Nanogranular MgB2 thin films on SiC buffered Si substrates prepared by in-situ method

MgB2 thin films were deposited on SiC buffered Si substrates by sequential electron beam evaporation of B-Mg bilayer followed by in-situ annealing. The application of a SiC buffer layer enables the maximum annealing temperature of 830 C. The Transmission Electron Microscopy analysis confirms the growth of a nanogranular MgB2 film and the presence of a Mg2Si compound at the surface of the film. The 150-200 nm thick films show a maximum zero resistance critical temperature TC0 above 37 K and a critical current density JC ~ 106 A/cm2 at 11K.Comment: 7 pages, 6 figures, submitted to Applied Physics Letter

Milk Iodine Content in Slovakia

The aim of this work was to map actual iodine status and its seasonal differences in raw milk of dairy cows, sheep, and goats in various regions of Slovakia. Iodine concentrations were determined in 457 samples of raw milk from dairy cows, 78 samples of sheep, and 16 samples of goat milk collected in various regions of Slovakia from 2002 to 2007. Among all the 457 samples of bovine milk, iodine content below 50 μg l-1 was recorded in 114 samples (24.94%); 294 samples (64.33%) ranged between 50 and 200 μg l-1; 19 samples (4.16%) from 200 to 500 μg l-1; 17 samples (3.72%) between 500 and 1 000 μg l-1, and 13 samples (2.85%) showed iodine concentrations over 1 000 μg l-1. regional concentrations showed the highest values in the Western, then Middle and Eastern Slovakia, and the lowest values in Northern Slovakia (p p -1 in 49 sheep (62.8%) and in 6 goats below 60 μg l-1 (37.5%), which are indicative of iodine deficiency. When comparing seasonal differences, sheep and goat milk had higher iodine content during the winter feeding period, however, in dairy cows we recorded the opposite ratio. Except for goat milk (p < 0.01) the seasonal differences were not significant

Estimation of the thermal diffusivity in a large electroceramic body by an invere method

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.We investigate the temperature dependence of the thermal diffusivity for a large ceramic body of a cylindrical shape during firing up to 900 °C. The body was made of a ceramic material used in the production of electroporcelain insulators. We describe the corresponding heat transfer by the standard heat equation and solve the inverse problem by the Levenberg-Marquardt method. The results show that the method allows one to detect the physical-chemical processes occurring in the material during firing, namely, the liberation of physically bound water in the range up to 250 °C, the phase transformation of kaolinite into metakaolinite (dehydroxyla-tion) in the range ~ 450 °C – 650 °C, and solid-state sintering starting at ~ 700 °C.cf201

Clustering in ferronematics : The effect of magnetic collective ordering

Clustering of magnetic nanoparticles can dramatically change their collective magnetic properties, and it consequently may influence their performance in biomedical and technological applications. Owing to tailored surface modification of magnetic particles such composites represent stable systems. Here, we report ferronematic mixtures that contain anisotropic clusters of mesogen-hybridized cobalt ferrite nanoparticles dispersed in liquid crystal host studied by different experimental methods—magnetization measurements, small-angle X-ray scattering (SAXS), small-angle neutron scattering (SANS), and capacitance measurements. These measurements reveal non-monotonic dependencies of magnetization curves and the Fréedericksz transition on the magnetic nanoparticles concentration. This can be explained by the formation of clusters, whose structures were determined by SAXS measurements. Complementary to the magnetization measurements, SANS measurements of the samples were performed for different magnetic field strengths to obtain information on the orientation of the liquid crystal molecules. We demonstrated that such hybrid materials offer new avenues for tunable materials

Synthesis of fluorosugar reagents for the construction of well-defined fluoroglycoproteins.

2-Deoxy-2-fluoroglycosyl iodides are privileged glycosyl donors for the stereoselective preparation of 1-Nu-β-fluorosugars, which are useful reagents for chemical site-selective protein glycosylation. Ready access to such β-fluorosugars enables the mild and efficient construction of well-defined fluoroglycoproteins.We thank the European Commission (Marie Curie CIG, O.B. and G.J.L.B.), MICINN, Spain (Juan de la Cierva Fellowship, O.B.), MINECO, Spain (CTQ2011-22872BQU) and Generalitat de Catalunya (M.S.) for generous financial support. We also thank Mr. Adrià Cardona-Benages (URV) for technical assis-tance. G.J.L.B. thanks the Royal Society (University Research Fellowship), Fundação para a Ciência a Tecnologia, Portugal (FCT Investigator), and the EPSRC for funding.This is the final version of the article. It first appeared from ACS via http://pubs.acs.org/doi/abs/10.1021/acs.orglett.5b01259

Nucleation of superconductivity and vortex matter in superconductor - ferromagnet hybrids

The theoretical and experimental results concerning the thermodynamical and low-frequency transport properties of hybrid structures, consisting of spatially-separated conventional low-temperature superconductor (S) and ferromagnet (F), is reviewed. Since the superconducting and ferromagnetic parts are assumed to be electrically insulated, no proximity effect is present and thus the interaction between both subsystems is through their respective magnetic stray fields. Depending on the temperature range and the value of the external field H_{ext}, different behavior of such S/F hybrids is anticipated. Rather close to the superconducting phase transition line, when the superconducting state is only weakly developed, the magnetization of the ferromagnet is solely determined by the magnetic history of the system and it is not influenced by the field generated by the supercurrents. In contrast to that, the nonuniform magnetic field pattern, induced by the ferromagnet, strongly affect the nucleation of superconductivity leading to an exotic dependence of the critical temperature T_{c} on H_{ext}. Deeper in the superconducting state the effect of the screening currents cannot be neglected anymore. In this region of the phase diagram various aspects of the interaction between vortices and magnetic inhomogeneities are discussed. In the last section we briefly summarize the physics of S/F hybrids when the magnetization of the ferromagnet is no longer fixed but can change under the influence of the superconducting currents. As a consequence, the superconductor and ferromagnet become truly coupled and the equilibrium configuration of this "soft" S/F hybrids requires rearrangements of both, superconducting and ferromagnetic characteristics, as compared with "hard" S/F structures.Comment: Topical review, submitted to Supercond. Sci. Tech., 67 pages, 33 figures, 439 reference

Ecological divergence of Chaetopteryx rugulosa species complex (Insecta, Trichoptera) linked to climatic niche diversification

Climate is often considered to be an important, but indirect driver of speciation. Indeed, environmental factors may contribute to the formation of biodiversity, but to date this crucial relationship remains largely unexplored. Here we investigate the possible role of climate, geological factors, and biogeographical processes in the formation of a freshwater insect species group, the Chaetopteryx rugulosa species complex (Trichoptera) in the Western Balkans. We used multi-locus DNA sequence data to establish a dated phylogenetic hypothesis for the group. The comparison of the dated phylogeny with the geological history of the Western Balkans shows that lineage formation coincided with major past Earth surface and climatic events in the region. By reconstructing present-day habitat conditions (climate, bedrock geology), we show that the lineages of C. rugulosa species complex have distinct climatic but not bedrock geological niches. Without exception, all splits associated with Pliocene/Pleistocene transition led to independent, parallel split into ‘warm’ and ‘cold’ sister lineages. This indicates a non-random diversification on the C. rugulosa species complex associated with late Pliocene climate in the region. We interpreted the results as the diversification of the species complex were mainly driven by ecological diversification linked to past climate change, along with geographical isolation