C. de la Fuente

Soil C and N mineralisation and agricultural value of the products of an anaerobic digestion system

Anaerobic digestion is currently considered a valuable technology for recycling of cattle slurry due to the production of biogas, a renewable source of energy. However, an appropriate management of the waste generated from anaerobic co-digestion of cattle slurry (digestate) is needed for the sustainability of the process. This paper shows the effects provoked on soil C and N mineralisation processes and on microbial biomass due to the addition of the digestate, the liquid and solid fractions obtained after separation of the digestate and the composted solid fraction of the digestate, in comparison with the effects of the non-digested cattle slurry. Composting was a very effective way of recycling the digestate, producing highly stable (mineralised-C reached only 3% of the added total organic-C) and hygienised material with an elevated fertilising potential (the net-N mineralisation accounted for 2% of total-N from compost). The agricultural use of cattle slurry, the digestate and the separated fractions should take into account their effects on soil C and N cycles: high decomposition rate (ranging from 25% to 50% of total organic-C) and partial N immobilisation in the soil.

Implications of the use of As-rich groundwater for agricultural purposes and the effects of soil amendments on as solubility.

An agricultural site in Segovia province (Spain) contains high levels of arsenic (As) of geological origin in its groundwater, which is used intensively for irrigation. Crops, irrigation waters, and soils were analyzed to evaluate the occurrence of As in this area and its potential impact on the food chain. High As mobility was found in the agricultural soils, related to the application of As in the irrigation waters (14.8-280 μg As L(-1)) and the general alkaline and sandy character of these soils, which imposes a low capacity for As sorption and therefore enhances plant uptake. The use of amendments can also affect the solubility of As in these soils. Evidence for this was evaluated based on a study of the effect of organic (compost) and inorganic (iron oxides-rich rolling mill scale and phosphate fertilizer) amendments. Arsenic solubility in soil and plant uptake were high, but not significantly affected by organic matter or phosphate addition, while As immobilization was associated with addition of iron oxides with the rolling mill scale, although this did not result in a decrease of As uptake by the tested plants.

Strong interfacial magnetoelastic stress in holmium - lutetium (0001) superlattices

The saturation magnetoelastic stress (MS), , breaking the basal plane cylindrical symmetry of the hexagonal structure, has been measured for the series of superlattices (n = 8 to 85 atomic planes, with separation c/2). The MS was directly measured using a low-temperature cantilever technique. The Ho block MSs in the superlattices are larger than in an Ho film of A thickness and in bulk Ho. An analysis accounting for the contributions to coming from: the volume, , the interface, with magnetoelastic parameter , and the epitaxial strain shows that the interfacial magnetoelastic stress is strong, up to about six times larger than for n = 8, and of the opposite sign.

Magnetoelastic study of Ho/Y and Ho/Lu metallic superlattices

Abstract Magnetoelastic stress measurements in Ho/Y and Ho/Lu superlattices were performed by using a capacitive cantilever technique. The magnetic phase diagrams obtained from in-field transitions observed in the stress isotherms show helical, fan and ferromagnetic phases. At zero-field, the ferromagnetic phase is suppressed in Ho/Y and stabilised in Ho/Lu. Magnetoelastic coupling coefficients corresponding to the breaking of the cylindrical symmetry of the basal plane have been determined. Surface magnetostriction is observed for {Ho 31 Lu 19 } 50 .

On the instability of the Mn magnetic moment under applied magnetic field in TbMn2

Abstract Magnetostriction measurements under high steady magnetic field up to 12 T have been performed between 300 and 4.2 K, in order to confirm the instability of the local magnetic moment of the Mn atoms, μMn, in TbMn2 compound. From these measurements the existence of a critical magnetic field which suppresses μMn has been observed.

Magnetoelastic study in Lu2Fe17

The magnetostriction of Lu2Fe17 single crystal has been measured along the main , and hexagonal axes between 4 and 295 K by applying strong pulsed magnetic fields along the easy -axis. The irreducible strains, α,1 (volume) and α,2 (c/a-ratio), were obtained. The corresponding magnetoelastic parameters and elastic constants were calculated through FLAPW approach on DFT. These calculations are analysed at the same time with the experimental results to obtain information about the origin of the two-ion magnetoelastic contributions.

Violation of the Zener power law for linear magnetostriction in the weak random anisotropy magnets

The linear magnetostriction has been measured in the intermetallic compounds. The Zener power law, which gives as proportional to the third power of the reduced magnetization, is found to be valid in the ferromagnetic phase of . For x < 1 the compounds are weak random anisotropy magnets, and in the quasisaturated regime induced by a magnetic field is still proportional to , but the exponent p is smaller than three. p increases with the field and approaches three in the high-field limit (12 T). A relation between the violation of the Zener power law and the reduction of the magnetization in the random anisotropy systems is derived, and is compared with the experimental results.