Alternancia/complementariedad en la ocupación de las cuevas de Alkerdi y Berroberría

Se aportan datos razonados de los motivos que explican la alternancia o el uso complementario de las cuevas de Alkerdi y Berroberría (Urdax, Navarra).------------Reasoned data are contributed of causes that they explain the complementary alternation or use of caves of Alkerdi and Berroberría (Urdax, Navarre)

The influence of copolymer composition on PLGA/nHA scaffolds´ cytotoxicity and in vitro degradation

The influence of copolymer composition on Poly(Lactide-co-Glycolide)/ nanohydroxyapatite (PLGA/nHA) composite scaffolds is studied in the context of bone tissue engineering and regenerative medicine. The composite scaffolds are fabricated by thermally-induced phase separation and the effect of bioactive nanoparticles on their in vitro degradation in phosphate-buffered solution at 37 °C is analyzed over eight weeks. The indirect cytotoxicity evaluation of the samples followed an adaptation of the ISO 10993-5 standard test method. Based on the measurement of their molecular weight, molar mass, pH, water absorption and dimensions, the porous scaffolds of PLGA with a lower lactide/glycolide (LA/GA) molar ratio degraded faster due to their higher hydrophilicity. All of the samples without and with HA are not cytotoxic, demonstrating their potential for tissue engineering applications.SGIker (UPV/EHU, MICINN, GV/EJ, ERDF and ESF) is really appreciated. This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013 and Grant SFRH/BD/111478/2015 (S.R). The authors acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R (Agencia Estatal de Investigación(AEI)/FEDER, Unión Europea(UE))info:eu-repo/semantics/publishedVersio

Crossover from superspin glass to superferromagnet in FexAg100-x nanostructured thin films ( 20 ≤ x ≤ 50 )

FexAg100?x granular thin films, with 20 x 50, have been prepared by the dc-magnetron sputtering deposition technique. With this technique we have been able to obtain samples comprising small Fe nanoparticles 2.5?3 nm embedded in a Ag matrix, remaining their size practically constant with increasing Fe content. Their magnetic behavior has been fully characterized by dc magnetic measurements between 5?350 K. They have revealed a crossover in the collective magnetic behavior of the Fe nanoparticles around a 35 at. %. Below such a concentration, a collective freezing of the magnetic moments is observed at low temperatures, while at high temperatures a transition, mainly mediated by dipolar interactions, to a magnetically disordered state is obtained. Above this concentration, direct exchange interactions overcome the dipolar magnetic interactions and a long-range order tends to prevail in the range of temperatures analyzed. ac magnetic measurements have indicated a crossover from a superspin glass x35 to a superferromagnetic x35 behavior for the magnetic moments of the Fe nanoparticles.This work was supported by the CICYT of Spain under Contracts No. MAT2008-06542-C04-02 and No. MAT2008- 06542-C04-04. SGIker technical support MEC, GV/EJ, European Social Fund is gratefully acknowledged. The financial support from the Basque Government Department of Education Project No. IT-347-07 is acknowledged

Assemblies of magnetite nanoparticles extracted from magnetotactic bacteria: A magnetic study

Self-assembly has emerged as a suitable technique for tuning the properties of nanoparticles. In this work, we report the self-assembly of magnetosomes assisted by an external magnetic field. The magnetosomes are magnetite nanoparticles biomineralized by magnetotactic bacteria Magnetospirillum gryphiswaldense. These nanoparticles present truncated cubo-octahedral morphology with a mean diameter of ˜36 nm and are surrounded by a lipid bilayer membrane with a thickness ˜2-4 nm. The use of the appropriate preparation conditions, such as initial colloidal concentration and magnetic fields applied during deposition allowed us to obtain very reproducible self-assembled 2D patterns. Homogeneous ensembles of magnetosomes onto silicon and carbon surfaces are composed of elongated structures in the form of wide chains that cover a large area of the substrates. Transmission electron microscopy image and off-axis electron holography showed the map of the stray magnetic fields produced by these assemblies. The induced magnetic anisotropy was analyzed by measuring the hysteresis loops of the assemblies at different angles in a magneto-optical Kerr effect magnetometer. The evolution of the coercive field and remanence verified the presence of well-defined patterns. The experimental results were analyzed on the based of a biaxial model

Proposal of an extended t-J Hamiltonian for high-Tc cuprates from ab initio calculations on embedded clusters

A series of accurate ab initio calculations on Cu_pO-q finite clusters, properly embedded on the Madelung potential of the infinite lattice, have been performed in order to determine the local effective interactions in the CuO_2 planes of La_{2-x}Sr_xCuO_4 compounds. The values of the first-neighbor interactions, magnetic coupling (J_{NN}=125 meV) and hopping integral (t_{NN}=-555 meV), have been confirmed. Important additional effects are evidenced, concerning essentially the second-neighbor hopping integral t_{NNN}=+110meV, the displacement of a singlet toward an adjacent colinear hole, h_{SD}^{abc}=-80 meV, a non-negligible hole-hole repulsion V_{NN}-V_{NNN}=0.8 eV and a strong anisotropic effect of the presence of an adjacent hole on the values of the first-neighbor interactions. The dependence of J_{NN} and t_{NN} on the position of neighbor hole(s) has been rationalized from the two-band model and checked from a series of additional ab initio calculations. An extended t-J model Hamiltonian has been proposed on the basis of these results. It is argued that the here-proposed three-body effects may play a role in the charge/spin separation observed in these compounds, that is, in the formation and dynamic of stripes.Comment: 24 pages, 4 figures, submitted to Phys. Rev.

First comprehensive contribution to medical ethnobotany of Western Pyrenees

<p>Abstract</p> <p>Background</p> <p>An ethnobotanical and medical study was carried out in the Navarre Pyrenees, an area known both for its high biological diversity and its cultural significance.</p> <p>As well as the compilation of an ethnopharmacological catalogue, a quantitative ethnobotanical comparison has been carried out in relation to the outcomes from other studies about the Pyrenees. A review of all drugs used in the area has also been carried out, through a study of the monographs published by the institutions and organizations responsible for the safety and efficacy of medicinal plants (WHO, ESCOP, and the E Commission of the German Department of Health) in order to ascertain the extent to which the Navarre Pyrenees ethnopharmacology has been officially evaluated.</p> <p>Methods</p> <p>Fieldwork was carried out over two years, from November 2004 to December 2006. During that time we interviewed 88 local people in 40 villages. Information was collected using semi-structured ethnobotanical interviews and the data was analyzed using quantitave indexes: Ethnobotonicity Index, Shannon-Wiener's Diversity, Equitability and The Informant Consensus Factor. The official review has been performed using the official monographs published by the WHO, ESCOP and the E Commission of the German Department of Health.</p> <p>Results</p> <p>The ethnobotanical and medical catalogue of the Navarre Pyrenees Area comprises 92 species, of which 39 have been mentioned by at least three interviewees. The quantitative ethnobotany results show lower values than those found in other studies about the Pyrenees; and 57.6% of the Pyrenees medical ethnobotany described does not figure in documents published by the above mentioned institutions.</p> <p>Conclusion</p> <p>The results show a reduction in the ethnobotanical and medical knowledge in the area of study, when compared to other studies carried out in the Pyrenees. Nevertheless, the use of several species that may be regarded as possible sources for pharmacological studies is reported here such as the bark of <it>Sambucus nigra</it>, the roots of <it>Fragaria vesca</it>, or the leaves of <it>Scrophularia nodosa</it>. These species are not currently approved by the WHO, ESCOP and the E Commission of the German Department of Health, institutions that, apart from encouraging the greater use of plants for medicinal purposes, may help in the design of development plans for these rural areas by validating their traditional medicine.</p