V0.645)93Mn7–H2, only one hydride is observed with a FCC-type structure (). The hydrogen sites have been determined by neutron diffraction for the fully charge dihydride (Ti0.355V0.645)93Mn7D1.88. For the system (Ti0.355V0.645)86M14–H2, the fully charged hydride exhibits a FCC-type structure () whereas the intermediate one shows a tetragonal symmetry (I4/mmm). The stability domain of the tetragonal phase ranges from 0.75 to 0.92H/M. [Copyright &y& Elsevier]

Abstract: Electrical vehicles (EV) powered by a fuel cell will need a buffer tank to supply hydrogen especially for cold start and/or to overcome the delayed response time in the hydrogen supply system (reformer, dehydrogenation, etc.). To allow hydrogen supply at low temperature, the crystallographic and thermodynamic properties of the system La0.55Y0.45Ni5– have been investigated. The pressure–composition–isotherm (PCI) curves have been carried out between 253 and 318 K. The compound La0.55Y0.45Ni5 can deliver 5.4 H/f.u. (1.3 wt.%) under 0.35 MPa at 253 K. At room temperature, between 0.6 and 3.3 H/f.u., a well-defined plateau is observed in the PCI curve. However, for capacity values larger than 3.3 H/f.u., a step is observed followed by a sloppy domain. Investigation by neutron diffraction at various states of charge has allowed determination of the La0.55Y0.45Ni5– phase diagram. The existence of an intermediate phase has been established. The crystal structures of the and phases have been determined. The occurrence of the phase could significantly increase the cycle life of the hydride by decreasing the constraints which are generated during absorption/desorption cycling as previously observed in other LaNi5-type systems. [Copyright &y& Elsevier]

Adsorption of deuterium gas in single-wall carbon nanotubes (SWNTs) with closed end, doped with potassium was simultaneously studied by adsorption isotherms and neutron diffraction in the range 18–300 K. Neutron diffraction has shown that doped SWNTs are only slightly intercalated by K ions so that empty cavities are preserved in between the tubes. At room temperature, the chemisorption of deuterium molecules was not observed in doped SWNTs bundles, but only in the KC8 graphite intercalation compound impurities. At low temperature, the isotherms analysis and neutron diffraction experiments have shown that D2 molecules are physisorbed in doped SWNTs in the free interstitial voids. [Copyright &y& Elsevier]

The short favorable period of time available for the growth in seasonal environments could constrain the resources allocation between growth and other life-history traits, and the short-term fitness benefits of increased growth rate may prevail over other functions. Accelerated growth rates have been associated with long-term deleterious consequences (e.g., decreased lifespan), and recently oxidative stress (the imbalance between pro-oxidants generation and antioxidant defenses) has been suggested as a mediator of these effects. Here, we examined the impact of elevation on growth rate and self-maintenance parameters (resting metabolism, oxidative damage, and antioxidant defenses) of coal tit chicks (Periparus ater). We predicted that the shorter favorable season at the higher-elevation site could lead to a reallocation of resources towards growth at the expense of self-maintenance processes. We found that chicks at high elevation grew significantly faster in terms of body mass and body size. Chicks from the high-elevation site presented higher resting metabolism, higher oxidative damage level, but similar antioxidant defenses, compared to low-elevation chicks. Interestingly, the chicks exhibiting the better antioxidant defenses at 7 days were also those with the highest resting metabolic rate, and the chicks that grew at the faster rate within the high-elevation site were those with the highest levels of oxidative damage on DNA. Our study supports the idea that increasing elevation leads to a higher growth rate in coal tit chicks, possibly in response to a shorter favorable season. In accordance with life-history theory, a bigger investment in growth was done at the expense of body maintenance, at least in terms of oxidative stress.

North Western European populations of White Storks (Ciconia ciconia) appear to have been saved from extinction by settling, i.e. stopping migration. Settled storks exposed to winter conditions must cope with periods of potentially high energy demands that would otherwise be avoided by the migration process. Doubly labeled water (DLW) was therefore used to examine the seasonal variation (summer vs winter) in daily energy expenditure (DEE) and the body composition of adult and immature storks of both sexes. Male White Storks showed a higher DEE over the winter period than in summer compared with females; in particular, immature males exhibited greater energy expenditure in winter than adult males. Thus, the DEE did not significantly differ between summer and winter (except for immature males), reflecting an absence of thermoregulation cost in winter. For both age classes, total body mass increased in winter, which was mainly due to an increase in fat mass. Adult storks were 5% heavier than immature storks. The sexes differed in body mass, with males weighing significantly more than females by 11%. Mean LBM (lean body mass) was 8.5% higher in adults than in immatures, and was 11.5% higher in males compared with females. Between their first and second summers, immatures accumulated a lean body mass to finally reach the same values as adults, indicating a phase of muscle development. The mean fat mass of the storks did not differ between age classes or between sexes. Based on physiological parameters, this study shows that settled White Storks are able to cope with mild winter periods when they are artificially provided with food. In a view to preserve favourable habitats for this species, it is therefore necessary to decide on a plan of action for breeding areas.