244 research outputs found

    Room temperature ferromagnetic-like behavior in Mn-implanted and post-annealed InAs layers deposited by Molecular Beam Epitaxy

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    We report on the magnetic and structural properties of Ar and Mn implanted InAs epitaxial films grown on GaAs (100) by Molecular Beam Epitaxy (MBE) and the effect of Rapid Thermal Annealing (RTA) for 30 seconds at 750C. Channeling Particle Induced X- ray Emission (PIXE) experiments reveal that after Mn implantation almost all Mn atoms are subsbtitutional in the In-site of the InAs lattice, like in a diluted magnetic semiconductor (DMS). All of these samples show diamagnetic behavior. But, after RTA treatment the Mn-InAs films exhibit room-temperature magnetism. According to PIXE measurements the Mn atoms are no longer substitutional. When the same set of experiments were performed with As as implantation ion all of the layers present diamagnetism without exception. This indicates that the appearance of room-temperature ferromagnetic-like behavior in the Mn-InAs-RTA layer is not related to lattice disorder produce during implantation, but to a Mn reaction produced after a short thermal treatment. X-ray diffraction patterns (XRD) and Rutherford Back Scattering (RBS) measurements evidence the segregation of an oxygen deficient-MnO2 phase (nominally MnO1.94) in the Mn-InAs-RTA epitaxial layers which might be on the origin of room temperature ferromagnetic-like response observed.Comment: 16 pages, 5 figures. Acepted in J. Appl. Phy

    Large current-induced broadening of the superconducting transition in Mo/Au transition edge sensors

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    The R(T, I) shape of the superconducting transition in transition edge sensors (TESs) is of crucial importance to determine their ultimate performance. This paper reports a study of the temperature and current dependences of the transition of Mo/Au TESs, focused on the low resistance region, where these devices preferentially operate. A large broadening of the transition is observed when increasing the applied current. An empirical analytic expression for R(T, I) is found, which describes the transition of devices with different critical temperatures, from R = 0 up to at least 30% R-n (in some cases nearly 80% R-n). Several mechanisms for this behaviour are considered; results show that a current assisted vortex pair unbinding mechanism (Berezinskii-Kosterlitz-Thouless transition) could be the possible origin for this behaviour. Finally, the consequences of the current-induced transition broadening for TES properties and operation are outlined

    A model of maxilla resection to test new hybrid implants:macroporous titanium and tissue engineering elements

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    Maxillary bone loss in commonly found in humans, due to bone ageing, tooth loos, periodontal disease and, more severely, to trauma, radiotherapy and tumor resection. Masillofacial reconstructive surgery is a still unmet clinical demand, available therapies include grafting of autologous or heterologous bone tissue and/or the implantation of metallic plates, buy these treatments are still unable to resume form and function. The emrgence of 3D-printing technology applied to metal alloys now allows the manufacturing of customized, patient-tailored prosthetic implants. However, poor bone quiality at the implant site due to ageing or disease still hamper proper osseointegration. By combining Electron Beam Melting metal sintering and tissue engineering, we are developing hybrid maxillofacial implants, wher a metal framework of Ti6Al4V alloy confers both and appropiaate shape and mechanical stabilty, while stem cells and osteogenic molecules stimulate bone growth into the metal framework, thus pormoting osseointegration. We hereby present the in vitro work driving to the development of our hybrid maxillofacial prostheses, as well as the setting up of an in vivo model of complete maxilla full resection, created in order to test the prostheses in a preclinical studyUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Spirometric Assessment of Lung Transplant Patients: One Year Follow-Up

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    OBJECTIVE: The purpose of this study was to compare spirometry data between patients who underwent single-lung or double-lung transplantation the first year after transplantation. INTRODUCTION: Lung transplantation, which was initially described as an experimental method in 1963, has become a therapeutic option for patients with advanced pulmonary diseases due to improvements in organ conservation, surgical technique, immunosuppressive therapy and treatment of post-operative infections. METHODS: We retrospectively reviewed the records of the 39 patients who received lung transplantation in our institution between August 2003 and August 2006. Twenty-nine patients survived one year post-transplantation, and all of them were followed. RESULTS: The increase in lung function in the double-lung transplant group was more substantial than that of the single-lung transplant group, exhibiting a statistical difference from the 1st month in both the forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC) in comparison to the pre-transplant values (p <0.05). Comparison between double-lung transplant and single lung-transplant groups of emphysema patients demonstrated a significant difference in lung function beginning in the 3rd month after transplantation. DISCUSSION: The analyses of the whole group of transplant recipients and the sub-group of emphysema patients suggest the superiority of bilateral transplant over the unilateral alternative. Although the pre-transplant values of lung function were worse in the double-lung group, this difference was no longer significant in the subsequent months after surgery. CONCLUSION: Although both groups demonstrated functional improvement after transplantation, there was a clear tendency to greater improvement in FVC and FEV1 in the bilateral transplant group. Among our subjects, double-lung transplantation improved lung function

    Thickness dependence of critical temperature in Mo/Au bilayers

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    We report on the sensitivity of the superconducting critical temperature (TC) to layer thickness, as well as on TC reproducibility in Mo/Au bilayers. Resistivity measurements on samples with a fixed Au thickness (dAu) and Mo thickness (dMo) ranging from 50 to 250 nm, and with a fixed dMo and different dAu thickness are shown. Experimental data are discussed in the framework of Martinis model, whose application to samples with dAu above their coherence length is analysed in detail. Results show a good coupling between normal and superconducting layers and excellent TC reproducibility, allowing to accurately correlate Mo layer thickness and bilayer TC

    Estudio epidemiológico de la litiasis en Armilla (Granada) (T. C)

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    In this study we have pointed out the incidence of the lithiasis at a whole poblation and as the town of Armilla (Granada - Spain). We have shown the relationships between the nephritic calculi and several parameters such as Age. sexo etc. We have also compared out results with other of differents authors several parts of the world.Se estudia la incidencia de la litiasis renal en población completa. La unidad elegida ha sido Armilla y en este estudio además de relacionar la incidencia con diversos parámetros, tales como edad, sexo, recidivas, etc., se comparan los resultados obtenidos con los de otros autores en distintas partes del mundo

    Estudio epidemiológico de la litiasis en Armilla (Granada) (T. C)

    Get PDF
    Se estudia la incidencia de la litiasis renal en población completa. La unidad elegida ha sido Armilla y en este estudio además de relacionar la incidencia con diversos parámetros, tales como edad, sexo, recidivas, etc., se comparan los resultados obtenidos con los de otros autores en distintas partes del mundo.In this study we have pointed out the incidence of the lithiasis at a whole poblation and as the town of Armilla (Granada - Spain). We have shown the relationships between the nephritic calculi and several parameters such as Age. sex. etc. We have also compared out results with other of differents authors several parts of the world

    Fabrication process of Mo/Au TES at RT

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    We report on the fabrication details of TES based on Mo/Au bilayers. The Mo layer is deposited by radio frequency (RF) sputtering and capped with a sputter deposited thin Au protection layer. Afterwards, a second Au layer of suitable (lower) resistivity is deposited ex‐situ by e‐beam evaporation, until completion of the total desired Au thickness. The deposition was performed at room temperature (RT) on LPCVD Si3 N4 membranes. Such a deposition procedure is very reproducible and allow controlling the critical temperature (Tc) and normal electrical resistance (RN ) of the Mo/Au bilayer. The process is optimized to achieve low stress bilayers, thus avoiding the undesirable curvature of the membranes. Bilayers are patterned using photolithographic techniques and wet etching procedures. Mo superconducting paths are used to contact the Mo/Au bilayers, thus ensuring good electrical conductivity and thermal isolation. The entire fabrication process let to stable and reproducible sensors with required and tunable functional propertie

    Differences and similarities of stellar populations in LAEs and LBGs at z~3.4-6.8

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    Lyman alpha emitters (LAEs) and Lyman break galaxies (LBGs) represent the most common groups of star-forming galaxies at high z, and the differences between their inherent stellar populations (SPs) are a key factor in understanding early galaxy formation and evolution. We have run a set of SP burst-like models for a sample of 1558 sources at 3.4 < z < 6.8 from the Survey for High-z Absorption Red and Dead Sources (SHARDS) over the GOODS-N field. This work focuses on the differences between the three different observational subfamilies of our sample: LAE–LBGs, no-Ly α LBGs, and pure LAEs. Single and double SP synthetic spectra were used to model the spectral energy distributions, adopting a Bayesian information criterion to analyze under which situations a second SP is required. We find that the sources are well modelled using a single SP in ∼79 per cent of the cases. The best models suggest that pure LAEs are typically young low-mass galaxies (⁠t∼26+41−25 Myr; Mstar∼5.6+12.0−5.5×108 M⊙⁠), undergoing one of their first bursts of star formation. On the other hand, no-Ly α LBGs require older SPs (t ∼ 71 ± 12 Myr), and they are substantially more massive (Mstar ∼ 3.5 ± 1.1 × 109 M⊙). LAE–LBGs appear as the subgroup that more frequently needs the addition of a second SP, representing an old and massive galaxy caught in a strong recent star-forming episode. The relative number of sources found from each subfamily at each z supports an evolutionary scenario from pure LAEs and single SP LAE–LBGs to more massive LBGs. Stellar mass functions are also derived, finding an increase of M* with cosmic time and a possible steepening of the low-mass slope from z ∼ 6 to z ∼ 5 with no significant change to z ∼ 4. Additionally, we have derived the SFR–Mstar relation, finding an SFR∝Mβstar behaviour with negligible evolution from z ∼ 4 to z ∼ 6
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